src/audio/wasapi/SDL_wasapi_winrt.cpp - external/github.com/libsdl-org/SDL - Git at Google

 /*
   Simple DirectMedia Layer
   Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>

   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you must not
      claim that you wrote the original software. If you use this software
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.
   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
 #include "../../SDL_internal.h"

 // This is C++/CX code that the WinRT port uses to talk to WASAPI-related
 //  system APIs. The C implementation of these functions, for non-WinRT apps,
 //  is in SDL_wasapi_win32.c. The code in SDL_wasapi.c is used by both standard
 //  Windows and WinRT builds to deal with audio and calls into these functions.

 #if SDL_AUDIO_DRIVER_WASAPI && defined(__WINRT__)

 #include <Windows.h>
 #include <windows.ui.core.h>
 #include <windows.devices.enumeration.h>
 #include <windows.media.devices.h>
 #include <wrl/implements.h>
 #include <collection.h>

 extern "C" {
 #include "../../core/windows/SDL_windows.h"
 #include "SDL_audio.h"
 #include "SDL_timer.h"
 #include "../SDL_audio_c.h"
 #include "../SDL_sysaudio.h"
 }

 #define COBJMACROS
 #include <mmdeviceapi.h>
 #include <audioclient.h>

 #include "SDL_wasapi.h"

 using namespace Windows::Devices::Enumeration;
 using namespace Windows::Media::Devices;
 using namespace Windows::Foundation;
 using namespace Microsoft::WRL;

 static Platform::String ^ SDL_PKEY_AudioEngine_DeviceFormat = L"{f19f064d-082c-4e27-bc73-6882a1bb8e4c} 0";

 static void WASAPI_AddDevice(const SDL_bool iscapture, const char *devname, WAVEFORMATEXTENSIBLE *fmt, LPCWSTR devid);
 static void WASAPI_RemoveDevice(const SDL_bool iscapture, LPCWSTR devid);
 extern "C" {
 SDL_atomic_t SDL_IMMDevice_DefaultPlaybackGeneration;
 SDL_atomic_t SDL_IMMDevice_DefaultCaptureGeneration;
 }

 /* This is a list of device id strings we have inflight, so we have consistent pointers to the same device. */
 typedef struct DevIdList
 {
     WCHAR *str;
     struct DevIdList *next;
 } DevIdList;

 static DevIdList *deviceid_list = NULL;

 class SDL_WasapiDeviceEventHandler
 {
   public:
     SDL_WasapiDeviceEventHandler(const SDL_bool _iscapture);
     ~SDL_WasapiDeviceEventHandler();
     void OnDeviceAdded(DeviceWatcher ^ sender, DeviceInformation ^ args);
     void OnDeviceRemoved(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args);
     void OnDeviceUpdated(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args);
     void OnEnumerationCompleted(DeviceWatcher ^ sender, Platform::Object ^ args);
     void OnDefaultRenderDeviceChanged(Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args);
     void OnDefaultCaptureDeviceChanged(Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args);
     SDL_semaphore *completed;

   private:
     const SDL_bool iscapture;
     DeviceWatcher ^ watcher;
     Windows::Foundation::EventRegistrationToken added_handler;
     Windows::Foundation::EventRegistrationToken removed_handler;
     Windows::Foundation::EventRegistrationToken updated_handler;
     Windows::Foundation::EventRegistrationToken completed_handler;
     Windows::Foundation::EventRegistrationToken default_changed_handler;
 };

 SDL_WasapiDeviceEventHandler::SDL_WasapiDeviceEventHandler(const SDL_bool _iscapture)
     : iscapture(_iscapture), completed(SDL_CreateSemaphore(0))
 {
     if (!completed)
         return; // uhoh.

     Platform::String ^ selector = _iscapture ? MediaDevice::GetAudioCaptureSelector() : MediaDevice::GetAudioRenderSelector();
     Platform::Collections::Vector<Platform::String ^> properties;
     properties.Append(SDL_PKEY_AudioEngine_DeviceFormat);
     watcher = DeviceInformation::CreateWatcher(selector, properties.GetView());
     if (!watcher)
         return; // uhoh.

