FFMPEG录屏（6）---- 获取音频设备列表（WASAPI）

继续使用WASAPI获取Windows系统音频设备列表

获取默认扬声器或麦克风

int device_audios::get_default(bool input, std::string & id, std::string & name)
{
	com_initialize com_obj;

	Microsoft::WRL::ComPtr<IMMDeviceEnumerator> device_enumerator = nullptr;
	Microsoft::WRL::ComPtr<IMMDevice> device = nullptr;
	Microsoft::WRL::ComPtr<IMMDeviceCollection> collection = nullptr;
	LPWSTR current_device_id = NULL;

	std::shared_ptr<void> raii_ptr(nullptr, [&](void*) {
		collection = nullptr;
		device = nullptr;
		device_enumerator = nullptr;
	});

	int ret = AE_NO;
	do {

		HRESULT hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL,
			__uuidof(IMMDeviceEnumerator), (void**)device_enumerator.GetAddressOf());
		if (FAILED(hr)) {
			ret = AE_CO_CREATE_FAILED;
			break;
		}

		hr = device_enumerator->GetDefaultAudioEndpoint(input == true ? eCapture : eRender, eConsole, device.GetAddressOf());
		if (FAILED(hr)) {
			ret = AE_CO_GETENDPOINT_FAILED;
			break;
		}

		hr = device_enumerator->EnumAudioEndpoints(input == true ? eCapture : eRender, DEVICE_STATE_ACTIVE, collection.GetAddressOf());
		if (FAILED(hr)) {
			ret = AE_CO_ENUMENDPOINT_FAILED;
			break;
		}

		UINT count;
		hr = collection->GetCount(&count);
		if (FAILED(hr)) {
			ret = AE_CO_GET_ENDPOINT_COUNT_FAILED;
			break;
		}

		hr = device->GetId(&current_device_id);
		if (FAILED(hr)) {
			ret = AE_CO_GET_ENDPOINT_ID_FAILED;
			break;
		}

		id = utils_string::unicode_utf8(current_device_id);

		CoTaskMemFree(current_device_id);

		IPropertyStore *pPropertyStore = NULL;
		PROPVARIANT pv;
		PropVariantInit(&pv);

		hr = device->OpenPropertyStore(STGM_READ, &pPropertyStore);
		if (FAILED(hr)) {
			ret = AE_CO_OPEN_PROPERTY_FAILED;
			break;
		}

		hr = pPropertyStore->GetValue(PKEY_Device_FriendlyName, &pv);
		if (FAILED(hr)) {
			ret = AE_CO_GET_VALUE_FAILED;
			break;
		}

		if (pv.vt == VT_LPWSTR) {
			name = utils_string::unicode_utf8(pv.pwszVal);
		}
		else if (pv.vt == VT_LPSTR) {
			name = utils_string::ascii_utf8(pv.pszVal);
		}

		PropVariantClear(&pv);
	} while (0);


	if (ret != AE_NO)
		al_debug("get_devices failed(%ld): %s", GetLastError(), err2str(ret));

	return ret;
}

获取扬声器或麦克风列表

int device_audios::get_devices(bool input, std::list<DEVICE_AUDIOS>& devices)
{
	com_initialize com_obj;

	devices.clear();

	Microsoft::WRL::ComPtr<IMMDeviceEnumerator> device_enumerator = nullptr;
	Microsoft::WRL::ComPtr<IMMDevice> device = nullptr;
	Microsoft::WRL::ComPtr<IMMDeviceCollection> collection = nullptr;
	LPWSTR current_device_id = NULL;

	int ret = AE_NO;

	do {
		std::shared_ptr<void> raii_ptr(nullptr, [&](void*) {
			collection = nullptr;
			device = nullptr;
			device_enumerator = nullptr;
		});

		HRESULT hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL,
			__uuidof(IMMDeviceEnumerator), (void**)device_enumerator.GetAddressOf());

		if (FAILED(hr)) {
			ret = AE_CO_CREATE_FAILED;
			break;
		}

		hr = device_enumerator->GetDefaultAudioEndpoint(input == true ? eCapture : eRender, eConsole, device.GetAddressOf());
		if (FAILED(hr)) {
			ret = AE_CO_GETENDPOINT_FAILED;
			break;
		}

		hr = device_enumerator->EnumAudioEndpoints(input == true ? eCapture : eRender, DEVICE_STATE_ACTIVE, collection.GetAddressOf());
		if (FAILED(hr)) {
			ret = AE_CO_ENUMENDPOINT_FAILED;
			break;
		}

		UINT count;
		hr = collection->GetCount(&count);
		if (FAILED(hr)) {
			ret = AE_CO_GET_ENDPOINT_COUNT_FAILED;
			break;
		}

		hr = device->GetId(&current_device_id);
		if (FAILED(hr)) {
			ret = AE_CO_GET_ENDPOINT_ID_FAILED;
			break;
		}

		std::string default_id = utils_string::unicode_utf8(current_device_id);

		CoTaskMemFree(current_device_id);

		for (int i = 0; i < count; ++i) {
			IMMDevice* pEndpointDevice = NULL;
			IDeviceTopology* deviceTopology = NULL;
			IConnector* connector = NULL;

			IPropertyStore *pPropertyStore = NULL;
			PROPVARIANT pv;
			PropVariantInit(&pv);

			LPWSTR device_name = NULL;
			LPWSTR device_id = NULL;

			std::string str_name, str_id, str_friendly;

			hr = collection->Item(i, &pEndpointDevice);
			if (FAILED(hr)) continue;

			/*hr = pEndpointDevice->Activate(__uuidof(IDeviceTopology), CLSCTX_INPROC_SERVER, NULL,
				(LPVOID*)&deviceTopology);
			hr = deviceTopology->GetConnector(0, &connector);

			hr = connector->GetConnectorIdConnectedTo(&device_name);

			str_name = utils_string::unicode_utf8(device_name);*/

			hr = pEndpointDevice->GetId(&device_id);
			if (FAILED(hr)) continue;

			str_id = utils_string::unicode_utf8(device_id);

			hr = pEndpointDevice->OpenPropertyStore(STGM_READ, &pPropertyStore);
			if (FAILED(hr)) continue;

			hr = pPropertyStore->GetValue(PKEY_Device_FriendlyName, &pv);
			if (FAILED(hr)) {
				PropVariantClear(&pv);
				continue;
			}

			if (pv.vt == VT_LPWSTR) {
				str_friendly = utils_string::unicode_utf8(pv.pwszVal);
			}
			else if (pv.vt == VT_LPSTR) {
				str_friendly = utils_string::ascii_utf8(pv.pszVal);
			}

			devices.push_back({
				str_id,
				str_friendly,
				str_id.compare(default_id) == 0
			});

			PropVariantClear(&pv);
			CoTaskMemFree(device_name);
			CoTaskMemFree(device_id);
		}
	} while (0);

	//insert a default device both name and id 'Default'
	if (ret == AE_NO && devices.size()) {
		devices.push_front({
			utils_string::ascii_utf8(DEFAULT_AUDIO_INOUTPUT_ID),
			utils_string::ascii_utf8(DEFAULT_AUDIO_INOUTPUT_NAME),
			true
		});
	}


	if (ret != AE_NO)
		al_debug("get_devices failed(%ld): %s", GetLastError(), err2str(ret));

	return ret;
}

需要注意的是，为了和FFMpeg保持一致，所有字符串传递均采用utf8编码，所以获取设备信息时均通过ascii_utf8函数进行了转换

GitHub传送门

screen-recorder