virtual ports working - ui needs some work

.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/*

include/libremidi/api-c.h

@@ -1,13 +1,15 @@
 #pragma once
+#ifndef LIBREMIDI_API_C_H
+#define LIBREMIDI_API_C_H
 
-#if __cplusplus
+#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.
-typedef enum libremidi_api
+enum libremidi_api
 {
   UNSPECIFIED = 0x0, /*!< Search for a working compiled API. */
 
@@ -22,6 +24,8 @@ typedef enum libremidi_api
   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 */
@@ -30,10 +34,15 @@ typedef enum libremidi_api
   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. */
-} libremidi_api;
+};
 
-#if __cplusplus
+typedef enum libremidi_api libremidi_api;
+
+#if __cplusplus && !defined(LIBREMIDI_MODULE_BUILD)
 }
 #endif
+#endif

include/libremidi/api.hpp

@@ -2,11 +2,10 @@
 #include <libremidi/api-c.h>
 #include <libremidi/config.hpp>
 
-#include <any>
 #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
@@ -31,9 +30,6 @@ LIBREMIDI_EXPORT std::vector<libremidi::API> available_apis() noexcept;
 */
 LIBREMIDI_EXPORT std::vector<libremidi::API> available_ump_apis() noexcept;
 
-LIBREMIDI_EXPORT
-libremidi::API midi_api(const std::any& conf);
-
 //! A static function to determine the current version.
 LIBREMIDI_EXPORT std::string_view get_version() noexcept;
 
@@ -64,10 +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
@@ -83,7 +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

@@ -1,7 +1,6 @@
 #pragma once
 #include <libremidi/config.hpp>
 
-#include <any>
 #include <tuple>
 
 #if !__has_include(<weak_libjack.h>) && !__has_include(<jack/jack.h>)
@@ -30,10 +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)
@@ -45,6 +50,10 @@
   #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>
 #endif
@@ -68,7 +77,11 @@
   #include <libremidi/backends/network_ump.hpp>
 #endif
 
-namespace libremidi
+#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.
@@ -80,7 +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)
     ,
@@ -98,6 +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{}
@@ -121,6 +138,10 @@ static constexpr auto available_backends = make_tl(
 #if defined(LIBREMIDI_NETWORK)
     ,
     net::backend{}
+#endif
+#if defined(LIBREMIDI_ANDROID)
+    ,
+    android::backend{}
 #endif
     ,
     dummy_backend{});
@@ -146,7 +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
     ,
@@ -163,6 +184,14 @@ static constexpr auto available_backends = make_tl(
 #if defined(LIBREMIDI_NETWORK)
     ,
     net_ump::backend{}
+#endif
+#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{});
@@ -173,7 +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>
@@ -202,10 +231,10 @@ auto for_backend(libremidi::API api, F&& f)
   midi2::for_backend(api, f);
 }
 
-void for_input_configuration(auto f, std::any& api_conf)
+void for_input_configuration(auto f, libremidi::input_api_configuration& api_conf)
 {
   auto from_api = [&]<typename T>(T& /*backend*/) mutable {
-    if (auto conf = std::any_cast<typename T::midi_in_configuration>(&api_conf))
+    if (auto conf = get_if<typename T::midi_in_configuration>(&api_conf))
     {
       f(*conf);
       return true;
@@ -217,10 +246,10 @@ void for_input_configuration(auto f, std::any& api_conf)
   std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi2::available_backends);
 }
 
-void for_output_configuration(auto f, std::any& api_conf)
+void for_output_configuration(auto f, libremidi::output_api_configuration& api_conf)
 {
   auto from_api = [&]<typename T>(T& /*backend*/) mutable {
-    if (auto conf = std::any_cast<typename T::midi_out_configuration>(&api_conf))
+    if (auto conf = get_if<typename T::midi_out_configuration>(&api_conf))
     {
       f(*conf);
       return true;
@@ -232,10 +261,10 @@ void for_output_configuration(auto f, std::any& api_conf)
   std::apply([&](auto&&... b) { return (from_api(b) || ...); }, midi2::available_backends);
 }
 
-void for_observer_configuration(auto f, std::any& api_conf)
+void for_observer_configuration(auto f, libremidi::observer_api_configuration& api_conf)
 {
   auto from_api = [&]<typename T>(T& /*backend*/) mutable {
-    if (auto conf = std::any_cast<typename T::midi_observer_configuration>(&api_conf))
+    if (auto conf = get_if<typename T::midi_observer_configuration>(&api_conf))
     {
       f(*conf);
       return true;

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
 {
 
 /**

include/libremidi/backends/alsa_raw/helpers.hpp

@@ -2,10 +2,17 @@
 #include <libremidi/backends/linux/alsa.hpp>
 #include <libremidi/config.hpp>
 #include <libremidi/detail/observer.hpp>
+#include <libremidi/observer_configuration.hpp>
 
-#include <functional>
+#include <alsa/asoundlib.h>
+
+#include <cerrno>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
 #include <string>
 #include <string_view>
+#include <system_error>
 #include <vector>
 
 // Credits: greatly inspired from
@@ -13,9 +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
 {
@@ -27,25 +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;
@@ -91,7 +96,6 @@ struct enumerator
       : handler{self}
       , configuration{self.configuration}
   {
-
   }
 
   // 1: is an input / output
@@ -114,8 +118,9 @@ struct enumerator
     else if (status < 0 && status != -ENXIO)
     {
       handler.libremidi_handle_error(
-          configuration, "Cannot get rawmidi information: " + device_identifier(card, device, sub)
+          configuration,
-                             + " : " + snd.strerror(status));
+          "Cannot get rawmidi information: " + device_identifier(card, device, sub) + " : "
+              + snd.strerror(status));
       return status;
     }
     else
@@ -201,7 +206,8 @@ inline snd_ctl_wrapper::snd_ctl_wrapper(enumerator& self, const char* name)
   if (status < 0)
   {
     self.handler.libremidi_handle_error(
-        self.configuration, "cannot open control for card"s + name + " : " + snd.strerror(status));
+        self.configuration,
+        "cannot open control for card"s + name + " : " + snd.strerror(status));
   }
 }
 

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
@@ -200,7 +200,7 @@ 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)
     {
       libremidi_handle_error(this->configuration, "error creating eventfd.");
       return;
@@ -220,7 +220,7 @@ public:
 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();
@@ -228,12 +228,12 @@ private:
     for (;;)
     {
       // Poll
-      ssize_t err = poll(fds_.data(), fds_.size(), period);
+      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});
@@ -250,11 +250,11 @@ private:
     {
       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{};
@@ -264,8 +264,7 @@ private:
       using namespace std::literals;
 
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error starting MIDI input thread: "s + e.what());
-          "error starting MIDI input thread: "s + e.what());
       return e.code();
     }
     return stdx::error{};
@@ -282,16 +281,16 @@ private:
 
   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
 
     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
@@ -316,19 +315,21 @@ private:
   {
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
-          .fds = {this->fds_.data(), this->fds_.size()},
+          manual_poll_parameters{
-          .callback = [this](std::span<pollfd> fds) {
+              .fds = {this->fds_.data(), this->fds_.size()},
-            return do_read_events(&midi_in_impl::read_input_buffer, fds);
+              .callback = [this](std::span<pollfd> fds) {
-          }});
+        return do_read_events(&midi_in_impl::read_input_buffer, fds);
+      }});
     }
     else
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
-          .fds = {this->fds_.data(), this->fds_.size()},
+          manual_poll_parameters{
-          .callback = [this](std::span<pollfd> fds) {
+              .fds = {this->fds_.data(), this->fds_.size()},
-            return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
+              .callback = [this](std::span<pollfd> fds) {
-          }});
+        return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
+      }});
     }
   }
 
