src/output: add wasapi output and mixer plugin

src/mixer/MixerList.hxx

@@ -36,6 +36,7 @@ extern const MixerPlugin oss_mixer_plugin;
 extern const MixerPlugin osx_mixer_plugin;
 extern const MixerPlugin pulse_mixer_plugin;
 extern const MixerPlugin winmm_mixer_plugin;
+extern const MixerPlugin wasapi_mixer_plugin;
 extern const MixerPlugin sndio_mixer_plugin;
 
 #endif

src/mixer/plugins/WasapiMixerPlugin.cxx

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "mixer/MixerInternal.hxx"
+#include "output/plugins/WasapiOutputPlugin.hxx"
+#include "win32/Com.hxx"
+#include "win32/HResult.hxx"
+
+#include <cmath>
+#include <endpointvolume.h>
+#include <optional>
+
+class WasapiMixer final : public Mixer {
+	WasapiOutput &output;
+	std::optional<COM> com;
+
+public:
+	WasapiMixer(WasapiOutput &_output, MixerListener &_listener)
+	: Mixer(wasapi_mixer_plugin, _listener), output(_output) {}
+
+	void Open() override { com.emplace(); }
+
+	void Close() noexcept override { com.reset(); }
+
+	int GetVolume() override {
+		HRESULT result;
+		float volume_level;
+
+		if (wasapi_is_exclusive(output)) {
+			ComPtr<IAudioEndpointVolume> endpoint_volume;
+			result = wasapi_output_get_device(output)->Activate(
+				__uuidof(IAudioEndpointVolume), CLSCTX_ALL, nullptr,
+				endpoint_volume.AddressCast());
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get device endpoint volume");
+			}
+
+			result = endpoint_volume->GetMasterVolumeLevelScalar(
+				&volume_level);
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get master volume level");
+			}
+		} else {
+			ComPtr<ISimpleAudioVolume> session_volume;
+			result = wasapi_output_get_client(output)->GetService(
+				__uuidof(ISimpleAudioVolume),
+				session_volume.AddressCast<void>());
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get client session volume");
+			}
+
+			result = session_volume->GetMasterVolume(&volume_level);
+			if (FAILED(result)) {
+				throw FormatHResultError(result,
+							 "Unable to get master volume");
+			}
+		}
+
+		return std::lround(volume_level * 100.0f);
+	}
+
+	void SetVolume(unsigned volume) override {
+		HRESULT result;
+		const float volume_level = volume / 100.0f;
+
+		if (wasapi_is_exclusive(output)) {
+			ComPtr<IAudioEndpointVolume> endpoint_volume;
+			result = wasapi_output_get_device(output)->Activate(
+				__uuidof(IAudioEndpointVolume), CLSCTX_ALL, nullptr,
+				endpoint_volume.AddressCast());
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get device endpoint volume");
+			}
+
+			result = endpoint_volume->SetMasterVolumeLevelScalar(volume_level,
+									     nullptr);
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to set master volume level");
+			}
+		} else {
+			ComPtr<ISimpleAudioVolume> session_volume;
+			result = wasapi_output_get_client(output)->GetService(
+				__uuidof(ISimpleAudioVolume),
+				session_volume.AddressCast<void>());
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get client session volume");
+			}
+
+			result = session_volume->SetMasterVolume(volume_level, nullptr);
+			if (FAILED(result)) {
+				throw FormatHResultError(result,
+							 "Unable to set master volume");
+			}
+		}
+	}
+};
+
+static Mixer *wasapi_mixer_init(EventLoop &, AudioOutput &ao, MixerListener &listener,
+				const ConfigBlock &) {
+	return new WasapiMixer(wasapi_output_downcast(ao), listener);
+}
+
+const MixerPlugin wasapi_mixer_plugin = {
+	wasapi_mixer_init,
+	false,
+};

src/mixer/plugins/meson.build

@@ -31,7 +31,10 @@ if libsndio_dep.found()
 endif
 
 if is_windows
-  mixer_plugins_sources += 'WinmmMixerPlugin.cxx'
+  mixer_plugins_sources += [
+    'WinmmMixerPlugin.cxx',
+    'WasapiMixerPlugin.cxx',
+  ]
 endif
 
