[FFmpeg-devel] need help fixing sws on PPC

Vitor Sessak vitor1001
Mon Oct 6 21:42:56 CEST 2008

Michael Niedermayer escreveu:
> On Wed, Sep 10, 2008 at 01:42:44PM +0200, Vitor Sessak wrote:
>> Michael Niedermayer escreveu:
>>> Hi
>>> Can someone who has a PPC and a x86 play a little with swscale to find
>>> out which convertions do not match?
>>> This is rather important as our regression tests as well as fate depend
>>> on it.
>>> Note -sws_flags +bitexact should be used also -sws_flags +accurate_rnd
>>> may be needed.
>>> Also note, some scalers still use floats to find coeffs (like spline)
>>> iam not interrested in them, that is currently area, nearest neighbor
>>> bilinear and bicubic are the onlx ones iam interrested in.
>>> And last, if something does not match, pleas explain how it does differ
>>> +-1 rounding or red/blue exchanged or ...
>> Besides rounding, there is still something wierd about swscale. For 
>> example, I was looking at he idcin test 
>> http://fate.multimedia.cx/index.php?test_spec=107 .
> [...]
>> Unless I am missing something, there should be no calculation (and even 
>> less rounding) doing PAL8 -> RGB conversion, but it still gives 
>> different output with and without swscaler.


> if you only care about the unscaled pal->rgb24/32 case, you can add a special
> converter for that case, which should be trivial.

Here is my try at it. I really think it is important to be able to test 
palette-based decoders without doing a full regression test of all asm 
versions of rgb2yuv/yuv2rgb...

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