[MPlayer-users] Re: divx 6

[Rich Felker]

On Fri, Apr 28, 2006 at 11:57:13AM -0700, Loren Merritt wrote:
> On Fri, 28 Apr 2006, Rich Felker wrote:
> >gmc is intentionally not supported because it's an idiotic feature. It
> >makes streams that are MUCH slower to decode and does not improve
> >quality measurably.
> 
> MUCH = 5%? because that's how much gmc costs after I mmx'ed it.
> That said, I agree on gmc not doing much of anything, so 5% is way too 
> expensive for a nop.

Cache thrashing is not any fixed percentage. Full GMC means you have
to use an extra buffer, unless you have some crazy optimization to
avoid that. And that can have all kinds of cache impacts which depend
on resolution, audio codec, other processes running, filters in use,
etc. etc. etc.

> >WTF does "supporting cartoon mode" mean? I don't see "cartoon mode"
> >mentioned in the ISO MPEG-4 spec anywhere. If you mean "does it have
> >analogous optimizations" then someone familiar with xvid needs to
> >explain wtf "cartoon mode" does so we can answer.
> 
> bias towards mv=(0,0).
> increases vlelim and vcelim.
> so lavc has half of it.

*nod*
Thanks for an intelligent explanation. And thanks to xvid for treating
their users like idiots rather than correctly calling the option "mv
bias weight" or something and making it fully tunable.

Rich