A simple explanation of the Macrovision™ copy protection method; some new signals are inserted in the non-visible portion of the picture (usually the sync track) - which makes the VCR think that a perfectly normal picture is way way too bright. Therefore, the Automatic Gain Control (AGC) circuit within the VCR automatically darkens the picture until it thinks the brightness is normal - now your recorded picture is far too dark! This embedded signal is varied between dark and light periodically in order to beat simple Macrovision™ or copy protection eliminators, copy disablers, stabilizers, etc.
Is the Macrovision™ on VHS Tapes & DVD's the same?
Yes. On both VHS tapes & DVD discs it is an invisible embedded signal inserted usually within the first 25 lines (sync track) of the picture. However, it is the recording device that makes the difference.
What is the difference between copying to a VCR or a DVD Recorder?
The embedded copy protection signal will activate the AGC circuitry inside a VCR making the recording fade from dark to bright, picture rolling etc - but a DVD Recorder has what they call a CGMS Chip in built, this chip actively searches out for embedded copy protection signals. When it finds them, it then releases its own fail-safe mechanism, disables recording mode and provides a message to the user informing them that they are attempting to copy copyright protected material. DVD Copying is illegal.
What is the point of Macrovision™ ?
Macrovision™ was designed to prevent the copying of tapes & DVD's ensuring that everyone bought their own copy from a recognised reseller thus maximising the sales and royalties of the performers & studio's.
