Abstract: Method for determining and cataloguing a digital data file fingerprint. A data file, such as an audio file, is converted into digital format. The file is then sampled using at least one reference value. From the occurrences of the samples in the digital data file being equal to the reference value, a fingerprint is determined. This fingerprint is provided to a digital data file fingerprint database, along with proprietary and other related information. Users may then quickly ascertain the proprietary information from a data file through accessing the database with a fingerprint. Furthermore, users may detect whether or not a data file has been manipulated, such as compressed using modern compression technology, by comparing a fingerprint of the suspect data file with an original fingerprint found in the database.

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.

Abstract: An optical disc having a plurality of user data written to the disc from a lead-in zone to a lead-out zone, the disc comprising a plurality of control display data composed of a plurality of subcode registers, each having a value, where the control display data are written to the disc interposed with the user data and written to the lead-out zone and hidden data encoded within one of the subcode registers in the lead-out zone. The p-bit register in the lead-out zone of the optical disc required to toggle at a rate of 2 Hz. In one second, the optical disc reader reads 75 p-bit registers, therefore a perfect 2 Hz toggling cannot be achieved. The location of a p-bit state composed of a fewer number of p-bit sector is used to represent a bit value of hidden data.

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: 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.

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.