Patent ID: 7423561

Claim:
A modulation method for symbols in a frame of a compact disc, comprising the steps of: receiving a plurality of data words; modulating each data word into a code word of a corresponding data symbol; providing a plurality of combinations of potential merge bits to be inserted between successive symbols of the frame; generating at least one combination of candidate merge bits according to the plurality of combinations of potential merge bits, a data symbol immediately preceding the location of the candidate merge bits, and a data symbol immediately succeeding the location of the candidate merge bits, wherein each combination of candidate merge bits satisfies a predetermined run length restriction on bits contained in the frame; and when a group of possible combinations of candidate merge bits is detected: calculating a cumulative digital sum value (DSV) for each combination of candidate merge bits; selecting the combination of candidate merge bits which minimizes (optimizes) the absolute cumulative DSV when a subsequent group of possible combinations of candidate merge bits is detected or after a predetermined delay; and inserting the selected combination of candidate merge bits between the two successive data symbols.