[FFmpeg-devel] v210 decoder patch

[Michael Niedermayer]

Hi

On Wed, Jul 18, 2007 at 05:55:08PM -0400, Francois Oligny-Lemieux wrote:
> Hi,
> 
> I have questions/comments:
> 
> About the automatic generic function to extract YUV info. I began to draft
> it out yesterday and I found out it would work well on byte-aligned format.
> 
> However luma components in V210 are not byte-aligned. For example the first
> Y luma begins at bit 3. I think V210 wouldn't fit in this hypothetical
> generic yuv reader function.

then its useless, also ive already suggested a system which supports all
formats, see
http://article.gmane.org/gmane.comp.video.ffmpeg.devel/50389


> 
> Does anyone know other YUV formats that are not byte-aligned. I don't want
> to make it complicated just for one format.

RGB16 RGB15 are the most common examples
and
http://developer.apple.com/quicktime/icefloe/dispatch019.html
for a bunch of other cases


[...]
> >
> > > Do you mean adding swscale functions calls inside libavcodec/raw.c ?
> >
> > no
> > the only change needed in raw.c is likely adding a single line to
> > ff_raw_pixelFormatTags
> 
> 
> Then where would the sws function be called? Would it be in ffmpeg.c (around
> line 746) ? If yes, I think YUV formats should be converted right away in
> libavcodec to the closest (and non-degrading) swscale-supported YUV format
> and should not reach this stage in ffmpeg.c. Otherwise it will mean these
> redondant YUV formats will be spread around ffmpeg.

no a codec should not do colorspace convertion if it can be avoided
think of a display device which supports the specific format directly
forced convertion to 16bit and back is not good
the convert to 16bit is a hack, its not the way it should be done
ideally

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Good people do not need laws to tell them to act responsibly, while bad
people will find a way around the laws. -- Plato
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