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From: berggren@eecs.cs.pdx.edu (Eric Berggren)
Newsgroups: sci.electronics
Subject: Re: VCR copy protection
Message-ID: <746@pdxgate.UUCP>
Date: 24 Nov 90 10:25:28 GMT
References: <1923@mts.ucs.UAlberta.CA>
Sender: news@pdxgate.UUCP
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userDANC@mts.ucs.UAlberta.CA (unknown) writes:

>Is anyone aware if a scheme exists to 'copy protect' commercial
>VHS tapes?  In running a recent tape through a second video recorder,
>it looked as if the signal had become scrambled, though viewing it on
>a normal television worked fine.  As a second year Electrical Engineering
>student, I would be very curious in learning the details of the protection
>scheme.  (looks like I have a bit of catching up to do).
>Dan

  There are several companies using a "copy protection" scheme called...
(damn! can't even remember the name). An easy way to tell if it is present
is to set the V-Hold so that you can see the v-trace header at the top of
the screen. If the tape has this scheme, you will see several flashing
white boxes. Unfortunately, this "invisible" protection, wreaks havok on
more sophisticated and sensitive VCR equipment images. However, Radio
Electronics published an article couple years back called the "Macro
Scrubber". This simple little box will remove this protection.
(It is only for the purpose of improving the quality of the image and
 not for copying video cassettes. <right>! )
  This is the only scheme that I know of. There are probably other, less
popular ones. I haven't looked too deeply though. The box has seemed to
do the job.


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