Path: utzoo!mnetor!intacc!mann
From: mann@intacc.uucp (Jeff Mann)
Newsgroups: comp.multimedia
Subject: Re: Video Toaster and TBC question
Message-ID: <1991Jun10.213907.15813@intacc.uucp>
Date: 10 Jun 91 21:39:07 GMT
References: <1991Jun4.172727.1889@gpu.utcs.utoronto.ca> <1991Jun6.030507.8211@rick.doc.ca> <22202@cbmvax.commodore.com>
Distribution: na
Organization: Inter/Access Artists' Centre Toronto
Lines: 46

In article <22202@cbmvax.commodore.com> chrisl@cbmvax.commodore.com (Christian Ludwig - CATS) writes:
>(Andrew Patrick) writes:
>>
>>If I am not mistaken, a tape deck requires the feature of an "external
>>sync in" in order to work with a TBC.  Most of your home tape
>>recorders, and the cheap ones at the video stores, do not have this
>>feature.  Some of the newest models of high-end decks have built-in
>>TBC's, but they are expensive.

Sorry, you are mistaken. If the TBC has "infinite window" correction,
(you can tell this by whether the TBC can do a freeze frame), then a
sync input on the VCR is not necessary, and any video source (in fact
any signal at all) can be fed into the TBC and made into a clean signal.

>If you want to do Toaster transitions between two tape sources or 1 tape
>and a camera, you really only need 1 player that has a SYNC IN.  You
>would sync this player to the time-base corrected output of the player
>without the SYNC IN connector.

This is wrong too. First of all, there are two types of "being in sync".
The first is genlock. When two video signals are genlocked, both the
horizontal and vertical sync are perfectly in phase. This allows you to
mix (dissolve) or wipe the two pictures together. In order for two VCR
pictures to be genlocked together, a TBC is required for each. (Well, ok,
you *can* actually cause the TBC to genlock to the non-TBC'ed picture,
but this is a very silly thing to do, as it defeats the stabilizing
function of the TBC.)

The second type of "being in sync" is called switchlock (although you
rarely hear that term).  This means that the vertical sync signals are
in phase, but the horizontal is not.  You can cut (switch) between the
pictures, but not combine (dissolve, wipe, etc.) them.  This is the type
of sync provided by using the SYNC IN connector on the VCR. This feature
is used for sync'ing VCR's in a cuts-only editing system, and also by
some TBC's that don't have full-frame correction and need to get the
signal "close" (in switchlock) before they can work.

The toaster requires TBC's on ALL VCR signals, even if you only have
one VCR. I think there are now some TBC's-on-a-card available quite
cheap for the Amiga.

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