[FFmpeg-devel] [PATCH] MMX VP3 Loop Filter

[David Conrad]

On Oct 7, 2008, at 5:43 AM, Jason Garrett-Glaser wrote:

>> Here's an 8-bit version. However, checking for the C fallback  
>> negates the
>> small speedup on my Penryn compared to the 16-bit version.
>
> Most of the code is still 16-bit.  Are you sure this can't be done
> x264-style with emulation of extra bits and 8-bit math (reference for
> an example of how to do this: common/x86/deblock-a.asm in x264 tree)?
> This would eliminate the need for all unpacks, all packs, and all
> multiplication, and probably increase speed dramatically.  I strongly
> suspect that it can be done, as the deblocking formulas seem very
> similar to those used in H.264.

It seems like you're right; the only difference between DEBLOCK_P0_Q0  
and VP3 is a *3 vs. a *4 in H.264.
I don't quite fully understand x264's implementation, so it'll take  
another bit to adapt it.