foo@titan.rice.edu (Mark Hall) (11/21/89)
Hello Netland,
I need some help in configuring a system to record computer
graphics output to videotape. I have little knowledge in this area.
We have various machines where the original calculations will
be made. Most of these are connected by an ethernet. This is a
university environment, and the hope is to find a solution which
will enable many groups on campus to use the equipment. Reality,
in the form of monetary limitations, etc., may force up to accept
a solution which makes access difficult for almost all groups
(except one).
From what I could find on short notice, here is my understanding
of our options:
The one machine scenario: The recording setup is tied to a single
computer screen. An encoder takes the RGB output from the computer
(either an approximately 525x800 region, or full-screen averaged down)
and produces NTSC output. A video recorder capable of single-frame
recording and controllable by an RS422 (HPIB) interface is used to record
a frame at a time. I see references to a sync generator but am not sure
what its purpose is (NTSC doesn't have a sync pulse?).
The many-machine scenario: Essentially the same, but the encoder
is connected to one of several computer terminals and must be able
to handle lots of different line rates for its RGB input.
For our purposes, this would have to be automatic, because no one is
going to be available to tweek the encoder for each machine as needed.
We would also need a way of controlling the VCR from many machines:
either the control should be RS232 or buy an RS232-to-RS422 adapter
box. I saw one for $295. Of course, a program would have to be written
for each machine to control the VCR. This solution would also involve
physically moving the encoder and VCR for each project.
The Ethernet scenario: Some sort of box sits on the ethernet. Pictures
are sent to it. It produces NTSC output and (hopefully) controls the VCR.
Any machine on the net can then conceivably create the frames for a movie.
They only need to be able to create files of the correct format and sit on
Ethernet. I have seen a mention of an Abekas box recently which describes
this sort of setup, under the question of real-time display and storage.
We have no need of realtime, and the price is probably far too high for us.
I was wondering if an Amiga with ethernet card and NTSC driver might not
be suitable for this.
So, the questions are:
Have I got the basic idea?
What is the sync generator needed for?
Who are some (VCR, controller, encoder) vendors I should talk to?
Vendors to avoid?
How much are writable digital disk setups? What kind of controls
are available? How many frames can be stored? Who are the vendors?
For the VCR: would UMatic be better for us? We could copy to VHS
for informal presentations, etc. but it would be nice to
have the option of producing a better tape format (like for my
upcoming SIGGRAPH debut :^) . Who do I talk to about computer-
controllable VCRs?
Is there a cheap way to get the Ethernet scenario to work? Are the
NTSC boards for the Amiga high quality output? Is there an easy
way to remotely run jobs on the Amiga? (RS232 from an adjacent
machine would be OK if remote procedure calls from Unix are not
an option)
- mark