[mythtv-users] Modeline adjustments?

Cory Papenfuss papenfuss at me.vt.edu
Tue Aug 8 12:12:26 UTC 2006


On Mon, 7 Aug 2006, Tim Scholl wrote:

> The final frontier!  Have Myth running great I am now trying to transition
> to the HDTV display!
> 
> I found a standard modeline of 1080i and put it into my XF86Config-4 config.
> ----------------
> HorizSync 31.5 - 37.9
> VertRefresh 59 - 61
> 
> ModeLine "ATSC-1080-60i" 74.25 1920 1960 2016 2200 1080 1082 1088 1125
> Interlace
> ---------------
> 
> I startup mythtv and the dispay looks good on my monitor!!  sooooooooo...
> I attached the vga output to an Audio Authority A960 transcoder, turned on
> my HDTV, and got WALLA!!   A fantastic picture,  great color, stable, no
> jitter and looks great.
> 
> Only one problem!!
> 
> The left hand side of what should be the normal display,  is in the middle
> of the screen!!   Then rest of the display drops off at the end of the
> screen and wraps around to the other side and joins again in the middle.
> The full display is visable and clear as a bell!
> 

	You could try adjusting it to something more like this:
ModeLine "ATSC-1080-60i" 74.25 1920 2060 2116 2200 1080 1082 1088 1125

	I added 100 dots of black on the right hand side and removed 100 
dots of black on the left-hand side (i.e. changed 1960->2060 and 
2016->2116).  That should move the screen, but it won't move it anywhere 
close to half a screen width.

> Since it looks good on the monitor, why is it so far off when displayed on
> the HDTV?
> Not being a that familer with modelines, is this a modeline issue or do I
> need to look elsewhere?
> 
> Does anyone know what needs to be adjusted to get it to shifted to the left
> hand side?
> 
	You might try different combinations of [+-]hsync and [+-]vsync at 
the end of the modeline:
ModeLine "ATSC-1080-60i" 74.25 1920 1960 2016 2200 1080 1082 1088 1125 +hysnc -vsync interlace


	It definately sounds like the HDTV has having trouble finding the 
sync pulse.  Strictly speaking, HD-component requires bi-directional sync 
signals, and that's a much harder thing to generate (correctly) from RGBHV 
like VGA.  I don't know if the A960 does that, or makes the easier 
uni-directional sync.  Any jumpers to twiddle on the transcoder?

-Cory

-- 

*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA                                       *
* Electrical Engineering                                                *
* Virginia Polytechnic Institute and State University                   *
*************************************************************************



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