From 22aa66a6eb520444c492f6a7c595fd7a5de98bdc Mon Sep 17 00:00:00 2001
From: jp9000 <obs.jim@gmail.com>
Date: Thu, 10 Oct 2019 01:54:37 -0700
Subject: [PATCH] libobs/audio-monitoring: Don't init until used

This prevents audio monitoring from actually initializing unless audio
is actually played back through the source.  This prevents many browser
sources from initializing audio monitoring all at once needlessly if
audio is not being rerouted to OBS.
---
 libobs/audio-monitoring/win32/wasapi-output.c | 80 ++++++++++++-------
 1 file changed, 52 insertions(+), 28 deletions(-)

diff --git a/libobs/audio-monitoring/win32/wasapi-output.c b/libobs/audio-monitoring/win32/wasapi-output.c
index d293f56fc..4ff53a6a9 100644
--- a/libobs/audio-monitoring/win32/wasapi-output.c
+++ b/libobs/audio-monitoring/win32/wasapi-output.c
@@ -33,6 +33,8 @@ struct audio_monitor {
 	uint32_t channels;
 	bool source_has_video;
 	bool ignore;
+	bool initialized;
+	bool failure;
 
 	int64_t lowest_audio_offset;
 	struct circlebuf delay_buffer;
@@ -131,11 +133,13 @@ static bool process_audio_delay(struct audio_monitor *monitor, float **data,
 	return false;
 }
 
+static void audio_monitor_start_device(struct audio_monitor *monitor);
+
 static void on_audio_playback(void *param, obs_source_t *source,
 			      const struct audio_data *audio_data, bool muted)
 {
 	struct audio_monitor *monitor = param;
-	IAudioRenderClient *render = monitor->render;
+	IAudioRenderClient *render;
 	uint8_t *resample_data[MAX_AV_PLANES];
 	float vol = source->user_volume;
 	uint32_t resample_frames;
@@ -149,6 +153,14 @@ static void on_audio_playback(void *param, obs_source_t *source,
 	if (os_atomic_load_long(&source->activate_refs) == 0) {
 		goto unlock;
 	}
+	if (!monitor->failure && !monitor->initialized) {
+		audio_monitor_start_device(monitor);
+	}
+	if (monitor->failure) {
+		goto unlock;
+	}
+
+	render = monitor->render;
 
 	success = audio_resampler_resample(
 		monitor->resampler, resample_data, &resample_frames, &ts_offset,
@@ -239,10 +251,7 @@ static enum speaker_layout convert_speaker_layout(DWORD layout, WORD channels)
 	return (enum speaker_layout)channels;
 }
 
-extern bool devices_match(const char *id1, const char *id2);
-
-static bool audio_monitor_init(struct audio_monitor *monitor,
-			       obs_source_t *source)
+static void audio_monitor_start_device(struct audio_monitor *monitor)
 {
 	IMMDeviceEnumerator *immde = NULL;
 	WAVEFORMATEX *wfex = NULL;
@@ -250,25 +259,9 @@ static bool audio_monitor_init(struct audio_monitor *monitor,
 	UINT32 frames;
 	HRESULT hr;
 
-	pthread_mutex_init_value(&monitor->playback_mutex);
-
-	monitor->source = source;
-
 	const char *id = obs->audio.monitoring_device_id;
 	if (!id) {
-		return false;
-	}
-
-	if (source->info.output_flags & OBS_SOURCE_DO_NOT_SELF_MONITOR) {
-		obs_data_t *s = obs_source_get_settings(source);
-		const char *s_dev_id = obs_data_get_string(s, "device_id");
-		bool match = devices_match(s_dev_id, id);
-		obs_data_release(s);
-
-		if (match) {
-			monitor->ignore = true;
-			return true;
-		}
+		goto fail;
 	}
 
 	/* ------------------------------------------ *
@@ -277,7 +270,7 @@ static bool audio_monitor_init(struct audio_monitor *monitor,
 	hr = CoCreateInstance(&CLSID_MMDeviceEnumerator, NULL, CLSCTX_ALL,
 			      &IID_IMMDeviceEnumerator, (void **)&immde);
 	if (FAILED(hr)) {
-		return false;
+		goto fail;
 	}
 
 	if (strcmp(id, "default") == 0) {
@@ -356,22 +349,53 @@ static bool audio_monitor_init(struct audio_monitor *monitor,
 		goto fail;
 	}
 
-	if (pthread_mutex_init(&monitor->playback_mutex, NULL) != 0) {
-		goto fail;
-	}
-
 	hr = monitor->client->lpVtbl->Start(monitor->client);
 	if (FAILED(hr)) {
 		goto fail;
 	}
 
 	success = true;
+	monitor->initialized = true;
 
 fail:
+	if (!success)
+		monitor->failure = true;
+
 	safe_release(immde);
 	if (wfex)
 		CoTaskMemFree(wfex);
-	return success;
+}
+
+extern bool devices_match(const char *id1, const char *id2);
+
+static bool audio_monitor_init(struct audio_monitor *monitor,
+			       obs_source_t *source)
+{
+	pthread_mutex_init_value(&monitor->playback_mutex);
+
+	monitor->source = source;
+
+	const char *id = obs->audio.monitoring_device_id;
+	if (!id) {
+		return false;
+	}
+
+	if (pthread_mutex_init(&monitor->playback_mutex, NULL) != 0) {
+		return false;
+	}
+
+	if (source->info.output_flags & OBS_SOURCE_DO_NOT_SELF_MONITOR) {
+		obs_data_t *s = obs_source_get_settings(source);
+		const char *s_dev_id = obs_data_get_string(s, "device_id");
+		bool match = devices_match(s_dev_id, id);
+		obs_data_release(s);
+
+		if (match) {
+			monitor->ignore = true;
+		}
+	}
+
+	return true;
 }
 
 static void audio_monitor_init_final(struct audio_monitor *monitor)