[mythtv-users] Configuring XFree86 for TV out

[Cory Papenfuss]

On Sat, 14 Aug 2004, Shaun Jackman wrote:

> Hello,
>
> I have a Matrox G550 I'm attempting to configure for TV out. So, a
> couple questions...
>
> 1. What's the the best display mode for NTSC output?
>
> How many vertical lines does NTSC really have anyways? Can I set up a
> display mode for the NTSC television's actual native resolution?
>
 	With a normal TVout card, you probably can't.  Searching online found 
this as "standard VGA 640x480 at 60Hz"

Modeline "640x480"   25.17   640 656 752 800   480 491 493 524  -hsync -vsync

I would venture to say that short of building the monstrosity that I did to 
make sure it's standard, running a 720x480 mode at NTSC frequencies (480p, not 
480i since VGA monitor or your eyes won't like it) would yield something like 
this found online:

ModeLine "NTSC-DVD-59.94p" 27.0 720 736 800 858 480 484 492 525

That gives 27e6/858 = 31.468 kHz = 2 * 15.734 kHz horizonally
31468/525 = 59.94 Hz vertically

If you don't like 60Hz on your monitor, you could try 3x

ModeLine "NTSC-DVD-89.91p" 40.5 720 736 800 858 480 484 492 525
47.203 kHz horiz
89.91   Hz vert

... or 4x

ModeLine "NTSC-DVD-119.9p" 54.0 720 736 800 858 480 484 492 525
62.937 kHz horiz
119.9   Hz vert


 	Like I said, you're kinda fooling yourself since the video card is 
doing a scanline conversion anyway down to 480i.  These modes just give it a 
nice multiple of the scan rate (to exacerbate any beat frequencies since 
nothing is genlocked... :).


-Cory