[FFmpeg-devel] [PATCH] modification of the MMX H264 MC chroma functions to support RV40

Michael Niedermayer michaelni
Thu Dec 25 20:00:57 CET 2008

On Thu, Dec 25, 2008 at 06:03:32PM +0100, Mathieu Velten wrote:
> 2008/12/23 Mathieu Velten <matmaul at gmail.com>:
> > 2008/12/23 Michael Niedermayer <michaelni at gmx.at>:
> >>> or use a bigger rv40_bias table and use a shift to find the >>3
> >>> variant in the table ?
> >>
> >> yes
> >>
> >
> > I still don't know how to do.
> > I don't want to use the rv40 table inside dsputil_h264_template_mmx.c
> > if possible to do not pollute h264 code with a rv40 table.
> >
> > I can use a bigger table before the call of the function and I pass
> > rng_reg and rng_reg_div_8 as arguments, but I am not sure it will be
> > faster.
> I don't think a single instruction which is only for the 1 dimensional
> case and which is only execute once per function call (not in the for)
> is a big deal, and it will be a mess if I try to use a table.

{a,a>>3,b,b>>3, ...
doesnt look like a big mess to me

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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