Abstract: Magnetic recording tape has groups of coded marks which successively identify successive portions of the tape. An optical reader is positioned to read the marks on the tape as the tape travels through the sound reproduction system, and a decoder decodes the marks and identifies, in numerical form, the specific portion of the tape which is in position for sound reproduction. The system has the capability of identifying the specific portion of the tape in position for sound reproduction irrespectively of the speed or direction of travel of the tape within the system, or the position of the tape when operation of the system is initiated.