window resizing sorted sort of

.clangd

@@ -0,0 +1,3 @@
+CompileFlags:
+  Add: [-I/home/sebastian/code/viseq/include, -std=c++23]
+

.gitignore

@@ -1,4 +1,6 @@
 build/**
 .cache
 viseq
+viseq.exe
 compile_commands.json
+*.json

Makefile

@@ -1,32 +1,21 @@
-CXX = g++
+.PHONY: clean
-CXXFLAGS = -std=c++23 -Wall -g -fno-omit-frame-pointer -gdwarf-4 -Og -Wnarrowing -DLIBREMIDI_ALSA=1
-CXXINC = -Iinclude
 
-LDLIBS = -lraylib -lasound -pthread 
+CXX := g++
-LDFLAGS = -Llib -L/usr/lib -L/usr/local/lib
+CXXFLAGS := -std=c++23 -Wall -g -fno-omit-frame-pointer -gdwarf-4 -Og -Wnarrowing -DLIBREMIDI_ALSA=1 -DLIBREMIDI_HEADER_ONLY=1
+CXXINC := -Iinclude -isysteminclude
 
-hdr_files = ${wildcard src/*.h}
+LDLIBS := -lraylib -lasound -llibremidi -pthread 
+LDFLAGS := -Llib -L/usr/lib -L/usr/local/lib
 
-src_files = ${wildcard src/*.cpp}
+SRCS := $(wildcard src/*.cpp)
-src_files += ${wildcard include/libremidi/*.cpp}
+OBJECTS := $(patsubst src/%.cpp,build/%.o, $(SRCS))
 
-all: viseq
+viseq: $(OBJECTS)
+	$(CXX) $(OBJECTS) -o $@ $(LDFLAGS) $(LDLIBS)
 
-viseq: $(src_files) $(hdr_files)
+$(OBJECTS): build/%.o : src/%.cpp
-	mkdir -p build
+	@mkdir -p build
-	$(CXX) ${wildcard build/*.o} -o viseq $(LDFLAGS) $(LDLIBS)
+	$(CXX) -c $< -o $@ $(CXXFLAGS) $(CXXINC)
-	
-$(src_files): %.cpp : %_src
-	$(CXX) -c $@ -o build/$(*F).o $(CXXFLAGS) $(CXXINC)
-
-$(hdr_files): %.h : %_hdr
-	@echo "G++  >---------- $(*F).h -----------<"
-
-%_src:
-	@echo "G++  >---------- $(*F).cpp -----------<"
-
-%_hdr:
-	@echo "G++  >---------- $(*F).h -----------<"
 
 clean:
 	rm -f build/*

MakefileMingW64

@@ -0,0 +1,33 @@
+CXX = g++
+CXXFLAGS = -std=c++23 -Wall -g -fno-omit-frame-pointer -gdwarf-4 -Og -Wnarrowing -DLIBREMIDI_WINUWP=1
+CXXINC = -Iinclude
+
+LDLIBS = -lraylibdll -pthread -lwindowsapp
+LDFLAGS = -L./lib -L/usr/lib -L/usr/local/lib
+
+hdr_files = ${wildcard src/*.h}
+
+src_files = ${wildcard src/*.cpp}
+src_files += ${wildcard include/libremidi/*.cpp}
+
+all: viseq
+	
+viseq: $(src_files) $(hdr_files)
+	mkdir -p build
+	$(CXX) ${wildcard build/*.o} -o viseq $(LDFLAGS) $(LDLIBS)
+	
+$(src_files): %.cpp : %_src
+	$(CXX) -c $@ -o build/$(*F).o $(CXXFLAGS) $(CXXINC)
+
+$(hdr_files): %.h : %_hdr
+	@echo "G++  >---------- $(*F).h -----------<"
+
+%_src:
+	@echo "G++  >---------- $(*F).cpp -----------<"
+
+%_hdr:
+	@echo "G++  >---------- $(*F).h -----------<"
+
+clean:
+	rm -f build/*
+	rm -f viseq

include/libremidi/api-c.h

@@ -0,0 +1,48 @@
+#pragma once
+#ifndef LIBREMIDI_API_C_H
+#define LIBREMIDI_API_C_H
+
+#if __cplusplus && !defined(LIBREMIDI_MODULE_BUILD)
+extern "C" {
+#endif
+
+//! MIDI API specifier arguments.
+//! To get information on which feature is supported by each back-end, check their backend file
+//! in e.g. backends/winmm.hpp, etc.
+enum libremidi_api
+{
+  UNSPECIFIED = 0x0, /*!< Search for a working compiled API. */
+
+  // MIDI 1.0 APIs
+  COREMIDI = 0x1, /*!< macOS CoreMidi API. */
+  ALSA_SEQ,       /*!< Linux ALSA Sequencer API. */
+  ALSA_RAW,       /*!< Linux Raw ALSA API. */
+  JACK_MIDI,      /*!< JACK Low-Latency MIDI Server API. */
+  WINDOWS_MM,     /*!< Microsoft Multimedia MIDI API. */
+  WINDOWS_UWP,    /*!< Microsoft WinRT MIDI API. */
+  WEBMIDI,        /*!< Web MIDI API through Emscripten */
+  PIPEWIRE,       /*!< PipeWire */
+  KEYBOARD,       /*!< Computer keyboard input */
+  NETWORK,        /*!< MIDI over IP */
+  ANDROID_AMIDI,  /*!< Android AMidi API */
+  KDMAPI,         /*!< OmniMIDI KDMAPI (Windows) */
+
+  // MIDI 2.0 APIs
+  ALSA_RAW_UMP = 0x1000, /*!< Raw ALSA API for MIDI 2.0 */
+  ALSA_SEQ_UMP,          /*!< Linux ALSA Sequencer API for MIDI 2.0 */
+  COREMIDI_UMP,          /*!< macOS CoreMidi API for MIDI 2.0. Requires macOS 11+ */
+  WINDOWS_MIDI_SERVICES, /*!< Windows API for MIDI 2.0. Requires Windows 11 */
+  KEYBOARD_UMP,          /*!< Computer keyboard input */
+  NETWORK_UMP,           /*!< MIDI2 over IP */
+  JACK_UMP,              /*!< MIDI2 over JACK, type "32 bit raw UMP". Requires PipeWire v1.4+. */
+  PIPEWIRE_UMP,          /*!< MIDI2 over PipeWire. Requires v1.4+. */
+
+  DUMMY = 0xFFFF /*!< A compilable but non-functional API. */
+};
+
+typedef enum libremidi_api libremidi_api;
+
+#if __cplusplus && !defined(LIBREMIDI_MODULE_BUILD)
+}
+#endif
+#endif

include/libremidi/api.hpp

@@ -1,36 +1,16 @@
 #pragma once
+#include <libremidi/api-c.h>
 #include <libremidi/config.hpp>
 
 #include <string_view>
 #include <vector>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 //! MIDI API specifier arguments.
 //! To get information on which feature is supported by each back-end, check their backend file
 //! in e.g. backends/winmm.hpp, etc.
-enum class API
+using API = libremidi_api;
-{
-  UNSPECIFIED, /*!< Search for a working compiled API. */
-
-  // MIDI 1.0 APIs
-  COREMIDI,    /*!< macOS CoreMidi API. */
-  ALSA_SEQ,    /*!< Linux ALSA Sequencer API. */
-  ALSA_RAW,    /*!< Linux Raw ALSA API. */
-  JACK_MIDI,   /*!< JACK Low-Latency MIDI Server API. */
-  WINDOWS_MM,  /*!< Microsoft Multimedia MIDI API. */
-  WINDOWS_UWP, /*!< Microsoft WinRT MIDI API. */
-  WEBMIDI,     /*!< Web MIDI API through Emscripten */
-  PIPEWIRE,    /*!< PipeWire */
-
-  // MIDI 2.0 APIs
-  ALSA_RAW_UMP,          /*!< Raw ALSA API for MIDI 2.0 */
-  ALSA_SEQ_UMP,          /*!< Linux ALSA Sequencer API for MIDI 2.0 */
-  COREMIDI_UMP,          /*!< macOS CoreMidi API for MIDI 2.0. Requires macOS 11+ */
-  WINDOWS_MIDI_SERVICES, /*!< Windows API for MIDI 2.0. Requires Windows 11 */
-
-  DUMMY /*!< A compilable but non-functional API. */
-};
 
 /**
  * \brief A function to determine the available compiled MIDI 1.0 APIs.
@@ -60,6 +40,17 @@ LIBREMIDI_EXPORT std::string_view get_api_display_name(libremidi::API api);
 //! Look-up an API through its name
 LIBREMIDI_EXPORT libremidi::API get_compiled_api_by_name(std::string_view api);
 
+inline constexpr bool is_midi1(libremidi::API api)
+{
+  return (static_cast<int>(api) >= 0x1 && static_cast<int>(api) < 0x1000)
+         || api == libremidi::API::DUMMY;
+}
+
+inline constexpr bool is_midi2(libremidi::API api)
+{
+  return static_cast<int>(api) >= 0x1000;
+}
+
 namespace midi1
 {
 //! Returns the default MIDI 1.0 backend to use for the target OS.
@@ -69,10 +60,12 @@ inline constexpr libremidi::API default_api() noexcept
   return API::COREMIDI;
 #elif defined(_WIN32)
   return API::WINDOWS_MM;
-#elif defined(__linux__)
+#elif defined(LIBREMIDI_ALSA)
   return API::ALSA_SEQ;
 #elif defined(__emscripten__)
   return API::EMSCRIPTEN_WEBMIDI;
+#elif defined(LIBREMIDI_ANDROID)
+  return API::ANDROID_AMIDI;
 #else
   return API::DUMMY;
 #endif
@@ -88,7 +81,7 @@ inline constexpr libremidi::API default_api() noexcept
   return API::COREMIDI_UMP;
 #elif defined(_WIN32)
   return API::WINDOWS_MIDI_SERVICES;
-#elif defined(__linux__)
+#elif defined(LIBREMIDI_ALSA)
   return API::ALSA_SEQ_UMP;
 #elif defined(__emscripten__)
   return API::DUMMY;

include/libremidi/backends.hpp

@@ -1,4 +1,6 @@
 #pragma once
+#include <libremidi/config.hpp>
+
 #include <tuple>
 
 #if !__has_include(<weak_libjack.h>) && !__has_include(<jack/jack.h>)
@@ -27,10 +29,16 @@
 
 #if defined(LIBREMIDI_JACK)
   #include <libremidi/backends/jack.hpp>
+  #if defined(LIBREMIDI_HAS_JACK_GET_VERSION)
+    #include <libremidi/backends/jack_ump.hpp>
+  #endif
 #endif
 
 #if defined(LIBREMIDI_PIPEWIRE)
   #include <libremidi/backends/pipewire.hpp>
+  #if defined(LIBREMIDI_PIPEWIRE_UMP)
+    #include <libremidi/backends/pipewire_ump.hpp>
+  #endif
 #endif
 
 #if defined(LIBREMIDI_COREMIDI)
@@ -42,11 +50,16 @@
   #include <libremidi/backends/winmm.hpp>
 #endif
 
+#if defined(LIBREMIDI_KDMAPI)
+  #include <libremidi/backends/kdmapi.hpp>
+#endif
+
 #if defined(LIBREMIDI_WINUWP)
   #include <libremidi/backends/winuwp.hpp>
-  #if __has_include(<winrt/Microsoft.Devices.Midi2.h>)
-    #include <libremidi/backends/winmidi.hpp>
 #endif
+
+#if defined(LIBREMIDI_WINMIDI)
+  #include <libremidi/backends/winmidi.hpp>
 #endif
 
 #if defined(LIBREMIDI_EMSCRIPTEN)
@@ -55,7 +68,20 @@
 
 #include <libremidi/backends/dummy.hpp>
 
-namespace libremidi
+#if defined(LIBREMIDI_KEYBOARD)
+  #include <libremidi/backends/keyboard.hpp>
+#endif
+
+#if defined(LIBREMIDI_NETWORK)
+  #include <libremidi/backends/network.hpp>
+  #include <libremidi/backends/network_ump.hpp>
+#endif
+
+#if defined(LIBREMIDI_ANDROID)
+  #include <libremidi/backends/android/android.hpp>
+#endif
+
+NAMESPACE_LIBREMIDI
 {
 // The order here will control the order of the API search in
 // the constructor.
@@ -67,7 +93,7 @@ constexpr auto make_tl(unused, Args...)
 
 namespace midi1
 {
-static constexpr auto available_backends = make_tl(
+LIBREMIDI_STATIC constexpr auto available_backends = make_tl(
     0
 #if defined(LIBREMIDI_ALSA)
     ,
@@ -85,6 +111,10 @@ static constexpr auto available_backends = make_tl(
     ,
     winmm_backend{}
 #endif
+#if defined(LIBREMIDI_KDMAPI)
+    ,
+    kdmapi_backend{}
+#endif
 #if defined(LIBREMIDI_WINUWP)
     ,
     winuwp_backend{}
@@ -100,6 +130,18 @@ static constexpr auto available_backends = make_tl(
 #if defined(LIBREMIDI_PIPEWIRE)
     ,
     pipewire::backend{}
+#endif
+#if defined(LIBREMIDI_KEYBOARD)
+    ,
+    kbd_backend{}
+#endif
+#if defined(LIBREMIDI_NETWORK)
+    ,
+    net::backend{}
+#endif
+#if defined(LIBREMIDI_ANDROID)
+    ,
+    android::backend{}
 #endif
     ,
     dummy_backend{});
@@ -125,7 +167,7 @@ auto for_backend(libremidi::API api, F&& f)
 
 namespace midi2
 {
-static constexpr auto available_backends = make_tl(
+LIBREMIDI_STATIC constexpr auto available_backends = make_tl(
     0
 #if defined(LIBREMIDI_ALSA) && LIBREMIDI_ALSA_HAS_UMP
     ,
@@ -135,15 +177,21 @@ static constexpr auto available_backends = make_tl(
     ,
     coremidi_ump::backend{}
 #endif
-#if defined(LIBREMIDI_JACK)
+#if defined(LIBREMIDI_WINMIDI)
-#endif
-#if defined(LIBREMIDI_WINUWP)
-  #if __has_include(<winrt/Microsoft.Devices.Midi2.h>)
     ,
     winmidi::backend{}
 #endif
+#if defined(LIBREMIDI_NETWORK)
+    ,
+    net_ump::backend{}
 #endif
-#if defined(LIBREMIDI_EMSCRIPTEN)
+#if defined(LIBREMIDI_JACK) && defined(LIBREMIDI_HAS_JACK_GET_VERSION)
+    ,
+    jack_ump::backend{}
+#endif
+#if defined(LIBREMIDI_PIPEWIRE_UMP)
+    ,
+    pipewire_ump::backend{}
 #endif
     ,
     dummy_backend{});
@@ -154,7 +202,7 @@ static_assert(std::tuple_size_v<decltype(available_backends)> >= 1);
 template <typename F>
 auto for_all_backends(F&& f)
 {
-  std::apply([&](auto&&... x) { (f(x), ...); }, available_backends);
+  std::apply([&](auto&&... x) { ((x.available() && (f(x), true)), ...); }, available_backends);
 }
 
 template <typename F>
@@ -183,5 +231,49 @@ auto for_backend(libremidi::API api, F&& f)
   midi2::for_backend(api, f);
 }
 
+void for_input_configuration(auto f, libremidi::input_api_configuration& api_conf)
+{
+  auto from_api = [&]<typename T>(T& /*backend*/) mutable {
+    if (auto conf = get_if<typename T::midi_in_configuration>(&api_conf))
+    {
+      f(*conf);
+      return true;
+    }
+    return false;
+  };
+  if (std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi1::available_backends))
+    return;
+  std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi2::available_backends);
+}
+
+void for_output_configuration(auto f, libremidi::output_api_configuration& api_conf)
+{
+  auto from_api = [&]<typename T>(T& /*backend*/) mutable {
+    if (auto conf = get_if<typename T::midi_out_configuration>(&api_conf))
+    {
+      f(*conf);
+      return true;
+    }
+    return false;
+  };
+  if (std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi1::available_backends))
+    return;
+  std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi2::available_backends);
+}
+
+void for_observer_configuration(auto f, libremidi::observer_api_configuration& api_conf)
+{
+  auto from_api = [&]<typename T>(T& /*backend*/) mutable {
+    if (auto conf = get_if<typename T::midi_observer_configuration>(&api_conf))
+    {
+      f(*conf);
+      return true;
+    }
+    return false;
+  };
+  if (std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi1::available_backends))
+    return;
+  std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi2::available_backends);
+}
 }
 }

include/libremidi/backends/alsa_raw.hpp

@@ -3,12 +3,13 @@
 #include <libremidi/backends/alsa_raw/midi_out.hpp>
 #include <libremidi/backends/alsa_raw/observer.hpp>
 
+#include <string_view>
 // Credits: greatly inspired from
 // https://ccrma.stanford.edu/~craig/articles/linuxmidi/alsa-1.0/alsarawmidiout.c
 // https://ccrma.stanford.edu/~craig/articles/linuxmidi/alsa-1.0/alsarawportlist.c
 // Thanks Craig Stuart Sapp <craig@ccrma.stanford.edu>
 
-namespace libremidi::alsa_raw
+NAMESPACE_LIBREMIDI::alsa_raw
 {
 struct backend
 {
@@ -19,8 +20,8 @@ struct backend
   using midi_out_configuration = alsa_raw_output_configuration;
   using midi_observer_configuration = alsa_raw_observer_configuration;
   static const constexpr auto API = libremidi::API::ALSA_RAW;
-  static const constexpr auto name = "alsa_raw";
+  static const constexpr std::string_view name = "alsa_raw";
-  static const constexpr auto display_name = "ALSA (raw)";
+  static const constexpr std::string_view display_name = "ALSA (raw)";
 
   static inline bool available() noexcept
   {

include/libremidi/backends/alsa_raw/config.hpp

@@ -2,6 +2,7 @@
 #include <libremidi/config.hpp>
 
 #include <chrono>
+#include <cstdint>
 #include <functional>
 #include <optional>
 #include <span>
@@ -9,12 +10,12 @@
 
 #if __has_include(<poll.h>)
   #include <poll.h>
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 using poll_descriptors = pollfd;
 }
 #else
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct poll_descriptors
 {
@@ -25,7 +26,7 @@ struct poll_descriptors
 }
 #endif
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 /**
@@ -61,6 +62,7 @@ struct manual_poll_parameters
 struct alsa_raw_input_configuration
 {
   std::function<bool(const manual_poll_parameters&)> manual_poll;
+  std::chrono::milliseconds poll_period{2};
 };
 
 struct alsa_raw_output_configuration

include/libremidi/backends/alsa_raw/helpers.hpp

@@ -2,15 +2,17 @@
 #include <libremidi/backends/linux/alsa.hpp>
 #include <libremidi/config.hpp>
 #include <libremidi/detail/observer.hpp>
+#include <libremidi/observer_configuration.hpp>
 
-#include <chrono>
+#include <alsa/asoundlib.h>
-#include <functional>
+
-#include <iostream>
+#include <cerrno>
-#include <optional>
+#include <cstdint>
-#include <span>
+#include <cstdio>
+#include <cstdlib>
 #include <string>
 #include <string_view>
-#include <thread>
+#include <system_error>
 #include <vector>
 
 // Credits: greatly inspired from
@@ -18,9 +20,7 @@
 // https://ccrma.stanford.edu/~craig/articles/linuxmidi/alsa-1.0/alsarawportlist.c
 // Thanks Craig Stuart Sapp <craig@ccrma.stanford.edu>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
-{
-namespace
 {
 struct alsa_raw_port_id
 {
@@ -32,25 +32,25 @@ struct alsa_raw_port_id
 };
 inline constexpr port_handle raw_to_port_handle(alsa_raw_port_id id) noexcept
 {
-  return (uint64_t(id.card) << 32) + (uint64_t(id.dev) << 16) + id.port;
+  return (uint64_t(id.port) << 32) + (uint64_t(id.dev) << 16) + id.card;
 }
 inline constexpr alsa_raw_port_id raw_from_port_handle(port_handle p) noexcept
 {
   alsa_raw_port_id ret;
-  ret.card = (p & 0x00'00'FF'FF'00'00'00'00) >> 32;
+  ret.port = (p & 0x00'00'FF'FF'00'00'00'00) >> 32;
   ret.dev = (p & 0x00'00'00'00'FF'FF'00'00) >> 16;
-  ret.port = (p & 0x00'00'00'00'00'00'FF'FF);
+  ret.card = (p & 0x00'00'00'00'00'00'FF'FF);
   return ret;
 }
 static_assert(raw_from_port_handle(raw_to_port_handle({102, 7, 3})).card == 102);
 static_assert(raw_from_port_handle(raw_to_port_handle({12, 7, 3})).dev == 7);
 static_assert(raw_from_port_handle(raw_to_port_handle({12, 7, 3})).port == 3);
-}
 
 namespace alsa_raw
 {
 struct alsa_raw_port_info
 {
+  // hw:1,2,0
   std::string device;
   std::string card_name;
   std::string device_name;
@@ -87,39 +87,15 @@ struct snd_ctl_wrapper
 struct enumerator
 {
   const libasound& snd = libasound::instance();
+  const error_handler& handler;
+  const observer_configuration& configuration;
   std::vector<alsa_raw_port_info> inputs;
   std::vector<alsa_raw_port_info> outputs;
 
-  std::function<void(std::string_view)> error_callback;
+  explicit enumerator(const auto& self)
-  std::function<void(std::string_view)> warn_callback;
+      : handler{self}
-
+      , configuration{self.configuration}
-  template <typename... Args>
-  void warning(Args&&... args)
   {
-    std::string s;
-    ((s += args), ...);
-    if (warn_callback)
-    {
-      warn_callback(std::move(s));
-    }
-    else
-    {
-      std::cerr << s << std::endl;
-    }
-  }
-  template <typename... Args>
-  void error(Args&&... args)
-  {
-    std::string s;
-    ((s += args), ...);
-    if (error_callback)
-    {
-      error_callback(std::move(s));
-    }
-    else
-    {
-      throw std::runtime_error(s.c_str());
-    }
   }
 
   // 1: is an input / output
@@ -141,9 +117,10 @@ struct enumerator
     }
     else if (status < 0 && status != -ENXIO)
     {
-      error(
+      handler.libremidi_handle_error(
-          "alsa_raw_helpers::enumerator::is: cannot get rawmidi information:", card, device, sub,
+          configuration,
-          snd.strerror(status));
+          "Cannot get rawmidi information: " + device_identifier(card, device, sub) + " : "
+              + snd.strerror(status));
       return status;
     }
     else
@@ -185,26 +162,23 @@ struct enumerator
     return s;
   }
 
-  void enumerate_cards()
+  stdx::error enumerate_cards()
   {
+    using namespace std::literals;
     int card = -1;
 
     int status = snd.card.next(&card);
     if (status < 0)
     {
-      error(
+      handler.libremidi_handle_error(
-          "alsa_raw_helpers::enumerator::enumerate_cards: "
+          configuration, "Cannot determine card number: "s + snd.strerror(status));
-          "cannot determine card number: ",
+      return from_errc(status);
-          snd.strerror(status));
-      return;
     }
 
     if (card < 0)
     {
-      error(
+      handler.libremidi_handle_error(configuration, "No sound cards found");
-          "alsa_raw_helpers::enumerator::enumerate_cards: "
+      return std::errc::no_such_device;
-          "no sound cards found");
-      return;
     }
 
     while (card >= 0)
@@ -213,13 +187,12 @@ struct enumerator
 
       if ((status = snd.card.next(&card)) < 0)
       {
-        error(
+        handler.libremidi_handle_error(
-            "alsa_raw_helpers::enumerator::enumerate_cards: "
+            configuration, "cannot determine card number: "s + snd.strerror(status));
-            "cannot determine card number: ",
+        return std::errc::no_such_device;
-            snd.strerror(status));
-        break;
       }
     }
+    return stdx::error{};
   }
 
   virtual void enumerate_devices(int card) = 0;
@@ -228,20 +201,23 @@ struct enumerator
 inline snd_ctl_wrapper::snd_ctl_wrapper(enumerator& self, const char* name)
     : snd{self.snd}
 {
+  using namespace std::literals;
   int status = snd.ctl.open(&ctl, name, 0);
   if (status < 0)
   {
-    self.error(
+    self.handler.libremidi_handle_error(
-        "alsa_raw_helpers::enumerator::snd_ctl_wrapper: "
+        self.configuration,
-        "cannot open control for card",
+        "cannot open control for card"s + name + " : " + snd.strerror(status));
-        name, snd.strerror(status));
   }
 }
 
 struct midi1_enumerator : enumerator
 {
+  using alsa_raw::enumerator::enumerator;
+
   void enumerate_devices(int card) override
   {
+    using namespace std::literals;
     char name[128];
 
     sprintf(name, "hw:%d", card);
@@ -261,10 +237,8 @@ struct midi1_enumerator : enumerator
 
       if (status < 0)
       {
-        error(
+        handler.libremidi_handle_error(
-            "alsa_raw::midi1_enumerator::enumerate_devices: "
+            configuration, "Cannot determine device number: "s + snd.strerror(status));
-            "cannot determine device number: ",
-            snd.strerror(status));
         break;
       }
 

include/libremidi/backends/alsa_raw/midi_in.hpp

@@ -10,7 +10,7 @@
 #include <chrono>
 #include <thread>
 
-namespace libremidi::alsa_raw
+NAMESPACE_LIBREMIDI::alsa_raw
 {
 class midi_in_impl
     : public midi1::in_api
@@ -33,83 +33,72 @@ public:
 
   ~midi_in_impl() override { }
 
-  bool open_virtual_port(std::string_view) override
-  {
-    warning(configuration, "midi_in_alsa_raw: open_virtual_port unsupported");
-    return false;
-  }
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_alsa_raw: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_alsa_raw: set_port_name unsupported");
-  }
-
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW; }
 
   // Must be a string such as: "hw:2,4,1"
-  [[nodiscard]] int do_init_port(const char* portname)
+  [[nodiscard]] stdx::error do_init_port(const char* portname)
   {
     constexpr int mode = SND_RAWMIDI_NONBLOCK;
     if (const int err = snd.rawmidi.open(&midiport_, nullptr, portname, mode); err < 0)
     {
-      error<driver_error>(this->configuration, "midi_in_alsa_raw::open_port: cannot open device.");
+      libremidi_handle_error(this->configuration, "cannot open device.");
-      return err;
+      return from_errc(err);
     }
 
     snd_rawmidi_params_t* params{};
     snd_rawmidi_params_alloca(&params);
 
     if (const int err = snd.rawmidi.params_current(midiport_, params); err < 0)
-      return err;
+      return from_errc(err);
     if (const int err = snd.rawmidi.params_set_no_active_sensing(midiport_, params, 1); err < 0)
-      return err;
+      return from_errc(err);
 #if LIBREMIDI_ALSA_HAS_RAWMIDI_TREAD
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
       if (const int err
           = snd.rawmidi.params_set_read_mode(midiport_, params, SND_RAWMIDI_READ_STANDARD);
           err < 0)
-        return err;
+        return from_errc(err);
       if (const int err
           = snd.rawmidi.params_set_clock_type(midiport_, params, SND_RAWMIDI_CLOCK_NONE);
           err < 0)
-        return err;
+        return from_errc(err);
     }
     else
     {
       if (const int err
           = snd.rawmidi.params_set_read_mode(midiport_, params, SND_RAWMIDI_READ_TSTAMP);
           err < 0)
-        return err;
+        return from_errc(err);
       if (const int err
           = snd.rawmidi.params_set_clock_type(midiport_, params, SND_RAWMIDI_CLOCK_MONOTONIC);
           err < 0)
-        return err;
+        return from_errc(err);
     }
 #endif
 
     if (const int err = snd.rawmidi.params(midiport_, params); err < 0)
-      return err;
+      return from_errc(err);
 
     return init_pollfd();
   }
 
-  [[nodiscard]] int init_port(const port_information& p)
+  [[nodiscard]] stdx::error init_port(const port_information& p)
   {
     return do_init_port(raw_from_port_handle(p.port).to_string().c_str());
   }
 
-  [[nodiscard]] int init_pollfd()
+  [[nodiscard]] stdx::error init_pollfd()
   {
     const int num_fds = snd.rawmidi.poll_descriptors_count(this->midiport_);
 
     this->fds_.clear();
     this->fds_.resize(num_fds);
 
-    return snd.rawmidi.poll_descriptors(this->midiport_, fds_.data(), num_fds);
+    int ret = snd.rawmidi.poll_descriptors(this->midiport_, fds_.data(), num_fds);
+    if (ret < 0)
+      return from_errc(ret);
+    return stdx::error{};
   }
 
   ssize_t do_read_events(auto parse_func, std::span<pollfd> fds)
@@ -155,7 +144,8 @@ public:
     while ((err = snd.rawmidi.read(this->midiport_, bytes, nbytes)) > 0)
     {
       const auto to_ns = [this] { return absolute_timestamp(); };
-      decoder_.on_bytes({bytes, bytes + err}, decoder_.timestamp<timestamp_info>(to_ns, 0));
+      m_processing.on_bytes(
+          {bytes, bytes + err}, m_processing.timestamp<timestamp_info>(to_ns, 0));
     }
     return err;
   }
@@ -180,7 +170,8 @@ public:
       const auto to_ns = [ts] {
         return static_cast<int64_t>(ts.tv_sec) * 1'000'000'000 + static_cast<int64_t>(ts.tv_nsec);
       };
-      decoder_.on_bytes({bytes, bytes + err}, decoder_.timestamp<timestamp_info>(to_ns, 0));
+      m_processing.on_bytes(
+          {bytes, bytes + err}, m_processing.timestamp<timestamp_info>(to_ns, 0));
     }
     return err;
   }
@@ -188,18 +179,19 @@ public:
   ssize_t read_input_buffer_with_timestamps() { return read_input_buffer(); }
 #endif
 
-  void close_port() override
+  stdx::error close_port() override
   {
     if (midiport_)
       snd.rawmidi.close(midiport_);
     midiport_ = nullptr;
+    return stdx::error{};
   }
 
   timestamp absolute_timestamp() const noexcept final override { return system_ns(); }
 
   snd_rawmidi_t* midiport_{};
   std::vector<pollfd> fds_;
-  midi1::input_state_machine decoder_{this->configuration};
+  midi1::input_state_machine m_processing{this->configuration};
 };
 
 class midi_in_alsa_raw_threaded : public midi_in_impl
@@ -208,33 +200,40 @@ public:
   midi_in_alsa_raw_threaded(input_configuration&& conf, alsa_raw_input_configuration&& apiconf)
       : midi_in_impl{std::move(conf), std::move(apiconf)}
   {
-    if (this->termination_event < 0)
+    if (this->m_termination_event < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating eventfd.");
-          this->configuration, "midi_in_alsa::initialize: error creating eventfd.");
+      return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_in_alsa_raw_threaded() override
   {
     // Close a connection if it exists.
     this->midi_in_alsa_raw_threaded::close_port();
+
+    client_open_ = std::errc::not_connected;
   }
 
 private:
   void run_thread(auto parse_func)
   {
-    fds_.push_back(this->termination_event);
+    fds_.push_back(this->m_termination_event);
+    const auto period
+        = std::chrono::duration_cast<std::chrono::milliseconds>(this->configuration.poll_period)
+              .count();
 
     for (;;)
     {
       // Poll
-      ssize_t err = poll(fds_.data(), fds_.size(), -1);
+      ssize_t err = poll(fds_.data(), fds_.size(), static_cast<int32_t>(period));
       if (err == -EAGAIN)
         continue;
       else if (err < 0)
         return;
-      else if (termination_event.ready(fds_.back()))
+      else if (m_termination_event.ready(fds_.back()))
         break;
 
       err = do_read_events(parse_func, {fds_.data(), fds_.size() - 1});
@@ -245,64 +244,70 @@ private:
     }
   }
 
-  [[nodiscard]] ssize_t start_thread()
+  [[nodiscard]] stdx::error start_thread()
   {
     try
     {
       if (configuration.timestamps == timestamp_mode::NoTimestamp)
       {
-        this->thread_ = std::thread{[this] { run_thread(&midi_in_impl::read_input_buffer); }};
+        this->m_thread = std::thread{[this] { run_thread(&midi_in_impl::read_input_buffer); }};
       }
       else
       {
-        this->thread_ = std::thread{
+        this->m_thread = std::thread{
             [this] { run_thread(&midi_in_impl::read_input_buffer_with_timestamps); }};
       }
+      return stdx::error{};
     }
     catch (const std::system_error& e)
     {
       using namespace std::literals;
 
-      error<thread_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error starting MIDI input thread: "s + e.what());
-          "midi_in_alsa::start_thread: error starting MIDI input thread: "s + e.what());
+      return e.code();
-      return false;
     }
-    return true;
+    return stdx::error{};
   }
 
-  bool open_port(const input_port& port, std::string_view /*name*/) override
+  stdx::error open_port(const input_port& port, std::string_view /*name*/) override
   {
-    if (const int err = midi_in_impl::init_port(port); err < 0)
+    if (auto err = midi_in_impl::init_port(port); err != stdx::error{})
-      return false;
+      return err;
-    if (!start_thread())
+    if (auto err = start_thread(); err != stdx::error{})
-      return false;
+      return err;
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
-    termination_event.notify();
+    m_termination_event.notify();
-    if (thread_.joinable())
+    if (m_thread.joinable())
-      thread_.join();
+      m_thread.join();
-    termination_event.consume(); // Reset to zero
+    m_termination_event.consume(); // Reset to zero
 
-    midi_in_impl::close_port();
+    return midi_in_impl::close_port();
   }
 
-  std::thread thread_;
+  std::thread m_thread;
-  eventfd_notifier termination_event{};
+  eventfd_notifier m_termination_event{};
 };
 
 class midi_in_alsa_raw_manual : public midi_in_impl
 {
 public:
-  using midi_in_impl::midi_in_impl;
+  midi_in_alsa_raw_manual(input_configuration&& conf, alsa_raw_input_configuration&& apiconf)
+      : midi_in_impl{std::move(conf), std::move(apiconf)}
+  {
+    client_open_ = stdx::error{};
+  }
 
   ~midi_in_alsa_raw_manual()
   {
     // Close a connection if it exists.
     this->close_port();
+
+    client_open_ = std::errc::not_connected;
   }
 
 private:
@@ -310,7 +315,8 @@ private:
   {
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
+          manual_poll_parameters{
               .fds = {this->fds_.data(), this->fds_.size()},
               .callback = [this](std::span<pollfd> fds) {
         return do_read_events(&midi_in_impl::read_input_buffer, fds);
@@ -318,7 +324,8 @@ private:
     }
     else
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
+          manual_poll_parameters{
               .fds = {this->fds_.data(), this->fds_.size()},
               .callback = [this](std::span<pollfd> fds) {
         return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
@@ -326,17 +333,17 @@ private:
     }
   }
 
-  bool open_port(const input_port& p, std::string_view /*name*/) override
+  stdx::error open_port(const input_port& p, std::string_view /*name*/) override
   {
-    if (midi_in_impl::init_port(p) < 0)
+    if (auto err = midi_in_impl::init_port(p); err != stdx::error{})
-      return false;
+      return err;
     send_poll_callback();
-    return true;
+    return stdx::error{};
   }
 };
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<midi_in_api> make<alsa_raw::midi_in_impl>(

include/libremidi/backends/alsa_raw/midi_out.hpp

@@ -8,7 +8,7 @@
 #include <atomic>
 #include <thread>
 
-namespace libremidi::alsa_raw
+NAMESPACE_LIBREMIDI::alsa_raw
 {
 class midi_out_impl final
     : public midi1::out_api
@@ -26,83 +26,71 @@ public:
   midi_out_impl(output_configuration&& conf, alsa_raw_output_configuration&& apiconf)
       : configuration{std::move(conf), std::move(apiconf)}
   {
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_impl() override
   {
     // Close a connection if it exists.
     midi_out_impl::close_port();
+    client_open_ = std::errc::not_connected;
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW; }
 
-  bool open_virtual_port(std::string_view) override
+  stdx::error connect_port(const char* portname)
-  {
-    warning(configuration, "midi_out_alsa_raw: open_virtual_port unsupported");
-    return false;
-  }
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_alsa_raw: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_alsa_raw: set_port_name unsupported");
-  }
-
-  int connect_port(const char* portname)
   {
     constexpr int mode = SND_RAWMIDI_SYNC;
     int status = snd.rawmidi.open(NULL, &midiport_, portname, mode);
     if (status < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "cannot open device.");
-          this->configuration, "midi_out_alsa_raw::open_port: cannot open device.");
+      return from_errc(status);
-      return status;
     }
-    return status;
+    return stdx::error{};
   }
 
-  bool open_port(const output_port& p, std::string_view) override
+  stdx::error open_port(const output_port& p, std::string_view) override
   {
-    return connect_port(raw_from_port_handle(p.port).to_string().c_str()) == 0;
+    return connect_port(raw_from_port_handle(p.port).to_string().c_str());
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
     if (midiport_)
       snd.rawmidi.close(midiport_);
     midiport_ = nullptr;
+
+    return stdx::error{};
   }
 
-  void send_message(const unsigned char* message, size_t size) override
+  stdx::error send_message(const unsigned char* message, size_t size) override
   {
     if (!midiport_)
-      error<invalid_use_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_out_alsa_raw::send_message: trying to send a message without an open "
+          "trying to send a message without an open "
           "port.");
 
     if (!this->configuration.chunking)
     {
-      write(message, size);
+      return write(message, size);
     }
     else
     {
-      write_chunked(message, size);
+      return write_chunked(message, size);
     }
   }
 
-  bool write(const unsigned char* message, size_t size)
+  stdx::error write(const unsigned char* message, size_t size)
   {
-    if (snd.rawmidi.write(midiport_, message, size) < 0)
+    if (auto err = snd.rawmidi.write(midiport_, message, size); err < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "cannot write message.");
-          this->configuration, "midi_out_alsa_raw::send_message: cannot write message.");
+      return from_errc(err);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
   std::size_t get_chunk_size() const noexcept
@@ -125,7 +113,7 @@ public:
   }
 
   // inspired from ALSA amidi.c source code
-  void write_chunked(const unsigned char* const begin, size_t size)
+  stdx::error write_chunked(const unsigned char* const begin, size_t size)
   {
     const unsigned char* data = begin;
     const unsigned char* end = begin + size;
@@ -135,8 +123,8 @@ public:
     // Send the first buffer
     std::size_t len = chunk_size;
 
-    if (!write(data, len))
+    if (auto err = write(data, len); err != stdx::error{})
-      return;
+      return err;
 
     data += len;
 
@@ -149,11 +137,11 @@ public:
       {
         if (!configuration.chunking->wait(
                 std::chrono::microseconds((chunk_size - available) * 320), written_bytes))
-          return;
+          return std::errc::protocol_error;
       };
 
       if (!configuration.chunking->wait(configuration.chunking->interval, written_bytes))
-        return;
+        return std::errc::protocol_error;
 
       // Write more data
       len = end - data;
@@ -165,11 +153,13 @@ public:
       if (len > chunk_size)
         len = chunk_size;
 
-      if (!write(data, len))
+      if (auto err = write(data, len); err != stdx::error{})
-        return;
+        return err;
 
       data += len;
     }
+
+    return stdx::error{};
   }
 
   snd_rawmidi_t* midiport_{};

include/libremidi/backends/alsa_raw/observer.hpp

@@ -6,14 +6,15 @@
 #if LIBREMIDI_HAS_UDEV
   #include <libremidi/backends/linux/helpers.hpp>
   #include <libremidi/backends/linux/udev.hpp>
+#endif
 #include <libremidi/detail/observer.hpp>
 
-  #include <stdexcept>
+NAMESPACE_LIBREMIDI::alsa_raw
-
-namespace libremidi::alsa_raw
 {
 template <typename Enumerator>
-class observer_impl_base : public observer_api
+class observer_impl_base
+    : public observer_api
+    , public error_handler
 {
 public:
   struct
@@ -27,34 +28,45 @@ public:
   explicit observer_impl_base(
       observer_configuration&& conf, alsa_raw_observer_configuration&& apiconf)
       : configuration{std::move(conf), std::move(apiconf)}
+  {
+  }
+
+  ~observer_impl_base()
+  {
+#if LIBREMIDI_HAS_UDEV
+    m_termination_event.notify();
+
+    if (m_thread.joinable())
+      m_thread.join();
+#endif
+  }
+
+  // Must be called for child classes due to virtual function calls
+  void finish_init()
   {
     if (!configuration.has_callbacks())
       return;
 
-    fds[0] = this->udev;
+#if LIBREMIDI_HAS_UDEV
-    fds[1] = termination_event;
+    m_fds[0] = this->m_udev;
-    fds[2] = timer_fd;
+    m_fds[1] = m_termination_event;
+    m_fds[2] = m_timer_fd;
+#endif
 
     // Set-up initial state
     if (configuration.notify_in_constructor)
       this->check_devices();
 
+#if LIBREMIDI_HAS_UDEV
     // Start thread
-    thread = std::thread{[this] { this->run(); }};
+    m_thread = std::thread{[this] { this->run(); }};
-  }
+#endif
-
-  ~observer_impl_base()
-  {
-    termination_event.notify();
-
-    if (thread.joinable())
-      thread.join();
   }
 
   std::vector<libremidi::input_port> get_input_ports() const noexcept override
   {
     std::vector<libremidi::input_port> ret;
-    Enumerator new_devs;
+    Enumerator new_devs{*this};
 
     new_devs.enumerate_cards();
     for (auto& d : new_devs.inputs)
@@ -67,7 +79,7 @@ public:
   std::vector<libremidi::output_port> get_output_ports() const noexcept override
   {
     std::vector<libremidi::output_port> ret;
-    Enumerator new_devs;
+    Enumerator new_devs{*this};
 
     new_devs.enumerate_cards();
     for (auto& d : new_devs.outputs)
@@ -77,12 +89,12 @@ public:
     return ret;
   }
 
-private:
+#if LIBREMIDI_HAS_UDEV
   void run()
   {
     for (;;)
     {
-      if (int err = poll(fds, 3, -1); err < 0)
+      if (int err = poll(m_fds, 3, -1); err < 0)
       {
         if (err == -EAGAIN)
           continue;
@@ -90,68 +102,96 @@ private:
           return;
       }
 
-      // Check udev
+      // Check eventfd to see if we need to exit
-      if (fds[0].revents & POLLIN)
+      if (m_fds[1].revents & POLLIN)
       {
-        udev_device* dev = udev.udev.monitor_receive_device(udev.monitor);
+        break;
+      }
+
+      // Check udev
+      if (m_fds[0].revents & POLLIN)
+      {
+        udev_device* dev = m_udev.udev.monitor_receive_device(m_udev.monitor);
         if (!dev)
           continue;
 
-        std::string_view act = udev.udev.device_get_action(dev);
+        std::string_view act = m_udev.udev.device_get_action(dev);
-        std::string_view ss = udev.udev.device_get_subsystem(dev);
+        std::string_view ss = m_udev.udev.device_get_subsystem(dev);
         if (!act.empty() && ss == "snd_seq")
         {
           if (act == "add" || act == "remove")
           {
             // Check every 100 milliseconds for ten seconds
-            this->timer_fd.restart(configuration.poll_period.count());
+            this->m_timer_fd.restart(configuration.poll_period.count());
-            timer_check_counts = 100;
+            m_timer_check_counts = 100;
           }
         }
 
