Reading data from optically readable data storage media

摘要

Data is read from an optically readable data storage medium (1) arranged to carry primary data (4) and security data (6). A beam of radiation is directed toward a data storage surface (3) of the optically readable data storage medium (1) and reflected signals are converted into electrical signals, the signals being processed to ascertain the presence of primary data (4) carried by the optically readable data storage medium (1) and security data (6) carried by the medium. Typically an output (such as video or audio) is permitted to output the primary data only upon detection of appropriate security data (6).