NAIM AV2 Owner's Manual page 20

10.0 av2 operation
Dolby Digital
Dolby Digital is a fully digital decoding technology that provides three full bandwidth
front channels, two full bandwidth surround channels, and one low-frequency effects
channel - a channel scheme known generically as "3/2.1" (or "5.1"). The encoding
technique for Dolby Digital, known as Dolby AC-3, has since 1995 been used on many
Video Laser Discs and more recently on DVD. Dolby AC-3 encoding can also be found on
digital television services. In addition to encoding audio for six channel replay, Dolby AC-
3 incorporates compression techniques that ease audio data storage and transmission
demands and can enable, for example, a single DVD to carry a complete movie.
Dolby Digital 2/0
A variation of Dolby Digital 3/2.1 is Dolby Digital 2/0. Dolby Digital 2/0 takes advantage
of Dolby AC-3 data compression in order to reduce the data storage demands of stereo
programme material. The "2/0" denotes the use of just two main audio channels with no
low frequency effects channel. Programme material encoded for a "2.1" (two main
channels with one sub-woofer channel) channel scheme is also available and can be
handled within Dolby 2/0 decoding.
Dolby Digital Surround EX
The Dolby Digital Surround EX theatre system was co-developed by Dolby Laboratories
and Lucasfilm THX, and was first used theatrically for the movie Star Wars: Episode I:
The Phantom Menace in 1999. The system uses 5.1-channel Dolby Digital encoding but
delivers an additional surround channel by mixing its signal into the left surround and
right surround channels using matrix encoding. This additional channel is matrix
decoded upon playback and routed to one or more centre rear speaker. Listeners with
regular 5.1 channel Dolby Digital systems do not lose the extra surround channel
information; it is simply reproduced by the left surround and right surround channels.
DTS Surround
DTS Surround is an alternative digital audio encoding format that has become popular
with feature film producers and can therefore be found on many DVDs. The first feature
film to be DTS encoded was Jurassic Park in 1993. DTS Surround provides a similar 3/2.1
channel scheme to Dolby Digital with the encoding technology also providing data
compression. The DTS data compression ratio is lower than that in AC-3 however and it
is argued that DTS can provide better audio quality. The downside of any quality
improvement over AC-3 is however higher data storage requirements.
DTS-ES Matrix
DTS-ES (Extended Surround) Matrix is an enhancement of DTS Surround where a seventh
channel is matrix encoded into the left and right surround channels (matrix encoding is
the class of technology used in Dolby Surround Pro Logic). DTS-ES Matrix provides a 6.1
channel scheme with the extra channel used to reproduce effects located directly behind
the listener.
DTS-ES Discrete 6.1
DTS-ES Discrete 6.1 differs from ES Matrix in providing a fully independent seventh
audio channel rather than it being matrix encoded into two existing channels. This
enhancement provides opportunities for producers and engineers to generate surround
effects that would not be otherwise possible.
DTS Neo:6
DTS Neo:6 provides a decoding technique that enables legacy analog or digital stereo
programme material to take advantage of contemporary decoding technology and 6.1
channel schemes. Material matrix encoded for four surround channels, or even un-
encoded stereo material can be processed by the DTS Neo:6 decoder to generate 3 main
channels, 3 surround channels. The low-frequency channel is generated by down-stream
filtering.
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