wasapi: detect device changes and handle disconnection gracefully

src/mixer/plugins/WasapiMixerPlugin.cxx

@@ -19,6 +19,11 @@
 #include <endpointvolume.h>
 #include <mmdeviceapi.h>
 
+#include "Log.hxx"
+#include "util/Domain.hxx"
+
+static constexpr Domain wasapi_mixer_domain("wasapi_mixer");
+
 class WasapiMixer final : public Mixer {
 	WasapiOutput &output;
 
@@ -35,69 +40,80 @@ class WasapiMixer final : public Mixer {
 		if (!com_worker)
 			return -1;
 
-		auto future = com_worker->Async([&]() -> int {
-			HRESULT result;
-			float volume_level;
-
-			if (wasapi_is_exclusive(output)) {
-				auto endpoint_volume =
-					Activate<IAudioEndpointVolume>(*wasapi_output_get_device(output));
-
-				result = endpoint_volume->GetMasterVolumeLevelScalar(
-					&volume_level);
-				if (FAILED(result)) {
-					throw MakeHResultError(result,
-							       "Unable to get master "
-							       "volume level");
+		try {
+			auto future = com_worker->Async([&]() -> int {
+				HRESULT result;
+				float volume_level;
+
+				if (wasapi_is_exclusive(output)) {
+					auto endpoint_volume =
+						Activate<IAudioEndpointVolume>(*wasapi_output_get_device(output));
+
+					result = endpoint_volume->GetMasterVolumeLevelScalar(
+						&volume_level);
+					if (FAILED(result)) {
+						throw MakeHResultError(result,
+								       "Unable to get master "
+								       "volume level");
+					}
+				} else {
+					auto session_volume =
+						GetService<ISimpleAudioVolume>(*wasapi_output_get_client(output));
+
+					result = session_volume->GetMasterVolume(&volume_level);
+					if (FAILED(result)) {
+						throw MakeHResultError(
+							result, "Unable to get master volume");
+					}
 				}
-			} else {
-				auto session_volume =
-					GetService<ISimpleAudioVolume>(*wasapi_output_get_client(output));
-
-				result = session_volume->GetMasterVolume(&volume_level);
-				if (FAILED(result)) {
-					throw MakeHResultError(
-						result, "Unable to get master volume");
-				}
-			}
 
-			return std::lround(volume_level * 100.0f);
-		});
-		return future.get();
+				return std::lround(volume_level * 100.0f);
+			});
+			return future.get();
+		} catch (...) {
+			LogDebug(wasapi_mixer_domain,
+				 "Failed to get volume, device may be disconnected");
+			return -1;
+		}
 	}
 
 	void SetVolume(unsigned volume) override {
 		auto com_worker = wasapi_output_get_com_worker(output);
 		if (!com_worker)
-			throw std::runtime_error("Cannot set WASAPI volume");
-
-		com_worker->Async([&]() {
-			HRESULT result;
-			const float volume_level = volume / 100.0f;
-
-			if (wasapi_is_exclusive(output)) {
-				auto endpoint_volume =
-					Activate<IAudioEndpointVolume>(*wasapi_output_get_device(output));
-
-				result = endpoint_volume->SetMasterVolumeLevelScalar(
-					volume_level, nullptr);
-				if (FAILED(result)) {
-					throw MakeHResultError(
-						result,
-						"Unable to set master volume level");
-				}
-			} else {
-				auto session_volume =
-					GetService<ISimpleAudioVolume>(*wasapi_output_get_client(output));
-
-				result = session_volume->SetMasterVolume(volume_level,
-									 nullptr);
-				if (FAILED(result)) {
-					throw MakeHResultError(
-						result, "Unable to set master volume");
+			return;
+
+		try {
+			com_worker->Async([&]() {
+				HRESULT result;
+				const float volume_level = volume / 100.0f;
+
+				if (wasapi_is_exclusive(output)) {
+					auto endpoint_volume =
+						Activate<IAudioEndpointVolume>(*wasapi_output_get_device(output));
+
+					result = endpoint_volume->SetMasterVolumeLevelScalar(
+						volume_level, nullptr);
+					if (FAILED(result)) {
+						throw MakeHResultError(
+							result,
+							"Unable to set master volume level");
+					}
+				} else {
+					auto session_volume =
+						GetService<ISimpleAudioVolume>(*wasapi_output_get_client(output));
+
+					result = session_volume->SetMasterVolume(volume_level,
+										 nullptr);
+					if (FAILED(result)) {
+						throw MakeHResultError(
+							result, "Unable to set master volume");
+					}
 				}
-			}
-		}).get();
+			}).get();
+		} catch (...) {
+			LogDebug(wasapi_mixer_domain,
+				 "Failed to set volume, device may be disconnected");
+		}
 	}
 };
 

src/output/Control.hxx

@@ -586,10 +586,7 @@ private:
 	/**
 	 * An error has occurred, and this output must be closed.
 	 */
-	void InternalCloseError(std::exception_ptr e) noexcept {
-		Failure(e);
-		InternalClose(false);
-	}
+	void InternalCloseError(std::exception_ptr e) noexcept;
 