 if is_android

src/output/Registry.cxx

@@ -38,7 +38,12 @@
 #include "plugins/ShoutOutputPlugin.hxx"
 #include "plugins/sles/SlesOutputPlugin.hxx"
 #include "plugins/SolarisOutputPlugin.hxx"
+#ifdef ENABLE_WINMM_OUTPUT
 #include "plugins/WinmmOutputPlugin.hxx"
+#endif
+#ifdef ENABLE_WASAPI_OUTPUT
+#include "plugins/WasapiOutputPlugin.hxx"
+#endif
 #include "util/StringAPI.hxx"
 
 const AudioOutputPlugin *const audio_output_plugins[] = {
@@ -93,6 +98,9 @@ const AudioOutputPlugin *const audio_output_plugins[] = {
 #endif
 #ifdef ENABLE_WINMM_OUTPUT
 	&winmm_output_plugin,
+#endif
+#ifdef ENABLE_WASAPI_OUTPUT
+	&wasapi_output_plugin,
 #endif
 	nullptr
 };

src/output/plugins/WasapiOutputPlugin.cxx

@@ -0,0 +1,824 @@
+/*
+ * Copyright 2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include <initguid.h>
+
+#include "Log.hxx"
+#include "WasapiOutputPlugin.hxx"
+#include "lib/icu/Win32.hxx"
+#include "mixer/MixerList.hxx"
+#include "thread/Cond.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Thread.hxx"
+#include "util/AllocatedString.hxx"
+#include "util/Domain.hxx"
+#include "util/RuntimeError.hxx"
+#include "util/ScopeExit.hxx"
+#include "win32/Com.hxx"
+#include "win32/ComHeapPtr.hxx"
+#include "win32/HResult.hxx"
+#include "win32/WinEvent.hxx"
+
+#include <algorithm>
+#include <boost/lockfree/spsc_queue.hpp>
+#include <cinttypes>
+#include <cmath>
+#include <functiondiscoverykeys_devpkey.h>
+#include <optional>
+#include <variant>
+
+namespace {
+static constexpr Domain wasapi_output_domain("wasapi_output");
+
+gcc_const constexpr uint32_t GetChannelMask(const uint8_t channels) noexcept {
+	switch (channels) {
+	case 1:
+		return KSAUDIO_SPEAKER_MONO;
+	case 2:
+		return KSAUDIO_SPEAKER_STEREO;
+	case 3:
+		return SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER;
+	case 4:
+		return KSAUDIO_SPEAKER_QUAD;
+	case 5:
+		return SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER |
+		       SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT;
+	case 6:
+		return KSAUDIO_SPEAKER_5POINT1;
+	case 7:
+		return KSAUDIO_SPEAKER_5POINT1 | SPEAKER_BACK_CENTER;
+	case 8:
+		return KSAUDIO_SPEAKER_7POINT1_SURROUND;
+	default:
+		gcc_unreachable();
+	}
+}
+
+template <typename Functor>
+inline bool SafeTry(Functor &&functor) {
+	try {
+		functor();
+		return true;
+	} catch (std::runtime_error &err) {
+		FormatError(wasapi_output_domain, "%s", err.what());
+		return false;
+	}
+}
+
+template <typename Functor>
+inline bool SafeSilenceTry(Functor &&functor) {
+	try {
+		functor();
+		return true;
+	} catch (std::runtime_error &err) {
+		return false;
+	}
+}
+
+inline void SetFormat(WAVEFORMATEXTENSIBLE &device_format,
+		      const AudioFormat &audio_format) noexcept {
+	device_format.dwChannelMask = GetChannelMask(audio_format.channels);
+	device_format.Format.wFormatTag = WAVE_FORMAT_EXTENSIBLE;
+	device_format.Format.nChannels = audio_format.channels;
+	device_format.Format.nSamplesPerSec = audio_format.sample_rate;
+	device_format.Format.nBlockAlign = audio_format.GetFrameSize();
+	device_format.Format.nAvgBytesPerSec =
+		audio_format.sample_rate * audio_format.GetFrameSize();
+	device_format.Format.wBitsPerSample = audio_format.GetSampleSize() * 8;
+	device_format.Format.cbSize = sizeof(WAVEFORMATEXTENSIBLE) - sizeof(WAVEFORMATEX);
+	device_format.Samples.wValidBitsPerSample = audio_format.GetSampleSize() * 8;
+	if (audio_format.format == SampleFormat::FLOAT) {
+		device_format.SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
+	} else {
+		device_format.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
+	}
+}
+
+inline constexpr const unsigned int kErrorId = -1;
+
+} // namespace
+
+class WasapiOutputThread : public Thread {
+public:
+	enum class Status : uint32_t { FINISH, PLAY, PAUSE };
+	WasapiOutputThread(std::shared_ptr<WinEvent> _event, ComPtr<IAudioClient> _client,
+			   ComPtr<IAudioRenderClient> &&_render_client,
+			   const UINT32 _frame_size, const UINT32 _buffer_size_in_frames,
+			   bool _is_exclusive,
+			   boost::lockfree::spsc_queue<BYTE> &_spsc_buffer)
