Abstract: A method and system for overriding error correction capabilities of digital optical media is provided. The overriding of the error correction codes (ECC) is accomplished by causing a non-correctable pattern of erroneous symbols to occur in the ECC codeword. Specific redundancy symbols are replaced with invalid symbols. The non-correctable error pattern is recognized by the ECC decoder as being non-correctable and the ECC decoder does not attempt to change the values of any symbols of an ECC codeword that is contaminated by the detectable non-correctable error pattern.

Abstract: A method of authenticating a Compact Disc, to distinguish an original Compact Disc from an unauthorized copy thereof. One or more invalid symbols are written into the subcode of the original Compact Disc, such one affecting the Q-channel, by using special equipment. The Q-channel normally contains only track location information whose format and content are precisely defined by the applicable standards, and thus ordinary consumer Compact Disc recording equipment does not receive external Q-channel input, but rather generates Q-channel data internally when recording. Therefore, invalid symbols affecting the Q-channel of an original Compact Disc cannot be copied by ordinary consumer Compact Disc recording equipment. Consequently, the presence of data in the Q-channel of a Compact Disc serves to distinguish an original Compact Disc from an unauthorized copy thereof.

Abstract: A method for authenticating a digital optical medium to determine if it is original or an unauthorized copy. One or more special bistable data subunits are written onto the original digital optical medium by recording bistable data symbols and other intentional errors into the data subunit such that the data subunit will be on the error-correction limit threshold. A bistable data symbol is a data symbol for which a player will randomly read at least two different values. Depending on which values are read for the bistable data symbols, the bistable data subunit will either be error-free and readable (at or below the error-correction limit) or will be erroneous or unreadable (above the error-correction limit). When an unauthorized copy of the digital optical medium is made, the data subunit with the address of the bistable data subunit on the original digital optical medium will be a monostable data subunit with constant data, because special hardware equipment is needed to record bistable data symbols.