[mythtv-users] Configuring XFree86 for TV out

Shaun Jackman sjackman at telus.net
Sun Aug 15 17:58:08 EDT 2004

> > 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

Thank you! This is exactly the information I was looking for. Is there
a list of the standard XFree86 Screen -> Display -> Modes online
somewhere? For example, if you use "640x480" do you get the standard
60 Hz you listed above? What does "ntsc_640x480" give you?

Here's the XFree86 Monitor section I'm going to use for the TV
display. I simply picked two narrow ranges that encompass the
640x480 @ 60 Hz display mode. Look good?

Section "Monitor"
	Identifier	"TV"
	HorizSync	30-35
	VertRefresh	55-60

My display manual lists 640x480 @ 60 Hz as

	Resolution 640x480
	Type VGA
	Horizontal Scan 31.469 kHz
	Vertical Scan 59.940 Hz
	Polarity -/-
	Pixel 25.175 MHz

What's the reason for the discrepency in the pixel clock (25.17 MHz
vs. 25.175 MHz). Simple rounding error? (This is just my curiosty
being spoken aloud. Feel free to ignore the question.)


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