+	: Thread(BIND_THIS_METHOD(Work)), event(std::move(_event)),
+	  client(std::move(_client)), render_client(std::move(_render_client)),
+	  frame_size(_frame_size), buffer_size_in_frames(_buffer_size_in_frames),
+	  is_exclusive(_is_exclusive), spsc_buffer(_spsc_buffer) {}
+	void Finish() noexcept { return SetStatus(Status::FINISH); }
+	void Play() noexcept { return SetStatus(Status::PLAY); }
+	void Pause() noexcept { return SetStatus(Status::PAUSE); }
+	void WaitWrite() noexcept {
+		std::unique_lock<Mutex> lock(write.mutex);
+		write.cond.wait(lock);
+	}
+	void CheckException() {
+		std::unique_lock<Mutex> lock(error.mutex);
+		if (error.error_ptr) {
+			std::exception_ptr err = std::exchange(error.error_ptr, nullptr);
+			error.cond.notify_all();
+			std::rethrow_exception(err);
+		}
+	}
+
+private:
+	std::shared_ptr<WinEvent> event;
+	std::optional<COM> com;
+	ComPtr<IAudioClient> client;
+	ComPtr<IAudioRenderClient> render_client;
+	const UINT32 frame_size;
+	const UINT32 buffer_size_in_frames;
+	bool is_exclusive;
+	boost::lockfree::spsc_queue<BYTE> &spsc_buffer;
+	alignas(BOOST_LOCKFREE_CACHELINE_BYTES) std::atomic<Status> status =
+		Status::PAUSE;
+	alignas(BOOST_LOCKFREE_CACHELINE_BYTES) struct {
+		Mutex mutex;
+		Cond cond;
+	} write{};
+	alignas(BOOST_LOCKFREE_CACHELINE_BYTES) struct {
+		Mutex mutex;
+		Cond cond;
+		std::exception_ptr error_ptr = nullptr;
+	} error{};
+
+	void SetStatus(Status s) noexcept {
+		status.store(s);
+		event->Set();
+	}
+	void Work() noexcept;
+};
+
+class WasapiOutput final : public AudioOutput {
+public:
+	static AudioOutput *Create(EventLoop &, const ConfigBlock &block);
+	WasapiOutput(const ConfigBlock &block);
+	void Enable() override;
+	void Disable() noexcept override;
+	void Open(AudioFormat &audio_format) override;
+	void Close() noexcept override;
+	std::chrono::steady_clock::duration Delay() const noexcept override;
+	size_t Play(const void *chunk, size_t size) override;
+	void Drain() override;
+	bool Pause() override;
+
+	constexpr bool Exclusive() const { return is_exclusive; }
+	constexpr size_t FrameSize() const { return device_format.Format.nBlockAlign; }
+	constexpr size_t SampleRate() const {
+		return device_format.Format.nSamplesPerSec;
+	}
+
+private:
+	bool is_started = false;
+	bool is_exclusive;
+	bool enumerate_devices;
+	std::string device_config;
+	std::vector<std::pair<unsigned int, AllocatedString<char>>> device_desc;
+	std::shared_ptr<WinEvent> event;
+	std::optional<COM> com;
+	ComPtr<IMMDeviceEnumerator> enumerator;
+	ComPtr<IMMDevice> device;
+	ComPtr<IAudioClient> client;
+	WAVEFORMATEXTENSIBLE device_format;
+	std::unique_ptr<WasapiOutputThread> thread;
+	std::unique_ptr<boost::lockfree::spsc_queue<BYTE>> spsc_buffer;
+	std::size_t watermark;
+
+	friend bool wasapi_is_exclusive(WasapiOutput &output) noexcept;
+	friend IMMDevice *wasapi_output_get_device(WasapiOutput &output) noexcept;
+	friend IAudioClient *wasapi_output_get_client(WasapiOutput &output) noexcept;
+
+	void FindExclusiveFormatSupported(AudioFormat &audio_format);
+	void FindSharedFormatSupported(AudioFormat &audio_format);
+	void EnumerateDevices();
+	void GetDevice(unsigned int index);
+	unsigned int SearchDevice(std::string_view name);
+	void GetDefaultDevice();
+};
+
+WasapiOutput &wasapi_output_downcast(AudioOutput &output) noexcept {
+	return static_cast<WasapiOutput &>(output);
+}
+
+bool wasapi_is_exclusive(WasapiOutput &output) noexcept { return output.is_exclusive; }
+
+IMMDevice *wasapi_output_get_device(WasapiOutput &output) noexcept {
+	return output.device.get();
+}
+
+IAudioClient *wasapi_output_get_client(WasapiOutput &output) noexcept {
+	return output.client.get();
+}
+
+void WasapiOutputThread::Work() noexcept {
+	FormatDebug(wasapi_output_domain, "Working thread started");
+	try {
+		com.emplace();
+	} catch (...) {
+		std::unique_lock<Mutex> lock(error.mutex);
+		error.error_ptr = std::current_exception();
+		error.cond.wait(lock);
+		assert(error.error_ptr == nullptr);
+		return;
+	}
+	while (true) {
+		try {
