 Over the course of 1930–31, the only major players using sound-on-disc, Warner Bros. and First National, changed over to sound-on-film recording.Vitaphone's dominating presence in sound-equipped theaters, however, meant that for years to come all of the Hollywood studios pressed and distributed sound-on-disc versions of their films alongside the sound-on-film prints.Fox Movietone soon followed Vitaphone into disuse as a recording and reproduction method, leaving two major American systems