Specifying number of samples for a custom xaudio2 effect

Question

I'm trying to write a custom xaudio2 effect that involves a fourier transform. However, the number of samples given to the process method each call is not a power of 2 (a precondition of the fourier transform implementation I have).

Is there a way to force power of 2 sized samples? Is there a technique to allow working with non power of 2 sizes?

Answer 1

Don't send samples to the FFT every call that you are given samples. Buffer (save) them up till you have at least a power-of-2 samples or more and then process the power-of-2 number of samples from your intermediate buffer. Rinse and repeat.

Also, newer FFTs will often allow sizes with prime factors larger than 2.

Answer 2

If your implementation requires that you have a power of 2 sample size, then you can pad the sample to force it to accept. Zero padding seems to be the easiest/most straight forward.

Here is an article that explains another way to do it:

The Chirp z-Transform Algorithm and Its Application