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Ishaam
Macrovision Help
on May 24, 2004 at 2:10:59 pm

Hi All,


I am trying to copy a legal seminar vhs tape that I own. The copied
tape displays greenish colors and also the movie hops (lines coming into the picture and so forth). I believe that what I am experiencing is some type of copy guard protection.

What I would like to know is this, if I use the product GO-DVD by the video guys, if that would be able to assist me with my problem that I am having to remove the copy protection.

Thanks
Ishaam


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toniok
Re: Macrovision Help
on Jun 8, 2004 at 1:21:34 am

Well, you hit on a topic that I've been researching. I can share what I've learned, but I haven't found an ideal solution yet.

There are two kinds of Macrovision. Macrovision Level 1 deals specifically with the so called pseudo-sync pulses. These are horizontal-sync like pulses that are inserted on 8 lines of video at the beginning of the video field. They pulsate on and off in a cyclic fashion. These pulses confuse the AGC circuitry of VCR's in a way that it makes reacts by trying to adjust the brightness level of the signal. Since the AGC of a VCR reacts much slower than the one of a TV set, you see the brightness changing at the output of a VCR but the TV, with the same pulses coming in, adjust so much quicker, that you don't see any change in the picture.

Level 2 is called Colorstripe. It consists of changing the Phase of the color burst signal which is present immediately after every horizontal sync pulse. The phase changes in the middle of the burst every certain number of lines, not in every line. The VCR reacts to these by again, getting "confused" into changing the colors on the particular line the burst change is in. The result is a band of lines across the picture about an inch apart or so. You don't see the effect on the output of the VCR, only the recorded signal when playing back.

One way to fix this is using a Time Base Corrector. TBCs are stabilizers which restore sync completely by regenerating both the horizontal sync pulses and the color burst for every line. This results in a clean signal which the VCR was designed to have, to record properly. Regeneration of the color reference burst is not normal on most "enhancers" or "stabilizers" - they simply clamp certain lines in the vertical blanking period to black level. Regenerating the color reference burst is a little trickier. Almost all stand alone TBCs do regenerate the CB.

So the trick is to find an inexpensive TBC that regenerates the color burst. As far as I can tell, no such animal exists. There are ones around $300, but no manufacturer will discuss this application due to legal ramifications.

There are other devices out there, such as NTSC/PAL converters, that also have TBCs built in and may work. Or may not. There are even various enhancer/stabilizers that supposedly do work. Altogether I've come up with more than 20 devices, but I don't have the time or money to buy and test them all.

Can anyone can add any hands-on experience to this?

TonioK


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dailyrushes
Re: Macrovision Help
on Feb 21, 2005 at 7:13:04 am

Have you tried Shrinkwrap?


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toniok
Re: Macrovision Help
on Feb 21, 2005 at 10:06:38 pm

I have since had a friend confirm that the Sima GoDVD does in fact get rid of Macrovision 1 & 2 AND also CGMS. This leaves a lot of options open..


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