@@ -342,7 +343,7 @@ private:
 };
 }
 
-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
@@ -44,8 +44,7 @@ public:
     int status = snd.rawmidi.open(NULL, &midiport_, portname, mode);
     if (status < 0)
     {
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "cannot open device.");
-          this->configuration, "cannot open device.");
       return from_errc(status);
     }
     return stdx::error{};
@@ -87,8 +86,7 @@ public:
   {
     if (auto err = snd.rawmidi.write(midiport_, message, size); err < 0)
     {
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "cannot write message.");
-          this->configuration, "cannot write message.");
       return from_errc(err);
     }
 

include/libremidi/backends/alsa_raw/observer.hpp

@@ -6,9 +6,10 @@
 #if LIBREMIDI_HAS_UDEV
   #include <libremidi/backends/linux/helpers.hpp>
   #include <libremidi/backends/linux/udev.hpp>
-  #include <libremidi/detail/observer.hpp>
+#endif
+#include <libremidi/detail/observer.hpp>
 
-namespace libremidi::alsa_raw
+NAMESPACE_LIBREMIDI::alsa_raw
 {
 template <typename Enumerator>
 class observer_impl_base
@@ -27,28 +28,39 @@ 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
@@ -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;
@@ -90,59 +102,87 @@ 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()
@@ -151,7 +191,7 @@ private:
 
     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

@@ -1,7 +1,10 @@
 #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
 {
@@ -18,8 +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

@@ -3,7 +3,9 @@
 #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
 {

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
@@ -44,7 +44,8 @@ public:
     SND_RAWMIDI_NONBLOCK; // fixme
     if (int err = snd.ump.open(&midiport_, 0, portname, mode); err < 0)
     {
-      libremidi_handle_error(this->configuration, "alsa_raw_ump::ump::open_port: cannot open device.");
+      libremidi_handle_error(
+          this->configuration, "alsa_raw_ump::ump::open_port: cannot open device.");
       return from_errc(err);
     }
 
@@ -143,7 +144,8 @@ public:
     while ((err = snd.ump.read(this->midiport_, words, nwords * 4)) > 0)
     {
       const auto to_ns = [this] { return absolute_timestamp(); };
-      m_processing.on_bytes({words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
+      m_processing.on_bytes(
+          {words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
     }
     return err;
   }
@@ -166,7 +168,8 @@ 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);
       };
-      m_processing.on_bytes({words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
+      m_processing.on_bytes(
+          {words, words + err / 4}, m_processing.timestamp<timestamp_info>(to_ns, 0));
     }
     return err;
   }
@@ -194,7 +197,7 @@ 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)
     {
       libremidi_handle_error(this->configuration, "error creating eventfd.");
       return;
@@ -206,14 +209,14 @@ public:
   ~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();
@@ -221,12 +224,12 @@ private:
     for (;;)
     {
       // Poll
-      ssize_t err = poll(fds_.data(), fds_.size(), period);
+      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});
@@ -243,11 +246,11 @@ private:
     {
       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{};
@@ -257,8 +260,7 @@ private:
       using namespace std::literals;
 
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error starting MIDI input thread: "s + e.what());
-          "error starting MIDI input thread: "s + e.what());
       return e.code();
     }
     return stdx::error{};
@@ -275,16 +277,16 @@ private:
 
   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
 
     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
@@ -299,7 +301,7 @@ public:
   ~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;
   }
@@ -309,19 +311,21 @@ private:
   {
     if (configuration.timestamps == timestamp_mode::NoTimestamp)
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
-          .fds = {this->fds_.data(), this->fds_.size()},
+          manual_poll_parameters{
-          .callback = [this](std::span<pollfd> fds) {
+              .fds = {this->fds_.data(), this->fds_.size()},
-            return do_read_events(&midi_in_impl::read_input_buffer, fds);
+              .callback = [this](std::span<pollfd> fds) {
-          }});
+        return do_read_events(&midi_in_impl::read_input_buffer, fds);
+      }});
     }
     else
     {
-      configuration.manual_poll(manual_poll_parameters{
+      configuration.manual_poll(
-          .fds = {this->fds_.data(), this->fds_.size()},
+          manual_poll_parameters{
-          .callback = [this](std::span<pollfd> fds) {
+              .fds = {this->fds_.data(), this->fds_.size()},
-            return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
+              .callback = [this](std::span<pollfd> fds) {
-          }});
+        return do_read_events(&midi_in_impl::read_input_buffer_with_timestamps, fds);
+      }});
     }
   }
 
@@ -335,7 +339,7 @@ private:
 };
 }
 
-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

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:

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;
         }
       }
@@ -272,8 +302,7 @@ struct alsa_data
     // Make subscription
     if (int err = snd.seq.port_subscribe_malloc(&this->subscription); err < 0)
     {
-      self.libremidi_handle_error(
+      self.libremidi_handle_error(self.configuration, "ALSA error allocation port subscription.");
-          self.configuration, "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
 {
@@ -195,11 +195,6 @@ public:
     return stdx::error{};
   }
 
-  stdx::error set_client_name(std::string_view clientName) override
-  {
-    return alsa_data::set_client_name(clientName);
-  }
-
   stdx::error set_port_name(std::string_view portName) override
   {
     return alsa_data::set_port_name(portName);
@@ -212,7 +207,7 @@ public:
         .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)
     {
@@ -258,17 +253,17 @@ public:
     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;
       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;
         }
@@ -353,7 +348,7 @@ 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->libremidi_handle_error(this->configuration, "error creating eventfd.");
       return;
@@ -364,7 +359,7 @@ public:
 
   ~midi_in_alsa_threaded()
   {
-    this->close_port();
+    midi_in_alsa_threaded::close_port();
     this->client_open_ = std::errc::not_connected;
   }
 
@@ -399,7 +394,7 @@ private:
   {
     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)
@@ -415,12 +410,12 @@ private:
 
   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{};
   }
 
@@ -428,7 +423,7 @@ private:
   {
     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
@@ -439,10 +434,10 @@ private:
       if (alsa_data::snd.seq.event_input_pending(this->seq, 1) == 0)
       {
         // No data pending
-        if (poll(poll_fds, poll_fd_count, period) >= 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;
           }
@@ -450,7 +445,7 @@ private:
         continue;
       }
 
-      int res{};
+      int64_t res{};
       if constexpr (ConfigurationImpl::midi_version == 1)
       {
         res = this->process_events();
@@ -467,8 +462,8 @@ private:
     }
   }
 
-  std::thread thread{};
+  std::thread m_thread{};
-  eventfd_notifier termination_event{};
+  eventfd_notifier m_termination_event{};
 };
 
 template <typename ConfigurationBase, typename ConfigurationImpl>
@@ -487,17 +482,17 @@ public:
     using poll_params = typename ConfigurationImpl::poll_parameters_type;
     this->configuration.manual_poll(
         poll_params{.addr = this->vaddr, .callback = [this](const auto& ev) {
-                      if constexpr (ConfigurationImpl::midi_version == 1)
+      if constexpr (ConfigurationImpl::midi_version == 1)
-                        return this->process_event(ev);
+        return this->process_event(ev);
 #if __has_include(<alsa/ump.h>)
-                      else
+      else
-                        return this->process_ump_event(ev);
+        return this->process_ump_event(ev);
 #endif
-                    }});
+    }});
     return 0;
   }
 
-  ~midi_in_alsa_manual() { this->close_port(); }
+  ~midi_in_alsa_manual() { midi_in_alsa_manual::close_port(); }
 
   stdx::error open_port(const input_port& pt, std::string_view local_port_name) override
   {
@@ -530,7 +525,7 @@ public:
 };
 }
 
-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
@@ -30,7 +30,7 @@ public:
       return;
     }
 
-    if (snd.midi.event_new(this->bufferSize, &this->coder) < 0)
+    if (snd.midi.event_new(this->m_bufferSize, &this->coder) < 0)
     {
       libremidi_handle_error(this->configuration, "error initializing MIDI event parser.");
       return;
@@ -68,8 +68,9 @@ public:
 
   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)
     {
       libremidi_handle_error(this->configuration, "no MIDI output sources found!");
       return make_error_code(std::errc::no_such_device);
@@ -109,11 +110,6 @@ public:
     return stdx::error{};
   }
 
