A way of producing sound for motion pictures where the sound is recorded directly onto the film in the camera at the time of shooting. Sound and picture are thus on a single strip of film from the start, with image and sound in projection sync with each other. Used primarily for news and sports where the relatively limited-fidelity of single system cameras can be tolerated. Cheaper than double-system sound, but also less flexible. Video is, by definition, single-system sound, but may be used as a double-system if a separate audio recorder is used during filming.