Corrections to audio buffer size calculations

2 files changed, 20 insertions, 11 deletions

diff --git a/platform/osx/audio_driver_osx.cpp b/platform/osx/audio_driver_osx.cpp
index 8c5a734f76..78c52af201 100644
--- a/platform/osx/audio_driver_osx.cpp
+++ b/platform/osx/audio_driver_osx.cpp
@@ -77,7 +77,7 @@ Error AudioDriverOSX::initDevice() {
 			break;
 	}*/
 
-	mix_rate = GLOBAL_DEF("audio/mix_rate", 44100);
+	mix_rate = GLOBAL_DEF("audio/mix_rate", DEFAULT_MIX_RATE);
 
 	zeromem(&strdesc, sizeof(strdesc));
 	strdesc.mFormatID = kAudioFormatLinearPCM;
@@ -92,15 +92,19 @@ Error AudioDriverOSX::initDevice() {
 	result = AudioUnitSetProperty(audio_unit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &strdesc, sizeof(strdesc));
 	ERR_FAIL_COND_V(result != noErr, FAILED);
 
-	int latency = GLOBAL_DEF("audio/output_latency", 25);
-	unsigned int buffer_size = closest_power_of_2(latency * mix_rate / 1000);
+	int latency = GLOBAL_DEF("audio/output_latency", DEFAULT_OUTPUT_LATENCY);
+	// Sample rate is independent of channels (ref: https://stackoverflow.com/questions/11048825/audio-sample-frequency-rely-on-channels)
+	buffer_frames = closest_power_of_2(latency * mix_rate / 1000);
 
-	if (OS::get_singleton()->is_stdout_verbose()) {
-		print_line("audio buffer size: " + itos(buffer_size) + " calculated latency: " + itos(buffer_size * 1000 / mix_rate));
-	}
+	result = AudioUnitSetProperty(audio_unit, kAudioDevicePropertyBufferFrameSize, kAudioUnitScope_Global, kOutputBus, &buffer_frames, sizeof(UInt32));
+	ERR_FAIL_COND_V(result != noErr, FAILED);
 
+	buffer_size = buffer_frames * channels;
 	samples_in.resize(buffer_size);
-	buffer_frames = buffer_size / channels;
+
+	if (OS::get_singleton()->is_stdout_verbose()) {
+		print_line("audio buffer frames: " + itos(buffer_frames) + " calculated latency: " + itos(buffer_frames * 1000 / mix_rate) + "ms");
+	}
 
 	AURenderCallbackStruct callback;
 	zeromem(&callback, sizeof(AURenderCallbackStruct));
@@ -234,7 +238,7 @@ void AudioDriverOSX::start() {
 };
 
 int AudioDriverOSX::get_mix_rate() const {
-	return 44100;
+	return mix_rate;
 };
 
 AudioDriver::SpeakerMode AudioDriverOSX::get_speaker_mode() const {
@@ -282,8 +286,12 @@ AudioDriverOSX::AudioDriverOSX() {
 	active = false;
 	mutex = NULL;
 
-	mix_rate = 44100;
+	mix_rate = 0;
 	channels = 2;
+
+	buffer_size = 0;
+	buffer_frames = 0;
+
 	samples_in.clear();
 };
 
diff --git a/platform/osx/audio_driver_osx.h b/platform/osx/audio_driver_osx.h
index ac178b89f3..a7e68c8141 100644
--- a/platform/osx/audio_driver_osx.h
+++ b/platform/osx/audio_driver_osx.h
@@ -45,8 +45,9 @@ class AudioDriverOSX : public AudioDriver {
 	Mutex *mutex;
 
 	int mix_rate;
-	int channels;
-	int buffer_frames;
+	unsigned int channels;
+	unsigned int buffer_frames;
+	unsigned int buffer_size;
 
 	Vector<int32_t> samples_in;