-        udev.udev.device_unref(dev);
+        m_udev.udev.device_unref(dev);
 
-        fds[0].revents = 0;
+        m_fds[0].revents = 0;
-      }
-
-      // Check eventfd
-      if (fds[1].revents & POLLIN)
-      {
-        break;
       }
 
       // Check timer
-      if (fds[2].revents & POLLIN)
+      if (m_fds[2].revents & POLLIN)
       {
-        if (this->timer_check_counts-- <= 0)
+        if (this->m_timer_check_counts-- <= 0)
-          this->timer_fd.cancel();
+          this->m_timer_fd.cancel();
-        fds[2].revents = 0;
+        m_fds[2].revents = 0;
 
         check_devices();
       }
     }
   }
+#endif
 
   template <bool Input>
-  auto to_port_info(alsa_raw::alsa_raw_port_info p) const noexcept
+  auto to_port_info(const alsa_raw::alsa_raw_port_info& p) const noexcept
       -> std::conditional_t<Input, input_port, output_port>
   {
+#if LIBREMIDI_HAS_UDEV
+    auto [container, device, type, manufacturer, product, serial]
+        = get_udev_soundcard_info(m_udev, p.card);
+#else
+    container_identifier container{};
+    device_identifier device{};
+    libremidi::transport_type type{};
+    std::string manufacturer;
+    std::string product;
+    std::string serial;
+#endif
+    std::string display_name = p.subdevice_name;
+    if (display_name.empty())
+      display_name = p.device_name;
+    if (display_name.empty())
+      display_name = p.card_name;
+    if (display_name.empty())
+      display_name = product;
+    if (display_name.empty())
+      display_name = "unknown";
+
     return {
-        {.client = 0,
+        {.api = get_current_api(),
+         .client = 0,
+         .container = container,
+         .device = device,
          .port = raw_to_port_handle({p.card, p.dev, p.sub}),
-         .manufacturer = p.card_name,
+         .manufacturer = manufacturer,
+         .product = product,
+         .serial = serial,
          .device_name = p.device_name,
          .port_name = p.subdevice_name,
-         .display_name = p.subdevice_name}};
+         .display_name = std::move(display_name),
+         .type = type}};
   }
 
   void check_devices()
   {
-    Enumerator new_devs;
+    Enumerator new_devs{*this};
 
     new_devs.enumerate_cards();
 
-    for (auto& in_prev : current_inputs)
+    for (auto& in_prev : m_current_inputs)
     {
       if (auto it = std::find(new_devs.inputs.begin(), new_devs.inputs.end(), in_prev);
           it == new_devs.inputs.end())
@@ -165,8 +205,8 @@ private:
 
     for (auto& in_next : new_devs.inputs)
     {
-      if (auto it = std::find(current_inputs.begin(), current_inputs.end(), in_next);
+      if (auto it = std::find(m_current_inputs.begin(), m_current_inputs.end(), in_next);
-          it == current_inputs.end())
+          it == m_current_inputs.end())
       {
         if (auto& cb = this->configuration.input_added)
         {
@@ -175,7 +215,7 @@ private:
       }
     }
 
-    for (auto& out_prev : current_outputs)
+    for (auto& out_prev : m_current_outputs)
     {
       if (auto it = std::find(new_devs.outputs.begin(), new_devs.outputs.end(), out_prev);
           it == new_devs.outputs.end())
@@ -189,8 +229,8 @@ private:
 
     for (auto& out_next : new_devs.outputs)
     {
-      if (auto it = std::find(current_outputs.begin(), current_outputs.end(), out_next);
+      if (auto it = std::find(m_current_outputs.begin(), m_current_outputs.end(), out_next);
-          it == current_outputs.end())
+          it == m_current_outputs.end())
       {
         if (auto& cb = this->configuration.output_added)
         {
@@ -198,43 +238,34 @@ private:
         }
       }
     }
-    current_inputs = std::move(new_devs.inputs);
+    m_current_inputs = std::move(new_devs.inputs);
-    current_outputs = std::move(new_devs.outputs);
+    m_current_outputs = std::move(new_devs.outputs);
   }
 
-  udev_helper udev{};
+#if LIBREMIDI_HAS_UDEV
-  eventfd_notifier termination_event{};
+  udev_helper m_udev{};
-  timerfd_timer timer_fd{};
+  eventfd_notifier m_termination_event{};
-  int timer_check_counts = 0;
+  timerfd_timer m_timer_fd{};
-  std::thread thread;
+  int m_timer_check_counts = 0;
-  std::vector<alsa_raw_port_info> current_inputs;
+  std::thread m_thread;
-  std::vector<alsa_raw_port_info> current_outputs;
+  pollfd m_fds[3]{};
-
-  pollfd fds[3]{};
-};
-}
-#else
-  #include <libremidi/backends/dummy.hpp>
-namespace libremidi::alsa_raw
-{
-template <typename Enumerator>
-struct observer_impl_base : observer_dummy
-{
-  explicit observer_impl_base(
-      [[maybe_unused]] observer_configuration&& conf,
-      [[maybe_unused]] alsa_raw_observer_configuration&& apiconf)
-      : observer_dummy{dummy_configuration{}, dummy_configuration{}}
-  {
-  }
-};
-}
 #endif
 
-namespace libremidi::alsa_raw
+  std::vector<alsa_raw_port_info> m_current_inputs;
+  std::vector<alsa_raw_port_info> m_current_outputs;
+};
+}
+
+NAMESPACE_LIBREMIDI::alsa_raw
 {
 struct observer_impl : observer_impl_base<alsa_raw::midi1_enumerator>
 {
-  using alsa_raw::observer_impl_base<midi1_enumerator>::observer_impl_base;
+  observer_impl(observer_configuration&& conf, alsa_raw_observer_configuration&& apiconf)
+      : observer_impl_base<alsa_raw::midi1_enumerator>{std::move(conf), std::move(apiconf)}
+  {
+    finish_init();
+  }
+
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW; }
 };
 }

include/libremidi/backends/alsa_raw_ump.hpp

@@ -5,7 +5,9 @@
 #include <libremidi/backends/alsa_raw_ump/observer.hpp>
 #include <libremidi/backends/dummy.hpp>
 
-namespace libremidi::alsa_raw_ump
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
 struct backend
 {
@@ -14,12 +16,11 @@ struct backend
   using midi_observer = observer_impl;
   using midi_in_configuration = alsa_raw_ump::input_configuration;
   using midi_out_configuration = alsa_raw_ump::output_configuration;
-  struct midi_observer_configuration : alsa_raw_observer_configuration
+  using midi_observer_configuration = alsa_raw_ump::observer_configuration;
-  {
+
-  };
   static const constexpr auto API = libremidi::API::ALSA_RAW_UMP;
-  static const constexpr auto name = "alsa_raw_ump";
+  static const constexpr std::string_view name = "alsa_raw_ump";
-  static const constexpr auto display_name = "ALSA (raw UMP)";
+  static const constexpr std::string_view display_name = "ALSA (raw UMP)";
 
   static inline bool available() noexcept
   {

include/libremidi/backends/alsa_raw_ump/config.hpp

@@ -1,11 +1,15 @@
 #pragma once
 #include <libremidi/backends/alsa_raw/config.hpp>
 
-namespace libremidi::alsa_raw_ump
+#include <chrono>
+#include <functional>
+
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
 struct input_configuration
 {
   std::function<bool(const manual_poll_parameters&)> manual_poll;
+  std::chrono::milliseconds poll_period{2};
 };
 
 struct output_configuration
@@ -17,8 +21,7 @@ struct output_configuration
   std::optional<chunking_parameters> chunking;
 };
 
-struct observer_configuration
+struct observer_configuration : public alsa_raw_observer_configuration
 {
-  std::chrono::milliseconds poll_period{100};
 };
 }

include/libremidi/backends/alsa_raw_ump/helpers.hpp

@@ -3,12 +3,16 @@
 #include <libremidi/config.hpp>
 #include <libremidi/detail/observer.hpp>
 
-namespace libremidi::alsa_raw_ump
+#include <cstdio>
+
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
 struct midi2_enumerator : alsa_raw::enumerator
 {
+  using alsa_raw::enumerator::enumerator;
   void enumerate_devices(int card) override
   {
+    using namespace std::literals;
     char name[128];
 
     sprintf(name, "hw:%d", card);
@@ -28,10 +32,8 @@ struct midi2_enumerator : alsa_raw::enumerator
 
       if (status < 0)
       {
-        error(
+        handler.libremidi_handle_error(
-            "alsa_raw_ump::midi2_enumerator::enumerate_devices: "
+            configuration, "Cannot determine device number: "s + snd.strerror(status));
-            "cannot determine device number: ",
-            snd.strerror(status));
         break;
       }
 

include/libremidi/backends/alsa_raw_ump/midi_in.hpp

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <thread>
 
-namespace libremidi::alsa_raw_ump
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
 class midi_in_impl
     : public midi2::in_api
@@ -35,32 +35,18 @@ public:
 
   ~midi_in_impl() override { }
 
-  bool open_virtual_port(std::string_view) override
-  {
-    warning(configuration, "alsa_raw_ump::ump: open_virtual_port unsupported");
-    return false;
-  }
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "alsa_raw_ump::ump: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "alsa_raw_ump::ump: set_port_name unsupported");
-  }
-
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW_UMP; }
 
   // Must be a string such as: "hw:2,4,1"
-  [[nodiscard]] int do_init_port(const char* portname)
+  [[nodiscard]] stdx::error do_init_port(const char* portname)
   {
     constexpr int mode = 0;
-    SND_RAWMIDI_NONBLOCK;
+    SND_RAWMIDI_NONBLOCK; // fixme
     if (int err = snd.ump.open(&midiport_, 0, portname, mode); err < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration, "alsa_raw_ump::ump::open_port: cannot open device.");
-      return err;
+      return from_errc(err);
     }
 
     snd_rawmidi_params_t* params{};
@@ -69,49 +55,52 @@ public:
     auto rawmidi = snd.ump.rawmidi(midiport_);
 
     if (int err = snd.ump.rawmidi_params_current(midiport_, params); err < 0)
-      return err;
+      return from_errc(err);
     if (int err = snd.rawmidi.params_set_no_active_sensing(rawmidi, params, 1); err < 0)
-      return err;
+      return from_errc(err);
 
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
       if (int err = snd.rawmidi.params_set_read_mode(rawmidi, params, SND_RAWMIDI_READ_STANDARD);
           err < 0)
-        return err;
+        return from_errc(err);
       if (int err = snd.rawmidi.params_set_clock_type(rawmidi, params, SND_RAWMIDI_CLOCK_NONE);
           err < 0)
-        return err;
+        return from_errc(err);
     }
     else
     {
       if (int err = snd.rawmidi.params_set_read_mode(rawmidi, params, SND_RAWMIDI_READ_TSTAMP);
           err < 0)
-        return err;
+        return from_errc(err);
       if (int err
           = snd.rawmidi.params_set_clock_type(rawmidi, params, SND_RAWMIDI_CLOCK_MONOTONIC);
           err < 0)
-        return err;
+        return from_errc(err);
     }
 
     if (int err = snd.ump.rawmidi_params(midiport_, params); err < 0)
-      return err;
+      return from_errc(err);
 
     return init_pollfd();
   }
 
-  [[nodiscard]] int init_port(const port_information& p)
+  [[nodiscard]] stdx::error init_port(const port_information& p)
   {
     return do_init_port(raw_from_port_handle(p.port).to_string().c_str());
   }
 
-  [[nodiscard]] int init_pollfd()
+  [[nodiscard]] stdx::error init_pollfd()
   {
     int num_fds = snd.ump.poll_descriptors_count(this->midiport_);
 
     this->fds_.clear();
     this->fds_.resize(num_fds);
 
-    return snd.ump.poll_descriptors(this->midiport_, fds_.data(), num_fds);
+    int ret = snd.ump.poll_descriptors(this->midiport_, fds_.data(), num_fds);
+    if (ret < 0)
+      return from_errc(ret);
+    return stdx::error{};
   }
 
   ssize_t do_read_events(auto parse_func, std::span<pollfd> fds)
@@ -143,95 +132,62 @@ public:
 
   ssize_t read_input_buffer()
   {
-    static const constexpr int nbytes = 1024;
+    static constexpr timestamp_backend_info timestamp_info{
-
+        .has_absolute_timestamps = false,
-    unsigned char bytes[nbytes];
+        .absolute_is_monotonic = false,
+        .has_samples = false,
+    };
+    static const constexpr int nwords = 64;
+    uint32_t words[nwords];
 
     ssize_t err = 0;
-    while ((err = snd.ump.read(this->midiport_, bytes, nbytes)) > 0)
+    while ((err = snd.ump.read(this->midiport_, words, nwords * 4)) > 0)
     {
-      std::cerr << "We read: " << nbytes << "bytes !!!!";
+      const auto to_ns = [this] { return absolute_timestamp(); };
-      return 1;
+      m_processing.on_bytes(
-      // err is the amount of bytes read
+          {words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
-      // decoder_.add_bytes(bytes, err);
     }
     return err;
   }
 
-  void set_timestamp(struct timespec ts, timestamp& res)
-  {
-    static constexpr int64_t nanos = 1e9;
-    switch (configuration.timestamps)
-    {
-      // Unneeded here
-      case timestamp_mode::NoTimestamp:
-        break;
-      case timestamp_mode::Relative: {
-        const auto t = static_cast<int64_t>(ts.tv_sec) * nanos + static_cast<int64_t>(ts.tv_nsec);
-        if (firstMessage == true)
-        {
-          firstMessage = false;
-          res = 0;
-        }
-        else
-        {
-          res = t - last_time;
-        }
-        last_time = t;
-        break;
-      }
-      case timestamp_mode::Absolute:
-      case timestamp_mode::SystemMonotonic:
-        res = static_cast<int64_t>(ts.tv_sec) * nanos + static_cast<int64_t>(ts.tv_nsec);
-        break;
-      case timestamp_mode::Custom:
-        res = configuration.get_timestamp(
-            static_cast<int64_t>(ts.tv_sec) * nanos + static_cast<int64_t>(ts.tv_nsec));
-        break;
-    }
-  }
-
   ssize_t read_input_buffer_with_timestamps()
   {
-    static const constexpr int nbytes = 1024;
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = true,
+        .absolute_is_monotonic = true,
+        .has_samples = false,
+    };
 
-    unsigned char bytes[nbytes];
+    static const constexpr int nwords = 64;
+    uint32_t words[nwords];
     struct timespec ts;
 
     ssize_t err = 0;
-    while ((err = snd.ump.tread(this->midiport_, &ts, bytes, nbytes)) > 0)
+    while ((err = snd.ump.tread(this->midiport_, &ts, words, nwords * 4)) > 0)
     {
-      // err is the amount of bytes read
+      const auto to_ns = [ts] {
-      int64_t ns{};
+        return static_cast<int64_t>(ts.tv_sec) * 1'000'000'000 + static_cast<int64_t>(ts.tv_nsec);
-      set_timestamp(ts, ns);
+      };
-      std::cerr << "We read: " << nbytes << "bytes !!!!";
+      m_processing.on_bytes(
-      return 1;
+          {words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
-      // decoder_.add_bytes(bytes, err, ns);
     }
     return err;
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
     if (midiport_)
       snd.ump.close(midiport_);
     midiport_ = nullptr;
+
+    return stdx::error{};
   }
 
   timestamp absolute_timestamp() const noexcept override { return system_ns(); }
 
-  midi2_enumerator get_device_enumerator() const noexcept
-  {
-    midi2_enumerator device_list;
-    device_list.error_callback
-        = [this](std::string_view text) { this->error<driver_error>(this->configuration, text); };
-    return device_list;
-  }
-
   snd_ump_t* midiport_{};
   std::vector<pollfd> fds_;
-  // midi_stream_decoder decoder_{this->configuration.on_message};
+  midi2::input_state_machine m_processing{this->configuration};
-  int64_t last_time{};
 };
 
 class midi_in_impl_threaded : public midi_in_impl
@@ -241,33 +197,39 @@ public:
       libremidi::ump_input_configuration&& conf, alsa_raw_ump::input_configuration&& apiconf)
       : midi_in_impl{std::move(conf), std::move(apiconf)}
   {
-    if (this->termination_event < 0)
+    if (this->m_termination_event < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating eventfd.");
-          this->configuration, "midi_in_alsa::initialize: error creating eventfd.");
+      return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_in_impl_threaded()
   {
     // Close a connection if it exists.
-    this->close_port();
+    midi_in_impl_threaded::close_port();
+    client_open_ = std::errc::not_connected;
   }
 
 private:
   void run_thread(auto parse_func)
   {
-    fds_.push_back(this->termination_event);
+    fds_.push_back(this->m_termination_event);
+    const auto period
+        = std::chrono::duration_cast<std::chrono::milliseconds>(this->configuration.poll_period)
+              .count();
 
     for (;;)
     {
       // Poll
-      ssize_t err = poll(fds_.data(), fds_.size(), -1);
+      ssize_t err = poll(fds_.data(), fds_.size(), static_cast<int32_t>(period));
       if (err == -EAGAIN)
         continue;
       else if (err < 0)
         return;
-      else if (termination_event.ready(fds_.back()))
+      else if (m_termination_event.ready(fds_.back()))
         break;
 
       err = do_read_events(parse_func, {fds_.data(), fds_.size() - 1});
@@ -278,64 +240,70 @@ private:
     }
   }
 
-  [[nodiscard]] int start_thread()
+  [[nodiscard]] stdx::error start_thread()
   {
     try
     {
       if (configuration.timestamps == timestamp_mode::NoTimestamp)
       {
-        this->thread_ = std::thread{[this] { run_thread(&midi_in_impl::read_input_buffer); }};
+        this->m_thread = std::thread{[this] { run_thread(&midi_in_impl::read_input_buffer); }};
       }
       else
       {
-        this->thread_ = std::thread{
+        this->m_thread = std::thread{
             [this] { run_thread(&midi_in_impl::read_input_buffer_with_timestamps); }};
       }
+      return stdx::error{};
     }
     catch (const std::system_error& e)
     {
       using namespace std::literals;
 
-      error<thread_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error starting MIDI input thread: "s + e.what());
-          "midi_in_alsa::start_thread: error starting MIDI input thread: "s + e.what());
+      return e.code();
-      return false;
     }
-    return true;
+    return stdx::error{};
   }
 
-  bool open_port(const input_port& port, [[maybe_unused]] std::string_view name) override
+  stdx::error open_port(const input_port& port, [[maybe_unused]] std::string_view name) override
   {
-    if (int err = midi_in_impl::init_port(port); err < 0)
+    if (auto err = midi_in_impl::init_port(port); err != stdx::error{})
-      return false;
+      return err;
-    if (!start_thread())
+    if (auto err = start_thread(); err != stdx::error{})
-      return false;
+      return err;
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
-    termination_event.notify();
+    m_termination_event.notify();
-    if (thread_.joinable())
+    if (m_thread.joinable())
-      thread_.join();
+      m_thread.join();
-    termination_event.consume(); // Reset to zero
+    m_termination_event.consume(); // Reset to zero
 
-    midi_in_impl::close_port();
+    return midi_in_impl::close_port();
   }
 
-  std::thread thread_;
+  std::thread m_thread;
-  eventfd_notifier termination_event{};
+  eventfd_notifier m_termination_event{};
 };
 
 class midi_in_impl_manual : public midi_in_impl
 {
 public:
-  using midi_in_impl::midi_in_impl;
+  midi_in_impl_manual(ump_input_configuration&& conf, alsa_raw_ump::input_configuration&& apiconf)
+      : midi_in_impl{std::move(conf), std::move(apiconf)}
+  {
+    client_open_ = stdx::error{};
+  }
 
   ~midi_in_impl_manual()
   {
     // Close a connection if it exists.
-    this->close_port();
+    midi_in_impl_manual::close_port();
+
+    client_open_ = std::errc::not_connected;
   }
 
 private:
@@ -343,7 +311,8 @@ private:
   {
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
+          manual_poll_parameters{
               .fds = {this->fds_.data(), this->fds_.size()},
               .callback = [this](std::span<pollfd> fds) {
         return do_read_events(&midi_in_impl::read_input_buffer, fds);
@@ -351,7 +320,8 @@ private:
     }
     else
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
+          manual_poll_parameters{
               .fds = {this->fds_.data(), this->fds_.size()},
               .callback = [this](std::span<pollfd> fds) {
         return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
@@ -359,17 +329,17 @@ private:
     }
   }
 
-  bool open_port(const input_port& p, [[maybe_unused]] std::string_view name) override
+  stdx::error open_port(const input_port& p, [[maybe_unused]] std::string_view name) override
   {
-    if (midi_in_impl::init_port(p) < 0)
+    if (auto err = midi_in_impl::init_port(p); err != stdx::error{})
-      return false;
+      return err;
     send_poll_callback();
-    return true;
+    return stdx::error{};
   }
 };
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<midi_in_api> make<alsa_raw_ump::midi_in_impl>(

include/libremidi/backends/alsa_raw_ump/midi_out.hpp

@@ -1,14 +1,19 @@
 #pragma once
 #include <libremidi/backends/alsa_raw_ump/config.hpp>
 #include <libremidi/backends/alsa_raw_ump/helpers.hpp>
+#include <libremidi/backends/linux/alsa.hpp>
 #include <libremidi/detail/midi_out.hpp>
+#include <libremidi/error_handler.hpp>
+#include <libremidi/output_configuration.hpp>
 
 #include <alsa/asoundlib.h>
 
-#include <atomic>
+#include <cassert>
-#include <thread>
+#include <cstdint>
+#include <system_error>
+#include <utility>
 
-namespace libremidi::alsa_raw_ump
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
 class midi_out_impl final
     : public midi2::out_api
@@ -29,76 +34,63 @@ public:
       : configuration{std::move(conf), std::move(apiconf)}
   {
     assert(snd.ump.available);
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_impl() override
   {
     // Close a connection if it exists.
     midi_out_impl::close_port();
+    client_open_ = std::errc::not_connected;
   }
 
-  libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW; }
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW_UMP; }
 
-  bool open_virtual_port(std::string_view) override
+  stdx::error connect_port(const char* portname)
-  {
-    warning(configuration, "midi_out_alsa_raw: open_virtual_port unsupported");
-    return false;
-  }
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_alsa_raw: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_alsa_raw: set_port_name unsupported");
-  }
-
-  int connect_port(const char* portname)
   {
     constexpr int mode = SND_RAWMIDI_SYNC;
-    int status = snd.ump.open(NULL, &midiport_, portname, mode);
+    int ret = snd.ump.open(NULL, &midiport_, portname, mode);
-    if (status < 0)
+    if (ret < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "cannot open device.");
-          this->configuration, "midi_out_alsa_raw::open_port: cannot open device.");
+      return from_errc(ret);
-      return status;
     }
-    return status;
+    return stdx::error{};
   }
 
-  bool open_port(const output_port& p, std::string_view) override
+  stdx::error open_port(const output_port& p, std::string_view) override
   {
-    return connect_port(raw_from_port_handle(p.port).to_string().c_str()) == 0;
+    return connect_port(raw_from_port_handle(p.port).to_string().c_str());
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
     if (midiport_)
       snd.ump.close(midiport_);
     midiport_ = nullptr;
+    return stdx::error{};
   }
 
-  void send_ump(const uint32_t* ump_stream, std::size_t count) override
+  stdx::error send_ump(const uint32_t* ump_stream, std::size_t count) override
   {
     if (!midiport_)
-      error<invalid_use_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_out_alsa_raw::send_message: trying to send a message without an open "
+          "trying to send a message without an open "
           "port.");
 
-    write(ump_stream, count * sizeof(uint32_t));
+    return write(ump_stream, count * sizeof(uint32_t));
   }
 
-  bool write(const uint32_t* ump_stream, size_t bytes)
+  stdx::error write(const uint32_t* ump_stream, size_t bytes)
   {
-    if (snd.ump.write(midiport_, ump_stream, bytes) < 0)
+    if (auto err = snd.ump.write(midiport_, ump_stream, bytes); err < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "cannot write message.");
-          this->configuration, "midi_out_alsa_raw::send_message: cannot write message.");
+      return from_errc(err);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
   snd_ump_t* midiport_{};

include/libremidi/backends/alsa_raw_ump/observer.hpp

@@ -2,13 +2,18 @@
 #include <libremidi/backends/alsa_raw/observer.hpp>
 #include <libremidi/backends/alsa_raw_ump/helpers.hpp>
 
-namespace libremidi::alsa_raw_ump
+NAMESPACE_LIBREMIDI::alsa_raw_ump
 {
-
 class observer_impl : public alsa_raw::observer_impl_base<midi2_enumerator>
 {
-  using alsa_raw::observer_impl_base<midi2_enumerator>::observer_impl_base;
+public:
+  observer_impl(
+      libremidi::observer_configuration&& conf, alsa_raw_ump::observer_configuration&& apiconf)
+      : observer_impl_base<alsa_raw_ump::midi2_enumerator>{std::move(conf), std::move(apiconf)}
+  {
+    finish_init();
+  }
+
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_RAW_UMP; }
 };
-
 }

include/libremidi/backends/alsa_seq.hpp

@@ -16,7 +16,11 @@
 #include <libremidi/backends/alsa_seq/midi_out.hpp>
 #include <libremidi/backends/alsa_seq/observer.hpp>
 
-namespace libremidi::alsa_seq
+#include <unistd.h>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 
 struct backend
@@ -29,13 +33,16 @@ struct backend
   using midi_out_configuration = alsa_seq::output_configuration;
   using midi_observer_configuration = alsa_seq::observer_configuration;
   static const constexpr auto API = libremidi::API::ALSA_SEQ;
-  static const constexpr auto name = "alsa_seq";
+  static const constexpr std::string_view name = "alsa_seq";
-  static const constexpr auto display_name = "ALSA (sequencer)";
+  static const constexpr std::string_view display_name = "ALSA (sequencer)";
 
   static inline bool available() noexcept
   {
     static const libasound& snd = libasound::instance();
-    return snd.available && snd.seq.available;
+    if (!snd.available || !snd.seq.available)
+      return false;
+
+    return ::access("/dev/snd/seq", F_OK | R_OK | W_OK) == 0;
   }
 };
 

include/libremidi/backends/alsa_seq/config.hpp

@@ -15,7 +15,7 @@ typedef struct snd_seq_addr
 }
 #endif
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 
 // Possible parameters:
@@ -38,6 +38,7 @@ struct input_configuration
   snd_seq_t* context{};
   std::function<bool(const poll_parameters&)> manual_poll;
   std::function<bool(snd_seq_addr_t)> stop_poll;
+  std::chrono::milliseconds poll_period{2};
 
   static constexpr int midi_version = 1;
 };
@@ -56,6 +57,7 @@ struct observer_configuration
   snd_seq_t* context{};
   std::function<bool(const poll_parameters&)> manual_poll;
   std::function<bool(snd_seq_addr_t)> stop_poll;
+  std::chrono::milliseconds poll_period{100};
 
   static constexpr int midi_version = 1;
 };

include/libremidi/backends/alsa_seq/helpers.hpp

@@ -9,7 +9,7 @@
 #include <optional>
 #include <string>
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 struct event_handle
 {
@@ -42,23 +42,39 @@ struct event_handle
   ~event_handle() { snd.seq.free_event(ev); }
 };
 
-namespace
-{
 inline constexpr port_handle seq_to_port_handle(uint64_t client, uint64_t port) noexcept
 {
-  return (client << 32) + port;
+  return (port << 32) + client;
 }
 
 inline constexpr std::pair<int, int> seq_from_port_handle(port_handle p) noexcept
 {
-  int client = p >> 32;
+  int port = p >> 32;
-  int port = p & 0xFFFFFFFF;
+  int client = p & 0xFFFFFFFF;
   return {client, port};
 }
 
+inline void for_all_clients(
+    const libasound& snd, snd_seq_t* seq, const std::function<void(snd_seq_client_info_t&)>& func)
+{
+  snd_seq_client_info_t* cinfo{};
+  snd_seq_client_info_alloca(&cinfo);
+  snd_seq_port_info_t* pinfo{};
+  snd_seq_port_info_alloca(&pinfo);
+
+  snd.seq.client_info_set_client(cinfo, -1);
+  while (snd.seq.query_next_client(seq, cinfo) >= 0)
+  {
+    int client = snd.seq.client_info_get_client(cinfo);
+    if (client == 0)
+      continue;
+    func(*cinfo);
+  }
+}
+
 inline void for_all_ports(
     const libasound& snd, snd_seq_t* seq,
-    std::function<void(snd_seq_client_info_t&, snd_seq_port_info_t&)> func)
+    const std::function<void(snd_seq_client_info_t&, snd_seq_port_info_t&)>& func)
 {
   snd_seq_client_info_t* cinfo{};
   snd_seq_client_info_alloca(&cinfo);
@@ -82,6 +98,21 @@ inline void for_all_ports(
   }
 }
 
+inline void for_all_ports(
+    const libasound& snd, snd_seq_t* seq, int client,
+    const std::function<void(snd_seq_port_info_t&)>& func)
+{
+  snd_seq_port_info_t* pinfo{};
+  snd_seq_port_info_alloca(&pinfo);
+
+  snd.seq.port_info_set_client(pinfo, client);
+  snd.seq.port_info_set_port(pinfo, -1);
+  while (snd.seq.query_next_port(seq, pinfo) >= 0)
+  {
+    func(*pinfo);
+  }
+}
+
 // This function is used to count or get the pinfo structure for a given port
 // number.
 inline unsigned int iterate_port_info(
@@ -125,7 +156,6 @@ inline unsigned int iterate_port_info(
     return count;
   return 0;
 }
-}
 
 // A structure to hold variables related to the ALSA API
 // implementation.
@@ -159,15 +189,15 @@ struct alsa_data
         snd.seq.set_client_name(seq, configuration.client_name.data());
 
 #if __has_include(<alsa/ump.h>)
-      if (snd.seq.ump.set_client_midi_version)
+      if (snd.seq.set_client_midi_version)
       {
         switch (configuration.midi_version)
         {
           case 1:
-            snd.seq.ump.set_client_midi_version(seq, SND_SEQ_CLIENT_LEGACY_MIDI);
+            snd.seq.set_client_midi_version(seq, SND_SEQ_CLIENT_LEGACY_MIDI);
             break;
           case 2:
-            snd.seq.ump.set_client_midi_version(seq, SND_SEQ_CLIENT_UMP_MIDI_2_0);
+            snd.seq.set_client_midi_version(seq, SND_SEQ_CLIENT_UMP_MIDI_2_0);
             break;
         }
       }
@@ -177,18 +207,20 @@ struct alsa_data
     }
   }
 
-  void set_client_name(std::string_view clientName)
+  stdx::error set_client_name(std::string_view clientName)
   {
-    snd.seq.set_client_name(seq, clientName.data());
+    int ret = snd.seq.set_client_name(seq, clientName.data());
+    return from_errc(ret);
   }
 
-  void set_port_name(std::string_view portName)
+  stdx::error set_port_name(std::string_view portName)
   {
     snd_seq_port_info_t* pinfo;
     snd_seq_port_info_alloca(&pinfo);
     snd.seq.get_port_info(seq, vport, pinfo);
     snd.seq.port_info_set_name(pinfo, portName.data());
-    snd.seq.set_port_info(seq, vport, pinfo);
+    int ret = snd.seq.set_port_info(seq, vport, pinfo);
+    return from_errc(ret);
   }
 
   unsigned int get_port_count(int caps) const
@@ -209,9 +241,9 @@ struct alsa_data
     // snd.seq.port_info_set_port(src_pinfo, port);
 
     // {
-    //   self.template error<invalid_parameter_error>(
+    //   self.libremidi_handle_error(
     //       self.configuration,
-    //       "alsa::get_port_info: invalid 'portNumber' argument: " + std::to_string(portNumber));
+    //       "invalid 'portNumber' argument: " + std::to_string(portNumber));
     //   return {};
     // }
     snd_seq_addr_t addr;
@@ -270,8 +302,7 @@ struct alsa_data
     // Make subscription
     if (int err = snd.seq.port_subscribe_malloc(&this->subscription); err < 0)
     {
-      self.template error<driver_error>(
+      self.libremidi_handle_error(self.configuration, "ALSA error allocation port subscription.");
-          self.configuration, "create_connection: ALSA error allocation port subscription.");
       return err;
     }
 

include/libremidi/backends/alsa_seq/midi_in.hpp

@@ -5,7 +5,7 @@
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/midi_stream_decoder.hpp>
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 struct dummy_processing
 {
@@ -17,7 +17,7 @@ using midi_in_base
     = std::conditional_t<ConfigurationImpl::midi_version == 1, midi1::in_api, midi2::in_api>;
 template <typename ConfigurationImpl>
 using midi_in_processing = std::conditional_t<
-    ConfigurationImpl::midi_version == 1, midi1::input_state_machine, dummy_processing>;
+    ConfigurationImpl::midi_version == 1, midi1::input_state_machine, midi2::input_state_machine>;
 
 template <typename ConfigurationBase, typename ConfigurationImpl>
 class midi_in_impl
@@ -55,9 +55,9 @@ public:
   {
     if (init_client(configuration) < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_in_alsa::initialize: error creating ALSA sequencer client "
+          "error creating ALSA sequencer client "
           "object.");
       return;
     }
@@ -80,8 +80,7 @@ public:
       int result = snd.midi.event_new(0, &coder);
       if (result < 0)
       {
-        error<driver_error>(
+        libremidi_handle_error(this->configuration, "error during snd_midi_event_new.");
-            this->configuration, "midi_in_alsa::initialize: error during snd_midi_event_new.");
         return;
       }
       snd.midi.event_init(coder);
@@ -105,7 +104,13 @@ public:
       snd.seq.close(this->seq);
   }
 
-  libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_SEQ; }
+  libremidi::API get_current_api() const noexcept override
+  {
+    if constexpr (ConfigurationImpl::midi_version == 1)
+      return libremidi::API::ALSA_SEQ;
+    else
+      return libremidi::API::ALSA_SEQ_UMP;
+  }
 
   [[nodiscard]] int create_port(std::string_view portName)
   {
@@ -157,14 +162,13 @@ public:
 
     if (int ret = create_port(portName); ret < 0)
     {
-      error<driver_error>(configuration, "midi_in_alsa::create_port: ALSA error creating port.");
+      libremidi_handle_error(configuration, "ALSA error creating port.");
       return ret;
     }
 
     if (int ret = connect_port(*source); ret < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(configuration, "ALSA error making port connection.");
-          configuration, "midi_in_alsa::create_port: ALSA error making port connection.");
       return ret;
     }
 
@@ -184,63 +188,16 @@ public:
     return 0;
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
     unsubscribe();
     stop_queue();
+    return stdx::error{};
   }
 
-  void set_client_name(std::string_view clientName) override
+  stdx::error set_port_name(std::string_view portName) override
   {
-    alsa_data::set_client_name(clientName);
+    return alsa_data::set_port_name(portName);
-  }
-
-  void set_port_name(std::string_view portName) override { alsa_data::set_port_name(portName); }
-
-protected:
-  void set_timestamp(const auto& ev, auto& msg) noexcept
-  {
-    static constexpr int64_t nanos = 1e9;
-    switch (configuration.timestamps)
-    {
-      case timestamp_mode::NoTimestamp:
-        msg.timestamp = 0;
-        return;
-      case timestamp_mode::Relative: {
-        const auto t1 = static_cast<int64_t>(ev.time.time.tv_sec) * nanos
-                        + static_cast<int64_t>(ev.time.time.tv_nsec);
-        const auto t0 = static_cast<int64_t>(last_time.tv_sec) * nanos
-                        + static_cast<int64_t>(last_time.tv_nsec);
-        const auto time = t1 - t0;
-
-        last_time = ev.time.time;
-
-        if (this->firstMessage == true)
-        {
-          this->firstMessage = false;
-          msg.timestamp = 0;
-        }
-        else
-        {
-          msg.timestamp = time;
-        }
-        return;
-      }
-      case timestamp_mode::Absolute: {
-        msg.timestamp = ev.time.time.tv_sec * nanos + ev.time.time.tv_nsec;
-        break;
-      }
-      case timestamp_mode::Custom: {
-        msg.timestamp
-            = configuration.get_timestamp(ev.time.time.tv_sec * nanos + ev.time.time.tv_nsec);
-        break;
-      }
-      case timestamp_mode::SystemMonotonic: {
-        namespace clk = std::chrono;
-        msg.timestamp = system_ns();
-        break;
-      }
-    }
   }
 
   timestamp absolute_timestamp() const noexcept override
@@ -250,7 +207,7 @@ protected:
         .count();
   }
 
-  int process_event(const snd_seq_event_t& ev)
+  int64_t process_event(const snd_seq_event_t& ev)
   {
     if constexpr (ConfigurationImpl::midi_version == 1)
     {
@@ -296,19 +253,21 @@ protected:
     return 0;
   }
 
-  int process_events()
+  int64_t process_events()
   {
     if constexpr (ConfigurationImpl::midi_version == 1)
     {
       snd_seq_event_t* ev{};
       event_handle handle{snd};
-      int result = 0;
+      int64_t result = 0;
-      while ((result = snd.seq.event_input(seq, &ev)) > 0)
+      if ((result = snd.seq.event_input(seq, &ev)) > 0)
       {
         handle.reset(ev);
-        if (int err = process_event(*ev); err < 0)
+        if (auto err = process_event(*ev); err < 0)
+        {
           return err;
         }
+      }
       return result;
     }
     else
@@ -346,11 +305,17 @@ protected:
       }
     }
 
-    // MIDI 2 : no decoder, we can just send the UMP data directly, yay
+    static constexpr timestamp_backend_info timestamp_info{
-    libremidi::ump ump;
+        .has_absolute_timestamps = true,
-    std::memcpy(ump.data, ev.ump, sizeof(ev.ump));
+        .absolute_is_monotonic = false,
-    set_timestamp(ev, ump);
+        .has_samples = false,
-    configuration.on_message(std::move(ump));
+    };
+    const auto to_ns = [ts = ev.time.time] {
+      return static_cast<int64_t>(ts.tv_sec) * 1'000'000'000 + static_cast<int64_t>(ts.tv_nsec);
+    };
+
+    m_processing.on_bytes_multi(
+        {ev.ump, ev.ump + 4}, m_processing.template timestamp<timestamp_info>(to_ns, 0));
     return 0;
   }
 
@@ -370,7 +335,6 @@ protected:
 #endif
 
   int queue_id{}; // an input queue is needed to get timestamped events
-  snd_seq_real_time_t last_time{};
 
   // Only needed for midi 1
   std::vector<unsigned char> decoding_buffer = std::vector<unsigned char>(4096);
@@ -384,89 +348,96 @@ public:
   midi_in_alsa_threaded(ConfigurationBase&& conf, ConfigurationImpl&& apiconf)
       : midi_in_impl<ConfigurationBase, ConfigurationImpl>{std::move(conf), std::move(apiconf)}
   {
-    if (this->termination_event < 0)
+    if (this->m_termination_event < 0)
     {
-      this->template error<driver_error>(
+      this->libremidi_handle_error(this->configuration, "error creating eventfd.");
-          this->configuration, "midi_in_alsa::initialize: error creating eventfd.");
+      return;
-    }
     }
 
-  ~midi_in_alsa_threaded() { this->close_port(); }
+    this->client_open_ = stdx::error{};
+  }
+
+  ~midi_in_alsa_threaded()
+  {
+    midi_in_alsa_threaded::close_port();
+    this->client_open_ = std::errc::not_connected;
+  }
 
 private:
-  bool open_port(const input_port& pt, std::string_view local_port_name) override
+  stdx::error open_port(const input_port& pt, std::string_view local_port_name) override
   {
     if (int err = this->init_port(this->to_address(pt), local_port_name); err < 0)
-      return false;
+      return from_errc(err);
 
-    if (!start_thread())
+    return this->start_thread();
-      return false;
-
-    return true;
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
     if (int err = this->init_virtual_port(portName); err < 0)
-      return false;
+      return from_errc(err);
 
-    if (!this->start_thread())
+    return this->start_thread();
-      return false;
-    return true;
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
-    midi_in_impl<ConfigurationBase, ConfigurationImpl>::close_port();
+    // FIXME shouldn't we always close the thread
+    auto err = midi_in_impl<ConfigurationBase, ConfigurationImpl>::close_port();
 
     stop_thread();
+
+    return err;
   }
 
-  [[nodiscard]] int start_thread()
+  [[nodiscard]] stdx::error start_thread()
   {
     try
     {
-      this->thread = std::thread([this] { thread_handler(); });
+      this->m_thread = std::thread([this] { thread_handler(); });
+      return stdx::error{};
     }
     catch (const std::system_error& e)
     {
       using namespace std::literals;
       this->unsubscribe();
 
-      this->template error<thread_error>(
+      this->libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error starting MIDI input thread: "s + e.what());
-          "midi_in_alsa::start_thread: error starting MIDI input thread: "s + e.what());
+      return e.code();
-      return false;
     }
-    return true;
   }
 
-  void stop_thread()
+  stdx::error stop_thread()
   {
-    termination_event.notify();
+    m_termination_event.notify();
 
-    if (this->thread.joinable())
+    if (this->m_thread.joinable())
-      this->thread.join();
+      this->m_thread.join();
 
-    termination_event.consume();
+    m_termination_event.consume();
+    return stdx::error{};
   }
 
   void thread_handler()
   {
     int poll_fd_count = alsa_data::snd.seq.poll_descriptors_count(this->seq, POLLIN) + 1;
     auto poll_fds = (struct pollfd*)alloca(poll_fd_count * sizeof(struct pollfd));
-    poll_fds[0] = this->termination_event;
+    poll_fds[0] = this->m_termination_event;
     alsa_data::snd.seq.poll_descriptors(this->seq, poll_fds + 1, poll_fd_count - 1, POLLIN);
 
+    const auto period
+        = std::chrono::duration_cast<std::chrono::milliseconds>(this->configuration.poll_period)
+              .count();
     for (;;)
     {
       if (alsa_data::snd.seq.event_input_pending(this->seq, 1) == 0)
       {
         // No data pending
-        if (poll(poll_fds, poll_fd_count, -1) >= 0)
+        if (poll(poll_fds, poll_fd_count, static_cast<int32_t>(period)) >= 0)
         {
           // We got our stop-thread signal
-          if (termination_event.ready(poll_fds[0]))
+          if (m_termination_event.ready(poll_fds[0]))
           {
             break;
           }
@@ -474,7 +445,7 @@ private:
         continue;
       }
 
-      int res{};
+      int64_t res{};
       if constexpr (ConfigurationImpl::midi_version == 1)
       {
         res = this->process_events();
@@ -486,17 +457,13 @@ private:
       }
 #endif
 
-      (void)res;
-#if defined(__LIBREMIDI_DEBUG__)
       if (res < 0)
-        std::cerr << "midi_in_alsa::thread_handler: MIDI input error: " << snd.strerror(res)
+        LIBREMIDI_LOG("MIDI input error: ", this->snd.strerror(res));
-                  << "\n";
-#endif
     }
   }
 