     // !!! FIXME: this doesn't need a lambda here, I think, if I make SDL_WasapiDeviceEventHandler a proper C++/CX class. --ryan.
     added_handler = watcher->Added += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformation ^>([this](DeviceWatcher ^ sender, DeviceInformation ^ args) { OnDeviceAdded(sender, args); });
     removed_handler = watcher->Removed += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformationUpdate ^>([this](DeviceWatcher ^ sender, DeviceInformationUpdate ^ args) { OnDeviceRemoved(sender, args); });
     updated_handler = watcher->Updated += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformationUpdate ^>([this](DeviceWatcher ^ sender, DeviceInformationUpdate ^ args) { OnDeviceUpdated(sender, args); });
     completed_handler = watcher->EnumerationCompleted += ref new TypedEventHandler<DeviceWatcher ^, Platform::Object ^>([this](DeviceWatcher ^ sender, Platform::Object ^ args) { OnEnumerationCompleted(sender, args); });
     if (iscapture) {
         default_changed_handler = MediaDevice::DefaultAudioCaptureDeviceChanged += ref new TypedEventHandler<Platform::Object ^, DefaultAudioCaptureDeviceChangedEventArgs ^>([this](Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args) { OnDefaultCaptureDeviceChanged(sender, args); });
     } else {
         default_changed_handler = MediaDevice::DefaultAudioRenderDeviceChanged += ref new TypedEventHandler<Platform::Object ^, DefaultAudioRenderDeviceChangedEventArgs ^>([this](Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args) { OnDefaultRenderDeviceChanged(sender, args); });
     }
     watcher->Start();
 }

 SDL_WasapiDeviceEventHandler::~SDL_WasapiDeviceEventHandler()
 {
     if (watcher) {
         watcher->Added -= added_handler;
         watcher->Removed -= removed_handler;
         watcher->Updated -= updated_handler;
         watcher->EnumerationCompleted -= completed_handler;
         watcher->Stop();
         watcher = nullptr;
     }
     if (completed) {
         SDL_DestroySemaphore(completed);
         completed = nullptr;
     }

     if (iscapture) {
         MediaDevice::DefaultAudioCaptureDeviceChanged -= default_changed_handler;
     } else {
         MediaDevice::DefaultAudioRenderDeviceChanged -= default_changed_handler;
     }
 }

 void SDL_WasapiDeviceEventHandler::OnDeviceAdded(DeviceWatcher ^ sender, DeviceInformation ^ info)
 {
     SDL_assert(sender == this->watcher);
     char *utf8dev = WIN_StringToUTF8(info->Name->Data());
     if (utf8dev) {
         WAVEFORMATEXTENSIBLE fmt;
         Platform::Object ^ obj = info->Properties->Lookup(SDL_PKEY_AudioEngine_DeviceFormat);
         if (obj) {
             IPropertyValue ^ property = (IPropertyValue ^) obj;
             Platform::Array<unsigned char> ^ data;
             property->GetUInt8Array(&data);
             SDL_memcpy(&fmt, data->Data, SDL_min(data->Length, sizeof(WAVEFORMATEXTENSIBLE)));
         } else {
             SDL_zero(fmt);
         }

         WASAPI_AddDevice(this->iscapture, utf8dev, &fmt, info->Id->Data());
         SDL_free(utf8dev);
     }
 }

 void SDL_WasapiDeviceEventHandler::OnDeviceRemoved(DeviceWatcher ^ sender, DeviceInformationUpdate ^ info)
 {
     SDL_assert(sender == this->watcher);
     WASAPI_RemoveDevice(this->iscapture, info->Id->Data());
 }

 void SDL_WasapiDeviceEventHandler::OnDeviceUpdated(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args)
 {
     SDL_assert(sender == this->watcher);
 }

 void SDL_WasapiDeviceEventHandler::OnEnumerationCompleted(DeviceWatcher ^ sender, Platform::Object ^ args)
 {
     SDL_assert(sender == this->watcher);
     SDL_SemPost(this->completed);
 }

 void SDL_WasapiDeviceEventHandler::OnDefaultRenderDeviceChanged(Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args)
 {
     SDL_assert(!this->iscapture);
     SDL_AtomicAdd(&SDL_IMMDevice_DefaultPlaybackGeneration, 1);
 }

 void SDL_WasapiDeviceEventHandler::OnDefaultCaptureDeviceChanged(Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args)
 {
     SDL_assert(this->iscapture);
     SDL_AtomicAdd(&SDL_IMMDevice_DefaultCaptureGeneration, 1);
 }

 static SDL_WasapiDeviceEventHandler *playback_device_event_handler;
 static SDL_WasapiDeviceEventHandler *capture_device_event_handler;

 int WASAPI_PlatformInit(void)
 {
     SDL_AtomicSet(&SDL_IMMDevice_DefaultPlaybackGeneration, 1);
     SDL_AtomicSet(&SDL_IMMDevice_DefaultCaptureGeneration, 1);
     return 0;
 }

 void WASAPI_PlatformDeinit(void)
 {
     DevIdList *devidlist;
     DevIdList *next;

     delete playback_device_event_handler;
     playback_device_event_handler = nullptr;
     delete capture_device_event_handler;
     capture_device_event_handler = nullptr;