-  stdx::error set_client_name(std::string_view clientName) override
-  {
-    return alsa_data::set_client_name(clientName);
-  }
-
   stdx::error set_port_name(std::string_view portName) override
   {
     return alsa_data::set_port_name(portName);
@@ -122,9 +118,9 @@ public:
   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)
       {
@@ -146,8 +142,8 @@ 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)
       {
         libremidi_handle_warning(this->configuration, "event parsing error!");
@@ -174,6 +170,6 @@ public:
   }
 
 private:
-  uint64_t bufferSize{32};
+  uint64_t m_bufferSize{32};
 };
 }

include/libremidi/backends/alsa_seq/observer.hpp

@@ -7,20 +7,32 @@
 
 #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>
@@ -88,12 +100,69 @@ public:
     }
   }
 
-  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)
@@ -104,55 +173,57 @@ 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;
-
-    static constexpr auto virtual_port
-        = SND_SEQ_PORT_TYPE_SOFTWARE | SND_SEQ_PORT_TYPE_SYNTHESIZER;
-
-    if ((tp & SND_SEQ_PORT_TYPE_HARDWARE) && this->configuration.track_hardware)
-      ok = true;
-    else if ((tp & virtual_port) && 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()
   {
     alsa_seq::for_all_ports(
         snd, this->seq, [this](snd_seq_client_info_t& client, snd_seq_port_info_t& port) {
-          int clt = snd.seq.client_info_get_client(&client);
+      int clt = snd.seq.client_info_get_client(&client);
-          int pt = snd.seq.port_info_get_port(&port);
+      int pt = snd.seq.port_info_get_port(&port);
-          register_port(clt, pt);
+      register_port(clt, pt);
-        });
+    });
   }
 
   libremidi::API get_current_api() const noexcept override
@@ -168,12 +239,12 @@ public:
     std::vector<libremidi::input_port> ret;
     alsa_seq::for_all_ports(
         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 clt = snd.seq.client_info_get_client(&client);
-          int pt = snd.seq.port_info_get_port(&port);
+      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));
+          ret.push_back(to_port_info<true>(*p));
-        });
+    });
     return ret;
   }
 
@@ -182,12 +253,12 @@ public:
     std::vector<libremidi::output_port> ret;
     alsa_seq::for_all_ports(
         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 clt = snd.seq.client_info_get_client(&client);
-          int pt = snd.seq.port_info_get_port(&port);
+      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));
+          ret.push_back(to_port_info<false>(*p));
-        });
+    });
     return ret;
   }
 
@@ -200,13 +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));
     }
@@ -214,37 +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;
     }
@@ -263,7 +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>
@@ -275,38 +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(), period);
+        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();
@@ -317,7 +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>
@@ -329,16 +478,16 @@ 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;
+      return 0;
-                        }});
+    }});
   }
 
   ~observer_manual() { this->configuration.stop_poll(this->vaddr); }
 };
 }
 
-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

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
@@ -64,8 +64,9 @@ public:
 
   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)
     {
       libremidi_handle_error(this->configuration, "no MIDI output sources found!");
       return make_error_code(std::errc::no_such_device);
@@ -105,11 +106,6 @@ public:
     return stdx::error{};
   }
 
-  stdx::error set_client_name(std::string_view clientName) override
-  {
-    return alsa_data::set_client_name(clientName);
-  }
-
   stdx::error set_port_name(std::string_view portName) override
   {
     return alsa_data::set_port_name(portName);
@@ -133,9 +129,10 @@ public:
         libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
         return static_cast<std::errc>(-ret);
       }
-      return std::errc{0};
+      static_assert(std::errc{0} == std::errc{});
+      return std::errc{};
     };
-    segment_ump_stream(ump_stream, count, write_func, []() {});
+    segment_ump_stream(ump_stream, count, write_func, []() { });
 
     snd.seq.drain_output(this->seq);
     return stdx::error{};

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

@@ -18,7 +18,7 @@ typedef MIDIObjectRef MIDIClientRef;
 using MIDIClientRef = uint32_t;
 using MIDIObjectRef = uint32_t;
 #endif
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 
 struct coremidi_input_configuration

include/libremidi/backends/coremidi/error_domain.hpp

@@ -3,7 +3,7 @@
 
 #include <CoreMIDI/CoreMIDI.h>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct coremidi_error_domain : public stdx::error_domain
 {

include/libremidi/backends/coremidi/helpers.hpp

@@ -1,9 +1,9 @@
 #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 <libremidi/backends/coremidi/error_domain.hpp>
 
 #include <CoreMIDI/CoreMIDI.h>
 #include <CoreServices/CoreServices.h>
@@ -21,13 +21,12 @@
   #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;
   if (MIDIObjectGetStringProperty(object, property, &res) || !res)
@@ -39,14 +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)};
 }
@@ -71,20 +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());
   }
@@ -101,7 +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());
     }
@@ -112,7 +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());
 
@@ -218,22 +219,19 @@ locate_object(auto& self, const port_information& info, MIDIObjectType requested
   auto ret = MIDIObjectFindByUniqueID(uid, &object, &type);
   if (ret != noErr)
   {
-    self.libremidi_handle_error(
+    self.libremidi_handle_error(self.configuration, "cannot find port: " + info.port_name);
-        self.configuration, "cannot find port: " + info.port_name);
     return 0;
   }
 
   if (type != requested_type || object == 0)
   {
     self.libremidi_handle_error(
-        self.configuration, "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.

include/libremidi/backends/coremidi/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_core final
     : public midi1::in_api
@@ -25,8 +25,7 @@ public:
     if (auto result = init_client(configuration); result != noErr)
     {
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "error creating MIDI client object: " + std::to_string(result));
       client_open_ = from_osstatus(result);
       return;
     }
@@ -64,8 +63,7 @@ public:
     {
       close_client(*this);
       libremidi_handle_error(
-          this->configuration, "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);
     }
 
@@ -74,8 +72,7 @@ public:
     {
       MIDIPortDispose(port);
       close_client(*this);
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error connecting macOS MIDI input port.");
-          this->configuration, "error connecting macOS MIDI input port.");
       return from_osstatus(result);
     }
 
@@ -105,10 +102,7 @@ public:
     return stdx::error{};
   }
 
-  stdx::error close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    return coremidi_data::close_port();
-  }
 
   timestamp absolute_timestamp() const noexcept override
   {

include/libremidi/backends/coremidi/midi_out.hpp

@@ -3,7 +3,7 @@
 #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
@@ -24,8 +24,7 @@ public:
     if (auto result = init_client(configuration); result != noErr)
     {
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "error creating MIDI client object: " + std::to_string(result));
       client_open_ = from_osstatus(result);
       return;
     }
@@ -60,8 +59,7 @@ public:
     if (result != noErr)
     {
       close_client(*this);
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error creating macOS MIDI output port.");
-          this->configuration, "error creating macOS MIDI output port.");
       return from_osstatus(result);
     }
 
@@ -80,9 +78,7 @@ public:
 
     if (result != noErr)
     {
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error creating macOS virtual MIDI source.");
-          this->configuration,
-          "error creating macOS virtual MIDI source.");
 
       return from_osstatus(result);
     }
@@ -92,10 +88,7 @@ public:
     return stdx::error{};
   }
 
-  stdx::error close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    return coremidi_data::close_port();
-  }
 
   stdx::error send_message(const unsigned char* message, size_t size) override
   {
@@ -118,8 +111,8 @@ public:
     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;
@@ -137,8 +130,7 @@ public:
 
       if (!packet)
       {
-        libremidi_handle_error(
+        libremidi_handle_error(this->configuration, "could not allocate packet list");
-            this->configuration, "could not allocate packet list");
 
         return std::errc::message_size;
       }
@@ -163,9 +155,7 @@ public:
         auto result = MIDISend(this->port, this->destinationId, packetList);
         if (result != noErr)
         {
-          libremidi_handle_warning(
+          libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-              this->configuration,
-              "error sending MIDI message to port.");
           return std::errc::io_error;
         }
       }

