PC Controlled VCR
Ross McConnell
or parallel port from a PC? I just want to give basic commands
such as RECORD, STOP, REWIND, etc, under program control.
Larry Lippman
I know of VCR's controlled by PC's for interactive education,
product ordering, etc. - such as the NCR INteracTV (tm) - but that
is probably not what you want (these systems are generally play-only).
However, it would be fairly easy to build what you want. Take
a VCR with a _wired_ remote - such as the Panasonic NV-8420. The wired
remote consists merely of a keypad connected to a cable. Use a reed
relay matrix to replace the keypad and provide isolation. Connect an
octal latch to a parallel printer port, using the printer strobe line
to reload the latch. Using suitable relay driver IC's, drive the
select relays from the octal latch.
All you have to do is write bytes to the printer port to
control the VCR. I have already done this to a Panasonic NV-8420,
and have the following commands available: STOP, PLAY, RECORD, FORWARD,
REVERSE, SEARCH FORWARD, SEARCH REVERSE, SLOW, PAUSE, and FRAME ADVANCE.
I actually used optoisolators instead of reed relays - but the reed
relays are a safer bet unless you feel totally comfortable working with
the VCR logic.
You can build this entire circuit for less than $ 20.00 in
components.
If you use the above suggestion, don't forget that you have to
write a null (00H) to the printer port after each command (except for
the SEARCH commands), since the remote keypad is momentary in nature.
<> Larry Lippman @ Recognition Research Corp., Clarence, New York
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b...@cs.ucla.edu
There have been a lot of requests for single frame recording and computer
control recording of images onto video tape. This is another in the
sequence. The problems are still not solved at a reasonable price. Control
with some other facilities is available from:
GYYR Corporation
1515 South Manchester Ave.
Anaheim, CA 92802
This company specializes in time lapse recording (for security applications)
using video tape. Their best machine has an RS232 interface, it is not
clear however that the RS232 interface (which is an option) also combines
with the color option. They do not give a price for both combined. If they
do combine, the result would have the order number TLC2051-C-232, and the
price will be in the neighboorhood of $4,000.
In answer to the people who want single frame recording and synchronization
with a PC monitor this machine will also record single frames, as long as
the frames are generated faster than every 2.5 minutes. It will also require
conversion of the RGB to NTSC and a Genlock in the PC. I have no idea how
well this scheme would work but somebody with money might try it out and let
us know. I would sure like to find a cheap way to do animation. Not that
5-6K is cheap, but it is the cheapest way I have heard of yet.
Because of the 2.5 minute restriction, many images will have to be precomputed
and stored on either a hard disk, floppys, or tape cassette to do real
animation. This is a direction well worth exploring.
I talked to the people at GYYR and they seem receptive to this new market,
someone with money could really get something started.
BUZ
Alastair Mayer
I'd be interested in such a gizmo myself (n-year, n-event programability!)
but haven't heard of such off-the-rack. However, hardware-hacking a device
that makes use of a VCR's normal remote control shouldn't be too hard -
you could hack the actual remote controller to command switch closures
via a serial port. Ciarcia's column in "BYTE" a couple months back
described a generic, programmable, IR controller that you might borrow
circuits from.
--
Alastair JW Mayer BIX: al
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