[mythtv-users] Fixing overscan

Chris Ribe chrisribe at gmail.com
Fri Dec 11 06:34:46 UTC 2009

On Thu, Dec 10, 2009 at 8:06 PM, Nick Rout <nick.rout at gmail.com> wrote:

> On Fri, Dec 11, 2009 at 1:00 PM, German Rodriguez <callmegar at gmail.com>
> wrote:
> > You can run it from a VNC session, and do the realtime adjustment, the
> > problem is that the VNC session has no overscan, so you won't be able
> > to see the adjustment in your computer monitor, you would have to
> > adjust in the PC, go look into the TV go back to PC adjust a little
> > more, you get the idea, but it will work.
> From a laptop sitting in front of the screen can be quite good.
> _______________________________________________

I've just recently made peace with my latest frontend/monitor combination
after an epic 6 week struggle to find suitable settings.  I haven't
fulfilled my ambitions, but I've decided to live with what I have at this
point.  I'm using an(a?) nvidia 9400M chipset and the 190.42 driver.  I was
extremely pleased to find the overscan slider had returned to
nvidia-settings since I had last used it, but when all is said and done I'm
not using it.

Most of my problems stem from my oddball monitor - it's a rear projection
CRT HDTV with a DVI input that is capable of both 720p and 1080i native
resolutions.  My dream has long been to get everything configured so that I
can watch any HD programming at its native resolution, but I've given that
up at this point due to field order issues with interlaced content and an
apparent incompatibility between xrandr and the latest nvidia drivers.

Back on topic, I suffer from horrible overscan.  With the stock settings,
the "Next" and "Previous" buttons are completely off screen on all setup
pages.  At first I enabled the nvidia overscan setting to compensate for
this.  This was when I was still trying to get 1080i to work, and I soon
realized that turning on overscan compensation destroyed the picture quality
in 1080i.  The overscan compensation is just downscaling in the GPU.  It is
pretty good for cheap realtime downscaling, and not too noticeable during
720p video playback, but it results in significantly blurrier text in menus
and on the desktop.

It completely screws up interlaced playback, but it isn't like interlaced
playback actually works otherwise.  I can hardly blame nvidia for not
adequately supporting my archaic monitor, I'm probably one of about 17
people worldwide who actually still has a 1080i monitor.  It may not even be
an nvidia issue anymore.

At any rate, I finally settled on a custom 720p modeline that reduces the
overscan as much as possible, and the lovely separate GUI / playback
resolution feature of .22.  I have my GUI resolution set at 1152 x  648 t
omatch the visible portion of the screen.

If anyone out there knows the secret to smooth 1080i playback to a native
1080i display, please share.

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