A method of recording an audio signal in the emulsion of a film alongside, and in sync with, the picture frames. See DES. The photographically printed film soundtrack that appears either between one row of perforations and the picture in an answer or release print (in 35mm), or along the edge of the print opposite that with the perforations (in 16mm). The track area on a 35mm print takes up a total width of 100 mils, which, being one-tenth of the space between the sprocket holes, displaces the centerline of the image on the film by 50 mils, hence called the Academy centerline.
(2) The master or original photographic soundtrack sound track made directly from the mono mix or 35mm three-track mix. This strip of film has no video image, but is printed along with A- and B-rolls onto the composite answer print or release print. The track can be a negative or positive image, depending on the type of camera and print stock. See also stereo optical print, 50% level.