How to convert from Inverse Fast Fourier Transform to .wav?

I used made a fft to make a band pass filter. After that I made the ifft to inverse it and pass it to time domain.

My ifft has the same length of the fft.

The ifft must be longer or开发者_如何学Python is there a way to make it longer? How do I pass this ifft to .wav?

The WAV file format is documented pretty well (see below). It's basically some header information followed by the raw sample data.

first result with Google: https://ccrma.stanford.edu/courses/422/projects/WaveFormat/