Looped Audio samples in the iPhone

Question

I am trying to made a musical iPhone application and I am having some problems playing looped samples.

I have read this question: audio-on-the-iphone

and several other posts and blogs in the web about the "RemoteIO"/AudioUnits framework but without success.

I have been able to do a sample application that plays a finite sound with a predefined duration (I am using a playbackCallback) but I need the sound to start playing with the user touches the screen and stop playing when the user lift the finger.

Any ideas?

Thanks in advance.

Answer 1

Assuming your code is correct, you're probably omitting one (or more) of these steps:

1. Stopping reading/writing at the wrong times (because you're likely writing 'a power of 2' samples per render call)
2. Not providing a fade in/fade out (start at 10 ms fade out and adjust as desired)
3. Not stopping write on a zero crossing
4. not resetting the read position to 0 when the user lifts their finger - resuming in the middle of the sample
5. Your samples are not properly trimmed to zero crossings at start, end, and/or loop positions
6. Not resetting internal effects, filters, or convertors

You will not need all of these to avoid clicks.