Revert libobs: Mix audio of each source in a scene only once

This reverts commit: 8a38e33 [1].
This also reverts commit: 72924ac [2].
(in favour of a fix in core audio pipeline, which allows to address
edge cases).

[1] libobs: Mix audio of each source in a scene only once
https://github.com/obsproject/obs-studio/commit/8a38e3375b63692b01e5088d37f531f36a5d39f9
[2] libobs: Deduplicate audio for nested scenes/groups if not
transitioning
https://github.com/obsproject/obs-studio/commit/72924ac1f3c4c55de038fe1f03a0e197a155d5e7

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

libobs/obs-scene.c

@@ -237,7 +237,6 @@ static void scene_destroy(void *data)
 
 	pthread_mutex_destroy(&scene->video_mutex);
 	pthread_mutex_destroy(&scene->audio_mutex);
-	da_free(scene->mix_sources);
 	bfree(scene);
 }
 
@@ -1611,26 +1610,14 @@ static inline void mix_audio(float *p_out, float *p_in, size_t pos, size_t count
 		*(out++) += *(in++);
 }
 
-static inline struct scene_source_mix *get_source_mix(struct obs_scene *scene, struct obs_source *source)
-{
-	for (size_t i = 0; i < scene->mix_sources.num; i++) {
-		struct scene_source_mix *mix = &scene->mix_sources.array[i];
-		if (mix->source == source)
-			return mix;
-	}
-
-	return NULL;
-}
-
-static bool scene_audio_render_internal(struct obs_scene *scene, struct obs_scene *parent, uint64_t *ts_out,
-					struct obs_source_audio_mix *audio_output, uint32_t mixers, size_t channels,
-					size_t sample_rate, float *parent_buf)
+static bool scene_audio_render(void *data, uint64_t *ts_out, struct obs_source_audio_mix *audio_output, uint32_t mixers,
+			       size_t channels, size_t sample_rate)
 {
 	uint64_t timestamp = 0;
 	float buf[AUDIO_OUTPUT_FRAMES];
 	struct obs_source_audio_mix child_audio;
+	struct obs_scene *scene = data;
 	struct obs_scene_item *item;
-	struct obs_scene *mix_scene = parent ? parent : scene;
 
 	audio_lock(scene);
 
@@ -1671,9 +1658,9 @@ static bool scene_audio_render_internal(struct obs_scene *scene, struct obs_scen
 	while (item) {
 		uint64_t source_ts;
 		size_t pos;
+		size_t count;
 		bool apply_buf;
 		struct obs_source *source;
-		struct scene_source_mix *source_mix;
 
 		if (item->visible && transition_active(item->show_transition))
 			source = item->show_transition;
@@ -1702,80 +1689,14 @@ static bool scene_audio_render_internal(struct obs_scene *scene, struct obs_scen
 			continue;
 		}
 
-		if (!apply_buf && !item->visible && !transition_active(item->hide_transition)) {
-			item = item->next;
-			continue;
-		}
-
-		size_t count = AUDIO_OUTPUT_FRAMES - pos;
-
-		/* Update buf so that parent mute state applies to all current
-		 * scene items as well */
-		if (parent_buf && (!apply_buf || memcmp(buf, parent_buf, sizeof(float) * count) != 0)) {
-			for (size_t i = 0; i < count; i++) {
-				if (!apply_buf) {
-					buf[i] = parent_buf[i];
-				} else {
-					buf[i] = buf[i] < parent_buf[i] ? buf[i] : parent_buf[i];
-				}
-			}
+		count = AUDIO_OUTPUT_FRAMES - pos;
 
-			apply_buf = true;
-		}
-
-		/* If "source" is a group/scene and has no transition,
-		 * add their items to the current list */
-		if (source == item->source && (obs_source_is_group(source) || obs_source_is_scene(source))) {
-			scene_audio_render_internal(source->context.data, mix_scene, NULL, NULL, 0, 0, sample_rate,
-						    apply_buf ? buf : NULL);
+		if (!apply_buf && !item->visible && !transition_active(item->hide_transition)) {
 			item = item->next;
 			continue;
 		}
 
