Abstract: Apparatus and method for recording data to an optical disc to prevent unauthorized duplication of the disc. The disc includes a data placement zone to which first data are written at a first data rate as the disc is rotated at a selected linear velocity. The disc further includes a velocity disruption zone to which second data are written at a second different data rate as the disc is rotated at the selected linear velocity. The variation in frequency between the first and second data rates preferably causes a readback system to lose frequency lock on the second data during a continuous access operation on the first and second data. An unauthorized disc can also be detected by comparing the disc linear velocity as the second data are accessed to a target linear velocity. Access to the disc can be denied when a velocity mismatch is detected.

Abstract: An apparatus and method are disclosed for optimizing the writing of data to an optical disc to improve readback characteristics and minimize the effects of errors. An optimization circuit generates an optimized modulation signal which is used to modulate a writing beam of a laser beam recorder, the optimized modulation signal comprising a series of data symbols that correspond to resulting pits and lands on the optical disc. The optimization circuit optimizes the locations of pit and land transitions on the optical disc by individually adjusting leading and trailing edges of the data symbols, as well as amplitudes of the data symbols. In this manner, the particular length of each pit and land on the disc can be individually selected based on nominal symbol length, as well as other factors including radial and angular locations of the pits and lands on the disc.

Abstract: Method and apparatus for preventing unauthorized replication of a digital data file. A plurality of second data set samples are substituted for a plurality of user data samples in a user data sequence to generate a combined data set. Error correction codes are calculated to correct errors in the combined data set. Uncorrectable errors are then intentionally written to the error correction codes corresponding to the second data set samples so that, during playback, the readback system conceals the corresponding second data set samples. An unauthorized copy of the digital data file will not include the uncorrectable errors; thus, the same readback system will output both the user data samples and the second data set samples, with the second data set samples interfering with the integrity of the user data samples.

Abstract: An optical disc in which hidden data are stored for forensic tracking or copy protection purposes. This disc includes a contiguous user data portion comprising a set of user data samples which, when accessed by a readback system, generates a human detectable output. The disc further includes a null zone adjacent the contiguous user data portion comprising a sequence of user data fields storing a set of user data samples which, when accessed by a readback system, generates an output with a specified signal to noise ratio so as to be substantially undetectable by a human, wherein hidden data are written to at least selected ones of the user data fields of the null zone to convey a specified informational message related to the optical disc, the specified informational message undetectable by a human when the null zone is accessed by the readback system.