Mixing sound files on an iPhone

Question

I've got a couple of wav files and possibly a mp3 that I'd like to mix down to a single wav or mp3-file. I'm using C/C++/Obj-C (iPhone). I have really no experience with this sort of thing. If anyone could give me some pointers, I would be very grateful.

Basically what I want to do is similar things like for example Audacity can do, but programmatically. Isn't there a sound library where you can easily open audio files and "paste" them into a new one at defined positions? Where mixing is something you don't have to worry about?

Thanks.

Answer 1

Mixing two sound buffers of linear PCM is only a matter of adding each sample value in them together, and of course make sure you don't overflow. Normally you would use floating point values in the buffers though, so the issue is when you go back to the file. You should also have CoreAudio available on the iPhone, it has all the means to open/read/write sound files in different formats. I think there is also a more high level api available to the iPhone that isn't on the mac, look up the apple docs.

Answer 2

If you are specifically looking for the features of Audacity, it uses PortAudio under the hood (looks like an MIT license). Perhaps you can just try to use that?