-  std::thread thread{};
+  std::thread m_thread{};
-  eventfd_notifier termination_event{};
+  eventfd_notifier m_termination_event{};
 };
 
 template <typename ConfigurationBase, typename ConfigurationImpl>
@@ -525,38 +492,40 @@ public:
     return 0;
   }
 
-  ~midi_in_alsa_manual() { this->close_port(); }
+  ~midi_in_alsa_manual() { midi_in_alsa_manual::close_port(); }
 
-  bool open_port(const input_port& pt, std::string_view local_port_name) override
+  stdx::error open_port(const input_port& pt, std::string_view local_port_name) override
   {
     if (int err = this->init_port(this->to_address(pt), local_port_name); err < 0)
-      return false;
+      return from_errc(err);
 
     if (int err = init_callback(); err < 0)
-      return false;
+      return from_errc(err);
-    return true;
+
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view name) override
+  stdx::error open_virtual_port(std::string_view name) override
   {
     if (int err = this->init_virtual_port(name); err < 0)
-      return false;
+      return from_errc(err);
 
     if (int err = init_callback(); err < 0)
-      return false;
+      return from_errc(err);
-    return true;
+
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override
   {
     this->configuration.stop_poll(this->vaddr);
 
-    midi_in_impl<ConfigurationBase, ConfigurationImpl>::close_port();
+    return midi_in_impl<ConfigurationBase, ConfigurationImpl>::close_port();
   }
 };
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<midi_in_api>

include/libremidi/backends/alsa_seq/midi_out.hpp

@@ -3,7 +3,7 @@
 #include <libremidi/backends/alsa_seq/helpers.hpp>
 #include <libremidi/detail/midi_out.hpp>
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 
 class midi_out_impl final
@@ -23,22 +23,21 @@ public:
   {
     if (init_client(configuration) < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_in_alsa::initialize: error creating ALSA sequencer client "
+          "error creating ALSA sequencer client "
           "object.");
       return;
     }
 
-    if (snd.midi.event_new(this->bufferSize, &this->coder) < 0)
+    if (snd.midi.event_new(this->m_bufferSize, &this->coder) < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error initializing MIDI event parser.");
-          this->configuration,
-          "midi_out_alsa::initialize: error initializing MIDI event "
-          "parser.");
       return;
     }
     snd.midi.event_init(this->coder);
+
+    this->client_open_ = stdx::error{};
   }
 
   ~midi_out_impl() override
@@ -54,6 +53,8 @@ public:
 
     if (!configuration.context)
       snd.seq.close(this->seq);
+
+    client_open_ = std::errc::not_connected;
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_SEQ; }
@@ -65,68 +66,69 @@ public:
         SND_SEQ_PORT_TYPE_MIDI_GENERIC | SND_SEQ_PORT_TYPE_APPLICATION, std::nullopt);
   }
 
-  bool open_port(const output_port& p, std::string_view portName) override
+  stdx::error open_port(const output_port& p, std::string_view portName) override
   {
-    unsigned int nSrc = this->get_port_count(SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE);
+    unsigned int n_src
-    if (nSrc < 1)
+        = this->get_port_count(SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE);
+    if (n_src < 1)
     {
-      error<no_devices_found_error>(
+      libremidi_handle_error(this->configuration, "no MIDI output sources found!");
-          this->configuration, "midi_out_alsa::open_port: no MIDI output sources found!");
+      return make_error_code(std::errc::no_such_device);
-      return false;
     }
 
     auto sink = get_port_info(p);
     if (!sink)
-      return false;
+      return std::errc::invalid_argument;
 
     if (int err = create_port(portName); err < 0)
     {
-      error<driver_error>(configuration, "midi_out_alsa::create_port: ALSA error creating port.");
+      libremidi_handle_error(configuration, "ALSA error creating port.");
-      return false;
+      return from_errc(err);
     }
 
     snd_seq_addr_t source{
         .client = (unsigned char)snd.seq.client_id(this->seq), .port = (unsigned char)this->vport};
     if (int err = create_connection(*this, source, *sink, true); err < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(configuration, "ALSA error making port connection.");
-          configuration, "midi_out_alsa::create_port: ALSA error making port connection.");
+      return from_errc(err);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
     if (int err = create_port(portName); err < 0)
-      return false;
+      return from_errc(err);
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override { unsubscribe(); }
+  stdx::error close_port() override
-
-  void set_client_name(std::string_view clientName) override
   {
-    alsa_data::set_client_name(clientName);
+    unsubscribe();
+    return stdx::error{};
   }
 
-  void set_port_name(std::string_view portName) override { alsa_data::set_port_name(portName); }
+  stdx::error set_port_name(std::string_view portName) override
+  {
+    return alsa_data::set_port_name(portName);
+  }
 
-  void send_message(const unsigned char* message, std::size_t size) override
+  stdx::error send_message(const unsigned char* message, std::size_t size) override
   {
     int64_t result{};
-    if (size > this->bufferSize)
+    if (size > this->m_bufferSize)
     {
-      this->bufferSize = size;
+      this->m_bufferSize = size;
       result = snd.midi.event_resize_buffer(this->coder, size);
       if (result != 0)
       {
-        error<driver_error>(
+        libremidi_handle_error(
             this->configuration,
-            "midi_out_alsa::send_message: ALSA error resizing MIDI event "
+            "ALSA error resizing MIDI event "
             "buffer.");
-        return;
+        return std::errc::no_buffer_space;
       }
     }
 
@@ -140,18 +142,18 @@ public:
       // FIXME direct is set but snd_seq_event_output_direct is not used...
       snd_seq_ev_set_direct(&ev);
 
-      const int64_t nBytes = size; // signed to avoir potential overflow with size - offset below
+      const int64_t n_bytes = size; // signed to avoir potential overflow with size - offset below
-      result = snd.midi.event_encode(this->coder, message + offset, (long)(nBytes - offset), &ev);
+      result = snd.midi.event_encode(this->coder, message + offset, (long)(n_bytes - offset), &ev);
       if (result < 0)
       {
-        warning(this->configuration, "midi_out_alsa::send_message: event parsing error!");
+        libremidi_handle_warning(this->configuration, "event parsing error!");
-        return;
+        return std::errc::bad_message;
       }
 
       if (ev.type == SND_SEQ_EVENT_NONE)
       {
-        warning(this->configuration, "midi_out_alsa::send_message: incomplete message!");
+        libremidi_handle_warning(this->configuration, "incomplete message!");
-        return;
+        return std::errc::message_size;
       }
 
       offset += result;
@@ -159,16 +161,15 @@ public:
       result = snd.seq.event_output(this->seq, &ev);
       if (result < 0)
       {
-        warning(
+        libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-            this->configuration,
+        return std::errc::io_error;
-            "midi_out_alsa::send_message: error sending MIDI message to port.");
-        return;
       }
     }
     snd.seq.drain_output(this->seq);
+    return stdx::error{};
   }
 
 private:
-  uint64_t bufferSize{32};
+  uint64_t m_bufferSize{32};
 };
 }

include/libremidi/backends/alsa_seq/observer.hpp

@@ -2,30 +2,44 @@
 #include <libremidi/backends/alsa_seq/config.hpp>
 #include <libremidi/backends/alsa_seq/helpers.hpp>
 #include <libremidi/backends/linux/helpers.hpp>
+#include <libremidi/detail/midi_api.hpp>
 #include <libremidi/detail/observer.hpp>
 
 #include <alsa/asoundlib.h>
 
-#include <bitset>
+#if LIBREMIDI_HAS_UDEV
+  #include <libremidi/backends/linux/udev.hpp>
+#endif
+
 #include <map>
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 
+struct client_info
+{
+  std::string client_name;
+  int client_id{};
+  std::optional<int> card{};
+};
+
 struct port_info
 {
   std::string client_name;
   std::string port_name;
   int client{};
   int port{};
-  bool isInput{};
+  bool is_input{};
-  bool isOutput{};
+  bool is_output{};
+  std::optional<int> card{};
+  libremidi::transport_type type{};
 };
 
 template <typename ConfigurationImpl>
 class observer_impl
     : public observer_api
     , public alsa_data
+    , public error_handler
 {
 public:
   struct
@@ -40,7 +54,11 @@ public:
     using namespace std::literals;
     if (int err = init_client(configuration); err < 0)
     {
-      throw driver_error("observer_alsa: snd_seq_open failed");
+      libremidi_handle_error(
+          this->configuration,
+          "error creating ALSA sequencer client "
+          "object.");
+      return;
     }
 
     if (!configuration.has_callbacks())
@@ -65,7 +83,8 @@ public:
           *this, "libremidi-observe", caps, SND_SEQ_PORT_TYPE_APPLICATION, false);
       if (err < 0)
       {
-        throw driver_error("observer: ALSA error creating port.");
+        libremidi_handle_error(this->configuration, "error creating ALSA sequencer port.");
+        return;
       }
     }
 
@@ -75,17 +94,75 @@ public:
           = snd.seq.connect_from(seq, vport, SND_SEQ_CLIENT_SYSTEM, SND_SEQ_PORT_SYSTEM_ANNOUNCE);
       if (err < 0)
       {
-        throw driver_error("observer_alsa: snd_seq_connect_from failed");
+        libremidi_handle_error(this->configuration, "error connecting to ALSA sequencer.");
+        return;
       }
     }
   }
 
-  std::optional<port_info> get_info(int client, int port) const noexcept
+  std::optional<client_info>
+  get_client_info(int client, snd_seq_client_info_t& cinfo) const noexcept
   {
+    client_info p;
+    p.client_id = client;
+
+    if (auto name = snd.seq.client_info_get_name(&cinfo))
+      p.client_name = name;
+
+    if (int card = snd.seq.client_info_get_card(&cinfo); card >= 0)
+      p.card = card;
+
+    return p;
+  }
+
+  std::optional<port_info> get_info(
+      int client, int port, snd_seq_client_info_t& cinfo,
+      snd_seq_port_info_t& pinfo) const noexcept
+  {
+    const auto tp = snd.seq.port_info_get_type(&pinfo);
+    const auto cap = snd.seq.port_info_get_capability(&pinfo);
+    if ((cap & SND_SEQ_PORT_CAP_NO_EXPORT) != 0)
+      return std::nullopt;
+
     port_info p;
     p.client = client;
     p.port = port;
 
+    bool ok = this->configuration.track_any;
+
+    static constexpr auto virtual_port = SND_SEQ_PORT_TYPE_SOFTWARE | SND_SEQ_PORT_TYPE_SYNTHESIZER
+                                         | SND_SEQ_PORT_TYPE_APPLICATION;
+
+    if ((tp & SND_SEQ_PORT_TYPE_HARDWARE) && this->configuration.track_hardware)
+    {
+      p.type = libremidi::transport_type::hardware;
+      ok = true;
+    }
+    else if ((tp & virtual_port) && this->configuration.track_virtual)
+    {
+      p.type = libremidi::transport_type::software;
+      ok = true;
+    }
+    if (!ok)
+      return {};
+
+    if (auto name = snd.seq.client_info_get_name(&cinfo))
+      p.client_name = name;
+
+    if (auto name = snd.seq.port_info_get_name(&pinfo))
+      p.port_name = name;
+
+    if (int card = snd.seq.client_info_get_card(&cinfo); card >= 0)
+      p.card = card;
+
+    p.is_input = (cap & SND_SEQ_PORT_CAP_DUPLEX) | (cap & SND_SEQ_PORT_CAP_READ);
+    p.is_output = (cap & SND_SEQ_PORT_CAP_DUPLEX) | (cap & SND_SEQ_PORT_CAP_WRITE);
+
+    return p;
+  }
+
+  std::optional<port_info> get_info(int client, int port) const noexcept
+  {
     snd_seq_client_info_t* cinfo;
     snd_seq_client_info_alloca(&cinfo);
     if (int err = snd.seq.get_any_client_info(seq, client, cinfo); err < 0)
@@ -96,41 +173,47 @@ public:
     if (int err = snd.seq.get_any_port_info(seq, client, port, pinfo); err < 0)
       return std::nullopt;
 
-    const auto tp = snd.seq.port_info_get_type(pinfo);
+    return get_info(client, port, *cinfo, *pinfo);
-    bool ok = this->configuration.track_any;
-    if ((tp & SND_SEQ_PORT_TYPE_HARDWARE) && this->configuration.track_hardware)
-      ok = true;
-    else if ((tp & SND_SEQ_PORT_TYPE_SOFTWARE) && this->configuration.track_virtual)
-      ok = true;
-    if (!ok)
-      return {};
-
-    if (auto name = snd.seq.client_info_get_name(cinfo))
-      p.client_name = name;
-
-    if (auto name = snd.seq.port_info_get_name(pinfo))
-      p.port_name = name;
-
-    auto cap = snd.seq.port_info_get_capability(pinfo);
-    p.isInput = (cap & SND_SEQ_PORT_CAP_DUPLEX) | (cap & SND_SEQ_PORT_CAP_READ);
-    p.isOutput = (cap & SND_SEQ_PORT_CAP_DUPLEX) | (cap & SND_SEQ_PORT_CAP_WRITE);
-
-    return p;
   }
 
   template <bool Input>
-  auto to_port_info(port_info p) const noexcept
+  auto to_port_info(const port_info& p) const noexcept
       -> std::conditional_t<Input, input_port, output_port>
   {
     static_assert(sizeof(this->seq) <= sizeof(libremidi::client_handle));
     static_assert(sizeof(std::uintptr_t) <= sizeof(libremidi::client_handle));
+
+    container_identifier container{};
+    device_identifier device{};
+    libremidi::transport_type type = p.type;
+    std::string manufacturer;
+    std::string product;
+    std::string serial;
+#if LIBREMIDI_HAS_UDEV
+    if (p.card)
+    {
+      auto res = get_udev_soundcard_info(m_udev, *p.card);
+      container = res.container;
+      device = res.path;
+      type = res.type;
+      manufacturer = res.vendor;
+      product = res.product;
+      serial = res.serial;
+    }
+#endif
     return {
-        {.client = std::uintptr_t(this->seq),
+        {.api = get_current_api(),
+         .client = std::uintptr_t(this->seq),
+         .container = container,
+         .device = device,
          .port = alsa_seq::seq_to_port_handle(p.client, p.port),
-         .manufacturer = "",
+         .manufacturer = manufacturer,
+         .product = product,
+         .serial = serial,
          .device_name = p.client_name,
          .port_name = p.port_name,
-         .display_name = p.port_name}};
+         .display_name = p.port_name,
+         .type = type}};
   }
 
   void init_all_ports()
@@ -158,8 +241,8 @@ public:
         snd, this->seq, [this, &ret](snd_seq_client_info_t& client, snd_seq_port_info_t& port) {
       int clt = snd.seq.client_info_get_client(&client);
       int pt = snd.seq.port_info_get_port(&port);
-          if (auto p = get_info(clt, pt))
+      if (auto p = get_info(clt, pt, client, port))
-            if (p->isInput)
+        if (p->is_input)
           ret.push_back(to_port_info<true>(*p));
     });
     return ret;
@@ -172,8 +255,8 @@ public:
         snd, this->seq, [this, &ret](snd_seq_client_info_t& client, snd_seq_port_info_t& port) {
       int clt = snd.seq.client_info_get_client(&client);
       int pt = snd.seq.port_info_get_port(&port);
-          if (auto p = get_info(clt, pt))
+      if (auto p = get_info(clt, pt, client, port))
-            if (p->isOutput)
+        if (p->is_output)
           ret.push_back(to_port_info<false>(*p));
     });
     return ret;
@@ -188,13 +271,13 @@ public:
     if (p.client == snd.seq.client_id(seq))
       return;
 
-    knownClients_[{p.client, p.port}] = p;
+    m_knownClients[{p.client, p.port}] = p;
-    if (p.isInput && configuration.input_added)
+    if (p.is_input && configuration.input_added)
     {
       configuration.input_added(to_port_info<true>(p));
     }
 
-    if (p.isOutput && configuration.output_added)
+    if (p.is_output && configuration.output_added)
     {
       configuration.output_added(to_port_info<false>(p));
     }
@@ -202,37 +285,61 @@ public:
 
   void unregister_port(int client, int port)
   {
-    auto it = knownClients_.find({client, port});
+    auto it = m_knownClients.find({client, port});
-    if (it != knownClients_.end())
+    if (it != m_knownClients.end())
     {
       auto p = it->second;
-      knownClients_.erase(it);
+      m_knownClients.erase(it);
 
-      if (p.isInput && configuration.input_removed)
+      if (p.is_input && configuration.input_removed)
       {
         configuration.input_removed(to_port_info<true>(p));
       }
 
-      if (p.isOutput && configuration.output_removed)
+      if (p.is_output && configuration.output_removed)
       {
         configuration.output_removed(to_port_info<false>(p));
       }
     }
   }
 
-  void handle_event(const snd_seq_event_t& ev)
+  void handle_event_direct(const snd_seq_event_t& ev)
   {
     switch (ev.type)
     {
+      case SND_SEQ_EVENT_CLIENT_START: {
+        // TODO
+        break;
+      }
+      case SND_SEQ_EVENT_CLIENT_EXIT: {
+        // TODO
+        break;
+      }
+      case SND_SEQ_EVENT_CLIENT_CHANGE: {
+        // TODO
+        break;
+      }
+#if LIBREMIDI_ALSA_HAS_UMP_SEQ_EVENTS
+      case SND_SEQ_EVENT_UMP_EP_CHANGE: {
+        // TODO
+        break;
+      }
+      case SND_SEQ_EVENT_UMP_BLOCK_CHANGE: {
+        // TODO
+        break;
+      }
+#endif
       case SND_SEQ_EVENT_PORT_START: {
-        register_port(ev.data.addr.client, ev.data.addr.port);
+        this->register_port(ev.data.addr.client, ev.data.addr.port);
         break;
       }
       case SND_SEQ_EVENT_PORT_EXIT: {
-        unregister_port(ev.data.addr.client, ev.data.addr.port);
+        this->unregister_port(ev.data.addr.client, ev.data.addr.port);
         break;
       }
       case SND_SEQ_EVENT_PORT_CHANGE:
+        // TODO
+        break;
       default:
         break;
     }
@@ -251,7 +358,11 @@ public:
   }
 
 private:
-  std::map<std::pair<int, int>, port_info> knownClients_;
+  std::map<std::pair<int, int>, port_info> m_knownClients;
+
+#if LIBREMIDI_HAS_UDEV
+  udev_helper m_udev{};
+#endif
 };
 
 template <typename ConfigurationImpl>
@@ -263,35 +374,87 @@ public:
   {
     // Create relevant descriptors
     auto& snd = alsa_data::snd;
-    const auto N = snd.seq.poll_descriptors_count(this->seq, POLLIN);
+
-    descriptors_.resize(N + 1);
+    // 1. Descriptor count
-    snd.seq.poll_descriptors(this->seq, descriptors_.data(), N, POLLIN);
+    const auto n = snd.seq.poll_descriptors_count(this->seq, POLLIN);
-    descriptors_.back() = this->termination_event;
+    int total_descriptors = n;
+    total_descriptors++; // eventfd for terminating the thread
+
+    // 2. Create storage
+    descriptors.resize(total_descriptors);
+
+    // 3. Store descriptors
+    snd.seq.poll_descriptors(this->seq, descriptors.data(), n, POLLIN);
+    descriptors[n] = this->termination_event;
 
     // Start the listening thread
-    thread = std::thread{[this] {
+    thread = std::thread{[this, n] {
       auto& snd = alsa_data::snd;
+      const auto period
+          = std::chrono::duration_cast<std::chrono::milliseconds>(this->configuration.poll_period)
+                .count();
       for (;;)
       {
-        int err = poll(descriptors_.data(), descriptors_.size(), -1);
+        int err = poll(descriptors.data(), descriptors.size(), static_cast<int32_t>(period));
         if (err >= 0)
         {
           // We got our stop-thread signal
-          if (descriptors_.back().revents & POLLIN)
+          if (descriptors[n].revents & POLLIN)
             break;
 
+          // Put ALSA event in our queue
           snd_seq_event_t* ev{};
           event_handle handle{snd};
           while (snd.seq.event_input(this->seq, &ev) >= 0)
           {
             handle.reset(ev);
-            this->handle_event(*ev);
+            this->handle_event_delayed(*ev);
+          }
+
+          // Process the events in a deferred way.
+          // This is because udev takes some milliseconds to populate its field after a
+          // port was added
+          auto tm = std::chrono::steady_clock::now();
+          for (auto it = queued_events.begin(); it != queued_events.end();)
+          {
+            if ((tm - it->second) >= this->configuration.poll_period)
+            {
+              this->handle_event_direct(it->first);
+              it = queued_events.erase(it);
+            }
+            else
+            {
+              break;
+            }
           }
         }
       }
     }};
   }
 
+  void handle_event_delayed(const snd_seq_event_t& ev)
+  {
+    switch (ev.type)
+    {
+      case SND_SEQ_EVENT_CLIENT_START:
+      case SND_SEQ_EVENT_CLIENT_EXIT:
+      case SND_SEQ_EVENT_CLIENT_CHANGE:
+
+#if LIBREMIDI_ALSA_HAS_UMP_SEQ_EVENTS
+      case SND_SEQ_EVENT_UMP_EP_CHANGE:
+      case SND_SEQ_EVENT_UMP_BLOCK_CHANGE:
+#endif
+
+      case SND_SEQ_EVENT_PORT_START:
+      case SND_SEQ_EVENT_PORT_EXIT:
+      case SND_SEQ_EVENT_PORT_CHANGE:
+        queued_events.emplace_back(ev, std::chrono::steady_clock::now());
+        break;
+      default:
+        break;
+    }
+  }
+
   ~observer_threaded()
   {
     termination_event.notify();
@@ -302,7 +465,8 @@ public:
 
   eventfd_notifier termination_event{};
   std::thread thread;
-  std::vector<pollfd> descriptors_;
+  std::vector<pollfd> descriptors;
+  std::vector<std::pair<snd_seq_event_t, std::chrono::steady_clock::time_point>> queued_events;
 };
 
 template <typename ConfigurationImpl>
@@ -314,7 +478,7 @@ public:
   {
     this->configuration.manual_poll(
         poll_parameters{.addr = this->vaddr, .callback = [this](const auto& v) {
-                          this->handle_event(v);
+      this->handle_event_direct(v);
       return 0;
     }});
   }
@@ -323,7 +487,7 @@ public:
 };
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<observer_api>

include/libremidi/backends/alsa_seq/shared_handler.hpp

@@ -9,7 +9,7 @@
 
   #include <variant>
 
-namespace libremidi::alsa_seq
+NAMESPACE_LIBREMIDI::alsa_seq
 {
 
 struct shared_handler : public libremidi::shared_context
@@ -61,7 +61,7 @@ struct shared_handler : public libremidi::shared_context
   {
     auto clt = std::make_shared<shared_handler>(client_name);
 
-    auto cb = [client = std::weak_ptr{clt}](const libremidi::alsa_seq::poll_parameters& params) {
+    auto cb = [client = std::weak_ptr{clt}](libremidi::alsa_seq::poll_parameters params) {
       if (auto clt = client.lock())
       {
         clt->events.push(
@@ -74,8 +74,7 @@ struct shared_handler : public libremidi::shared_context
     auto stop_cb = [client = std::weak_ptr{clt}](snd_seq_addr_t id) {
       if (auto clt = client.lock())
       {
-        clt->events.push(
+        clt->events.push({.type = shared_handler::event_type::callback_removed, .payload = id});
-            {.type = shared_handler::event_type::callback_removed, .payload = std::move(id)});
         clt->queue_event.notify();
       }
       return true;
@@ -128,13 +127,13 @@ struct shared_handler : public libremidi::shared_context
           {
             case callback_added: {
               auto [addr, cb]
-                  = std::move(*std::get_if<libremidi::alsa_seq::poll_parameters>(&ev.payload));
+                  = std::move(*get_if<libremidi::alsa_seq::poll_parameters>(&ev.payload));
               addresses.push_back(addr);
               callbacks.push_back(std::move(cb));
               break;
             }
             case callback_removed:
-              auto addr = std::move(*std::get_if<snd_seq_addr_t>(&ev.payload));
+              auto addr = *get_if<snd_seq_addr_t>(&ev.payload);
               if (auto index = index_of_address(addr); index >= 0)
               {
                 addresses.erase(addresses.begin() + index);
@@ -146,15 +145,14 @@ struct shared_handler : public libremidi::shared_context
       }
 
       // Look for who's ready
-      for (int64_t i = 0, N = std::ssize(fds) - 2; i < N; i++)
+      for (int64_t i = 0, n = std::ssize(fds) - 2; i < n; i++)
       {
         if (fds[i].revents & POLLIN)
         {
           // Read alsa event
           snd_seq_event_t* ev{};
           event_handle handle{snd};
-          int result = 0;
+          while (snd.seq.event_input(client, &ev) > 0)
-          while ((result = snd.seq.event_input(client, &ev)) > 0)
           {
             handle.reset(ev);
 
@@ -181,7 +179,7 @@ struct shared_handler : public libremidi::shared_context
   struct event
   {
     event_type type;
-    std::variant<libremidi::alsa_seq::poll_parameters, snd_seq_addr_t> payload;
+    libremidi_variant_alias::variant<libremidi::alsa_seq::poll_parameters, snd_seq_addr_t> payload;
   };
 
   snd_seq_t* client{};

include/libremidi/backends/alsa_seq_ump.hpp

@@ -5,7 +5,11 @@
 #include <libremidi/backends/alsa_seq_ump/config.hpp>
 #include <libremidi/backends/alsa_seq_ump/midi_out.hpp>
 
-namespace libremidi
+#include <unistd.h>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<observer_api>
@@ -38,7 +42,7 @@ inline std::unique_ptr<midi_in_api> make<
 
 }
 
-namespace libremidi::alsa_seq_ump
+NAMESPACE_LIBREMIDI::alsa_seq_ump
 {
 struct backend
 {
@@ -50,13 +54,16 @@ struct backend
   using midi_out_configuration = alsa_seq_ump::output_configuration;
   using midi_observer_configuration = alsa_seq_ump::observer_configuration;
   static const constexpr auto API = libremidi::API::ALSA_SEQ_UMP;
-  static const constexpr auto name = "alsa_seq_ump";
+  static const constexpr std::string_view name = "alsa_seq_ump";
-  static const constexpr auto display_name = "ALSA (sequencer, UMP)";
+  static const constexpr std::string_view display_name = "ALSA (sequencer, UMP)";
 
   static inline bool available() noexcept
   {
     static const libasound& snd = libasound::instance();
-    return snd.available && snd.seq.available && snd.seq.ump.available && snd.ump.available;
+    if (!snd.available || !snd.seq.available || !snd.seq.ump.available || !snd.ump.available)
+      return false;
+
+    return ::access("/dev/snd/seq", F_OK | R_OK | W_OK) == 0;
   }
 };
 }

include/libremidi/backends/alsa_seq_ump/config.hpp

@@ -11,7 +11,7 @@ extern "C" {
 typedef struct snd_seq_ump_event snd_seq_ump_event_t;
 }
 
-namespace libremidi::alsa_seq_ump
+NAMESPACE_LIBREMIDI::alsa_seq_ump
 {
 
 struct poll_parameters
@@ -28,6 +28,7 @@ struct input_configuration
   snd_seq_t* context{};
   std::function<bool(const poll_parameters&)> manual_poll;
   std::function<bool(snd_seq_addr_t)> stop_poll;
+  std::chrono::milliseconds poll_period{2};
 
   static constexpr int midi_version = 2;
 };
@@ -46,6 +47,7 @@ struct observer_configuration
   snd_seq_t* context{};
   std::function<bool(const libremidi::alsa_seq::poll_parameters&)> manual_poll;
   std::function<bool(snd_seq_addr_t)> stop_poll;
+  std::chrono::milliseconds poll_period{100};
 
   static constexpr int midi_version = 2;
 };

include/libremidi/backends/alsa_seq_ump/midi_out.hpp

@@ -5,7 +5,7 @@
 #include <libremidi/detail/midi_out.hpp>
 #include <libremidi/detail/ump_stream.hpp>
 
-namespace libremidi::alsa_seq_ump
+NAMESPACE_LIBREMIDI::alsa_seq_ump
 {
 
 class midi_out_impl final
@@ -27,22 +27,14 @@ public:
     assert(snd.seq.ump.available);
     if (init_client(configuration) < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_in_alsa::initialize: error creating ALSA sequencer client "
+          "error creating ALSA sequencer client "
           "object.");
       return;
     }
 
-    if (snd.midi.event_new(this->bufferSize, &this->coder) < 0)
+    this->client_open_ = stdx::error{};
-    {
-      error<driver_error>(
-          this->configuration,
-          "midi_out_alsa::initialize: error initializing MIDI event "
-          "parser.");
-      return;
-    }
-    snd.midi.event_init(this->coder);
   }
 
   ~midi_out_impl() override
@@ -53,14 +45,14 @@ public:
     // Cleanup.
     if (this->vport >= 0)
       snd.seq.delete_port(this->seq, this->vport);
-    if (this->coder)
-      snd.midi.event_free(this->coder);
 
     if (!configuration.context)
       snd.seq.close(this->seq);
+
+    client_open_ = std::errc::not_connected;
   }
 
-  libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_SEQ; }
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::ALSA_SEQ_UMP; }
 
   [[nodiscard]] int create_port(std::string_view portName)
   {
@@ -70,55 +62,56 @@ public:
         SND_SEQ_PORT_TYPE_MIDI_GENERIC | SND_SEQ_PORT_TYPE_APPLICATION, std::nullopt);
   }
 
-  bool open_port(const output_port& p, std::string_view portName) override
+  stdx::error open_port(const output_port& p, std::string_view portName) override
   {
-    unsigned int nSrc = this->get_port_count(SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE);
+    unsigned int n_src
-    if (nSrc < 1)
+        = this->get_port_count(SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE);
+    if (n_src < 1)
     {
-      error<no_devices_found_error>(
+      libremidi_handle_error(this->configuration, "no MIDI output sources found!");
-          this->configuration, "midi_out_alsa::open_port: no MIDI output sources found!");
+      return make_error_code(std::errc::no_such_device);
-      return false;
     }
 
     auto sink = get_port_info(p);
     if (!sink)
-      return false;
+      return std::errc::invalid_argument;
 
     if (int err = create_port(portName); err < 0)
     {
-      error<driver_error>(configuration, "midi_out_alsa::create_port: ALSA error creating port.");
+      libremidi_handle_error(configuration, "ALSA error creating port.");
-      return false;
+      return from_errc(err);
     }
 
     snd_seq_addr_t source{
         .client = (unsigned char)snd.seq.client_id(this->seq), .port = (unsigned char)this->vport};
     if (int err = create_connection(*this, source, *sink, true); err < 0)
     {
-      error<driver_error>(
+      libremidi_handle_error(configuration, "ALSA error making port connection.");
-          configuration, "midi_out_alsa::create_port: ALSA error making port connection.");
+      return from_errc(err);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
     if (int err = create_port(portName); err < 0)
-      return false;
+      return from_errc(err);
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override { unsubscribe(); }
+  stdx::error close_port() override
-
-  void set_client_name(std::string_view clientName) override
   {
-    alsa_data::set_client_name(clientName);
+    unsubscribe();
+    return stdx::error{};
   }
 
-  void set_port_name(std::string_view portName) override { alsa_data::set_port_name(portName); }
+  stdx::error set_port_name(std::string_view portName) override
+  {
+    return alsa_data::set_port_name(portName);
+  }
 
-  void send_ump(const uint32_t* ump_stream, std::size_t count) override
+  stdx::error send_ump(const uint32_t* ump_stream, std::size_t count) override
   {
     snd_seq_ump_event_t ev;
 
@@ -128,24 +121,21 @@ public:
     snd_seq_ev_set_subs(&ev);
     snd_seq_ev_set_direct(&ev);
 
-    auto write_func = [this, &ev](const uint32_t* ump, int64_t bytes) {
+    auto write_func = [this, &ev](const uint32_t* ump, int64_t bytes) -> std::errc {
       std::memcpy(ev.ump, ump, bytes);
-      const int result = snd.seq.ump.event_output_direct(this->seq, &ev);
+      const int ret = snd.seq.ump.event_output_direct(this->seq, &ev);
-      if (result < 0)
+      if (ret < 0)
       {
-        warning(
+        libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-            this->configuration,
+        return static_cast<std::errc>(-ret);
-            "midi_out_alsa::send_message: error sending MIDI message to port.");
-        return libremidi::segmentation_error::other;
       }
-      return libremidi::segmentation_error::no_error;
+      static_assert(std::errc{0} == std::errc{});
+      return std::errc{};
     };
     segment_ump_stream(ump_stream, count, write_func, []() { });
 
     snd.seq.drain_output(this->seq);
+    return stdx::error{};
   }
-
-private:
-  unsigned int bufferSize{32};
 };
 }

include/libremidi/backends/android/android.hpp

@@ -0,0 +1,33 @@
+#pragma once
+#include <libremidi/backends/android/config.hpp>
+#include <libremidi/backends/android/midi_in.hpp>
+#include <libremidi/backends/android/midi_out.hpp>
+#include <libremidi/backends/android/observer.hpp>
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+struct backend
+{
+  using midi_in = android::midi_in;
+  using midi_out = android::midi_out;
+  using midi_observer = android::observer;
+  using midi_in_configuration = android::input_configuration;
+  using midi_out_configuration = android::output_configuration;
+  using midi_observer_configuration = android::observer_configuration;
+  static const constexpr auto API = libremidi::API::ANDROID_AMIDI;
+  static const constexpr std::string_view name = "android";
+  static const constexpr std::string_view display_name = "Android MIDI API";
+
+  static bool available() noexcept
+  {
+#if defined(__ANDROID__)
+    return true;
+#else
+    return false;
+#endif
+  }
+};
+}
+}

include/libremidi/backends/android/config.hpp

@@ -0,0 +1,23 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+struct input_configuration
+{
+  std::string_view client_name = "libremidi client";
+};
+
+struct output_configuration
+{
+  std::string_view client_name = "libremidi client";
+};
+
+struct observer_configuration
+{
+  std::string_view client_name = "libremidi client";
+};
+}
+}

include/libremidi/backends/android/helpers.cpp

@@ -0,0 +1,239 @@
+#include <libremidi/backends/android/helpers.hpp>
+#include <libremidi/backends/android/midi_in.hpp>
+#include <libremidi/backends/android/midi_out.hpp>
+
+NAMESPACE_LIBREMIDI::android
+{
+// Main source of knowledge is RtMidi implementation
+// which was done by Yellow Labrador
+
+JNIEnv* context::get_thread_env()
+{
+  JNIEnv* env;
+  JavaVM* jvm;
+  jsize count;
+  if (JNI_GetCreatedJavaVMs(&jvm, 1, &count) != JNI_OK || count < 1)
+  {
+    LOGE("No JVM found");
+    return nullptr;
+  }
+
+  if (jvm->GetEnv((void**)&env, JNI_VERSION_1_6) == JNI_EDETACHED)
+  {
+    if (jvm->AttachCurrentThread(&env, nullptr) != JNI_OK)
+    {
+      LOGE("Failed to attach thread");
+      return nullptr;
+    }
+  }
+
+  return env;
+}
+
+jobject context::get_context(JNIEnv* env)
+{
+  auto activity_thread = env->FindClass("android/app/ActivityThread");
+  auto current_activity_thread = env->GetStaticMethodID(
+      activity_thread, "currentActivityThread", "()Landroid/app/ActivityThread;");
+  auto at = env->CallStaticObjectMethod(activity_thread, current_activity_thread);
+
+  if (!at)
+  {
+    LOGE("Failed to get ActivityThread");
+    return nullptr;
+  }
+
+  auto get_application
+      = env->GetMethodID(activity_thread, "getApplication", "()Landroid/app/Application;");
+  auto app = env->CallObjectMethod(at, get_application);
+
+  if (!app)
+  {
+    LOGE("Failed to get Application");
+    return nullptr;
+  }
+
+  return app;
+}
+
+jobject context::get_midi_manager(JNIEnv* env, jobject ctx)
+{
+  auto context_class = env->FindClass("android/content/Context");
+  auto get_system_service = env->GetMethodID(
+      context_class, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;");
+  auto midi_service_str = env->NewStringUTF("midi");
+  auto service = env->CallObjectMethod(ctx, get_system_service, midi_service_str);
+  env->DeleteLocalRef(midi_service_str);
+  return service;
+}
+
+void context::refresh_midi_devices(JNIEnv* env, jobject ctx, bool is_output)
+{
+  cleanup_devices(env);
+
+  auto midi_service = get_midi_manager(env, ctx);
+  if (!midi_service)
+    return;
+
+  auto midi_mgr_class = env->FindClass("android/media/midi/MidiManager");
+  auto get_devices_method
+      = env->GetMethodID(midi_mgr_class, "getDevices", "()[Landroid/media/midi/MidiDeviceInfo;");
+  auto device_array = (jobjectArray)env->CallObjectMethod(midi_service, get_devices_method);
+
+  auto device_info_class = env->FindClass("android/media/midi/MidiDeviceInfo");
+  auto get_input_count = env->GetMethodID(device_info_class, "getInputPortCount", "()I");
+  auto get_output_count = env->GetMethodID(device_info_class, "getOutputPortCount", "()I");
+
+  jsize count = env->GetArrayLength(device_array);
+  for (jsize i = 0; i < count; ++i)
+  {
+    auto device_info = env->GetObjectArrayElement(device_array, i);
+    int port_count = is_output ? env->CallIntMethod(device_info, get_input_count)
+                               : env->CallIntMethod(device_info, get_output_count);
+
+    if (port_count > 0)
+    {
+      midi_devices.push_back(env->NewGlobalRef(device_info));
+    }
+    env->DeleteLocalRef(device_info);
+  }
+
+  env->DeleteLocalRef(device_array);
+  env->DeleteLocalRef(midi_service);
+}
+
+std::string context::port_name(JNIEnv* env, unsigned int port_number)
+{
+  if (port_number >= midi_devices.size())
+  {
+    LOGE("Invalid port number");
+    return "";
+  }
+
+  auto device_info_class = env->FindClass("android/media/midi/MidiDeviceInfo");
+  auto get_props_method
+      = env->GetMethodID(device_info_class, "getProperties", "()Landroid/os/Bundle;");
+  auto bundle = env->CallObjectMethod(midi_devices[port_number], get_props_method);
+
+  auto bundle_class = env->FindClass("android/os/Bundle");
+  auto get_string_method
+      = env->GetMethodID(bundle_class, "getString", "(Ljava/lang/String;)Ljava/lang/String;");
+  auto key = env->NewStringUTF("name");
+  auto name_str = (jstring)env->CallObjectMethod(bundle, get_string_method, key);
+
+  std::string result;
+  if (name_str)
+  {
+    const char* name_chars = env->GetStringUTFChars(name_str, nullptr);
+    result = name_chars;
+    env->ReleaseStringUTFChars(name_str, name_chars);
+    env->DeleteLocalRef(name_str);
+  }
+
+  env->DeleteLocalRef(key);
+  env->DeleteLocalRef(bundle);
+
+  return result;
+}
+
+void context::cleanup_devices(JNIEnv* env)
+{
+  for (jobject device : midi_devices)
+  {
+    env->DeleteGlobalRef(device);
+  }
+  midi_devices.clear();
+}
+
+void context::open_device(jobject device_info, void* target, bool is_output)
+{
+  auto env = get_thread_env();
+  if (!env)
+    return;
+
+  auto ctx = get_context(env);
+  if (!ctx)
+    return;
+
+  auto midi_mgr = get_midi_manager(env, ctx);
+  if (!midi_mgr)
+    return;
+
+  // Check if we're on the main thread
+  auto looper_class = env->FindClass("android/os/Looper");
+  auto get_my_looper_method
+      = env->GetStaticMethodID(looper_class, "myLooper", "()Landroid/os/Looper;");
+  auto my_looper = env->CallStaticObjectMethod(looper_class, get_my_looper_method);
+
+  jobject handler = nullptr;
+  if (!my_looper)
+  {
+    LOGI("Not on a Looper thread, using main looper");
+    auto get_main_looper_method
+        = env->GetStaticMethodID(looper_class, "getMainLooper", "()Landroid/os/Looper;");
+    auto main_looper = env->CallStaticObjectMethod(looper_class, get_main_looper_method);
+
+    auto handler_class = env->FindClass("android/os/Handler");
+    auto handler_ctor = env->GetMethodID(handler_class, "<init>", "(Landroid/os/Looper;)V");
+    handler = env->NewObject(handler_class, handler_ctor, main_looper);
+
+    env->DeleteLocalRef(main_looper);
+  }
+
+  // Create the callback listener
+  auto callback_class = env->FindClass("dev/celtera/libremidi/MidiDeviceCallback");
+  if (!callback_class)
+  {
+    LOGE("MidiDeviceCallback class not found - ensure the Java class is loaded");
+    if (handler)
+      env->DeleteLocalRef(handler);
+    return;
+  }
+
+  auto callback_ctor = env->GetMethodID(callback_class, "<init>", "(JZ)V");
+  auto callback
+      = env->NewObject(callback_class, callback_ctor, (jlong)target, (jboolean)is_output);
+
+  // Open the device
+  auto midi_mgr_class = env->FindClass("android/media/midi/MidiManager");
+  auto open_device_method = env->GetMethodID(
+      midi_mgr_class, "openDevice",
+      "(Landroid/media/midi/MidiDeviceInfo;Landroid/media/midi/"
+      "MidiManager$OnDeviceOpenedListener;Landroid/os/Handler;)V");
+
+  env->CallVoidMethod(midi_mgr, open_device_method, device_info, callback, handler);
+
+  env->DeleteLocalRef(callback);
+  if (handler)
+    env->DeleteLocalRef(handler);
+}
+
+extern "C" JNIEXPORT void JNICALL Java_dev_celtera_libremidi_MidiDeviceCallback_onDeviceOpened(
+    JNIEnv* env, jobject /*thiz*/, jobject midi_device, jlong target_ptr, jboolean is_output)
+{
+  if (!midi_device || target_ptr == 0)
+  {
+    LOGE("Invalid device or target pointer in callback");
+    return;
+  }
+
+  AMidiDevice* amidi_device = nullptr;
+  AMidiDevice_fromJava(env, midi_device, &amidi_device);
+
+  if (!amidi_device)
+  {
+    LOGE("Failed to convert Java MIDI device to AMidiDevice");
+    return;
+  }
+
+  if (is_output)
+  {
+    midi_out::open_callback(reinterpret_cast<midi_out*>(target_ptr), amidi_device);
+  }
+  else
+  {
+    midi_in::open_callback(reinterpret_cast<midi_in*>(target_ptr), amidi_device);
+  }
+}
+
+}

