Technical Information Of SDDS


SDDS channel arrangement with 5 front channels, 2 surround channels and a subwoofer channel or "5/2.1".
Original format used: 8 micrometre square data bits. Final format used: 24 micrometre square data bits.

The format carries up to 8 channels of discrete digital sound encoded using Sony's ATRAC codec with a compression ratio of about 5:1 and a sampling rate of 44.1 kHz. The channels are:
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 obviously more than the maximum 1.536 megabits per second DTS format bitrate, and far greater than the cinema Dolby Digital bitrate of 0.37 megabits per second.
For additional data security the two sides of the film are separated by 17 frames - so a single splice or series of missing frames will not result in a total loss of data.