Create IXAudio2MasteringVoice from IMMDevice

xaudioDevice.cpp

IXAudio2MasteringVoice* createVoiceForDevice(IXAudio2* xaudio2, IMMDevice* device)
{
	LPWSTR id;
	HRESULT hr = device->GetId(&id);
	if (FAILED(hr))
	{
		device->Release();
		return nullptr;
	}

	// build the XAudio2 device id
	std::wstring deviceIdStr;
	deviceIdStr.reserve(112);
	deviceIdStr.append(L"\\\\?\\SWD#MMDEVAPI#");
	deviceIdStr.append(id);
	deviceIdStr.push_back(L'#');
	size_t offset = deviceIdStr.size();
	deviceIdStr.resize(deviceIdStr.capacity());
	StringFromGUID2(DEVINTERFACE_AUDIO_RENDER, &deviceIdStr[offset], (int)(deviceIdStr.size() - offset));

	CoTaskMemFree(id);
	device->Release();

	// create mastering voice
	IXAudio2MasteringVoice* masterVoice;
	hr = xaudio2->CreateMasteringVoice(&masterVoice, 2, XAUDIO2_DEFAULT_SAMPLERATE, 0, deviceIdStr.c_str(), nullptr, AudioCategory_GameEffects);
	if (FAILED(hr))
	{
		return nullptr;
	}

	return masterVoice;
}