[MPlayer-dev-eng] Re: Vorbis decoding performance
Diego Biurrun
diego at biurrun.de
Wed Aug 2 21:47:34 CEST 2006
On Wed, Aug 02, 2006 at 10:38:39PM +0200, Balatoni Denes wrote:
>
> 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?).
Yes, K6-III has 3dnow and 3dnowext and mmx, but no sse.
> 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.
Any volunteers? Outperforming Xiph's decoder in all situations would be
way cool :-)
Diego
More information about the MPlayer-dev-eng
mailing list