+			event->Wait(INFINITE);
+
+			Status current_state = status.load();
+			if (current_state == Status::FINISH) {
+				FormatDebug(wasapi_output_domain,
+					    "Working thread stopped");
+				return;
+			}
+
+			AtScopeExit(&) { write.cond.notify_all(); };
+
+			HRESULT result;
+			UINT32 data_in_frames;
+			result = client->GetCurrentPadding(&data_in_frames);
+			if (FAILED(result)) {
+				throw FormatHResultError(result,
+							 "Failed to get current padding");
+			}
+
+			UINT32 write_in_frames = buffer_size_in_frames;
+			if (!is_exclusive) {
+				if (data_in_frames >= buffer_size_in_frames) {
+					continue;
+				}
+				write_in_frames -= data_in_frames;
+			} else if (data_in_frames >= buffer_size_in_frames * 2) {
+				continue;
+			}
+
+			BYTE *data;
+
+			result = render_client->GetBuffer(write_in_frames, &data);
+			if (FAILED(result)) {
+				throw FormatHResultError(result, "Failed to get buffer");
+			}
+
+			AtScopeExit(&) {
+				render_client->ReleaseBuffer(write_in_frames, 0);
+			};
+
+			const UINT32 write_size = write_in_frames * frame_size;
+			UINT32 new_data_size = 0;
+			if (current_state == Status::PLAY) {
+				new_data_size = spsc_buffer.pop(data, write_size);
+			} else {
+				FormatDebug(wasapi_output_domain,
+					    "Working thread paused");
+			}
+			std::fill_n(data + new_data_size, write_size - new_data_size, 0);
+		} catch (...) {
+			std::unique_lock<Mutex> lock(error.mutex);
+			error.error_ptr = std::current_exception();
+			error.cond.wait(lock);
+			assert(error.error_ptr == nullptr);
+		}
+	}
+}
+
+AudioOutput *WasapiOutput::Create(EventLoop &, const ConfigBlock &block) {
+	return new WasapiOutput(block);
+}
+
+WasapiOutput::WasapiOutput(const ConfigBlock &block)
+: AudioOutput(FLAG_ENABLE_DISABLE | FLAG_PAUSE),
+  is_exclusive(block.GetBlockValue("exclusive", false)),
+  enumerate_devices(block.GetBlockValue("enumerate", false)),
+  device_config(block.GetBlockValue("device", "")) {}
+
+void WasapiOutput::Enable() {
+	com.emplace();
+	event = std::make_shared<WinEvent>();
+	enumerator.CoCreateInstance(__uuidof(MMDeviceEnumerator), nullptr,
+				    CLSCTX_INPROC_SERVER);
+
+	device_desc.clear();
+	device.reset();
+
+	if (enumerate_devices && SafeTry([this]() { EnumerateDevices(); })) {
+		for (const auto &desc : device_desc) {
+			FormatDefault(wasapi_output_domain, "Device \"%u\" \"%s\"",
+				      desc.first, desc.second.c_str());
+		}
+	}
+
+	unsigned int id = kErrorId;
+	if (!device_config.empty()) {
+		if (!SafeSilenceTry([this, &id]() { id = std::stoul(device_config); })) {
+			id = SearchDevice(device_config);
+		}
+	}
+
+	if (id != kErrorId) {
+		SafeTry([this, id]() { GetDevice(id); });
+	}
+
+	if (!device) {
+		GetDefaultDevice();
+	}
+
+	device_desc.clear();
+}
+
+void WasapiOutput::Disable() noexcept {
+	if (thread) {
+		try {
+			thread->Finish();
+			thread->Join();
+		} catch (std::exception &err) {
+			FormatError(wasapi_output_domain, "exception while disabling: %s",
+				    err.what());
+		}
+		thread.reset();
+		spsc_buffer.reset();
+		client.reset();
+	}
+	device.reset();
+	enumerator.reset();
+	com.reset();
+	event.reset();
+}
+
+void WasapiOutput::Open(AudioFormat &audio_format) {
+	if (audio_format.channels == 0) {
+		throw FormatInvalidArgument("channels should > 0");
+	}
+
+	client.reset();
+
+	HRESULT result;
+	result = device->Activate(__uuidof(IAudioClient), CLSCTX_ALL, nullptr,
+				  client.AddressCast());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to activate audio client");
+	}
+
+	if (audio_format.format == SampleFormat::S24_P32) {
+		audio_format.format = SampleFormat::S32;
+	}
+	if (audio_format.channels > 8) {
+		audio_format.channels = 8;
+	}
+
+	if (Exclusive()) {
+		FindExclusiveFormatSupported(audio_format);
+	} else {
+		FindSharedFormatSupported(audio_format);
+	}
+
+	using s = std::chrono::seconds;
+	using ms = std::chrono::milliseconds;
+	using ns = std::chrono::nanoseconds;
+	using hundred_ns = std::chrono::duration<uint64_t, std::ratio<1, 10000000>>;
+
+	// The unit in REFERENCE_TIME is hundred nanoseconds
