1 files changed, 62 insertions, 38 deletions

diff --git a/drivers/rtaudio/audio_driver_rtaudio.cpp b/drivers/rtaudio/audio_driver_rtaudio.cpp
index 4b145c09fb..a798990449 100644
--- a/drivers/rtaudio/audio_driver_rtaudio.cpp
+++ b/drivers/rtaudio/audio_driver_rtaudio.cpp
@@ -47,9 +47,7 @@ const char* AudioDriverRtAudio::get_name() const {
 
 }
 
-// Two-channel sawtooth wave generator.
-int AudioDriverRtAudio::callback( void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames,
-	double streamTime, RtAudioStreamStatus status, void *userData ) {
+int AudioDriverRtAudio::callback( void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames, double streamTime, RtAudioStreamStatus status, void *userData ) {
 
 	if (status) {
 		if (status & RTAUDIO_INPUT_OVERFLOW) {
@@ -64,8 +62,6 @@ int AudioDriverRtAudio::callback( void *outputBuffer, void *inputBuffer, unsigne
 	AudioDriverRtAudio *self = (AudioDriverRtAudio*)userData;
 
 	if (self->mutex->try_lock()!=OK) {
-
-
 		// what should i do..
 		for(unsigned int i=0;i<nBufferFrames;i++)
 			buffer[i]=0;
@@ -100,61 +96,89 @@ Error AudioDriverRtAudio::init() {
 	else
 		output_format=OUTPUT_STEREO;
 
-
 	RtAudio::StreamParameters parameters;
 	parameters.deviceId = dac->getDefaultOutputDevice();
 	RtAudio::StreamOptions options;
+
+	// set the desired numberOfBuffers
+	unsigned int target_number_of_buffers = 4;
+	options.numberOfBuffers = target_number_of_buffers;
+
 //	options.
 //	RtAudioStreamFlags flags;      /*!< A bit-mask of stream flags (RTAUDIO_NONINTERLEAVED, RTAUDIO_MINIMIZE_LATENCY, RTAUDIO_HOG_DEVICE). *///
 //	unsigned int numberOfBuffers;  /*!< Number of stream buffers. */
 //	std::string streamName;        /*!< A stream name (currently used only in Jack). */
 //	int priority;                  /*!< Scheduling priority of callback thread (only used with flag RTAUDIO_SCHEDULE_REALTIME). */
 
-
 	parameters.firstChannel = 0;
 	mix_rate = GLOBAL_DEF("audio/mix_rate",44100);
 
 	int latency = GLOBAL_DEF("audio/output_latency",25);
-	unsigned int buffer_size = nearest_power_of_2( latency * mix_rate / 1000 );
+	// calculate desired buffer_size, taking the desired numberOfBuffers into account (latency depends on numberOfBuffers*buffer_size)
+	unsigned int buffer_size = nearest_power_of_2( latency * mix_rate / 1000 / target_number_of_buffers);
+
 	if (OS::get_singleton()->is_stdout_verbose()) {
 		print_line("audio buffer size: "+itos(buffer_size));
 	}
 
-//	bool success=false;
-
-	while( true) {
-
-		switch(output_format) {
-
-			case OUTPUT_MONO: parameters.nChannels = 1; break;
-			case OUTPUT_STEREO: parameters.nChannels = 2; break;
-			case OUTPUT_QUAD: parameters.nChannels = 4; break;
-			case OUTPUT_5_1: parameters.nChannels = 6; break;
-		};
+	short int tries = 2;
 
+	while(true) {
+		while( true) {
+			switch(output_format) {
+				case OUTPUT_MONO: parameters.nChannels = 1; break;
+				case OUTPUT_STEREO: parameters.nChannels = 2; break;
+				case OUTPUT_QUAD: parameters.nChannels = 4; break;
+				case OUTPUT_5_1: parameters.nChannels = 6; break;
+			};
 
-		try {
-			dac->openStream( &parameters, NULL, RTAUDIO_SINT32,
-			    mix_rate, &buffer_size, &callback, this,&options );
-			mutex = Mutex::create(true);
-			active=true;
+			try {
+				dac->openStream( &parameters, NULL, RTAUDIO_SINT32, mix_rate, &buffer_size, &callback, this,&options );
+				mutex = Mutex::create(true);
+				active=true;
+
+				break;
+			} catch ( RtAudioError& e ) {
+				// try with less channels
+				ERR_PRINT("Unable to open audio, retrying with fewer channels..");
+
+				switch(output_format) {
+					case OUTPUT_MONO: ERR_EXPLAIN("Unable to open audio."); ERR_FAIL_V( ERR_UNAVAILABLE ); break;
+					case OUTPUT_STEREO: output_format=OUTPUT_MONO; break;
+					case OUTPUT_QUAD: output_format=OUTPUT_STEREO; break;
+					case OUTPUT_5_1: output_format=OUTPUT_QUAD; break;
+				};
+			}
+		}
 
+		// compare actual numberOfBuffers with the desired one. If not equal, close and reopen the stream with adjusted buffer size, so the desired output_latency is still correct
+		if(target_number_of_buffers != options.numberOfBuffers) {
+			if(tries <= 0) {
+				ERR_EXPLAIN("RtAudio: Unable to set correct number of buffers.");
+				ERR_FAIL_V( ERR_UNAVAILABLE ); 
+				break;
+			}
+			
+			try {
+				dac->closeStream();
+			} catch ( RtAudioError& e ) {
+				ERR_PRINT(e.what());
+				ERR_FAIL_V( ERR_UNAVAILABLE );
+				break;
+			}
+			if (OS::get_singleton()->is_stdout_verbose()) 
+				print_line("RtAudio: Desired number of buffers (" + itos(target_number_of_buffers) + ") not available. Using " + itos(options.numberOfBuffers) + " instead. Reopening stream with adjusted buffer_size.");
+
+			// new buffer size dependent on the ratio between set and actual numberOfBuffers
+			buffer_size = buffer_size / (options.numberOfBuffers / target_number_of_buffers);
+			target_number_of_buffers = options.numberOfBuffers;
+			tries--;
+		} else {
 			break;
-        } catch ( RtAudioError& e ) {
-			// try with less channels
-
-			ERR_PRINT("Unable to open audio, retrying with fewer channels..");
-
-			switch(output_format) {
-
-				case OUTPUT_MONO: ERR_EXPLAIN("Unable to open audio."); ERR_FAIL_V( ERR_UNAVAILABLE ); break;
-				case OUTPUT_STEREO: output_format=OUTPUT_MONO; break;
-				case OUTPUT_QUAD: output_format=OUTPUT_STEREO; break;
-				case OUTPUT_5_1: output_format=OUTPUT_QUAD; break;
-			};
 		}
-	}
+			
 
+	}
 
 	return OK;
 }
@@ -190,7 +214,6 @@ void AudioDriverRtAudio::unlock() {
 
 void AudioDriverRtAudio::finish() {
 
-
 	 if ( active && dac->isStreamOpen() )
 		 dac->closeStream();
 	 if (mutex)
@@ -203,6 +226,7 @@ void AudioDriverRtAudio::finish() {
 
 AudioDriverRtAudio::AudioDriverRtAudio()
 {
+
 	mutex=NULL;
 	mix_rate=44100;
 	output_format=OUTPUT_STEREO;