Sketch Of 7.1 Extended Surround By SDDS(Sony Dynamic Digital Sound)



  • 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(Adaptive Transform Acoustic Coding) 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 reliability 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.
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