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";
@@ -32,15 +36,13 @@ public:
     auto result = MIDIClientCreate(
         toCFString(configuration.client_name).get(),
         +[](const MIDINotification* message, void* ctx) {
-          ((observer_core*)ctx)->notify(message);
+      ((observer_core*)ctx)->notify(message);
-        },
+    }, this, &client);
-        this, &client);
 
     if (result != noErr)
     {
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "error creating MIDI client object: " + std::to_string(result));
       return;
     }
 
@@ -78,13 +80,56 @@ public:
     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

@@ -3,7 +3,9 @@
 #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
 {
@@ -14,8 +16,8 @@ struct backend
   using midi_out_configuration = coremidi_ump::output_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

@@ -1,7 +1,7 @@
 #pragma once
 #include <libremidi/backends/coremidi/config.hpp>
 
-namespace libremidi::coremidi_ump
+NAMESPACE_LIBREMIDI::coremidi_ump
 {
 struct input_configuration
 {

include/libremidi/backends/coremidi_ump/midi_in.hpp

@@ -4,7 +4,7 @@
 #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
@@ -26,8 +26,7 @@ public:
     if (auto result = init_client(configuration); result != noErr)
     {
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "error creating MIDI client object: " + std::to_string(result));
       client_open_ = from_osstatus(result);
       return;
     }
@@ -69,8 +68,7 @@ public:
     {
       close_client(*this);
       libremidi_handle_error(
-          this->configuration, "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);
     }
 
@@ -79,8 +77,7 @@ public:
     {
       MIDIPortDispose(port);
       close_client(*this);
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error connecting macOS MIDI input port.");
-          this->configuration, "error connecting macOS MIDI input port.");
       return from_osstatus(result);
     }
 
@@ -113,10 +110,7 @@ public:
     return stdx::error{};
   }
 
-  stdx::error close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    return coremidi_data::close_port();
-  }
 
   timestamp absolute_timestamp() const noexcept override
   {

include/libremidi/backends/coremidi_ump/midi_out.hpp

@@ -5,7 +5,7 @@
 #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
@@ -27,8 +27,7 @@ public:
     if (auto result = init_client(configuration); result != noErr)
     {
       libremidi_handle_error(
-          this->configuration,
+          this->configuration, "error creating MIDI client object: " + std::to_string(result));
-          "error creating MIDI client object: " + std::to_string(result));
       client_open_ = from_osstatus(result);
       return;
     }
@@ -63,8 +62,7 @@ public:
     if (result != noErr)
     {
       close_client(*this);
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error creating macOS MIDI output port.");
-          this->configuration, "error creating macOS MIDI output port.");
       return from_osstatus(result);
     }
 
@@ -84,9 +82,7 @@ public:
     if (result != noErr)
     {
       this->endpoint = 0;
-      libremidi_handle_error(
+      libremidi_handle_error(this->configuration, "error creating macOS virtual MIDI source.");
-          this->configuration,
-          "error creating macOS virtual MIDI source.");
 
       return from_osstatus(result);
     }
@@ -94,10 +90,7 @@ public:
     return stdx::error{};
   }
 
-  stdx::error close_port() override
+  stdx::error close_port() override { return coremidi_data::close_port(); }
-  {
-    return coremidi_data::close_port();
-  }
 
   stdx::error send_ump(const uint32_t* ump_stream, std::size_t count) override
   {
@@ -142,9 +135,7 @@ public:
       auto result = MIDISendEventList(this->port, this->destinationId, eventList);
       if (result != noErr)
       {
-        libremidi_handle_warning(
+        libremidi_handle_warning(this->configuration, "error sending MIDI message to port.");
-            this->configuration,
-            "error sending MIDI message to port.");
         return std::errc::io_error;
       }
     }

include/libremidi/backends/coremidi_ump/observer.hpp

@@ -1,17 +1,20 @@
 #pragma once
-#include <libremidi/backends/coremidi_ump/config.hpp>
 #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
 {
 public:
-  explicit observer_impl(libremidi::observer_configuration&& conf, coremidi_ump::observer_configuration&& apiconf)
+  explicit observer_impl(
-      : observer_core{std::move(conf), coremidi_observer_configuration{apiconf.client_name, apiconf.on_create_context}}
+      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
 {
@@ -23,11 +25,12 @@ class midi_in_dummy final
     , public error_handler
 {
 public:
-  explicit midi_in_dummy(const input_configuration& configuration, std::any)
+  explicit midi_in_dummy(const input_configuration& configuration, const input_api_configuration&)
   {
     libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
-  explicit midi_in_dummy(const ump_input_configuration& configuration, std::any)
+  explicit midi_in_dummy(
+      const ump_input_configuration& configuration, const input_api_configuration&)
   {
     libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
@@ -37,19 +40,9 @@ public:
   {
     return stdx::error{};
   }
-  stdx::error open_virtual_port(std::string_view /*portName*/) override
+  stdx::error open_virtual_port(std::string_view /*portName*/) override { return stdx::error{}; }
-  {
-    return stdx::error{};
-  }
   stdx::error close_port() override { return stdx::error{}; }
-  stdx::error set_client_name(std::string_view /*clientName*/) override
+  stdx::error set_port_name(std::string_view /*portName*/) override { return stdx::error{}; }
-  {
-    return stdx::error{};
-  }
-  stdx::error set_port_name(std::string_view /*portName*/) override
-  {
-    return stdx::error{};
-  }
   timestamp absolute_timestamp() const noexcept override { return 0; }
 };
 
@@ -58,7 +51,8 @@ class midi_out_dummy final
     , public error_handler
 {
 public:
-  explicit midi_out_dummy(const output_configuration& configuration, std::any)
+  explicit midi_out_dummy(
+      const output_configuration& configuration, const output_api_configuration&)
   {
     libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
@@ -68,20 +62,10 @@ public:
   {
     return stdx::error{};
   }
-  stdx::error open_virtual_port(std::string_view /*portName*/) override
+  stdx::error open_virtual_port(std::string_view /*portName*/) override { return stdx::error{}; }
-  {
-    return stdx::error{};
-  }
 
   stdx::error close_port() override { return stdx::error{}; }
-  stdx::error set_client_name(std::string_view /*clientName*/) override
+  stdx::error set_port_name(std::string_view /*portName*/) override { return stdx::error{}; }
-  {
-    return stdx::error{};
-  }
-  stdx::error set_port_name(std::string_view /*portName*/) override
-  {
-    return stdx::error{};
-  }
   stdx::error send_message(const unsigned char* /*message*/, size_t /*size*/) override
   {
     return stdx::error{};
@@ -97,8 +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(                            \
         {                                         \
@@ -206,6 +215,9 @@ public:
 
   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

@@ -5,7 +5,7 @@
 
   #include <chrono>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 LIBREMIDI_INLINE midi_in_emscripten::midi_in_emscripten(
     input_configuration&& conf, emscripten_input_configuration&& apiconf)
@@ -32,13 +32,12 @@ LIBREMIDI_INLINE stdx::error midi_in_emscripten::open_port(int portNumber, std::
 
   if (portNumber < 0 || portNumber >= midi.input_count())
   {
-    libremidi_handle_error(
+    libremidi_handle_error(this->configuration, "no MIDI output sources found.");
-        this->configuration, "no MIDI output sources found.");
     return std::errc::invalid_argument;
   }
 
   midi.open_input(portNumber, *this);
-  portNumber_ = portNumber;
+  m_portNumber = portNumber;
   return stdx::error{};
 }
 
@@ -52,7 +51,7 @@ LIBREMIDI_INLINE stdx::error midi_in_emscripten::close_port()
 {
   auto& midi = webmidi_helpers::midi_access_emscripten::instance();
 
-  midi.close_input(portNumber_, *this);
+  midi.close_input(m_portNumber, *this);
 
   return stdx::error{};
 }

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
@@ -31,7 +31,7 @@ public:
   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