include/libremidi/backends/android/helpers.hpp

@@ -0,0 +1,40 @@
+#pragma once
+#include <libremidi/error.hpp>
+
+#include <amidi/AMidi.h>
+#include <android/log.h>
+
+#include <jni.h>
+#include <pthread.h>
+
+#include <string>
+#include <vector>
+
+#define LOG_TAG "libremidi"
+#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
+#define LOGW(...) __android_log_print(ANDROID_LOG_WARN, LOG_TAG, __VA_ARGS__)
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
+#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+struct context
+{
+  static inline std::string client_name;
+  static inline std::vector<jobject> midi_devices;
+
+  static JNIEnv* get_thread_env();
+  static jobject get_context(JNIEnv* env);
+  static jobject get_midi_manager(JNIEnv* env, jobject context);
+  static void refresh_midi_devices(JNIEnv* env, jobject context, bool is_output);
+  static void open_device(jobject device_info, void* target, bool is_output);
+  static std::string port_name(JNIEnv* env, unsigned int port_number);
+  static void cleanup_devices(JNIEnv* env);
+};
+
+extern "C" JNIEXPORT void JNICALL Java_dev_celtera_libremidi_MidiDeviceCallback_onDeviceOpened(
+    JNIEnv* env, jobject /*thiz*/, jobject midi_device, jlong target_ptr, jboolean is_output);
+}
+}

include/libremidi/backends/android/midi_in.hpp

@@ -0,0 +1,165 @@
+#pragma once
+#include <libremidi/backends/android/config.hpp>
+#include <libremidi/backends/android/helpers.hpp>
+#include <libremidi/detail/midi_in.hpp>
+#include <libremidi/detail/midi_stream_decoder.hpp>
+
+#include <atomic>
+#include <chrono>
+#include <thread>
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+class midi_in
+    : public midi1::in_api
+    , public error_handler
+{
+public:
+  explicit midi_in(
+      libremidi::input_configuration&& conf, libremidi::android::input_configuration aconf)
+      : configuration{std::move(conf)}
+  {
+    if (!context::client_name.empty() && context::client_name != aconf.client_name)
+    {
+      libremidi_handle_error(
+          configuration, "Android backend only supports one client name per process");
+      return;
+    }
+    context::client_name = std::string(aconf.client_name);
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_in() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override
+  {
+    return libremidi::API::ANDROID_AMIDI;
+  }
+
+  stdx::error open_port(const input_port& port, std::string_view /*name*/) override
+  {
+    if (is_port_open())
+    {
+      libremidi_handle_error(configuration, "midi_in::open_port: a port is already open");
+      return std::errc{};
+    }
+
+    const unsigned int port_number = port.port;
+    auto env = context::get_thread_env();
+    if (!env)
+    {
+      libremidi_handle_error(configuration, "midi_in::open_port: failed to get JNI environment");
+      return std::errc{};
+    }
+
+    auto ctx = context::get_context(env);
+    if (!ctx)
+    {
+      libremidi_handle_error(configuration, "midi_in::open_port: failed to get Android context");
+      return std::errc{};
+    }
+
+    context::refresh_midi_devices(env, ctx, false);
+
+    if (port_number >= context::midi_devices.size())
+    {
+      libremidi_handle_error(configuration, "midi_in::open_port: invalid port number");
+      return std::errc{};
+    }
+
+    port_open = true;
+    running = true;
+    context::open_device(context::midi_devices[port_number], this, false);
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override
+  {
+    if (!is_port_open())
+      return std::errc{};
+
+    running = false;
+
+    if (poll_thread.joinable())
+    {
+      poll_thread.join();
+    }
+
+    if (midi_output_port)
+    {
+      AMidiOutputPort_close(midi_output_port);
+      midi_output_port = nullptr;
+    }
+
+    if (receive_device)
+    {
+      AMidiDevice_release(receive_device);
+      receive_device = nullptr;
+    }
+
+    port_open = false;
+    return stdx::error{};
+  }
+
+  bool is_port_open() const noexcept { return port_open; }
+
+  void start_midi_thread() { poll_thread = std::thread(&midi_in::poll_midi, this); }
+
+  timestamp absolute_timestamp() const noexcept override { return system_ns(); }
+  void poll_midi()
+  {
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = false,
+        .absolute_is_monotonic = false,
+        .has_samples = false,
+    };
+
+    uint8_t buffer[1024];
+    int32_t op_code;
+    int64_t timestamp;
+    size_t num_bytes;
+
+    while (running)
+    {
+      std::this_thread::sleep_for(std::chrono::milliseconds(1));
+
+      ssize_t num_messages = AMidiOutputPort_receive(
+          midi_output_port, &op_code, buffer, sizeof(buffer), &num_bytes, &timestamp);
+
+      if (num_messages < 0)
+      {
+        LOGE("Error receiving MIDI data: %d", (int)num_messages);
+        continue;
+      }
+
+      if (num_messages > 0 && num_bytes > 0)
+      {
+        const auto to_ns = [=] { return timestamp; };
+
+        m_processing.on_bytes_multi(
+            {buffer, buffer + num_bytes},
+            m_processing.timestamp<timestamp_info>(to_ns, timestamp));
+      }
+    }
+  }
+
+  static void open_callback(midi_in* self, AMidiDevice* device)
+  {
+    self->receive_device = device;
+    AMidiOutputPort_open(device, 0, &self->midi_output_port);
+    self->start_midi_thread();
+  }
+
+private:
+  libremidi::input_configuration configuration;
+  AMidiDevice* receive_device = nullptr;
+  AMidiOutputPort* midi_output_port = nullptr;
+  std::thread poll_thread;
+  std::atomic<bool> port_open{false};
+  std::atomic<bool> running{false};
+  midi1::input_state_machine m_processing{this->configuration};
+};
+}
+}

include/libremidi/backends/android/midi_out.hpp

@@ -0,0 +1,126 @@
+#pragma once
+#include <libremidi/backends/android/config.hpp>
+#include <libremidi/backends/android/helpers.hpp>
+#include <libremidi/detail/midi_out.hpp>
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+class midi_out final
+    : public midi1::out_api
+    , public error_handler
+{
+public:
+  explicit midi_out(
+      libremidi::output_configuration&& conf, libremidi::android::output_configuration aconf)
+      : configuration{std::move(conf)}
+  {
+    if (!context::client_name.empty() && context::client_name != aconf.client_name)
+    {
+      libremidi_handle_error(
+          configuration, "Android backend only supports one client name per process");
+      return;
+    }
+    context::client_name = std::string(aconf.client_name);
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_out() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override
+  {
+    return libremidi::API::ANDROID_AMIDI;
+  }
+
+  stdx::error open_port(const output_port& port, std::string_view /*name*/) override
+  {
+    if (is_port_open())
+    {
+      libremidi_handle_error(configuration, "midi_out::open_port: a port is already open");
+      return std::errc{};
+    }
+
+    const unsigned int port_number = port.port;
+
+    auto env = context::get_thread_env();
+    if (!env)
+    {
+      libremidi_handle_error(configuration, "midi_out::open_port: failed to get JNI environment");
+      return std::errc{};
+    }
+
+    auto ctx = context::get_context(env);
+    if (!ctx)
+    {
+      libremidi_handle_error(configuration, "midi_out::open_port: failed to get Android context");
+      return std::errc{};
+    }
+
+    context::refresh_midi_devices(env, ctx, true);
+
+    if (port_number >= context::midi_devices.size())
+    {
+      libremidi_handle_error(configuration, "midi_out::open_port: invalid port number");
+      return std::errc{};
+    }
+
+    port_open = true;
+    context::open_device(context::midi_devices[port_number], this, true);
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override
+  {
+    if (!is_port_open())
+      return std::errc{};
+
+    if (midi_input_port)
+    {
+      AMidiInputPort_close(midi_input_port);
+      midi_input_port = nullptr;
+    }
+
+    if (send_device)
+    {
+      AMidiDevice_release(send_device);
+      send_device = nullptr;
+    }
+
+    port_open = false;
+    return stdx::error{};
+  }
+
+  bool is_port_open() const noexcept { return port_open; }
+
+  stdx::error send_message(const unsigned char* message, size_t size) override
+  {
+    if (!is_port_open() || !midi_input_port)
+    {
+      libremidi_handle_error(configuration, "midi_out::send_message: port is not open");
+      return std::errc{};
+    }
+
+    ssize_t result = AMidiInputPort_send(midi_input_port, message, size);
+    if (result < 0)
+    {
+      libremidi_handle_error(configuration, "midi_out::send_message: failed to send MIDI data");
+      return std::errc{};
+    }
+    return stdx::error{};
+  }
+
+  static void open_callback(midi_out* self, AMidiDevice* device)
+  {
+    self->send_device = device;
+    AMidiInputPort_open(device, 0, &self->midi_input_port);
+  }
+
+private:
+  libremidi::output_configuration configuration;
+  AMidiDevice* send_device = nullptr;
+  AMidiInputPort* midi_input_port = nullptr;
+  bool port_open = false;
+};
+}
+}

include/libremidi/backends/android/observer.hpp

@@ -0,0 +1,93 @@
+#pragma once
+#include <libremidi/backends/android/config.hpp>
+#include <libremidi/backends/android/helpers.hpp>
+#include <libremidi/detail/observer.hpp>
+
+NAMESPACE_LIBREMIDI
+{
+namespace android
+{
+class observer final
+    : public libremidi::observer_api
+    , public error_handler
+{
+public:
+  explicit observer(
+      libremidi::observer_configuration&& conf, libremidi::android::observer_configuration aconf)
+      : configuration{std::move(conf)}
+  {
+    if (!context::client_name.empty() && context::client_name != aconf.client_name)
+    {
+      LOGW("Android backend only supports one client name per process");
+    }
+    context::client_name = std::string(aconf.client_name);
+  }
+
+  ~observer()
+  {
+    auto env = context::get_thread_env();
+    if (env)
+    {
+      context::cleanup_devices(env);
+    }
+  }
+
+  libremidi::API get_current_api() const noexcept override
+  {
+    return libremidi::API::ANDROID_AMIDI;
+  }
+
+  std::vector<libremidi::input_port> get_input_ports() const noexcept override
+  {
+    auto env = context::get_thread_env();
+    if (!env)
+      return {};
+
+    auto ctx = context::get_context(env);
+    if (!ctx)
+      return {};
+
+    context::refresh_midi_devices(env, ctx, false);
+
+    std::vector<libremidi::input_port> ports;
+    for (size_t i = 0; i < context::midi_devices.size(); ++i)
+    {
+      libremidi::input_port port;
+      port.api = libremidi::API::ANDROID_AMIDI;
+      port.port_name = context::port_name(env, i);
+      port.port = i;
+      ports.push_back(std::move(port));
+    }
+
+    return ports;
+  }
+
+  std::vector<libremidi::output_port> get_output_ports() const noexcept override
+  {
+    auto env = context::get_thread_env();
+    if (!env)
+      return {};
+
+    auto ctx = context::get_context(env);
+    if (!ctx)
+      return {};
+
+    context::refresh_midi_devices(env, ctx, true);
+
+    std::vector<libremidi::output_port> ports;
+    for (size_t i = 0; i < context::midi_devices.size(); ++i)
+    {
+      libremidi::output_port port;
+      port.port_name = context::port_name(env, i);
+      port.port = i;
+      ports.push_back(std::move(port));
+    }
+
+    return ports;
+  }
+
+private:
+  libremidi::observer_configuration configuration;
+};
+}
+}

include/libremidi/backends/coremidi.hpp

@@ -3,7 +3,9 @@
 #include <libremidi/backends/coremidi/midi_out.hpp>
 #include <libremidi/backends/coremidi/observer.hpp>
 
-namespace libremidi
+#include <string_view>
+
+NAMESPACE_LIBREMIDI
 {
 struct core_backend
 {
@@ -14,8 +16,8 @@ struct core_backend
   using midi_out_configuration = coremidi_output_configuration;
   using midi_observer_configuration = coremidi_observer_configuration;
   static const constexpr auto API = libremidi::API::COREMIDI;
-  static const constexpr auto name = "core";
+  static const constexpr std::string_view name = "core";
-  static const constexpr auto display_name = "CoreMIDI";
+  static const constexpr std::string_view display_name = "CoreMIDI";
 
   static constexpr inline bool available() noexcept { return true; }
 };

include/libremidi/backends/coremidi/config.hpp

@@ -16,8 +16,9 @@ typedef UInt32 MIDIObjectRef;
 typedef MIDIObjectRef MIDIClientRef;
 #else
 using MIDIClientRef = uint32_t;
+using MIDIObjectRef = uint32_t;
 #endif
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 struct coremidi_input_configuration

include/libremidi/backends/coremidi/error_domain.hpp

@@ -0,0 +1,72 @@
+#pragma once
+#include <libremidi/error.hpp>
+
+#include <CoreMIDI/CoreMIDI.h>
+
+NAMESPACE_LIBREMIDI
+{
+struct coremidi_error_domain : public stdx::error_domain
+{
+public:
+  constexpr coremidi_error_domain() noexcept
+      : error_domain{{0xa32b080ac770514eULL, 0xef59a407f921da43ULL}}
+  {
+  }
+
+  stdx::string_ref name() const noexcept override { return "coremidi"; }
+
+  bool equivalent(const stdx::error& lhs, const stdx::error& rhs) const noexcept override
+  {
+    if (lhs.domain() == rhs.domain())
+      return error_cast<std::errc>(lhs) == error_cast<std::errc>(rhs);
+
+    return false;
+  }
+
+  stdx::string_ref message(const stdx::error& e) const noexcept override
+  {
+    switch (error_cast<OSStatus>(e))
+    {
+      case kMIDIInvalidClient:
+        return "Invalid Client";
+      case kMIDIInvalidPort:
+        return "Invalid Port";
+      case kMIDIWrongEndpointType:
+        return "Wrong EndpointT ype";
+      case kMIDINoConnection:
+        return "No Connection";
+      case kMIDIUnknownEndpoint:
+        return "Unknown Endpoint";
+      case kMIDIUnknownProperty:
+        return "Unknown Property";
+      case kMIDIWrongPropertyType:
+        return "Wrong Property Type";
+      case kMIDINoCurrentSetup:
+        return "No Current Setup";
+      case kMIDIMessageSendErr:
+        return "Message Send Error";
+      case kMIDIServerStartErr:
+        return "Server Start Error";
+      case kMIDISetupFormatErr:
+        return "Setup Format Error";
+      case kMIDIWrongThread:
+        return "Wrong Thread";
+      case kMIDIObjectNotFound:
+        return "Object Not Found";
+      case kMIDIIDNotUnique:
+        return "ID Not Unique";
+      case kMIDINotPermitted:
+        return "Not Permitted";
+      case kMIDIUnknownError:
+        return "Unknown Error";
+    }
+    return "Unknown error code";
+  }
+};
+
+inline stdx::error from_osstatus(OSStatus ret) noexcept
+{
+  static constexpr coremidi_error_domain domain{};
+  return {ret, domain};
+}
+}

include/libremidi/backends/coremidi/helpers.hpp

@@ -1,6 +1,8 @@
 #pragma once
+#include <libremidi/backends/coremidi/error_domain.hpp>
 #include <libremidi/detail/memory.hpp>
 #include <libremidi/detail/midi_api.hpp>
+#include <libremidi/error_handler.hpp>
 #include <libremidi/input_configuration.hpp>
 
 #include <CoreMIDI/CoreMIDI.h>
@@ -19,16 +21,16 @@
   #define LIBREMIDI_AUDIO_GET_CURRENT_HOST_TIME AudioGetCurrentHostTime
 #endif
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 using CFString_handle = unique_handle<const __CFString, CFRelease>;
 using CFStringMutable_handle = unique_handle<__CFString, CFRelease>;
-namespace
+
-{
+LIBREMIDI_STATIC std::string get_string_property(MIDIObjectRef object, CFStringRef property) noexcept
-static inline std::string get_string_property(MIDIObjectRef object, CFStringRef property) noexcept
 {
   CFStringRef res;
-  MIDIObjectGetStringProperty(object, property, &res);
+  if (MIDIObjectGetStringProperty(object, property, &res) || !res)
+    return {};
 
   char name[256];
   CFStringGetCString(res, name, sizeof(name), kCFStringEncodingUTF8);
@@ -36,14 +38,14 @@ static inline std::string get_string_property(MIDIObjectRef object, CFStringRef
   return name;
 }
 
-static inline int32_t get_int_property(MIDIObjectRef object, CFStringRef property) noexcept
+LIBREMIDI_STATIC int32_t get_int_property(MIDIObjectRef object, CFStringRef property) noexcept
 {
   SInt32 res;
   MIDIObjectGetIntegerProperty(object, property, &res);
   return res;
 }
 
-static inline CFString_handle toCFString(std::string_view str) noexcept
+LIBREMIDI_STATIC CFString_handle toCFString(std::string_view str) noexcept
 {
   return CFString_handle{CFStringCreateWithCString(nullptr, str.data(), kCFStringEncodingASCII)};
 }
@@ -68,20 +70,22 @@ inline uint64_t AudioConvertHostTimeToNanos(uint64_t hostTime)
   return static_cast<uint64_t>(res);
 }
 #endif
+
+LIBREMIDI_STATIC auto get_cfstring_property(MIDIObjectRef prop, CFStringRef name)
+{
+  CFStringRef str = nullptr;
+  MIDIObjectGetStringProperty(prop, name, &str);
+  return CFString_handle{str};
+}
+
 // This function was submitted by Douglas Casey Tucker and apparently
 // derived largely from PortMidi.
 inline CFStringRef EndpointName(MIDIEndpointRef endpoint, bool isExternal)
 {
   CFMutableStringRef result = CFStringCreateMutable(nullptr, 0);
 
-  static constexpr auto getProp = [](MIDIObjectRef prop) {
-    CFStringRef str = nullptr;
-    MIDIObjectGetStringProperty(prop, kMIDIPropertyName, &str);
-    return CFString_handle{str};
-  };
-
   // Begin with the endpoint's name.
-  if (auto endpoint_name = getProp(endpoint))
+  if (auto endpoint_name = get_cfstring_property(endpoint, kMIDIPropertyName))
   {
     CFStringAppend(result, endpoint_name.get());
   }
@@ -98,7 +102,7 @@ inline CFStringRef EndpointName(MIDIEndpointRef endpoint, bool isExternal)
   if (CFStringGetLength(result) == 0)
   {
     // endpoint name has zero length -- try the entity
-    if (auto entity_name = getProp(entity))
+    if (auto entity_name = get_cfstring_property(entity, kMIDIPropertyName))
     {
       CFStringAppend(result, entity_name.get());
     }
@@ -109,7 +113,7 @@ inline CFStringRef EndpointName(MIDIEndpointRef endpoint, bool isExternal)
   if (device == 0)
     goto finish;
 
-  if (auto dev_name = getProp(device))
+  if (auto dev_name = get_cfstring_property(device, kMIDIPropertyName))
   {
     const auto dev_strlen = CFStringGetLength(dev_name.get());
 
@@ -215,22 +219,19 @@ locate_object(auto& self, const port_information& info, MIDIObjectType requested
   auto ret = MIDIObjectFindByUniqueID(uid, &object, &type);
   if (ret != noErr)
   {
-    self.template error<invalid_parameter_error>(
+    self.libremidi_handle_error(self.configuration, "cannot find port: " + info.port_name);
-        self.configuration, "coremidi::locate_object: cannot find port: " + info.port_name);
     return 0;
   }
 
   if (type != requested_type || object == 0)
   {
-    self.template error<invalid_parameter_error>(
+    self.libremidi_handle_error(
-        self.configuration, "coremidi::locate_object: invalid object: " + info.port_name + " : "
+        self.configuration, "invalid object: " + info.port_name + " : " + std::to_string(object));
-                                + std::to_string(object));
     return 0;
   }
 
   return object;
 }
-}
 
 // A structure to hold variables related to the CoreMIDI API
 // implementation.
@@ -255,6 +256,13 @@ struct coremidi_data
     }
   }
 
+  void close_client(auto& self)
+  {
+    self.client_open_ = std::errc::not_connected;
+    if (!self.configuration.context)
+      MIDIClientDispose(self.client);
+  }
+
   static uint64_t time_in_nanos(MIDITimeStamp tp) noexcept
   {
     if (tp == 0)
@@ -319,6 +327,23 @@ struct coremidi_data
       }
     }
   }
+
+  stdx::error close_port()
+  {
+    if (this->endpoint)
+    {
+      MIDIEndpointDispose(this->endpoint);
+      this->endpoint = 0;
+    }
+
+    if (this->port)
+    {
+      MIDIPortDispose(this->port);
+      this->port = 0;
+    }
+
+    return stdx::error{};
+  }
 };
 
 }

include/libremidi/backends/coremidi/midi_in.hpp

@@ -4,14 +4,15 @@
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/midi_stream_decoder.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class midi_in_core final
     : public midi1::in_api
-    , private coremidi_data
+    , public coremidi_data
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : input_configuration
       , coremidi_input_configuration
@@ -23,11 +24,13 @@ public:
   {
     if (auto result = init_client(configuration); result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "midi_in_core: error creating MIDI client object: " + std::to_string(result));
+      client_open_ = from_osstatus(result);
       return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_in_core() override
@@ -38,33 +41,18 @@ public:
     if (this->endpoint)
       MIDIEndpointDispose(this->endpoint);
 
-    close_client();
+    close_client(*this);
-  }
-
-  void close_client()
-  {
-    if (!configuration.context)
-      MIDIClientDispose(this->client);
-  }
-
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_core: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_core: set_port_name unsupported");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI; }
 
-  bool open_port(const input_port& info, std::string_view portName) override
+  stdx::error open_port(const input_port& info, std::string_view portName) override
   {
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, false);
 
     auto source = locate_object(*this, info, kMIDIObjectType_Source);
     if (source == 0)
-      return false;
+      return std::errc::invalid_argument;
 
     // Create our local sink
     MIDIPortRef port;
@@ -73,29 +61,27 @@ public:
 
     if (result != noErr)
     {
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration, "midi_in_core::open_port: error creating macOS MIDI input port: "
+          this->configuration, "error creating macOS MIDI input port: " + std::to_string(result));
-                                   + std::to_string(result));
+      return from_osstatus(result);
-      return false;
     }
 
     // Make the connection.
     if (result = MIDIPortConnectSource(port, source, nullptr); result != noErr)
     {
       MIDIPortDispose(port);
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error connecting macOS MIDI input port.");
-          this->configuration, "midi_in_core::open_port: error connecting macOS MIDI input port.");
+      return from_osstatus(result);
-      return false;
     }
 
     // Save our api-specific port information.
     this->port = port;
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
     // Create a virtual MIDI input destination.
     MIDIEndpointRef endpoint;
@@ -104,32 +90,19 @@ public:
 
     if (result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_in_core::open_virtual_port: error creating virtual macOS MIDI "
+          "error creating virtual macOS MIDI "
           "destination.");
-      return false;
+      return from_osstatus(result);
     }
 
     // Save our api-specific connection information.
     this->endpoint = endpoint;
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    if (this->endpoint)
-    {
-      MIDIEndpointDispose(this->endpoint);
-      this->endpoint = 0;
-    }
-
-    if (this->port)
-    {
-      MIDIPortDispose(this->port);
-      this->port = 0;
-    }
-  }
 
   timestamp absolute_timestamp() const noexcept override
   {
@@ -158,16 +131,13 @@ public:
       // MIDIPacketLists, they must be handled by multiple calls to this
       // function.
 
-      if (packet->length == 0)
+      if (packet->length > 0)
       {
-        packet = MIDIPacketNext(packet);
-        continue;
-      }
-
         auto to_ns = [packet] { return time_in_nanos(packet->timeStamp); };
         self.m_processing.on_bytes_multi(
             {packet->data, packet->data + packet->length},
             self.m_processing.timestamp<timestamp_info>(to_ns, 0));
+      }
 
       packet = MIDIPacketNext(packet);
     }

include/libremidi/backends/coremidi/midi_out.hpp

@@ -3,14 +3,15 @@
 #include <libremidi/backends/coremidi/helpers.hpp>
 #include <libremidi/detail/midi_out.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class midi_out_core final
     : public midi1::out_api
-    , private coremidi_data
+    , public coremidi_data
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : output_configuration
       , coremidi_output_configuration
@@ -22,11 +23,13 @@ public:
   {
     if (auto result = init_client(configuration); result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "midi_out_core: error creating MIDI client object: " + std::to_string(result));
+      client_open_ = from_osstatus(result);
       return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_core()
@@ -36,119 +39,80 @@ public:
     if (this->endpoint)
       MIDIEndpointDispose(this->endpoint);
 
-    close_client();
+    close_client(*this);
-  }
-
-  void close_client()
-  {
-    if (!configuration.context)
-      MIDIClientDispose(this->client);
-  }
-
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_core: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_core: set_port_name unsupported");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI; }
 
-  bool open_port(const output_port& info, std::string_view portName) override
+  stdx::error open_port(const output_port& info, std::string_view portName) override
   {
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, false);
 
     // Find where we want to send
     auto destination = locate_object(*this, info, kMIDIObjectType_Destination);
     if (destination == 0)
-      return false;
+      return std::errc::invalid_argument;
 
     // Create our local source
     MIDIPortRef port;
     OSStatus result = MIDIOutputPortCreate(this->client, toCFString(portName).get(), &port);
     if (result != noErr)
     {
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating macOS MIDI output port.");
-          this->configuration, "midi_out_core::open_port: error creating macOS MIDI output port.");
+      return from_osstatus(result);
-      return false;
     }
 
     // Save our api-specific connection information.
     this->port = port;
     this->destinationId = destination;
 
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
-    if (this->endpoint)
-    {
-      warning(
-          configuration,
-          "midi_out_core::open_virtual_port: a virtual output port already "
-          "exists!");
-      return false;
-    }
-
     // Create a virtual MIDI output source.
     MIDIEndpointRef endpoint;
     OSStatus result = MIDISourceCreate(this->client, toCFString(portName).get(), &endpoint);
 
     if (result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating macOS virtual MIDI source.");
-          this->configuration,
+
-          "midi_out_core::initialize: error creating macOS virtual MIDI source.");
+      return from_osstatus(result);
-      return false;
     }
 
     // Save our api-specific connection information.
     this->endpoint = endpoint;
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    if (this->endpoint)
-    {
-      MIDIEndpointDispose(this->endpoint);
-      this->endpoint = 0;
-    }
 
-    if (this->port)
+  stdx::error send_message(const unsigned char* message, size_t size) override
-    {
-      MIDIPortDispose(this->port);
-      this->port = 0;
-    }
-  }
-
-  void send_message(const unsigned char* message, size_t size) override
   {
     unsigned int nBytes = static_cast<unsigned int>(size);
     if (nBytes == 0)
     {
-      warning(configuration, "midi_out_core::send_message: no data in message argument!");
+      libremidi_handle_warning(configuration, "no data in message argument!");
-      return;
+      return std::errc::invalid_argument;
     }
 
     if (message[0] != 0xF0 && nBytes > 3)
     {
-      warning(
+      libremidi_handle_warning(
           configuration,
-          "midi_out_core::send_message: message format problem ... not sysex but "
+          "message format problem ... not sysex but "
           "> 3 bytes?");
-      return;
+      return std::errc::bad_message;
     }
 
     const MIDITimeStamp timestamp = LIBREMIDI_AUDIO_GET_CURRENT_HOST_TIME();
 
     const ByteCount bufsize = nBytes > 65535 ? 65535 : nBytes;
-    Byte buffer[bufsize + 16]; // pad for other struct members
+    Byte* buffer = (Byte*)alloca(bufsize + 16); // pad for other struct members
-    ByteCount listSize = sizeof(buffer);
+    ByteCount listSize = bufsize + 16;
     MIDIPacketList* packetList = (MIDIPacketList*)buffer;
 
     ByteCount remainingBytes = nBytes;
@@ -166,9 +130,9 @@ public:
 
       if (!packet)
       {
-        error<driver_error>(
+        libremidi_handle_error(this->configuration, "could not allocate packet list");
-            this->configuration, "midi_out_core::send_message: could not allocate packet list");
+
-        return;
+        return std::errc::message_size;
       }
 
       // Send to any destinations that may have connected to us.
@@ -177,10 +141,11 @@ public:
         auto result = MIDIReceived(this->endpoint, packetList);
         if (result != noErr)
         {
-          warning(
+          libremidi_handle_warning(
               this->configuration,
-              "midi_out_core::send_message: error sending MIDI to virtual "
+              "error sending MIDI to virtual "
               "destinations.");
+          return std::errc::io_error;
         }
       }
 
@@ -190,12 +155,12 @@ public:
         auto result = MIDISend(this->port, this->destinationId, packetList);
         if (result != noErr)
         {
-          warning(
+          libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-              this->configuration,
+          return std::errc::io_error;
-              "midi_out_core::send_message: error sending MIDI message to port.");
         }
       }
     }
+    return stdx::error{};
   }
 
   MIDIEndpointRef destinationId{};

include/libremidi/backends/coremidi/observer.hpp

@@ -7,7 +7,7 @@
 
 #include <bit>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class observer_core
     : public observer_api
@@ -22,6 +22,10 @@ public:
 
   explicit observer_core(observer_configuration&& conf, coremidi_observer_configuration&& apiconf)
       : configuration{std::move(conf), std::move(apiconf)}
+  {
+  }
+
+  void finish_init()
   {
     if (configuration.client_name.empty())
       configuration.client_name = "libremidi observer";
@@ -33,14 +37,12 @@ public:
         toCFString(configuration.client_name).get(),
         +[](const MIDINotification* message, void* ctx) {
       ((observer_core*)ctx)->notify(message);
-        },
+    }, this, &client);
-        this, &client);
 
     if (result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "midi_in_core: error creating MIDI client object: " + std::to_string(result));
       return;
     }
 
@@ -69,22 +71,65 @@ public:
     MIDIEndpointGetEntity(obj, &e);
     bool physical = bool(e);
 
-    bool ok = false;
+    bool ok = this->configuration.track_any;
     if (physical && this->configuration.track_hardware)
-      ok = true;
+      ok |= true;
     else if ((!physical) && this->configuration.track_virtual)
-      ok = true;
+      ok |= true;
 
     if (!ok)
       return {};
 
+    // Get the MIDI device from the entity
+    libremidi::transport_type type{};
+    libremidi::container_identifier usb_location_id{};
+    libremidi::device_identifier usb_vendor_product{};
+    {
+      MIDIDeviceRef device{};
+      if (MIDIEntityGetDevice(e, &device) == noErr)
+      {
+        if (device)
+        {
+          using enum libremidi::transport_type;
+          SInt32 devid_res{};
+          if (MIDIObjectGetIntegerProperty(device, CFSTR("USBLocationID"), &devid_res) == noErr)
+          {
+            type = (libremidi::transport_type)(hardware | usb);
+            usb_location_id = (uint64_t)devid_res;
+          }
+
+          SInt32 vendor_res{};
+          if (MIDIObjectGetIntegerProperty(device, CFSTR("USBVendorProduct"), &vendor_res)
+              == noErr)
+          {
+            type = (libremidi::transport_type)(hardware | usb);
+            usb_vendor_product = (uint64_t)vendor_res;
+          }
+
+          const auto driver = get_string_property(device, kMIDIPropertyDriverOwner);
+          if (driver == "com.apple.AppleMIDIUSBDriver")
+            type = (libremidi::transport_type)(hardware | usb);
+          if (driver == "com.apple.AppleMIDIBluetoothDriver")
+            type = (libremidi::transport_type)(hardware | bluetooth);
+          if (driver == "com.apple.AppleMIDIIACDriver")
+            type = (libremidi::transport_type)(software);
+          if (driver == "com.apple.AppleMIDIRTPDriver")
+            type = (libremidi::transport_type)(network);
+        }
+      }
+    }
+
     return std::conditional_t<Input, input_port, output_port>{
-        {.client = (std::uintptr_t)this->client,
+        {.api = get_current_api(),
+         .client = (std::uintptr_t)this->client,
+         .container = usb_location_id,
+         .device = usb_vendor_product,
          .port = std::bit_cast<uint32_t>(get_int_property(obj, kMIDIPropertyUniqueID)),
          .manufacturer = get_string_property(obj, kMIDIPropertyManufacturer),
          .device_name = get_string_property(obj, kMIDIPropertyModel),
          .port_name = get_string_property(obj, kMIDIPropertyName),
-         .display_name = get_string_property(obj, kMIDIPropertyDisplayName)}};
+         .display_name = get_string_property(obj, kMIDIPropertyDisplayName),
+         .type = type}};
   }
 
   std::vector<libremidi::input_port> get_input_ports() const noexcept override
@@ -173,3 +218,17 @@ private:
   MIDIClientRef client{};
 };
 }
+
+NAMESPACE_LIBREMIDI::coremidi
+{
+struct observer_impl : observer_core
+{
+  observer_impl(observer_configuration&& conf, coremidi_observer_configuration&& apiconf)
+      : observer_core{std::move(conf), std::move(apiconf)}
+  {
+    finish_init();
+  }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI; }
+};
+}

include/libremidi/backends/coremidi_ump.hpp

@@ -3,19 +3,21 @@
 #include <libremidi/backends/coremidi_ump/midi_out.hpp>
 #include <libremidi/backends/coremidi_ump/observer.hpp>
 
-namespace libremidi::coremidi_ump
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
 struct backend
 {
   using midi_in = midi_in_impl;
   using midi_out = midi_out_impl;
   using midi_observer = observer_impl;
-  using midi_in_configuration = coremidi_input_configuration;
+  using midi_in_configuration = coremidi_ump::input_configuration;
-  using midi_out_configuration = coremidi_output_configuration;
+  using midi_out_configuration = coremidi_ump::output_configuration;
-  using midi_observer_configuration = coremidi_observer_configuration;
+  using midi_observer_configuration = coremidi_ump::observer_configuration;
   static const constexpr auto API = libremidi::API::COREMIDI_UMP;
-  static const constexpr auto name = "core_ump";
+  static const constexpr std::string_view name = "core_ump";
-  static const constexpr auto display_name = "CoreMIDI UMP";
+  static const constexpr std::string_view display_name = "CoreMIDI UMP";
 
   static constexpr inline bool available() noexcept { return true; /* todo? */ }
 };

include/libremidi/backends/coremidi_ump/config.hpp

@@ -1,9 +1,23 @@
 #pragma once
 #include <libremidi/backends/coremidi/config.hpp>
 
-namespace libremidi::coremidi_ump
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
-using input_configuration = coremidi_input_configuration;
+struct input_configuration
-using output_configuration = coremidi_output_configuration;
+{
-using observer_configuration = coremidi_observer_configuration;
+  std::string client_name = "libremidi client";
+  std::optional<MIDIClientRef> context{};
+};
+
+struct output_configuration
+{
+  std::string client_name = "libremidi client";
+  std::optional<MIDIClientRef> context{};
+};
+
+struct observer_configuration
+{
+  std::string client_name = "libremidi client";
+  std::function<void(MIDIClientRef)> on_create_context{};
+};
 }

include/libremidi/backends/coremidi_ump/midi_in.hpp

@@ -2,32 +2,36 @@
 #include <libremidi/backends/coremidi_ump/config.hpp>
 #include <libremidi/backends/coremidi_ump/helpers.hpp>
 #include <libremidi/detail/midi_in.hpp>
+#include <libremidi/detail/midi_stream_decoder.hpp>
 
-namespace libremidi::coremidi_ump
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
 
 class midi_in_impl final
     : public midi2::in_api
-    , private coremidi_data
+    , public coremidi_data
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : ump_input_configuration
       , coremidi_ump::input_configuration
   {
   } configuration;
 
-  midi_in_impl(ump_input_configuration&& conf, coremidi_input_configuration&& apiconf)
+  midi_in_impl(ump_input_configuration&& conf, coremidi_ump::input_configuration&& apiconf)
       : configuration{std::move(conf), std::move(apiconf)}
   {
     if (auto result = init_client(configuration); result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "midi_in_core: error creating MIDI client object: " + std::to_string(result));
+      client_open_ = from_osstatus(result);
       return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_in_impl() override
@@ -38,33 +42,18 @@ public:
     if (this->endpoint)
       MIDIEndpointDispose(this->endpoint);
 
-    close_client();
+    close_client(*this);
-  }
-
-  void close_client()
-  {
-    if (!configuration.context)
-      MIDIClientDispose(this->client);
-  }
-
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_core: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_core: set_port_name unsupported");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI_UMP; }
 
-  bool open_port(const input_port& info, std::string_view portName) override
+  stdx::error open_port(const input_port& info, std::string_view portName) override
   {
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, false);
 
     auto source = locate_object(*this, info, kMIDIObjectType_Source);
     if (source == 0)
-      return false;
+      return std::errc::invalid_argument;
 
     // Create our local sink
     MIDIPortRef port;
@@ -77,29 +66,27 @@ public:
 
     if (result != noErr)
     {
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration, "midi_in_core::open_port: error creating macOS MIDI input port: "
+          this->configuration, "error creating macOS MIDI input port: " + std::to_string(result));
-                                   + std::to_string(result));
+      return from_osstatus(result);
-      return false;
     }
 
     // Make the connection.
     if (result = MIDIPortConnectSource(port, source, nullptr); result != noErr)
     {
       MIDIPortDispose(port);
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error connecting macOS MIDI input port.");
-          this->configuration, "midi_in_core::open_port: error connecting macOS MIDI input port.");
+      return from_osstatus(result);
-      return false;
     }
 
     // Save our api-specific port information.
     this->port = port;
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
     // Create a virtual MIDI input destination.
     MIDIEndpointRef endpoint;
@@ -111,38 +98,19 @@ public:
 
     if (result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
           this->configuration,
-          "midi_in_core::open_virtual_port: error creating virtual macOS MIDI "
+          "error creating virtual macOS MIDI "
           "destination.");
-      return false;
+      return from_osstatus(result);
     }
 
     // Save our api-specific connection information.
     this->endpoint = endpoint;
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    if (this->endpoint)
-    {
-      MIDIEndpointDispose(this->endpoint);
-      this->endpoint = 0;
-    }
-
-    if (this->port)
-    {
-      MIDIPortDispose(this->port);
-      this->port = 0;
-    }
-  }
-
-  void set_timestamp(
-      [[maybe_unused]] const MIDIEventPacket& packet,
-      [[maybe_unused]] libremidi::ump& msg) noexcept
-  {
-  }
 
   timestamp absolute_timestamp() const noexcept override
   {
@@ -151,33 +119,28 @@ public:
 
   void midiInputCallback(const MIDIEventList* list, void* /*srcRef*/)
   {
-    unsigned short nBytes{};
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = true,
+        .absolute_is_monotonic = false,
+        .has_samples = false,
+    };
 
     const MIDIEventPacket* packet = &list->packet[0];
     for (unsigned int i = 0; i < list->numPackets; ++i)
     {
-      nBytes = packet->wordCount;
+      if (packet->wordCount > 0)
-      if (nBytes == 0)
       {
-        packet = MIDIEventPacketNext(packet);
+        auto to_ns = [packet] { return time_in_nanos(packet->timeStamp); };
-        continue;
+        m_processing.on_bytes_multi(
+            {packet->words, packet->words + packet->wordCount},
+            m_processing.timestamp<timestamp_info>(to_ns, 0));
       }
 
-      libremidi::ump msg;
-      coremidi_data::set_timestamp(*this, packet->timeStamp, msg.timestamp);
-
-      if (packet->wordCount <= 4)
-      {
-        std::copy_n(packet->words, packet->wordCount, msg.data);
-        configuration.on_message(std::move(msg));
-      }
-      last_time = time_in_nanos(packet->timeStamp);
-
       packet = MIDIEventPacketNext(packet);
     }
   }
 
-  unsigned long long last_time{};
+  midi2::input_state_machine m_processing{this->configuration};
 };
 
 }

include/libremidi/backends/coremidi_ump/midi_out.hpp

@@ -5,14 +5,15 @@
 #include <libremidi/detail/midi_out.hpp>
 #include <libremidi/detail/ump_stream.hpp>
 
-namespace libremidi::coremidi_ump
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
 class midi_out_impl final
     : public midi2::out_api
-    , private coremidi_data
+    , public coremidi_data
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : libremidi::output_configuration
       , coremidi_ump::output_configuration
@@ -25,11 +26,13 @@ public:
   {
     if (auto result = init_client(configuration); result != noErr)
     {
-      error<driver_error>(
+      libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "midi_out_impl: error creating MIDI client object: " + std::to_string(result));
+      client_open_ = from_osstatus(result);
       return;
     }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_impl()
@@ -39,64 +42,39 @@ public:
     if (this->endpoint)
       MIDIEndpointDispose(this->endpoint);
 
-    close_client();
+    close_client(*this);
-  }
-
-  void close_client()
-  {
-    if (!configuration.context)
-      MIDIClientDispose(this->client);
-  }
-
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_impl: set_client_name unsupported");
-  }
-  void set_port_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_impl: set_port_name unsupported");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI_UMP; }
 
-  bool open_port(const output_port& info, std::string_view portName) override
+  stdx::error open_port(const output_port& info, std::string_view portName) override
   {
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, false);
 
     // Find where we want to send
     auto destination = locate_object(*this, info, kMIDIObjectType_Destination);
     if (destination == 0)
-      return false;
+      return std::errc::invalid_argument;
 
     // Create our local source
     MIDIPortRef port;
     OSStatus result = MIDIOutputPortCreate(this->client, toCFString(portName).get(), &port);
     if (result != noErr)
     {
-      close_client();
+      close_client(*this);
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating macOS MIDI output port.");
-          this->configuration, "midi_out_impl::open_port: error creating macOS MIDI output port.");
+      return from_osstatus(result);
-      return false;
     }
 
     // Save our api-specific connection information.
     this->port = port;
     this->destinationId = destination;
 
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
-    if (this->endpoint)
-    {
-      warning(
-          configuration,
-          "midi_out_impl::open_virtual_port: a virtual output port already "
-          "exists!");
-      return false;
-    }
-
     // Create a virtual MIDI output source.
     OSStatus result = MIDISourceCreateWithProtocol(
         this->client, toCFString(portName).get(), kMIDIProtocol_2_0, &this->endpoint);
@@ -104,42 +82,28 @@ public:
     if (result != noErr)
     {
       this->endpoint = 0;
-      error<driver_error>(
+      libremidi_handle_error(this->configuration, "error creating macOS virtual MIDI source.");
-          this->configuration,
+
-          "midi_out_impl::initialize: error creating macOS virtual MIDI source.");
+      return from_osstatus(result);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  void close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    if (this->endpoint)
-    {
-      MIDIEndpointDispose(this->endpoint);
-      this->endpoint = 0;
-    }
 
-    if (this->port)
+  stdx::error send_ump(const uint32_t* ump_stream, std::size_t count) override
-    {
-      MIDIPortDispose(this->port);
-      this->port = 0;
-    }
-  }
-
-  void send_ump(const uint32_t* ump_stream, std::size_t count) override
   {
     MIDIEventList* eventList = reinterpret_cast<MIDIEventList*>(m_eventListBuffer);
     MIDIEventPacket* packet = MIDIEventListInit(eventList, kMIDIProtocol_2_0);
     const MIDITimeStamp ts = LIBREMIDI_AUDIO_GET_CURRENT_HOST_TIME();
 
-    auto write_fun = [ts, &packet, &eventList](const uint32_t* ump, int bytes) {
+    auto write_fun = [ts, &packet, &eventList](const uint32_t* ump, int bytes) -> std::errc {
       packet = MIDIEventListAdd(eventList, event_list_max_size, packet, ts, bytes / 4, ump);
       if (packet)
-        return segmentation_error::no_error;
+        return std::errc{0};
       else
-        return segmentation_error::need_space;
+        return std::errc::not_enough_memory;
     };
 
     auto realloc_fun = [this, &packet, &eventList] {
@@ -148,20 +112,21 @@ public:
     };
 
     segment_ump_stream(ump_stream, count, write_fun, realloc_fun);
-    push_event_list(eventList);
+    return push_event_list(eventList);
   }
 