+	REFERENCE_TIME device_period;
+	result = client->GetDevicePeriod(&device_period, nullptr);
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to get device period");
+	}
+	FormatDebug(wasapi_output_domain, "Device period: %I64u ns",
+		    size_t(ns(hundred_ns(device_period)).count()));
+
+	REFERENCE_TIME buffer_duration = device_period;
+	if (!Exclusive()) {
+		const REFERENCE_TIME align = hundred_ns(ms(50)).count();
+		buffer_duration = (align / device_period) * device_period;
+	}
+	FormatDebug(wasapi_output_domain, "Buffer duration: %I64u ns",
+		    size_t(ns(hundred_ns(buffer_duration)).count()));
+
+	if (Exclusive()) {
+		result = client->Initialize(
+			AUDCLNT_SHAREMODE_EXCLUSIVE,
+			AUDCLNT_STREAMFLAGS_NOPERSIST | AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
+			buffer_duration, buffer_duration,
+			reinterpret_cast<WAVEFORMATEX *>(&device_format), nullptr);
+		if (result == AUDCLNT_E_BUFFER_SIZE_NOT_ALIGNED) {
+			// https://docs.microsoft.com/en-us/windows/win32/api/audioclient/nf-audioclient-iaudioclient-initialize
+			UINT32 buffer_size_in_frames = 0;
+			result = client->GetBufferSize(&buffer_size_in_frames);
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to get audio client buffer size");
+			}
+			buffer_duration = std::ceil(
+				double(buffer_size_in_frames * hundred_ns(s(1)).count()) /
+				SampleRate());
+			FormatDebug(wasapi_output_domain,
+				    "Aligned buffer duration: %I64u ns",
+				    size_t(ns(hundred_ns(buffer_duration)).count()));
+			client.reset();
+			result = device->Activate(__uuidof(IAudioClient), CLSCTX_ALL,
+						  nullptr, client.AddressCast());
+			if (FAILED(result)) {
+				throw FormatHResultError(
+					result, "Unable to activate audio client");
+			}
+			result = client->Initialize(
+				AUDCLNT_SHAREMODE_EXCLUSIVE,
+				AUDCLNT_STREAMFLAGS_NOPERSIST |
+					AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
+				buffer_duration, buffer_duration,
+				reinterpret_cast<WAVEFORMATEX *>(&device_format),
+				nullptr);
+		}
+	} else {
+		result = client->Initialize(
+			AUDCLNT_SHAREMODE_SHARED,
+			AUDCLNT_STREAMFLAGS_NOPERSIST | AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
+			buffer_duration, 0,
+			reinterpret_cast<WAVEFORMATEX *>(&device_format), nullptr);
+	}
+
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to initialize audio client");
+	}
+
+	ComPtr<IAudioRenderClient> render_client;
+	result = client->GetService(IID_PPV_ARGS(render_client.Address()));
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to get new render client");
+	}
+
+	result = client->SetEventHandle(event->handle());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to set event handler");
+	}
+
+	UINT32 buffer_size_in_frames;
+	result = client->GetBufferSize(&buffer_size_in_frames);
+	if (FAILED(result)) {
+		throw FormatHResultError(result,
+					 "Unable to get audio client buffer size");
+	}
+
+	watermark = buffer_size_in_frames * 3 * FrameSize();
+	spsc_buffer = std::make_unique<boost::lockfree::spsc_queue<BYTE>>(
+		buffer_size_in_frames * 4 * FrameSize());
+	thread = std::make_unique<WasapiOutputThread>(
+		event, client, std::move(render_client), FrameSize(),
+		buffer_size_in_frames, is_exclusive, *spsc_buffer);
+	thread->Start();
+}
+
+void WasapiOutput::Close() noexcept {
+	assert(client && thread);
+	Pause();
+	thread->Finish();
+	thread->Join();
+	thread.reset();
+	spsc_buffer.reset();
+	client.reset();
+}
+
+std::chrono::steady_clock::duration WasapiOutput::Delay() const noexcept {
+	if (!client || !is_started) {
+		return std::chrono::steady_clock::duration::zero();
+	}
+
+	const size_t data_size = spsc_buffer->read_available();
+	const size_t delay_size = std::max(data_size, watermark) - watermark;
+
+	using s = std::chrono::seconds;
+	using duration = std::chrono::steady_clock::duration;
+	auto result = duration(s(delay_size)) / device_format.Format.nAvgBytesPerSec;
+	return result;
+}
+
+size_t WasapiOutput::Play(const void *chunk, size_t size) {
+	if (!client || !thread) {
+		return 0;
