Xref: utzoo rec.video:2735 comp.sys.ibm.pc:10553
Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!amdcad!ames!ptsfa!well!rshuford
From: rshuford@well.UUCP (Richard S. Shuford)
Newsgroups: rec.video,comp.sys.ibm.pc
Subject: Re: RGB->NTSC or EGA w/NTSC
Message-ID: <4923@well.UUCP>
Date: 7 Jan 88 18:02:01 GMT
Expires: 7 Feb 88 08:00:00 GMT
References: <20857@yale-celray.yale.UUCP>
Distribution: na
Organization: Siecor Corporation RD&E
Lines: 40
Keywords: video,graphics,NTSC
Summary: Try CGA->NTSC

Response: EGA w/NTSC (20857@yale-celray.yale/freeman@yale-zoo-suned/30 Dec 87)

If you can redefine your problem as "IBM-PC-graphics-to-NTSC" instead of
"EGA-to-NTSC" you may have an easier solution at hand, one that was
implicitly provided by IBM from the start. 

The original IBM Color/Graphics Adapter (CGA) has been much maligned for
its low resolution, but the resolution was fixed at that level so as to
enable the CGA to drive a regular TV set through an RF modulator.  (It
can also be used with a regular EIA video monitor.)  The composite video
output of the CGA is very close to being an NTSC signal by itself. 

Note that I said "close".  The signal varies somewhat from the nominal,
but if you have access to any amount of professional video equipment,
you may be able to feed a CGA signal through a "proc amp" and come out
with a rendition of your graphics image containing corrected sync, color
burst, equalization, pedestal, etc. 

You didn't say what you want to use the signal for, but if you are not
planning to broadcast it, you might even get away with not using the
proc amp.  If you do want to broadcast it, discuss the matter with one
of the engineers at the broadcasting concern.

It won't be EGA resolution, but some resolution would have to be subtracted
from an EGA signal anyway for it to squeeze into NTSC bandwidth.

You don't say precisely what EGA card you possess, so I don't know if
you have one that can be operated in CGA mode to emit an appropriate
composite-video signal.  You might have to invest in a real CGA card,
for which the going price seems to be around $55 U.S. (from
Priority-One Electronics, for instance--see advertisements in BYTE).
Or you could find somebody with a CGA setup who'd like to trade for
your EGA.... 

.....Richard S. Shuford
     Siecor Corporation RD&E, Hickory, NC 28603-0489
     7 January A.D. 1988
     UUCP: {ptsfa, hplabs}!well!rshuford  (at present)
     BIX: richard
     VMSnet: (coming soon to a VAX near you)