Properly deal with clicking on audio stream change or stop (AudioStreamPlayer only)

(cherry picked from commit 040b59c010)

scene/audio/audio_stream_player.cpp

@@ -32,10 +32,41 @@
 
 #include "core/engine.h"
 
-void AudioStreamPlayer::_mix_internal(bool p_fadeout) {
+void AudioStreamPlayer::_mix_to_bus(const AudioFrame *p_frames, int p_amount) {
 
 	int bus_index = AudioServer::get_singleton()->thread_find_bus_index(bus);
 
+	AudioFrame *targets[4] = { NULL, NULL, NULL, NULL };
+
+	if (AudioServer::get_singleton()->get_speaker_mode() == AudioServer::SPEAKER_MODE_STEREO) {
+		targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 0);
+	} else {
+		switch (mix_target) {
+			case MIX_TARGET_STEREO: {
+				targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 0);
+			} break;
+			case MIX_TARGET_SURROUND: {
+				for (int i = 0; i < AudioServer::get_singleton()->get_channel_count(); i++) {
+					targets[i] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, i);
+				}
+			} break;
+			case MIX_TARGET_CENTER: {
+				targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 1);
+			} break;
+		}
+	}
+
+	for (int c = 0; c < 4; c++) {
+		if (!targets[c])
+			break;
+		for (int i = 0; i < p_amount; i++) {
+			targets[c][i] += p_frames[i];
+		}
+	}
+}
+
+void AudioStreamPlayer::_mix_internal(bool p_fadeout) {
+
 	//get data
 	AudioFrame *buffer = mix_buffer.ptrw();
 	int buffer_size = mix_buffer.size();
@@ -60,39 +91,18 @@ void AudioStreamPlayer::_mix_internal(bool p_fadeout) {
 	//set volume for next mix
 	mix_volume_db = target_volume;
 
-	AudioFrame *targets[4] = { NULL, NULL, NULL, NULL };
+	_mix_to_bus(buffer, buffer_size);
-
-	if (AudioServer::get_singleton()->get_speaker_mode() == AudioServer::SPEAKER_MODE_STEREO) {
-		targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 0);
-	} else {
-		switch (mix_target) {
-			case MIX_TARGET_STEREO: {
-				targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 0);
-			} break;
-			case MIX_TARGET_SURROUND: {
-				for (int i = 0; i < AudioServer::get_singleton()->get_channel_count(); i++) {
-					targets[i] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, i);
-				}
-			} break;
-			case MIX_TARGET_CENTER: {
-				targets[0] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(bus_index, 1);
-			} break;
-		}
-	}
-
-	for (int c = 0; c < 4; c++) {
-		if (!targets[c])
-			break;
-		for (int i = 0; i < buffer_size; i++) {
-			targets[c][i] += buffer[i];
-		}
-	}
 }
 
 void AudioStreamPlayer::_mix_audio() {
 
+	if (use_fadeout) {
+		_mix_to_bus(fadeout_buffer.ptr(), fadeout_buffer.size());
+		use_fadeout = false;
+	}
+
 	if (!stream_playback.is_valid() || !active ||
-			(stream_paused && !stream_fade)) {
+			(stream_paused && !stream_paused_fade)) {
 		return;
 	}
 
@@ -104,7 +114,11 @@ void AudioStreamPlayer::_mix_audio() {
 		return;
 	}
 
-	if (setseek >= 0.0) {
+	if (setstop) {
+		_mix_internal(true);
+		stream_playback->stop();
+		setstop = false;
+	} else if (setseek >= 0.0) {
 		if (stream_playback->is_playing()) {
 
 			//fade out to avoid pops
@@ -158,6 +172,28 @@ void AudioStreamPlayer::set_stream(Ref<AudioStream> p_stream) {
 
 	AudioServer::get_singleton()->lock();
 
+	if (active && stream_playback.is_valid() && !stream_paused) {
+		//changing streams out of the blue is not a great idea, but at least
+		//lets try to somehow avoid a click
+
+		AudioFrame *buffer = fadeout_buffer.ptrw();
+		int buffer_size = fadeout_buffer.size();
+
+		stream_playback->mix(buffer, pitch_scale, buffer_size);
+
+		//multiply volume interpolating to avoid clicks if this changes
+		float target_volume = -80.0;
+		float vol = Math::db2linear(mix_volume_db);
+		float vol_inc = (Math::db2linear(target_volume) - vol) / float(buffer_size);
+
+		for (int i = 0; i < buffer_size; i++) {
+			buffer[i] *= vol;
+			vol += vol_inc;
+		}
+
+		use_fadeout = true;
+	}
+
 	mix_buffer.resize(AudioServer::get_singleton()->thread_get_mix_buffer_size());
 
 	if (stream_playback.is_valid()) {
@@ -165,6 +201,7 @@ void AudioStreamPlayer::set_stream(Ref<AudioStream> p_stream) {
 		stream.unref();
 		active = false;
 		setseek = -1;
+		setstop = false;
 	}
 
 	if (p_stream.is_valid()) {
@@ -206,6 +243,7 @@ void AudioStreamPlayer::play(float p_from_pos) {
 	if (stream_playback.is_valid()) {
 		//mix_volume_db = volume_db; do not reset volume ramp here, can cause clicks
 		setseek = p_from_pos;
+		setstop = false;
 		active = true;
 		set_process_internal(true);
 	}
@@ -220,17 +258,15 @@ void AudioStreamPlayer::seek(float p_seconds) {
 
 void AudioStreamPlayer::stop() {
 
-	if (stream_playback.is_valid()) {
+	if (stream_playback.is_valid() && active) {
-		stream_playback->stop();
+		setstop = true;
-		active = false;
-		set_process_internal(false);
 	}
 }
 
 bool AudioStreamPlayer::is_playing() const {
 
 	if (stream_playback.is_valid()) {
-		return active; //&& stream_playback->is_playing();
+		return active && !setstop; //&& stream_playback->is_playing();
 	}
 
 	return false;
@@ -395,6 +431,9 @@ AudioStreamPlayer::AudioStreamPlayer() {
 	stream_paused = false;
 	stream_paused_fade = false;
 	mix_target = MIX_TARGET_STEREO;
+	fadeout_buffer.resize(512);
+	setstop = false;
+	use_fadeout = false;
 
 	AudioServer::get_singleton()->connect("bus_layout_changed", this, "_bus_layout_changed");
 }

scene/audio/audio_stream_player.h

@@ -49,9 +49,12 @@ private:
 	Ref<AudioStreamPlayback> stream_playback;
 	Ref<AudioStream> stream;
 	Vector<AudioFrame> mix_buffer;
+	Vector<AudioFrame> fadeout_buffer;
+	bool use_fadeout;
 
 	volatile float setseek;
 	volatile bool active;
+	volatile bool setstop;
 
 	float mix_volume_db;
 	float pitch_scale;
@@ -71,6 +74,7 @@ private:
 	bool _is_active() const;
 
 	void _bus_layout_changed();
+	void _mix_to_bus(const AudioFrame *p_frames, int p_amount);
 
 protected:
 	void _validate_property(PropertyInfo &property) const;
@@ -107,7 +111,6 @@ public:
 
 	Ref<AudioStreamPlayback> get_stream_playback();
 
-
 	AudioStreamPlayer();
 	~AudioStreamPlayer();
 };