Fremgangsmåde til kopibeskyttelse af en optagelsesbærer med et mönster af logiske fejl

摘要

A method for copy protecting a record carrier (1) is disclosed, in which method the copy protected record carriers (1) are provided with a pattern of logical errors (2) which cannot be corrected by the error correcting rules predefined for said record carrier (1) and which pattern of logical errors (2) is defined by error locations and non-error locations. The pattern of logical errors (2) represents access control information. The logical errors (2) are generated during decoding the bit sequence read from the record carrier (1). Bit errors may be positioned in the bit sequence so as to counteract de-interleaving which is part of an error decoding process in a reading device and accumulate in error words which are uncorrectable.