[mythtv-users] Minor Screen Refresh Visible
dsr-myth at tao.merseine.nu
Wed Jul 30 13:58:20 UTC 2008
On Wed, Jul 30, 2008 at 09:28:44AM -0400, C.T. Paterson wrote:
> 2008/7/30 Dan Ritter <dsr-myth at tao.merseine.nu>:
> > On Wed, Jul 30, 2008 at 08:39:54AM -0400, C.T. Paterson wrote:
> >> 2008/7/30 Petteri Matilainen <pmatil at gmail.com>:
> >> > VGA->SCART adapter cable. Do I need to modify the xorg.conf modeline?
> >> > Any help is greatly appreciated.
> >> My experience does not suggest I had a modeline problem - but it's
> >> possible. Where did you get yours from? I've got an LCD HDTV, and
> >> some of them are known to supply incorrect modelines to Xorg (google
> >> for a "UseEDID" xorg option). Mine appeared to be one of them, so I
> >> obtained mine by running "gtf" on the command line, and used the
> >> generated modeline in my xorg.conf.
> > You could certainly be running with a modeline that your LCD
> > does not quite like. I just acquired an LCD, and discovered that
> > the NVidia built-in 1920x1080_60 mode was horrendously
> > overscanning horizontally. The manual contained all the required
> > timings, though, and I built a perfect modeline out of that.
> If you're inclined, Dan, I'd be interested to know how. My knowledge
> of modelines is pretty slim - and while my manual has a bunch of
> information in it - I wouldn't know how to construct a modeline out of
> it (although gtf seems to have served me well). I'm merely curious.
What LCD do you have? Is the manual online? I'd be happy to
An X modeline is not black magic; it's a list of timings, mostly
in terms of pixels:
Rate HDisplay HSyncStart HSyncEnd HTotal VDisplay VSyncStart VSyncEnd VTotal
You know the HDisplay and VDisplay fields immediately: those are
the visible pixels. The Rate is the pixel clock, in millions per
second. That should be in the manual.
Manuals like to specify FrontPorch, BackPorch and Sync;
considers there to be offsets to add to the previous entry, so
HSyncStart = HDisplay + FrontPorch
HSyncEnd = HSyncStart + BackPorch
HTotal = HSyncEnd + Sync
Then, for vertical timing, it works out the same way.
Adding +/- HSync and +/- Vsync flags indicates the polarity of
the signals; again, that should be in the manual.
http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference.
When freedom gets lots of exercise, it protects itself.
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