This delay can be adjusted in steps of the time between perforations, (approximately 10.4 ms).Īs of 2015, Dolby Digital in film sound mixing is being gradually replaced with Dolby Surround 7.1, with the more advanced Dolby Atmos technology also gaining in popularity. If a penthouse soundhead is used, the data must be delayed in the processor for the required amount of time, around 2 seconds. To allow for the dual-soundhead arrangement the data is recorded 26 frames ahead of the picture. However, for new projectors it made sense to use dual analogue/digital soundheads in the normal optical soundhead position under the projector head. The simplest way of converting existing projectors is to add a so-called penthouse digital soundhead above the projector head. Almost all current release cinema prints are of this type and may also include SDDS data and a timecode track to synchronize CD-ROMs carrying DTS soundtracks.Ī Dolby Digital Penthouse Soundhead mounted on a mid-1950s vintage Kalee model 20 projector File:35mm film audio macro.jpgĪ photo of a 35 mm film print featuring all four audio formats (or quad track)- from left to right: Sony Dynamic Digital Sound (SDDS) (blue area to the left of the sprocket holes), Dolby Digital (grey area between the sprocket holes labelled with the Dolby Double-D logo in the middle), analog optical sound (the two white lines to the right of the sprocket holes), and the DTS time code (the dashed line to the far right.) The analogue soundtrack provides a fall-back option in case of damage to the data area or failure of the digital decoding it also provides compatibility with projectors not equipped with digital soundheads. All film prints with Dolby Digital data also have Dolby Stereo analogue soundtracks using Dolby SR noise reduction and such prints are known as Dolby SR-D prints. The data is then decoded into a 5.1 channel audio source. A charge-coupled device (CCD) scanner in the image projector picks up a scanned video image of this area, and a processor correlates the image area and extracts the digital data as an AC-3 bitstream. A constant bit rate of 320 kbit/s is used. Dolby Digital cinema soundtracks are optically recorded on a 35 mm release print using sequential data blocks placed between every perforation hole on the sound track side of the film. Please see the relevant discussion on the talk page.īatman Returns was the first film to use Dolby Digital technology when it premiered in theaters in the summer of 1992. You can help the The JH Movie Collection's Official Wiki Wiki by citing appropriate references. This section seems 14 be biased or has no references. 5 Dolby technologies in packaged media formats.
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