RCA Photophone
Videos
RCA Photophone was the trade name given to one of four major competing technologies that emerged in the American film industry in the late 1920s for synchronizing electrically recorded audio to a moti
Magazine ad insert introducing RCA Photophone, 1928
Optical sound
Videos
Optical sound is a means of storing sound recordings on transparent film. Originally developed for military purposes, the technology first saw widespread use in the 1920s as a sound-on-film format for
Edge of a 35-mm film print showing four types of soundtrack. The stereo optical sound strip is located on the right, with waveforms for left and right channels. To the far left is the SDDS digital track (blue area to the left of the sprocket holes), then the Dolby Digital (grey area between the sprocket holes labeled with the Dolby "Double-D" logo in the middle), and to the right of the analog optical sound is the DTS time code (the dashed line to the far right.)
A transparent program disc imprinted with concentric optical sound tracks, used for the Optigan musical organ
Example of a variable-area sound track on the right side of the frames on this strip of 16mm film. The width of the white area is proportional to the amplitude of the audio signal at each instant.
Newspaper ad for a 1925 presentation of De Forest Phonofilms shorts, touting their technological distinction: no phonograph.