Motion Picture Sound - part 3

Motion Picture Sound - part 3

Digital Film Sound Formats

introduced 1988 introduced 1991 introduced 1993 introduced 1993
by Sonic Associates by Dolby Laboratories by Digital Theater Systems by Sony Electronics

1990 - Dick Tracy released June 15 as the first 35mm feature film distributed with a digital soundtrack by Cinema Digital Sound (CDS), developed by Eastman Kodak and Optical Radiation Corp. "The system was set up in the typical Left, Center, Right, Right Surround, Left Surround, LFE channel format. CDS encoded 16-bit PCM audio in a compression process called Delta Modulation. The process is very similar to normal PCM coding, but with one major difference. PCM coding records the intensity of every sample to a zero db level. That requires 16-bits for each sample. Delta Modulation records the intensity differences of successive samples, and that doesn't require nearly as much data. The compression level of CDS ran approximately 4:1." (quote from Bobby Henderson, CDS) However, the system replaced the optical analog soundtrack without allowing any backup track for theaters not equipped with the $20,000 digital playback system. Also, theaters preferred to wait for the Dolby digital system that was compatible with an analog track.

from Dolby Labs
1991 - Dolby Stereo Digital (SR-D), with compatible Dolby SR 35mm prints providing both digital and analog optical soundtracks, announced at ShoWest in Las Vegas in February as the first application of Dolby AC-3 multi-channel digital audio coding; the SR-D digital sound film format added 6 digital optical tracks, recorded between sprocket holes, to the 4 existing Dolby SR analog optical tracks on the edges of the film strip - SR-D has a compression ratio of 10:1, a dynamic range 120db, a frequency response of 20-20,000Hz, and a 16-bit data rate of 384 kb.

1992 - Batman Returns premiered June 19 in 10 theatres equipped with new Dolby DA10 Digital Film Sound Processor

1993 - Jurassic Park released May 30 as the first film with DTS sound, developed by Terry Beard, founder of Digital Theater Systems in Westalke Village, CA, partly owned by Steven Speilberg and Universal Pictures. This digital sound film format records 6 tracks on separate CD-ROM disks, synchronized by an optical timecode track recorded on the film, co-existing with a backup optical soundtrack similar to Dolby Stereo.

from the unofficial DTS Page
DTS has a compression ratio of 4:1, a dynamic range of 96db and a frequency response of 20-20,000Hz; DTS Coherent Acoustic Coding is flexible and can combine lossy compression (data beyond normal hearing range is removed) with lossless compression (data is sampled and restored), capable of a 24-bit linear PCM data rate, although most common is a 20-bit data rate that is higher quality than the 16-bit rate used in compact discs, and at 240 kb/s per discrete channel or 1040 kb for all six channels, it is faster than the 384 kb used by Dolby AC-3. Theaters are allowed different installations, some known as DTS-6 or as a lesser quality 4-channel DTS-S (see comments of Dan Sharnhorst at "Digital Sound." Bill Neighbors, current president of DTS, claims DTS is installed in 10,000 theaters world-wide with annual sales of $20 million. DTS films include Braveheart (1995, Oscar winner for Best Picture), Apollo 13 (1995, Oscar winner for Best Sound), Twister (1996), Independence Day (1996), the Star Wars Trilogy 1997 re-release, Batman and Robin (1997), Con Air (1997)

1993 - Last Action Hero released July 18 using the Sony Dynamic Digital Sound (SDDS) digital sound film format that put 6 or 8 tracks of digital sound on 2 optical stripes on each edge of the film strip, recorded on the cyan layer beneath the other emulsion layers, using the lossy ATRAC algorithm of the Sony Minidisc technology with a compression ratio of 5:1, dynamic range of 105db and a frequency response from 5-20,000Hz. It is compatible with a backup standard optical soundtrack such as Dolby SR.

from the unofficial SDDS Page

1996 - DTS trailer film for Jurassic Park: The Lost World released: "The teaser trailer, which debuted on December 13 at forty locations in the United States and two in Toronto, Canada, is driven by a modified DTS that activated six stategically placed strobe lights employed to comlement the images that appear on the screen. Using DTS technology, the timing for the strobe lights is encoded into the trailer's print, which is synched to the highly reliable DTS CD-ROM system. Audiences viewing the teaser trailer feel as if they are caught in a rainstorm complete with life-like sound and lightning provided by the strobe lights." (press release from DTS).

1996 - The English Patient was the first Oscar-winning American film with a digitally edited soundtrack, winning Walter Murch two Academy Awards for film and sound editing.

1998 - Dolby became the leading producer of motion picture sound processors used in theaters worldwide with over 50,000 sold; projector attachments such as the CP500 digital cinema processor introduced in 1995 were capable of decoding 2 of the 4 soundtracks recorded on most film prints (see chart at right from Audio).

chart from "The Magic of Film Sound" in Audio 1999/05
1998 - Lost in Space premiered April 3 as the first major American film with an all-digitally produced soundtrack.

1998 - The Last Broadcast premiered Oct. 19 as "the first desktop feature film" produced and exhibited digitally, co-sponsored by Texas Instruments using its DLP digital cinema projector.

1999 - Star Wars: Episode I - The Phantom Menace was released May 19 in the U.S. with Dolby Digital Surround EX providing an added rear center audio channel. On June 18, it was the first major studio motion picture to be exhibited in digital cinema in 4 theaters with digital projectors by Texas Instruments and by CineComm.

2000 - Jan. 1 Disney released Fantasia/2000 in the IMAX film format with 6-channel digital sound.

1910-1929 - see Motion Picture Sound part 1
1930-1989 - see Motion Picture Sound part 2


- 1999-2000 by Steven E. Schoenherr. All rights reserved.

Recording Technology History Notes | this page revised 12/7/00
AES - Audio Engineering Society