Abstract: A motion picture film projector includes a sound head for playing back or for recording a sound track on the film. Absolute synchronism between the picture and sound is assured by the use of a single motor and common shaft to move the film past the sound head and to rotate the optical rectification system. In one embodiment, the sound head is mounted on the concave side of a stationary arcuate film guide opposite the sound track, and the film is driven past the sound head by a sprocket wheel mounted on the common shaft adjacent the optical rectification system.