I was trying to pre-analyse FFT data to disk and play it back, to explore some time stretching approaches. I capture the two channels of FFT data post analysis to disk, then play them back with variable rate into an inverse FFT.

Problem is, the Window! It needs to happen in the time-domain just before the 2x overlap FFT and then windowed again at the iFFT stage. The iFFT is realtime, so how do I work with the window signal, which amplitude modulated the FFT data.

I tried already adjusting the rate of the iFFT window in realtime, by the same ratio as the disk based FFT data but this does not seem to work.

Any suggestions?