-		source_mix = get_source_mix(mix_scene, item->source);
-
-		if (!source_mix) {
-			source_mix = da_push_back_new(mix_scene->mix_sources);
-			source_mix->source = item->source;
-			source_mix->transition = source != item->source ? source : NULL;
-			source_mix->apply_buf = apply_buf;
-			source_mix->pos = pos;
-			source_mix->count = count;
-			if (apply_buf) {
-				memcpy(source_mix->buf, buf, sizeof(float) * source_mix->count);
-			}
-		} else {
-			/* Only transition audio if there are no
-			 * non-transitioning scene items. */
-			if (source_mix->transition && source == item->source)
-				source_mix->transition = NULL;
-			/* Only apply buf to mix if all scene items for this
-			 * source require it. */
-			source_mix->apply_buf = source_mix->apply_buf && apply_buf;
-			/* Update buf so that only highest value across all
-			 * items is used. */
-			if (source_mix->apply_buf &&
-			    memcmp(source_mix->buf, buf, source_mix->count * sizeof(float)) != 0) {
-				for (size_t i = 0; i < source_mix->count; i++) {
-					if (buf[i] > source_mix->buf[i])
-						source_mix->buf[i] = buf[i];
-				}
-			}
-		}
-
-		item = item->next;
-	}
-
-	if (!audio_output) {
-		audio_unlock(scene);
-		return true;
-	}
-
-	for (size_t i = 0; i < scene->mix_sources.num; i++) {
-		struct scene_source_mix *source_mix = &scene->mix_sources.array[i];
-		obs_source_get_audio_mix(source_mix->transition ? source_mix->transition : source_mix->source,
-					 &child_audio);
-
+		obs_source_get_audio_mix(source, &child_audio);
 		for (size_t mix = 0; mix < MAX_AUDIO_MIXES; mix++) {
 			if ((mixers & (1 << mix)) == 0)
 				continue;
@@ -1783,31 +1704,21 @@ static bool scene_audio_render_internal(struct obs_scene *scene, struct obs_scen
 			for (size_t ch = 0; ch < channels; ch++) {
 				float *out = audio_output->output[mix].data[ch];
 				float *in = child_audio.output[mix].data[ch];
-
-				if (source_mix->apply_buf)
-					mix_audio_with_buf(out, in, source_mix->buf, source_mix->pos,
-							   source_mix->count);
+				if (apply_buf)
+					mix_audio_with_buf(out, in, buf, pos, count);
 				else
-					mix_audio(out, in, source_mix->pos, source_mix->count);
+					mix_audio(out, in, pos, count);
 			}
 		}
+		item = item->next;
 	}
 
-	da_clear(scene->mix_sources);
-
 	*ts_out = timestamp;
 	audio_unlock(scene);
 
 	return true;
 }
 
-static bool scene_audio_render(void *data, uint64_t *ts_out, struct obs_source_audio_mix *audio_output, uint32_t mixers,
-			       size_t channels, size_t sample_rate)
-{
-	struct obs_scene *scene = data;
-	return scene_audio_render_internal(scene, NULL, ts_out, audio_output, mixers, channels, sample_rate, NULL);
-}
-
 enum gs_color_space scene_video_get_color_space(void *data, size_t count, const enum gs_color_space *preferred_spaces)
 {
 	UNUSED_PARAMETER(data);

libobs/obs-scene.h

@@ -96,15 +96,6 @@ struct obs_scene_item {
 	struct obs_scene_item *next;
 };
 
-struct scene_source_mix {
-	obs_source_t *source;
-	obs_source_t *transition;
-	size_t pos;
-	size_t count;
-	bool apply_buf;
-	float buf[AUDIO_OUTPUT_FRAMES];
-};
-
 struct obs_scene {
 	struct obs_source *source;
 
@@ -122,6 +113,4 @@ struct obs_scene {
 	pthread_mutex_t video_mutex;
 	pthread_mutex_t audio_mutex;
 	struct obs_scene_item *first_item;
-
-	DARRAY(struct scene_source_mix) mix_sources;
 };