[FFmpeg-devel] [PATCH] Add colorspace properties to pixdesc

[Michael Niedermayer]

On Fri, May 01, 2009 at 11:31:38PM +0200, Stefano Sabatini wrote:
> On date Thursday 2009-04-30 03:34:13 +0200, Michael Niedermayer encoded:
> > On Thu, Apr 30, 2009 at 01:49:20AM +0200, Stefano Sabatini wrote:
> > > Hi,
> > > 
> > > this seems required for colorutils.c, just a preliminary patch though.
> > > 
> > > In order to convert a color from one pixfmt to another one I need to
> > > know the colorspace, then I should be able to apply the correct macro
> > > from libavcodec/colorspace.h.
> > > 
> > > Then I'll need to eventually scale each component value, and finally
> > > assign it to the correct component (for this I need the AVComponent
> > > color).
> > > 
> > > I'm not sure this is the rigth approach, so before to fill the
> > > pixdesc.c table I'd like to hear your opinion.
> > 
> > ideg
> > this patch wins the most broken patch award of the year
> > 
> > let me explain (it should be obvious but it seems not)
> > 
> > One of the key goals of the pixfmt structure was 
> > _TO_SEPERATE_THE_COLORSPACE_FROM_HOW_THE_BITS_OF_THE_PIXELS_ARE_STORED_
> > 
> > Why would we want that?
> > again should be obvious but is obviously not :(
> > These are 2 semmantically seperate things, we will not duplicate the list
> > of all yuv formats 12 times because there are 6 yuv types and 2 (jpeg vs mpeg)
> > style ranges.
> 
> So I wonder what's the point of the PIX_FMT_YUVJ* pixfmts? 
> Should they
> be removed?

a quick hack to solve the problem to 95% with minimal work, it was fabrices
idea, they served us well but yes they should be removed once a more
powerfull system is available


> 
> > So repeating the forgotten discussions ...
> > a colorspace enum should be added to AVCodecContext
> 
> So we could end up with this:
> pixfmt/pixdesc define the disposition, depth, etc. of each component,
> but gives no hint for what regards the current color and colorspace of
> each component.
> 
> So we could have for example a PIX_FMT_YUV420, and the colorspace
> could by YUV, YUV_JPEG, YUV_MJPEG, the colorspace info being stored
> externally with respect to the pixfmt/pixdesc.

yes
its just seperating "how to store" from "what is stored"


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

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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