[Intel-gfx] VGA to PAL RGB

[Thomas Hilber]

On Thu, Jul 24, 2008 at 12:21:14PM +0200, Thomas Elsen wrote:
> I'm trying to get the following modeline to work with my Mythbuntu. This 
> modeline should be perfect for television sets that understand PAL.
> 
> Modeline "768x576pali" 14.76  768 789 858 944  576 580 583 625 -hsync 
> -vsync interlace
[...]

> The problem with the current drivers is that the minimal dot clock is 
> defined as 25Mhz. I'd like to know if this is a hardware limitation and, 
> if not, what should be done to run the clock at 14,76Mhz.
[...]

For my current project

english:
http://linuxtv.org/pipermail/vdr/2008-July/017347.html

german:
http://www.vdr-portal.de/board/thread.php?threadid=78480

I experiment a lot with VGA->SCART adaptors. In the meantime I
get excellent picture quality on Radeons like (7000, 9200SE, 9250,
9600SE, IGP-9100). This is because no deinterlacing at all takes place
any more. I route the untouched fields from softdecoder straight through
to the VGA port! I developed a new synchronization mechanism that avoids 
any field loss. Please see links above for more information.

Yesterday I started to port this thing to intel DDX. Please find
attached a patch that allows you to use such low dot clocks on intel
hardware. I don't know what these limits in the standard intel code are
good
for. BTW I use a thinkpad with mobile GM965/GL960 chipset for my tests.
Maybe you must adapt the patch to your needs.

But there exist still some issues with intel-gfx and interlaced modes:

Using the overlay XV adaptor I only get a green picture...
Using the textured XV adaptor the picture is vertically stretched (if
not
doubled)...

So for the moment I stopped further activities with intel-gfx.

Maybe the situation has improved since xf86-video-intel 2.4.0. I haven't
had the time yet to give it a try.

-Thomas

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