From: johnc@yuma.ACNS.ColoState.EDU (John Cooley)
Subject: Re: Need expert advice on VCR choice!
Summary: You probably can't afford what you want
Date: Tue, 26 Jan 1993 23:58:12 GMT
Organization: Colorado State University, Fort Collins, CO  80523
Followup-To: comp.graphics.animation

In article <C12MAI.6Ls@news.cso.uiuc.edu> jas37876@uxa.cso.uiuc.edu (John A. Slagel) writes:
>    I need a VCR with these qualities:

>    1. Can be controlled by IBM PC, either serial or otherwise.
>    2. Needs SVHS capability... can be only B&W if it makes a difference.
>    3. Needs to be able to record a single frame, and tell the 
>       computer what the frame number was so that we can synchronize
>       the picture with a label.
>    4. Needs to be able to record 5-7 random frames in a second.

>    The reason I need this is because I would like to drive 30-50 mph
>    down the road, have a computer recording distance, and every 10 ft
>    it would have the VCR record 1 frame, and the computer would record
>    the frame number and distance... That way, if I want to see a shot
>    of 3754 feet past the starting point, I would know exactly
>    what frame to go to... Hopefully, even be able to have the computer
>    tell the VCR "Go to frame 53254".  

>    Is this possible, and what VCR should I buy?

A rather special problem, indeed!  You forgot to specify that the whole
set-up needs to be vehicle mounted and, therefore, battery powered.  I
will be surprised if you find anything.

In general, a number of decks available from Sony, JVC and Panasonic
satisfy requirement number 1.  As far as I know, none of them are
battery powered.

Most of these decks are S-VHS.  Sony makes remotely controllable Hi8 decks.
They are all color.

For number 3, you need time code, which doesn't label the frames in exactly
the way you had in mind, but it does uniquely identify each frame for later
access.  The algorithm mapping time code to your distance wouldn't be hard
if you could get number 4, but on a tape device, achieving number 4 is
unlikely.

Number 4 is the sticky one.  A deck with an internal or external animation
controller needs to preroll for each recording sequence, which, for you, is
each frame you shoot.  This takes several seconds, so you aren't going to get
5-7 frames per second.  A slightly different breed, a time-lapse deck, does
not need preroll, but most of them are built for security use and lack either
time code or RS232 control or both.  And they don't go fast enough to do
5-7 frames per second, at least not under arbitrary remote control.  Tape
motion is _slow_!  Decks run at 30 frames per second or they run, at best, at
one frame per several seconds.

The only device which _might_ be able to record 5-7 frames per second under
remote control is a laser video disc, since no preroll is required.  And I'm
not at all sure that even one of these would be fast enough.  And I think 
they all require AC power.  And the cheapest one on the market is still well
over $10,000.  But they do employ either time code or the frame numbering
you have in mind.

I think a laserdisc is your only chance.  If you want to forget about the
every 10 feet business and simply use time lapse, many cameras have time
lapse built in.  I suspect that would eliminate the point of your work, though.

        John Cooley
Newsgroups: comp.graphics.animation