[FFmpeg-devel] [RFC] RGB32 pixfmts cleanup

[Michael Niedermayer]

On Sun, Mar 22, 2009 at 04:20:38PM +0100, Stefano Sabatini wrote:
> On date Thursday 2009-03-19 01:25:19 +0100, Michael Niedermayer encoded:
> > On Thu, Mar 19, 2009 at 01:12:46AM +0100, Stefano Sabatini wrote:
> [...]
> > [..]
> > > @@ -91,8 +89,10 @@
> > >      PIX_FMT_NV12,      ///< planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 for UV
> > >      PIX_FMT_NV21,      ///< as above, but U and V bytes are swapped
> > >  
> > > -    PIX_FMT_RGB32_1,   ///< packed RGB 8:8:8, 32bpp, (msb)8R 8G 8B 8A(lsb), in CPU endianness
> > > -    PIX_FMT_BGR32_1,   ///< packed RGB 8:8:8, 32bpp, (msb)8B 8G 8R 8A(lsb), in CPU endianness
> > > +    PIX_FMT_ARGB,      ///< packed RGB 8:8:8, 32bpp, (msb)8A 8R 8G 8B(lsb), in CPU endianness
> > > +    PIX_FMT_RGBA,      ///< packed RGB 8:8:8, 32bpp, (msb)8R 8G 8B 8A(lsb), in CPU endianness
> > > +    PIX_FMT_ABGR,      ///< packed RGB 8:8:8, 32bpp, (msb)8A 8B 8G 8R(lsb), in CPU endianness
> > > +    PIX_FMT_BGRA,      ///< packed RGB 8:8:8, 32bpp, (msb)8B 8G 8R 8A(lsb), in CPU endianness
> > >  
> > >      PIX_FMT_GRAY16BE,  ///<        Y        , 16bpp, big-endian
> > >      PIX_FMT_GRAY16LE,  ///<        Y        , 16bpp, little-endian
> > 
> > the description is wrong, these are not in cpu endianness
> 
> Hi,
> 
> checking again the patch, the define change will broke regression,
> since "rgb32", "rgb32_1" and friends have different meanings according
> to the endianess of the system.
> 
> So we have:
> 
> name      |   BE   |  LE
> ----------+--------+------
> "rgb32"   |  ARGB  | BGRA     
> "rgb32_1" |  RGBA  | ABGR
> "bgr32"   |  ABGR  | RGBA
> "bgr32_1" |  BGRA  | ARGB
> 
> That is a test for the format "rgba" will work differently in LE and
> BE systems.
> 
> A possible solution would be to extend the avcodec_get_pix_fmt() so
> that it will recognize also the "rgb32", "rgb32_1", etc. names, and
> will return the right pixel format according to the previous table.

its ok to make t recognize "rgb32" "bgr32"


> 
> A cleaner solution may be to extend the PixFmtInfo/AVPixFmtDecriptor
> to support also one or more aliases for each pixel format name.
> Then we could define the various alias for "rgba", "bgra", etc
> according to the system endianess.

iam against ading a alias field that will be unused by 98% of the
entries and will complicate all code

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

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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