Patent ID: 7352302

Claim:
An apparatus for allocating codewords of source words to be recorded on a recording medium, the apparatus comprising: a receiver to receive codewords of source words to be recorded on the recording medium; and a controller arranged to allocate, when a preceding codeword “b” and a following codeword “c” form a code stream “Y”, one of two selectable codewords “b 1 ” and “b 2 ” as the codeword “b”, in which the codewords “b 1 ” and “b 2 ” have opposite INVs which are parameters indicating whether the number of ‘1s’ contained in a codeword is an odd number or an even number, and to allocate, when the code stream of “b 1 ” and “c” is “Y 1 ”, and the code stream of “b 2 ” and “c” is “Y 2 ”, codewords such that INVs of “Y 1 ” and “Y 2 ” are maintained to be opposite when the codeword or “b 1 ”, “b 2 ” or “c” should be replaced by another codeword in compliance with a predetermined boundary condition between the codewords.