Sony Dynamic Digital Sound

Sony Dynamic Digital Sound ( SDDS) is a multi -channel sound system for digitally encoding and playback of the audio from movies.

Design and function

SDDS has a maximum of eight different channels, five of them in the front, two on the sides and an LFE ( Low Frequency Effects, subwoofer ) for special low-frequency sound effects below 120 Hz All SDDS processors are flexible in the number of channels and can be of four to eight channels in different variants install universal. The SDDS - processor takes over the distribution of non-existing channels on the speakers you have (in practice, this is usually the downsampling of 8 -channel movies on an existing 5.1 system ).

First use

SDDS was first used on June 17, 1993, four movie theaters in Los Angeles and New York with the film Last Action Hero. The first German SDDS film was " Wolf". Since it could not copy lab in the early days SDDS in Germany, the few German SDDS copies were imported from the USA. The rest of the German copies had only a Dolby SR sound track. Many of the former SDDS copies a short SDDS sound trailer was directly vorkopiert. However, this meant that this was also in cinemas with sound systems without SDDS, since no attention was paid after the first performance on which cinema got a copy with SDDS Sound ( SDDS copies have next to the SDDS sound also the standard Dolby SR optical sound and are therefore compatible with all analog cinema sound systems ). Later it came from it and gave it to them equipped with SDDS cinema decoders to stick a SDDS trailers before the film to make the audience to the SDDS sound alert.

Encoding

The sound data stored in the SDDS in two optical tracks left and right outside the film perforation and read by a special reader with two CCD cameras. For the compression and encoding the proprietary ATRAC method ( Adaptive Transform Acoustic Coding) is employed. For all processors, whether first generation ( DFP - D2000 ) or second generation (DFP -D3000, D2500 DFP ) are used ATRAC 2 decoder ICs. Among the eight audio channels come further four backup channels. On each side of a film four main and two backup channels are stored (see error correction).

SDDS is the sound format in the cinema, which - among other things due to the 8 4 channels - currently the highest data rate before DTS and Dolby Digital has (as of 04 /2006).

SDDS can indeed be retrofitted on all standard 35mm projectors, but the reproduction of films with SDDS soundtrack is comparatively complicated, because the fine structures of the SDDS soundtracks require great care: Copies should theoretically be drawn with more than half the playback speed, normal was (and is ), however, been many times over.

SDDS is like the competition Dolby Digital and DTS now available in almost all recent Hollywood films. SDDS is relatively uncommon built- in cinema, since the system can play its essential advantage of the five front channels, only on very large canvases, as in only a few theaters from approximately 600 seats are usually available in big cities. Many movies also have only a 5.1 SDDS film sound or automatically blended from the other front channels sound for the two additional front channels. Investing in a third system in addition to Dolby Digital and DTS, therefore, not worth it for most cinema operators.

Error correction

Another special feature of SDDS is the error correction. Apart from the normal, usual even with Dolby Digital methods of error correction for dust and scratches on the film copy the SDDS, the " DCM " (digital concealment mode) - a digital backup. The system stores a total of twelve full-fledged audio channels, but it is irrelevant whether it is the subwoofer, a normal or a backup channel. The data are distributed on the two tracks of the 35- mm film copy as follows:

On the side of the analog soundtrack ("S - Side" - Sound -Side):

  • Subwoofer ( SW)
  • Center right ( RC)
  • Right (R )
  • Surround Right (SR )
  • Backup center (C ')
  • Backup left ( Lmix )

On the image side ( "P -side " - Picture -Side):

  • Center (C )
  • Center left ( LC)
  • Left (L )
  • Surround Left (SL )
  • Backup subwoofer ( SW ' )
  • Backup right ( Rmix )

Both tracks are copied puts on the film of 17.8 and pictures are synchronized by delays in SDDS processor to the image. This makes it very unlikely that the mating damaged data simultaneously and thus are unreadable (a typical damage could a splice in the film copy be ). Should the SDDS processor not be able to correct the corrupted data using the normal error correction, it accesses the data the opposite side back ( not located by the 17.8 - pictures - offset at the damaged film location ). From center and subwoofer exist direct copies as backup, the remaining channels are - separately for the right and left - mixed together ( Lmix is a mix of left, center left, surround left). Due to this fact, it may happen that when on the standard in surround sound track a helicopter flies, on the other channels but silence reigns, can be heard on all channels of the damaged side of the helicopter. To prevent this, each sound track info for the decoder stored as must be played on the respective channels in a backup case, according to the mix. The helicopter is therefore continue to listen to all channels of a page, but only in the surround in the actual volume. Dialogue in the center and deep bass information in the subwoofer remain completely unaffected. So ( two movie images at 24 frames per second for the duration of a splice, ) fallback to a backup track in most cases remains the short inaudible.

If a long piece of film as 17.8 images be damaged such that neither conventional error correction, nor the digital backup methods help, remains - in the case of a film copy with all audio formats - a throwback to DTS and Dolby Digital and only if none of the three digital systems running error-free, a throwback to the analog optical soundtrack (usually Dolby SR ).

Alternatives

  • Digital Theater Systems (DTS )
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