[FFmpeg-devel] [PATCH] faster vp6 decoding

Sebastien Lucas sebastien.lucas
Tue Feb 10 15:40:14 CET 2009

On Tue, Feb 10, 2009 at 2:42 PM, Aurelien Jacobs <aurel at gnuage.org> wrote:
> Sebastien Lucas wrote:
>> On Tue, Feb 10, 2009 at 1:14 AM, Aurelien Jacobs <aurel at gnuage.org> wrote:
>> > I've slightly modified your patch (see attached):
>> >  - uses a vp6dsp_mmx.c file
>> >  - some cosmetics (no trailing whitespace, etc...)
>> >  - gcc 2.95 compat: you can't do for(int i=....)
>> >  - rough attempt at x86_64 compatibility
>> >
>> > Unfortunately it don't work (totally garbled output), but I've only
>> > tested it on x86_64.
>> I tested further, mplayer (latest svn vanilla build) don't manage to
>> decode properly my vp6 sample (it was working fine 1 month ago). So I
>> build ffmpeg, applied your modified patch and using -f framecrc (only
>> ssh access to my dev computer for now) I get 17 frames with changed
>> CRC out of the 2611 frames of my sample (I was previously testing only
>> the first 1000 frames with mplayer and there was no difference).
>> Logically there should be no difference at all.
>> But the "totally garbled output" you see could (~should~) be due to
>> x86_64. Can you point me the sample you used ?
> http://samples.mplayerhq.hu/FLV/flash8/harrypotter-480x272-450-vp6.flv
> (Any sample in the same directory should do too)

I just tested your sample with the following command line :
./ffmpeg -i ../../harrypotter-480x272-450-vp6.flv -an -f framecrc - >
with or without the patch and CRC always match.

So either my computer is blessed or the problem lies with X86_64. I'll
try to test it with another computer at home (no 64bits at home).

For the record I run an uptodate Debian Lenny with gcc version 4.3.2
(Debian 4.3.2-1.1).

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