@@ -2,7 +2,7 @@
   #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)
@@ -29,34 +29,36 @@ LIBREMIDI_INLINE stdx::error midi_out_emscripten::open_port(int portNumber, std:
 
   if (portNumber >= midi.output_count())
   {
-    libremidi_handle_error(
+    libremidi_handle_error(this->configuration, "no MIDI output sources found.");
-        this->configuration, "no MIDI output sources found.");
     return std::errc::invalid_argument;
   }
 
-  portNumber_ = portNumber;
+  m_portNumber = portNumber;
   return stdx::error{};
 }
 
-LIBREMIDI_INLINE stdx::error 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 stdx::error midi_out_emscripten::close_port() { 
+LIBREMIDI_INLINE stdx::error midi_out_emscripten::close_port()
+{
   return stdx::error{};
 }
 
-LIBREMIDI_INLINE stdx::error midi_out_emscripten::send_message(const unsigned char* message, size_t size)
+LIBREMIDI_INLINE stdx::error
+midi_out_emscripten::send_message(const unsigned char* message, size_t size)
 {
-  if (portNumber_ < 0)
+  if (m_portNumber < 0)
     libremidi_handle_error(
         this->configuration,
         "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{};
 }
 }

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
@@ -28,6 +28,6 @@ public:
   stdx::error 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

@@ -11,7 +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

include/libremidi/backends/jack/error_domain.hpp

@@ -11,7 +11,7 @@
   #include <jack/ringbuffer.h>
 #endif
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct jack_error_domain : public stdx::error_domain
 {
@@ -34,36 +34,36 @@ public:
   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{})
+    if (status == jack_status_t{})
       return "Success";
 
-    if(status & JackInvalidOption)
+    if (status & JackInvalidOption)
       return "The operation contained an invalid or unsupported option";
-    if(status & JackServerFailed)
+    if (status & JackServerFailed)
       return "Unable to connect to the JACK server";
-    if(status & JackServerError)
+    if (status & JackServerError)
       return "Communication error with the JACK server";
-    if(status & JackNoSuchClient)
+    if (status & JackNoSuchClient)
       return "Requested client does not exist";
-    if(status & JackLoadFailure)
+    if (status & JackLoadFailure)
       return "Unable to load internal client";
-    if(status & JackInitFailure)
+    if (status & JackInitFailure)
       return "Unable to initialize client";
-    if(status & JackShmFailure)
+    if (status & JackShmFailure)
       return "Unable to access shared memory";
-    if(status & JackVersionError)
+    if (status & JackVersionError)
       return "Client's protocol version does not match";
-    if(status & JackBackendError)
+    if (status & JackBackendError)
       return "Backend error";
-    if(status & JackClientZombie)
+    if (status & JackClientZombie)
       return "Client zombified failure";
-    if(status & JackFailure)
+    if (status & JackFailure)
       return "Failure";
-    if(status & JackNameNotUnique)
+    if (status & JackNameNotUnique)
       return "The desired client name was not unique";
 
     // Can't happen in libremidi as we set JackNoStartServer
-    if(status & JackServerStarted)
+    if (status & JackServerStarted)
       return "Server was started";
 
     return "Unknown JACK status code";

include/libremidi/backends/jack/helpers.hpp

@@ -5,9 +5,11 @@
 #include <libremidi/detail/semaphore.hpp>
 
 #include <atomic>
-#include <semaphore>
+#include <cstdint>
+#include <cstring>
+#include <memory>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 struct jack_client
 {
@@ -39,31 +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 {};
@@ -73,7 +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++;
     }
 
@@ -131,13 +138,13 @@ struct jack_helpers : jack_client
       configuration.set_process_func(
           {.token = this_instance,
            .callback = [&self, p = std::weak_ptr{this->port.impl}](jack_nframes_t nf) -> int {
-             if (auto pt = p.lock())
+        if (auto pt = p.lock())
-               if (auto ppt = pt->load())
+          if (pt->load())
-                 self.process(nf);
+            self.process(nf);
 
-             self.thread_lock.check_client_released();
+        self.thread_lock.check_client_released();
-             return 0;
+        return 0;
-           }});
+      }});
 
       this->client = configuration.context;
       return jack_status_t{};
@@ -149,26 +156,25 @@ struct jack_helpers : jack_client
           = jack_client_open(configuration.client_name.c_str(), JackNoStartServer, &status);
       if (this->client != nullptr)
       {
-        if(status & JackNameNotUnique) {
+        if (status & JackNameNotUnique)
-          self.libremidi_handle_warning(self.configuration, "JACK client with the same name already exists, renamed.");
+        {
+          self.libremidi_handle_warning(
+              self.configuration, "JACK client with the same name already exists, renamed.");
         }
 
-        jack_set_process_callback(
+        jack_set_process_callback(this->client, +[](jack_nframes_t nf, void* ctx) -> int {
-            this->client,
+          auto& self = *static_cast<Self*>(ctx);
-            +[](jack_nframes_t nf, void* ctx) -> int {
+          jack_port_t* port = self.port;
-              auto& self = *static_cast<Self*>(ctx);
-              jack_port_t* port = self.port;
 
-              // Is port created?
+          // Is port created?
-              if (port == nullptr)
+          if (port == nullptr)
-                return 0;
+            return 0;
 
-              self.process(nf);
+          self.process(nf);
 
-              self.thread_lock.check_client_released();
+          self.thread_lock.check_client_released();
-              return 0;
+          return 0;
-            },
+        }, &self);
-            &self);
         jack_activate(this->client);
       }
       return status;
@@ -192,8 +198,8 @@ struct jack_helpers : jack_client
     self.client_open_ = std::errc::not_connected;
   }
 
-  stdx::error
+  stdx::error create_local_port(
-  create_local_port(const auto& self, std::string_view portName, JackPortFlags flags)
+      const auto& self, std::string_view portName, const char* type, JackPortFlags flags)
   {
     // full name: "client_name:port_name\0"
     if (portName.empty())
@@ -202,15 +208,13 @@ struct jack_helpers : jack_client
     if (self.configuration.client_name.size() + portName.size() + 2u
         >= static_cast<size_t>(jack_port_name_size()))
     {
-      self.libremidi_handle_error(
+      self.libremidi_handle_error(self.configuration, "port name length limit exceeded");
-          self.configuration, "port name length limit exceeded");
       return std::errc::invalid_argument;
     }
 
     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)
@@ -238,4 +242,77 @@ struct jack_helpers : jack_client
     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

@@ -4,13 +4,12 @@
 #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:
@@ -46,15 +45,16 @@ public:
 
   stdx::error open_port(const input_port& port, std::string_view portName) override
   {
-    if (auto err = create_local_port(*this, portName, JackPortIsInput); err != stdx::error{})
+    if (auto err = create_local_port(*this, portName, port_type, JackPortIsInput);
+        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 + " -> "
+          configuration,
-                             + jack_port_name(this->port));
+          "could not connect to port: " + port.port_name + " -> " + jack_port_name(this->port));
       return from_errc(err);
     }
     return stdx::error{};
@@ -62,7 +62,7 @@ public:
 
   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);
   }
 
   stdx::error close_port() override { return do_close_port(); }
@@ -96,8 +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

@@ -3,76 +3,12 @@
 #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);
-  }
-
-  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
-};
-
 class midi_out_jack
     : public midi1::out_api
     , public jack_helpers
+    , public jack_midi1
     , public error_handler
 {
 public:
@@ -94,15 +30,15 @@ public:
 
   stdx::error open_port(const output_port& port, std::string_view portName) override
   {
-    if (auto err = create_local_port(*this, portName, JackPortIsOutput); err != stdx::error{})
+    if (auto err = create_local_port(*this, portName, port_type, JackPortIsOutput);
+        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(
+      libremidi_handle_error(configuration, "could not connect to port" + port.port_name);
-          configuration, "could not connect to port" + port.port_name);
       return from_errc(err);
     }
 
@@ -111,7 +47,7 @@ public:
 
   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);
   }
 
   stdx::error close_port() override { return do_close_port(); }
@@ -128,7 +64,7 @@ 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 (!this->client)
@@ -150,7 +86,7 @@ public:
 
   stdx::error send_message(const unsigned char* message, std::size_t size) override
   {
-    return queue.write(message, size);
+    return m_queue.write(message, size);
   }
 
   int process(jack_nframes_t nframes)
@@ -158,13 +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
@@ -230,7 +166,7 @@ public:
 };
 }
 
