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US 2006/0136729 A1Published application
Copy protection for optical discs
AssigneeMacrovision Europe Limited
InventorWilliam Christopher Doyle
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AssigneeMacrovision Europe Limited
InventorWilliam Christopher Doyle
Estimating the term…
Optical discs, such as CDs, have been protected by the use of an authenticating signature which cannot be copied to another disc. A playing device is required to identify the existence of the authenticating signature in order to access the content of the disc. The authenticating signature may comprise bad sectors at known locations. CD writers now available to consumers allow error detection and error correction data to be specified and this has led to circumvention techniques designed to simulate an original disc. During the writing of a copy disc, bad sectors are identified and provided with alternative data together with incorrect error detection and error correction data. When the copy disc is played bad sectors are reported in exactly the same locations as reported by the original disc thereby enabling the disc to be played even though it is a copy. To defeat techniques which use the error detection and error correction data to circumvent the copy protection, it is proposed to store authenticating signatures in sectors in Mode 2 format. Sectors formatted in this way are not subject to error detection and correction.
A copy protected optical disc carrying an authentication signature, the authentication signature being arranged so that it cannot be accurately copied by a writer of recordable discs, and wherein the authenticating signature is located on the optical disc in such a manner which identifies that there is no error detection nor error correction data associated therewith.
A copy protected optical disc carrying a sequence of bits representing the data stored on the disc, the sequence of bits being arranged in sectors, the optical disc having an authentication signature in at least one sector, the authentication signature having been produced by altering selected bits to provide a pattern of erroneous bits which cannot be corrected during playback, and wherein the authenticating signature is located on the optical disc in a manner which identifies that there is no error detection nor error correction data associated therewith.
A copy protected optical disc carrying data arranged in sectors and having an authenticating signature in at least one sector, wherein the authenticating signature is made up of data patterns chosen to cause DSV problems for writers of recordable discs, and wherein the authenticating signature is located on the optical disc in a manner which identifies that there is no error detection nor error correction data associated therewith.
A method of copy protecting optical discs, the method comprising adding an authenticating signature to an optical disc during its mastering process, the authenticating signature being arranged so that it cannot be accurately copied by a writer for recordable discs, and the method further comprising locating the authenticating signature on the optical disc in a manner which identifies that there is no error detection nor error correction data associated therewith.
A content file for use in manufacturing a copy protected optical disc carrying an authentication signature, the authentication signature being arranged so that it cannot be accurately copied by a writer of recordable discs, the content file comprising data to be stored on the optical disc, the data being arranged in sectors and being provided with appropriate error detection and error correction data, and the data including the authentication signature which is arranged in at least one sector, the or each sector containing the authentication signature being formatted in a manner which identifies that there is no error detection nor error correction data associated with the authenticating signature.
Dependencies are inferred from the claim text.