NTSC

freeman@yale-zoo-suned..arpa (Andrew C. Freeman) (12/31/87)

   I'm looking for an inexpensive way to get EGA graphics from
   a PC to videotape.  There seem to be two ways to achieve this.
   I already have an EGA card but it is not NTSC compatible, therefore
   the first way is to buy an RGB->NTSC converter.  The second way
   is to start from almost scratch and buy an NTSC compatible EGA
   card.  I would welcome suggestions, make that cost conscious 
   suggestions, regarding either of these alternatives.

                         Thanks,
                          Andy

rshuford@well.UUCP (Richard S. Shuford) (01/08/88)

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)