     for (devidlist = deviceid_list; devidlist; devidlist = next) {
         next = devidlist->next;
         SDL_free(devidlist->str);
         SDL_free(devidlist);
     }
     deviceid_list = NULL;
 }

 void WASAPI_EnumerateEndpoints(void)
 {
     // DeviceWatchers will fire an Added event for each existing device at
     //  startup, so we don't need to enumerate them separately before
     //  listening for updates.
     playback_device_event_handler = new SDL_WasapiDeviceEventHandler(SDL_FALSE);
     capture_device_event_handler = new SDL_WasapiDeviceEventHandler(SDL_TRUE);
     SDL_SemWait(playback_device_event_handler->completed);
     SDL_SemWait(capture_device_event_handler->completed);
 }

 struct SDL_WasapiActivationHandler : public RuntimeClass<RuntimeClassFlags<ClassicCom>, FtmBase, IActivateAudioInterfaceCompletionHandler>
 {
     SDL_WasapiActivationHandler() : device(nullptr) {}
     STDMETHOD(ActivateCompleted)
     (IActivateAudioInterfaceAsyncOperation *operation);
     SDL_AudioDevice *device;
 };

 HRESULT
 SDL_WasapiActivationHandler::ActivateCompleted(IActivateAudioInterfaceAsyncOperation *async)
 {
     // Just set a flag, since we're probably in a different thread. We'll pick it up and init everything on our own thread to prevent races.
     SDL_AtomicSet(&device->hidden->just_activated, 1);
     WASAPI_UnrefDevice(device);
     return S_OK;
 }

 void WASAPI_PlatformDeleteActivationHandler(void *handler)
 {
     ((SDL_WasapiActivationHandler *)handler)->Release();
 }

 int WASAPI_GetDefaultAudioInfo(char **name, SDL_AudioSpec *spec, int iscapture)
 {
     return SDL_Unsupported();
 }

 int WASAPI_ActivateDevice(_THIS, const SDL_bool isrecovery)
 {
     LPCWSTR devid = _this->hidden->devid;
     Platform::String ^ defdevid;

     if (devid == nullptr) {
         defdevid = _this->iscapture ? MediaDevice::GetDefaultAudioCaptureId(AudioDeviceRole::Default) : MediaDevice::GetDefaultAudioRenderId(AudioDeviceRole::Default);
         if (defdevid) {
             devid = defdevid->Data();
         }
     }

     SDL_AtomicSet(&_this->hidden->just_activated, 0);

     ComPtr<SDL_WasapiActivationHandler> handler = Make<SDL_WasapiActivationHandler>();
     if (handler == nullptr) {
         return SDL_SetError("Failed to allocate WASAPI activation handler");
     }

     handler.Get()->AddRef(); // we hold a reference after ComPtr destructs on return, causing a Release, and Release ourselves in WASAPI_PlatformDeleteActivationHandler(), etc.
     handler.Get()->device = _this;
     _this->hidden->activation_handler = handler.Get();

     WASAPI_RefDevice(_this); /* completion handler will unref it. */
     IActivateAudioInterfaceAsyncOperation *async = nullptr;
     const HRESULT ret = ActivateAudioInterfaceAsync(devid, __uuidof(IAudioClient), nullptr, handler.Get(), &async);

     if (FAILED(ret) || async == nullptr) {
         if (async != nullptr) {
             async->Release();
         }
         handler.Get()->Release();
         WASAPI_UnrefDevice(_this);
         return WIN_SetErrorFromHRESULT("WASAPI can't activate requested audio endpoint", ret);
     }

     /* Spin until the async operation is complete.
      * If we don't PrepDevice before leaving this function, the bug list gets LONG:
      * - device.spec is not filled with the correct information
      * - The 'obtained' spec will be wrong for ALLOW_CHANGE properties
      * - SDL_AudioStreams will/will not be allocated at the right time
      * - SDL_assert(device->callbackspec.size == device->spec.size) will fail
      * - When the assert is ignored, skipping or a buffer overflow will occur
      */
     while (!SDL_AtomicCAS(&_this->hidden->just_activated, 1, 0)) {
         SDL_Delay(1);
     }

     HRESULT activateRes = S_OK;
     IUnknown *iunknown = nullptr;
     const HRESULT getActivateRes = async->GetActivateResult(&activateRes, &iunknown);
     async->Release();
     if (FAILED(getActivateRes)) {
         return WIN_SetErrorFromHRESULT("Failed to get WASAPI activate result", getActivateRes);
     } else if (FAILED(activateRes)) {
         return WIN_SetErrorFromHRESULT("Failed to activate WASAPI device", activateRes);
     }

     iunknown->QueryInterface(IID_PPV_ARGS(&_this->hidden->client));
     if (!_this->hidden->client) {
         return SDL_SetError("Failed to query WASAPI client interface");
     }

     if (WASAPI_PrepDevice(_this, isrecovery) == -1) {
         return -1;
     }

     return 0;
 }

 void WASAPI_PlatformThreadInit(_THIS)
 {
     // !!! FIXME: set this thread to "Pro Audio" priority.
 }

 void WASAPI_PlatformThreadDeinit(_THIS)
 {
     // !!! FIXME: set this thread to "Pro Audio" priority.
 }

