[FFmpeg-devel] dealing with tables in DV codec
Roman V. Shaposhnik
Thu Sep 11 04:27:13 CEST 2008
On Wed, 2008-09-10 at 23:06 +0200, Michael Niedermayer wrote:
> On Wed, Sep 10, 2008 at 12:46:22PM -0700, Roman Shaposhnik wrote:
> > On Wed, 2008-09-10 at 21:37 +0200, Michael Niedermayer wrote:
> > > > Thanks for saying this. On one hand Michael uses embedded systems
> > > > as a constant argument in favor of optimizing for such
> > > > platforms, but on the other hand there's a clear x86 tilt
> > > > that I see.
> > >
> > > /me cleans romans glasses.
> > >
> > > I suggest you ask balatoni denes about how easy it was to get a half optimal
> > > sparc vis idct into ffmpeg.
> > I'm actually unaware of what you are referring to. Please educate me.
> balatoni denes tried to get a half optimized idct in and i nicely told
> him that it has to include all tricks and optimizations we could think of.
> We ended up with something that was clearly quite a bit faster than
> what he submitted first, that is between all the complaints about how
> little time he had and how evil we were for not just acceptiing it as
Seems like you've confused the threads, then. I fail to see the
relevance of this war story to the issue at hand -- should the
change that is a toss up on x86 and ~3% performance degradation
on SPARC be included or not.
> That besides reminds me that rumors say the mlib idct is so inaccurate
> that its practically useless.
> As iam not able to test, i wonder how bad it really is ...
It is actually pretty decent. At least the portions I used to
make the DV codec go. Once again -- I'm talking exclusively
about SPARC. I have no interest in mlib on x86.
> on samples.mplayerhq.hu is a good one to test idcts.
Do you mean just comparing PSNRs or a more involved test?
> > So one of the things I'm trying to do is to see whether the code
> > that is really needed for FFmpeg (medialib is huge, we only need
> > like 2% of it) could be OSed under a reasonable license that would
> > allow direct inclusion into FFmpeg sources.
> > Should I stop it?
> stupid question,
repeat after me: there are no stupid questions, there are no stupid
> Though honestly my gut feeling is that anyone knowing VIS and sparc asm
Do you have anyone like that on the horizon?
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