[CELT-dev] Modifications of kiss_fft/compatibility with original kiss_fft code?

Timothy B. Terriberry tterribe at xiph.org
Sun Feb 20 15:30:18 PST 2011

> code, I would like to check whether the changes, that were made to the
> original kiss_fft code, change the actual behaviour of the kiss_fft
> function or whether they were only made for speed improvement or
> cosmetic reasons. In other words, could I still replace the functions
> "kiss_fft_alloc" and "kiss_fft" with the original code (apart from the
> fact that there are now functions for the inverse transformation in celt)?

They were made mostly for data organization reasons (i.e., to allow 
static data and sharing of twiddles between FFTs of different sizes). 
The actual transforms should be the same. I'd need to double-check for 
fixed-point, but in my decoder re-implementation, I was able to start 
from the current kisfft release and achieve compatibility with the float 
code without changing the actual calculations involved.

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