-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:
@@ -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);
       }
     }
@@ -172,39 +177,37 @@ 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,
+      auto& self = *(observer_jack*)arg;
-        +[](jack_port_id_t p, int r, void* arg) {
+      if (auto port = jack_port_by_id(self.client, p))
-          auto& self = *(observer_jack*)arg;
+      {
-          if (auto port = jack_port_by_id(self.client, p))
+        self.on_port_callback(port, r != 0);
-          {
+      }
-            self.on_port_callback(port, r != 0);
+    }, this);
-          }
-        },
-        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);
+      const auto& self = *static_cast<observer_jack*>(arg);
 
-          auto port = jack_port_by_id(self.client, p);
+      auto port = jack_port_by_id(self.client, p);
-          if (!port)
+      if (!port)
-            return;
+        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,
+      ((shared_handler*)ctx)->jack_callback(cnt);
-        +[](jack_nframes_t cnt, void* ctx) -> int {
+      return 0;
-          ((shared_handler*)ctx)->jack_callback(cnt);
+    }, this);
-          return 0;
-        },
-        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

@@ -2,7 +2,9 @@
 #include <libremidi/backends/dummy.hpp>
 #include <libremidi/backends/keyboard/midi_in.hpp>
 
-namespace libremidi
+#include <string_view>
+
+NAMESPACE_LIBREMIDI
 {
 struct kbd_backend
 {
@@ -13,8 +15,8 @@ struct kbd_backend
   using midi_out_configuration = dummy_configuration;
   using midi_observer_configuration = dummy_configuration;
   static const constexpr auto API = libremidi::API::KEYBOARD;
-  static const constexpr auto name = "keyboard";
+  static const constexpr std::string_view name = "keyboard";
-  static const constexpr auto display_name = "Computer keyboard";
+  static const constexpr std::string_view display_name = "Computer keyboard";
 
   static inline bool available() noexcept { return true; }
 };

include/libremidi/backends/keyboard/config.hpp

@@ -4,8 +4,130 @@
 #include <functional>
 #include <map>
 
-namespace libremidi
+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
@@ -13,80 +135,20 @@ namespace libremidi
  */
 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
-      = [](scancode_callback, scancode_callback) {};
+      = [](const scancode_callback&, const scancode_callback&) { };
 
-  enum kbd_event
+  std::map<int, int> scancode_map
-  {
+#if defined(__APPLE__)
-    NOTE_0 = 0x0,         // C
+      = scancode_map_macos()
-    VEL_0 = NOTE_0 + 128, // Set velocity to 0
+#else
-    OCT_0 = VEL_0 + 128,  // Set octave to 0
+      = scancode_map_linux()
-    OCTAVE_PLUS = OCT_0 + 128,
+#endif
-    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
-  // Use: https://kbdlayout.info/KBDUSX/scancodes
-  std::map<int, int> scancode_map{
-      { 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}, 
-  };
-  // clang-format on
 };
-
 }

include/libremidi/backends/keyboard/midi_in.hpp

@@ -5,7 +5,7 @@
 #include <chrono>
 #include <unordered_map>
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 class midi_in_kbd final
     : public midi1::in_api
@@ -22,22 +22,22 @@ public:
   explicit midi_in_kbd(input_configuration&& conf, kbd_input_configuration&& apiconf)
       : configuration{std::move(conf), std::move(apiconf)}
   {
-    configuration.set_input_scancode_callbacks(
-        [this](int v) { on_keypress(v); }, [this](int v) { on_keyrelease(v); });
   }
 
   ~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 { return stdx::error{}; }
+  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); });
 
-  stdx::error open_virtual_port(std::string_view) override { return stdx::error{}; }
+    return stdx::error{};
+  }
 
   stdx::error close_port() override { return stdx::error{}; }
 
-  stdx::error set_port_name(std::string_view) override { return stdx::error{}; }
-
   timestamp absolute_timestamp() const noexcept override
   {
     return std::chrono::steady_clock::now().time_since_epoch().count();
@@ -45,7 +45,7 @@ public:
 
   void on_keypress(int scancode)
   {
-    using kevent = kbd_input_configuration::kbd_event;
+    using kevent = libremidi::kbd_event;
 
     auto it = configuration.scancode_map.find(scancode);
     if (it == configuration.scancode_map.end())
@@ -88,7 +88,7 @@ public:
 
   void on_keyrelease(int scancode)
   {
-    using kevent = kbd_input_configuration::kbd_event;
+    using kevent = libremidi::kbd_event;
 
     auto it = configuration.scancode_map.find(scancode);
     if (it == configuration.scancode_map.end())

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
@@ -241,6 +245,7 @@ struct libasound
       LIBREMIDI_SYMBOL_INIT(snd_seq, client_id)
       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_card)
       LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_set_client)
       LIBREMIDI_SYMBOL_INIT(snd_seq, client_info_sizeof)
       LIBREMIDI_SYMBOL_INIT(snd_seq, close)
@@ -277,6 +282,7 @@ struct libasound
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_info_sizeof)
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_free)
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_malloc)
+      LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_sizeof)
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_dest)
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_sender)
       LIBREMIDI_SYMBOL_INIT(snd_seq, port_subscribe_set_time_real)
@@ -291,6 +297,12 @@ struct libasound
       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};
@@ -298,6 +310,7 @@ struct libasound
     LIBREMIDI_SYMBOL_DEF(snd_seq, client_id)
     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_card)
     LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_set_client)
     LIBREMIDI_SYMBOL_DEF(snd_seq, client_info_sizeof)
     LIBREMIDI_SYMBOL_DEF(snd_seq, close)
@@ -334,6 +347,7 @@ struct libasound
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_info_sizeof)
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_free)
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_malloc)
+    LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_sizeof)
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_dest)
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_sender)
     LIBREMIDI_SYMBOL_DEF(snd_seq, port_subscribe_set_time_real)
@@ -350,6 +364,12 @@ struct libasound
     LIBREMIDI_SYMBOL_DEF(snd_seq, subscribe_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
     {
@@ -360,7 +380,6 @@ 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_output)
         LIBREMIDI_SYMBOL_INIT(snd_seq_ump, event_output_direct)
@@ -368,10 +387,10 @@ struct libasound
 
       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_output)
       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, close)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_get_name)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, endpoint_info_sizeof)
       LIBREMIDI_SYMBOL_INIT(snd_ump, open)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, close)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_count)
-      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_revents)
       LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi)
       LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params)
       LIBREMIDI_SYMBOL_INIT(snd_ump, rawmidi_params_current)
       LIBREMIDI_SYMBOL_INIT(snd_ump, read)
       LIBREMIDI_SYMBOL_INIT(snd_ump, tread)
       LIBREMIDI_SYMBOL_INIT(snd_ump, write)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_count)
+      LIBREMIDI_SYMBOL_INIT(snd_ump, poll_descriptors_revents)
+
+      // Endpoint info functions
+      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, endpoint_info_get_name)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, endpoint_info_sizeof)
     LIBREMIDI_SYMBOL_DEF(snd_ump, open)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, close)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_count)
-    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_revents)
     LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi)
     LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params)
     LIBREMIDI_SYMBOL_DEF(snd_ump, rawmidi_params_current)
     LIBREMIDI_SYMBOL_DEF(snd_ump, read)
     LIBREMIDI_SYMBOL_DEF(snd_ump, tread)
     LIBREMIDI_SYMBOL_DEF(snd_ump, write)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_count)
+    LIBREMIDI_SYMBOL_DEF(snd_ump, poll_descriptors_revents)
+
+    // 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
@@ -25,12 +27,28 @@ struct libudev
 
