Sony Dynamic Digital Sound
SDDS stands for Sony Dynamic Digital Sound, which is a cinema sound system developed by Sony. Digital sound information is recorded on both outer edges of the 35mm film release print. 7 main channels (5 screen + 2 surround) plus a sub-bass channel are available, usually only 3 of the available 5 screen channels are used as most cinemas do not have the extra speakers installed. The digital track includes 4 fall-back tracks for occasions when the full signal is unrecoverable due to dirt or damage on the film.
History
SDDS was first launched with the Arnold Schwarzenegger film Last Action Hero on June 17, 1993.
This format made use of 8 channels of discrete digital sound, using 5 screen speakers as opposed to three, including an extra set of left and right speakers.
Since then over 1,300 movies have been mixed in Sony Dynamic Digital Sound, and as of early 1999 over 6,750 movie theaters have been equipped with SDDS.
Competitors
SDDS's competitors include the popular Dolby Digital format which premiered with the 1992 film Batman Returns.
Another competitor of SDDS is DTS, (Digital Theater Systems) which premiered with Steven Spielberg's blockbuster hit Jurassic Park in 1993, just a few weeks before SDDS premiered with Last Action Hero.
Technical specifications
SDDS is printed on both edges of the film, just outside the sproket holes and uses four back-up tracks, in case the reader fails or if the film is scratched or has dirt in it.
SDDS also has a compression ratio of 5:1.
Rumors
Rumors have been circulating on the Internet that Sony might be planning on releasing SDDS as an optional soundtrack on their new Blu-Ray format and quite possibly the competing HD-DVD format (although that is even less likely).
With the larger amount of space that these new formats can carry, having an optional SDDS track is possible.
These speculations, however, are mostly unfounded and there is yet no official word from Sony that they are planning to release SDDS into the home theater market.
The Full 8-Channels
Movies in SDDS may be mixed to support six channels of sound (5.1), or all 8 channels (actually 7.1, since the sub-bass channel is really counted as ".1").
Out of the 1,300 plus films mixed in SDDS, only 95 of them to date have been mixed to support the full 8 channels. Mostly because most sound mixers prefer mixing in the popular 5.1 format and because SDDS is far too expensive to install and maintain for most theater owners.
Theaters that are installed to support 8 channel movies will still end up with two wasted channels because of the small number of 8 channel SDDS movies (only about 3 to 5 are released a year).