+	}
+
+	do {
+		const size_t consumed_size =
+			spsc_buffer->push(static_cast<const BYTE *>(chunk), size);
+		if (consumed_size == 0) {
+			assert(is_started);
+			thread->WaitWrite();
+			continue;
+		}
+
+		if (!is_started) {
+			is_started = true;
+
+			thread->Play();
+
+			HRESULT result;
+			result = client->Start();
+			if (FAILED(result)) {
+				throw FormatHResultError(result,
+							 "Failed to start client");
+			}
+		}
+
+		thread->CheckException();
+
+		return consumed_size;
+	} while (true);
+}
+
+void WasapiOutput::Drain() {
+	spsc_buffer->consume_all([](auto &&) {});
+	thread->CheckException();
+}
+
+bool WasapiOutput::Pause() {
+	if (!client || !thread) {
+		return false;
+	}
+	if (!is_started) {
+		return true;
+	}
+
+	HRESULT result;
+	result = client->Stop();
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Failed to stop client");
+	}
+
+	is_started = false;
+	thread->Pause();
+	thread->CheckException();
+
+	return true;
+}
+
+void WasapiOutput::FindExclusiveFormatSupported(AudioFormat &audio_format) {
+	SetFormat(device_format, audio_format);
+
+	do {
+		HRESULT result;
+		result = client->IsFormatSupported(
+			AUDCLNT_SHAREMODE_EXCLUSIVE,
+			reinterpret_cast<WAVEFORMATEX *>(&device_format), nullptr);
+
+		switch (result) {
+		case S_OK:
+			return;
+		case AUDCLNT_E_UNSUPPORTED_FORMAT:
+			break;
+		default:
+			throw FormatHResultError(result, "IsFormatSupported failed");
+		}
+
+		// Trying PCM fallback.
+		if (audio_format.format == SampleFormat::FLOAT) {
+			audio_format.format = SampleFormat::S32;
+			continue;
+		}
+
+		// Trying sample rate fallback.
+		if (audio_format.sample_rate > 96000) {
+			audio_format.sample_rate = 96000;
+			continue;
+		}
+
+		if (audio_format.sample_rate > 88200) {
+			audio_format.sample_rate = 88200;
+			continue;
+		}
+
+		if (audio_format.sample_rate > 64000) {
+			audio_format.sample_rate = 64000;
+			continue;
+		}
+
+		if (audio_format.sample_rate > 48000) {
+			audio_format.sample_rate = 48000;
+			continue;
+		}
+
+		// Trying 2 channels fallback.
+		if (audio_format.channels > 2) {
+			audio_format.channels = 2;
+			continue;
+		}
+
+		// Trying S16 fallback.
+		if (audio_format.format == SampleFormat::S32) {
+			audio_format.format = SampleFormat::S16;
+			continue;
+		}
+
+		if (audio_format.sample_rate > 41100) {
+			audio_format.sample_rate = 41100;
+			continue;
+		}
+
+		throw FormatHResultError(result, "Format is not supported");
+	} while (true);
+}
+
+void WasapiOutput::FindSharedFormatSupported(AudioFormat &audio_format) {
+	HRESULT result;
+	ComHeapPtr<WAVEFORMATEX> mixer_format;
+
+	// In shared mode, different sample rate is always unsupported.
+	result = client->GetMixFormat(mixer_format.Address());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "GetMixFormat failed");
+	}
+	audio_format.sample_rate = device_format.Format.nSamplesPerSec;
+
+	SetFormat(device_format, audio_format);
+
+	ComHeapPtr<WAVEFORMATEXTENSIBLE> closest_format;
+	result = client->IsFormatSupported(
+		AUDCLNT_SHAREMODE_SHARED,
+		reinterpret_cast<WAVEFORMATEX *>(&device_format),
+		closest_format.AddressCast<WAVEFORMATEX>());
+
+	if (FAILED(result) && result != AUDCLNT_E_UNSUPPORTED_FORMAT) {
+		throw FormatHResultError(result, "IsFormatSupported failed");
+	}
+
+	switch (result) {
+	case S_OK:
+		break;
+	case AUDCLNT_E_UNSUPPORTED_FORMAT:
+	default:
+		// Trying channels fallback.
+		audio_format.channels = mixer_format->nChannels;
+
+		SetFormat(device_format, audio_format);
+
+		result = client->IsFormatSupported(
+			AUDCLNT_SHAREMODE_SHARED,
+			reinterpret_cast<WAVEFORMATEX *>(&device_format),
+			closest_format.AddressCast<WAVEFORMATEX>());
+		if (FAILED(result)) {
+			throw FormatHResultError(result, "Format is not supported");
+		}
+		break;
+	case S_FALSE:
+		if (closest_format->Format.wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
+			device_format = *closest_format;
+		} else {
+			device_format.Samples.wValidBitsPerSample =
+				device_format.Format.wBitsPerSample;
+			device_format.Format = closest_format->Format;
