OT/Old Recordings/Shameless Plug

From: Geoff Roberts <geoffrob_at_stmarks.pp.catholic.edu.au>
Date: Wed Sep 4 18:20:01 2002

----- Original Message -----
From: "chris" <mythtech_at_mac.com>
To: "Classic Computer" <cctalk_at_classiccmp.org>
Sent: Thursday, September 05, 2002 7:05 AM
Subject: Re: OT/Old Recordings/Shameless Plug


<SNIP>

> It also claims to bypass macrovision when duping VHS or DVD, but I admit,
> I have not tried to copy a macrovised item yet

Pretty much any copy protection system for video can be defeated by putting
a
time base corrector in the analogue signal path between the source and
whatever you are recording it on.
When I worked in television and helical scan Umatic (3/4") stuff started to
appear, we had to
feed it through a TBC to make it presentable for on air. This also sorts out
any form of copy protection, since the
signal has to be playable on a common or garden tv set, not a lot you can do
to it without rendering it unwatchable without special hardware.
TBC's used to cost a packet, (the one we had was worth around $20kAU at late
70's prices and was the size of a big desktop pc.) now they are a single
chip and any half decent camcorder has a much better one. Some systems can
also be defeated by looping the signal through an old beta machine, then
feeding it to your vhs box. (The beta I have neatly regenerates the syncs,
getting around the commonly employed sync amplitude variation protection
system by replacing them with normal .3v sync pulses.) You can recognise
this method by the slow cyclic variation in picture brightness in a copied
tape. You can get external TBC's for a few hundred bucks these days. Note
that they work on the analogue video signal, direct digital to digital is an
entirely different can of worms.

<SNIP>

Geoff in Oz
Received on Wed Sep 04 2002 - 18:20:01 BST