[Theora-dev] Re: MMX/mmxext optimisations

Ralph Giles giles at xiph.org
Wed Aug 25 14:07:12 PDT 2004

On Wed, Aug 25, 2004 at 10:10:22PM +0100, Jim Darby wrote:

> > One down size is that to my eye, mmx-encoded theora videos are
> > slightly blurrier than their standard counterparts, for a fixed
> > target bitrate.  Also, for a fixed quality factor, the files seem
> > quite a lot smaller (but not particularly worse-looking on brief
> > inspection, which is odd and counter-intuitive given the first
> > observation, but I'm not complaining).
> This is a little worrying. Surely the MMX code should just make things
> happen faster rather than different?

Indeed. Of course it's easy to fool yourself, but particularly because 
errors are cumulative between I frames, the in-loop stuff does need
to be per spec.

Wim, can you confirm you didn't include any short cuts?


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