Patent ID: 7685641

Claim:
A method for producing a copy-protected audio compact disc master containing audio data samples of an audio signal, the method comprising: selecting at least one audio data sample of the audio signal; locating a data symbol representing said at least one audio data sample; overwriting said data symbol with an erroneous symbol; locating a first C1 error-correction codeword associated with said data symbol; producing a first disabled C1 error-correction codeword by altering at least one of a first plurality of C1 P-parity symbols in said first C1 error-correction codeword; locating a C2 error-correction codeword associated with said data symbol; producing a disabled C2 error-correction codeword by altering at least one of a plurality of C2 Q-parity symbols in said C2 error-correction codeword; locating a second C1 error-correction codeword associated with said at least one of a plurality of C2 Q-parity symbols in said C2 error-correction codeword; producing a second disabled C1 error-correction codeword by altering at least one of a second plurality of C1 P-parity symbols in said second C1 error-correction codeword; and recording onto the master said erroneous symbol, said first disabled C1 error-correction codeword, said disabled C2 error-correction codeword, and said second disabled C1 error-correction codeword.