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As an initial step, ensured latency doesn't pile up endlessly.

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This commit is contained in:
Thomas Harte 2018-05-15 21:12:43 -04:00
parent 7c2721d54d
commit f7decd80b6
1 changed files with 18 additions and 20 deletions
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36
OSBindings/Mac/Clock Signal/Audio/CSAudioQueue.m
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@ -27,9 +27,9 @@ static NSLock *CSAudioQueueDeallocLock;
@implementation CSAudioQueue { @implementation CSAudioQueue {
AudioQueueRef _audioQueue; AudioQueueRef _audioQueue;
AudioQueueBufferRef _storedBuffers[NumberOfStoredAudioQueueBuffer];
NSLock *_storedBuffersLock; NSLock *_storedBuffersLock;
CSWeakAudioQueuePointer *_weakPointer; CSWeakAudioQueuePointer *_weakPointer;
int _enqueuedBuffers;
} }
#pragma mark - AudioQueue callbacks #pragma mark - AudioQueue callbacks
@ -39,16 +39,19 @@ static NSLock *CSAudioQueueDeallocLock;
*/ */
- (BOOL)audioQueue:(AudioQueueRef)theAudioQueue didCallbackWithBuffer:(AudioQueueBufferRef)buffer { - (BOOL)audioQueue:(AudioQueueRef)theAudioQueue didCallbackWithBuffer:(AudioQueueBufferRef)buffer {
[_storedBuffersLock lock]; [_storedBuffersLock lock];
for(int c = 0; c < NumberOfStoredAudioQueueBuffer; c++) { --_enqueuedBuffers;
if(!_storedBuffers[c] || buffer->mAudioDataBytesCapacity > _storedBuffers[c]->mAudioDataBytesCapacity) {
if(_storedBuffers[c]) AudioQueueFreeBuffer(_audioQueue, _storedBuffers[c]); // If that leaves nothing in the queue, re-enqueue whatever just came back in order to keep the
_storedBuffers[c] = buffer; // queue going. AudioQueues seem to stop playing and never restart no matter how much encouragement
[_storedBuffersLock unlock]; // if exhausted.
return YES; if(!_enqueuedBuffers) {
} AudioQueueEnqueueBuffer(theAudioQueue, buffer, 0, NULL);
} ++_enqueuedBuffers;
[_storedBuffersLock unlock]; } else {
AudioQueueFreeBuffer(_audioQueue, buffer); AudioQueueFreeBuffer(_audioQueue, buffer);
}
[_storedBuffersLock unlock];
return YES; return YES;
} }
@ -158,18 +161,12 @@ static void audioOutputCallback(
size_t bufferBytes = lengthInSamples * sizeof(int16_t); size_t bufferBytes = lengthInSamples * sizeof(int16_t);
[_storedBuffersLock lock]; [_storedBuffersLock lock];
for(int c = 0; c < NumberOfStoredAudioQueueBuffer; c++) { // Don't enqueue more than 4 buffers ahead of now, to ensure not too much latency accrues.
if(_storedBuffers[c] && _storedBuffers[c]->mAudioDataBytesCapacity >= bufferBytes) { if(_enqueuedBuffers > 4) {
memcpy(_storedBuffers[c]->mAudioData, buffer, bufferBytes);
_storedBuffers[c]->mAudioDataByteSize = (UInt32)bufferBytes;
AudioQueueEnqueueBuffer(_audioQueue, _storedBuffers[c], 0, NULL);
_storedBuffers[c] = NULL;
[_storedBuffersLock unlock]; [_storedBuffersLock unlock];
return; return;
} }
} ++_enqueuedBuffers;
[_storedBuffersLock unlock];
AudioQueueBufferRef newBuffer; AudioQueueBufferRef newBuffer;
AudioQueueAllocateBuffer(_audioQueue, (UInt32)bufferBytes * 2, &newBuffer); AudioQueueAllocateBuffer(_audioQueue, (UInt32)bufferBytes * 2, &newBuffer);
@ -177,6 +174,7 @@ static void audioOutputCallback(
newBuffer->mAudioDataByteSize = (UInt32)bufferBytes; newBuffer->mAudioDataByteSize = (UInt32)bufferBytes;
AudioQueueEnqueueBuffer(_audioQueue, newBuffer, 0, NULL); AudioQueueEnqueueBuffer(_audioQueue, newBuffer, 0, NULL);
[_storedBuffersLock unlock];
} }
#pragma mark - Sampling Rate getters #pragma mark - Sampling Rate getters