| 摘要 |
PROBLEM TO BE SOLVED: To preclude illegal copying to a digital information signal. SOLUTION: Code word strings 1d', 1f' which are combination of code words C by strictly observing predetermined run-length limitation rules, where, a code word C of q bits is obtained by converting an input data word D of p bits, and error correction codes 1e' and 1g' are subjected to NRZI conversion, and the modulation signals of 1-frame units thereby obtained are connected by a plurality of frames to constitute copying prevention data 13'. When the copying prevention data 13' and a digital information signal subjected to p-q modulation are recorded on a recording medium 10, the error correction codes 1e', 1g' of the copying prevention data 13' are preset to the same values as those of the error correction codes 1e, 1g of copying time added when the reproducing signal of the copying prevention data 13' is copied on another recording medium, and the code word strings of the copying prevention data are coded to be error-corrected by the error correction codes preset to the same values as those of the error correction codes of the copying time. COPYRIGHT: (C)2004,JPO |
