Macrovision

Macrovision is an analog copy protection forvideo. The method uses an interference signal to prevent video stored on DVD from being dubbed onto VCRs.

In Macrovision, an interfering signal is keyed into the video signal, causing the automatic brightness control to malfunction during video editing. The analog noise signal is not part of the DVD data, but is generated by DVD players and satellite receivers in response to a command in the data stream.

Similar techniques are based on the interference signal being keyed into blanking intervals to prevent synchronization.