Method and apparatus for modifying a video signal to inhibit unauthorized videotape recording and subsequent reproduction thereof

摘要

A standard video signal is modified such that the modified video can be displayed in a normal fashion on a standard monitor device, yet copies made of the modified video signal by videotape recorders will reproduce a video signal containing disturbances which cause a generally unviewable display on a standard television or other video monitor device. The video signal is converted from a standard frame rate to a predetermined, non-standard frame rate video signal utilizing a videotape recorder modified to record at a non-standard speed. A burst interfering signal also can be added. A method of permitting a normal picture to be displayed from the modified video signal includes adding delay devices to a VCR or video monitor to respond to the non-standard frame rate and filtering or replacing the burst interfering signal.