 /* Everything below was copied from SDL_wasapi.c, before it got moved to SDL_immdevice.c! */

 static const GUID SDL_KSDATAFORMAT_SUBTYPE_PCM = { 0x00000001, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };
 static const GUID SDL_KSDATAFORMAT_SUBTYPE_IEEE_FLOAT = { 0x00000003, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };

 extern "C" SDL_AudioFormat
 WaveFormatToSDLFormat(WAVEFORMATEX *waveformat)
 {
     if ((waveformat->wFormatTag == WAVE_FORMAT_IEEE_FLOAT) && (waveformat->wBitsPerSample == 32)) {
         return AUDIO_F32SYS;
     } else if ((waveformat->wFormatTag == WAVE_FORMAT_PCM) && (waveformat->wBitsPerSample == 16)) {
         return AUDIO_S16SYS;
     } else if ((waveformat->wFormatTag == WAVE_FORMAT_PCM) && (waveformat->wBitsPerSample == 32)) {
         return AUDIO_S32SYS;
     } else if (waveformat->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
         const WAVEFORMATEXTENSIBLE *ext = (const WAVEFORMATEXTENSIBLE *)waveformat;
         if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_IEEE_FLOAT, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 32)) {
             return AUDIO_F32SYS;
         } else if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_PCM, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 16)) {
             return AUDIO_S16SYS;
         } else if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_PCM, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 32)) {
             return AUDIO_S32SYS;
         }
     }
     return 0;
 }

 static void WASAPI_RemoveDevice(const SDL_bool iscapture, LPCWSTR devid)
 {
     DevIdList *i;
     DevIdList *next;
     DevIdList *prev = NULL;
     for (i = deviceid_list; i; i = next) {
         next = i->next;
         if (SDL_wcscmp(i->str, devid) == 0) {
             if (prev) {
                 prev->next = next;
             } else {
                 deviceid_list = next;
             }
             SDL_RemoveAudioDevice(iscapture, i->str);
             SDL_free(i->str);
             SDL_free(i);
         } else {
             prev = i;
         }
     }
 }

 static void WASAPI_AddDevice(const SDL_bool iscapture, const char *devname, WAVEFORMATEXTENSIBLE *fmt, LPCWSTR devid)
 {
     DevIdList *devidlist;
     SDL_AudioSpec spec;

     /* You can have multiple endpoints on a device that are mutually exclusive ("Speakers" vs "Line Out" or whatever).
        In a perfect world, things that are unplugged won't be in this collection. The only gotcha is probably for
        phones and tablets, where you might have an internal speaker and a headphone jack and expect both to be
        available and switch automatically. (!!! FIXME...?) */

     /* see if we already have this one. */
     for (devidlist = deviceid_list; devidlist; devidlist = devidlist->next) {
         if (SDL_wcscmp(devidlist->str, devid) == 0) {
             return; /* we already have this. */
         }
     }

     devidlist = (DevIdList *)SDL_malloc(sizeof(*devidlist));
     if (devidlist == NULL) {
         return; /* oh well. */
     }

     devid = SDL_wcsdup(devid);
     if (!devid) {
         SDL_free(devidlist);
         return; /* oh well. */
     }

     devidlist->str = (WCHAR *)devid;
     devidlist->next = deviceid_list;
     deviceid_list = devidlist;

     SDL_zero(spec);
     spec.channels = (Uint8)fmt->Format.nChannels;
     spec.freq = fmt->Format.nSamplesPerSec;
     spec.format = WaveFormatToSDLFormat((WAVEFORMATEX *)fmt);
     SDL_AddAudioDevice(iscapture, devname, &spec, (void *)devid);
 }

 #endif // SDL_AUDIO_DRIVER_WASAPI && defined(__WINRT__)

 /* vi: set ts=4 sw=4 expandtab: */
	/*
	Simple DirectMedia Layer
	Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>

	This software is provided 'as-is', without any express or implied
	warranty. In no event will the authors be held liable for any damages
	arising from the use of this software.

