Copy protection method and apparatus

摘要

A copy protection method and apparatus is disclosed. Various protection signals are added to a video signal in the vicinity of the color burst part of the signal. The protection signals are selected to interfere with the frequency down conversion process in the video recorder so that the color burst cannot be recorded properly. The protection signals are chosen so that when a modified video signal containing the original video signal and the protection signals has been recorded by a video recorder, playback of the modified video signal exhibits visual artefacts that are not visible before recording of the modified signal occurred. The protection signals are also used to carry digital control information for controlling the operation of a digital recorder.