[FFmpeg-devel] [PATCH] Optimisations for av_log2 and integer clip functions

Måns Rullgård mans
Thu Jan 14 04:51:30 CET 2010

Yuriy Kaminskiy <yumkam at mail.ru> writes:

> On 14.01.2010 03:31, M?ns Rullg?rd wrote:
>> Michael Niedermayer <michaelni at gmx.at> writes:
>>> On Wed, Jan 13, 2010 at 05:55:26PM -0500, Jason Garrett-Glaser wrote:
> [...]
>>> If thats to easy one also could factor the question in about the speed
>>> difference actually making a difference for a file a user wants to play
>> Perhaps someone with an AMD processor could try the patch on a flac file.
> amd k8 - x2 4850e, 32bit, gcc-4.1.2, -march=pentium3 -mtune=k8
> ffmpeg-mt-20100104,
> mplayer -nocache -ao pcm:fast:nowaveheader:file=/dev/null *.flac
> before: user	0m7.140s (best of few runs)
> after:  user	0m8.085s

Well, that's bad...

I tested it on PPC (g4), and the clz version is consistently 4% faster

I suppose we need to make a list of good and bad CPUs.

M?ns Rullg?rd
mans at mansr.com

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