NTSC output from Suns and other hi-res workstation monitors (L

[Bob Tomlinson]

in article <8905042046.AA22765 at cs.utexas.edu>, pcinews!observer at cs.utexas.edu says:
> My company is looking for some type of device to allow us to capture the
> images on a 386i/250 screen and convert them to NTSC (US television)
> devices, such as a common video recorder.

The following is my opinion from trying out all boxes except the YEM box
and the new Lyon-Lamb box (but hearing about them).  I am VERY new to
video (NTSC is mysterious and bizarre to people from the digital world) so
I may have some of the following incorrect.  If so, please forgive me and
correct me.

Also, note that this is a FAST moving technology right now.  My comments
are likely to be obsolete at SigGraph and certain to be obsolete by the
next NCGA and NAB.

Most of the boxes are also available in PAL versions for people outside
the US.

The following are the companies that make such boxes (in aproximate
order of perceived quality.  Note that cost and quality don't
necessarily coorelate.):
	Lyon-Lamb
		California: (818) 843-4831 or
		New Jersey: (201) 530-0501
	Photron
		Distributed by Electro Communication Systems, Inc
		(214) 358-5195
	RGB Technologies
		(415) 848-0180
	YEM (Yamashita Engineering Manufacture)
		Distributed by Grunder and Associates
		phone number ???
	Folsom Research, Inc.
		(916) 983-7236

Actually, I think you can get several of the different boxes from Electro
Communications Systems (see their number under Photron above).  We found
them to be VERY knowledgeable, helpful, and friendly.

The Folsom, YEM, and RGB Technologies box all take the entire screen and
convert the greater resolution of the Sun or other workstation to the
lesser resolution of NTSC.  You necessarily loose resolution.  Of these
the RGB Technologies box looks best.

The RGB Technologies box does one thing that none of the other boxes do
(not even the Photron and Lyon-Lamb boxes): it can merge a NTSC video
source with the hi-res source and put the merged video on its NTSC output.
We haven't figured out a real utility for this feature for our
applications, but it's neat.  Possibly you can use it in place of a
digital effects box if you only need chroma key (put a picture of someone
in the corner to talk about what's being displayed).

Lyon-Lamb and Photron have a couple boxes out.  The new Lyon-Lamb is the
box I'm refering to (the one introduced at NAB).  The old one didn't
operate at full video rates (30 frames per second).  The new Photron box
I'm refering to has "EZ" appended to the part number (the old one did line
dropping instead of line averaging).  These are also just out (only a
couple boxes are in the US).

The boxes by Lyon-Lamb and Photron can do what the first set of boxes 
do (except for RGB Technologies video mixing) and can also capture a
smaller NTSC size window at full resolution.  This allows you to see
a portion of your screen without any loss of resolution.
Lyon-Lamb/Photron differences:
	- The Lyon-Lamb box comes standard with an RS-232 input to
	  the box to control operating parameters (amount of smoothing,
	  partial screen/full screen mode, what portion of the screen
	  to capture when in partial screen mode, etc).  The Photron
	  box doesn't have that standard although I understand it can
	  be added; apparently they dropped it because it wasn't used
	  on older boxes (although it's important to us).
	- The Lyon-Lamb box has adaptive circuitry to adapt to adapt to
	  different hi-res monitors (see below for a description of this).
	- The Lyon-Lamb box can take as input not only a NTSC
	  resolution sized window on the workstation, but can also tak
	  an arbitrary sized window (whatever aspect ratio) and do a
	  reasonable job at putting it into a NTSC signal.  I've not
	  seen this, but it sounds really neat.
	- The Lyon-Lamb box is said to do a better job (better quality)
	  to others who have seen both it and the Photron box.
	- The Lyon-Lamb costs less than the Photron box.

Features/Things to be careful of:
	- Be careful for boxes that simply drop lines instead of doing
	  averaging/smoothing.  Otherwise if you have a one pixel wide
	  line on a raster scan that is to be dropped it will be gone
	  on the NTSC.
	- Can you control the amount of smoothing?  Hi-res monitors are
	  usually ~60KHz monitors.  NTSC video is 30KHz.  Therefore these
	  boxes draw alternating horizontal traces down the screen
	  (interlaced).  If you have a black horizontal line and then a
	  white horizontal line these will be drawn at alternating times.
	  You will therefore see a beating between the two lines.  This
	  can be negated by smoothing (averaging neighbor pixels with
	  a drawn pixel).  The more smoothing means less beating, however
	  smoothing fuzzs the lines (or characters) making things less clear.
	- Is the internal encoder a quality encoder or do you need an
	  external encoder?  An external Farujda (sp?) encoder (high quality)
	  is ~$8K by itself.
	- When seeing a demo, is it going to a normal monitor or is it
	  going to a SVHS (Super VHS) monitor (more scan lines)?  Does
	  the box have an SVHS out?
	- How do you change from monitor type to monitor type (Sun to
	  uVAX, etc)?  Some have adaptive circuitry.  Some you must
	  change a crystal.  How hard is it to change the crystal?
	  I have heard claims that the adaptive circuitry is less
	  reliable and gives you a lower quality image (although
	  I haven't examined that).

 - Bob Tomlinson
   tomlin at hc.dspo.gov

Bob Tomlinson -- tomlin at hc.dspo.gov  --  (505) 667-8495
Los Alamos National Laboratory  --  MEE-10/Data Systems