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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.
Windows Media
®
Audio 9 Professional
Windows Media
®
Audio 9 Professional (WMA9 Pro) is a
discrete surround format developed by Microsoft
Corporation.
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