[vlc-devel] Bug, Re: xv problems with new via cle266 chipset revision

Greg Farrell greg at gregfarrell.org
Thu Feb 9 19:36:08 CET 2006

Further to my mail below:

Have discovered with help from Sam (thanks) that libmpeg2
does not respect the driver pitch values. So as the via driver returns
an xv surface of 736x576 for a request of 720x576 a mpeg decoded via
libmpeg2 will fail.

Also have subsequently discovered that using any of the deinterlace
filters also results in garbled output under these circumstances. The
distort filter works fine however :)

I managed to produce a work around for me that involves me modifying the
xv code's XvShmPutImage() so that it mangles the 736x576 buffer back to
a 720x576. This works for me but is a hard-coded, useless for the
general public hack.

Using ffmpeg to decode instead of libmpeg2 works, but you still can't
use deinterlace filters without mangling the output.

Just posting this here in case anybody else is experiencing the same
problem and finds my previous mails. Anybody who's driver bumps to
multiples of 32 like the unichrome does will experience these problems I


On Tue, 2006-02-07 at 14:17 +0000, Greg Farrell wrote:
> Hi,
>   we've been happily using vlc in xv mode with the via cle266
> (unichrome) chipset and the unichrome.sf.net driver.
> However we just got a new motherboard and the chipset revision of the
> cle266 has been bumped from 17 to 18. This caused locks in X under xv so
> we had to upgrade to x.org 6.8.2 and the latest unichrome (also
> openchrome) drivers.
> These fix the locks but the mpeg output is distored in vlc.
> Output from all mpeg files is correct in xine and mplayer using xv,
> however we're happy using vlc and don't intend to change. We really
> could use some help working around this problem though.
> The output of the mpeg movies (720x576 res, but AR 4:3) is badly skewed.
> At the bottom of the vout there are 5 or 6 lines of flashing mostly
> green but sometimes multi coloured junk. The rest of the display looks
> as if it's been wrapped somewhere other than at the edges and perhaps
> even rotated slightly, although that may just be me being confused.
> I talked to the author of the unichrome driver about this and he
> believes it's a problem in vlc's xv code. Our subsequent discovery that
> xine and mplayer display properly seems to agree with this, although i'm
> open to all suggestions.
> This happens with both our older 8.4 test1 and the latest source release
> tar from the website.
> Can anybody help, please?
>     Greg

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