	Permission is granted to anyone to use this software for any purpose,
	including commercial applications, and to alter it and redistribute it
	freely, subject to the following restrictions:

	1. The origin of this software must not be misrepresented; you must not
	claim that you wrote the original software. If you use this software
	in a product, an acknowledgment in the product documentation would be
	appreciated but is not required.
	2. Altered source versions must be plainly marked as such, and must not be
	misrepresented as being the original software.
	3. This notice may not be removed or altered from any source distribution.
	*/
	#include "../../SDL_internal.h"

	// This is C++/CX code that the WinRT port uses to talk to WASAPI-related
	// system APIs. The C implementation of these functions, for non-WinRT apps,
	// is in SDL_wasapi_win32.c. The code in SDL_wasapi.c is used by both standard
	// Windows and WinRT builds to deal with audio and calls into these functions.

	#if SDL_AUDIO_DRIVER_WASAPI && defined(__WINRT__)

	#include <Windows.h>
	#include <windows.ui.core.h>
	#include <windows.devices.enumeration.h>
	#include <windows.media.devices.h>
	#include <wrl/implements.h>
	#include <collection.h>

	extern "C" {
	#include "../../core/windows/SDL_windows.h"
	#include "SDL_audio.h"
	#include "SDL_timer.h"
	#include "../SDL_audio_c.h"
	#include "../SDL_sysaudio.h"
	}

	#define COBJMACROS
	#include <mmdeviceapi.h>
	#include <audioclient.h>

	#include "SDL_wasapi.h"

	using namespace Windows::Devices::Enumeration;
	using namespace Windows::Media::Devices;
	using namespace Windows::Foundation;
	using namespace Microsoft::WRL;

	static Platform::String ^ SDL_PKEY_AudioEngine_DeviceFormat = L"{f19f064d-082c-4e27-bc73-6882a1bb8e4c} 0";

	static void WASAPI_AddDevice(const SDL_bool iscapture, const char devname, WAVEFORMATEXTENSIBLE fmt, LPCWSTR devid);
	static void WASAPI_RemoveDevice(const SDL_bool iscapture, LPCWSTR devid);
	extern "C" {
	SDL_atomic_t SDL_IMMDevice_DefaultPlaybackGeneration;
	SDL_atomic_t SDL_IMMDevice_DefaultCaptureGeneration;
	}

	/* This is a list of device id strings we have inflight, so we have consistent pointers to the same device. */
	typedef struct DevIdList
	{
	WCHAR *str;
	struct DevIdList *next;
	} DevIdList;

	static DevIdList *deviceid_list = NULL;

	class SDL_WasapiDeviceEventHandler
	{
	public:
	SDL_WasapiDeviceEventHandler(const SDL_bool _iscapture);
	~SDL_WasapiDeviceEventHandler();
	void OnDeviceAdded(DeviceWatcher ^ sender, DeviceInformation ^ args);
	void OnDeviceRemoved(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args);
	void OnDeviceUpdated(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args);
	void OnEnumerationCompleted(DeviceWatcher ^ sender, Platform::Object ^ args);
	void OnDefaultRenderDeviceChanged(Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args);
	void OnDefaultCaptureDeviceChanged(Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args);
	SDL_semaphore *completed;

	private:
	const SDL_bool iscapture;
	DeviceWatcher ^ watcher;
	Windows::Foundation::EventRegistrationToken added_handler;
	Windows::Foundation::EventRegistrationToken removed_handler;
	Windows::Foundation::EventRegistrationToken updated_handler;
	Windows::Foundation::EventRegistrationToken completed_handler;
	Windows::Foundation::EventRegistrationToken default_changed_handler;
	};

	SDL_WasapiDeviceEventHandler::SDL_WasapiDeviceEventHandler(const SDL_bool _iscapture)
	: iscapture(_iscapture), completed(SDL_CreateSemaphore(0))
	{
	if (!completed)
	return; // uhoh.

	Platform::String ^ selector = _iscapture ? MediaDevice::GetAudioCaptureSelector() : MediaDevice::GetAudioRenderSelector();
	Platform::Collections::Vector<Platform::String ^> properties;
	properties.Append(SDL_PKEY_AudioEngine_DeviceFormat);
	watcher = DeviceInformation::CreateWatcher(selector, properties.GetView());
	if (!watcher)
	return; // uhoh.

