[FFmpeg-devel] ac3 imdct question

Arpi arpi
Tue Oct 14 21:10:11 CEST 2008


> > I've tried to replace it (for experimenting with pitch correction...)
> > with the 'standard' inverse discrete fourier transform but it does
> > not work, the sound (ac3 music sample file) gets heavily distorted :(
> > here's my modification:
> I think your code is buggy ...
> see (fft_ref() in) fft-test.c

thanks, it was a big help!
i've found the bug in my code, i did not do the complex multiplication properly :(
(i assumed teh sin and cos values are 2 scalars, and not a single vector)

so decoding is now working fine, although my original idea (altering the
angle of sin/cos to change pitch) does not work...


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