Xref: utzoo comp.sys.amiga:46710 comp.sys.atari.st:23505
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!ccavax!lmrc!hassinger
From: hassinger@lmrc.uucp
Newsgroups: comp.sys.amiga,comp.sys.atari.st
Subject: Re: Genlock inquiry
Message-ID: <3228@lmrc.uucp>
Date: 2 Jan 90 15:13:06 GMT
References: <678@alias.UUCP>
Organization: Liberty Mutual Research Center, Hopkinton, MA
Lines: 50

In article <678@alias.UUCP>, rhardock@alias.UUCP (Ron Hardock) writes:
> I am interested in trying out some desktop video on 
> either an Amiga, or an Atari TT (or an Atari ATW).
...
> Secondly, it would also be nice if such a system could
> mix two video signals (from two VCR's) into one.
> The computer could perhaps control how the mixing is done.

I think in general you are going to find this one is hard, assuming you mean
mixing the signals as opposed to grabbing a frame.  The outputs of the two VCRs
need to be synchronized before they can be combined the same way the Amiga has
to be synchronized with an external video signal before its output can be
combined with it (e.g. Genlock).  The customary way to do this with two VCR
signals is with TBCs (Time Base Correctors) which still tend to be expensive
devices.  The lower cost ones I have used also tend to require relatively
expensive VCRs that include the capability to accept an advanced sync signal
that is feed back from the TBC.

Logically it would seem that you should be able to get away with one TBC to
sync one VCR with another one that was free running but generally you find that
in practice both VCRs have to be equipped with TBCs.  This setup is often
referred to as "A B Roll" in editing systems.

> I am also unsure of what computer platform to choose.
> Beside the Amiga, other choices I can see are:
> - Atari STE/TT 	(provides a color palette of 4096),
> - Atari ATW 	(provides 16 million simultaneous colors),
> - Mac II 	(provides 16 million simultaneous colors).

Can't comment on Atari.  I think doing video from a Mac II is going to be
expensive 1) because the Mac with 16 million color capability is itself
expensive when compared to the Amiga, and 2) I believe the output from the Mac
is not at standard NTSC video rates so it is incompatible for video production
work and requires addition equipment to convert to suitable signals.

The Amiga on the other hand was designed from the ground up to produce NTSC
standard video.  It also has a built-in capability to synchronize to an
external signal, thus making genlocks much easier and cheaper to build.  Yes,
there are limits on what the Amiga can do in terms of number of colors and so
on, but nothing can come within a mile of it in terms of *cost effectiveness*
in video production applications, and its price/performance point is at a
*very* useful level of functionality for what a great many of us want to do. 
It is not suitable for broadcast network production, but it costs a few percent
of what the networks do use.

It depends on how much you want to spend.  The Amiga is cheap enough compared
to the alternatives that you can buy it, get your feet wet, and then if you
really want to spend the big bucks later your Amiga investment will only be a
drop in the bucket.  And it will still be useful for a dozen other
applications.