mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-23 03:32:32 +00:00
Pulled away my crazy rationalisation of an audio queue into a circular buffer and decided just to trust the OS. This should reduce latency.
This commit is contained in:
Thomas Harte
parent
c284818af5
commit
de397799ed
@ -23,6 +23,6 @@
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@property (nonatomic, weak, nullable) id<CSAudioQueueDelegate> delegate;
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+ (Float64)preferredSamplingRate;
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@property (nonatomic, readonly) NSUInteger bufferSize;
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@property (nonatomic, readonly) NSUInteger preferredBufferSize;
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@end
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@ -10,77 +10,18 @@
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@import AudioToolbox;
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#define AudioQueueBufferMaxLength 8192
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#define AudioQueueNumAudioBuffers 3
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#define AudioQueueMaxStreamLength (AudioQueueBufferMaxLength*AudioQueueNumAudioBuffers)
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enum {
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AudioQueueCanProceed,
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AudioQueueWait,
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AudioQueueIsInvalidated
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};
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@implementation CSAudioQueue
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{
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NSUInteger _bufferLength;
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NSUInteger _streamLength;
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AudioQueueRef _audioQueue;
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AudioQueueBufferRef _audioBuffers[AudioQueueNumAudioBuffers];
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unsigned int _audioStreamReadPosition, _audioStreamWritePosition;
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int16_t _audioStream[AudioQueueMaxStreamLength];
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NSConditionLock *_writeLock;
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BOOL _isInvalidated;
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int _dequeuedCount;
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}
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#pragma mark -
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#pragma mark AudioQueue callbacks and setup; for pushing audio out
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#pragma mark - AudioQueue callbacks
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- (void)audioQueue:(AudioQueueRef)theAudioQueue didCallbackWithBuffer:(AudioQueueBufferRef)buffer
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{
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[self.delegate audioQueueDidCompleteBuffer:self];
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[_writeLock lock];
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const unsigned int writeLead = _audioStreamWritePosition - _audioStreamReadPosition;
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const size_t audioDataSampleSize = buffer->mAudioDataByteSize / sizeof(int16_t);
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// TODO: if write lead is too great, skip some audio
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if(writeLead >= audioDataSampleSize)
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{
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size_t samplesBeforeOverflow = _streamLength - (_audioStreamReadPosition % _streamLength);
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if(audioDataSampleSize <= samplesBeforeOverflow)
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{
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memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % _streamLength], buffer->mAudioDataByteSize);
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}
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else
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{
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const size_t bytesRemaining = samplesBeforeOverflow * sizeof(int16_t);
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memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % _streamLength], bytesRemaining);
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memcpy(buffer->mAudioData, &_audioStream[0], buffer->mAudioDataByteSize - bytesRemaining);
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}
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_audioStreamReadPosition += audioDataSampleSize;
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}
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else
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{
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memset(buffer->mAudioData, 0, buffer->mAudioDataByteSize);
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}
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if(!_isInvalidated)
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{
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[_writeLock unlockWithCondition:AudioQueueCanProceed];
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AudioQueueEnqueueBuffer(theAudioQueue, buffer, 0, NULL);
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}
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else
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{
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_dequeuedCount++;
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if(_dequeuedCount == AudioQueueNumAudioBuffers)
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[_writeLock unlockWithCondition:AudioQueueIsInvalidated];
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else
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[_writeLock unlockWithCondition:AudioQueueCanProceed];
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}
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AudioQueueFreeBuffer(_audioQueue, buffer);
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}
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static void audioOutputCallback(
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@ -91,19 +32,19 @@ static void audioOutputCallback(
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[(__bridge CSAudioQueue *)inUserData audioQueue:inAQ didCallbackWithBuffer:inBuffer];
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}
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#pragma mark - Standard object lifecycle
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- (instancetype)initWithSamplingRate:(Float64)samplingRate
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{
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self = [super init];
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if(self)
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{
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_writeLock = [[NSConditionLock alloc] initWithCondition:AudioQueueCanProceed];
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_samplingRate = samplingRate;
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// determine buffer sizes
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_bufferLength = AudioQueueBufferMaxLength;
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while((Float64)_bufferLength*50.0 > samplingRate) _bufferLength >>= 1;
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_streamLength = _bufferLength * AudioQueueNumAudioBuffers;
