Macrovision?

[lancerx]

What is that? i just read the Glossary but i didnt understand it well, i want to buy a macrovision for my vhs but and not sure whats that for, i want to encode my pal videos to ntsc, i don{t know if that aparat would let my ntsc vhs read my pal videos.

thanks

[Solarjetman]

Macrovision is not a physical thing you buy. It is copy protection built into a VHS or DVD (the video, not the physical disk). Usually what happens when you try and copy a macrovision protected tape is the video will alternate between very dark and very light throughout the movie. However, if you just play the video on a TV, the alternating brightness will not occur.

EDIT: I found this well written description of how it works off the internet...

Here is a simple explanation of how the method works. It exploits the automatic gain control (AGC) circuit in the recorder. The purpose of the AGC is to adjust the level of the video signal in such a way that the recording capabilities of the tape are fully used. This means that weak signals are amplified and strong ones are attenuated.

In the Macrovision method, some new signals are inserted in the non-visible portion of the picture. These signals can make the VCR think that a perfectly normal picture is suddenly way, way too bright. The AGC circuit therefore darkens it until it thinks the brightness is normal. Of course, now the REAL picture is very dark. The picture is varied between bright and dark periodically in order to defeat simple eliminators that would just amplify the dark and murky signal back to almost normal.

In fact, there was an early version of the method which had a static level of brightness, but it was easy to readjust the AGC gain setting inside the VCR. The level shifting was obviously added fairly soon after that discovery.

Why isn't the TV affected? Well, most TV sets do not have any AGC-circuits at all, and the rest behave differently from VHS ones.

[lancerx]

Thank you solarjetman!!

it happens that i just saw a macrovision remover and i thought that it was for let you use pal videos on ntsc vhs.