	// !!! FIXME: this doesn't need a lambda here, I think, if I make SDL_WasapiDeviceEventHandler a proper C++/CX class. --ryan.
	added_handler = watcher->Added += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformation ^>([this](DeviceWatcher ^ sender, DeviceInformation ^ args) { OnDeviceAdded(sender, args); });
	removed_handler = watcher->Removed += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformationUpdate ^>([this](DeviceWatcher ^ sender, DeviceInformationUpdate ^ args) { OnDeviceRemoved(sender, args); });
	updated_handler = watcher->Updated += ref new TypedEventHandler<DeviceWatcher ^, DeviceInformationUpdate ^>([this](DeviceWatcher ^ sender, DeviceInformationUpdate ^ args) { OnDeviceUpdated(sender, args); });
	completed_handler = watcher->EnumerationCompleted += ref new TypedEventHandler<DeviceWatcher ^, Platform::Object ^>([this](DeviceWatcher ^ sender, Platform::Object ^ args) { OnEnumerationCompleted(sender, args); });
	if (iscapture) {
	default_changed_handler = MediaDevice::DefaultAudioCaptureDeviceChanged += ref new TypedEventHandler<Platform::Object ^, DefaultAudioCaptureDeviceChangedEventArgs ^>([this](Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args) { OnDefaultCaptureDeviceChanged(sender, args); });
	} else {
	default_changed_handler = MediaDevice::DefaultAudioRenderDeviceChanged += ref new TypedEventHandler<Platform::Object ^, DefaultAudioRenderDeviceChangedEventArgs ^>([this](Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args) { OnDefaultRenderDeviceChanged(sender, args); });
	}
	watcher->Start();
	}

	SDL_WasapiDeviceEventHandler::~SDL_WasapiDeviceEventHandler()
	{
	if (watcher) {
	watcher->Added -= added_handler;
	watcher->Removed -= removed_handler;
	watcher->Updated -= updated_handler;
	watcher->EnumerationCompleted -= completed_handler;
	watcher->Stop();
	watcher = nullptr;
	}
	if (completed) {
	SDL_DestroySemaphore(completed);
	completed = nullptr;
	}

	if (iscapture) {
	MediaDevice::DefaultAudioCaptureDeviceChanged -= default_changed_handler;
	} else {
	MediaDevice::DefaultAudioRenderDeviceChanged -= default_changed_handler;
	}
	}

	void SDL_WasapiDeviceEventHandler::OnDeviceAdded(DeviceWatcher ^ sender, DeviceInformation ^ info)
	{
	SDL_assert(sender == this->watcher);
	char *utf8dev = WIN_StringToUTF8(info->Name->Data());
	if (utf8dev) {
	WAVEFORMATEXTENSIBLE fmt;
	Platform::Object ^ obj = info->Properties->Lookup(SDL_PKEY_AudioEngine_DeviceFormat);
	if (obj) {
	IPropertyValue ^ property = (IPropertyValue ^) obj;
	Platform::Array<unsigned char> ^ data;
	property->GetUInt8Array(&data);
	SDL_memcpy(&fmt, data->Data, SDL_min(data->Length, sizeof(WAVEFORMATEXTENSIBLE)));
	} else {
	SDL_zero(fmt);
	}

	WASAPI_AddDevice(this->iscapture, utf8dev, &fmt, info->Id->Data());
	SDL_free(utf8dev);
	}
	}

	void SDL_WasapiDeviceEventHandler::OnDeviceRemoved(DeviceWatcher ^ sender, DeviceInformationUpdate ^ info)
	{
	SDL_assert(sender == this->watcher);
	WASAPI_RemoveDevice(this->iscapture, info->Id->Data());
	}

	void SDL_WasapiDeviceEventHandler::OnDeviceUpdated(DeviceWatcher ^ sender, DeviceInformationUpdate ^ args)
	{
	SDL_assert(sender == this->watcher);
	}

	void SDL_WasapiDeviceEventHandler::OnEnumerationCompleted(DeviceWatcher ^ sender, Platform::Object ^ args)
	{
	SDL_assert(sender == this->watcher);
	SDL_SemPost(this->completed);
	}

	void SDL_WasapiDeviceEventHandler::OnDefaultRenderDeviceChanged(Platform::Object ^ sender, DefaultAudioRenderDeviceChangedEventArgs ^ args)
	{
	SDL_assert(!this->iscapture);
	SDL_AtomicAdd(&SDL_IMMDevice_DefaultPlaybackGeneration, 1);
	}

	void SDL_WasapiDeviceEventHandler::OnDefaultCaptureDeviceChanged(Platform::Object ^ sender, DefaultAudioCaptureDeviceChangedEventArgs ^ args)
	{
	SDL_assert(this->iscapture);
	SDL_AtomicAdd(&SDL_IMMDevice_DefaultCaptureGeneration, 1);
	}

	static SDL_WasapiDeviceEventHandler *playback_device_event_handler;
	static SDL_WasapiDeviceEventHandler *capture_device_event_handler;

	int WASAPI_PlatformInit(void)
	{
	SDL_AtomicSet(&SDL_IMMDevice_DefaultPlaybackGeneration, 1);
	SDL_AtomicSet(&SDL_IMMDevice_DefaultCaptureGeneration, 1);
	return 0;
	}