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// determine preferred buffer sizes
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_preferredBufferSize = AudioQueueBufferMaxLength;
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while((Float64)_preferredBufferSize*50.0 > samplingRate) _preferredBufferSize >>= 1;
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/*
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Describe a mono 16bit stream of the requested sampling rate
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@ -133,17 +74,6 @@ static void audioOutputCallback(
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0,
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&_audioQueue))
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{
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UInt32 bufferBytes = (UInt32)(_bufferLength * sizeof(int16_t));
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int c = AudioQueueNumAudioBuffers;
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while(c--)
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{
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AudioQueueAllocateBuffer(_audioQueue, bufferBytes, &_audioBuffers[c]);
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memset(_audioBuffers[c]->mAudioData, 0, bufferBytes);
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_audioBuffers[c]->mAudioDataByteSize = bufferBytes;
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AudioQueueEnqueueBuffer(_audioQueue, _audioBuffers[c], 0, NULL);
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}
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AudioQueueStart(_audioQueue, NULL);
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}
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}
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@ -158,51 +88,21 @@ static void audioOutputCallback(
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- (void)dealloc
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{
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[_writeLock lock];
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_isInvalidated = YES;
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[_writeLock unlock];
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[_writeLock lockWhenCondition:AudioQueueIsInvalidated];
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[_writeLock unlock];
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int c = AudioQueueNumAudioBuffers;
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while(c--)
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AudioQueueFreeBuffer(_audioQueue, _audioBuffers[c]);
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if(_audioQueue) AudioQueueDispose(_audioQueue, NO);
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}
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#pragma mark - Audio enqueuer
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- (void)enqueueAudioBuffer:(const int16_t *)buffer numberOfSamples:(size_t)lengthInSamples
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{
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if([_writeLock tryLockWhenCondition:AudioQueueCanProceed])
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{
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if((_audioStreamReadPosition + _streamLength) - _audioStreamWritePosition >= lengthInSamples)
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{
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size_t samplesBeforeOverflow = _streamLength - (_audioStreamWritePosition % _streamLength);
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AudioQueueBufferRef newBuffer;
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size_t bufferBytes = lengthInSamples * sizeof(int16_t);
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if(samplesBeforeOverflow < lengthInSamples)
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{
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memcpy(&_audioStream[_audioStreamWritePosition % _streamLength], buffer, samplesBeforeOverflow * sizeof(int16_t));
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memcpy(&_audioStream[0], &buffer[samplesBeforeOverflow], (lengthInSamples - samplesBeforeOverflow) * sizeof(int16_t));
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}
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else
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{
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memcpy(&_audioStream[_audioStreamWritePosition % _streamLength], buffer, lengthInSamples * sizeof(int16_t));
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}
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AudioQueueAllocateBuffer(_audioQueue, (UInt32)bufferBytes, &newBuffer);
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memcpy(newBuffer->mAudioData, buffer, bufferBytes);
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newBuffer->mAudioDataByteSize = (UInt32)bufferBytes;
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_audioStreamWritePosition += lengthInSamples;
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[_writeLock unlockWithCondition:[self writeLockCondition]];
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}
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else
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{
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[_writeLock unlockWithCondition:AudioQueueWait];
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}
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}
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}
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- (NSInteger)writeLockCondition
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{
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return ((_audioStreamWritePosition - _audioStreamReadPosition) < (_streamLength - _bufferLength)) ? AudioQueueCanProceed : AudioQueueWait;
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AudioQueueEnqueueBuffer(_audioQueue, newBuffer, 0, NULL);
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}
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#pragma mark - Sampling Rate getters
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@ -231,9 +131,4 @@ static void audioOutputCallback(
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return AudioObjectGetPropertyData([self defaultOutputDevice], &address, sizeof(AudioObjectPropertyAddress), NULL, &size, &samplingRate) ? 0.0 : samplingRate;
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}
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- (NSUInteger)bufferSize
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{
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return _bufferLength;
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}
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@end
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@ -85,7 +85,7 @@ class MachineDocument:
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audioQueue = CSAudioQueue(samplingRate: Float64(selectedSamplingRate))
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audioQueue.delegate = self
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self.machine.audioQueue = self.audioQueue
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self.machine.setAudioSamplingRate(selectedSamplingRate, bufferSize:audioQueue.bufferSize / 2)
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self.machine.setAudioSamplingRate(selectedSamplingRate, bufferSize:audioQueue.preferredBufferSize / 2)
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}
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self.bestEffortUpdater.clockRate = self.machine.clockRate
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