Macrovision

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Article #7048

#7048

From: Mike
Date: Wed, 02 Sep 1992 04:10

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     Does anyone know how macrovision allows a video tape to be watched on
     a television but not on a vcr?  I recently looked at a copy protected
     videotape and it appeared that there were 4 white bars on the last
     8 or 9 lines in the vertical interval that periodicly (every 15 or 20
     sec) faded in and out.  It looks like it's changing the average level
     of the picture to mess up the vcr.  If that's the case could this be
     fixed with a clamping circuit or some kind of dc restorer circuit?
     If anyone knows the technical details of how the copy protection scheme
     works I would be very interested. 

     Thanks

Technical Details

Message-ID: <1992Sep2.041037.347@u.washington.edu>

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Newsgroups: sci.electronics,rec.video
Path: arc1-ca.pugleaf.net!sparky!uunet!elroy.jpl.nasa.gov!usc!rpi!usenet.coe.montana.edu!news.u.washington.edu!milton.u.washington.edu!bunky
From: bunky@milton.u.washington.edu (Mike)
Subject: Macrovision
Message-ID: <1992Sep2.041037.347@u.washington.edu>
Sender: news@u.washington.edu (USENET News System)
Organization: University of Washington, Seattle
Date: Wed, 2 Sep 1992 04:10:37 GMT
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