Sound film
The primary steps in the commercialization of sound cinema were taken in the mid- to late 1920s. At first, the sound films which included synchronized dialogue, known as "talking pictures", or "talkies", were exclusively shorts. The earliest feature-length movies with recorded sound included only music and effects. The first feature film originally presented as a talkie was "The Jazz Singer", released in October 1927. A major hit, it was made with Vitaphone, which was at the time the leading brand of sound-on-disc technology. Sound-on-film, however, would soon become the standard for talking pictures.
Sound film
The development of commercial sound cinema had proceeded in fits and starts before "The Jazz Singer", and the film's success did not change things overnight. Not until May 1928 did the group of four big studios (PDC had dropped out of the alliance), along with United Artists and others, sign with ERPI for conversion of production facilities and theaters for sound film. Initially, all ERPI-wired theaters were made Vitaphone-compatible; most were equipped to project Movietone reels as well. However, even with access to both technologies, most of the Hollywood companies remained slow to produce talking features of their own. No studio besides Warner Bros. released even a part-talking feature until the low-budget-oriented Film Booking Offices of America (FBO) premiered "The Perfect Crime" on June 17, 1928, eight months after "The Jazz Singer". FBO had come under the effective control of a Western Electric competitor, General Electric's RCA division, which was looking to market its new sound-on-film system, Photophone. Unlike Fox-Case's Movietone and De Forest's Phonofilm, which were variable-density systems, Photophone was a variable-area system—a refinement in the way the audio signal was inscribed on film that would ultimately become the standard. (In both sorts of systems, a specially-designed lamp, whose exposure to the film is determined by the audio input, is used to record sound photographically as a series of minuscule lines. In a variable-density process, the lines are of varying darkness; in a variable-area process, the lines are of varying width.) By October, the FBO-RCA alliance would lead to the creation of Hollywood's newest major studio, RKO Pictures.