Re: [Closed REQ 5816]: Geomview question (NTSC mode)

[daemon]

> What exactly does the NTSC video mode in the SGI version do?

Right, it changes the sync frequency, to the US standard television video rate
(30Hz, interlaced, 525 total scan lines).  And yes, it's intended for
video recording.  Some people (including us) have an external encoder which
can attach to the monitor cables, taking RGB signals at the standard rate
and producing ordinary composite video.

Specifically, it does I think the same thing as
	/usr/gfx/setmon NTSC
When you turn NTSC mode off (by typing "TV" again, or typing "0TV")
it reverts to 60Hz noninterlaced mode, just as in
	/usr/gfx/setmon 60HZ
60HZ used to be the normal scan rate for SGI monitors; however, within the
last few years they've gone to 72HZ as the default rate.  Current monitors
seem to display well at either 60HZ or 72HZ, though 60HZ flickers a bit.
Use	/usr/gfx/setmon 72HZ
to revert to that rate.


I'm not sure about PC VGA, but see the list of modes in "man setmon".
Most SGIs support PAL, and 30Hz high-resolution interlaced video, at least,
in addition to NTSC.

Geomview's "TV" command can select only NTSC and 60HZ rates -- for anything
else you'll need to use setmon (or change the source code -- see
src/bin/geomview/gl/glmain.c.  Geomview sets the display mode only if
asked explicitly -- it won't disable NTSC mode just because you quit.

Hope this tells you what you need to know.