convert VHS to DVD

[Mike McCarty]

Tim wrote:
> 
> Patrick Doyle:
> 
>>I once read that, while MacroVision held the patents on their
>>particular mode of copy protection for video tapes, they also held the
>>patents on all of the obvious ways to circumvent the copy protection.
> 
> 
> Impossible bit of wishful thinking on someone's behalf (like all
> fanciful ideas about making it "impossible" to copy something).
> Replacing syncs on a video signal is a standard practice in television
> studios, when a signal passes through some video equipment.  The idea's
> as stupid is trying to outlaw drinking rainwater instead of paying for
> the city supply...

Actually, usually to remove MacroVision, one needs to *remove* the
"extra" sync pulses it puts in. :-)

> In a TV studio, we'd call such a device a "proc amp" (video processing
> amplifier).  Apart from allowing us to replace syncs, we can adjust
> various video signal levels at the same time.
> 
> 
> 
>>I just assumed that there were no consumer "de-macrovision" boxes
>>available, since anybody who built one would be (presumably) sued by
>>MacroVision for patent infringement.
> 
> You won't get a purpose-built "de-macro" box, not because of a patent
> reason, but because of anti-piracy laws about circumventing such things.

Ah, but "Video Clarifiers" and "Video Stabilizers" are quite legal.
Many TVs don't deal well with the AGC fiddling done by MacroVision,
anymore than do tape recorders.

> But since there's other devices that'll do the required task (replace
> bastardised syncs with normal ones), you can use one of them.  There's
> nothing illegitimate about replacing the syncs on a video signal,
> there's many reasons why one might need to do that, none of them have
> anything to do with piracy.

Yeppers. There is a simple circuit which needs a couple of pots adjusted
which kills most versions of MacroVision pretty handily. I haven't
built it, but I've looked over the circuit, and it should work.

http://www.hobby-electronics.info/projects/MacrovisionKiller.html

> Search around for a video stabiliser, or stabilizer, sync re-inserter,
> or other device names as have been provided in this thread.  If you
> order something from overseas, check that it can work with your local
> video standard (60Hz NTSC if you're in America).  You may find such
> things advertised as being able to fix up Macrovision, though many have
> been threatened by Macrovision for advertising the claim, so they don't
> specifically mention that, anymore.

They also have disclaimers on them, like "This device is not for making
illegitimate copies of copyright material." Some even claim that they
"can't" be so used.

[snip]

Mike
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