Sony Dynamic Digital Sound (SDDS®) is a theatrical cinema sound system developed by Sony. For this format, digital sound information is recorded on both outer edges of 35mm film release prints (see diagram). Due to this placement, SDDS tracks are more prone to damage than the other digital formats (Dolby’s SR-D and DTS). The failure of any digital track will trigger playback of either another digital format (if available), or (most likely) the analog sound track. This switching of sound tracks is audible to most audiences as a change in volume level and a slight loss of fidelity and low-end, although it is less noticeable in a properly calibrated auditorium.
SDDS supports up to eight independent channels of sound: five front channels, two surround channels, and a sub-bass channel. Until SDDS, only Cinerama™ and Cinemiracle used more than six sound tracks for theatrical presentation. However, of the over 1,400 plus films mixed in SDDS, only around 100 of them have been mixed to support its full eight-channel capability. Most cinemas are capable of only four to six-track stereophonic sound; in these theaters, eight-channel SDDS soundtracks are downmixed to meet their speaker configurations.
The additional equipment required to present eight-channel SDDS in theaters makes it more expensive to install, so it tends to be present only in larger venues. SDDS lagged behind both SR-D and DTS in deployment due to this expense, its late arrival in the market compared to the other digital formats, and reliability issues due to the placement of its tracks on film. It is still supported by most of the major studios, but the equipment is no longer frequently installed in new cinemas, making this essentially a “dead” format. However, it will continue to be supported in optical recording as a courtesy to those theaters that have not yet switched to one of the other digital formats.
SDDS is not currently available on any home entertainment format.
This article is licensed under the GNU Free Documentation License found at http://www.gnu.org/copyleft/fdl.html. It uses material from the Wikipedia article at http://en.wikipedia.org/wiki/Sdds.
The SDDS tracks are highlighted in this illustration in yellow.
A photo of a print featuring all four audio formats (or "quad track")- from left to right, SDDS (blue area to the left of the holes), Dolby Digital (grey area between the sprocket holes), analog sound (the two white lines to the right of the Dolby Digital track), and the DTS timecode (the dashed line to the right of the analog track.)
SDDS channel arrangement with 5 front channels, 2 surround channels and a subwoofer channel or "5/2.1".