[FFmpeg-devel] [PATCH] Set generic yuv420 sampling in yuv4mpeg by default

Michael Niedermayer michaelni
Fri May 8 15:49:32 CEST 2009

On Thu, May 07, 2009 at 11:43:25PM -0400, David Conrad wrote:
> Hi,
> As discovered in #x264, the dump_psnr tool in Thusnelda actually cares 
> about chroma sample positions. This should probably be more correct; I 
> don't know for sure which codecs define which positioning.

many codecs leave it unspecified
h264 & mpeg4 match mpeg2 by default in theory, in how far the actual
data matches this of course is another question

h264 allows the exact chroma positions to be stored for 420
we could add a chroma_sample_location field to AVCodecContext maybe

anyway Thusneldas dump_psnr is broken if it does care about these values.
One cannot compare 2 raw images if chroma sample locations dont match
i guess theres no play that is too foul for xiphs propaganda machinery

the patch is fine but its not completly setting that field correctly

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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