     LIBREMIDI_SYMBOL_INIT(udev, device_get_action)
     LIBREMIDI_SYMBOL_INIT(udev, device_get_subsystem)
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_property_value)
+    LIBREMIDI_SYMBOL_INIT(udev, device_new_from_syspath)
+    LIBREMIDI_SYMBOL_INIT(udev, device_get_parent_with_subsystem_devtype)
     LIBREMIDI_SYMBOL_INIT(udev, device_unref)
+
     LIBREMIDI_SYMBOL_INIT(udev, monitor_enable_receiving)
     LIBREMIDI_SYMBOL_INIT(udev, monitor_get_fd)
     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)
   }
@@ -46,12 +64,28 @@ struct libudev
 
   LIBREMIDI_SYMBOL_DEF(udev, device_get_action)
   LIBREMIDI_SYMBOL_DEF(udev, device_get_subsystem)
+  LIBREMIDI_SYMBOL_DEF(udev, device_new_from_syspath)
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_property_value)
+  LIBREMIDI_SYMBOL_DEF(udev, device_get_parent_with_subsystem_devtype)
   LIBREMIDI_SYMBOL_DEF(udev, device_unref)
+
   LIBREMIDI_SYMBOL_DEF(udev, monitor_enable_receiving)
   LIBREMIDI_SYMBOL_DEF(udev, monitor_get_fd)
   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)
 };
@@ -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

@@ -2,12 +2,15 @@
 #include <libremidi/config.hpp>
 
 #include <string>
+
+#if !defined(BOOST_ASIO_IO_CONTEXT_HPP)
 namespace boost::asio
 {
 struct io_context;
 }
+#endif
 
-namespace libremidi::net
+NAMESPACE_LIBREMIDI::net
 {
 enum class protocol
 {
@@ -46,7 +49,7 @@ struct dgram_observer_configuration
 
 }
 
-namespace libremidi::net_ump
+NAMESPACE_LIBREMIDI::net_ump
 {
 enum class protocol
 {

include/libremidi/backends/net/helpers.hpp

@@ -35,38 +35,41 @@ public:
 */
 }
 
-namespace libremidi
+NAMESPACE_LIBREMIDI
 {
 template <typename T>
 struct optionally_owned
 {
 public:
   explicit optionally_owned(T* maybe_existing)
-      : storage{.ref = maybe_existing}
+      : m_storage{.ref = maybe_existing}
   {
-    if (storage.ref)
+    if (m_storage.ref)
     {
-      ownership = unowned;
+      m_ownership = unowned;
       return;
     }
     else
     {
-      std::destroy_at(&storage.ref);
+      std::destroy_at(&m_storage.ref);
-      std::construct_at<T>(reinterpret_cast<T*>(storage.object));
+      std::construct_at<T>(reinterpret_cast<T*>(m_storage.object));
-      ownership = owned;
+      m_ownership = owned;
     }
   }
 
   ~optionally_owned()
   {
     if (is_owned())
-      std::destroy_at(reinterpret_cast<T*>(storage.object));
+      std::destroy_at(reinterpret_cast<T*>(m_storage.object));
   }
 
-  T& get() noexcept { return *(is_owned() ? reinterpret_cast<T*>(&storage.object) : storage.ref); }
+  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*>(&storage.object) : storage.ref);
+    return *(is_owned() ? reinterpret_cast<T*>(&m_storage.object) : m_storage.ref);
   }
 
   optionally_owned(const optionally_owned&) = delete;
@@ -74,18 +77,18 @@ public:
   optionally_owned& operator=(const optionally_owned&) = delete;
   optionally_owned& operator=(optionally_owned&&) noexcept = delete;
 
-  bool is_owned() const noexcept { return ownership == owned; }
+  bool is_owned() const noexcept { return m_ownership == owned; }
 
 private:
   union
   {
     alignas(T) unsigned char object[sizeof(T)];
     T* ref;
-  } storage;
+  } m_storage;
   enum
   {
     owned,
     unowned
-  } ownership{};
+  } m_ownership{};
 };
 }

include/libremidi/backends/net/midi_in.hpp

@@ -4,7 +4,8 @@
 #include <libremidi/detail/midi_in.hpp>
 #include <libremidi/detail/midi_stream_decoder.hpp>
 
-namespace libremidi
+#include <thread>
+NAMESPACE_LIBREMIDI
 {
 template <typename Impl, typename F>
 struct osc_parser
@@ -114,7 +115,7 @@ struct osc_parser
 
 }
 
-namespace libremidi::net
+NAMESPACE_LIBREMIDI::net
 {
 
 struct osc_parser_midi1
@@ -219,8 +220,6 @@ public:
     return {};
   }
 
-  stdx::error set_port_name(std::string_view) override { return stdx::error{}; }
-
   timestamp absolute_timestamp() const noexcept override
   {
     return std::chrono::steady_clock::now().time_since_epoch().count();
@@ -265,7 +264,7 @@ public:
 };
 }
 
-namespace libremidi::net_ump
+NAMESPACE_LIBREMIDI::net_ump
 {
 struct osc_parser_midi2
 {
@@ -394,8 +393,6 @@ public:
     return {};
   }
 
-  stdx::error set_port_name(std::string_view) override { return stdx::error{}; }
-
   timestamp absolute_timestamp() const noexcept override
   {
     return std::chrono::steady_clock::now().time_since_epoch().count();

include/libremidi/backends/net/midi_out.hpp

@@ -8,7 +8,7 @@
 #include <boost/asio/ip/udp.hpp>
 #include <boost/endian.hpp>
 
-namespace libremidi::net
+NAMESPACE_LIBREMIDI::net
 {
 
 struct osc_midi1_packet
@@ -146,7 +146,7 @@ public:
 
 }
 
-namespace libremidi::net_ump
+NAMESPACE_LIBREMIDI::net_ump
 {
 struct osc_midi2_packet
 {

include/libremidi/backends/net/observer.hpp

@@ -1,13 +1,13 @@
 #pragma once
 #include <libremidi/backends/dummy.hpp>
 
-namespace libremidi::net
+NAMESPACE_LIBREMIDI::net
 {
 using net_observer_configuration = libremidi::dummy_configuration;
 using observer = libremidi::observer_dummy;
 }
 
-namespace libremidi::net_ump
+NAMESPACE_LIBREMIDI::net_ump
 {
 using net_observer_configuration = libremidi::dummy_configuration;
 using observer = libremidi::observer_dummy;

include/libremidi/backends/network.hpp

@@ -5,7 +5,9 @@
 #include <libremidi/backends/net/midi_out.hpp>
 #include <libremidi/backends/net/observer.hpp>
 
-namespace libremidi::net
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::net
 {
 struct backend
 {
@@ -16,8 +18,8 @@ struct backend
   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 auto name = "network";
+  static const constexpr std::string_view name = "network";
-  static const constexpr auto display_name = "Network";
+  static const constexpr std::string_view display_name = "Network";
 
   static inline bool available() noexcept { return true; }
 };

include/libremidi/backends/network_ump.hpp

@@ -4,7 +4,9 @@
 #include <libremidi/backends/net/midi_out.hpp>
 #include <libremidi/backends/net/observer.hpp>
 
-namespace libremidi::net_ump
+#include <string_view>
+
+NAMESPACE_LIBREMIDI::net_ump
 {
 struct backend
 {
@@ -15,8 +17,8 @@ struct backend
   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 auto name = "network (UMP)";
+  static const constexpr std::string_view name = "network (UMP)";
-  static const constexpr auto display_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

include/libremidi/backends/pipewire/context.hpp

@@ -18,13 +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>;
@@ -79,11 +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)
     {
@@ -123,7 +124,7 @@ 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);
@@ -187,13 +188,13 @@ struct pipewire_context
       pipewire_context& self = *(pipewire_context*)object;
       if (strcmp(type, PW_TYPE_INTERFACE_Port) == 0)
         self.register_port(id, type);
-        },
+    },
         .global_remove =
             [](void* object, uint32_t id) {
       pipewire_context& self = *(pipewire_context*)object;
       self.unregister_port(id);
-        },
+    },
-        };
+    };
 
