Sony Dynamic Digital Sound
Abbreviation | SDDS |
---|---|
Formation | 1993 |
Type | Cinema sound |
Location |
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Owner | Sony |
Website | www.sdds.com |
Sony Dynamic Digital Sound (
History
Although originally slated to premiere with 1991's Hook, the SDDS project was delayed and instead premiered on June 17, 1993, with Last Action Hero. Since then, over 2000 movies have been mixed in Sony Dynamic Digital Sound, and as early as 1999 over 6,750 movie theaters were equipped with SDDS.
The code name for the SDDS project was "Green Lantern", taken from the name of the comic book hero and the old term of "magic lantern" used to describe the original projected pictures in the late 19th century. Green came to mind because the key to imprinting the 8 micrometre data bits was to use a green laser.
Initial development efforts were conducted for Sony's Columbia Pictures Sound Department under contract with Semetex Corp. of Torrance, California. At Semetex, the SDDS Chief Architect was Jaye Waas and the Chief Optical Engineer was Mark Waring.
The Semetex prototype design actually had the eight channels of uncompressed data placed into three locations: data bordering both sides of the analog sound track and additional data tracks bordering the opposite edge of the picture frame. These locations were chosen to ensure the data were not placed into the sprocket perforation area of the film to prevent the known wear and degradation that occurs in the perforation area (due to the mechanical film sprockets) from degrading the data. Clocking and guide tracks were placed on each side of the film near the sprockets. The prototype sound camera imprinted the Digital audio and Analog audio 'at speed'. A companion digital reader was designed to form a complete system. After Sony received the prototype they enlarged the data bits from the original 8 micron (micrometer) size and moved the data locations; the eight digital audio channels are now recorded on (and recovered from) the edges of the film. As Sony engineers became more actively involved in the project, the design of the SDDS format evolved toward a more robust implementation, including the use of 5:1
The SDDS development at Semetex took just 11 months from concept to working sound camera.
When it came time for deployment, since Sony also owned the Sony Theaters chain (later sold to
SDDS was consistently the least popular of the three competing digital sound formats, the other two being
SDDS's much-touted eight track playback capability never quite caught on, as it required that a separate eight channel sound mix be created in addition to the six channel mix that is needed for SRD and DTS, an additional expense for the studios. Out of the 1,400 plus films mixed in SDDS, only 97 of them to date have been mixed to support the full 8 channels, most of them Sony (Via Sony Pictures/Columbia/Tristar) releases. Because of the added installation expense, the majority of SDDS installations are 6 channel (5.1) installations, as opposed to 8 channel (7.1) installations.
- See also List of 8 channel SDDS films.
While most major studios eventually began putting SDDS tracks on their releases, most independent films only came with Dolby Digital tracks, leaving many SDDS-equipped, or DTS theaters playing analog sound in otherwise state-of-the-art auditoriums. A few titles released under the Kidtoon Films program used SDDS tracks. As Dolby Digital (and to a lesser degree, DTS) began to emerge as the clear winner in the digital sound battle, Sony Cinema Products quit manufacturing SDDS encoders and decoders, although it will continue supporting equipment that is still deployed in the field.
Out of the three competing formats, SDDS was the only format not to have a corresponding home-theater version, and Sony ceased production of new units in the early 2000s.
Technical
- Original format used: 8 micron (micrometre) square data bits, 16 bit per audio channel, 8 audio channels, 2 clock tracks, 2 guide tracks for alignment with the film.
- Final format used: 24 micrometre square data bits.
The format carries up to 8 channels of Dynamic Digital Sound (DDS) encoded using Sony's
- 5 screen channels
- Left
- Left center
- Center
- Right center
- Right
- 2 surround channels
- Left surround
- Right surround
- Subwoofer channel
Additionally there are 4 backup channels encoded – in case of damage to one side of the film or the other. These are:
- Center
- Subwoofer
- Left + left center
- Right + right center
This gives a total of 12 channels, for which the total bitrate of 2.2 megabits per second. This is more than the maximum 1.536 megabits per second
For additional data reliability the two sides of the film are separated by 17 frames and half, so a single splice or series of missing frames will not result in a total loss of data.
Reader
The SDDS reader is mounted on top of a 35mm
Decoder
The SDDS decoder is installed in the sound equipment rack. The decoder receives the information from the reader and translates it into