[FFmpeg-devel] A further potential optimization of H264 deblocking

Guy Bonneau gbonneau
Tue May 29 20:49:44 CEST 2007

Thanks Jindrich,

I suspect that this is because of the carry over to the 9th bit
of expression q0+~p0 + 1 which can be done only inside a pavgb.
Thus no further optimization.

Guy Bonneau.

>-----Original Message-----
>From: ffmpeg-devel-bounces at mplayerhq.hu [mailto:ffmpeg-devel-
>bounces at mplayerhq.hu] On Behalf Of Jindrich Makovicka
>Sent: Tuesday, May 29, 2007 2:22 PM
>To: ffmpeg-devel at mplayerhq.hu
>Subject: Re: [FFmpeg-devel] A further potential optimization of H264
>On Tue, 29 May 2007 13:58:08 -0400
>"Guy Bonneau" <gbonneau at matrox.com> wrote:
>> While I was studying the deblocking algorithm of the H264
>> specification I dug in the ffmpeg mmx implementation to understand
>> how this is implemented. I had a hard time to understand the
>> optimization so I went through the Binary Math. Yet while doing the
>> Math I think I might have found a small further optimization.
>> Its is a 3 instructions gain over 20 instructions.
>> Unfortunately I cannot try it myself since I'm using Windows
>> and this is theoretical stuff. If someone can do it I would
>> be interested to know if it works or I missed something.
>I just tried mplayer -vo md5sum and the results are different from the
>original code.
>Jindrich Makovicka
>ffmpeg-devel mailing list
>ffmpeg-devel at mplayerhq.hu

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