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Surround sound formats
Below is a brief description of the main surround sound
formats you’ll find on DVDs, satellite, cable and
terrestrial broadcasts, and video cassettes.
Dolby
The Dolby technologies are explained below. See
www.dolby.com for more detailed information.
Dolby Digital
Dolby Digital is a multichannel digital audio coding
system widely used in cinemas, and in the home for DVD
and digital broadcast soundtracks. It can deliver up to six
discrete audio channels, comprising five full range
channels and a special LFE (low frequency effects)
channel used mainly for deep, rumbling sound effects;
hence the term “5.1-channel” Dolby Digital.
In addition to the format features above, Dolby Digital
decoders offer downmixing for compatibility with mono,
stereo and Dolby Pro Logic audio from a number of bit
rates and channels. Another feature, called Dialog
Normalization, attenuates programs based on the
average level of dialog in a program relative to its peak
level (also known as Dialnorm) in order to achieve
uniform playback level.
Dolby Digital Surround EX
Dolby Digital Surround EX (the EX stands for EXtended)
is an extension of Dolby Digital encoding whereby a
surround back channel is matrixed into the surround left/
right channels for 6.1 channel playback. This allows for
compatibility with Dolby Digital 5.1 channel decoding, as
well as for decoding using Dolby Digital EX.
Dolby Pro Logic IIx and Dolby Surround
Dolby Pro Logic IIx is an improved version of the Dolby
Pro Logic II (and Dolby Pro Logic)
decoding
system. Using
the innovative “steering logic” circuit, this system
extracts surround sound from sources as follows:
•
Dolby Pro Logic
– 4.1 channel sound (mono
surround) from any stereo source
•
Dolby Pro Logic II
– 5.1 channel sound (stereo
surround) from any stereo source
•
Dolby Pro Logic IIx
– 6.1 or 7.1 channel sound
(stereo surround and surround back) from two
channel or 5.1(and 6.1) channel sources
With two channel sources, the “.1” subwoofer channel is
generated by bass management in the receiver.
Dolby Surround is an
encoding
system which embeds
surround sound information within a stereo soundtrack,
which a Dolby Pro Logic decoder can then use for
enhanced surround listening with greater sound detail.
Manufactured under license from Dolby Laboratories.
“Dolby”, “Pro Logic”, “Surround EX” and the double-D
symbol are trademarks of Dolby Laboratories.
DTS
The DTS technologies are explained below. See
www.dtstech.com for more detailed information.
DTS Digital Surround
DTS Digital Surround is a 5.1-channel audio coding
system from Digital Theater Systems Inc. now widely
used for DVD-Video, DVD-Audio, 5.1 music discs, digital
broadcasts, and video games. It can deliver up to six
discrete audio channels, comprising five full range
channels, including an LFE channel. Higher sound
quality is achieved through the use of a low compression
rate, and high rates of transmittance during playback.
DTS-ES
DTS-ES (the ES stands for Extended Surround) is a
decoder that is capable of decoding both DTS-ES
Discrete 6.1 and DTS-ES Matrix 6.1 encoded sources.
DTS-ES Discrete 6.1 gives ‘true’ 6.1 channel sound, with
a completely separate (discrete) surround back channel.
DTS-ES Matrix 6.1 has a surround back channel matrixed
into the surround left/right channels. Both sources are
also compatible with a conventional DTS 5.1 channel
decoder.
DTS Neo:6
DTS Neo:6 can generate 6.1 channel surround sound
from any matrixed stereo source (such as video or TV)
and from 5.1 channel sources. It uses both the channel
information already encoded into the source, as well as
its own processing to determine channel localization
(with two channel sources, the “.1” subwoofer channel is
generated by bass management in the receiver). Two
modes (Cinema and Music) are available using DTS
Neo:6 with two channel sources.
DTS 96/24
DTS 96/24 is an extension of the original DTS Digital
Surround which offers high quality 96 kHz / 24-bit audio
using a DTS 96/24 decoder. This format is also fully
backward compatible with all existing decoders. This
means that DVD players can play this software using a
conventional DTS 5.1 channel decoder.
“DTS”, “DTS-ES”, “Neo:6” and “DTS 96/24” are trademarks
of Digital Theater Systems, Inc.
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