	void WASAPI_PlatformDeinit(void)
	{
	DevIdList *devidlist;
	DevIdList *next;

	delete playback_device_event_handler;
	playback_device_event_handler = nullptr;
	delete capture_device_event_handler;
	capture_device_event_handler = nullptr;

	for (devidlist = deviceid_list; devidlist; devidlist = next) {
	next = devidlist->next;
	SDL_free(devidlist->str);
	SDL_free(devidlist);
	}
	deviceid_list = NULL;
	}

	void WASAPI_EnumerateEndpoints(void)
	{
	// DeviceWatchers will fire an Added event for each existing device at
	// startup, so we don't need to enumerate them separately before
	// listening for updates.
	playback_device_event_handler = new SDL_WasapiDeviceEventHandler(SDL_FALSE);
	capture_device_event_handler = new SDL_WasapiDeviceEventHandler(SDL_TRUE);
	SDL_SemWait(playback_device_event_handler->completed);
	SDL_SemWait(capture_device_event_handler->completed);
	}

	struct SDL_WasapiActivationHandler : public RuntimeClass<RuntimeClassFlags<ClassicCom>, FtmBase, IActivateAudioInterfaceCompletionHandler>
	{
	SDL_WasapiActivationHandler() : device(nullptr) {}
	STDMETHOD(ActivateCompleted)
	(IActivateAudioInterfaceAsyncOperation *operation);
	SDL_AudioDevice *device;
	};

	HRESULT
	SDL_WasapiActivationHandler::ActivateCompleted(IActivateAudioInterfaceAsyncOperation *async)
	{
	// Just set a flag, since we're probably in a different thread. We'll pick it up and init everything on our own thread to prevent races.
	SDL_AtomicSet(&device->hidden->just_activated, 1);
	WASAPI_UnrefDevice(device);
	return S_OK;
	}

	void WASAPI_PlatformDeleteActivationHandler(void *handler)
	{
	((SDL_WasapiActivationHandler *)handler)->Release();
	}

	int WASAPI_GetDefaultAudioInfo(char *name, SDL_AudioSpec spec, int iscapture)
	{
	return SDL_Unsupported();
	}

	int WASAPI_ActivateDevice(_THIS, const SDL_bool isrecovery)
	{
	LPCWSTR devid = _this->hidden->devid;
	Platform::String ^ defdevid;

	if (devid == nullptr) {
	defdevid = _this->iscapture ? MediaDevice::GetDefaultAudioCaptureId(AudioDeviceRole::Default) : MediaDevice::GetDefaultAudioRenderId(AudioDeviceRole::Default);
	if (defdevid) {
	devid = defdevid->Data();
	}
	}

	SDL_AtomicSet(&_this->hidden->just_activated, 0);

	ComPtr<SDL_WasapiActivationHandler> handler = Make<SDL_WasapiActivationHandler>();
	if (handler == nullptr) {
	return SDL_SetError("Failed to allocate WASAPI activation handler");
	}

	handler.Get()->AddRef(); // we hold a reference after ComPtr destructs on return, causing a Release, and Release ourselves in WASAPI_PlatformDeleteActivationHandler(), etc.
	handler.Get()->device = _this;
	_this->hidden->activation_handler = handler.Get();

	WASAPI_RefDevice(_this); /* completion handler will unref it. */
	IActivateAudioInterfaceAsyncOperation *async = nullptr;
	const HRESULT ret = ActivateAudioInterfaceAsync(devid, __uuidof(IAudioClient), nullptr, handler.Get(), &async);

	if (FAILED(ret) \|\| async == nullptr) {
	if (async != nullptr) {
	async->Release();
	}
	handler.Get()->Release();
	WASAPI_UnrefDevice(_this);
	return WIN_SetErrorFromHRESULT("WASAPI can't activate requested audio endpoint", ret);
	}

	/* Spin until the async operation is complete.
	* If we don't PrepDevice before leaving this function, the bug list gets LONG:
	* - device.spec is not filled with the correct information
	* - The 'obtained' spec will be wrong for ALLOW_CHANGE properties
	* - SDL_AudioStreams will/will not be allocated at the right time
	* - SDL_assert(device->callbackspec.size == device->spec.size) will fail
	* - When the assert is ignored, skipping or a buffer overflow will occur
	*/
	while (!SDL_AtomicCAS(&_this->hidden->just_activated, 1, 0)) {
	SDL_Delay(1);
	}

