TW245796B - Copy protection for hybrid digital video tape recording - Google Patents

Abstract

A hybrid digital/analog video recorder prevents both analog and digital copying. The recorder (including a digital tape deck) inputs and outputs both analog and digital video signals. At the analog input, a detector detects conventional copy protection in the analog input video, and in response disables recording thereof. At the digital input, a first detector detects anti-copy bits present in the input material and in response prevents recording. A second bit detector detects serial copy prevention scheme bits, and in response adds an anti-copy bit to the input digital stream, preventing later copying of such material. When another bit detector detects anti-copy bits present in the playback digital data stream prior to conversion to analog, an analog copy protection signal modifies the output analog signal, inhibiting copying of the output signal. In another version, a specially adapted video recorder or playback device copy protects video source material which for technical reasons is not copy protectable. A copy protect "flag" is provided in a predetermined location in the video signal to be protected. The video recorder or playback device, upon detection of the flag at playback, modifies the output standard (NTSC) video signal with aconventional copy protection process.