A.w. Smith
12-02-1993, 06:13 AM
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* The A.T. Jousse Research Laboratory *
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* Andrew (Drew) Smith, Ph.D. | Assistant Professor, U of Toronto *
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ORIGINAL BIOMCH-L POSTING =================================================

Dear BIOMCH-L Readers,

We have a Panasonic (National) AG-7350 VCR with an RS-232C add-on which allows
us to operate the VCR from a microcomputer. We are especially interested in
taking advantage of the time code generator to control our digitising of

The product manual is quite helpful, but it lacks sufficient information to
do all the things we want. I suspect it is a translation from its original
language as well.

Are any of our readers famililar with this issue? Can anyone suggest a source
of 'generic' subroutines, perferably in BASIC or Turbo Pascal, which can help
us to get up to speed here? Any and all suggestions gratefully accepted (and
any pertinent info will be posted here as a summary).


Drew Smith PhD

REPLIES RECEIVED TO DATE ================================================== =

Date: Fri, 26 Nov 1993


It was very nice to see your latest posting about VCR, because I
think you may be able to help me in a problem which seems to have
a solution but difficult to decode from all the technical and
commercial jargon.

My problem is that I want to be able to record the patient's gait
, from multiple views if possible, display these recordings on
different windows on the screen, overlay graphics, i.e. graphical
representations of measured parameters such as forces/moments, on
each window and on each "Frame", and finaly store these on a VCR
to enable repeated examinaton of the patient's analysis by clicians.

I am faced with the problem of real time digitisation of video frames
which means no PC will be fast enough to store the digitised frames at
25 Hz. The other problem would be to record the modified images, i.e.
those with the graphics, onto a VCR at 25 Hz (i.e. real time rate).
Apparently it is not possible to DAC a digitised frame for writing to
VCR fast enough (i.e. at a rate of 25 Hz). the only option is therefore
to stop/pause or freeze the VCR at individual frame positions to allow
the computer to DAC the frame.

IS this possible ?

By the sound of your question sent to the list it seems that you have
experiences in this area which you might be willing to share.

looking forward to your comments.


Hamid Rassoulian
Senior Medical Engineer
Southampton General Hospital

Date: Fri, 26 Nov 1993
From: Paul Guy

Hi Drew,

Do you have the pages from Panasonic for their 'computer control
codes'? If you have the codes to drive the serial port with, then the
programming of the VCR is quite trivial, depending on how fancy you want
to get.
We bought an AG6750 (time lapse VCR) and it took some fairly forceful
persuasion to squeeze the info out of Panasonic. You should have
someone handy who understands Japanese. A lot of the technical info is
half-and-half English and Japanese.
For an application this off the track, I think you're being overly
optimistic about getting hold of 'generic' software.
Is your time code generator a SMPTE VITC type? Can you access single
fields with your VCR? Are you digitizing from video at the normal
playback rate, or digitizing from stopped motion?
If your time code is SMPTE and you are digitizing at the normal frame
rate, I doubt if you need much programmability, since you can trigger
the digitizer from a SMPTE reader.
If you are using SMPTE, I'd be curious where you got this stuff from
(and how much) since a year or two ago when we looked into this type of
data collection, most video houses were abysmally ignorant of the
technique. Since then we have been using Optotrak hardware, and the
setup is MUCH easier, 10-15 minutes as compared with 3-4 hours for 3D
video. Since I can 'genlock' the Optotrak with a video sync signal, it
behaves much as a video camera, except giving us on-line 3D accurate
coordinate data.
We have a number of programs to handle video data, to correct for tilt
barrelling etc,to track missing markers, to manually fix botched data.
They are all in 'Microsoft C (v7.0)'. Non of the programs actually
digitize directly from the VCR - even with a time base corrector, the
quality was too low or the sync to rough to get good coordinates. The
system we have (the old video one) would be accurate to a few
millimetres in a 2m X 3m view.
Are you building a system from the ground up, or are you tying this
system into a commercial unit?


Date: Fri, 26 Nov 1993
From: Brett Lee

Hi Drew,

I don't have any knowledge of the Panasonic AG 7350 VCR, but I have
written some programs to control a Panasonic AG 1960 VCR from a PC. This
had to be done via an editor as the 1960 does not have a serial port.

Currently we use a SMPTE time code generator to dub time code on the
audio track and/or put a time code "window" on the video tape. The
programs I've written are in "C".

If you have any general questions with regard to this type of programming,
feel free to contact me.

Brett Lee
Purdue University
brettlee@vm.cc.purdue.edu Internet

Date: Mon, 29 Nov 1993
From: RKUMMER@pitvax.xx.rmit.edu.au

Hi Drew,

I've just read your letter to BIOMCH-L about programming a AG-7350.
We have exactly the same model VCR with the RS-232 add-on which we use with an
eye-movement monitoring system, and we connect the VCR to an IBM compatible
computer (80286). I know what you mean abuot the documentation; it took me
a long-long time re-reading it to get some sort of handle on it. I written
a few program using turbo-c and they seem to work OK. There are a few
things about the system that don't seem quite right, like I've never found
out a simple command to do a single field step but I get around that
problem OK. Also, it seems that I can only get the time-base control to
talk in terms of frames rather than individual fields. I can certainly give
you a more complete picture of how we use the system, and some example
programs to drive the VCR. If you want to mail me and give me a better
idea of what you want to do I'll get back to you, or latter on today I can
chase up some listing for you and email them (the problem being that I have
on ever written them for my own use so the inline documentation is not to

Ross Kummer
Technical Officer, Royal Melbourne Institute of Technology,
Melbourne, Australia.

Date: Mon, 29 Nov 1993 15:21:00 -0500
From: Noldus Information Technology bv

Dear Dr. Smith,

We have a lot of experience with programming video cassette recorders, video
timecode readers, tape controllers, etc. We have developed a "Video Tape
Analysis System", which includes software support for a wide range of
professional VCRs, including the Panasonic AG-7350 with AG-IA232TC interface.
However, since this is a commercial product, we cannot distribute the source
code of the software routines which control the VCR and timecode hardware.
I am not aware of any general public-domain libraries that serve your purpose.

We would be happy to send you information about our software products, but
that may not be what you are looking for. Please don't think that all we want
is sell you a product - we are also eager to share technical experiences.

I hope that this is of any help for you.


Lucas P.J.J. Noldus, Ph.D.
The Netherlands


Date: Sun, 28 Nov 1993
From: Christian_Gottschling@infothek.fido.de (Christian Gottschling)

* Weitergeleitet aus 'Biomch-L' (Biomch-L)

Hi A.W.!
In a message of 28 Nov 93 A.W. Smith wrote to Alle:

AWS> The product manual is quite helpful, but it lacks sufficient
AWS> information to

Do you have a list of codes, that the vcr accepts?

AWS> of 'generic' subroutines, perferably in BASIC or Turbo Pascal, which

You `only` need some IO subroutines for the RS-232 for output of
the vcr-control-sequences. I don`t have such subroutines, but I
think, you could find this in some ftp-sites.

AWS> any pertinent info will be posted here as a summary).

Thanks, I`m interested in the command-list for the vcr.

MfG, Christian

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