Slightly more correct demo behaviour

test/demo_oswrapper_audio_mac.c

@@ -53,21 +53,48 @@ static int audio_done = 0;
 
 static OSStatus Callback(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData) {
  int amount_done;
+ UInt32 out_size;
  OSWrapper_audio_spec* audio_spec = (OSWrapper_audio_spec*)inRefCon;
  (void)ioActionFlags;
  (void)inTimeStamp;
  (void)inBusNumber;
 
+ // This will probably never happen
+ if (!ioData || (ioData->mNumberBuffers != 1)) {
+ return -50;
+ }
+
+ out_size = ioData->mBuffers[0].mDataByteSize;
+
+ // This will probably never happen
+ if (out_size == 0) {
+ *ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
+ return 0;
+ }
+
  if (audio_spec == NULL) {
+ memset(ioData->mBuffers[0].mData, 0, out_size);
+ ioData->mBuffers[0].mDataByteSize = 0;
+ *ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
  return 0;
  }
 
  /* Because the stream is interleaved, there is only one buffer */
  amount_done = oswrapper_audio_get_samples(audio_spec, (short*)ioData->mBuffers[0].mData, inNumberFrames);
 
  if (amount_done == 0) {
+ memset(ioData->mBuffers[0].mData, 0, out_size);
+ ioData->mBuffers[0].mDataByteSize = 0;
+ *ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
  audio_done = 1;
  pthread_cond_signal(&pthread_condition);
+ } else {
+ UInt32 mult_done = (amount_done * ((audio_spec->bits_per_channel / 8) * (audio_spec->channel_count)));
+
+ if (out_size > mult_done) {
+ memset((unsigned char*)ioData->mBuffers[0].mData + mult_done, 0, out_size - mult_done);
+ ioData->mBuffers[0].mDataByteSize = mult_done;
+ }
  }
 
  return 0;