[FFmpeg-devel] [PATCH] split-radix FFT

Måns Rullgård mans
Sun Aug 3 22:25:11 CEST 2008

Loren Merritt <lorenm at u.washington.edu> writes:

> $subject, vaguely based on djbfft.
> Changed from djb:
> * added simd.
> * removed the hand-scheduled pentium-pro code. gcc's output from
> simple C is better on all cpus I have access to.
> * removed the distinction between fft and ifft. they're just
> permutations of eachother, so the difference belongs in revtab[] and
> not in the code.
> * removed the distinction between pass() and pass_big(). C can always
> use the memory-efficient version, and simd never does because the
> shuffles are too costly.
> * made an entirely different pass_big(), to avoid store->load aliasing.

Any progress on this?  IMDCT is taking 84% time decoding Vorbis on
ARM, and SIMD-optimising the FFT in svn seems silly.

M?ns Rullg?rd
mans at mansr.com

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