Prevention of disk piracy

Apparatus for protecting data recorded on an original data storage medium against unauthorized copying, comprising an error generator, which receives data encoded in accordance with an applicable recording standard and alters a portion of the encoded data prior to recording of the data on the medium such that the altered data are identified as erroneous according to the standard,

• wherein the data recorded on the medium include ancillary data, which are used by a processor in an intended application of the medium to operate upon the altered portion of the data, and
• wherein the ancillary data comprise error detection codes, and wherein the error generator alters a data value in the encoded data without changing a corresponding error detection code, such that the value is identified as erroneous using the corresponding code, and
• wherein in the intended application using the original medium, the alteration of the portion of the data is concealed by interpolation based on the corresponding error detection code.

Apparatus for protecting data recorded on an original data storage medium against unauthorized copying, comprising an error generator, which receives data encoded in accordance with an applicable recording standard and alters a portion of the encoded data prior to recording of the data on the medium such that the altered data are identified as erroneous according to the standard,

• wherein the data recorded on the medium include ancillary data, which are used by a processor in an intended application of the medium to operate upon the altered portion of the data, and
• wherein the ancillary data comprise error detection codes, and wherein the error generator alters a data value in the encoded data without changing a corresponding error detection code, such that the value is identified as erroneous using the corresponding code, and
• wherein the error generator changes the value of a digital audio signal, such that when the ancillary data are not used to operate upon the altered portion, the quality of an audio output signal generated responsive to the data is noticeably degraded.

A data storage medium that is resistant to unauthorized copying, on which medium data encoded in accordance with an applicable recording standard are stored, a portion of which encoded data is altered such that the altered data are identified as erroneous according to the standard, the stored data including ancillary data which are used by a processor in an intended application of the medium to operate upon the altered portion of the data,

• wherein the ancillary data comprise error detection codes, and wherein altering the portion of the data comprises changing a data value without changing a corresponding error detection code, such that the value is identified as erroneous using the corresponding code, and
• wherein in accordance with the standard, the error detection code is recalculated upon copying of the data, so that the altered portion is no longer identified as erroneous, and
• wherein in the intended application using the original medium, the alteration of the portion of the data is concealed by interpolation based on the corresponding error detection code.

A data storage medium that is resistant to unauthorized copying, on which medium data encoded in accordance with an applicable recording standard are stored, a portion of which encoded data is altered such that the altered data are identified as erroneous according to the standard, the stored data including ancillary data which are used by a processor in an intended application of the medium to operate upon the altered portion of the data,

• wherein the ancillary data comprise error detection codes, and wherein altering the portion of the data comprises changing a data value without changing a corresponding error detection code, such that the value is identified as erroneous using the corresponding code, and
• wherein changing the data value comprises changing the value of a digital audio signal, such that when the ancillary data are not used to operate upon the altered portion, the quality of an audio output signal generated responsive to the data is noticeably degraded.