How to get array of float audio data from AudioQueueRef in iOS?

Question

I\'m working on getting audio into the iPhone in a form where I can pass it to a (C++) analysis algorithm. There are, of course, many options: the AudioQueue tutorial at tra

Answer 1

The above solution did not work for me, I was getting the wrong sample data itself.(an endian issue) If incase someone is getting wrong sample data in future, I hope this helps you :

-(void)feedSamplesToEngine:(UInt32)audioDataBytesCapacity audioData:(void *)audioData { int sampleCount = audioDataBytesCapacity / sizeof(SAMPLE_TYPE);

SAMPLE_TYPE *samples = (SAMPLE_TYPE*)audioData;
//SAMPLE_TYPE *sample_le = (SAMPLE_TYPE *)malloc(sizeof(SAMPLE_TYPE)*sampleCount );//for swapping endians

std::string shorts;
double power = pow(2,10);
for(int i = 0; i < sampleCount; i++)
{
    SAMPLE_TYPE sample_le =  (0xff00 & (samples[i] << 8)) | (0x00ff & (samples[i] >> 8)) ; //Endianess issue
    char dataInterim[30];
    sprintf(dataInterim,"%f ", sample_le/power); // normalize it.
    shorts.append(dataInterim);
}

Answer 2

  // so you don't have to hunt them all down when you decide to switch to float: 
  #define AUDIO_DATA_TYPE_FORMAT SInt16

  // the actual sample-grabbing code:
  int sampleCount = inBuffer->mAudioDataBytesCapacity / sizeof(AUDIO_DATA_TYPE_FORMAT);
  AUDIO_DATA_TYPE_FORMAT *samples = (AUDIO_DATA_TYPE_FORMAT*)inBuffer->mAudioData;

Then you have your (in this case SInt16) array samples which you can access from samples[0] to samples[sampleCount-1].