35 Mm Film - Recent Innovations in Sound

Recent Innovations in Sound

New digital soundtracks introduced since the 1990s include Dolby Digital, which is stored between the perforations on the sound side; SDDS, stored in two redundant strips along the outside edges (beyond the perforations); and DTS, in which sound data is stored on separate compact discs synchronized by a timecode track stored on the film just to the right of the analog soundtrack and left of the frame. Because these soundtrack systems appear on different parts of the film, one movie can contain all of them, allowing broad distribution without regard for the sound system installed at individual theatres.

The analogue optical track technology has also changed: in the early years of the 21st century distributors changed to using cyan dye optical soundtracks instead of applicated tracks, which use environmentally unfriendly chemicals to retain a silver (black-and-white) soundtrack. Because traditional incandescent exciter lamps produce copious amounts of infra-red light, and cyan tracks do not absorb infra-red light, this change has required theaters to replace the incandescent exciter lamp with a complementary colored red LED or laser. These LED or laser exciters are backwards-compatible with older tracks. The film Anything Else (2003) was the first to be released with only cyan tracks.

To facilitate this changeover, intermediate prints known as "high magenta" prints were distributed. These prints used a silver plus dye soundtrack that were printed into the magenta dye layer. The advantage gained was an optical soundtrack, with low levels of sibilant (cross-modulation) distortion, on both types of sound heads.