+			switch (std::exchange(device_format.Format.wFormatTag,
+					      WAVE_FORMAT_EXTENSIBLE)) {
+			case WAVE_FORMAT_PCM:
+				device_format.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
+				break;
+			case WAVE_FORMAT_IEEE_FLOAT:
+				device_format.SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
+				break;
+			default:
+				gcc_unreachable();
+			}
+		}
+		break;
+	}
+
+	// Copy closest match back to audio_format.
+	audio_format.channels = device_format.Format.nChannels;
+	audio_format.sample_rate = device_format.Format.nSamplesPerSec;
+	if (device_format.SubFormat == KSDATAFORMAT_SUBTYPE_PCM) {
+		switch (device_format.Format.wBitsPerSample) {
+		case 8:
+			audio_format.format = SampleFormat::S8;
+			break;
+		case 16:
+			audio_format.format = SampleFormat::S16;
+			break;
+		case 32:
+			audio_format.format = SampleFormat::S32;
+			break;
+		}
+	} else if (device_format.SubFormat == KSDATAFORMAT_SUBTYPE_IEEE_FLOAT) {
+		audio_format.format = SampleFormat::FLOAT;
+	}
+}
+
+void WasapiOutput::EnumerateDevices() {
+	if (!device_desc.empty()) {
+		return;
+	}
+
+	HRESULT result;
+
+	ComPtr<IMMDeviceCollection> device_collection;
+	result = enumerator->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE,
+						device_collection.Address());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to enumerate devices");
+	}
+
+	UINT count;
+	result = device_collection->GetCount(&count);
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Collection->GetCount failed");
+	}
+
+	device_desc.reserve(count);
+	for (UINT i = 0; i < count; ++i) {
+		ComPtr<IMMDevice> enumerated_device;
+		result = device_collection->Item(i, enumerated_device.Address());
+		if (FAILED(result)) {
+			throw FormatHResultError(result, "Collection->Item failed");
+		}
+
+		ComPtr<IPropertyStore> property_store;
+		result = enumerated_device->OpenPropertyStore(STGM_READ,
+							      property_store.Address());
+		if (FAILED(result)) {
+			throw FormatHResultError(result,
+						 "Device->OpenPropertyStore failed");
+		}
+
+		PROPVARIANT var_name;
+		PropVariantInit(&var_name);
+		AtScopeExit(&) { PropVariantClear(&var_name); };
+
+		result = property_store->GetValue(PKEY_Device_FriendlyName, &var_name);
+		if (FAILED(result)) {
+			throw FormatHResultError(result,
+						 "PropertyStore->GetValue failed");
+		}
+
+		device_desc.emplace_back(
+			i, WideCharToMultiByte(CP_UTF8,
+					       std::wstring_view(var_name.pwszVal)));
+	}
+}
+
+void WasapiOutput::GetDevice(unsigned int index) {
+	HRESULT result;
+
+	ComPtr<IMMDeviceCollection> device_collection;
+	result = enumerator->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE,
+						device_collection.Address());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Unable to enumerate devices");
+	}
+
+	result = device_collection->Item(index, device.Address());
+	if (FAILED(result)) {
+		throw FormatHResultError(result, "Collection->Item failed");
+	}
+}
+
+unsigned int WasapiOutput::SearchDevice(std::string_view name) {
+	if (!SafeTry([this]() { EnumerateDevices(); })) {
+		return kErrorId;
+	}
+	auto iter =
+		std::find_if(device_desc.cbegin(), device_desc.cend(),
+			     [&name](const auto &desc) { return desc.second == name; });
+	if (iter == device_desc.cend()) {
+		FormatError(wasapi_output_domain, "Device %.*s not founded.",
+			    int(name.size()), name.data());
+		return kErrorId;
+	}
+	FormatInfo(wasapi_output_domain, "Select device \"%u\" \"%s\"", iter->first,
+		   iter->second.c_str());
+	return iter->first;
+}
+
+void WasapiOutput::GetDefaultDevice() {
+	HRESULT result;
+	result = enumerator->GetDefaultAudioEndpoint(eRender, eMultimedia,
+						     device.Address());
+	if (FAILED(result)) {
+		throw FormatHResultError(result,
+					 "Unable to get default device for multimedia");
+	}
+}
+
+static bool wasapi_output_test_default_device() { return true; }
+
+const struct AudioOutputPlugin wasapi_output_plugin = {
+	"wasapi",
+	wasapi_output_test_default_device,
+	WasapiOutput::Create,
+	&wasapi_mixer_plugin,
+};

