| 摘要 |
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.
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