The technologies in brief - Dolby Digital
Article from Dolby Laboratories Inc.
Dolby Labs. Dolby Labs.
Click NEXT to read FAQ about Dolby Digital
Article from Dolby Laboratories Inc.
Click to read Frequently Asked Questions about Dolby Digital
Dolby Digital, sometimes known as "AC-3" for the technology on which it is based, is a perceptual coding for consumer applications that enables storing and transmitting from one to 5.1 audio channels at a low data rate. Dolby Digital audio is used for digital television, digital cable, and DBS transmissions, and for DVD and laser discs.
The Dolby Digital 5.1-channel format
    A unique feature called "downmixing" makes it possible for any consumer playback system with Dolby Digital decoding, regardless of channel configuration, to play 5.1-channel Dolby Digital programs. Mono and two-channel consumer decoders automatically create mono, stereo, or Dolby Surround Lt/Rt mixes "on the fly" from multichannel programs. As a result, the same multichannel Dolby Digital bitstream can be delivered to, and satisfy, all listeners. (See: Dolby Digital Downmixing) 
     Supplementary information known as metadata is added during production, post-production, or transmission to identify a Dolby Digital soundtrack's production format—mono, stereo, matrixed or discrete surround—and ensure proper playback. Other metadata parameters include dialnorm, which maintains a constant dialogue-keyed playback level for all program material and sources, and dynrange, which applies a pre-determined amount of dynamic range compression when listening conditions warrant, such as late at night.
Dolby Digital Downmixing
(For more details on "Surround Sound Technologies" click on any image)
Click to Return to Home Page