src/output/plugins/WasapiOutputPlugin.hxx

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_WASAPI_OUTPUT_PLUGIN_HXX
+#define MPD_WASAPI_OUTPUT_PLUGIN_HXX
+
+#include "output/Features.h"
+
+#include "../OutputAPI.hxx"
+#include "util/Compiler.h"
+#include "win32/ComPtr.hxx"
+
+#include <audioclient.h>
+#include <mmdeviceapi.h>
+
+extern const struct AudioOutputPlugin wasapi_output_plugin;
+
+class WasapiOutput;
+
+gcc_pure WasapiOutput &wasapi_output_downcast(AudioOutput &output) noexcept;
+
+gcc_pure bool wasapi_is_exclusive(WasapiOutput &output) noexcept;
+
+gcc_pure IMMDevice *wasapi_output_get_device(WasapiOutput &output) noexcept;
+
+gcc_pure IAudioClient *wasapi_output_get_client(WasapiOutput &output) noexcept;
+
+#endif

src/output/plugins/meson.build

@@ -39,7 +39,7 @@ if get_option('httpd')
     'httpd/HttpdClient.cxx',
     'httpd/HttpdOutputPlugin.cxx',
   ]
-  output_plugins_deps += [ event_dep, net_dep ]
+  output_plugins_deps += [ event_dep, net_dep, boost_dep ]
   need_encoder = true
 endif
 
@@ -143,6 +143,19 @@ else
   winmm_dep = dependency('', required: false)
 endif
 
+output_features.set('ENABLE_WASAPI_OUTPUT', is_windows)
+if is_windows
+  output_plugins_sources += [
+    'WasapiOutputPlugin.cxx',
+  ]
+  wasapi_dep = [
+    c_compiler.find_library('ksuser', required: true),
+    c_compiler.find_library('ole32', required: true),
+  ]
+else
+  wasapi_dep = dependency('', required: false)
+endif
+
 output_plugins = static_library(
   'output_plugins',
   output_plugins_sources,
@@ -158,6 +171,8 @@ output_plugins = static_library(
     openal_dep,
     sles_dep,
     winmm_dep,
+    wasapi_dep,
+    boost_dep,
   ],
 )