	HRESULT activateRes = S_OK;
	IUnknown *iunknown = nullptr;
	const HRESULT getActivateRes = async->GetActivateResult(&activateRes, &iunknown);
	async->Release();
	if (FAILED(getActivateRes)) {
	return WIN_SetErrorFromHRESULT("Failed to get WASAPI activate result", getActivateRes);
	} else if (FAILED(activateRes)) {
	return WIN_SetErrorFromHRESULT("Failed to activate WASAPI device", activateRes);
	}

	iunknown->QueryInterface(IID_PPV_ARGS(&_this->hidden->client));
	if (!_this->hidden->client) {
	return SDL_SetError("Failed to query WASAPI client interface");
	}

	if (WASAPI_PrepDevice(_this, isrecovery) == -1) {
	return -1;
	}

	return 0;
	}

	void WASAPI_PlatformThreadInit(_THIS)
	{
	// !!! FIXME: set this thread to "Pro Audio" priority.
	}

	void WASAPI_PlatformThreadDeinit(_THIS)
	{
	// !!! FIXME: set this thread to "Pro Audio" priority.
	}

	/* Everything below was copied from SDL_wasapi.c, before it got moved to SDL_immdevice.c! */

	static const GUID SDL_KSDATAFORMAT_SUBTYPE_PCM = { 0x00000001, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };
	static const GUID SDL_KSDATAFORMAT_SUBTYPE_IEEE_FLOAT = { 0x00000003, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };

	extern "C" SDL_AudioFormat
	WaveFormatToSDLFormat(WAVEFORMATEX *waveformat)
	{
	if ((waveformat->wFormatTag == WAVE_FORMAT_IEEE_FLOAT) && (waveformat->wBitsPerSample == 32)) {
	return AUDIO_F32SYS;
	} else if ((waveformat->wFormatTag == WAVE_FORMAT_PCM) && (waveformat->wBitsPerSample == 16)) {
	return AUDIO_S16SYS;
	} else if ((waveformat->wFormatTag == WAVE_FORMAT_PCM) && (waveformat->wBitsPerSample == 32)) {
	return AUDIO_S32SYS;
	} else if (waveformat->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
	const WAVEFORMATEXTENSIBLE ext = (const WAVEFORMATEXTENSIBLE )waveformat;
	if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_IEEE_FLOAT, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 32)) {
	return AUDIO_F32SYS;
	} else if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_PCM, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 16)) {
	return AUDIO_S16SYS;
	} else if ((SDL_memcmp(&ext->SubFormat, &SDL_KSDATAFORMAT_SUBTYPE_PCM, sizeof(GUID)) == 0) && (waveformat->wBitsPerSample == 32)) {
	return AUDIO_S32SYS;
	}
	}
	return 0;
	}

	static void WASAPI_RemoveDevice(const SDL_bool iscapture, LPCWSTR devid)
	{
	DevIdList *i;
	DevIdList *next;
	DevIdList *prev = NULL;
	for (i = deviceid_list; i; i = next) {
	next = i->next;
	if (SDL_wcscmp(i->str, devid) == 0) {
	if (prev) {
	prev->next = next;
	} else {
	deviceid_list = next;
	}
	SDL_RemoveAudioDevice(iscapture, i->str);
	SDL_free(i->str);
	SDL_free(i);
	} else {
	prev = i;
	}
	}
	}

	static void WASAPI_AddDevice(const SDL_bool iscapture, const char devname, WAVEFORMATEXTENSIBLE fmt, LPCWSTR devid)
	{
	DevIdList *devidlist;
	SDL_AudioSpec spec;

	/* You can have multiple endpoints on a device that are mutually exclusive ("Speakers" vs "Line Out" or whatever).
	In a perfect world, things that are unplugged won't be in this collection. The only gotcha is probably for
	phones and tablets, where you might have an internal speaker and a headphone jack and expect both to be
	available and switch automatically. (!!! FIXME...?) */

	/* see if we already have this one. */
	for (devidlist = deviceid_list; devidlist; devidlist = devidlist->next) {
	if (SDL_wcscmp(devidlist->str, devid) == 0) {
	return; /* we already have this. */
	}
	}

	devidlist = (DevIdList )SDL_malloc(sizeof(devidlist));
	if (devidlist == NULL) {
	return; /* oh well. */
	}

	devid = SDL_wcsdup(devid);
	if (!devid) {
	SDL_free(devidlist);
	return; /* oh well. */
	}

	devidlist->str = (WCHAR *)devid;
	devidlist->next = deviceid_list;
	deviceid_list = devidlist;

	SDL_zero(spec);
	spec.channels = (Uint8)fmt->Format.nChannels;
	spec.freq = fmt->Format.nSamplesPerSec;
	spec.format = WaveFormatToSDLFormat((WAVEFORMATEX *)fmt);
	SDL_AddAudioDevice(iscapture, devname, &spec, (void *)devid);
	}

	#endif // SDL_AUDIO_DRIVER_WASAPI && defined(__WINRT__)

	/* vi: set ts=4 sw=4 expandtab: */