An inner ring signal and an outer ring signal according to specific patterns formed on the label side of the optical disc are generated. Timing starts when the outer ring signal reveals the end of a positioning pattern and stops to obtain a timing value when the inner ring signal reveals the start of a square wave defining a specified spoke. A starting spoke is defined according to the inner ring signal and the specified spoke. A deviation bit value is calculated according to the timing value and a bit number of a data to be marked on a certain track of the optical disc. The data is rotated according to the deviation bit value, and then marked on the certain track, starting with the starting spoke.