win-wasapi: Store in source settings 'default_device_id'

This enables the new setting 'default_device_id' which is useful for
audio monitoring deduplication.
Currently only 'device_id' is stored; but no information about the real
device is known if 'device_id' is 'default'.
The 'default_device_id' is stored during creation of the source and is
updated whenever the user changes the default audio output device in
windows audio settings.

Signed-off-by: pkv <[email protected]>

Author: pkviet

plugins/win-wasapi/enum-wasapi.cpp

@@ -90,3 +90,40 @@ void GetWASAPIAudioDevices(vector<AudioDeviceInfo> &devices, bool input)
 		blog(LOG_WARNING, "[GetWASAPIAudioDevices] %s: %lX", error.str, error.hr);
 	}
 }
+
+bool GetDefaultOuputDeviceId(char **out_id)
+{
+	HRESULT hr;
+	ComPtr<IMMDeviceEnumerator> enumerator;
+	IMMDevice *device = NULL;
+	LPWSTR w_id = NULL;
+	bool success = false;
+
+	*out_id = NULL;
+
+	hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL, __uuidof(IMMDeviceEnumerator),
+			      (void **)enumerator.Assign());
+	if (FAILED(hr))
+		return false;
+
+	hr = enumerator->GetDefaultAudioEndpoint(eRender, eConsole, &device);
+	if (FAILED(hr))
+		goto fail;
+
+	hr = device->GetId(&w_id);
+	if (FAILED(hr))
+		goto fail;
+
+	os_wcs_to_utf8_ptr((const wchar_t *)w_id, 0, out_id);
+
+	success = (*out_id != NULL);
+
+fail:
+	if (w_id)
+		CoTaskMemFree(w_id);
+	if (device)
+		device->Release();
+	if (enumerator)
+		enumerator->Release();
+	return success;
+}

plugins/win-wasapi/enum-wasapi.hpp

@@ -39,3 +39,4 @@ struct AudioDeviceInfo {
 
 std::string GetDeviceName(IMMDevice *device);
 void GetWASAPIAudioDevices(std::vector<AudioDeviceInfo> &devices, bool input);
+bool GetDefaultOuputDeviceId(char **out_id);

plugins/win-wasapi/win-wasapi.cpp

@@ -28,6 +28,7 @@ using namespace std;
 #define OPT_USE_DEVICE_TIMING "use_device_timing"
 #define OPT_WINDOW "window"
 #define OPT_PRIORITY "priority"
+#define OPT_DEFAULT_DEVICE_ID "default_device_id"
 
 WASAPINotify *GetNotify();
 static void GetWASAPIDefaults(obs_data_t *settings);
@@ -304,6 +305,15 @@ WASAPISource::WASAPISource(obs_data_t *settings, obs_source_t *source_, SourceTy
 			(PFN_ActivateAudioInterfaceAsync)GetProcAddress(mmdevapi_module, "ActivateAudioInterfaceAsync");
 	}
 
+	char *default_id = NULL;
+	if (GetDefaultOuputDeviceId(&default_id)) {
+		blog(LOG_DEBUG, "[WASAPI] Default output device ID resolved to: %s", default_id);
+		obs_data_set_string(settings, OPT_DEFAULT_DEVICE_ID, default_id);
+		bfree(default_id);
+	} else {
+		blog(LOG_WARNING, "[WASAPI] Failed to get default output device ID");
+	}
+
 	UpdateSettings(BuildUpdateParams(settings));
 	LogSettings();
 
@@ -1197,10 +1207,23 @@ void WASAPISource::SetDefaultDevice(EDataFlow flow, ERole role, LPCWSTR id)
 		if (default_id.compare(id) == 0)
 			return;
 		default_id = id;
+		char *default_device_id = nullptr;
+		os_wcs_to_utf8_ptr((const wchar_t *)id, 0, &default_device_id);
+		obs_data_t *s = obs_source_get_settings(source);
+		if (s) {
+			obs_data_set_string(s, OPT_DEFAULT_DEVICE_ID, default_device_id);
+			obs_data_release(s);
+		}
+		bfree(default_device_id);
 	} else {
 		if (default_id.empty())
 			return;
 		default_id.clear();
+		obs_data_t *s = obs_source_get_settings(source);
+		if (s) {
+			obs_data_set_string(s, OPT_DEFAULT_DEVICE_ID, NULL);
+			obs_data_release(s);
+		}
 	}
 
 	blog(LOG_INFO, "WASAPI: Default %s device changed", input ? "input" : "output");