objective c - How to set pitch of an audio file or recorded audio file in iphone sdk?

Question

I am recoding a file or I have audio file I want to change the pitch and play the audio file. How can I set the pitch in a iphone program that is using objective-c.

Please help me out of this.

Thank you, Madan Mohan.

Answer 1

The naive approach is to play it using a different sampling rate as compared to the sampling rate used to record the file. For example, if the file was recorded with Fs=44100Hz, then playing it with Fs=22050Hz, will give you half the original pitch.

Of course this naive approach involves changing the duration of the file, and other sound-related artifacts. If you need something less naive, you will have to implement a pitch-shifting algorithm yourself, and that's a huge topic --- I suggest you start by searching pitch shift in google.