-  void push_event_list(MIDIEventList* eventList)
+  stdx::error push_event_list(MIDIEventList* eventList)
   {
     if (this->endpoint)
     {
       auto result = MIDIReceivedEventList(this->endpoint, eventList);
       if (result != noErr)
       {
-        warning(
+        libremidi_handle_warning(
             this->configuration,
-            "midi_out_core::send_message: error sending MIDI to virtual "
+            "error sending MIDI to virtual "
             "destinations.");
+        return std::errc::io_error;
       }
     }
 
@@ -170,11 +135,11 @@ public:
       auto result = MIDISendEventList(this->port, this->destinationId, eventList);
       if (result != noErr)
       {
-        warning(
+        libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-            this->configuration,
+        return std::errc::io_error;
-            "midi_out_core::send_message: error sending MIDI message to port.");
       }
     }
+    return stdx::error{};
   }
 
   MIDIEndpointRef destinationId{};

include/libremidi/backends/coremidi_ump/observer.hpp

@@ -1,12 +1,22 @@
 #pragma once
 #include <libremidi/backends/coremidi/observer.hpp>
+#include <libremidi/backends/coremidi_ump/config.hpp>
 
-namespace libremidi::coremidi_ump
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
 
 class observer_impl final : public libremidi::observer_core
 {
-  using observer_core::observer_core;
+public:
+  explicit observer_impl(
+      libremidi::observer_configuration&& conf, coremidi_ump::observer_configuration&& apiconf)
+      : observer_core{
+            std::move(conf),
+            coremidi_observer_configuration{apiconf.client_name, apiconf.on_create_context}}
+  {
+    finish_init();
+  }
+
   libremidi::API get_current_api() const noexcept override { return libremidi::API::COREMIDI_UMP; }
 };
 

include/libremidi/backends/dummy.hpp

@@ -5,7 +5,9 @@
 #include <libremidi/detail/midi_out.hpp>
 #include <libremidi/detail/observer.hpp>
 
-namespace libremidi
+#include <string_view>
+
+NAMESPACE_LIBREMIDI
 {
 class observer_dummy : public observer_api
 {
@@ -23,20 +25,24 @@ class midi_in_dummy final
     , public error_handler
 {
 public:
-  explicit midi_in_dummy(const auto& configuration, const auto&)
+  explicit midi_in_dummy(const input_configuration& configuration, const input_api_configuration&)
   {
-    warning(configuration, "midi_in_dummy: This class provides no functionality.");
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
+  }
+  explicit midi_in_dummy(
+      const ump_input_configuration& configuration, const input_api_configuration&)
+  {
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::DUMMY; }
-  bool open_port(const input_port& /*pt*/, std::string_view /*local_port_name*/) override
+  stdx::error open_port(const input_port& /*pt*/, std::string_view /*local_port_name*/) override
   {
-    return true;
+    return stdx::error{};
   }
-  bool open_virtual_port(std::string_view /*portName*/) override { return true; }
+  stdx::error open_virtual_port(std::string_view /*portName*/) override { return stdx::error{}; }
-  void close_port() override { }
+  stdx::error close_port() override { return stdx::error{}; }
-  void set_client_name(std::string_view /*clientName*/) override { }
+  stdx::error set_port_name(std::string_view /*portName*/) override { return stdx::error{}; }
-  void set_port_name(std::string_view /*portName*/) override { }
   timestamp absolute_timestamp() const noexcept override { return 0; }
 };
 
@@ -45,22 +51,25 @@ class midi_out_dummy final
     , public error_handler
 {
 public:
-  explicit midi_out_dummy(const auto& configuration, const auto&)
+  explicit midi_out_dummy(
+      const output_configuration& configuration, const output_api_configuration&)
   {
-    warning(configuration, "midi_out_dummy: This class provides no functionality.");
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::DUMMY; }
-  bool open_port(const output_port& /*pt*/, std::string_view /*local_port_name*/) override
+  stdx::error open_port(const output_port& /*pt*/, std::string_view /*local_port_name*/) override
   {
-    return true;
+    return stdx::error{};
   }
-  bool open_virtual_port(std::string_view /*portName*/) override { return true; }
+  stdx::error open_virtual_port(std::string_view /*portName*/) override { return stdx::error{}; }
 
-  void close_port() override { }
+  stdx::error close_port() override { return stdx::error{}; }
-  void set_client_name(std::string_view /*clientName*/) override { }
+  stdx::error set_port_name(std::string_view /*portName*/) override { return stdx::error{}; }
-  void set_port_name(std::string_view /*portName*/) override { }
+  stdx::error send_message(const unsigned char* /*message*/, size_t /*size*/) override
-  void send_message(const unsigned char* /*message*/, size_t /*size*/) override { }
+  {
+    return stdx::error{};
+  }
 };
 
 struct dummy_backend
@@ -72,8 +81,8 @@ struct dummy_backend
   using midi_out_configuration = dummy_configuration;
   using midi_observer_configuration = dummy_configuration;
   static const constexpr auto API = libremidi::API::DUMMY;
-  static const constexpr auto name = "dummy";
+  static const constexpr std::string_view name = "dummy";
-  static const constexpr auto display_name = "Dummy";
+  static const constexpr std::string_view display_name = "Dummy";
 
   static constexpr inline bool available() noexcept { return true; }
 };

include/libremidi/backends/emscripten.hpp

@@ -7,7 +7,9 @@
   #include <libremidi/backends/emscripten/midi_out.hpp>
   #include <libremidi/backends/emscripten/observer.hpp>
 
-namespace libremidi
+  #include <string_view>
+
+NAMESPACE_LIBREMIDI
 {
 
 struct emscripten_backend
@@ -19,8 +21,8 @@ struct emscripten_backend
   using midi_out_configuration = emscripten_output_configuration;
   using midi_observer_configuration = emscripten_observer_configuration;
   static const constexpr auto API = libremidi::API::WEBMIDI;
-  static const constexpr auto name = "webmidi";
+  static const constexpr std::string_view name = "webmidi";
-  static const constexpr auto display_name = "WebMIDI";
+  static const constexpr std::string_view display_name = "WebMIDI";
 
   static constexpr inline bool available() noexcept { return true; }
 };

include/libremidi/backends/emscripten/config.hpp

@@ -1,7 +1,7 @@
 #pragma once
 #include <libremidi/config.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 struct emscripten_input_configuration

include/libremidi/backends/emscripten/helpers.hpp

@@ -3,7 +3,7 @@
 
 #include <string>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 namespace webmidi_helpers
 {

include/libremidi/backends/emscripten/midi_access.hpp

@@ -16,7 +16,7 @@ EMSCRIPTEN_KEEPALIVE
 void libremidi_devices_input(int port, double timestamp, int len, char* bytes);
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 namespace webmidi_helpers
 {
@@ -37,16 +37,25 @@ public:
 
   int input_count() const noexcept
   {
+    if (!available())
+      return 0;
+
     return EM_ASM_INT(return globalThis.__libreMidi_currentInputs.length;);
   }
 
   int output_count() const noexcept
   {
+    if (!available())
+      return 0;
+
     return EM_ASM_INT(return globalThis.__libreMidi_currentOutputs.length;);
   }
 
   void load_current_infos() noexcept
   {
+    if (!available())
+      return;
+
 #define get_js_string(variable_to_read, ...) \
   (char*)EM_ASM_INT(                            \
         {                                         \
@@ -204,8 +213,11 @@ public:
     }
   }
 
-  void send_message(int port_index, const char* bytes, int len)
+  stdx::error send_message(int port_index, const char* bytes, int len)
   {
+    if (!available())
+      return std::errc::operation_not_supported;
+
     const auto& id = m_current_outputs[port_index].id;
     EM_ASM(
         {
@@ -216,6 +228,8 @@ public:
           output.send(Array.from(bytes));
         },
         bytes, len, id.c_str());
+
+    return stdx::error{};
   }
 
   const std::vector<device_information>& inputs() const noexcept { return m_current_inputs; }
@@ -248,6 +262,9 @@ private:
 
   void start_stream(int port_index)
   {
+    if (!available())
+      return;
+
     // Isn't life great...
     // https://github.com/Planeshifter/emscripten-examples/tree/master/01_PassingArrays
     const auto& id = m_current_inputs[port_index].id;
@@ -282,6 +299,9 @@ private:
 
   void stop_stream(int port_index)
   {
+    if (!available())
+      return;
+
     const auto& id = m_current_inputs[port_index].id;
     EM_ASM(const id = UTF8ToString($1);
 

include/libremidi/backends/emscripten/midi_in.cpp

@@ -5,18 +5,20 @@
 
   #include <chrono>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 LIBREMIDI_INLINE midi_in_emscripten::midi_in_emscripten(
     input_configuration&& conf, emscripten_input_configuration&& apiconf)
     : configuration{std::move(conf), std::move(apiconf)}
 {
+  client_open_ = stdx::error{};
 }
 
 LIBREMIDI_INLINE midi_in_emscripten::~midi_in_emscripten()
 {
   // Close a connection if it exists.
   midi_in_emscripten::close_port();
+  client_open_ = std::errc::not_connected;
 }
 
 LIBREMIDI_INLINE libremidi::API midi_in_emscripten::get_current_api() const noexcept
@@ -24,49 +26,34 @@ LIBREMIDI_INLINE libremidi::API midi_in_emscripten::get_current_api() const noex
   return libremidi::API::WEBMIDI;
 }
 
-LIBREMIDI_INLINE bool midi_in_emscripten::open_port(int portNumber, std::string_view)
+LIBREMIDI_INLINE stdx::error midi_in_emscripten::open_port(int portNumber, std::string_view)
 {
   auto& midi = webmidi_helpers::midi_access_emscripten::instance();
 
   if (portNumber < 0 || portNumber >= midi.input_count())
   {
-    error<no_devices_found_error>(
+    libremidi_handle_error(this->configuration, "no MIDI output sources found.");
-        this->configuration, "midi_in_emscripten::open_port: no MIDI output sources found.");
+    return std::errc::invalid_argument;
-    return false;
   }
 
   midi.open_input(portNumber, *this);
-  portNumber_ = portNumber;
+  m_portNumber = portNumber;
-  return true;
+  return stdx::error{};
 }
 
-LIBREMIDI_INLINE bool
+LIBREMIDI_INLINE stdx::error
 midi_in_emscripten::open_port(const libremidi::input_port& p, std::string_view nm)
 {
   return open_port(p.port, nm);
 }
 
-LIBREMIDI_INLINE bool midi_in_emscripten::open_virtual_port(std::string_view)
+LIBREMIDI_INLINE stdx::error midi_in_emscripten::close_port()
-{
-  warning(configuration, "midi_in_emscripten::open_virtual_port: unsupported.");
-  return false;
-}
-
-LIBREMIDI_INLINE void midi_in_emscripten::close_port()
 {
   auto& midi = webmidi_helpers::midi_access_emscripten::instance();
 
-  midi.close_input(portNumber_, *this);
+  midi.close_input(m_portNumber, *this);
-}
 
-LIBREMIDI_INLINE void midi_in_emscripten::set_client_name(std::string_view)
+  return stdx::error{};
-{
-  warning(configuration, "midi_in_emscripten::set_client_name: unsupported.");
-}
-
-LIBREMIDI_INLINE void midi_in_emscripten::set_port_name(std::string_view)
-{
-  warning(configuration, "midi_in_emscripten::set_port_name: unsupported.");
 }
 
 LIBREMIDI_INLINE int64_t midi_in_emscripten::absolute_timestamp() const noexcept

include/libremidi/backends/emscripten/midi_in.hpp

@@ -4,7 +4,7 @@
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/midi_stream_decoder.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class midi_in_emscripten final
     : public midi1::in_api
@@ -22,19 +22,16 @@ public:
 
   libremidi::API get_current_api() const noexcept override;
 
-  bool open_port(int portNumber, std::string_view);
+  stdx::error open_port(int portNumber, std::string_view);
-  bool open_port(const input_port& p, std::string_view) override;
+  stdx::error open_port(const input_port& p, std::string_view) override;
-  bool open_virtual_port(std::string_view) override;
+  stdx::error close_port() override;
-  void close_port() override;
 
-  void set_client_name(std::string_view clientName) override;
-  void set_port_name(std::string_view portName) override;
   timestamp absolute_timestamp() const noexcept override;
 
   void on_input(double ts, unsigned char* begin, unsigned char* end);
 
 private:
-  int portNumber_{};
+  int m_portNumber{};
 
   midi1::input_state_machine m_processing{this->configuration};
 };

include/libremidi/backends/emscripten/midi_out.cpp

@@ -2,18 +2,20 @@
   #include <libremidi/backends/emscripten/midi_access.hpp>
   #include <libremidi/backends/emscripten/midi_out.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 LIBREMIDI_INLINE midi_out_emscripten::midi_out_emscripten(
     output_configuration&& conf, emscripten_output_configuration&& apiconf)
     : configuration{std::move(conf), std::move(apiconf)}
 {
+  client_open_ = stdx::error{};
 }
 
 LIBREMIDI_INLINE midi_out_emscripten::~midi_out_emscripten()
 {
   // Close a connection if it exists.
   midi_out_emscripten::close_port();
+  client_open_ = std::errc::not_connected;
 }
 
 LIBREMIDI_INLINE libremidi::API midi_out_emscripten::get_current_api() const noexcept
@@ -21,54 +23,43 @@ LIBREMIDI_INLINE libremidi::API midi_out_emscripten::get_current_api() const noe
   return libremidi::API::WEBMIDI;
 }
 
-LIBREMIDI_INLINE bool midi_out_emscripten::open_port(unsigned int portNumber, std::string_view)
+LIBREMIDI_INLINE stdx::error midi_out_emscripten::open_port(int portNumber, std::string_view)
 {
   auto& midi = webmidi_helpers::midi_access_emscripten::instance();
 
   if (portNumber >= midi.output_count())
   {
-    error<no_devices_found_error>(
+    libremidi_handle_error(this->configuration, "no MIDI output sources found.");
-        this->configuration, "midi_out_emscripten::open_port: no MIDI output sources found.");
+    return std::errc::invalid_argument;
-    return false;
   }
 
-  portNumber_ = portNumber;
+  m_portNumber = portNumber;
-  return true;
+  return stdx::error{};
 }
 
-LIBREMIDI_INLINE bool midi_out_emscripten::open_port(const output_port& p, std::string_view nm)
+LIBREMIDI_INLINE stdx::error
+midi_out_emscripten::open_port(const output_port& p, std::string_view nm)
 {
   return open_port(p.port, nm);
 }
 
-LIBREMIDI_INLINE void midi_out_emscripten::close_port() { }
+LIBREMIDI_INLINE stdx::error midi_out_emscripten::close_port()
-
-LIBREMIDI_INLINE void midi_out_emscripten::set_client_name(std::string_view clientName)
 {
-  warning(configuration, "midi_out_emscripten::set_client_name: unsupported.");
+  return stdx::error{};
 }
 
-LIBREMIDI_INLINE void midi_out_emscripten::set_port_name(std::string_view portName)
+LIBREMIDI_INLINE stdx::error
+midi_out_emscripten::send_message(const unsigned char* message, size_t size)
 {
-  warning(configuration, "midi_out_emscripten::set_port_name: unsupported.");
+  if (m_portNumber < 0)
-}
+    libremidi_handle_error(
-
-LIBREMIDI_INLINE bool midi_out_emscripten::open_virtual_port(std::string_view)
-{
-  warning(configuration, "midi_in_emscripten::open_virtual_port: unsupported.");
-  return false;
-}
-
-LIBREMIDI_INLINE void midi_out_emscripten::send_message(const unsigned char* message, size_t size)
-{
-  if (portNumber_ < 0)
-    error<invalid_use_error>(
         this->configuration,
-        "midi_out_emscripten::send_message: trying to send a message without an open "
+        "trying to send a message without an open "
         "port.");
 
   webmidi_helpers::midi_access_emscripten::instance().send_message(
-      portNumber_, reinterpret_cast<const char*>(message), size);
+      m_portNumber, reinterpret_cast<const char*>(message), size);
+  return stdx::error{};
 }
 }
 #endif

include/libremidi/backends/emscripten/midi_out.hpp

@@ -3,7 +3,7 @@
 #include <libremidi/backends/emscripten/helpers.hpp>
 #include <libremidi/detail/midi_out.hpp>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class midi_out_emscripten final
     : public midi1::out_api
@@ -21,17 +21,13 @@ public:
 
   libremidi::API get_current_api() const noexcept override;
 
-  bool open_port(unsigned int portNumber, std::string_view);
+  stdx::error open_port(int portNumber, std::string_view);
-  bool open_port(const output_port& p, std::string_view) override;
+  stdx::error open_port(const output_port& p, std::string_view) override;
-  bool open_virtual_port(std::string_view) override;
+  stdx::error close_port() override;
-  void close_port() override;
 
-  void set_client_name(std::string_view clientName) override;
+  stdx::error send_message(const unsigned char* message, size_t size) override;
-  void set_port_name(std::string_view portName) override;
-
-  void send_message(const unsigned char* message, size_t size) override;
 
 private:
-  int portNumber_{-1};
+  int m_portNumber{-1};
 };
 }

include/libremidi/backends/emscripten/observer.cpp

@@ -4,7 +4,7 @@
 
   #include <cassert>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 LIBREMIDI_INLINE observer_emscripten::observer_emscripten(
     observer_configuration&& conf, emscripten_observer_configuration&& apiconf)
@@ -42,7 +42,8 @@ static auto to_port_info(int index, const webmidi_helpers::device_information& d
     -> std::conditional_t<Input, input_port, output_port>
 {
   return {
-      {.client = 0,
+      {.api = libremidi::API::WEBMIDI,
+       .client = 0,
        .port = (uint64_t)index,
        .manufacturer = "",
        .device_name = "",

include/libremidi/backends/emscripten/observer.hpp

@@ -5,7 +5,7 @@
 
 #include <vector>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class observer_emscripten final : public observer_api
 {

include/libremidi/backends/jack.hpp

@@ -3,6 +3,8 @@
 #include <libremidi/backends/jack/midi_out.hpp>
 #include <libremidi/backends/jack/observer.hpp>
 
+#include <string_view>
+
 //*********************************************************************//
 //  API: UNIX JACK
 //
@@ -11,7 +13,7 @@
 //
 //  *********************************************************************//
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct jack_backend
 {
@@ -22,8 +24,8 @@ struct jack_backend
   using midi_out_configuration = jack_output_configuration;
   using midi_observer_configuration = jack_observer_configuration;
   static const constexpr auto API = libremidi::API::JACK_MIDI;
-  static const constexpr auto name = "jack";
+  static const constexpr std::string_view name = "jack";
-  static const constexpr auto display_name = "JACK";
+  static const constexpr std::string_view display_name = "JACK";
 
   static inline bool available() noexcept
   {

include/libremidi/backends/jack/config.hpp

@@ -1,7 +1,6 @@
 #pragma once
 #include <libremidi/config.hpp>
 
-#include <cinttypes>
 #include <cstdint>
 #include <functional>
 #include <string>
@@ -12,7 +11,7 @@ typedef uint32_t jack_nframes_t;
 typedef int (*JackProcessCallback)(jack_nframes_t nframes, void* arg);
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 using jack_callback_function = std::function<void(int nframes)>;
 struct jack_callback
@@ -25,8 +24,8 @@ struct jack_input_configuration
   std::string client_name = "libremidi client";
 
   jack_client_t* context{};
-  std::function<void(jack_callback)> set_process_func;
+  std::function<void(jack_callback)> set_process_func{};
-  std::function<void(int64_t)> clear_process_func;
+  std::function<void(int64_t)> clear_process_func{};
 };
 
 struct jack_output_configuration
@@ -34,8 +33,8 @@ struct jack_output_configuration
   std::string client_name = "libremidi client";
 
   jack_client_t* context{};
-  std::function<void(jack_callback)> set_process_func;
+  std::function<void(jack_callback)> set_process_func{};
-  std::function<void(int64_t)> clear_process_func;
+  std::function<void(int64_t)> clear_process_func{};
 
   int32_t ringbuffer_size = 16384;
   bool direct = false;

include/libremidi/backends/jack/error_domain.hpp

@@ -0,0 +1,78 @@
+#pragma once
+#include <libremidi/error.hpp>
+
+#if __has_include(<weakjack/weak_libjack.h>)
+  #include <weakjack/weak_libjack.h>
+#elif __has_include(<weak_libjack.h>)
+  #include <weak_libjack.h>
+#elif __has_include(<jack/jack.h> )
+  #include <jack/jack.h>
+  #include <jack/midiport.h>
+  #include <jack/ringbuffer.h>
+#endif
+
+NAMESPACE_LIBREMIDI
+{
+struct jack_error_domain : public stdx::error_domain
+{
+public:
+  constexpr jack_error_domain() noexcept
+      : error_domain{{0xc714ea32b705080aULL, 0xe409a437daf5f921ULL}}
+  {
+  }
+
+  stdx::string_ref name() const noexcept override { return "jack"; }
+
+  bool equivalent(const stdx::error& lhs, const stdx::error& rhs) const noexcept override
+  {
+    if (lhs.domain() == rhs.domain())
+      return error_cast<jack_status_t>(lhs) == error_cast<jack_status_t>(rhs);
+
+    return false;
+  }
+
+  stdx::string_ref message(const stdx::error& e) const noexcept override
+  {
+    const auto status = error_cast<jack_status_t>(e);
+    if (status == jack_status_t{})
+      return "Success";
+
+    if (status & JackInvalidOption)
+      return "The operation contained an invalid or unsupported option";
+    if (status & JackServerFailed)
+      return "Unable to connect to the JACK server";
+    if (status & JackServerError)
+      return "Communication error with the JACK server";
+    if (status & JackNoSuchClient)
+      return "Requested client does not exist";
+    if (status & JackLoadFailure)
+      return "Unable to load internal client";
+    if (status & JackInitFailure)
+      return "Unable to initialize client";
+    if (status & JackShmFailure)
+      return "Unable to access shared memory";
+    if (status & JackVersionError)
+      return "Client's protocol version does not match";
+    if (status & JackBackendError)
+      return "Backend error";
+    if (status & JackClientZombie)
+      return "Client zombified failure";
+    if (status & JackFailure)
+      return "Failure";
+    if (status & JackNameNotUnique)
+      return "The desired client name was not unique";
+
+    // Can't happen in libremidi as we set JackNoStartServer
+    if (status & JackServerStarted)
+      return "Server was started";
+
+    return "Unknown JACK status code";
+  }
+};
+
+inline stdx::error from_jack_status(jack_status_t ret) noexcept
+{
+  static constexpr jack_error_domain domain{};
+  return {ret, domain};
+}
+}

include/libremidi/backends/jack/helpers.hpp

@@ -1,21 +1,15 @@
 #pragma once
 
-#if __has_include(<weakjack/weak_libjack.h>)
+#include <libremidi/backends/jack/error_domain.hpp>
-  #include <weakjack/weak_libjack.h>
-#elif __has_include(<weak_libjack.h>)
-  #include <weak_libjack.h>
-#elif __has_include(<jack/jack.h> )
-  #include <jack/jack.h>
-  #include <jack/midiport.h>
-  #include <jack/ringbuffer.h>
-#endif
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/semaphore.hpp>
 
 #include <atomic>
-#include <semaphore>
+#include <cstdint>
+#include <cstring>
+#include <memory>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct jack_client
 {
@@ -47,31 +41,32 @@ struct jack_client
     }
   }
 
-  template <bool Input>
+  template <bool Input, libremidi::API Api>
   static auto to_port_info(jack_client_t* client, jack_port_t* port)
       -> std::conditional_t<Input, input_port, output_port>
   {
     return {{
+        .api = Api,
         .client = reinterpret_cast<std::uintptr_t>(client),
         .port = 0,
         .manufacturer = "",
-        .device_name = "",
+        .device_name = jack_get_client_name(client),
         .port_name = jack_port_name(port),
         .display_name = get_port_display_name(port),
     }};
   }
 
-  template <bool Input>
+  template <bool Input, libremidi::API Api>
-  static auto
+  static auto get_ports(
-  get_ports(jack_client_t* client, const char* pattern, const JackPortFlags flags) noexcept
+      jack_client_t* client, const char* pattern, const char* type, const JackPortFlags flags,
-      -> std::vector<std::conditional_t<Input, input_port, output_port>>
+      bool midi2) noexcept -> std::vector<std::conditional_t<Input, input_port, output_port>>
   {
     std::vector<std::conditional_t<Input, input_port, output_port>> ret;
 
     if (!client)
       return {};
 
-    const char** ports = jack_get_ports(client, pattern, JACK_DEFAULT_MIDI_TYPE, flags);
+    const char** ports = jack_get_ports(client, pattern, type, flags);
 
     if (ports == nullptr)
       return {};
@@ -81,7 +76,11 @@ struct jack_client
     {
       // FIXME this does not take into account filtering sw / hw ports
       auto port = jack_port_by_name(client, ports[i]);
-      ret.push_back(to_port_info<Input>(client, port));
+      if (port)
+      {
+        if (bool(midi2) == bool(jack_port_flags(port) & 0x20))
+          ret.push_back(to_port_info<Input, Api>(client, port));
+      }
       i++;
     }
 
@@ -140,7 +139,7 @@ struct jack_helpers : jack_client
           {.token = this_instance,
            .callback = [&self, p = std::weak_ptr{this->port.impl}](jack_nframes_t nf) -> int {
         if (auto pt = p.lock())
-               if (auto ppt = pt->load())
+          if (pt->load())
             self.process(nf);
 
         self.thread_lock.check_client_released();
@@ -157,9 +156,13 @@ struct jack_helpers : jack_client
           = jack_client_open(configuration.client_name.c_str(), JackNoStartServer, &status);
       if (this->client != nullptr)
       {
-        jack_set_process_callback(
+        if (status & JackNameNotUnique)
-            this->client,
+        {
-            +[](jack_nframes_t nf, void* ctx) -> int {
+          self.libremidi_handle_warning(
+              self.configuration, "JACK client with the same name already exists, renamed.");
+        }
+
+        jack_set_process_callback(this->client, +[](jack_nframes_t nf, void* ctx) -> int {
           auto& self = *static_cast<Self*>(ctx);
           jack_port_t* port = self.port;
 
@@ -171,8 +174,7 @@ struct jack_helpers : jack_client
 
           self.thread_lock.check_client_released();
           return 0;
-            },
+        }, &self);
-            &self);
         jack_activate(this->client);
       }
       return status;
@@ -192,9 +194,12 @@ struct jack_helpers : jack_client
 
     if (this->client && !self.configuration.context)
       jack_client_close(this->client);
+
+    self.client_open_ = std::errc::not_connected;
   }
 
-  bool create_local_port(const auto& self, std::string_view portName, JackPortFlags flags)
+  stdx::error create_local_port(
+      const auto& self, std::string_view portName, const char* type, JackPortFlags flags)
   {
     // full name: "client_name:port_name\0"
     if (portName.empty())
@@ -203,29 +208,27 @@ struct jack_helpers : jack_client
     if (self.configuration.client_name.size() + portName.size() + 2u
         >= static_cast<size_t>(jack_port_name_size()))
     {
-      self.template error<invalid_use_error>(
+      self.libremidi_handle_error(self.configuration, "port name length limit exceeded");
-          self.configuration, "JACK: port name length limit exceeded");
+      return std::errc::invalid_argument;
-      return false;
     }
 
     if (!this->port)
     {
-      this->port
+      this->port = jack_port_register(this->client, portName.data(), type, flags, 0);
-          = jack_port_register(this->client, portName.data(), JACK_DEFAULT_MIDI_TYPE, flags, 0);
     }
 
     if (!this->port)
     {
-      self.template error<driver_error>(self.configuration, "JACK: error creating port");
+      self.libremidi_handle_error(self.configuration, "error creating port");
-      return false;
+      return std::errc::operation_not_supported;
     }
-    return true;
+    return stdx::error{};
   }
 
-  void do_close_port()
+  stdx::error do_close_port()
   {
     if (this->port == nullptr)
-      return;
+      return stdx::error{};
 
     // 1. Ensure that the next time the cycle runs it sees the port as nullptr
     jack_port_t* port_ptr = this->port.impl->load();
@@ -235,7 +238,81 @@ struct jack_helpers : jack_client
     this->thread_lock.prepare_release_client();
 
     // 3. Now we are sure that the client is not going to use the port anymore
-    jack_port_unregister(this->client, port_ptr);
+    int err = jack_port_unregister(this->client, port_ptr);
+    return from_errc(err);
   }
 };
+
+struct jack_queue
+{
+public:
+  static constexpr auto size_sz = sizeof(int32_t);
+
+  jack_queue() = default;
+  jack_queue(const jack_queue&) = delete;
+  jack_queue(jack_queue&&) = delete;
+  jack_queue& operator=(const jack_queue&) = delete;
+
+  jack_queue& operator=(jack_queue&& other) noexcept
+  {
+    ringbuffer = other.ringbuffer;
+    ringbuffer_space = other.ringbuffer_space;
+    other.ringbuffer = nullptr;
+    return *this;
+  }
+
+  explicit jack_queue(int64_t sz) noexcept
+  {
+    ringbuffer = jack_ringbuffer_create(sz);
+    ringbuffer_space = jack_ringbuffer_write_space(ringbuffer);
+  }
+
+  ~jack_queue() noexcept
+  {
+    if (ringbuffer)
+      jack_ringbuffer_free(ringbuffer);
+  }
+
+  stdx::error write(const unsigned char* data, int64_t sz) const noexcept
+  {
+    if (static_cast<std::size_t>(sz + size_sz) > ringbuffer_space)
+      return std::errc::no_buffer_space;
+
+    while (jack_ringbuffer_write_space(ringbuffer) < sz + size_sz)
+      sched_yield();
+
+    jack_ringbuffer_write(ringbuffer, reinterpret_cast<char*>(&sz), size_sz);
+    jack_ringbuffer_write(ringbuffer, reinterpret_cast<const char*>(data), sz);
+
+    return stdx::error{};
+  }
+
+  void read(void* jack_events) const noexcept
+  {
+    int32_t sz;
+    while (jack_ringbuffer_peek(ringbuffer, reinterpret_cast<char*>(&sz), size_sz) == size_sz
+           && jack_ringbuffer_read_space(ringbuffer) >= size_sz + sz)
+    {
+      jack_ringbuffer_read_advance(ringbuffer, size_sz);
+
+      if (auto midi = jack_midi_event_reserve(jack_events, 0, sz))
+        jack_ringbuffer_read(ringbuffer, reinterpret_cast<char*>(midi), sz);
+      else
+        jack_ringbuffer_read_advance(ringbuffer, sz);
+    }
+  }
+
+  jack_ringbuffer_t* ringbuffer{};
+  std::size_t ringbuffer_space{}; // actual writable size, usually 1 less than ringbuffer
+};
+
+struct jack_midi1
+{
+  static constexpr const char* port_type = "8 bit raw midi";
+};
+
+struct jack_midi2
+{
+  static constexpr const char* port_type = "32 bit raw UMP";
+};
 }

include/libremidi/backends/jack/midi_in.hpp

@@ -4,16 +4,16 @@
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/midi_stream_decoder.hpp>
 
-#include <chrono>
+NAMESPACE_LIBREMIDI
-
-namespace libremidi
 {
 class midi_in_jack final
     : public midi1::in_api
     , public jack_helpers
+    , public jack_midi1
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : input_configuration
       , jack_input_configuration
@@ -24,8 +24,14 @@ public:
       : configuration{std::move(conf), std::move(apiconf)}
   {
     auto status = connect(*this);
-    if (status != jack_status_t{})
+    if (!this->client)
-      warning(configuration, "midi_in_jack: " + std::to_string((int)jack_status_t{}));
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_in_jack() override
@@ -35,39 +41,36 @@ public:
     disconnect(*this);
   }
 
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_in_jack: set_client_name unsupported");
-  }
-
   libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_MIDI; }
 
-  bool open_port(const input_port& port, std::string_view portName) override
+  stdx::error open_port(const input_port& port, std::string_view portName) override
   {
-    if (!create_local_port(*this, portName, JackPortIsInput))
+    if (auto err = create_local_port(*this, portName, port_type, JackPortIsInput);
-      return false;
+        err != stdx::error{})
+      return err;
 
-    if (auto ret = jack_connect(this->client, port.port_name.c_str(), jack_port_name(this->port));
+    if (int err = jack_connect(this->client, port.port_name.c_str(), jack_port_name(this->port));
-        ret != 0)
+        err != 0 && err != EEXIST)
     {
-      error<invalid_parameter_error>(
+      libremidi_handle_error(
-          configuration, "JACK: could not connect to port: " + port.port_name + " -> "
+          configuration,
-                             + jack_port_name(this->port));
+          "could not connect to port: " + port.port_name + " -> " + jack_port_name(this->port));
-      return false;
+      return from_errc(err);
     }
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
-    return create_local_port(*this, portName, JackPortIsInput);
+    return create_local_port(*this, portName, port_type, JackPortIsInput);
   }
 
-  void close_port() override { return do_close_port(); }
+  stdx::error close_port() override { return do_close_port(); }
 
-  void set_port_name(std::string_view portName) override
+  stdx::error set_port_name(std::string_view portName) override
   {
-    jack_port_rename(this->client, this->port, portName.data());
+    int ret = jack_port_rename(this->client, this->port, portName.data());
+    return from_errc(ret);
   }
 
   timestamp absolute_timestamp() const noexcept override
@@ -93,8 +96,8 @@ public:
         this->client, &current_frames, &current_usecs, &next_usecs, &period_usecs);
 
     // We have midi events in buffer
-    uint32_t evCount = jack_midi_get_event_count(buff);
+    uint32_t ev_count = jack_midi_get_event_count(buff);
-    for (uint32_t j = 0; j < evCount; j++)
+    for (uint32_t j = 0; j < ev_count; j++)
     {
       jack_midi_event_t event{};
       jack_midi_event_get(&event, buff, j);

include/libremidi/backends/jack/midi_out.hpp

@@ -3,77 +3,16 @@
 #include <libremidi/backends/jack/helpers.hpp>
 #include <libremidi/detail/midi_out.hpp>
 
-#include <semaphore>
+NAMESPACE_LIBREMIDI
-
-namespace libremidi
 {
-struct jack_queue
-{
-public:
-  static constexpr auto size_sz = sizeof(int32_t);
-
-  jack_queue() = default;
-  jack_queue(const jack_queue&) = delete;
-  jack_queue(jack_queue&&) = delete;
-  jack_queue& operator=(const jack_queue&) = delete;
-
-  jack_queue& operator=(jack_queue&& other) noexcept
-  {
-    ringbuffer = other.ringbuffer;
-    ringbuffer_space = other.ringbuffer_space;
-    other.ringbuffer = nullptr;
-    return *this;
-  }
-
-  explicit jack_queue(int64_t sz) noexcept
-  {
-    ringbuffer = jack_ringbuffer_create(sz);
-    ringbuffer_space = jack_ringbuffer_write_space(ringbuffer);
-  }
-
-  ~jack_queue() noexcept
-  {
-    if (ringbuffer)
-      jack_ringbuffer_free(ringbuffer);
-  }
-
-  void write(const unsigned char* data, int64_t sz) const noexcept
-  {
-    if (static_cast<std::size_t>(sz + size_sz) > ringbuffer_space)
-      return;
-
-    while (jack_ringbuffer_write_space(ringbuffer) < sz + size_sz)
-      sched_yield();
-
-    jack_ringbuffer_write(ringbuffer, reinterpret_cast<char*>(&sz), size_sz);
-    jack_ringbuffer_write(ringbuffer, reinterpret_cast<const char*>(data), sz);
-  }
-
-  void read(void* jack_events) const noexcept
-  {
-    int32_t sz;
-    while (jack_ringbuffer_peek(ringbuffer, reinterpret_cast<char*>(&sz), size_sz) == size_sz
-           && jack_ringbuffer_read_space(ringbuffer) >= size_sz + sz)
-    {
-      jack_ringbuffer_read_advance(ringbuffer, size_sz);
-
-      if (auto midi = jack_midi_event_reserve(jack_events, 0, sz))
-        jack_ringbuffer_read(ringbuffer, reinterpret_cast<char*>(midi), sz);
-      else
-        jack_ringbuffer_read_advance(ringbuffer, sz);
-    }
-  }
-
-  jack_ringbuffer_t* ringbuffer{};
-  std::size_t ringbuffer_space{}; // actual writable size, usually 1 less than ringbuffer
-};
-
 class midi_out_jack
     : public midi1::out_api
     , public jack_helpers
+    , public jack_midi1
     , public error_handler
 {
 public:
+  using midi_api::client_open_;
   struct
       : output_configuration
       , jack_output_configuration
@@ -87,39 +26,36 @@ public:
 
   ~midi_out_jack() override { }
 
-  void set_client_name(std::string_view) override
-  {
-    warning(configuration, "midi_out_jack: set_client_name unsupported");
-  }
-
   libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_MIDI; }
 
-  bool open_port(const output_port& port, std::string_view portName) override
+  stdx::error open_port(const output_port& port, std::string_view portName) override
   {
-    if (!create_local_port(*this, portName, JackPortIsOutput))
+    if (auto err = create_local_port(*this, portName, port_type, JackPortIsOutput);
-      return false;
+        err != stdx::error{})
+      return err;
 
     // Connecting to the output
-    if (jack_connect(this->client, jack_port_name(this->port), port.port_name.c_str()) != 0)
+    if (int err = jack_connect(this->client, jack_port_name(this->port), port.port_name.c_str());
+        err != 0 && err != EEXIST)
     {
-      error<invalid_parameter_error>(
+      libremidi_handle_error(configuration, "could not connect to port" + port.port_name);
-          configuration, "JACK: could not connect to port" + port.port_name);
+      return from_errc(err);
-      return false;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  bool open_virtual_port(std::string_view portName) override
+  stdx::error open_virtual_port(std::string_view portName) override
   {
-    return create_local_port(*this, portName, JackPortIsOutput);
+    return create_local_port(*this, portName, port_type, JackPortIsOutput);
   }
 
-  void close_port() override { return do_close_port(); }
+  stdx::error close_port() override { return do_close_port(); }
 
-  void set_port_name(std::string_view portName) override
+  stdx::error set_port_name(std::string_view portName) override
   {
-    jack_port_rename(this->client, this->port, portName.data());
+    int ret = jack_port_rename(this->client, this->port, portName.data());
+    return from_errc(ret);
   }
 };
 
@@ -128,11 +64,17 @@ class midi_out_jack_queued final : public midi_out_jack
 public:
   midi_out_jack_queued(output_configuration&& conf, jack_output_configuration&& apiconf)
       : midi_out_jack{std::move(conf), std::move(apiconf)}
-      , queue{configuration.ringbuffer_size}
+      , m_queue{configuration.ringbuffer_size}
   {
     auto status = connect(*this);
-    if (status != jack_status_t{})
+    if (!this->client)
-      warning(configuration, "midi_out_jack_queued: " + std::to_string((int)jack_status_t{}));
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
+
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_jack_queued() override
@@ -142,9 +84,9 @@ public:
     disconnect(*this);
   }
 
-  void send_message(const unsigned char* message, std::size_t size) override
+  stdx::error send_message(const unsigned char* message, std::size_t size) override
   {
-    queue.write(message, size);
+    return m_queue.write(message, size);
   }
 
   int process(jack_nframes_t nframes)
@@ -152,13 +94,13 @@ public:
     void* buff = jack_port_get_buffer(this->port, nframes);
     jack_midi_clear_buffer(buff);
 
-    this->queue.read(buff);
+    this->m_queue.read(buff);
 
     return 0;
   }
 
 private:
-  jack_queue queue;
+  jack_queue m_queue;
 };
 
 class midi_out_jack_direct final : public midi_out_jack
@@ -168,10 +110,15 @@ public:
       : midi_out_jack{std::move(conf), std::move(apiconf)}
   {
     auto status = connect(*this);
-    if (status != jack_status_t{})
+    if (!this->client)
-      warning(configuration, "midi_out_jack_direct: " + std::to_string((int)jack_status_t{}));
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
 
     buffer_size = jack_get_buffer_size(this->client);
+    client_open_ = stdx::error{};
   }
 
   ~midi_out_jack_direct() override
@@ -188,10 +135,11 @@ public:
     return 0;
   }
 
-  void send_message(const unsigned char* message, size_t size) override
+  stdx::error send_message(const unsigned char* message, size_t size) override
   {
     void* buff = jack_port_get_buffer(this->port, buffer_size);
-    jack_midi_event_write(buff, 0, message, size);
+    int ret = jack_midi_event_write(buff, 0, message, size);
+    return from_errc(ret);
   }
 
   int convert_timestamp(int64_t user) const noexcept
@@ -207,17 +155,18 @@ public:
     }
   }
 
-  void schedule_message(int64_t ts, const unsigned char* message, size_t size) override
+  stdx::error schedule_message(int64_t ts, const unsigned char* message, size_t size) override
   {
     void* buff = jack_port_get_buffer(this->port, buffer_size);
-    jack_midi_event_write(buff, convert_timestamp(ts), message, size);
+    int ret = jack_midi_event_write(buff, convert_timestamp(ts), message, size);
+    return from_errc(ret);
   }
 
   int buffer_size{};
 };
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <>
 inline std::unique_ptr<midi_out_api> make<midi_out_jack>(

include/libremidi/backends/jack/observer.hpp

@@ -5,11 +5,12 @@
 
 #include <unordered_set>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class observer_jack final
     : public observer_api
     , private jack_client
+    , public jack_midi1
     , private error_handler
 {
 public:
@@ -34,7 +35,7 @@ public:
       this->client
           = jack_client_open(configuration.client_name.c_str(), JackNoStartServer, &status);
       if (status != jack_status_t{})
-        warning(configuration, "observer_jack: " + std::to_string((int)jack_status_t{}));
+        libremidi_handle_error(configuration, std::to_string((int)status));
 
       if (this->client != nullptr)
       {
@@ -48,8 +49,7 @@ public:
   void initial_callback()
   {
     {
-      const char** ports
+      const char** ports = jack_get_ports(client, nullptr, port_type, JackPortIsOutput);
-          = jack_get_ports(client, nullptr, JACK_DEFAULT_MIDI_TYPE, JackPortIsOutput);
 
       if (ports != nullptr)
       {
@@ -70,7 +70,8 @@ public:
           {
             seen_input_ports.insert(ports[i]);
             if (this->configuration.input_added && configuration.notify_in_constructor)
-              this->configuration.input_added(to_port_info<true>(client, port));
+              this->configuration.input_added(
+                  to_port_info<true, libremidi::API::JACK_MIDI>(client, port));
           }
           i++;
         }
@@ -80,8 +81,7 @@ public:
     }
 
