iPhone Audio Queue sample rate question

I am in the process of making a piece of pitch correction software for the iPhone. I am currently at the fun Audio Queue part and I have a few questions about changing the pitch. My current idea to increase the pitch is to double the sampling rate and delete every other frame. I have it setup to record to a file and play from that file with LPCM forma开发者_C百科t. If I understand correctly lpcm has one frame per packet so deleting every other frame should be a piece of cake. What I am wondering before I try to tackle this part of the code is if I use lpcm, can I have the sampling rate different in different parts of the file? If not is there another format that would support having multiple sampling rates at different parts of the file?

You might want to experiment with the pitch shifting algorithm itself in a suitable environment first (e.g. MATLAB/Octave, or even just your preferred language on a desktop system). If it needs to work for music as well as speech then you probably want to look at implementing a phase vocoder.