[clug] how to set up xorg.conf for DVI overscan

Eyal Lebedinsky eyal at eyal.emu.id.au
Thu Oct 25 22:57:43 GMT 2007

I asked on the mythtv list and did not yet see an answer. Maybe someone
here knows the answer.

Executive summary:
	How do I configure a xorg.conf mode of an 1152x680 screen encased
	(letterboxed) in 1280x720 DVI timing? The smaller area must be the
	advertised viewport size, not a panning area.

	Note that DVI ignores blanking information so these tricks do not
	work. Neither does TVOverScan which is only for tv-out.

LG lied through  their teeth when they said that their HDTV (RT-52SZ8R)
is native 1280x720 - it trims a significant part of all edges, enough
to make if difficult to use in text mode. It simply never displays this
many pixels.

This cannot be adjusted, not even from the special technician menus.

I want to tell xorg.conf to send a 1280x720 DVI signal but use a smaller
area as the drawable. I do not want to just tell the wm to void the edges
or to set mythtv to run in a window (I know how to do that).

In effect I want to tell it that my TV over-scans, and it should
letterbox the screen and present a smaller area to all the applications.

Using DVI it seems that all the blanking information is simply ignored
so one cannot play with that, so letterboxing is the only option.


Eyal Lebedinsky	(eyal at eyal.emu.id.au)

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