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From: jimm@mitsumi.UUCP (Jim Mackraz)
Newsgroups: comp.sys.mac
Subject: Re: Starring Macs (was Re: Addison's MacII)
Message-ID: <508@mitsumi.UUCP>
Date: Wed, 14-Oct-87 17:48:23 EDT
Article-I.D.: mitsumi.508
Posted: Wed Oct 14 17:48:23 1987
Date-Received: Sat, 17-Oct-87 10:43:51 EDT
References: <6469@ut-ngp.UUCP> <4669@oberon.USC.EDU> <452@auscso.UUCP> <2975@husc6.UUCP>
Reply-To: jimm@mitsumi.UUCP (James Mackraz)
Distribution: na
Organization: Mitsumi Technology Inc
Lines: 39

In article <2975@husc6.UUCP> singer@endor.UUCP (Richard Siegel) writes:
>In article <452@auscso.UUCP> mentat@auscso.UUCP (Robert Dorsett) writes:
>>In article <4669@oberon.USC.EDU> humphrey@skat.usc.edu (Steve Humphrey) writes:
>>And now the "value" part of the message: the few pictures I have seen of Macs
>>turned on have been on the news.  They are always in the background, and in-
>>variably FLICKER like mad. 
>
>	If I had to guess, I'd say that the flicker is because of the
>difference in scan rate between the computer screen and the TV (or movie)
>camera. This also shows up occasionally on the evening news, whenever
>they show a shot of a television screen over in Europe (which uses a 50Hz
>cycle rate for their TV sets, in general).
>
>	How to work around it, I don't know.
>		--Rich

Nice guess.  Different scan rates will cause problems, but even with
the same (or similar) scan rates, problems will occur if pieces
of video equipment are not synchronized (a black band will appear on the
monitor in the picture).

Synchonization of video sources/cameras is called genlock.  I don't know
the scan rate of Macs.  Some PC's can benefit from aftermarket genlocks.
The Amiga was designed with Genlock in mind (the computer's internal
clock is synchronized to external video), and with the genlock peripheral
can be used in video scenes.  Genlock synchronization is also needed
when mixing video sources, such as graphic overlays of video, which
is another function of the Amiga Genlock peripheral.

It is said that all computer displays on Max Headroom (except Max, his
ownself) are now generated on Amigas.  I haven't seen much truly wild,
but the simple graphic overlays of videophones and the like are
easy to do with an Amiga and Genlock.

	jimm

-- 
	Jim Mackraz
	Mitsumi Technology, Inc.		408/980-5422
	{amiga,pyramid}!mitsumi!jimm