libobs/media-io: Remove 'volume' from audio_data (skip)

(Note: This commit breaks libobs compilation.  Skip if bisecting)

This variable is somewhat redundant.  Volume is already known/accessible
to front-ends.

libobs/media-io/audio-io.c

@@ -152,7 +152,6 @@ static inline void do_audio_output(struct audio_output *audio,
 
 	data.frames = frames;
 	data.timestamp = timestamp;
-	data.volume = 1.0f;
 
 	pthread_mutex_lock(&audio->input_mutex);
 

libobs/media-io/audio-io.h

@@ -69,7 +69,6 @@ struct audio_data {
 	uint8_t             *data[MAX_AV_PLANES];
 	uint32_t            frames;
 	uint64_t            timestamp;
-	float               volume;
 };
 
 struct audio_output_data {

libobs/obs-source.c

@@ -1001,9 +1001,6 @@ static void source_output_audio_data(obs_source_t *source,
 		conv_frames_to_time(sample_rate, in.frames);
 
 	in.timestamp += source->timing_adjust + source->sync_offset;
-	in.volume = source->base_volume * source->user_volume *
-		source->present_volume * obs->audio.user_volume *
-		obs->audio.present_volume;
 
 	if (source->next_audio_sys_ts_min == in.timestamp)
 		push_back = true;
@@ -1027,9 +1024,6 @@ static void source_output_audio_data(obs_source_t *source,
 			(source->push_to_mute_enabled && push_to_mute_active) ||
 			(source->push_to_talk_enabled && !push_to_talk_active);
 
-	if (muted)
-		in.volume = 0.0f;
-
 	pthread_mutex_lock(&source->audio_buf_mutex);
 
 	if (push_back)