Optical disc authentication using alternate data modulation encoding schemes

摘要

Apparatus and method for writing data to an optical disc, and for subsequently reading the data therefrom. A first modulation encoding scheme (MES1) is defined to encode input data as data symbols having nominal symbol lengths over a first range. A second modulation encoding scheme (MES2) different from the MES1 is further defined to encode input data as data symbols having nominal symbol lengths over a second range. Each symbol length of the second range appears in the first range. The MES1 is used to encode primary data written to the disc while the MES2 is used to encode secondary data inserted at selected locations for disc authentication purposes. A readback system includes a primary decoder which decodes and outputs the primary data, and a secondary decoder which searches for a leading synchronization pattern which, when detected, allows remaining portions of the secondary data to be decoded.