     {
-      const char** ports
+      const char** ports = jack_get_ports(client, nullptr, port_type, JackPortIsInput);
-          = jack_get_ports(client, nullptr, JACK_DEFAULT_MIDI_TYPE, JackPortIsInput);
 
       if (ports != nullptr)
       {
@@ -102,7 +102,8 @@ public:
           {
             seen_output_ports.insert(ports[i]);
             if (this->configuration.output_added && configuration.notify_in_constructor)
-              this->configuration.output_added(to_port_info<false>(client, port));
+              this->configuration.output_added(
+                  to_port_info<false, libremidi::API::JACK_MIDI>(client, port));
           }
           i++;
         }
@@ -119,7 +120,7 @@ public:
     if (reg)
     {
       std::string_view type = jack_port_type(port);
-      if (type != JACK_DEFAULT_MIDI_TYPE)
+      if (type != port_type)
         return;
 
       bool physical = flags & JackPortIsPhysical;
@@ -139,13 +140,15 @@ public:
       {
         seen_input_ports.insert(name);
         if (this->configuration.input_added)
-          this->configuration.input_added(to_port_info<true>(client, port));
+          this->configuration.input_added(
+              to_port_info<true, libremidi::API::JACK_MIDI>(client, port));
       }
       else if (flags & JackPortIsInput)
       {
         seen_output_ports.insert(name);
         if (this->configuration.output_added)
-          this->configuration.output_added(to_port_info<false>(client, port));
+          this->configuration.output_added(
+              to_port_info<false, libremidi::API::JACK_MIDI>(client, port));
       }
     }
     else
@@ -153,13 +156,15 @@ public:
       if (auto it = seen_input_ports.find(name); it != seen_input_ports.end())
       {
         if (this->configuration.input_removed)
-          this->configuration.input_removed(to_port_info<true>(client, port));
+          this->configuration.input_removed(
+              to_port_info<true, libremidi::API::JACK_MIDI>(client, port));
         seen_input_ports.erase(it);
       }
       if (auto it = seen_output_ports.find(name); it != seen_output_ports.end())
       {
         if (this->configuration.output_removed)
-          this->configuration.output_removed(to_port_info<false>(client, port));
+          this->configuration.output_removed(
+              to_port_info<false, libremidi::API::JACK_MIDI>(client, port));
         seen_output_ports.erase(it);
       }
     }
@@ -172,16 +177,13 @@ public:
     if (!configuration.has_callbacks())
       return;
 
-    jack_set_port_registration_callback(
+    jack_set_port_registration_callback(this->client, +[](jack_port_id_t p, int r, void* arg) {
-        this->client,
-        +[](jack_port_id_t p, int r, void* arg) {
       auto& self = *(observer_jack*)arg;
       if (auto port = jack_port_by_id(self.client, p))
       {
         self.on_port_callback(port, r != 0);
       }
-        },
+    }, this);
-        this);
 
     jack_set_port_rename_callback(
         this->client,
@@ -191,20 +193,21 @@ public:
       auto port = jack_port_by_id(self.client, p);
       if (!port)
         return;
-        },
+    }, this);
-        this);
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_MIDI; }
 
   std::vector<libremidi::input_port> get_input_ports() const noexcept override
   {
-    return get_ports<true>(this->client, nullptr, JackPortIsOutput);
+    return get_ports<true, libremidi::API::JACK_MIDI>(
+        this->client, nullptr, port_type, JackPortIsOutput, false);
   }
 
   std::vector<libremidi::output_port> get_output_ports() const noexcept override
   {
-    return get_ports<false>(this->client, nullptr, JackPortIsInput);
+    return get_ports<false, libremidi::API::JACK_MIDI>(
+        this->client, nullptr, port_type, JackPortIsInput, false);
   }
 
   ~observer_jack()

include/libremidi/backends/jack/shared_handler.hpp

@@ -8,7 +8,7 @@
 
   #include <variant>
 
-namespace libremidi::jack
+NAMESPACE_LIBREMIDI::jack
 {
 
 // Create a JACK client which will be shared across objects
@@ -23,13 +23,10 @@ struct shared_handler : public libremidi::shared_context
     client = jack_client_open(v.data(), JackNoStartServer, &status);
     assert(client);
     assert(status == 0);
-    jack_set_process_callback(
+    jack_set_process_callback(client, +[](jack_nframes_t cnt, void* ctx) -> int {
-        client,
-        +[](jack_nframes_t cnt, void* ctx) -> int {
       ((shared_handler*)ctx)->jack_callback(cnt);
       return 0;
-        },
+    }, this);
-        this);
   }
 
   virtual void start_processing() override { jack_activate(client); }
@@ -73,11 +70,10 @@ struct shared_handler : public libremidi::shared_context
       switch (ev.type)
       {
         case in_callback_added:
-          midiin_callbacks.push_back(
+          midiin_callbacks.push_back(std::move(*get_if<libremidi::jack_callback>(&ev.payload)));
-              std::move(*std::get_if<libremidi::jack_callback>(&ev.payload)));
           break;
         case in_callback_removed: {
-          auto idx = *std::get_if<int64_t>(&ev.payload);
+          auto idx = *get_if<int64_t>(&ev.payload);
           for (auto it = midiin_callbacks.begin(); it != midiin_callbacks.end();)
           {
             if (it->token == idx)
@@ -93,11 +89,10 @@ struct shared_handler : public libremidi::shared_context
           break;
         }
         case out_callback_added:
-          midiout_callbacks.push_back(
+          midiout_callbacks.push_back(std::move(*get_if<libremidi::jack_callback>(&ev.payload)));
-              std::move(*std::get_if<libremidi::jack_callback>(&ev.payload)));
           break;
         case out_callback_removed:
-          auto idx = *std::get_if<int64_t>(&ev.payload);
+          auto idx = *get_if<int64_t>(&ev.payload);
           for (auto it = midiout_callbacks.begin(); it != midiout_callbacks.end();)
           {
             if (it->token == idx)
@@ -141,7 +136,7 @@ struct shared_handler : public libremidi::shared_context
   struct event
   {
     event_type type;
-    std::variant<libremidi::jack_callback, int64_t> payload;
+    libremidi_variant_alias::variant<libremidi::jack_callback, int64_t> payload;
   };
 
   boost::lockfree::spsc_queue<event> events{16};

include/libremidi/backends/jack_ump.hpp

@@ -0,0 +1,34 @@
+#pragma once
+#include <libremidi/backends/jack_ump/midi_in.hpp>
+#include <libremidi/backends/jack_ump/midi_out.hpp>
+#include <libremidi/backends/jack_ump/observer.hpp>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::jack_ump
+{
+struct backend
+{
+  using midi_in = midi_in_jack;
+  using midi_out = midi_out_jack;
+  using midi_observer = observer_jack;
+  using midi_in_configuration = jack_ump::input_configuration;
+  using midi_out_configuration = jack_ump::output_configuration;
+  using midi_observer_configuration = jack_ump::observer_configuration;
+  static const constexpr auto API = libremidi::API::JACK_UMP;
+  static const constexpr std::string_view name = "jack_ump";
+  static const constexpr std::string_view display_name = "JACK (UMP)";
+
+  static inline bool available() noexcept
+  {
+#if LIBREMIDI_WEAKJACK
+    if (WeakJack::instance().available() != 0)
+      return false;
+#endif
+
+    int major, minor, micro, patch;
+    jack_get_version(&major, &minor, &micro, &patch);
+    return (major >= 3 && minor >= 1 && micro >= 4);
+  }
+};
+}

include/libremidi/backends/jack_ump/config.hpp

@@ -0,0 +1,33 @@
+#pragma once
+#include <libremidi/backends/jack/config.hpp>
+
+NAMESPACE_LIBREMIDI::jack_ump
+{
+struct input_configuration
+{
+  std::string client_name = "libremidi client";
+
+  jack_client_t* context{};
+  std::function<void(libremidi::jack_callback)> set_process_func{};
+  std::function<void(int64_t)> clear_process_func{};
+};
+
+struct output_configuration
+{
+  std::string client_name = "libremidi client";
+
+  jack_client_t* context{};
+  std::function<void(libremidi::jack_callback)> set_process_func{};
+  std::function<void(int64_t)> clear_process_func{};
+
+  int32_t ringbuffer_size = 16384;
+  bool direct = false;
+};
+
+struct observer_configuration
+{
+  std::string client_name = "libremidi client";
+  jack_client_t* context{};
+};
+
+}

include/libremidi/backends/jack_ump/midi_in.hpp

@@ -0,0 +1,119 @@
+#pragma once
+#include <libremidi/backends/jack/helpers.hpp>
+#include <libremidi/backends/jack_ump/config.hpp>
+#include <libremidi/detail/midi_in.hpp>
+#include <libremidi/detail/midi_stream_decoder.hpp>
+
+NAMESPACE_LIBREMIDI::jack_ump
+{
+class midi_in_jack final
+    : public midi2::in_api
+    , public jack_helpers
+    , private jack_midi1
+    , public error_handler
+{
+public:
+  using midi_api::client_open_;
+  struct
+      : libremidi::ump_input_configuration
+      , jack_ump::input_configuration
+  {
+  } configuration;
+
+  explicit midi_in_jack(
+      libremidi::ump_input_configuration&& conf, jack_ump::input_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+    auto status = connect(*this);
+    if (!this->client)
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
+
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_in_jack() override
+  {
+    midi_in_jack::close_port();
+
+    disconnect(*this);
+  }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_UMP; }
+
+  stdx::error open_port(const input_port& port, std::string_view portName) override
+  {
+    if (auto err
+        = create_local_port(*this, portName, port_type, JackPortFlags(JackPortIsInput | 0x20));
+        err != stdx::error{})
+      return err;
+
+    if (int err = jack_connect(this->client, port.port_name.c_str(), jack_port_name(this->port));
+        err != 0 && err != EEXIST)
+    {
+      libremidi_handle_error(
+          configuration,
+          "could not connect to port: " + port.port_name + " -> " + jack_port_name(this->port));
+      return from_errc(err);
+    }
+    return stdx::error{};
+  }
+
+  stdx::error open_virtual_port(std::string_view portName) override
+  {
+    return create_local_port(*this, portName, port_type, JackPortFlags(JackPortIsInput | 0x20));
+  }
+
+  stdx::error close_port() override { return do_close_port(); }
+
+  stdx::error set_port_name(std::string_view portName) override
+  {
+    int ret = jack_port_rename(this->client, this->port, portName.data());
+    return from_errc(ret);
+  }
+
+  timestamp absolute_timestamp() const noexcept override
+  {
+    return 1000 * jack_frames_to_time(client, jack_frame_time(client));
+  }
+
+  int process(jack_nframes_t nframes)
+  {
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = true,
+        .absolute_is_monotonic = true,
+        .has_samples = true,
+    };
+    void* buff = jack_port_get_buffer(this->port, nframes);
+
+    // Timing
+    jack_nframes_t current_frames{};
+    jack_time_t current_usecs{}; // roughly CLOCK_MONOTONIC
+    jack_time_t next_usecs{};
+    float period_usecs{};
+    jack_get_cycle_times(
+        this->client, &current_frames, &current_usecs, &next_usecs, &period_usecs);
+
+    // We have midi events in buffer
+    uint32_t ev_count = jack_midi_get_event_count(buff);
+    for (uint32_t j = 0; j < ev_count; j++)
+    {
+      jack_midi_event_t event{};
+      jack_midi_event_get(&event, buff, j);
+      const auto to_ns
+          = [=, this] { return 1000 * jack_frames_to_time(client, current_frames + event.time); };
+
+      m_processing.on_bytes(
+          {(uint32_t*)event.buffer, (uint32_t*)(event.buffer + event.size)},
+          m_processing.timestamp<timestamp_info>(to_ns, event.time));
+    }
+
+    return 0;
+  }
+
+  midi2::input_state_machine m_processing{this->configuration};
+};
+}

include/libremidi/backends/jack_ump/midi_out.hpp

@@ -0,0 +1,184 @@
+#pragma once
+#include <libremidi/backends/jack/helpers.hpp>
+#include <libremidi/backends/jack_ump/config.hpp>
+#include <libremidi/detail/midi_out.hpp>
+
+NAMESPACE_LIBREMIDI::jack_ump
+{
+class midi_out_jack
+    : public midi2::out_api
+    , public jack_helpers
+    , private jack_midi1
+    , public error_handler
+{
+public:
+  using midi_api::client_open_;
+  struct
+      : libremidi::output_configuration
+      , jack_ump::output_configuration
+  {
+  } configuration;
+
+  midi_out_jack(libremidi::output_configuration&& conf, jack_ump::output_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+  }
+
+  ~midi_out_jack() override { }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_UMP; }
+
+  stdx::error open_port(const output_port& port, std::string_view portName) override
+  {
+    if (auto err
+        = create_local_port(*this, portName, port_type, JackPortFlags(JackPortIsOutput | 0x20));
+        err != stdx::error{})
+      return err;
+
+    // Connecting to the output
+    if (int err = jack_connect(this->client, jack_port_name(this->port), port.port_name.c_str());
+        err != 0 && err != EEXIST)
+    {
+      libremidi_handle_error(configuration, "could not connect to port" + port.port_name);
+      return from_errc(err);
+    }
+
+    return stdx::error{};
+  }
+
+  stdx::error open_virtual_port(std::string_view portName) override
+  {
+    return create_local_port(*this, portName, port_type, JackPortFlags(JackPortIsOutput | 0x20));
+  }
+
+  stdx::error close_port() override { return do_close_port(); }
+
+  stdx::error set_port_name(std::string_view portName) override
+  {
+    int ret = jack_port_rename(this->client, this->port, portName.data());
+    return from_errc(ret);
+  }
+};
+
+class midi_out_jack_queued final : public midi_out_jack
+{
+public:
+  midi_out_jack_queued(
+      libremidi::output_configuration&& conf, jack_ump::output_configuration&& apiconf)
+      : midi_out_jack{std::move(conf), std::move(apiconf)}
+      , m_queue{configuration.ringbuffer_size}
+  {
+    auto status = connect(*this);
+    if (!this->client)
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
+
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_out_jack_queued() override
+  {
+    midi_out_jack::close_port();
+
+    disconnect(*this);
+  }
+
+  stdx::error send_ump(const uint32_t* message, std::size_t size) override
+  {
+    return m_queue.write((unsigned char*)message, size * sizeof(uint32_t));
+  }
+
+  int process(jack_nframes_t nframes)
+  {
+    void* buff = jack_port_get_buffer(this->port, nframes);
+    jack_midi_clear_buffer(buff);
+
+    this->m_queue.read(buff);
+
+    return 0;
+  }
+
+private:
+  libremidi::jack_queue m_queue;
+};
+
+class midi_out_jack_direct final : public midi_out_jack
+{
+public:
+  midi_out_jack_direct(
+      libremidi::output_configuration&& conf, jack_ump::output_configuration&& apiconf)
+      : midi_out_jack{std::move(conf), std::move(apiconf)}
+  {
+    auto status = connect(*this);
+    if (!this->client)
+    {
+      libremidi_handle_error(configuration, "Could not create JACK client");
+      client_open_ = from_jack_status(status);
+      return;
+    }
+
+    buffer_size = jack_get_buffer_size(this->client);
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_out_jack_direct() override
+  {
+    midi_out_jack::close_port();
+
+    disconnect(*this);
+  }
+
+  int process(jack_nframes_t nframes)
+  {
+    void* buff = jack_port_get_buffer(this->port, nframes);
+    jack_midi_clear_buffer(buff);
+    return 0;
+  }
+
+  stdx::error send_ump(const uint32_t* message, std::size_t size) override
+  {
+    void* buff = jack_port_get_buffer(this->port, buffer_size);
+    int ret = jack_midi_event_write(buff, 0, (unsigned char*)message, size * sizeof(uint32_t));
+    return from_errc(ret);
+  }
+
+  int convert_timestamp(int64_t user) const noexcept
+  {
+    switch (configuration.timestamps)
+    {
+      case timestamp_mode::AudioFrame:
+        return static_cast<int>(user);
+
+      default:
+        // TODO
+        return 0;
+    }
+  }
+
+  stdx::error schedule_ump(int64_t ts, const uint32_t* message, size_t size) override
+  {
+    void* buff = jack_port_get_buffer(this->port, buffer_size);
+    int ret = jack_midi_event_write(
+        buff, convert_timestamp(ts), (unsigned char*)message, size * sizeof(uint32_t));
+    return from_errc(ret);
+  }
+
+  int buffer_size{};
+};
+}
+
+NAMESPACE_LIBREMIDI
+{
+template <>
+inline std::unique_ptr<midi_out_api>
+make<jack_ump::midi_out_jack>(output_configuration&& conf, jack_ump::output_configuration&& api)
+{
+  if (api.direct)
+    return std::make_unique<jack_ump::midi_out_jack_direct>(std::move(conf), std::move(api));
+  else
+    return std::make_unique<jack_ump::midi_out_jack_queued>(std::move(conf), std::move(api));
+}
+}

include/libremidi/backends/jack_ump/observer.hpp

@@ -0,0 +1,243 @@
+#pragma once
+#include <libremidi/backends/jack/helpers.hpp>
+#include <libremidi/backends/jack_ump/config.hpp>
+#include <libremidi/detail/observer.hpp>
+
+#include <unordered_set>
+
+NAMESPACE_LIBREMIDI::jack_ump
+{
+class observer_jack final
+    : public observer_api
+    , private jack_client
+    , private jack_midi1 // seems like a bug in PipeWire? MIDI 2 flag is set but the MIDI 1 type string is used
+    , private error_handler
+{
+public:
+  struct
+      : libremidi::observer_configuration
+      , jack_ump::observer_configuration
+  {
+  } configuration;
+
+  explicit observer_jack(
+      libremidi::observer_configuration&& conf, jack_ump::observer_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+    // Initialize JACK client
+    if (configuration.context)
+    {
+      this->client = configuration.context;
+      set_callbacks();
+    }
+    else
+    {
+      jack_status_t status{};
+      this->client
+          = jack_client_open(configuration.client_name.c_str(), JackNoStartServer, &status);
+      if (status != jack_status_t{})
+        libremidi_handle_error(configuration, std::to_string((int)status));
+
+      if (this->client != nullptr)
+      {
+        set_callbacks();
+
+        jack_activate(this->client);
+      }
+    }
+  }
+
+  void initial_callback()
+  {
+    {
+      const char** ports = jack_get_ports(client, nullptr, port_type, JackPortIsOutput);
+
+      if (ports != nullptr)
+      {
+        int i = 0;
+        while (ports[i] != nullptr)
+        {
+          const auto port = jack_port_by_name(client, ports[i]);
+          const auto flags = jack_port_flags(port);
+
+          if (!(flags & 0x20)) // midi 2 check
+          {
+            i++;
+            continue;
+          }
+
+          bool physical = flags & JackPortIsPhysical;
+          bool ok = configuration.track_any;
+          if (configuration.track_hardware)
+            ok |= physical;
+          if (configuration.track_virtual)
+            ok |= !physical;
+
+          if (ok)
+          {
+            seen_input_ports.insert(ports[i]);
+            if (this->configuration.input_added && configuration.notify_in_constructor)
+              this->configuration.input_added(
+                  to_port_info<true, libremidi::API::JACK_UMP>(client, port));
+          }
+          i++;
+        }
+      }
+
+      jack_free(ports);
+    }
+
+    {
+      const char** ports = jack_get_ports(client, nullptr, port_type, JackPortIsInput);
+
+      if (ports != nullptr)
+      {
+        int i = 0;
+        while (ports[i] != nullptr)
+        {
+          const auto port = jack_port_by_name(client, ports[i]);
+          const auto flags = jack_port_flags(port);
+
+          if (!(flags & 0x20)) // midi 2 check
+          {
+            i++;
+            continue;
+          }
+
+          bool physical = flags & JackPortIsPhysical;
+          bool ok = configuration.track_any;
+          if (configuration.track_hardware)
+            ok |= physical;
+          if (configuration.track_virtual)
+            ok |= !physical;
+
+          if (ok)
+          {
+            seen_output_ports.insert(ports[i]);
+            if (this->configuration.output_added && configuration.notify_in_constructor)
+              this->configuration.output_added(
+                  to_port_info<false, libremidi::API::JACK_UMP>(client, port));
+          }
+          i++;
+        }
+      }
+
+      jack_free(ports);
+    }
+  }
+
+  void on_port_callback(jack_port_t* port, bool reg)
+  {
+    auto flags = jack_port_flags(port);
+    std::string name = jack_port_name(port);
+    if (reg)
+    {
+      std::string_view type = jack_port_type(port);
+      if (type != port_type)
+        return;
+
+      if (!(flags & 0x20)) // midi 2 check
+        return;
+
+      bool physical = flags & JackPortIsPhysical;
+      bool ok = configuration.track_any;
+      if (configuration.track_hardware)
+        ok |= physical;
+      if (configuration.track_virtual)
+        ok |= !physical;
+      if (!ok)
+        return;
+
+      // Note: we keep track of the ports as
+      // when disconnecting, jack_port_type and jack_port_flags aren't correctly
+      // set anymore.
+
+      if (flags & JackPortIsOutput)
+      {
+        seen_input_ports.insert(name);
+        if (this->configuration.input_added)
+          this->configuration.input_added(
+              to_port_info<true, libremidi::API::JACK_UMP>(client, port));
+      }
+      else if (flags & JackPortIsInput)
+      {
+        seen_output_ports.insert(name);
+        if (this->configuration.output_added)
+          this->configuration.output_added(
+              to_port_info<false, libremidi::API::JACK_UMP>(client, port));
+      }
+    }
+    else
+    {
+      if (auto it = seen_input_ports.find(name); it != seen_input_ports.end())
+      {
+        if (this->configuration.input_removed)
+          this->configuration.input_removed(
+              to_port_info<true, libremidi::API::JACK_UMP>(client, port));
+        seen_input_ports.erase(it);
+      }
+      if (auto it = seen_output_ports.find(name); it != seen_output_ports.end())
+      {
+        if (this->configuration.output_removed)
+          this->configuration.output_removed(
+              to_port_info<false, libremidi::API::JACK_UMP>(client, port));
+        seen_output_ports.erase(it);
+      }
+    }
+  }
+
+  void set_callbacks()
+  {
+    initial_callback();
+
+    if (!configuration.has_callbacks())
+      return;
+
+    jack_set_port_registration_callback(this->client, +[](jack_port_id_t p, int r, void* arg) {
+      auto& self = *(observer_jack*)arg;
+      if (auto port = jack_port_by_id(self.client, p))
+      {
+        self.on_port_callback(port, r != 0);
+      }
+    }, this);
+
+    jack_set_port_rename_callback(
+        this->client,
+        +[](jack_port_id_t p, const char* /*old_name*/, const char* /*new_name*/, void* arg) {
+      const auto& self = *static_cast<observer_jack*>(arg);
+
+      auto port = jack_port_by_id(self.client, p);
+      if (!port)
+        return;
+    }, this);
+  }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::JACK_UMP; }
+
+  std::vector<libremidi::input_port> get_input_ports() const noexcept override
+  {
+    return get_ports<true, libremidi::API::JACK_UMP>(
+        this->client, nullptr, port_type, JackPortIsOutput, true);
+  }
+
+  std::vector<libremidi::output_port> get_output_ports() const noexcept override
+  {
+    return get_ports<false, libremidi::API::JACK_UMP>(
+        this->client, nullptr, port_type, JackPortIsInput, true);
+  }
+
+  ~observer_jack()
+  {
+    if (client && !configuration.context)
+    {
+      // If we own the client, deactivate it
+      jack_deactivate(this->client);
+      jack_client_close(this->client);
+      this->client = nullptr;
+    }
+  }
+
+  std::unordered_set<std::string> seen_input_ports;
+  std::unordered_set<std::string> seen_output_ports;
+};
+}

include/libremidi/backends/kdmapi.hpp

@@ -0,0 +1,43 @@
+#pragma once
+#include <libremidi/backends/kdmapi/midi_in.hpp>
+#include <libremidi/backends/kdmapi/midi_out.hpp>
+#include <libremidi/backends/kdmapi/observer.hpp>
+
+#include <string_view>
+
+//*********************************************************************//
+//  API: OmniMIDI KDMAPI (Keppy's Direct MIDI API)
+//*********************************************************************//
+
+// OmniMIDI is a low-latency MIDI synthesizer driver for Windows.
+// KDMAPI provides a direct interface to OmniMIDI, bypassing the
+// Windows Multimedia API for lower latency.
+//
+// Note: KDMAPI is output-only. The midi_in class is a placeholder
+// that always fails - use a different backend for MIDI input.
+//
+// https://github.com/KeppySoftware/OmniMIDI
+
+namespace libremidi
+{
+
+struct kdmapi_backend
+{
+  using midi_in = kdmapi::midi_in;
+  using midi_out = kdmapi::midi_out;
+  using midi_observer = kdmapi::observer;
+  using midi_in_configuration = kdmapi::input_configuration;
+  using midi_out_configuration = kdmapi::output_configuration;
+  using midi_observer_configuration = kdmapi::observer_configuration;
+  static const constexpr auto API = libremidi::API::KDMAPI;
+  static const constexpr std::string_view name = "kdmapi";
+  static const constexpr std::string_view display_name = "OmniMIDI (KDMAPI)";
+
+  static inline bool available() noexcept
+  {
+    return kdmapi::kdmapi_loader::instance().is_available();
+  }
+};
+
+}
+

include/libremidi/backends/kdmapi/config.hpp

@@ -0,0 +1,23 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+namespace libremidi::kdmapi
+{
+// KDMAPI does not support MIDI input
+struct input_configuration
+{
+};
+
+struct output_configuration
+{
+  // Use the no-buffer variant of SendDirectData for lowest latency
+  // This bypasses OmniMIDI's internal buffer
+  bool use_no_buffer = false;
+};
+
+struct observer_configuration
+{
+};
+
+}
+

include/libremidi/backends/kdmapi/helpers.hpp

@@ -0,0 +1,178 @@
+#pragma once
+// clang-format off
+#define NOMINMAX 1
+#define WIN32_LEAN_AND_MEAN 1
+
+#include <windows.h>
+#include <mmsystem.h>
+// clang-format on
+
+#include <libremidi/detail/midi_api.hpp>
+
+#include <atomic>
+#include <mutex>
+
+namespace libremidi::kdmapi
+{
+
+using IsKDMAPIAvailable_t = BOOL(WINAPI*)();
+using InitializeKDMAPIStream_t = BOOL(WINAPI*)();
+using TerminateKDMAPIStream_t = BOOL(WINAPI*)();
+using ResetKDMAPIStream_t = VOID(WINAPI*)();
+using SendDirectData_t = VOID(WINAPI*)(DWORD);
+using SendDirectDataNoBuf_t = VOID(WINAPI*)(DWORD);
+using SendDirectLongData_t = UINT(WINAPI*)(MIDIHDR*, UINT);
+using SendDirectLongDataNoBuf_t = UINT(WINAPI*)(LPSTR, DWORD);
+using PrepareLongData_t = UINT(WINAPI*)(MIDIHDR*, UINT);
+using UnprepareLongData_t = UINT(WINAPI*)(MIDIHDR*, UINT);
+using ReturnKDMAPIVer_t = BOOL(WINAPI*)(LPDWORD, LPDWORD, LPDWORD, LPDWORD);
+
+class kdmapi_loader
+{
+public:
+  static kdmapi_loader& instance()
+  {
+    static kdmapi_loader loader;
+    return loader;
+  }
+
+  bool is_available() const noexcept { return m_available; }
+
+  HMODULE handle() const noexcept { return m_handle; }
+
+  // KDMAPI function pointers
+  IsKDMAPIAvailable_t IsKDMAPIAvailable{};
+  InitializeKDMAPIStream_t InitializeKDMAPIStream{};
+  TerminateKDMAPIStream_t TerminateKDMAPIStream{};
+  ResetKDMAPIStream_t ResetKDMAPIStream{};
+  SendDirectData_t SendDirectData{};
+  SendDirectDataNoBuf_t SendDirectDataNoBuf{};
+  SendDirectLongData_t SendDirectLongData{};
+  SendDirectLongDataNoBuf_t SendDirectLongDataNoBuf{};
+  PrepareLongData_t PrepareLongData{};
+  UnprepareLongData_t UnprepareLongData{};
+  ReturnKDMAPIVer_t ReturnKDMAPIVer{};
+
+private:
+  kdmapi_loader()
+  {
+    // Try to get OmniMIDI if it's already loaded
+    m_handle = GetModuleHandleW(L"OmniMIDI");
+    if (!m_handle)
+    {
+      // Try to load it explicitly
+      m_handle = LoadLibraryW(L"OmniMIDI.dll");
+    }
+
+    if (!m_handle)
+    {
+      m_available = false;
+      return;
+    }
+
+#if !defined(_MSC_VER)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-function-type"
+#endif
+
+    // Load all function pointers
+    IsKDMAPIAvailable
+        = reinterpret_cast<IsKDMAPIAvailable_t>(GetProcAddress(m_handle, "IsKDMAPIAvailable"));
+    InitializeKDMAPIStream = reinterpret_cast<InitializeKDMAPIStream_t>(
+        GetProcAddress(m_handle, "InitializeKDMAPIStream"));
+    TerminateKDMAPIStream = reinterpret_cast<TerminateKDMAPIStream_t>(
+        GetProcAddress(m_handle, "TerminateKDMAPIStream"));
+    ResetKDMAPIStream
+        = reinterpret_cast<ResetKDMAPIStream_t>(GetProcAddress(m_handle, "ResetKDMAPIStream"));
+    SendDirectData
+        = reinterpret_cast<SendDirectData_t>(GetProcAddress(m_handle, "SendDirectData"));
+    SendDirectDataNoBuf
+        = reinterpret_cast<SendDirectDataNoBuf_t>(GetProcAddress(m_handle, "SendDirectDataNoBuf"));
+    SendDirectLongData
+        = reinterpret_cast<SendDirectLongData_t>(GetProcAddress(m_handle, "SendDirectLongData"));
+    SendDirectLongDataNoBuf = reinterpret_cast<SendDirectLongDataNoBuf_t>(
+        GetProcAddress(m_handle, "SendDirectLongDataNoBuf"));
+    PrepareLongData
+        = reinterpret_cast<PrepareLongData_t>(GetProcAddress(m_handle, "PrepareLongData"));
+    UnprepareLongData
+        = reinterpret_cast<UnprepareLongData_t>(GetProcAddress(m_handle, "UnprepareLongData"));
+    ReturnKDMAPIVer
+        = reinterpret_cast<ReturnKDMAPIVer_t>(GetProcAddress(m_handle, "ReturnKDMAPIVer"));
+
+#if !defined(_MSC_VER)
+#pragma GCC diagnostic pop
+#endif
+
+    // Check if the minimum required functions are available
+    if (!IsKDMAPIAvailable || !InitializeKDMAPIStream || !TerminateKDMAPIStream || !SendDirectData)
+    {
+      m_available = false;
+      return;
+    }
+
+    // Call IsKDMAPIAvailable to activate KDMAPI mode in OmniMIDI
+    m_available = IsKDMAPIAvailable() != FALSE;
+  }
+
+  ~kdmapi_loader()
+  {
+  }
+
+  kdmapi_loader(const kdmapi_loader&) = delete;
+  kdmapi_loader& operator=(const kdmapi_loader&) = delete;
+
+  HMODULE m_handle{};
+  bool m_available{false};
+};
+
+class kdmapi_stream_manager
+{
+public:
+  static kdmapi_stream_manager& instance()
+  {
+    static kdmapi_stream_manager mgr;
+    return mgr;
+  }
+
+  bool acquire()
+  {
+    std::lock_guard lock{m_mutex};
+    auto& loader = kdmapi_loader::instance();
+    if (!loader.is_available())
+      return false;
+
+    if (m_rc == 0)
+    {
+      if (!loader.InitializeKDMAPIStream())
+        return false;
+    }
+    ++m_rc;
+    return true;
+  }
+
+  void release()
+  {
+    std::lock_guard lock{m_mutex};
+    if (m_rc == 0)
+      return;
+
+    --m_rc;
+    if (m_rc == 0)
+    {
+      auto& loader = kdmapi_loader::instance();
+      if (loader.TerminateKDMAPIStream)
+        loader.TerminateKDMAPIStream();
+    }
+  }
+
+private:
+  kdmapi_stream_manager() = default;
+  ~kdmapi_stream_manager() = default;
+  kdmapi_stream_manager(const kdmapi_stream_manager&) = delete;
+  kdmapi_stream_manager& operator=(const kdmapi_stream_manager&) = delete;
+
+  std::mutex m_mutex;
+  std::size_t m_rc{0};
+};
+
+}

include/libremidi/backends/kdmapi/midi_in.hpp

@@ -0,0 +1,11 @@
+#pragma once
+#include <libremidi/backends/kdmapi/config.hpp>
+#include <libremidi/backends/dummy.hpp>
+#include <libremidi/detail/midi_in.hpp>
+
+namespace libremidi::kdmapi
+{
+
+using midi_in = libremidi::midi_in_dummy;
+
+}

include/libremidi/backends/kdmapi/midi_out.hpp

@@ -0,0 +1,173 @@
+#pragma once
+#include <libremidi/backends/kdmapi/config.hpp>
+#include <libremidi/backends/kdmapi/helpers.hpp>
+#include <libremidi/backends/kdmapi/observer.hpp>
+#include <libremidi/detail/midi_out.hpp>
+
+namespace libremidi::kdmapi
+{
+
+class midi_out final
+    : public midi1::out_api
+    , public error_handler
+{
+public:
+  struct
+      : libremidi::output_configuration
+      , kdmapi::output_configuration
+  {
+  } configuration;
+
+  midi_out(libremidi::output_configuration&& conf, kdmapi::output_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+    auto& loader = kdmapi_loader::instance();
+    if (!loader.is_available())
+    {
+      libremidi_handle_error(
+          configuration, "KDMAPI is not available. Is OmniMIDI installed?");
+      this->client_open_ = std::errc::no_such_device;
+      return;
+    }
+
+    this->client_open_ = stdx::error{};
+  }
+
+  ~midi_out() override
+  {
+    midi_out::close_port();
+    this->client_open_ = std::errc::not_connected;
+  }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::KDMAPI; }
+
+  stdx::error open_port(const output_port& port, std::string_view) override
+  {
+    if (port.api != libremidi::API::KDMAPI)
+    {
+      libremidi_handle_error(configuration, "port is not a KDMAPI port");
+      return std::errc::invalid_argument;
+    }
+
+    return do_open();
+  }
+
+  stdx::error do_open()
+  {
+    auto& mgr = kdmapi_stream_manager::instance();
+    if (!mgr.acquire())
+    {
+      libremidi_handle_error(configuration, "failed to initialize KDMAPI stream");
+      return std::errc::io_error;
+    }
+
+    connected_ = true;
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override
+  {
+    if (connected_)
+    {
+      auto& mgr = kdmapi_stream_manager::instance();
+      mgr.release();
+      connected_ = false;
+    }
+    return stdx::error{};
+  }
+
+  stdx::error send_message(const unsigned char* message, size_t size) override
+  {
+    if (!connected_)
+      return std::errc::not_connected;
+
+    if (size == 0)
+    {
+      libremidi_handle_warning(configuration, "message argument is empty!");
+      return std::errc::invalid_argument;
+    }
+
+    auto& loader = kdmapi_loader::instance();
+
+    if (message[0] == 0xF0)
+    {
+      // SysEx message
+      return send_sysex(message, size);
+    }
+    else
+    {
+      // Channel or system message
+      if (size > 3)
+      {
+        libremidi_handle_warning(
+            configuration, "message size is greater than 3 bytes (and not sysex)!");
+        return std::errc::message_size;
+      }
+
+      // Pack MIDI bytes into DWORD
+      DWORD packet = 0;
+      std::copy_n(message, size, reinterpret_cast<unsigned char*>(&packet));
+
+      // Send the message
+      if (configuration.use_no_buffer && loader.SendDirectDataNoBuf)
+        loader.SendDirectDataNoBuf(packet);
+      else
+        loader.SendDirectData(packet);
+    }
+
+    return stdx::error{};
+  }
+
+private:
+  stdx::error send_sysex(const unsigned char* message, size_t size)
+  {
+    auto& loader = kdmapi_loader::instance();
+
+    if (configuration.use_no_buffer && loader.SendDirectLongDataNoBuf)
+    {
+      // Use the no-buffer variant - it takes raw data directly
+      loader.SendDirectLongDataNoBuf(
+          const_cast<LPSTR>(reinterpret_cast<const char*>(message)), static_cast<DWORD>(size));
+      return stdx::error{};
+    }
+
+    // Standard path with MIDIHDR
+    buffer_.assign(message, message + size);
+
+    MIDIHDR sysex{};
+    sysex.lpData = reinterpret_cast<LPSTR>(buffer_.data());
+    sysex.dwBufferLength = static_cast<DWORD>(size);
+    sysex.dwFlags = 0;
+
+    if (loader.PrepareLongData)
+    {
+      UINT result = loader.PrepareLongData(&sysex, sizeof(MIDIHDR));
+      if (result != MMSYSERR_NOERROR)
+      {
+        libremidi_handle_error(configuration, "error preparing sysex header");
+        return std::errc::io_error;
+      }
+    }
+
+    if (loader.SendDirectLongData)
+    {
+      UINT result = loader.SendDirectLongData(&sysex, sizeof(MIDIHDR));
+      if (result != MMSYSERR_NOERROR)
+      {
+        libremidi_handle_error(configuration, "error sending sysex message");
+        // Still try to unprepare
+      }
+    }
+
+    if (loader.UnprepareLongData)
+    {
+      loader.UnprepareLongData(&sysex, sizeof(MIDIHDR));
+    }
+
+    return stdx::error{};
+  }
+
+  std::vector<char> buffer_;
+};
+
+}

include/libremidi/backends/kdmapi/observer.hpp

@@ -0,0 +1,86 @@
+#pragma once
+#include <libremidi/backends/kdmapi/config.hpp>
+#include <libremidi/backends/kdmapi/helpers.hpp>
+#include <libremidi/detail/observer.hpp>
+
+namespace libremidi::kdmapi
+{
+
+class observer final : public observer_api
+{
+public:
+  struct
+      : libremidi::observer_configuration
+      , kdmapi::observer_configuration
+  {
+  } configuration;
+
+  explicit observer(
+      libremidi::observer_configuration&& conf, kdmapi::observer_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+    if (!configuration.has_callbacks())
+      return;
+
+    auto& loader = kdmapi_loader::instance();
+    if (!loader.is_available())
+      return;
+
+    // KDMAPI provides a single virtual output port
+    if (configuration.notify_in_constructor)
+    {
+      if (configuration.output_added)
+      {
+        auto ports = get_output_ports();
+        for (const auto& port : ports)
+          configuration.output_added(port);
+      }
+    }
+  }
+
+  ~observer() = default;
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::KDMAPI; }
+
+  std::vector<libremidi::input_port> get_input_ports() const noexcept override
+  {
+    // KDMAPI does not provide input ports
+    return {};
+  }
+
+  std::vector<libremidi::output_port> get_output_ports() const noexcept override
+  {
+    auto& loader = kdmapi_loader::instance();
+    if (!loader.is_available())
+      return {};
+
+    // Get KDMAPI version for display name
+    std::string display_name = "OmniMIDI";
+    if (loader.ReturnKDMAPIVer)
+    {
+      DWORD major{}, minor{}, build{}, rev{};
+      if (loader.ReturnKDMAPIVer(&major, &minor, &build, &rev))
+      {
+        display_name += " (KDMAPI ";
+        display_name += std::to_string(major);
+        display_name += ".";
+        display_name += std::to_string(minor);
+        display_name += ".";
+        display_name += std::to_string(build);
+        display_name += ")";
+      }
+    }
+
+    return {libremidi::output_port{
+        {.api = libremidi::API::KDMAPI,
+         .client = 0,
+         .port = 0,
+         .manufacturer = "KeppySoftware",
+         .device_name = "OmniMIDI",
+         .port_name = "OmniMIDI",
+         .display_name = std::move(display_name)},
+    }};
+  }
+};
+
+}

include/libremidi/backends/keyboard.hpp

@@ -0,0 +1,23 @@
+#pragma once
+#include <libremidi/backends/dummy.hpp>
+#include <libremidi/backends/keyboard/midi_in.hpp>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI
+{
+struct kbd_backend
+{
+  using midi_in = midi_in_kbd;
+  using midi_in_configuration = kbd_input_configuration;
+  using midi_out = midi_out_dummy;
+  using midi_observer = observer_dummy;
+  using midi_out_configuration = dummy_configuration;
+  using midi_observer_configuration = dummy_configuration;
+  static const constexpr auto API = libremidi::API::KEYBOARD;
+  static const constexpr std::string_view name = "keyboard";
+  static const constexpr std::string_view display_name = "Computer keyboard";
+
+  static inline bool available() noexcept { return true; }
+};
+}

