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

matthieu castet castet.matthieu
Mon Aug 4 21:27:36 CEST 2008

M?ns Rullg?rd wrote:
> 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.
Shouldn't fixed point stuff should help a lot on arm ?

IRRC there was post about wma and cook fixed point implementation that 
were lot's of faster on such cpu.


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