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

Greg Farrell greg at gregfarrell.org
Wed Feb 8 13:31:01 CET 2006

Further to the mail below:

1) If I force the xvideo-chroma to YUY2 instead of the movie's correct
YV12 a chroma transform has to take place. After this the movie actually
displays correctly although it's un-usuably jerky as too much cpu is
used up by the transform.

Whereas if I leave it as the YV12 (which as I understand it means no
chroma transform is done?) then the output from xv is still mangled.

mplayer and xine play this movie using YV12 correctly. Does this
transform fixing display point to any particular issue?

2) Also weirder still, if I transcode the mpegs from their 720x576 to
640x480, 700x560, 800x640 it will display correctly! However if I then
transcode that mpeg back to 720x576 it once again displays garbled. Is
there something special about this resolution?

All of these resolutions are 1.25:1 ratios, yet only the 720x576 does
not display correctly.

This is confusing the hell out of me, can anybody shed some light on it


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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