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Switched to being explicitly careful about not wrapping around and stomping on data not yet output.

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This commit is contained in:
Thomas Harte 2016-01-18 13:56:20 -06:00
parent ddcc34740b
commit b70fdc2de8
1 changed files with 45 additions and 34 deletions
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79
OSBindings/Mac/Clock Signal/Wrappers/AudioQueue.m
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@ -13,12 +13,18 @@
#define AudioQueueStreamLength 2048
#define AudioQueueBufferLength 512
enum {
AudioQueueCanWrite,
AudioQueueWait
};
@implementation AudioQueue
{
AudioQueueRef _audioQueue;
AudioQueueBufferRef _audioBuffers[AudioQueueNumAudioBuffers];
unsigned int _audioStreamReadPosition, _audioStreamWritePosition;
int16_t _audioStream[AudioQueueStreamLength];
NSConditionLock *_writeLock;
}
@ -27,31 +33,32 @@
- (void)audioQueue:(AudioQueueRef)theAudioQueue didCallbackWithBuffer:(AudioQueueBufferRef)buffer
{
@synchronized(self)
[_writeLock lock];
const unsigned int writeLead = _audioStreamWritePosition - _audioStreamReadPosition;
const size_t audioDataSampleSize = buffer->mAudioDataByteSize / sizeof(int16_t);
if(writeLead >= audioDataSampleSize*2)
{
const unsigned int writeLead = _audioStreamWritePosition - _audioStreamReadPosition;
const size_t audioDataSampleSize = buffer->mAudioDataByteSize / sizeof(int16_t);
if(writeLead >= audioDataSampleSize)
size_t samplesBeforeOverflow = AudioQueueStreamLength - (_audioStreamReadPosition % AudioQueueStreamLength);
if(audioDataSampleSize <= samplesBeforeOverflow)
{
size_t samplesBeforeOverflow = AudioQueueStreamLength - (_audioStreamReadPosition % AudioQueueStreamLength);
if(audioDataSampleSize <= samplesBeforeOverflow)
{
memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % AudioQueueStreamLength], buffer->mAudioDataByteSize);
}
else
{
const size_t bytesRemaining = samplesBeforeOverflow * sizeof(int16_t);
memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % AudioQueueStreamLength], bytesRemaining);
memcpy(buffer->mAudioData, &_audioStream[0], buffer->mAudioDataByteSize - bytesRemaining);
}
_audioStreamReadPosition += audioDataSampleSize;
memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % AudioQueueStreamLength], buffer->mAudioDataByteSize);
}
else
{
memset(buffer->mAudioData, 0, buffer->mAudioDataByteSize);
const size_t bytesRemaining = samplesBeforeOverflow * sizeof(int16_t);
memcpy(buffer->mAudioData, &_audioStream[_audioStreamReadPosition % AudioQueueStreamLength], bytesRemaining);
memcpy(buffer->mAudioData, &_audioStream[0], buffer->mAudioDataByteSize - bytesRemaining);
}
AudioQueueEnqueueBuffer(theAudioQueue, buffer, 0, NULL);
_audioStreamReadPosition += audioDataSampleSize;
}
else
{
memset(buffer->mAudioData, 0, buffer->mAudioDataByteSize);
}
AudioQueueEnqueueBuffer(theAudioQueue, buffer, 0, NULL);
[_writeLock unlockWithCondition:AudioQueueCanWrite];
}
static void audioOutputCallback(
@ -68,10 +75,10 @@ static void audioOutputCallback(
if(self)
{
_writeLock = [[NSConditionLock alloc] initWithCondition:AudioQueueCanWrite];
/*
Describe a mono, 16bit, 44.1Khz audio format
*/
AudioStreamBasicDescription outputDescription;
@ -123,22 +130,26 @@ static void audioOutputCallback(
- (void)enqueueAudioBuffer:(const int16_t *)buffer numberOfSamples:(size_t)lengthInSamples
{
@synchronized(self)
[_writeLock lockWhenCondition:AudioQueueCanWrite];
size_t samplesBeforeOverflow = AudioQueueStreamLength - (_audioStreamWritePosition % AudioQueueStreamLength);
if(samplesBeforeOverflow < lengthInSamples)
{
size_t samplesBeforeOverflow = AudioQueueStreamLength - (_audioStreamWritePosition % AudioQueueStreamLength);
if(samplesBeforeOverflow < lengthInSamples)
{
memcpy(&_audioStream[_audioStreamWritePosition % AudioQueueStreamLength], buffer, samplesBeforeOverflow * sizeof(int16_t));
memcpy(&_audioStream[0], &buffer[samplesBeforeOverflow], (lengthInSamples - samplesBeforeOverflow) * sizeof(int16_t));
}
else
{
memcpy(&_audioStream[_audioStreamWritePosition % AudioQueueStreamLength], buffer, lengthInSamples * sizeof(int16_t));
}
_audioStreamWritePosition += lengthInSamples;
memcpy(&_audioStream[_audioStreamWritePosition % AudioQueueStreamLength], buffer, samplesBeforeOverflow * sizeof(int16_t));
memcpy(&_audioStream[0], &buffer[samplesBeforeOverflow], (lengthInSamples - samplesBeforeOverflow) * sizeof(int16_t));
}
else
{
memcpy(&_audioStream[_audioStreamWritePosition % AudioQueueStreamLength], buffer, lengthInSamples * sizeof(int16_t));
}
_audioStreamWritePosition += lengthInSamples;
[_writeLock unlockWithCondition:[self writeLockCondition]];
}
- (NSInteger)writeLockCondition
{
return ((_audioStreamWritePosition - _audioStreamReadPosition) < AudioQueueStreamLength) ? AudioQueueCanWrite : AudioQueueWait;
}
@end