[Ffmpeg-devel] [PATCH] Snow mc_block mmx optimization

Oded Shimon ods15
Sun Mar 26 22:24:05 CEST 2006

On Sun, Mar 26, 2006 at 09:48:41PM +0200, Michael Niedermayer wrote:
> On Sun, Mar 26, 2006 at 03:10:17PM +0200, Oded Shimon wrote:
> > Ping.
> pong

pin... missed! lost the ball.. damnit, I lose...

> after more carefull review of this iam not so sure anymore if its a good idea
> * doesnt this change 1/2 pel (no qpel) encoding?

I don't see how, mc_block has the exact same behavior. From what I could 
figure from RTFS, dx and dy are always 0<=d<=15, and always even. I just 
tested out another odd resolution video (364x241), md5sum still match.

BTW, widths that divide by 4 now do work for me, but anything less still 
mencoder: snow.c:2438: pred_block: Assertion `b_w>1 && b_h>1' failed.
I'm not sure why only widths that divide by 8 worked for me earlier, maybe 
I was using out of date cvs. This is up to date to yesterday night though.

BTW2, can 'assert(!(b_w&3))' ever fail in mc_block ? If not, I can remove 
the C code duplication in the mmx functions... I know b_h was still 
divisable by 8 in this odd res video. Can't know about b_w cause encoding 
doesn't work...

> * currently we have 2 different MC variants, 1. the h.264 case for 1/4 pel
>   and our own for 1/8 pel, i really disslike this, we should attempt to
>   find a more unified method

I'm generally clueless about this, either way, my MMX still stands and I 
would like it committed as it's the last piece missing for me to play a 
944x544 snow file smoothly... Even the C code is significantly faster...

- ods15

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