AVAssetReader to AudioQueueBuffer

Question

Currently, I\'m doing a little test project to see if I can get samples from an AVAssetReader to play back using an AudioQueue on iOS.

I\'ve read this: ( Play raw un

Answer 1

For some reason, even though every example I've seen of the audio queue using LPCM had

ASBD.mBitsPerChannel = 8* sizeof (AudioUnitSampleType);

For me it turns out I needed

ASBD.mBitsPerChannel    = 2*bytesPerSample;

for a description of:

ASBD.mFormatID          = kAudioFormatLinearPCM;
ASBD.mFormatFlags       = kAudioFormatFlagsAudioUnitCanonical;
ASBD.mBytesPerPacket    = bytesPerSample;
ASBD.mBytesPerFrame     = bytesPerSample;
ASBD.mFramesPerPacket   = 1;
ASBD.mBitsPerChannel    = 2*bytesPerSample;
ASBD.mChannelsPerFrame  = 2;           
ASBD.mSampleRate        = 48000;

I have no idea why this works, which bothers me a great deal... but hopefully I can figure it all out eventually.

If anyone can explain to me why this works, I'd be very thankful.