Playing two simultaneous m4a sounds with audioqueue

I need to mix two simultaneous looping m4a sounds for my application, and the on开发者_Python百科ly 100% reliable loop method i have come accross is using AudioQueue with this method: http://developer.apple.com/mac/library/qa/qa2009/qa1636.html

However, when I initialize two instances of AudioQueue, I can only seem to get one instance playing. I know that the sdk used to only support playing one compressed audio file at a time, but that changed with 3.0, so I wonder if there is something I am missing?

One current devices, there seems to be hardware support for only playing one compressed audio file at a time, and I'm not sure if m4a is de-compressible in software in real-time (there are only specific types supported by the software decoder). You might be able to decompress the second sound before playing your mixed audio loops.