NotTaR of Television Sets : What is the deal with Macrovision copy p..  
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What is the deal with Macrovision copy protection?

(From: Jeroen H. Stessen (Jeroen.Stessen@philips.com).)

JVC owns the patent for VHS. JVC has made a deal with Macrovision that from a certain date in the past NO VHS recorder licenced by JVC shall be able to record any video signal that contains Macrovision's copy protection pulses. Any video recorder from before that date (VHS or other) might well work OK on the altered video signal ! The copy protection pulses upset the video-AGC and H-sync. TV's usually don't have a video-AGC. The stabilizer box removes the extra pulses and makes it into a normal video signal again. No VCR should ever know the difference, so they should all record properly again.

At the same time, all TV's are required to ignore the copy protection pulses. As a TV-designer I can tell you that this is sometimes far from trivial. Not in the least because in the beginning we were not included in "the deal". There may be TV's around whose brightness and/or sync will be disturbed by the Macrovision pulses. Officially, this is the reason for existance of the stabilizer boxes: to view better, not to copy better. Unofficially, they are sold for copying, of course.

The next step will be that digital-TV decoders will output an analog TV signal with Macrovision copy-protection pulses so that you may watch but not record your pay-per-view program. Same problem, same solution ...

And I thought that PAL/Secam/NTSC were *standards*, sigh ...

Whether they like it or not (and from personal experience I can tell you that we don't like it) it is the responsibility of the TV set-maker (in your case Sony) to build a TV that takes the Macrovision copy protection pulses without showing any side effects on the screen. Seems like they didn't do a good job on your TV :-). But they will have to fix this, your complaint is valid. I think in this case it may be the dealer's responsibility too, maybe you can trade it for a different brand ? And do try it out first ...

Sadly, more complex TV's seem to suffer more than the simpler, old-fashioned, designs. Unfortunately, Macrovision seems to be satisfied when their pulses do not affect the majority of (mostly older) TV's. In your Sony TV, the clamping circuit seems to be affected by some ultra-black pulses in the signal. Maybe an anti-Macrovision decoder can help you, officially they are designed for THIS purpose.

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