     // Start listening
     pw_registry_add_listener(this->registry, &this->registry_listener, &registry_events, this);
@@ -244,8 +245,8 @@ struct pipewire_context
     // Remove from the listeners
     auto it
         = std::find_if(port_listener.begin(), port_listener.end(), [&](const listened_port& l) {
-            return l.id == id;
+      return l.id == id;
-          });
+    });
     if (it != port_listener.end())
     {
       pw.proxy_destroy((pw_proxy*)it->port);
@@ -266,14 +267,14 @@ struct pipewire_context
     static constexpr struct pw_core_events core_events = {
         .version = PW_VERSION_CORE_EVENTS,
         .done =
-        [](void* object, uint32_t id, int seq) {
+            [](void* object, uint32_t id, int seq) {
       auto& self = *(pipewire_context*)object;
-      if(id == PW_ID_CORE && seq == self.pending)
+      if (id == PW_ID_CORE && seq == self.pending)
       {
         self.done = 1;
         libpipewire::instance().main_loop_quit(self.main_loop);
       }
-        },
+    },
     };
 
     spa_zero(core_listener);
@@ -287,7 +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,
@@ -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}
   {
   }
@@ -498,7 +503,8 @@ struct pipewire_filter
       pw.filter_destroy(this->filter);
   }
 
-  stdx::error 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(
@@ -507,7 +513,7 @@ 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);
@@ -517,7 +523,7 @@ struct pipewire_filter
     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;

include/libremidi/backends/pipewire/helpers.hpp

@@ -9,11 +9,14 @@
 #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
 {
@@ -66,14 +69,14 @@ struct pipewire_helpers
     {
       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())
+        if (auto pt = p.lock())
-              self.process(nf);
+          self.process(nf);
 
-            self.thread_lock.check_client_released();
+        self.thread_lock.check_client_released();
-          }};
+      }};
       configuration.set_process_func(cbs);
     }
     else
@@ -84,10 +87,10 @@ struct pipewire_helpers
       static constexpr struct pw_filter_events filter_events
           = {.version = PW_VERSION_FILTER_EVENTS,
              .process = +[](void* _data, struct spa_io_position* position) -> void {
-               // FIXME likely we need the thread_lock check here too
+        // FIXME likely we need the thread_lock check here too
-               Self& self = *static_cast<Self*>(_data);
+        Self& self = *static_cast<Self*>(_data);
-               self.process(position);
+        self.process(position);
-             }};
+      }};
 #pragma GCC diagnostic pop
 
       this->filter->create_filter(self.configuration.client_name, filter_events, &self);
@@ -197,7 +200,8 @@ struct pipewire_helpers
   }
 
   template <typename Self>
-  stdx::error 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);
@@ -207,7 +211,7 @@ struct pipewire_helpers
 
     if (!this->filter->port)
     {
-      auto ret = this->filter->create_local_port(portName.data(), direction);
+      auto ret = this->filter->create_local_port(portName.data(), direction, format);
       if (ret != stdx::error{})
       {
         self.libremidi_handle_error(self.configuration, "error creating port");
@@ -218,11 +222,12 @@ struct pipewire_helpers
     return stdx::error{};
   }
 
-  void add_callbacks(const observer_configuration& conf)
+  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;
@@ -233,18 +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;
@@ -255,12 +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));
         }
       }
     };
@@ -408,7 +413,7 @@ struct pipewire_helpers
     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>
   {
@@ -425,6 +430,7 @@ struct pipewire_helpers
     }
 
     return {{
+        .api = Api,
         .client = 0,
         .port = port.id,
         .manufacturer = "",
@@ -436,8 +442,10 @@ 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 observer_configuration& conf, const pipewire_context& ctx) noexcept
+  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>>
   {
@@ -452,7 +460,8 @@ struct pipewire_helpers
           for (auto& port :
                (Direction == SPA_DIRECTION_INPUT ? node.second.inputs : node.second.outputs))
           {
-            ret.push_back(to_port_info<Direction>(port));
+            if (port.format.find(format) != std::string::npos)
+              ret.push_back(to_port_info<Direction, Api>(port));
           }
         }
 
@@ -462,7 +471,8 @@ struct pipewire_helpers
           for (auto& port :
                (Direction == SPA_DIRECTION_INPUT ? node.second.inputs : node.second.outputs))
           {
-            ret.push_back(to_port_info<Direction>(port));
+            if (port.format.find(format) != std::string::npos)
+              ret.push_back(to_port_info<Direction, Api>(port));
           }
         }
     }
@@ -471,3 +481,7 @@ struct pipewire_helpers
   }
 };
 }
+
+#if defined(__clang__)
+  #pragma clang diagnostic pop
+#endif

include/libremidi/backends/pipewire/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_pipewire final
     : public midi1::in_api
@@ -47,7 +47,8 @@ public:
 
   stdx::error open_port(const input_port& in_port, std::string_view name) override
   {
-    if (auto err = create_local_port(*this, name, SPA_DIRECTION_INPUT); err != stdx::error{})
+    if (auto err = create_local_port(*this, name, SPA_DIRECTION_INPUT, "8 bit raw midi");
+        err != stdx::error{})
       return err;
 
     if (auto err = link_ports(*this, in_port); err != stdx::error{})
@@ -59,7 +60,8 @@ public:
 
   stdx::error open_virtual_port(std::string_view name) override
   {
-    if (auto err = create_local_port(*this, name, SPA_DIRECTION_INPUT); err != stdx::error{})
+    if (auto err = create_local_port(*this, name, SPA_DIRECTION_INPUT, "8 bit raw midi");
+        err != stdx::error{})
       return err;
 
     start_thread();
@@ -72,10 +74,7 @@ public:
     return do_close_port();
   }
 
-  stdx::error set_port_name(std::string_view port_name) override
+  stdx::error set_port_name(std::string_view port_name) override { return rename_port(port_name); }
-  {
-    return rename_port(port_name);
-  }
 
   timestamp absolute_timestamp() const noexcept override { return system_ns(); }
 

include/libremidi/backends/pipewire/midi_out.hpp

@@ -5,9 +5,7 @@
 
 #include <readerwriterqueue.h>
 
-#include <semaphore>
+NAMESPACE_LIBREMIDI
-
-namespace libremidi
 {
 class midi_out_pipewire
     : public midi1::out_api
@@ -50,7 +48,8 @@ public:
 
   stdx::error open_port(const output_port& out_port, std::string_view name) override
   {
-    if (auto err = create_local_port(*this, name, SPA_DIRECTION_OUTPUT); err != stdx::error{})
+    if (auto err = create_local_port(*this, name, SPA_DIRECTION_OUTPUT, "8 bit raw midi");
+        err != stdx::error{})
       return err;
 
     this->filter->set_port_buffer(configuration.output_buffer_size);
@@ -64,7 +63,8 @@ public:
 
   stdx::error open_virtual_port(std::string_view name) override
   {
-    if (auto err = create_local_port(*this, name, SPA_DIRECTION_OUTPUT); err != stdx::error{})
+    if (auto err = create_local_port(*this, name, SPA_DIRECTION_OUTPUT, "8 bit raw midi");
+        err != stdx::error{})
       return err;
 
     this->filter->set_port_buffer(configuration.output_buffer_size);
@@ -79,10 +79,7 @@ public:
     return do_close_port();
   }
 
-  stdx::error set_port_name(std::string_view port_name) override
+  stdx::error set_port_name(std::string_view port_name) override { return rename_port(port_name); }
-  {
-    return rename_port(port_name);
-  }
 
   int process(spa_io_position* pos)
   {
@@ -121,8 +118,9 @@ public:
         continue;
       }
 
-      spa_pod_builder_control(&build, m.timestamp, SPA_CONTROL_Midi);
+      spa_pod_builder_control(&build, static_cast<int32_t>(m.timestamp), SPA_CONTROL_Midi);
-      int res = spa_pod_builder_bytes(&build, m.bytes.data(), m.bytes.size());
+      int res
+          = spa_pod_builder_bytes(&build, m.bytes.data(), static_cast<uint32_t>(m.bytes.size()));
 
       // Try again next buffer
       if (res == -ENOSPC)