Optical disc mastering technique includes use of secondary track embedded between turns of primary track to prevent copying

摘要

The optical disc includes two sets of spiral tracks - a primary track and a secondary track. The secondary track is embedded between the turns of the primary track, with a consistent offset. Filling zones and a specific offset are set up in order to enable normal reading of the disc, but to prevent copying. The copy protected disc includes a protective zone in which a secondary spiral (PB) is embedded between the turns of a main spiral (PA). The pitch separating each spiral from an adjacent turn maintains a standard value. To enable un-disturbed playback with standard reproducing devices, an offset of k sectors is provided between the sectors of a common address (n) on each of the two spirals. Additionally there are filling zones (FAcc, FDec) at the beginning and at the end of the useful portion of the secondary track (PB) to avoid the risks of gaps or collapse between the tracks.