Abstract: A method and apparatus for recording and reading information in the form of a track of pit and land areas on an optical digital disc record carrier. The information is first encoded from symbol blocks of data bits into symbol blocks of channel bits to which are added merging bits selected so as to minimize the d.c. unbalance or digital sum value of the channel bits. Those parts of the stream of channel bits for which the d.c. unbalance does not meet predetermined criteria are subjected to selective scrambling to correct such unbalance prior to recording. During read-out the correctively scrambled parts of the recovered symbol blocks of data bits are descrambled in an inverse manner. Information identifying such parts is recorded with the channel bits. The invention also relates to a record carrier on which information has been so recorded.