[mythtv-users] Appropriate video modes for widescreen TV-out

[Cory Papenfuss]

> I feel like I am missing some of the fundamentals on how the TV-out
> works on video cards - is it directly affected by modelines, or is it
> basically doing something a bit on its own so only partially affected by
> the modelines (ie resolution set by modeline, but the scan rates etc
> done elsewhere)?  I'd really appreciate any pointers to basic
> information on this.

 	Sounds like you already have a better grasp on it than most (your 
latter comment is more correct).  TVout is loosely related to modelines, 
but in the end the tvout chip (or part the the GPU that is doing tvout as 
in nvidia) is what's responsible for the display.  You should at least run 
a modeline that's got the correct number of scanlines (i.e. 576 for PAL) 
so you don't have to do any vertical rescaling.  Unfortunately, most cards 
will scale it anyway (think over/underscanning).  If I *had* to use tvout 
in PAL-land, I would try to disable all over/underscanning, and run a 
modeline that's 768x576 at 100Hz.  The NVidia driver is supposedly clever and 
will disable the scaler in that case, but I've not verified it.

>
> The specific problem I have is getting an appropriate X config for a
> NVidia GeForce MX4000 driving a UK PAL-I widescreen TV through SVideo
> (initially - I may move to direct VGA->RGB/SCART if the quality via
> SVideo is grotty).  Ideally I want to run the beast as widescreen with
> the right sort of aspect ratios.
>
 	That can be a pain, but the SCART quality can be quite a bit 
better.

-Cory

*************************************************************************
* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
*************************************************************************