smith@umn-cs.UUCP (03/13/85)
I've been collecting graphics examples from TV with my VCR and I'm wondering about what's in store if I try to collect examples from cassette movies as well. In particular I'm wondering about 'copyguarding'. I've heard that it essentially weakens a synch signal so that the image can usually be displayed but can't be accurately recorded. A side-effect seems to be that some TVs can't reliably display copyguarded tapes. Questions: 1. Do all manufacturers routinely copyguard tapes? Is there a degradation in the image of copyguarded tapes even on 'modern' TVs? 2. Is there some way of controlling the effects without buying one of those copyguard defeaters? For example, I have both RF and audio/video output from my deck. Is one or the other less succeptible? Would my tracking control do me any good?
brown@nic_vax.UUCP (03/16/85)
> Questions: > > 1. Do all manufacturers routinely copyguard tapes? Is there a degradation > in the image of copyguarded tapes even on 'modern' TVs? In the case of VHS commercial tapes, no, manufacturers do NOT use copyguard anymore. It turned out not to do any good for two reasons. One, because of the third party boxes that replaced the butchered vertical synce with good vertical sync and two, almost all of the table model, three speed, VHS machines will lock onto any signal that is even remotely close to vertical sync. I have been thru three VHS table top units and they don't even blink at the copyguard. I run a lot of commercial tapes thru my VHS machines and I haven't found a one that uses copyguard anymore. Now, if you have a Beta machine, that is another story. Sony likes to build sync separator circuits that like only good sync. Some of their machines will not record unless the sync is perfect. Copyguard works very good on those units. A anti-copyguard box is needed. But, since I do not have a beta unit, I can only go by what I find out from users of Beta machines. Another good point for VHS. As for the image, it is not touched. All copyguard does is change the characteristics of the vertical sync. > 2. Is there some way of controlling the effects without buying one of those > copyguard defeaters? For example, I have both RF and audio/video output > from my deck. Is one or the other less succeptible? Would my tracking > control do me any good? Like I said above, if you have a fairly recent (a couple of years old), tabletop VHS unit, you shouldn't have to worry about making copies. If you have Beta, you may need one of the copyguard boxes. Whenever you make copies, the direct video connections should always be used. Going via the RF always adds more noise to the signal and degrades the bandwidth a little bit. The RF modulators in video decks are cheap compared to the rest of the unit. I hope this helps you a little bit. If you have anymore questions, just send me some mail via uucp. Mr. Video
smith@umn-cs.UUCP (03/20/85)
I got two or three useful mail replies to my query. The concensus seems to be that hardly anyone uses copyguard, probably because the newer equipment isn't adversely affected by the weakened synch signal that copyguard is based on. One fellow reported that his copyguard defeater actually caused more trouble than it eliminated, since it provided one more electronic stage to muddy the signals. It is also likely that copying excerpts from videotapes is at least as illegal as xeroxing excerpts from copyrighted computer manuals. In both cases the providers don't consider extraction of excerpts to be 'fair use'. "But Inspector Erskine, I didn't mean any harm...."