[MPlayer-dev-eng] Re: Vorbis decoding performance

[Balatoni Denes]

Hi!

Thanks for the benchmarks, looks good!
IMHO the reason why ffvorbis was so slow on the k6-III is the
non-SSE floating point mdct (k6-III has no SSE, right?).

Otherwise, ffvorbis was 20-30% faster than the floating-point official 
libvorbis when I was testing with ffmpeg a year ago (Uoti's benchmark shows 
something similar).

BTW if there was a fixed-point mdct in ffmpeg (xiph's can be stolen, but 
that's not too creative, is it) a blazing fast ffvorbis could be made, 
assuming that 32 bit is enough for mdct coefficients - the vorbis spec 
explicitly warns against this, and "mandates" 48 bits (and in fact tremor 
uses some tricky floating-point for this reason), but 32 bit is easily enough 
for all current vorbis streams/encoders.

bye
Denes

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