[vlc-devel] Re: Fwd: [Possible endian bug in video_chrome/video_output]

[Benjamin Pracht]

Le jeudi 23 février 2006 à 09:59 +0100, Alexander Gall a écrit :

> > 
> > I have built the vlc svn snapshot 20060217 for Solaris 11 on SPARC.
> > It mostly works but the video output (x11 and opengl) is broken.  With
> > x11, the display is monochrome black/red and with opengl it looks like
> > some colors are missing or swapped.  The visual I'm using is 24
> > planes/32bpp, see attached output of xdpyinfo (screen #0).  Note that
> > the "image byte order" is big endian (MSBFirst).
> > 
> > I experimented a bit and found that the colours look ok with opengl
> > when I reverse the byte ordering of the 32 bit word in the macro
> > CONVERT_Y_PIXEL in modules/video_chroma/i420_rgb.h (see attached
> > patch).  I have attached the output of vlc run with -vvv as well.
> > 
> > I can't say whether this is a genuine bug or whether vlc just fails to
> > detect the properties of my display correctly.  The videou output and
> > chroma code never seems to check the image byte order of the display
> > (i.e. there's no reference to the symbols MSBFirst/LSBFirst), which
> > seems a bit surprising to me. In any case, I hope that my hack is
> > enough to track down the source of the problem.
> > 
> > BTW, the mpeg2dec utility that comes with the mpeg2dec library
> > displays video correctly with both x11 and opengl output using the
> > libmpeg2convert library.  This library also has the advantage to
> > support the SPARC VIS instruction set.  Maybe it would make sense for
> > vlc to use it as well.

I'm really not sure with x11 (btw, are we talking about x11 or
xvideo ?). The x11/xvideo vout works on linux PPC, which is big endian
too. I haven't tested the glx output on linux PPC, since I don't have
any accelerated drivers there. I should test with mesa some day...

-- 
BigBen

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