Recording to AAC from RemoteIO: data is getting written but file unplayable

Question

I have been trying to record from a RemoteIO unit directly to AAC in a renderCallback in iOS 5 on an iPad 2. I have seen conflicting info saying it is not possible & tha

Answer 1

Did you write the magic cookie required at the start of an mpg 4 audio file?

You also need to do at least the first file write outside of the audio unit render callback.

Added:

Did you flush and close the audio file properly at the end? (outside of the AU callback)