how to modify the recorded audio data?

Hi, all

I'd like to add some music at the end of the recorded data. Do I need to add the music data before AudioQueueStop() or after? I tried to add it in the AudioQueueInputCallback()while the audio queue is running. It's not reliable. If add it after the audio queue is closed, are there any API with functionality of appending the additional data to the exist file.

Any sample or suggestion will be very appreciated, Thanks a lot!

 

Thanks!
But how to do with it?