 	/**
 	 * Runs inside the OutputThread.

src/output/Interface.hxx

@@ -198,6 +198,16 @@ public:
 	 */
 	virtual void Cancel() noexcept {}
 
+	/**
+	 * Returns true if the most recent error was caused by an
+	 * audio device change (e.g. default device switched).  The
+	 * output framework may use this to skip the fail timer and
+	 * reopen the output immediately.
+	 */
+	virtual bool IsDeviceChange() const noexcept {
+		return false;
+	}
+
 	/**
 	 * Pause the device.  If supported, it may perform a special
 	 * action, which keeps the device open, but does not play

src/output/Thread.cxx

@@ -4,6 +4,7 @@
 #include "Control.hxx"
 #include "Error.hxx"
 #include "Filtered.hxx"
+#include "Interface.hxx"
 #include "Client.hxx"
 #include "Domain.hxx"
 #include "lib/fmt/AudioFormatFormatter.hxx"
@@ -183,6 +184,20 @@ AudioOutputControl::InternalClose(bool drain) noexcept
 	source.Close();
 }
 
+void
+AudioOutputControl::InternalCloseError(std::exception_ptr e) noexcept
+{
+	Failure(e);
+
+	/* If the plugin reports a device change (e.g. default
+	   output switched on Windows), bypass the fail timer so
+	   the output gets reopened immediately. */
+	if (output->output->IsDeviceChange())
+		fail_timer.Reset();
+
+	InternalClose(false);
+}
+
 inline void
 AudioOutputControl::InternalCheckClose(bool drain) noexcept
 {

src/output/plugins/wasapi/DeviceNotification.hxx

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright The Music Player Daemon Project
+
+#ifndef MPD_WASAPI_DEVICE_NOTIFICATION_HXX
+#define MPD_WASAPI_DEVICE_NOTIFICATION_HXX
+
+#include <atomic>
+#include <mmdeviceapi.h>
+
+#include <handleapi.h>
+#include <synchapi.h>
+
+/**
+ * IMMNotificationClient implementation that detects default audio
+ * device changes on Windows.
+ */
+class WasapiDeviceNotification final : public IMMNotificationClient {
+	std::atomic_bool &device_changed;
+	HANDLE device_event;
+	LONG ref_count = 1;
+
+public:
+	WasapiDeviceNotification(std::atomic_bool &_device_changed,
+				HANDLE _device_event) noexcept
+		:device_changed(_device_changed),
+		 device_event(_device_event) {}
+
+	/* IUnknown */
+	HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid,
+					      void **ppv) noexcept override {
+		if (riid == IID_IUnknown ||
+		    riid == __uuidof(IMMNotificationClient)) {
+			*ppv = static_cast<IMMNotificationClient *>(this);
+			AddRef();
+			return S_OK;
+		}
+		*ppv = nullptr;
+		return E_NOINTERFACE;
+	}
+
+	ULONG STDMETHODCALLTYPE AddRef() noexcept override {
+		return InterlockedIncrement(&ref_count);
+	}
+
+	ULONG STDMETHODCALLTYPE Release() noexcept override {
+		ULONG count = InterlockedDecrement(&ref_count);
+		if (count == 0)
+			delete this;
+		return count;
+	}
+
+	/* IMMNotificationClient */
+	HRESULT STDMETHODCALLTYPE
+	OnDeviceStateChanged(LPCWSTR, DWORD) noexcept override {
+		return S_OK;
+	}
+
+	HRESULT STDMETHODCALLTYPE
+	OnDeviceAdded(LPCWSTR) noexcept override {
+		return S_OK;
+	}
+
+	HRESULT STDMETHODCALLTYPE
+	OnDeviceRemoved(LPCWSTR) noexcept override {
+		return S_OK;
+	}
+
+	HRESULT STDMETHODCALLTYPE
+	OnDefaultDeviceChanged(EDataFlow flow, ERole role,
+			      LPCWSTR) noexcept override {
+		if (flow == eRender && role == eMultimedia) {
+			device_changed.store(true, std::memory_order_release);
+			SetEvent(device_event);
+		}
+		return S_OK;
+	}
+
+	HRESULT STDMETHODCALLTYPE
+	OnPropertyValueChanged(LPCWSTR,
+			      const PROPERTYKEY) noexcept override {
+		return S_OK;
+	}
+};
+
+#endif