METHOD AND DEVICE FOR EXTENDING AUDIO-VIDEO SERVICES WITH HIDDEN CHARACTERS AND LINKED DATA Russian patent published in 2003 - IPC

FIELD: cable television, direct satellite broadcasting, or internet systems. SUBSTANCE: audio and video material is protected against unwanted copying by means of combination of hidden characters embedded into active part of audio or video signal incorporating additional copying protection data [capability (cryptographic counter) or second hidden character] using 21 lines of vertical blanking interval sweep for NTSC system. On user s desire to pay for record video signal incorporating hidden character and capability is transferred to recording device for comparison with aid of capability hashing function, and recording is enabled in case of their coincidence. Second hidden character check is made as follows: reproducing device yields no-capability audio or video signal and disables further copying. One copy is enabled to be made upon payment. EFFECT: provision for controlled copying of audio or video signal in above-mentioned signal transfer systems. 36 cl, 12 dwg