include/libremidi/backends/keyboard/config.hpp

@@ -0,0 +1,154 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+#include <functional>
+#include <map>
+
+NAMESPACE_LIBREMIDI
+{
+enum kbd_event
+{
+  NOTE_0 = 0x0,         // C
+  VEL_0 = NOTE_0 + 128, // Set velocity to 0
+  OCT_0 = VEL_0 + 128,  // Set octave to 0
+  OCTAVE_PLUS = OCT_0 + 128,
+  OCTAVE_MINUS,
+  VELOCITY_PLUS,
+  VELOCITY_MINUS,
+};
+
+// Default map
+//
+// ,---,---,---,---,---,---,---,---,---,---,---,---,---,-------,
+// | V0| V1| V2| V3| V4| V5| V6| V7| V8| V9|V10|V11|V12| <-    |
+// |---'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-----|
+// | ->| |   | C#| D#|   | F#| G#| A#|   | C#| D#|   | F#|     |
+// |-----',--',--',--',--',--',--',--',--',--',--',--',--'|    |
+// | Caps | C | D | E | F | G | A | B | C | D | E | F | G |    |
+// |----,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'-,-'---'----|
+// | -^ |   | O-| O+| V-| V+|   |   |   |   |   |   |   ----^  |
+// |----'-,-',--'--,'---'---'---'---'---'---'-,-'---',--,------|
+// | ctrl |  | alt |                          |altgr |  | ctrl |
+// '------'  '-----'--------------------------'------'  '------'
+
+// clang-format off
+
+// actually based on macOS virtual codes as it seems
+// impossible to get raw scan codes.
+// https://eastmanreference.com/complete-list-of-applescript-key-codes
+LIBREMIDI_STATIC const std::map<int, int>& scancode_map_macos(){
+  static const std::map<int, int> ret{
+  {  0, NOTE_0}, // C0
+  { 13, NOTE_0 + 1},
+  {  1, NOTE_0 + 2},
+  { 14, NOTE_0 + 3},
+  {  2, NOTE_0 + 4},
+  {  3, NOTE_0 + 5},
+  { 17, NOTE_0 + 6},
+  {  5, NOTE_0 + 7},
+  { 16, NOTE_0 + 8},
+  {  4, NOTE_0 + 9},
+  { 32, NOTE_0 + 10},
+  { 38, NOTE_0 + 11},
+  { 40, NOTE_0 + 12}, // C1
+  { 31, NOTE_0 + 13},
+  { 37, NOTE_0 + 14},
+  { 35, NOTE_0 + 15},
+  { 41, NOTE_0 + 16},
+  { 39, NOTE_0 + 17},
+  { 30, NOTE_0 + 18},
+  { 42, NOTE_0 + 19},
+
+  { 50, VEL_0 + int(0)},
+  { 18, VEL_0 + int(1 * 127 / 12)},
+  { 19, VEL_0 + int(2 * 127 / 12)},
+  { 20, VEL_0 + int(3 * 127 / 12)},
+  { 21, VEL_0 + int(4 * 127 / 12)},
+  { 23, VEL_0 + int(5 * 127 / 12)},
+  { 22, VEL_0 + int(6 * 127 / 12)},
+  { 26, VEL_0 + int(7 * 127 / 12)},
+  { 28, VEL_0 + int(8 * 127 / 12)},
+  { 25, VEL_0 + int(9 * 127 / 12)},
+  { 29, VEL_0 + int(10 * 127 / 12)},
+  { 27, VEL_0 + int(11 * 127 / 12)},
+  { 24, VEL_0 + int(127)},
+
+  { 6, OCTAVE_MINUS },
+  { 7, OCTAVE_PLUS },
+  { 8, VELOCITY_MINUS },
+  { 9, VELOCITY_PLUS},
+  };
+  return ret;
+}
+
+// Use: https://kbdlayout.info/KBDUSX/scancodes
+// Also valid for windows
+LIBREMIDI_STATIC const std::map<int, int>& scancode_map_linux() {
+  static const std::map<int, int> ret{
+  { 0x1E, NOTE_0}, // C0
+  { 0x11, NOTE_0 + 1},
+  { 0x1F, NOTE_0 + 2},
+  { 0x12, NOTE_0 + 3},
+  { 0x20, NOTE_0 + 4},
+  { 0x21, NOTE_0 + 5},
+  { 0x14, NOTE_0 + 6},
+  { 0x22, NOTE_0 + 7},
+  { 0x15, NOTE_0 + 8},
+  { 0x23, NOTE_0 + 9},
+  { 0x16, NOTE_0 + 10},
+  { 0x24, NOTE_0 + 11},
+  { 0x25, NOTE_0 + 12}, // C1
+  { 0x18, NOTE_0 + 13},
+  { 0x26, NOTE_0 + 14},
+  { 0x19, NOTE_0 + 15},
+  { 0x27, NOTE_0 + 16},
+  { 0x28, NOTE_0 + 17},
+  { 0x1B, NOTE_0 + 18},
+  { 0x2B, NOTE_0 + 19},
+
+  { 0x29, VEL_0 + int(0)},
+  { 0x02, VEL_0 + int(1 * 127 / 12)},
+  { 0x03, VEL_0 + int(2 * 127 / 12)},
+  { 0x04, VEL_0 + int(3 * 127 / 12)},
+  { 0x05, VEL_0 + int(4 * 127 / 12)},
+  { 0x06, VEL_0 + int(5 * 127 / 12)},
+  { 0x07, VEL_0 + int(6 * 127 / 12)},
+  { 0x08, VEL_0 + int(7 * 127 / 12)},
+  { 0x09, VEL_0 + int(8 * 127 / 12)},
+  { 0x0A, VEL_0 + int(9 * 127 / 12)},
+  { 0x0B, VEL_0 + int(10 * 127 / 12)},
+  { 0x0C, VEL_0 + int(11 * 127 / 12)},
+  { 0x0D, VEL_0 + int(127)},
+
+  { 0x2C, OCTAVE_MINUS },
+  { 0x2D, OCTAVE_PLUS },
+  { 0x2E, VELOCITY_MINUS },
+  { 0x2F, VELOCITY_PLUS},
+  };
+  return ret;
+}
+// clang-format on
+/**
+ * Used to set up keyboard input.
+ * Your app should pass a function that will give you a callback
+ * that you should call whenever you are getting a key input (press or release).
+ */
+struct kbd_input_configuration
+{
+  // Note that on Linux with X11 scancodes should be offset by 8 (an X11 legacy quirk)
+  // ex.: pass QKeyEvent::nativeScanCode() - 8 to this API
+  using scancode_callback = std::function<void(int)>;
+
+  // First argument is on key press, second on key release
+  std::function<void(scancode_callback, scancode_callback)> set_input_scancode_callbacks
+      = [](const scancode_callback&, const scancode_callback&) { };
+
+  std::map<int, int> scancode_map
+#if defined(__APPLE__)
+      = scancode_map_macos()
+#else
+      = scancode_map_linux()
+#endif
+      ;
+};
+}

include/libremidi/backends/keyboard/midi_in.hpp

@@ -0,0 +1,112 @@
+#pragma once
+#include <libremidi/backends/keyboard/config.hpp>
+#include <libremidi/detail/midi_in.hpp>
+
+#include <chrono>
+#include <unordered_map>
+
+NAMESPACE_LIBREMIDI
+{
+class midi_in_kbd final
+    : public midi1::in_api
+    , public error_handler
+{
+public:
+  using midi_api::client_open_;
+  struct
+      : input_configuration
+      , kbd_input_configuration
+  {
+  } configuration;
+
+  explicit midi_in_kbd(input_configuration&& conf, kbd_input_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+  {
+  }
+
+  ~midi_in_kbd() override { }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::KEYBOARD; }
+
+  stdx::error open_port(const input_port&, std::string_view) override
+  {
+    configuration.set_input_scancode_callbacks(
+        [this](int v) { on_keypress(v); }, [this](int v) { on_keyrelease(v); });
+
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override { return stdx::error{}; }
+
+  timestamp absolute_timestamp() const noexcept override
+  {
+    return std::chrono::steady_clock::now().time_since_epoch().count();
+  }
+
+  void on_keypress(int scancode)
+  {
+    using kevent = libremidi::kbd_event;
+
+    auto it = configuration.scancode_map.find(scancode);
+    if (it == configuration.scancode_map.end())
+      return;
+
+    if (it->second >= kevent::NOTE_0 && it->second < (kevent::NOTE_0 + 128))
+    {
+      int note = it->second - kevent::NOTE_0 + 12 * m_current_octave;
+      this->configuration.on_message(
+          libremidi::channel_events::note_on(0, note, m_current_velocity));
+      m_current_notes_scancodes[scancode] = note;
+    }
+    else if (it->second >= kevent::VEL_0 && it->second < (kevent::VEL_0 + 128))
+    {
+      m_current_velocity = it->second - kevent::VEL_0;
+    }
+    else if (it->second >= kevent::OCT_0 && it->second < (kevent::OCT_0 + 128))
+    {
+      m_current_octave = it->second - kevent::OCT_0;
+    }
+    else
+    {
+      switch (it->second)
+      {
+        case kevent::VELOCITY_MINUS:
+          m_current_velocity = std::clamp(m_current_velocity - 10, 0, 127);
+          break;
+        case kevent::VELOCITY_PLUS:
+          m_current_velocity = std::clamp(m_current_velocity + 10, 0, 127);
+          break;
+        case kevent::OCTAVE_MINUS:
+          m_current_octave = std::clamp(m_current_octave - 1, 0, 127);
+          break;
+        case kevent::OCTAVE_PLUS:
+          m_current_octave = std::clamp(m_current_octave + 1, 0, 127);
+          break;
+      }
+    }
+  }
+
+  void on_keyrelease(int scancode)
+  {
+    using kevent = libremidi::kbd_event;
+
+    auto it = configuration.scancode_map.find(scancode);
+    if (it == configuration.scancode_map.end())
+      return;
+
+    if (it->second >= kevent::NOTE_0 && it->second < (kevent::NOTE_0 + 128))
+    {
+      if (auto note_it = m_current_notes_scancodes.find(scancode);
+          note_it != m_current_notes_scancodes.end())
+      {
+        this->configuration.on_message(libremidi::channel_events::note_off(0, note_it->second, 0));
+        m_current_notes_scancodes.erase(note_it);
+      }
+    }
+  }
+
+  int m_current_octave{3};
+  int m_current_velocity{80};
+  std::unordered_map<int, int> m_current_notes_scancodes;
+};
+}

include/libremidi/backends/linux/alsa.hpp

@@ -2,7 +2,7 @@
 
 #include <libremidi/backends/linux/dylib_loader.hpp>
 
-#include <alsa/asoundlib.h>
+#include <alsa/asoundlib.h> // IWYU pragma: export
 
 #if defined(SND_LIB_VERSION)
   #if __has_include(<alsa/rawmidi.h>) && SND_LIB_VERSION >= ((1 << 16) | (2 << 8) | 6)
@@ -13,9 +13,13 @@
   #if __has_include(<alsa/ump.h>) && SND_LIB_VERSION >= ((1 << 16) | (2 << 8) | 10)
     #define LIBREMIDI_ALSA_HAS_UMP 1
   #endif
+
+  #if __has_include(<alsa/ump.h>) && SND_LIB_VERSION >= ((1 << 16) | (2 << 8) | 14)
+    #define LIBREMIDI_ALSA_HAS_UMP_SEQ_EVENTS 1
+  #endif
 #endif
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 struct libasound
@@ -57,13 +61,13 @@ struct libasound
         return;
       }
 
-      LIBREMIDI_SYMBOL_INIT(snd_card, get_name);
+      LIBREMIDI_SYMBOL_INIT(snd_card, get_name)
-      LIBREMIDI_SYMBOL_INIT(snd_card, next);
+      LIBREMIDI_SYMBOL_INIT(snd_card, next)
     }
     bool available{true};
 
-    LIBREMIDI_SYMBOL_DEF(snd_card, get_name);
+    LIBREMIDI_SYMBOL_DEF(snd_card, get_name)
-    LIBREMIDI_SYMBOL_DEF(snd_card, next);
+    LIBREMIDI_SYMBOL_DEF(snd_card, next)
   } card{library};
 
   struct ctl_t
@@ -80,13 +84,13 @@ struct libasound
         return;
       }
 
-      LIBREMIDI_SYMBOL_INIT(snd_ctl, close);
+      LIBREMIDI_SYMBOL_INIT(snd_ctl, close)
-      LIBREMIDI_SYMBOL_INIT(snd_ctl, open);
+      LIBREMIDI_SYMBOL_INIT(snd_ctl, open)
     }
     bool available{true};
 
-    LIBREMIDI_SYMBOL_DEF(snd_ctl, close);
+    LIBREMIDI_SYMBOL_DEF(snd_ctl, close)
-    LIBREMIDI_SYMBOL_DEF(snd_ctl, open);
+    LIBREMIDI_SYMBOL_DEF(snd_ctl, open)
 
     struct rawmidi_t
     {
@@ -98,12 +102,12 @@ struct libasound
           return;
         }
 
-        LIBREMIDI_SYMBOL_INIT(snd_ctl_rawmidi, info);
+        LIBREMIDI_SYMBOL_INIT(snd_ctl_rawmidi, info)
-        LIBREMIDI_SYMBOL_INIT(snd_ctl_rawmidi, next_device);
+        LIBREMIDI_SYMBOL_INIT(snd_ctl_rawmidi, next_device)
       }
       bool available{true};
-      LIBREMIDI_SYMBOL_DEF(snd_ctl_rawmidi, info);
+      LIBREMIDI_SYMBOL_DEF(snd_ctl_rawmidi, info)
-      LIBREMIDI_SYMBOL_DEF(snd_ctl_rawmidi, next_device);
+      LIBREMIDI_SYMBOL_DEF(snd_ctl_rawmidi, next_device)
     } rawmidi;
 
 #if LIBREMIDI_ALSA_HAS_UMP
@@ -117,14 +121,14 @@ struct libasound
           return;
         }
 
-        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, block_info);
+        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, block_info)
-        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, endpoint_info);
+        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, endpoint_info)
-        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, next_device);
+        LIBREMIDI_SYMBOL_INIT(snd_ctl_ump, next_device)
       }
       bool available{true};
-      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, block_info);
+      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, block_info)
-      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, endpoint_info);
+      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, endpoint_info)
-      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, next_device);
+      LIBREMIDI_SYMBOL_DEF(snd_ctl_ump, next_device)
     } ump;
 #endif
   } ctl{library};
@@ -139,23 +143,23 @@ struct libasound
         return;
       }
 
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_decode);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_decode)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_encode);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_encode)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_free);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_free)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_init);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_init)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_new);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_new)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_no_status);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_no_status)
-      LIBREMIDI_SYMBOL_INIT(snd_midi, event_resize_buffer);
+      LIBREMIDI_SYMBOL_INIT(snd_midi, event_resize_buffer)
     }
 
     bool available{true};
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_decode);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_decode)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_encode);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_encode)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_free);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_free)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_init);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_init)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_new);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_new)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_no_status);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_no_status)
-    LIBREMIDI_SYMBOL_DEF(snd_midi, event_resize_buffer);
+    LIBREMIDI_SYMBOL_DEF(snd_midi, event_resize_buffer)
   } midi{library};
 
 #if LIBREMIDI_ALSA_HAS_RAMWIDI
@@ -168,59 +172,59 @@ struct libasound
         available = false;
         return;
       }
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, close);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, close)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_name);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_name)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_subdevice_name);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_subdevice_name)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_subdevices_count);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_get_subdevices_count)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_device);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_device)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_stream);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_stream)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_subdevice);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_set_subdevice)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, info_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, open);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, open)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_current);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_current)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_get_buffer_size);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_get_buffer_size)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_clock_type);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_clock_type)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_no_active_sensing);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_no_active_sensing)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_read_mode);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_set_read_mode)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, params_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors_count);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors_count)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors_revents);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, poll_descriptors_revents)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, read);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, read)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status_get_avail);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status_get_avail)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, status_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, tread);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, tread)
-      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, write);
+      LIBREMIDI_SYMBOL_INIT(snd_rawmidi, write)
     }
 
     bool available{true};
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, close);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, close)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_name);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_name)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_subdevice_name);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_subdevice_name)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_subdevices_count);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_get_subdevices_count)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_device);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_device)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_stream);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_stream)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_subdevice);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_set_subdevice)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, info_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, open);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, open)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_current);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_current)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_get_buffer_size);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_get_buffer_size)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_clock_type);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_clock_type)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_no_active_sensing);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_no_active_sensing)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_read_mode);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_set_read_mode)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, params_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors_count);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors_count)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors_revents);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, poll_descriptors_revents)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, read);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, read)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status_get_avail);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status_get_avail)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, status_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, tread);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, tread)
-    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, write);
+    LIBREMIDI_SYMBOL_DEF(snd_rawmidi, write)
   } rawmidi{library};
 #endif
 
@@ -237,118 +241,134 @@ struct libasound
         return;
       }
 
-      LIBREMIDI_SYMBOL_INIT(snd_seq, alloc_queue);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, alloc_queue)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, client_id);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_id)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_get_client);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_get_client)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_get_name);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_get_name)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_set_client);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_get_card)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_set_client)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, close);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, connect_from);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, close)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, control_queue);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, connect_from)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, create_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, control_queue)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, delete_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, create_port)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, drain_output);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, delete_port)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, event_input);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, drain_output)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, event_input_pending);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, event_input)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, event_output);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, event_input_pending)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, free_event);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, event_output)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, free_queue);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, free_event)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, get_any_client_info);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, free_queue)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, get_any_port_info);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, get_any_client_info)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, get_port_info);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, get_any_port_info)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, open);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, get_port_info)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, poll_descriptors);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, open)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, poll_descriptors_count);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, poll_descriptors)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_addr);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, poll_descriptors_count)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_capability);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_addr)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_name);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_capability)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_name)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_type);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_port)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_capability);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_get_type)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_client);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_capability)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_midi_channels);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_client)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_name);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_midi_channels)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_name)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamping);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_port)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamp_queue);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamping)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamp_real);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamp_queue)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_type);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_timestamp_real)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_set_type)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_free);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_malloc);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_free)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_dest);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_malloc)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_sender);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_time_real);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_dest)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_time_update);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_sender)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, query_next_client);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_time_real)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, query_next_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_time_update)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_set_ppq);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, query_next_client)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_set_tempo);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, query_next_port)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_set_ppq)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, set_client_name);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_set_tempo)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, set_port_info);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, queue_tempo_sizeof)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, set_queue_tempo);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, set_client_name)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, subscribe_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, set_port_info)
-      LIBREMIDI_SYMBOL_INIT(snd_seq, unsubscribe_port);
+      LIBREMIDI_SYMBOL_INIT(snd_seq, set_queue_tempo)
+      LIBREMIDI_SYMBOL_INIT(snd_seq, subscribe_port)
+      LIBREMIDI_SYMBOL_INIT(snd_seq, unsubscribe_port)
+
+#if LIBREMIDI_ALSA_HAS_UMP
+      LIBREMIDI_SYMBOL_INIT(snd_seq, set_client_midi_version)
+      LIBREMIDI_SYMBOL_INIT(snd_seq, get_ump_endpoint_info)
+      LIBREMIDI_SYMBOL_INIT(snd_seq, get_ump_block_info)
+#endif
     }
 
     bool available{true};
-    LIBREMIDI_SYMBOL_DEF(snd_seq, alloc_queue);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, alloc_queue)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, client_id);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_id)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_get_client);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_get_client)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_get_name);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_get_name)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_set_client);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_get_card)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_set_client)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, close);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, connect_from);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, close)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, control_queue);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, connect_from)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, create_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, control_queue)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, delete_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, create_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, drain_output);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, delete_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, event_input);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, drain_output)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, event_input_pending);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, event_input)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, event_output);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, event_input_pending)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, free_event);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, event_output)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, free_queue);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, free_event)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, get_any_client_info);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, free_queue)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, get_any_port_info);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, get_any_client_info)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, get_port_info);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, get_any_port_info)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, open);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, get_port_info)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, poll_descriptors);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, open)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, poll_descriptors_count);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, poll_descriptors)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_addr);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, poll_descriptors_count)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_capability);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_addr)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_name);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_capability)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_name)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_type);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_capability);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_get_type)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_client);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_capability)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_midi_channels);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_client)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_name);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_midi_channels)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_name)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamping);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamp_queue);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamping)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamp_real);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamp_queue)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_type);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_timestamp_real)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_set_type)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_free);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_malloc);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_free)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_dest);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_malloc)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_sender);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_sizeof)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_time_real);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_dest)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_time_update);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_sender)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, query_next_client);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_time_real)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, query_next_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_time_update)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_set_ppq);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, query_next_client)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_set_tempo);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, query_next_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_set_ppq)
+    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_set_tempo)
+    LIBREMIDI_SYMBOL_DEF(snd_seq, queue_tempo_sizeof)
 
-    LIBREMIDI_SYMBOL_DEF(snd_seq, set_client_name);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, set_client_name)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, set_port_info);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, set_port_info)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, set_queue_tempo);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, set_queue_tempo)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, subscribe_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, subscribe_port)
-    LIBREMIDI_SYMBOL_DEF(snd_seq, unsubscribe_port);
+    LIBREMIDI_SYMBOL_DEF(snd_seq, unsubscribe_port)
+
+#if LIBREMIDI_ALSA_HAS_UMP
+    LIBREMIDI_SYMBOL_DEF(snd_seq, set_client_midi_version)
+    LIBREMIDI_SYMBOL_DEF(snd_seq, get_ump_endpoint_info)
+    LIBREMIDI_SYMBOL_DEF(snd_seq, get_ump_block_info)
+#endif
 
 #if LIBREMIDI_ALSA_HAS_UMP
     struct ump_t
@@ -360,18 +380,17 @@ struct libasound
           available = false;
           return;
         }
-        LIBREMIDI_SYMBOL_INIT(snd_seq, set_client_midi_version);
+        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_input)
-        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_input);
+        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_output)
-        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_output);
+        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_output_direct)
-        LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_output_direct);
       }
 
       bool available{true};
 
-      LIBREMIDI_SYMBOL_DEF(snd_seq, set_client_midi_version);
+      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_input)
-      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_input);
+      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_output)
-      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_output);
+      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_output_direct)
-      LIBREMIDI_SYMBOL_DEF(snd_seq_ump, event_output_direct);
+
     } ump;
 #endif
   } seq{library};
@@ -387,39 +406,98 @@ struct libasound
         return;
       }
 
-      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_name);
+      // Core UMP functions
-      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, open)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, close);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, close)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_name);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_sizeof);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, open);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params_current)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, read)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_count);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, tread)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_revents);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, write)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_count)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params_current);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_revents)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, read);
+
-      LIBREMIDI_SYMBOL_INIT(snd_ump, tread);
+      // Endpoint info functions
-      LIBREMIDI_SYMBOL_INIT(snd_ump, write);
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_sizeof)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_card)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_device)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_flags)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_protocol_caps)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_protocol)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_num_blocks)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_version)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_manufacturer_id)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_family_id)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_model_id)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_sw_revision)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_name)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_product_id)
+
+      // Block info functions
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_sizeof)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_set_block_id)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_block_id)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_active)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_flags)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_direction)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_first_group)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_num_groups)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_midi_ci_version)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_sysex8_streams)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_ui_hint)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, block_info_get_name)
     }
 
     bool available{true};
-    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_name);
+
-    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_sizeof);
+    // Core UMP functions
-    LIBREMIDI_SYMBOL_DEF(snd_ump, close);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, open)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_name);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, close)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_sizeof);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, open);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params_current)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_count);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, read)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_revents);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, tread)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, write)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params_current);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_count)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, read);
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_revents)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, tread);
+
-    LIBREMIDI_SYMBOL_DEF(snd_ump, write);
+    // Endpoint info functions
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_sizeof)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_card)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_device)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_flags)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_protocol_caps)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_protocol)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_num_blocks)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_version)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_manufacturer_id)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_family_id)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_model_id)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_sw_revision)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_name)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_get_product_id)
+
+    // Block info functions
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_sizeof)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_set_block_id)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_block_id)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_active)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_flags)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_direction)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_first_group)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_num_groups)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_midi_ci_version)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_sysex8_streams)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_ui_hint)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, block_info_get_name)
   } ump{library};
 #endif
 };
@@ -447,6 +525,8 @@ struct libasound
 #define snd_seq_client_info_alloca(ptr) snd_dylib_alloca(ptr, seq, client_info)
 #undef snd_seq_port_info_alloca
 #define snd_seq_port_info_alloca(ptr) snd_dylib_alloca(ptr, seq, port_info)
+#undef snd_seq_port_subscribe_alloca
+#define snd_seq_port_subscribe_alloca(ptr) snd_dylib_alloca(ptr, seq, port_subscribe)
 #undef snd_seq_queue_tempo_alloca
 #define snd_seq_queue_tempo_alloca(ptr) snd_dylib_alloca(ptr, seq, queue_tempo)
 

include/libremidi/backends/linux/dylib_loader.hpp

@@ -1,10 +1,11 @@
 #pragma once
+#include <libremidi/config.hpp>
 #if __has_include(<dlfcn.h>)
   #include <dlfcn.h>
 
   #include <cassert>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class dylib_loader
 {

include/libremidi/backends/linux/helpers.hpp

@@ -7,7 +7,7 @@
 
 #include <iostream>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct eventfd_notifier
 {

include/libremidi/backends/linux/pipewire.hpp

@@ -4,7 +4,7 @@
 
 #include <pipewire/pipewire.h>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 #pragma GCC diagnostic push
@@ -12,6 +12,8 @@ namespace libremidi
 class libpipewire
 {
 public:
+  decltype(&::pw_get_library_version) get_library_version{};
+
   decltype(&::pw_init) init{};
   decltype(&::pw_deinit) deinit{};
 
@@ -67,12 +69,12 @@ public:
   bool available{true};
 
 private:
-  dylib_loader library;
+  dylib_loader m_library;
 
   libpipewire()
-      : library("libpipewire-0.3.so.0")
+      : m_library("libpipewire-0.3.so.0")
   {
-    if (!library)
+    if (!m_library)
     {
       available = false;
       return;
@@ -81,52 +83,59 @@ private:
     // in terms of regex:
     // decltype\(&::([a-z_]+)\) [a-z_]+{};
     // \1 = library.symbol<decltype(&::\1)>("\1");
-    init = library.symbol<decltype(&::pw_init)>("pw_init");
+    get_library_version
-    deinit = library.symbol<decltype(&::pw_deinit)>("pw_deinit");
+        = m_library.symbol<decltype(&::pw_get_library_version)>("pw_get_library_version");
 
-    context_new = library.symbol<decltype(&::pw_context_new)>("pw_context_new");
+    init = m_library.symbol<decltype(&::pw_init)>("pw_init");
-    context_connect = library.symbol<decltype(&::pw_context_connect)>("pw_context_connect");
+    deinit = m_library.symbol<decltype(&::pw_deinit)>("pw_deinit");
-    context_destroy = library.symbol<decltype(&::pw_context_destroy)>("pw_context_destroy");
 
-    core_disconnect = library.symbol<decltype(&::pw_core_disconnect)>("pw_core_disconnect");
+    context_new = m_library.symbol<decltype(&::pw_context_new)>("pw_context_new");
+    context_connect = m_library.symbol<decltype(&::pw_context_connect)>("pw_context_connect");
+    context_destroy = m_library.symbol<decltype(&::pw_context_destroy)>("pw_context_destroy");
+
+    core_disconnect = m_library.symbol<decltype(&::pw_core_disconnect)>("pw_core_disconnect");
 
     proxy_add_listener
-        = library.symbol<decltype(&::pw_proxy_add_listener)>("pw_proxy_add_listener");
+        = m_library.symbol<decltype(&::pw_proxy_add_listener)>("pw_proxy_add_listener");
-    proxy_destroy = library.symbol<decltype(&::pw_proxy_destroy)>("pw_proxy_destroy");
+    proxy_destroy = m_library.symbol<decltype(&::pw_proxy_destroy)>("pw_proxy_destroy");
 
-    main_loop_new = library.symbol<decltype(&::pw_main_loop_new)>("pw_main_loop_new");
+    main_loop_new = m_library.symbol<decltype(&::pw_main_loop_new)>("pw_main_loop_new");
-    main_loop_destroy = library.symbol<decltype(&::pw_main_loop_destroy)>("pw_main_loop_destroy");
+    main_loop_destroy
-    main_loop_quit = library.symbol<decltype(&::pw_main_loop_quit)>("pw_main_loop_quit");
+        = m_library.symbol<decltype(&::pw_main_loop_destroy)>("pw_main_loop_destroy");
-    main_loop_run = library.symbol<decltype(&::pw_main_loop_run)>("pw_main_loop_run");
+    main_loop_quit = m_library.symbol<decltype(&::pw_main_loop_quit)>("pw_main_loop_quit");
+    main_loop_run = m_library.symbol<decltype(&::pw_main_loop_run)>("pw_main_loop_run");
     main_loop_get_loop
-        = library.symbol<decltype(&::pw_main_loop_get_loop)>("pw_main_loop_get_loop");
+        = m_library.symbol<decltype(&::pw_main_loop_get_loop)>("pw_main_loop_get_loop");
 
-    properties_new = library.symbol<decltype(&::pw_properties_new)>("pw_properties_new");
+    properties_new = m_library.symbol<decltype(&::pw_properties_new)>("pw_properties_new");
-    properties_free = library.symbol<decltype(&::pw_properties_free)>("pw_properties_free");
+    properties_free = m_library.symbol<decltype(&::pw_properties_free)>("pw_properties_free");
-    properties_get = library.symbol<decltype(&::pw_properties_get)>("pw_properties_get");
+    properties_get = m_library.symbol<decltype(&::pw_properties_get)>("pw_properties_get");
 
-    filter_new_simple = library.symbol<decltype(&::pw_filter_new_simple)>("pw_filter_new_simple");
+    filter_new_simple
+        = m_library.symbol<decltype(&::pw_filter_new_simple)>("pw_filter_new_simple");
     filter_get_node_id
-        = library.symbol<decltype(&::pw_filter_get_node_id)>("pw_filter_get_node_id");
+        = m_library.symbol<decltype(&::pw_filter_get_node_id)>("pw_filter_get_node_id");
     filter_get_properties
-        = library.symbol<decltype(&::pw_filter_get_properties)>("pw_filter_get_properties");
+        = m_library.symbol<decltype(&::pw_filter_get_properties)>("pw_filter_get_properties");
-    filter_add_port = library.symbol<decltype(&::pw_filter_add_port)>("pw_filter_add_port");
+    filter_add_port = m_library.symbol<decltype(&::pw_filter_add_port)>("pw_filter_add_port");
     filter_remove_port
-        = library.symbol<decltype(&::pw_filter_remove_port)>("pw_filter_remove_port");
+        = m_library.symbol<decltype(&::pw_filter_remove_port)>("pw_filter_remove_port");
-    filter_update_properties
+    filter_update_properties = m_library.symbol<decltype(&::pw_filter_update_properties)>(
-        = library.symbol<decltype(&::pw_filter_update_properties)>("pw_filter_update_properties");
+        "pw_filter_update_properties");
     filter_update_params
-        = library.symbol<decltype(&::pw_filter_update_params)>("pw_filter_update_params");
+        = m_library.symbol<decltype(&::pw_filter_update_params)>("pw_filter_update_params");
-    filter_get_time = library.symbol<decltype(&::pw_filter_get_time)>("pw_filter_get_time");
+    filter_get_time = m_library.symbol<decltype(&::pw_filter_get_time)>("pw_filter_get_time");
-    filter_destroy = library.symbol<decltype(&::pw_filter_destroy)>("pw_filter_destroy");
+    filter_destroy = m_library.symbol<decltype(&::pw_filter_destroy)>("pw_filter_destroy");
-    filter_connect = library.symbol<decltype(&::pw_filter_connect)>("pw_filter_connect");
+    filter_connect = m_library.symbol<decltype(&::pw_filter_connect)>("pw_filter_connect");
     filter_get_dsp_buffer
-        = library.symbol<decltype(&::pw_filter_get_dsp_buffer)>("pw_filter_get_dsp_buffer");
+        = m_library.symbol<decltype(&::pw_filter_get_dsp_buffer)>("pw_filter_get_dsp_buffer");
     filter_dequeue_buffer
-        = library.symbol<decltype(&::pw_filter_dequeue_buffer)>("pw_filter_dequeue_buffer");
+        = m_library.symbol<decltype(&::pw_filter_dequeue_buffer)>("pw_filter_dequeue_buffer");
     filter_queue_buffer
-        = library.symbol<decltype(&::pw_filter_queue_buffer)>("pw_filter_queue_buffer");
+        = m_library.symbol<decltype(&::pw_filter_queue_buffer)>("pw_filter_queue_buffer");
-    filter_flush = library.symbol<decltype(&::pw_filter_flush)>("pw_filter_flush");
+    filter_flush = m_library.symbol<decltype(&::pw_filter_flush)>("pw_filter_flush");
+
+    assert(get_library_version);
 
     assert(init);
     assert(deinit);

include/libremidi/backends/linux/udev.hpp

@@ -1,12 +1,14 @@
 #pragma once
 #include <libremidi/backends/linux/dylib_loader.hpp>
 #include <libremidi/backends/linux/helpers.hpp>
+#include <libremidi/observer_configuration.hpp>
 
 #include <libudev.h>
 
 #include <cassert>
+#include <optional>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 struct libudev
@@ -23,16 +25,32 @@ struct libudev
       return;
     }
 
-    LIBREMIDI_SYMBOL_INIT(udev, device_get_action);
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_action)
-    LIBREMIDI_SYMBOL_INIT(udev, device_get_subsystem);
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_subsystem)
-    LIBREMIDI_SYMBOL_INIT(udev, device_unref);
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_property_value)
-    LIBREMIDI_SYMBOL_INIT(udev, monitor_enable_receiving);
+    LIBREMIDI_SYMBOL_INIT(udev, device_new_from_syspath)
-    LIBREMIDI_SYMBOL_INIT(udev, monitor_get_fd);
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_parent_with_subsystem_devtype)
-    LIBREMIDI_SYMBOL_INIT(udev, monitor_new_from_netlink);
+    LIBREMIDI_SYMBOL_INIT(udev, device_unref)
-    LIBREMIDI_SYMBOL_INIT(udev, monitor_receive_device);
+
-    LIBREMIDI_SYMBOL_INIT(udev, monitor_unref);
+    LIBREMIDI_SYMBOL_INIT(udev, monitor_enable_receiving)
-    LIBREMIDI_SYMBOL_INIT2(udev, new, create);
+    LIBREMIDI_SYMBOL_INIT(udev, monitor_get_fd)
-    LIBREMIDI_SYMBOL_INIT(udev, unref);
+    LIBREMIDI_SYMBOL_INIT(udev, monitor_new_from_netlink)
+    LIBREMIDI_SYMBOL_INIT(udev, monitor_receive_device)
+    LIBREMIDI_SYMBOL_INIT(udev, monitor_unref)
+
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_new)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_unref)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_add_match_is_initialized)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_add_match_subsystem)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_add_match_sysname)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_scan_devices)
+    LIBREMIDI_SYMBOL_INIT(udev, enumerate_get_list_entry)
+
+    LIBREMIDI_SYMBOL_INIT(udev, list_entry_get_name)
+    LIBREMIDI_SYMBOL_INIT(udev, list_entry_get_next)
+
+    LIBREMIDI_SYMBOL_INIT2(udev, new, create)
+    LIBREMIDI_SYMBOL_INIT(udev, unref)
   }
 
   static const libudev& instance()
@@ -44,16 +62,32 @@ struct libudev
   dylib_loader library;
   bool available{true};
 
-  LIBREMIDI_SYMBOL_DEF(udev, device_get_action);
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_action)
-  LIBREMIDI_SYMBOL_DEF(udev, device_get_subsystem);
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_subsystem)
-  LIBREMIDI_SYMBOL_DEF(udev, device_unref);
+  LIBREMIDI_SYMBOL_DEF(udev, device_new_from_syspath)
-  LIBREMIDI_SYMBOL_DEF(udev, monitor_enable_receiving);
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_property_value)
-  LIBREMIDI_SYMBOL_DEF(udev, monitor_get_fd);
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_parent_with_subsystem_devtype)
-  LIBREMIDI_SYMBOL_DEF(udev, monitor_new_from_netlink);
+  LIBREMIDI_SYMBOL_DEF(udev, device_unref)
-  LIBREMIDI_SYMBOL_DEF(udev, monitor_receive_device);
+
-  LIBREMIDI_SYMBOL_DEF(udev, monitor_unref);
+  LIBREMIDI_SYMBOL_DEF(udev, monitor_enable_receiving)
-  LIBREMIDI_SYMBOL_DEF2(udev, new, create);
+  LIBREMIDI_SYMBOL_DEF(udev, monitor_get_fd)
-  LIBREMIDI_SYMBOL_DEF(udev, unref);
+  LIBREMIDI_SYMBOL_DEF(udev, monitor_new_from_netlink)
+  LIBREMIDI_SYMBOL_DEF(udev, monitor_receive_device)
+  LIBREMIDI_SYMBOL_DEF(udev, monitor_unref)
+
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_new)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_unref)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_add_match_is_initialized)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_add_match_subsystem)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_add_match_sysname)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_scan_devices)
+  LIBREMIDI_SYMBOL_DEF(udev, enumerate_get_list_entry)
+
+  LIBREMIDI_SYMBOL_DEF(udev, list_entry_get_name)
+  LIBREMIDI_SYMBOL_DEF(udev, list_entry_get_next)
+
+  LIBREMIDI_SYMBOL_DEF2(udev, new, create)
+  LIBREMIDI_SYMBOL_DEF(udev, unref)
 };
 
 struct udev_helper
@@ -89,4 +123,107 @@ struct udev_helper
   udev_monitor* monitor{};
 };
 
+struct udev_enumerator
+{
+  explicit udev_enumerator(const udev_helper& h)
+      : helper{h}
+  {
+    auto& udev = helper.udev;
+    auto& instance = helper.instance;
+    enumerator = udev.enumerate_new(instance);
+    assert(enumerator);
+  }
+
+  ~udev_enumerator()
+  {
+    auto& udev = helper.udev;
+    udev.enumerate_unref(enumerator);
+  }
+
+  const udev_helper& helper;
+  udev_enumerate* enumerator{};
+  operator udev_enumerate*() const noexcept { return enumerator; }
+};
+
+struct udev_soundcard_info
+{
+  container_identifier container;
+  device_identifier path;
+  transport_type type{};
+  std::string vendor;
+  std::string product;
+  std::string serial;
+};
+
+inline udev_soundcard_info get_udev_soundcard_info(const udev_helper& helper, int card)
+{
+  auto& udev = helper.udev;
+  udev_enumerator e{helper};
+  udev.enumerate_add_match_subsystem(e, "sound");
+  udev.enumerate_add_match_sysname(e, ("controlC" + std::to_string(card)).c_str());
+  if (udev.enumerate_scan_devices(e) != 0)
+    return {};
+
+  for (auto entry = udev.enumerate_get_list_entry(e); entry;
+       entry = udev.list_entry_get_next(entry))
+  {
+    auto path = udev.list_entry_get_name(entry);
+    if (!path)
+      continue;
+
+    auto dev = udev.device_new_from_syspath(helper.instance, path);
+    if (!dev)
+      continue;
+
+    const auto usb_device
+        = udev.device_get_parent_with_subsystem_devtype(dev, "usb", "usb_device");
+    const auto pci_device = udev.device_get_parent_with_subsystem_devtype(dev, "pci", nullptr);
+
+    transport_type type = transport_type::hardware;
+    if (usb_device)
+      type = (transport_type)(type | transport_type::usb);
+    else if (pci_device)
+      type = (transport_type)(type | transport_type::pci);
+
+    auto id_path = udev.device_get_property_value(dev, "ID_PATH");
+    if (!id_path)
+      id_path = "";
+
+    auto read_property = [&](const char* property) {
+      auto res = udev.device_get_property_value(dev, property);
+      if (!res)
+        res = "";
+      if (strlen(res) == 0)
+      {
+        if (usb_device)
+        {
+          res = udev.device_get_property_value(usb_device, property);
+          if (!res)
+            res = "";
+        }
+        else if (pci_device)
+        {
+          res = udev.device_get_property_value(pci_device, property);
+          if (!res)
+            res = "";
+        }
+      }
+      return res;
+    };
+
+    auto id_vendor = read_property("ID_VENDOR_FROM_DATABASE");
+    auto id_product = read_property("ID_MODEL_FROM_DATABASE");
+    auto id_serial = read_property("ID_SERIAL");
+    auto ret = udev_soundcard_info{
+        .container = id_path,
+        .path = path,
+        .type = type,
+        .vendor = id_vendor,
+        .product = id_product,
+        .serial = id_serial};
+    udev.device_unref(dev);
+    return ret;
+  }
+  return {};
+}
 }

include/libremidi/backends/net/config.hpp

@@ -0,0 +1,89 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+#include <string>
+
+#if !defined(BOOST_ASIO_IO_CONTEXT_HPP)
+namespace boost::asio
+{
+struct io_context;
+}
+#endif
+
+NAMESPACE_LIBREMIDI::net
+{
+enum class protocol
+{
+  OSC_MIDI,
+};
+
+struct dgram_input_configuration
+{
+  std::string client_name = "libremidi client";
+
+  enum protocol protocol = protocol::OSC_MIDI;
+  std::string accept = "0.0.0.0";
+  int port{};
+
+  boost::asio::io_context* io_context{};
+};
+
+struct dgram_output_configuration
+{
+  std::string client_name = "libremidi client";
+
+  enum protocol protocol = protocol::OSC_MIDI;
+  std::string host = "127.0.0.1";
+  int port{};
+  bool broadcast{};
+
+  boost::asio::io_context* io_context{};
+};
+
+struct dgram_observer_configuration
+{
+  std::string client_name = "libremidi client";
+
+  boost::asio::io_context* io_context{};
+};
+
+}
+
+NAMESPACE_LIBREMIDI::net_ump
+{
+enum class protocol
+{
+  OSC_MIDI2,
+};
+
+struct dgram_input_configuration
+{
+  std::string client_name = "libremidi client";
+
+  enum protocol protocol = protocol::OSC_MIDI2;
+  std::string accept = "0.0.0.0";
+  int port{};
+
+  boost::asio::io_context* io_context{};
+};
+
+struct dgram_output_configuration
+{
+  std::string client_name = "libremidi client";
+
+  enum protocol protocol = protocol::OSC_MIDI2;
+  std::string host = "127.0.0.1";
+  int port{};
+  bool broadcast{};
+
+  boost::asio::io_context* io_context{};
+};
+
+struct dgram_observer_configuration
+{
+  std::string client_name = "libremidi client";
+
+  boost::asio::io_context* io_context{};
+};
+
+}

include/libremidi/backends/net/helpers.hpp

@@ -0,0 +1,94 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+#include <boost/asio/ip/udp.hpp>
+
+#include <memory>
+namespace stdx
+{ /*
+
+class boost_system_error_domain : public error_domain
+{
+public:
+  constexpr boost_system_error_domain() noexcept
+      : error_domain{
+            {1 - 0x3c223c0aa3cf45e5ULL, 1 - 0x80dac24345cfb9fcULL},
+            default_error_resource_management_t<detail::exception_ptr_wrapper>{}}
+  {
+  }
+
+  string_ref name() const noexcept override { return "boost::system_error domain"; }
+
+  bool equivalent(const error& lhs, const error& rhs) const noexcept override { return false; }
+
+  string_ref message(const error& e) const noexcept override {
+    auto err = e.m_value;
+
+  }
+
+  [[noreturn]] void throw_exception(const error& e) const override
+  {
+    assert(e.domain() == *this);
+    std::rethrow_exception(error_cast<detail::exception_ptr_wrapper>(e).get());
+  }
+};
+*/
+}
+
+NAMESPACE_LIBREMIDI
+{
+template <typename T>
+struct optionally_owned
+{
+public:
+  explicit optionally_owned(T* maybe_existing)
+      : m_storage{.ref = maybe_existing}
+  {
+    if (m_storage.ref)
+    {
+      m_ownership = unowned;
+      return;
+    }
+    else
+    {
+      std::destroy_at(&m_storage.ref);
+      std::construct_at<T>(reinterpret_cast<T*>(m_storage.object));
+      m_ownership = owned;
+    }
+  }
+
+  ~optionally_owned()
+  {
+    if (is_owned())
+      std::destroy_at(reinterpret_cast<T*>(m_storage.object));
+  }
+
+  T& get() noexcept
+  {
+    return *(is_owned() ? reinterpret_cast<T*>(&m_storage.object) : m_storage.ref);
+  }
+  const T& get() const noexcept
+  {
+    return *(is_owned() ? reinterpret_cast<T*>(&m_storage.object) : m_storage.ref);
+  }
+
+  optionally_owned(const optionally_owned&) = delete;
+  optionally_owned(optionally_owned&&) noexcept = delete;
+  optionally_owned& operator=(const optionally_owned&) = delete;
+  optionally_owned& operator=(optionally_owned&&) noexcept = delete;
+
+  bool is_owned() const noexcept { return m_ownership == owned; }
+
+private:
+  union
+  {
+    alignas(T) unsigned char object[sizeof(T)];
+    T* ref;
+  } m_storage;
+  enum
+  {
+    owned,
+    unowned
+  } m_ownership{};
+};
+}

