Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!samsung!think.com!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!news.funet.fi!tukki.jyu.fi!jyu.fi!otto From: otto@tukki.jyu.fi (Otto J. Makela) Newsgroups: sci.electronics Subject: Re: VCR copy protection Message-ID: Date: 23 Nov 90 12:53:08 GMT References: <1923@mts.ucs.UAlberta.CA> Sender: news@tukki.jyu.fi (News articles) Organization: Turing Police, Criminal AI section Lines: 26 In-Reply-To: userDANC@mts.ucs.UAlberta.CA's message of 14 Nov 90 03:34:42 GMT In article <1923@mts.ucs.UAlberta.CA> 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). Yes, there are copy protection schemes for VHS tapes (both NTSC and PAL). And they are used. Basically, what they do is mess up the recorded signal in a way that the 2nd (recording) VCR won't like, but which won't affect TV viewing. The solution is to take the composite or RGB signal that's coming out of the 1st VCR and break it down to RGB + proper syncs and wipe everything else off the signal, then combine everything up again. One cheapo solution is to record in RF, but the quality stinks. These were discussed in quite a lot of detail in Elektor (and they had plans for a copy-protection remover), the issue number evades me at the moment. -- /* * * Otto J. Makela * * * * * * * * * * * * * * * * * * */ /* Phone: +358 41 613 847, BBS: +358 41 211 562 (CCITT, Bell 24/12/300) */ /* Mail: Kauppakatu 1 B 18, SF-40100 Jyvaskyla, Finland, EUROPE */ /* * * Computers Rule 01001111 01001011 * * * * * * * * * * * * * * * * */