[FFmpeg-soc] Differing

Michael Niedermayer michaelni at gmx.at
Wed Jul 22 09:48:33 CEST 2009


On Wed, Jul 22, 2009 at 01:58:16AM -0300, Ramiro Polla wrote:
> Hi,
> 
> In swscale.c, there are some lines that adjust {lum,chr}XInc depending
> on MMX or MMX2 being used for fast bilinear. They were added (still
> with the old name of s_xinc) in this commit:
> http://git.ffmpeg.org/?p=libswscale;a=commitdiff;h=87d2542e33c80731dab64339aebcaebbaa25911e
> 
> Where do the magical "20" values come from?

i dont remember ATM


> 
> >From what I understood and from some tests I've done, this creates
> some rather ugly last lines at the far right of the image. The output
> also differs for C, mmx, and mmx2, and it's not under BITEXACT.
> 
> To remove this adjustment and have the same output for all
> configurations, wouldn't it only be necessary to:
> - adjust mmx and mmx2 filters to only work up to the last input pixels
> it can before reading past the end.
> - run the C code on the last pixels if necessary.

that would need a benchmark, after all the fast_bilinear case is intended
to be fast ...

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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