[FFmpeg-devel] [PATCH] RoQ video encoder

Michael Niedermayer michaelni
Thu May 31 12:57:26 CEST 2007


On Wed, May 30, 2007 at 11:42:36PM -0400, Eric Lasota wrote:
> Hi,
> Michael Niedermayer wrote:
> > roq is a YV12 codec not a YUV 4:4:4 codec AFAIK so this is just wrong
> The actual RoQ decoder, the one used in Quake 3, uses RGB.  Check the
> cl_cin.c file.  Codebooks are converted out of 4:2:0 when they are
> loaded, and the 8x8 versions are also generated at that point.  This
> makes sense, as RoQ was created when 16-bit was popular, and and doing
> tons of copies was probably cheaper than doing colorspace conversion
> into 16-bit on a full frame on the hardware at the time.
> Chroma subsampling is merely done to reduce codebook size.  The
> authoritative RoQ decoder DOES NOT subsample chroma.  Using 4:4:4 is
> consequently the correct internal representation.  Ferguson's decoder,
> the one that FFMPEG was based off of, is incorrect.

hmm, iam CC-ing this to tim ferguson, lets see what his oppinion is about
it ...
if the framebuffers really are supposed to be in a non-croma-subsampled
format we should fix the decoder, this shouldnt be that bad as the thing
isnt that complex

on the encoder side i guess vitor wont be happy about it though ...
but then the codebook generation code is unaffected at least as that is
yv12 ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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