include/libremidi/backends/net/midi_in.hpp

@@ -0,0 +1,437 @@
+#pragma once
+#include <libremidi/backends/net/config.hpp>
+#include <libremidi/backends/net/helpers.hpp>
+#include <libremidi/detail/midi_in.hpp>
+#include <libremidi/detail/midi_stream_decoder.hpp>
+
+#include <thread>
+NAMESPACE_LIBREMIDI
+{
+template <typename Impl, typename F>
+struct osc_parser
+{
+  [[no_unique_address]]
+  Impl impl;
+  F on_message;
+  std::string_view port_name;
+
+  stdx::error parse_bundle(const char* data, std::size_t sz)
+  {
+    std::string_view txt(data, sz);
+    if (!txt.starts_with("#bundle"))
+      return std::errc::bad_message;
+    return std::errc::protocol_not_supported;
+  }
+
+  stdx::error parse_message(const char* data, std::size_t sz)
+  {
+    const auto begin = data;
+    const auto end = data + sz;
+    std::size_t pattern_len = strnlen(data, sz);
+    if (pattern_len == sz)
+      return std::errc::bad_message;
+
+    if (auto pat = std::string_view(data, pattern_len); pat != port_name)
+      return std::errc::bad_address;
+
+    data += pattern_len;
+    for (; data < end; ++data)
+      if (*data == 0)
+        continue;
+      else
+        break;
+
+    // Now we shold reach the typetag beginning, ","
+    if (data == end)
+      return std::errc::bad_message;
+    if ((data - begin) % 4 != 0)
+      return std::errc::bad_message;
+    if (*data++ != ',')
+      return std::errc::bad_message;
+
+    // Count the ,mmmmm arguments... yummy
+    int num_msgs = 0;
+    for (; data < end; ++data)
+      if (*data == Impl::typetag)
+        num_msgs++;
+      else if (*data == 0)
+        break;
+      else
+        return std::errc::bad_message;
+
+    if (num_msgs == 0)
+      return std::errc::no_message;
+
+    // By now there's at least 5 bytes left as the ,mmm has to be round-up to 4 and padded with zeros:
+    if (end - data < 4)
+      return std::errc::bad_message;
+
+    switch ((1 + num_msgs) % 4)
+    {
+      case 0:
+        data += 4;
+        break;
+      case 1:
+        data += 3;
+        break;
+      case 2:
+        data += 2;
+        break;
+      case 3:
+        data += 1;
+        break;
+    }
+
+    // Data starts
+    return impl.process_midi_bytes(on_message, num_msgs, data, end - data);
+  }
+
+  stdx::error parse_int_message(const char* /* data */, std::size_t /* sz */)
+  {
+    return std::errc::protocol_not_supported;
+  }
+
+  stdx::error parse_packet(const char* data, std::size_t sz)
+  {
+    if (sz == 0)
+      return std::errc::no_message;
+
+    switch (data[0])
+    {
+      case '#':
+        return parse_bundle(data, sz);
+        break;
+      case '/':
+        return parse_message(data, sz);
+        break;
+      case '\0':
+        return parse_int_message(data, sz);
+        break;
+      default:
+        return std::errc::bad_message;
+    }
+  }
+};
+
+}
+
+NAMESPACE_LIBREMIDI::net
+{
+
+struct osc_parser_midi1
+{
+  static constexpr char typetag = 'm';
+
+  stdx::error
+  process_midi_bytes(auto& on_message, std::size_t num_msgs, const char* data, std::size_t sz)
+  {
+    if (sz != num_msgs * 4)
+      return std::errc::bad_message;
+
+    auto end = data + sz;
+    for (; data < end; data += 4)
+      on_message(data + 1);
+
+    return {};
+  }
+};
+
+class midi_in final
+    : public midi1::in_api
+    , public error_handler
+{
+public:
+  using midi_api::client_open_;
+  struct
+      : input_configuration
+      , dgram_input_configuration
+  {
+  } configuration;
+
+  explicit midi_in(input_configuration&& conf, dgram_input_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+      , m_ctx{configuration.io_context}
+      , m_socket{m_ctx.get()}
+  {
+    m_socket.open(boost::asio::ip::udp::v4());
+    m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
+
+    m_endpoint
+        = {boost::asio::ip::make_address(this->configuration.accept),
+           static_cast<unsigned short>(this->configuration.port)};
+
+    boost::system::error_code ec;
+    m_socket.bind(m_endpoint, ec);
+    if (ec != boost::system::error_code{})
+    {
+      client_open_ = std::errc::address_in_use;
+      return;
+    }
+
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_in() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::NETWORK; }
+
+  stdx::error open_port(const input_port&, std::string_view port) override
+  {
+    return open_virtual_port(port);
+  }
+
+  stdx::error open_virtual_port(std::string_view port) override
+  {
+    m_portname = std::string(port);
+
+    receive();
+
+    if (m_ctx.is_owned())
+    {
+      m_thread = std::jthread{[this, &ctx = m_ctx.get()] {
+        auto wg = boost::asio::make_work_guard(m_ctx);
+        ctx.run();
+      }};
+    }
+
+    return stdx::error{};
+  }
+
+  void receive()
+  {
+    m_socket.async_receive_from(
+        boost::asio::mutable_buffer(&m_data[0], std::size(m_data)), m_endpoint,
+        [this](auto ec, std::size_t sz) {
+      if (ec == boost::asio::error::operation_aborted)
+        return;
+
+      if (!ec && sz > 0)
+        this->on_bytes(reinterpret_cast<const char*>(m_data), sz);
+
+      this->receive();
+    });
+  }
+
+  stdx::error close_port() override
+  {
+    // FIXME async close
+    if (m_socket.is_open())
+      m_socket.close();
+    return {};
+  }
+
+  timestamp absolute_timestamp() const noexcept override
+  {
+    return std::chrono::steady_clock::now().time_since_epoch().count();
+  }
+
+  void on_bytes(const char* data, std::size_t size)
+  {
+    const auto on_msg = [this](const char* bytes) { this->on_message(bytes); };
+    osc_parser<osc_parser_midi1, decltype(on_msg)> parser{{}, on_msg, m_portname};
+    parser.parse_packet(data, size);
+  }
+
+  void on_message(const char* data)
+  {
+    // OSC enforces always 3 bytes
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = false,
+        .absolute_is_monotonic = false,
+        .has_samples = false,
+    };
+
+    static constexpr auto to_ns = []() {
+      return std::chrono::duration_cast<std::chrono::nanoseconds>(
+                 std::chrono::steady_clock::now().time_since_epoch())
+          .count();
+    };
+
+    auto ptr = reinterpret_cast<const uint8_t*>(data);
+    m_processing.on_bytes({ptr, ptr + 3}, m_processing.timestamp<timestamp_info>(to_ns, 0));
+  }
+
+  midi1::input_state_machine m_processing{this->configuration};
+
+  libremidi::optionally_owned<boost::asio::io_context> m_ctx;
+  boost::asio::ip::udp::endpoint m_endpoint;
+  boost::asio::ip::udp::socket m_socket;
+
+  std::jthread m_thread;
+
+  std::string m_portname;
+  alignas(16) unsigned char m_data[65535];
+};
+}
+
+NAMESPACE_LIBREMIDI::net_ump
+{
+struct osc_parser_midi2
+{
+  static constexpr char typetag = 'M';
+
+  stdx::error
+  process_midi_bytes(auto& on_message, std::size_t num_msgs, const char* data, std::size_t byte_sz)
+  {
+    if (byte_sz % 4 != 0)
+      return std::errc::bad_message;
+
+    auto sz = byte_sz / 4;
+
+    auto begin = reinterpret_cast<const uint32_t*>(data);
+    auto end = begin + sz;
+    std::size_t accounted = 0;
+    for (auto it = begin; it < end && accounted < num_msgs;)
+    {
+      const auto N = cmidi2_ump_get_message_size_bytes(it) / 4;
+      switch (N)
+      {
+        case 1:
+        case 2:
+        case 4:
+          if (it + N <= end)
+          {
+            on_message(it, N);
+            accounted++;
+          }
+          else
+            return std::errc::bad_message;
+          break;
+        default:
+          return std::errc::bad_message;
+      }
+      it += N;
+    }
+
+    return {};
+  }
+};
+
+class midi_in final
+    : public midi2::in_api
+    , public error_handler
+{
+public:
+  using midi_api::client_open_;
+  struct
+      : ump_input_configuration
+      , dgram_input_configuration
+  {
+  } configuration;
+
+  explicit midi_in(ump_input_configuration&& conf, dgram_input_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+      , m_ctx{configuration.io_context}
+      , m_socket{m_ctx.get()}
+  {
+    m_socket.open(boost::asio::ip::udp::v4());
+    m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
+
+    m_endpoint
+        = {boost::asio::ip::make_address(this->configuration.accept),
+           static_cast<unsigned short>(this->configuration.port)};
+
+    boost::system::error_code ec;
+    m_socket.bind(m_endpoint, ec);
+    if (ec != boost::system::error_code{})
+    {
+      client_open_ = std::errc::address_in_use;
+      return;
+    }
+
+    client_open_ = stdx::error{};
+  }
+
+  ~midi_in() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::NETWORK_UMP; }
+
+  stdx::error open_port(const input_port&, std::string_view port) override
+  {
+    return open_virtual_port(port);
+  }
+
+  stdx::error open_virtual_port(std::string_view port) override
+  {
+    m_portname = std::string(port);
+
+    receive();
+
+    if (m_ctx.is_owned())
+    {
+      m_thread = std::jthread{[this, &ctx = m_ctx.get()] {
+        auto wg = boost::asio::make_work_guard(m_ctx);
+        ctx.run();
+      }};
+    }
+    return stdx::error{};
+  }
+
+  void receive()
+  {
+    m_socket.async_receive_from(
+        boost::asio::mutable_buffer(&m_data[0], std::size(m_data)), m_endpoint,
+        [this](auto ec, std::size_t sz) {
+      if (ec == boost::asio::error::operation_aborted)
+        return;
+
+      if (!ec && sz > 0)
+        this->on_bytes(reinterpret_cast<const char*>(m_data), sz);
+
+      this->receive();
+    });
+  }
+
+  stdx::error close_port() override
+  {
+    // FIXME async close
+    if (m_ctx.is_owned())
+      m_ctx.get().stop();
+
+    if (m_socket.is_open())
+      m_socket.close();
+    return {};
+  }
+
+  timestamp absolute_timestamp() const noexcept override
+  {
+    return std::chrono::steady_clock::now().time_since_epoch().count();
+  }
+
+  void on_bytes(const char* data, std::size_t size)
+  {
+    const auto on_msg
+        = [this](const uint32_t* bytes, std::size_t N) { this->on_message(bytes, N); };
+    osc_parser<osc_parser_midi2, decltype(on_msg)> parser{{}, on_msg, m_portname};
+    parser.parse_packet(data, size);
+  }
+
+  void on_message(const uint32_t* ump, std::size_t sz)
+  {
+    static constexpr timestamp_backend_info timestamp_info{
+        .has_absolute_timestamps = false,
+        .absolute_is_monotonic = false,
+        .has_samples = false,
+    };
+
+    static constexpr auto to_ns = []() {
+      return std::chrono::duration_cast<std::chrono::nanoseconds>(
+                 std::chrono::steady_clock::now().time_since_epoch())
+          .count();
+    };
+
+    m_processing.on_bytes({ump, sz}, m_processing.timestamp<timestamp_info>(to_ns, 0));
+  }
+
+  midi2::input_state_machine m_processing{this->configuration};
+
+  libremidi::optionally_owned<boost::asio::io_context> m_ctx;
+  boost::asio::ip::udp::endpoint m_endpoint;
+  boost::asio::ip::udp::socket m_socket;
+
+  std::jthread m_thread;
+
+  std::string m_portname;
+  alignas(16) unsigned char m_data[65535];
+};
+}

include/libremidi/backends/net/midi_out.hpp

@@ -0,0 +1,288 @@
+#pragma once
+#include <libremidi/backends/net/config.hpp>
+#include <libremidi/backends/net/helpers.hpp>
+#include <libremidi/cmidi2.hpp>
+#include <libremidi/detail/midi_out.hpp>
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/udp.hpp>
+#include <boost/endian.hpp>
+
+NAMESPACE_LIBREMIDI::net
+{
+
+struct osc_midi1_packet
+{
+  stdx::error init_packet(std::string_view osc_pattern)
+  {
+    int i = 0;
+    for (; i < std::ssize(osc_pattern); i++)
+      if (osc_pattern.data()[i] != 0)
+        bytes[i] = osc_pattern.data()[i];
+      else
+        break;
+    bytes[i] = 0;
+    while (i % 4 != 3)
+    {
+      ++i;
+      bytes[i] = 0;
+    }
+
+    bytes[++i] = ',';
+    bytes[++i] = 'm';
+    bytes[++i] = 0;
+    bytes[++i] = 0;
+
+    // MIDI message (m) spec: port n°, status byte, data 1, data 2
+    bytes[++i] = 0;
+    message_size = ++i + 3;
+
+    return stdx::error{}; // FIXME
+  }
+
+  stdx::error deinit()
+  {
+    message_size = 0;
+    return stdx::error{};
+  }
+
+  stdx::error set_packet_content(const unsigned char* message, size_t size)
+  {
+    if (message_size == 0)
+      return std::errc::not_connected;
+
+    if (size != 3)
+      return std::errc::message_size;
+
+    std::memcpy(this->bytes + message_size - 3, message, 3);
+
+    return stdx::error{};
+  }
+
+  std::span<const char> get_data() { return std::span(this->bytes, this->message_size); }
+  char bytes[512 + 8 + 8];
+  int message_size{};
+};
+
+class midi_out final
+    : public midi1::out_api
+    , public error_handler
+{
+public:
+  struct
+      : output_configuration
+      , dgram_output_configuration
+  {
+  } configuration;
+
+  midi_out(output_configuration&& conf, dgram_output_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+      , ctx{configuration.io_context}
+      , m_socket{ctx.get()}
+  {
+    m_socket.open(boost::asio::ip::udp::v4());
+    m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
+    m_socket.set_option(boost::asio::socket_base::broadcast(true));
+
+    m_endpoint
+        = {boost::asio::ip::make_address(this->configuration.host),
+           static_cast<unsigned short>(this->configuration.port)};
+
+    this->client_open_ = stdx::error{};
+  }
+
+  ~midi_out() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::NETWORK; }
+
+  stdx::error open_port(const output_port& /* port */, std::string_view portName) override
+  {
+    return open_virtual_port(portName);
+  }
+
+  stdx::error open_virtual_port(std::string_view portName) override
+  {
+    // Random arbitrary limit to avoid abuse
+    if (portName.size() >= 512)
+      return std::errc::invalid_argument;
+
+    pkt.init_packet(portName);
+
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override
+  {
+    pkt.deinit();
+    // FIXME async close
+    if (m_socket.is_open())
+      m_socket.close();
+    return {};
+  }
+
+  stdx::error send_message(const unsigned char* message, size_t size) override
+  {
+    if (auto err = pkt.set_packet_content(message, size); err != stdx::error{})
+      return err;
+
+    auto dat = pkt.get_data();
+    boost::system::error_code ec;
+    m_socket.send_to(boost::asio::const_buffer(dat.data(), dat.size()), m_endpoint, 0, ec);
+    return stdx::error{}; // FIXME
+  }
+
+  stdx::error schedule_message(int64_t, const unsigned char*, size_t) override
+  {
+    int ret = 0;
+    return from_errc(ret);
+  }
+
+  libremidi::optionally_owned<boost::asio::io_context> ctx;
+  boost::asio::ip::udp::endpoint m_endpoint;
+  boost::asio::ip::udp::socket m_socket;
+
+  osc_midi1_packet pkt;
+};
+
+}
+
+NAMESPACE_LIBREMIDI::net_ump
+{
+struct osc_midi2_packet
+{
+  stdx::error init_packet(std::string_view osc_pattern)
+  {
+    int i = 0;
+    for (; i < std::ssize(osc_pattern); i++)
+      if (osc_pattern.data()[i] != 0)
+        bytes[i] = osc_pattern.data()[i];
+      else
+        break;
+    bytes[i] = 0;
+    while (i % 4 != 3)
+    {
+      ++i;
+      bytes[i] = 0;
+    }
+
+    bytes[++i] = ',';
+    bytes[++i] = 'M';
+    bytes[++i] = 0;
+    bytes[++i] = 0;
+
+    // MIDI 2 message (M) spec: an UMP
+    header_size = ++i;
+
+    return stdx::error{}; // FIXME
+  }
+
+  stdx::error deinit()
+  {
+    header_size = 0;
+    return stdx::error{};
+  }
+
+  stdx::error set_packet_content(const uint32_t* message, size_t size)
+  {
+    if (header_size == 0)
+      return std::errc::not_connected;
+
+    if (size > 4)
+      return std::errc::message_size;
+
+    message_size = 4 * size;
+
+    std::memcpy(this->bytes + header_size, message, message_size);
+
+    return stdx::error{};
+  }
+
+  std::span<const char> get_data()
+  {
+    return std::span(this->bytes, this->header_size + this->message_size);
+  }
+  char bytes[512 + 8 + 64];
+  int header_size{};
+  int message_size{};
+};
+
+class midi_out final
+    : public midi2::out_api
+    , public error_handler
+{
+public:
+  struct
+      : output_configuration
+      , dgram_output_configuration
+  {
+  } configuration;
+
+  midi_out(output_configuration&& conf, dgram_output_configuration&& apiconf)
+      : configuration{std::move(conf), std::move(apiconf)}
+      , ctx{configuration.io_context}
+      , m_socket{ctx.get()}
+  {
+    m_socket.open(boost::asio::ip::udp::v4());
+    m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
+    m_socket.set_option(boost::asio::socket_base::broadcast(true));
+
+    m_endpoint
+        = {boost::asio::ip::make_address(this->configuration.host),
+           static_cast<unsigned short>(this->configuration.port)};
+
+    this->client_open_ = stdx::error{};
+  }
+
+  ~midi_out() override { close_port(); }
+
+  libremidi::API get_current_api() const noexcept override { return libremidi::API::NETWORK_UMP; }
+
+  stdx::error open_port(const output_port& /* port */, std::string_view portName) override
+  {
+    return open_virtual_port(portName);
+  }
+
+  stdx::error open_virtual_port(std::string_view portName) override
+  {
+    // Random arbitrary limit to avoid abuse
+    if (portName.size() >= 512)
+      return std::errc::invalid_argument;
+
+    pkt.init_packet(portName);
+
+    return stdx::error{};
+  }
+
+  stdx::error close_port() override
+  {
+    pkt.deinit();
+    if (m_socket.is_open())
+      m_socket.close();
+    return {};
+  }
+
+  stdx::error send_ump(const uint32_t* message, size_t size) override
+  {
+    if (auto err = pkt.set_packet_content(message, size); err != stdx::error{})
+      return err;
+
+    auto dat = pkt.get_data();
+    boost::system::error_code ec;
+    m_socket.send_to(boost::asio::const_buffer(dat.data(), dat.size()), m_endpoint, 0, ec);
+    return stdx::error{}; // FIXME
+  }
+
+  stdx::error schedule_ump(int64_t, const uint32_t*, size_t) override
+  {
+    int ret = 0;
+    return from_errc(ret);
+  }
+
+  libremidi::optionally_owned<boost::asio::io_context> ctx;
+  boost::asio::ip::udp::endpoint m_endpoint;
+  boost::asio::ip::udp::socket m_socket;
+
+  osc_midi2_packet pkt;
+};
+
+}

include/libremidi/backends/net/observer.hpp

@@ -0,0 +1,14 @@
+#pragma once
+#include <libremidi/backends/dummy.hpp>
+
+NAMESPACE_LIBREMIDI::net
+{
+using net_observer_configuration = libremidi::dummy_configuration;
+using observer = libremidi::observer_dummy;
+}
+
+NAMESPACE_LIBREMIDI::net_ump
+{
+using net_observer_configuration = libremidi::dummy_configuration;
+using observer = libremidi::observer_dummy;
+}

include/libremidi/backends/network.hpp

@@ -0,0 +1,26 @@
+#pragma once
+#include <libremidi/backends/dummy.hpp>
+#include <libremidi/backends/net/config.hpp>
+#include <libremidi/backends/net/midi_in.hpp>
+#include <libremidi/backends/net/midi_out.hpp>
+#include <libremidi/backends/net/observer.hpp>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::net
+{
+struct backend
+{
+  using midi_in = libremidi::net::midi_in;
+  using midi_out = libremidi::net::midi_out;
+  using midi_observer = libremidi::net::observer;
+  using midi_in_configuration = libremidi::net::dgram_input_configuration;
+  using midi_out_configuration = libremidi::net::dgram_output_configuration;
+  using midi_observer_configuration = libremidi::net::net_observer_configuration;
+  static const constexpr auto API = libremidi::API::NETWORK;
+  static const constexpr std::string_view name = "network";
+  static const constexpr std::string_view display_name = "Network";
+
+  static inline bool available() noexcept { return true; }
+};
+}

include/libremidi/backends/network_ump.hpp

@@ -0,0 +1,25 @@
+#pragma once
+#include <libremidi/backends/net/config.hpp>
+#include <libremidi/backends/net/midi_in.hpp>
+#include <libremidi/backends/net/midi_out.hpp>
+#include <libremidi/backends/net/observer.hpp>
+
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::net_ump
+{
+struct backend
+{
+  using midi_in = libremidi::net_ump::midi_in;
+  using midi_out = libremidi::net_ump::midi_out;
+  using midi_observer = libremidi::net_ump::observer;
+  using midi_in_configuration = libremidi::net_ump::dgram_input_configuration;
+  using midi_out_configuration = libremidi::net_ump::dgram_output_configuration;
+  using midi_observer_configuration = libremidi::net_ump::net_observer_configuration;
+  static const constexpr auto API = libremidi::API::NETWORK_UMP;
+  static const constexpr std::string_view name = "network (UMP)";
+  static const constexpr std::string_view display_name = "Network (UMP)";
+
+  static inline bool available() noexcept { return true; }
+};
+}

include/libremidi/backends/pipewire.hpp

@@ -7,7 +7,9 @@
 #include <libremidi/backends/pipewire/midi_out.hpp>
 #include <libremidi/backends/pipewire/observer.hpp>
 
-namespace libremidi::pipewire
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::pipewire
 {
 struct backend
 {
@@ -18,8 +20,8 @@ struct backend
   using midi_out_configuration = pipewire_output_configuration;
   using midi_observer_configuration = pipewire_observer_configuration;
   static const constexpr auto API = libremidi::API::PIPEWIRE;
-  static const constexpr auto name = "pipewire";
+  static const constexpr std::string_view name = "pipewire";
-  static const constexpr auto display_name = "PipeWire";
+  static const constexpr std::string_view display_name = "PipeWire";
 
   static inline bool available() noexcept
   {

include/libremidi/backends/pipewire/config.hpp

@@ -12,7 +12,7 @@ struct pw_filter;
 struct spa_io_position;
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 using pipewire_callback_function = std::function<void(spa_io_position*)>;
 struct pipewire_callback
@@ -27,8 +27,8 @@ struct pipewire_input_configuration
 
   pw_main_loop* context{};
   pw_filter* filter{};
-  std::function<void(pipewire_callback)> set_process_func;
+  std::function<void(pipewire_callback)> set_process_func{};
-  std::function<void(int64_t)> clear_process_func;
+  std::function<void(int64_t)> clear_process_func{};
 };
 
 struct pipewire_output_configuration
@@ -37,8 +37,8 @@ struct pipewire_output_configuration
 
   pw_main_loop* context{};
   pw_filter* filter{};
-  std::function<void(pipewire_callback)> set_process_func;
+  std::function<void(pipewire_callback)> set_process_func{};
-  std::function<void(int64_t)> clear_process_func;
+  std::function<void(int64_t)> clear_process_func{};
 
   int64_t output_buffer_size{65536};
 };

include/libremidi/backends/pipewire/context.hpp

@@ -1,6 +1,7 @@
 #pragma once
 #include <libremidi/backends/linux/pipewire.hpp>
 #include <libremidi/detail/memory.hpp>
+#include <libremidi/error.hpp>
 
 #include <pipewire/filter.h>
 #include <pipewire/pipewire.h>
@@ -17,13 +18,14 @@
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include <spa/param/audio/format-utils.h>
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <typename K, typename V>
 using hash_map = std::unordered_map<K, V>;
@@ -78,11 +80,11 @@ struct pipewire_context
   struct graph
   {
     mutable std::mutex mtx;
-    libremidi::hash_map<uint32_t, node> physical_audio;
+    libremidi::hash_map<uint64_t, node> physical_audio;
-    libremidi::hash_map<uint32_t, node> physical_midi;
+    libremidi::hash_map<uint64_t, node> physical_midi;
-    libremidi::hash_map<uint32_t, node> software_audio;
+    libremidi::hash_map<uint64_t, node> software_audio;
-    libremidi::hash_map<uint32_t, node> software_midi;
+    libremidi::hash_map<uint64_t, node> software_midi;
-    libremidi::hash_map<uint32_t, port_info> port_cache;
+    libremidi::hash_map<uint64_t, port_info> port_cache;
 
     void for_each_port(auto func)
     {
@@ -122,13 +124,13 @@ struct pipewire_context
   }
 
   explicit pipewire_context(std::shared_ptr<pipewire_instance> inst)
-      : global_instance{inst}
+      : global_instance{std::move(inst)}
       , owns_main_loop{true}
   {
     this->main_loop = pw.main_loop_new(nullptr);
     if (!this->main_loop)
     {
-      // libremidi::logger().error("PipeWire: main_loop_new failed!");
+      // libremidi::logger().libremidi_handle_error("main_loop_new failed!");
       return;
     }
     initialize();
@@ -139,28 +141,28 @@ struct pipewire_context
     this->lp = pw.main_loop_get_loop(this->main_loop);
     if (!lp)
     {
-      // libremidi::logger().error("PipeWire: main_loop_get_loop failed!");
+      // libremidi::logger().libremidi_handle_error("main_loop_get_loop failed!");
       return;
     }
 
     this->context = pw.context_new(lp, nullptr, 0);
     if (!this->context)
     {
-      // libremidi::logger().error("PipeWire: context_new failed!");
+      // libremidi::logger().libremidi_handle_error("context_new failed!");
       return;
     }
 
     this->core = pw.context_connect(this->context, nullptr, 0);
     if (!this->core)
     {
-      // libremidi::logger().error("PipeWire: context_connect failed!");
+      // libremidi::logger().libremidi_handle_error("context_connect failed!");
       return;
     }
 
     this->registry = pw_core_get_registry(this->core, PW_VERSION_REGISTRY, 0);
     if (!this->registry)
     {
-      // libremidi::logger().error("PipeWire: core_get_registry failed!");
+      // libremidi::logger().libremidi_handle_error("core_get_registry failed!");
       return;
     }
 
@@ -286,7 +288,7 @@ struct pipewire_context
     spa_hook_remove(&core_listener);
   }
 
-  [[nodiscard]] pw_proxy* link_ports(uint32_t out_port, uint32_t in_port)
+  [[nodiscard]] pw_proxy* link_ports(uint64_t out_port, uint64_t in_port)
   {
     auto props = pw.properties_new(
         PW_KEY_LINK_OUTPUT_PORT, std::to_string(out_port).c_str(), PW_KEY_LINK_INPUT_PORT,
@@ -297,7 +299,6 @@ struct pipewire_context
 
     if (!proxy)
     {
-      std::cerr << "PipeWire: could not allocate link\n";
       pw.properties_free(props);
       return nullptr;
     }
@@ -361,6 +362,8 @@ struct pipewire_context
           return &this->current_graph.physical_audio[nid];
         else if (p.format.find("midi") != p.format.npos)
           return &this->current_graph.physical_midi[nid];
+        else if (p.format.find("UMP") != p.format.npos)
+          return &this->current_graph.physical_midi[nid];
       }
       else
       {
@@ -368,6 +371,8 @@ struct pipewire_context
           return &this->current_graph.software_audio[nid];
         else if (p.format.find("midi") != p.format.npos)
           return &this->current_graph.software_midi[nid];
+        else if (p.format.find("UMP") != p.format.npos)
+          return &this->current_graph.software_midi[nid];
       }
       return nullptr;
     };
@@ -453,12 +458,12 @@ struct pipewire_filter
   }* port{};
 
   explicit pipewire_filter(std::shared_ptr<pipewire_context> loop)
-      : loop{loop}
+      : loop{std::move(loop)}
   {
   }
 
   explicit pipewire_filter(std::shared_ptr<pipewire_context> loop, pw_filter* filter)
-      : loop{loop}
+      : loop{std::move(loop)}
       , filter{filter}
   {
   }
@@ -476,7 +481,7 @@ struct pipewire_filter
             PW_KEY_MEDIA_TYPE, "Midi",
             PW_KEY_MEDIA_CATEGORY, "Filter",
             PW_KEY_MEDIA_ROLE, "DSP",
-            PW_KEY_MEDIA_NAME, "libremidi",
+            PW_KEY_MEDIA_NAME, "",
 #if defined(PW_KEY_NODE_LOCK_RATE)
             PW_KEY_NODE_LOCK_RATE, "true",
 #endif
@@ -498,7 +503,8 @@ struct pipewire_filter
       pw.filter_destroy(this->filter);
   }
 
-  void create_local_port(std::string_view port_name, spa_direction direction)
+  stdx::error
+  create_local_port(std::string_view port_name, spa_direction direction, const char* format)
   {
     // clang-format off
     this->port = (struct port*)pw.filter_add_port(
@@ -507,15 +513,17 @@ struct pipewire_filter
         PW_FILTER_PORT_FLAG_MAP_BUFFERS,
         sizeof(struct port),
         pw.properties_new(
-            PW_KEY_FORMAT_DSP, "8 bit raw midi",
+            PW_KEY_FORMAT_DSP, format,
             PW_KEY_PORT_NAME, port_name.data(),
             nullptr),
         nullptr, 0);
     // clang-format on
-    assert(port);
+    if (!port)
+      return std::errc::invalid_argument;
+    return stdx::error{};
   }
 
-  void set_port_buffer(int bytes)
+  void set_port_buffer(int64_t bytes)
   {
     uint8_t buffer[1024];
     struct spa_pod_builder builder;
@@ -537,31 +545,41 @@ struct pipewire_filter
     pw.filter_update_params(this->filter, this->port, params, 1);
   }
 
-  void remove_port()
+  stdx::error remove_port()
   {
     assert(this->port);
-    pw.filter_remove_port(this->port);
+    int ret = pw.filter_remove_port(this->port);
     this->port = nullptr;
+    return from_errc(ret);
   }
 
-  void rename_port(std::string_view port_name)
+  stdx::error rename_port(std::string_view port_name)
+  {
+    if (this->port)
     {
-    assert(this->port);
       spa_dict_item items[1] = {
           SPA_DICT_ITEM_INIT(PW_KEY_PORT_NAME, port_name.data()),
       };
 
       auto properties = SPA_DICT_INIT(items, 1);
-    pw.filter_update_properties(this->filter, this->port, &properties);
+      int ret = pw.filter_update_properties(this->filter, this->port, &properties);
-    this->port = nullptr;
+      return from_errc(ret);
+    }
+    else
+    {
+      return std::errc::not_connected;
+    }
   }
 
-  void start_filter()
+  [[nodiscard]] stdx::error start_filter()
   {
-    if (pw.filter_connect(this->filter, PW_FILTER_FLAG_RT_PROCESS, NULL, 0) < 0)
+    if (int ret = pw.filter_connect(this->filter, PW_FILTER_FLAG_RT_PROCESS, NULL, 0); ret < 0)
     {
-      std::cerr << "can't connect\n";
+      return from_errc(ret);
-      return;
+    }
+    else
+    {
+      return stdx::error{};
     }
   }
 

include/libremidi/backends/pipewire/helpers.hpp

@@ -2,17 +2,21 @@
 
 #include <libremidi/backends/linux/helpers.hpp>
 #include <libremidi/backends/linux/pipewire.hpp>
+#include <libremidi/backends/pipewire/config.hpp>
 #include <libremidi/backends/pipewire/context.hpp>
 #include <libremidi/detail/memory.hpp>
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/semaphore.hpp>
 
 #include <atomic>
-#include <semaphore>
-#include <stop_token>
 #include <thread>
 
-namespace libremidi
+#if defined(__clang__)
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wsign-compare"
+#endif
+
+NAMESPACE_LIBREMIDI
 {
 struct pipewire_helpers
 {
@@ -55,17 +59,17 @@ struct pipewire_helpers
   }
 
   template <typename Self>
-  void create_filter(Self& self)
+  stdx::error create_filter(Self& self)
   {
     if (this->filter)
-      return;
+      return stdx::error{};
 
     auto& configuration = self.configuration;
     if (configuration.context && configuration.filter && configuration.set_process_func)
     {
       this->filter = std::make_unique<pipewire_filter>(this->global_context, configuration.filter);
 
-      pipewire_callback cbs{
+      libremidi::pipewire_callback cbs{
           .token = this_instance,
           .callback = [&self, p = std::weak_ptr{canary}](spa_io_position* nf) -> void {
         if (auto pt = p.lock())
@@ -90,8 +94,9 @@ struct pipewire_helpers
 #pragma GCC diagnostic pop
 
       this->filter->create_filter(self.configuration.client_name, filter_events, &self);
-      this->filter->start_filter();
+      return this->filter->start_filter();
     }
+    return stdx::error{};
   }
 
   template <typename Self>
@@ -117,10 +122,10 @@ struct pipewire_helpers
   }
 
   template <typename Self>
-  int create_context(Self& self)
+  stdx::error create_context(Self& self)
   {
     if (this->global_context)
-      return 0;
+      return stdx::error{};
 
     // Initialize PipeWire client
     auto& configuration = self.configuration;
@@ -133,7 +138,10 @@ struct pipewire_helpers
       this->global_instance = std::make_shared<pipewire_instance>();
       this->global_context = std::make_shared<pipewire_context>(this->global_instance);
     }
-    return 0;
+    if (!this->global_context->main_loop)
+      return std::errc::connection_refused;
+
+    return stdx::error{};
   }
 
   void destroy_context()
@@ -170,7 +178,9 @@ struct pipewire_helpers
           {
             int result = pw_loop_iterate(lp, 0);
             if (result < 0)
-              std::cerr << "pw_loop_iterate: " << spa_strerror(result) << "\n";
+            {
+              LIBREMIDI_LOG(spa_strerror(result));
+            }
           }
           fds[0].revents = 0;
         }
@@ -190,7 +200,8 @@ struct pipewire_helpers
   }
 
   template <typename Self>
-  bool create_local_port(Self& self, std::string_view portName, spa_direction direction)
+  stdx::error create_local_port(
+      Self& self, std::string_view portName, spa_direction direction, const char* format)
   {
     assert(this->global_context);
     assert(this->filter);
@@ -200,22 +211,23 @@ struct pipewire_helpers
 
     if (!this->filter->port)
     {
-      this->filter->create_local_port(portName.data(), direction);
+      auto ret = this->filter->create_local_port(portName.data(), direction, format);
-    }
+      if (ret != stdx::error{})
-
-    if (!this->filter->port)
       {
-      self.template error<driver_error>(self.configuration, "PipeWire: error creating port");
+        self.libremidi_handle_error(self.configuration, "error creating port");
-      return false;
+        return ret;
       }
-    return true;
     }
 
-  void add_callbacks(const observer_configuration& conf)
+    return stdx::error{};
+  }
+
+  template <libremidi::API Api>
+  void add_callbacks(std::string format, const observer_configuration& conf)
   {
     assert(global_context);
-    global_context->on_port_added = [&conf](const pipewire_context::port_info& port) {
+    global_context->on_port_added = [format, &conf](const pipewire_context::port_info& port) {
-      if (port.format.find("midi") == std::string::npos)
+      if (port.format.find(format) == std::string::npos)
         return;
 
       bool unfiltered = conf.track_any;
@@ -226,18 +238,18 @@ struct pipewire_helpers
         if (port.direction == SPA_DIRECTION_INPUT)
         {
           if (conf.output_added)
-            conf.output_added(to_port_info<SPA_DIRECTION_INPUT>(port));
+            conf.output_added(to_port_info<SPA_DIRECTION_INPUT, Api>(port));
         }
         else
         {
           if (conf.input_added)
-            conf.input_added(to_port_info<SPA_DIRECTION_OUTPUT>(port));
+            conf.input_added(to_port_info<SPA_DIRECTION_OUTPUT, Api>(port));
         }
       }
     };
 
-    global_context->on_port_removed = [&conf](const pipewire_context::port_info& port) {
+    global_context->on_port_removed = [format, &conf](const pipewire_context::port_info& port) {
-      if (port.format.find("midi") == std::string::npos)
+      if (port.format.find(format) == std::string::npos)
         return;
 
       bool unfiltered = conf.track_any;
@@ -248,12 +260,12 @@ struct pipewire_helpers
         if (port.direction == SPA_DIRECTION_INPUT)
         {
           if (conf.output_removed)
-            conf.output_removed(to_port_info<SPA_DIRECTION_INPUT>(port));
+            conf.output_removed(to_port_info<SPA_DIRECTION_INPUT, Api>(port));
         }
         else
         {
           if (conf.input_removed)
-            conf.input_removed(to_port_info<SPA_DIRECTION_OUTPUT>(port));
+            conf.input_removed(to_port_info<SPA_DIRECTION_OUTPUT, Api>(port));
         }
       }
     };
@@ -293,12 +305,12 @@ struct pipewire_helpers
     }
   }
 
-  void do_close_port()
+  stdx::error do_close_port()
   {
     if (!this->filter)
-      return;
+      return stdx::error{};
     if (!this->filter->port)
-      return;
+      return stdx::error{};
 
     if (!this->global_context->owns_main_loop)
     {
@@ -307,13 +319,19 @@ struct pipewire_helpers
     }
 
     unlink_ports();
-    this->filter->remove_port();
+    return this->filter->remove_port();
   }
 
-  void rename_port(std::string_view port_name)
+  stdx::error rename_port(std::string_view port_name)
   {
     if (this->filter)
-      this->filter->rename_port(port_name);
+    {
+      return this->filter->rename_port(port_name);
+    }
+    else
+    {
+      return std::errc::not_connected;
+    }
   }
 
   void unlink_ports()
@@ -325,7 +343,7 @@ struct pipewire_helpers
     }
   }
 
-  bool link_ports(auto& self, const input_port& in_port)
+  stdx::error link_ports(auto& self, const input_port& in_port)
   {
     // Wait for the pipewire server to send us back our node's info
     for (int i = 0; i < 1000; i++)
@@ -335,19 +353,13 @@ struct pipewire_helpers
     auto& midi = this->global_context->current_graph.software_midi;
     auto node_it = midi.find(this_node);
     if (node_it == midi.end())
-    {
+      return std::errc::invalid_argument;
-      std::cerr << "Node " << this_node << " not found! \n";
-      return false;
-    }
 
     // Wait for the pipewire server to send us back our node's ports
     this->filter->synchronize_ports(node_it->second);
 
     if (node_it->second.inputs.empty())
-    {
+      return std::errc::no_link;
-      std::cerr << "Node " << this_node << " has no ports! \n";
-      return false;
-    }
 
     // Link ports
     const auto& p = node_it->second.inputs.front();
@@ -355,16 +367,16 @@ struct pipewire_helpers
     pw_loop_iterate(this->global_context->lp, 1);
     if (!link)
     {
-      self.template error<invalid_parameter_error>(
+      self.libremidi_handle_error(
           self.configuration,
-          "PipeWire: could not connect to port: " + in_port.port_name + " -> " + p.port_name);
+          "could not connect to port: " + in_port.port_name + " -> " + p.port_name);
-      return false;
+      return std::errc::no_link;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  bool link_ports(auto& self, const output_port& out_port)
+  stdx::error link_ports(auto& self, const output_port& out_port)
   {
     // Wait for the pipewire server to send us back our node's info
     for (int i = 0; i < 1000; i++)
@@ -375,8 +387,7 @@ struct pipewire_helpers
     auto node_it = midi.find(this_node);
     if (node_it == midi.end())
     {
-      std::cerr << "Node " << this_node << " not found! \n";
+      return std::errc::invalid_argument;
-      return false;
     }
 
     // Wait for the pipewire server to send us back our node's ports
@@ -384,8 +395,7 @@ struct pipewire_helpers
 
     if (node_it->second.outputs.empty())
     {
-      std::cerr << "Node " << this_node << " has no ports! \n";
+      return std::errc::no_link;
-      return false;
     }
 
     // Link ports
@@ -394,16 +404,16 @@ struct pipewire_helpers
     pw_loop_iterate(this->global_context->lp, 1);
     if (!link)
     {
-      self.template error<invalid_parameter_error>(
+      self.libremidi_handle_error(
           self.configuration,
-          "PipeWire: could not connect to port: " + p.port_name + " -> " + out_port.port_name);
+          "could not connect to port: " + p.port_name + " -> " + out_port.port_name);
-      return false;
+      return std::errc::no_link;
     }
 
-    return true;
+    return stdx::error{};
   }
 
-  template <spa_direction Direction>
+  template <spa_direction Direction, libremidi::API Api>
   static auto to_port_info(const pipewire_context::port_info& port)
       -> std::conditional_t<Direction == SPA_DIRECTION_OUTPUT, input_port, output_port>
   {
@@ -420,6 +430,7 @@ struct pipewire_helpers
     }
 
     return {{
+        .api = Api,
         .client = 0,
         .port = port.id,
         .manufacturer = "",
@@ -431,8 +442,11 @@ struct pipewire_helpers
 
   // Note: keep in mind that an "input" port for us (e.g. a keyboard that goes to the computer)
   // is an "output" port from the point of view of pipewire as data will come out of it
-  template <spa_direction Direction>
+  template <spa_direction Direction, libremidi::API Api>
-  static auto get_ports(const pipewire_context& ctx) noexcept -> std::vector<
+  static auto get_ports(
+      std::string_view format, const observer_configuration& conf,
+      const pipewire_context& ctx) noexcept
+      -> std::vector<
           std::conditional_t<Direction == SPA_DIRECTION_OUTPUT, input_port, output_port>>
   {
     std::vector<std::conditional_t<Direction == SPA_DIRECTION_OUTPUT, input_port, output_port>>
@@ -440,20 +454,25 @@ struct pipewire_helpers
 
     {
       std::lock_guard _{ctx.current_graph.mtx};
+      if (conf.track_any || conf.track_hardware)
         for (auto& node : ctx.current_graph.physical_midi)
         {
-        for (auto& p :
+          for (auto& port :
                (Direction == SPA_DIRECTION_INPUT ? node.second.inputs : node.second.outputs))
           {
-          ret.push_back(to_port_info<Direction>(p));
+            if (port.format.find(format) != std::string::npos)
+              ret.push_back(to_port_info<Direction, Api>(port));
           }
         }
+
+      if (conf.track_any || conf.track_virtual)
         for (auto& node : ctx.current_graph.software_midi)
         {
-        for (auto& p :
+          for (auto& port :
                (Direction == SPA_DIRECTION_INPUT ? node.second.inputs : node.second.outputs))
           {
-          ret.push_back(to_port_info<Direction>(p));
+            if (port.format.find(format) != std::string::npos)
+              ret.push_back(to_port_info<Direction, Api>(port));
           }
         }
     }
@@ -462,3 +481,7 @@ struct pipewire_helpers
   }
 };
 }
+
+#if defined(__clang__)
+  #pragma clang diagnostic pop
+#endif