very, very simple WP with midi CC out

include/libremidi/backends/pipewire/config.hpp

@@ -0,0 +1,53 @@
+#pragma once
+#include <libremidi/config.hpp>
+
+#include <cinttypes>
+#include <cstdint>
+#include <functional>
+#include <string>
+
+extern "C" {
+struct pw_main_loop;
+struct pw_filter;
+struct spa_io_position;
+}
+
+namespace libremidi
+{
+using pipewire_callback_function = std::function<void(spa_io_position*)>;
+struct pipewire_callback
+{
+  int64_t token;
+  pipewire_callback_function callback;
+};
+
+struct pipewire_input_configuration
+{
+  std::string client_name = "libremidi client";
+
+  pw_main_loop* context{};
+  pw_filter* filter{};
+  std::function<void(pipewire_callback)> set_process_func;
+  std::function<void(int64_t)> clear_process_func;
+};
+
+struct pipewire_output_configuration
+{
+  std::string client_name = "libremidi client";
+
+  pw_main_loop* context{};
+  pw_filter* filter{};
+  std::function<void(pipewire_callback)> set_process_func;
+  std::function<void(int64_t)> clear_process_func;
+
+  int64_t output_buffer_size{65536};
+};
+
+struct pipewire_observer_configuration
+{
+  std::string client_name = "libremidi client";
+
+  pw_main_loop* context{};
+};
+
+}