Dolby Digital and DTS are six-channel (5.1) digital surround sound systems and are the standard soundtracks in major motion pictures on standard DVD, music, and digital television audio (HDTV). They both use the 5.1 speaker format. The format consists of three speakers across the front and two speakers in the rear. The .1 is a sixth channel called Low-Frequency-Effects and is sent to a subwoofer.
A DVD-Video disc can have up to 8 audio tracks or streams of audio data. Each track can be
in different formats:
* Dolby Digital (AC-3): 1 to 5.1 channels
* MPEG-2 audio: 1 to 5.1 or 7.1 channels
* PCM (Pulse Code Modulation): 1 to 8 channels.
Additional optional formats are provided also:
DTS 5.1 for example. These require
external decoders and are not supported by all players.
The ".1" refers to a low-frequency effects (LFE) channel that connects to a
subwoofer. This channel carries an emphasized bass audio signal.
Linear PCM is uncompressed (lossless) digital audio, the same format used
on Audio CDs and most studio masters. It can be sampled at 48 or 96 kHz with 16,
20, or 24 bits/sample. Audio CD is limited to 44.1 kHz at 16 bits. There
can be from 1 to 8 channels. The maximum bit rate is 6.144 Mbps, which
limits sample rates and bit sizes when there are 5 or more channels.
The 96 dB dynamic range of 16 bits or even the 120 dB
range of 20 bits combined with a frequency response of up to 22,000 Hz from
48 kHz sampling is adequate for high-fidelity sound reproduction.
Lossy audio compression: Lossy
is an audio compression method where pieces of data are
intentionally discarded to reduce the size of the data
stream. Depending on the amount of compression, a
lossy-compressed stream can be close enough to the original
in accuracy and quality that the difference is
insignificant. If the compression is higher, the
lossy-compressed stream can sound quite different from the
Lossless audio compression:
Lossless is a compression method where no
pieces of data are discarded and therefore can reproduce
bit-for-bit the originally recorded audio.
Matrixed audio decoding:
Matrixed channel audio is audio that, when properly decoded,
simulates more audio channels than actually exist in the
audio files or streams. For example, decoding two-channel
stereo audio using Dolby Prologic II can deliver five
matrixed channels over your receiver. Generally matrixed
audio is analog, although it can be digital as is the case
of the rear center channels of Dolby Digital EX
Discrete audio decoding:
Discrete channel audio is audio that is
encoded, transmitted, stored and played back as separate
channels. Generally, multi-channel discrete audio is encoded
digitally. An example of this is Dolby Digital 5.1. Discrete
audio decoding is preferred over matrixed audio decoding.
Here are the various surround sound technologies of recent times:
Dolby Prologic (Matrixed
Analog 4.1 Surround): Dolby Prologic is an
analog matrixed surround sound standard created by Dolby
Laboratories in the 1980s. It is 4.1 surround with
Front-left, Front-center, Front-right, Surround-center, and
subwoofer. Dolby Prologic was succeeded by Dolby Prologic II
Dolby Prologic II
Analog 5.1 Surround):
Dolby Prologic II is an analog matrixed
surround sound standard created by Dolby Laboratories in
2000. It is 5.1 surround with Front-left, Front-center,
Front-right, Surround-left, Surround-right, and subwoofer
channels. Prologic II can process both Dolby Prologic and
stereo sound sources and simulate 5.1 surround pretty well.
While the movie industry has clearly standardized on
discrete digital encoding standards such as Dolby Digital
and DTS, the music and video game industries still rely on
Dolby Prologic II as a standard for surround. Dolby Prologic
II has a movie mode, music mode, matrix mode and game mode.
The music mode adds center and surround channels, but does
not change the nature of the left and right channels. The
movie mode is designed to provide a 5.1 experience for
movies that are not digitally encoded. The game mode
supports decoding for video games.
Analog 5.1 Surround):
Like Dolby Prologic II, DTS NEO:6 is an analog
matrixed surround standard that can up-mix stereo content
into a 5.1 or 6.1 surround format.
Dolby Digital (Discrete Digital 5.1
Surround): Dolby Digital is a family of
digital surround encoding technologies from Dolby
Laboratories. It is also known as AC-3 (Adaptive Transform
Coder 3). It's capable of various channel configurations,
however, it is most widely implemented as 5.1 surround. It
includes Front-left, Front-center, Front-right,
Surround-left, Surround-right, and subwoofer channels. Dolby
Digital is a lossy encoding technology limited to 640 kbits
per second, however, the DVD disc format limit it to 448
kbits per second. Since Dolby Digital treats each channel
discretely and is digitally encoded, Dolby Digital requires
a digital decoder to provide the 5.1 audio standard. Most
home theater receivers can decode Dolby Digital, however, to
get the signal from a source such as a DVD player to the
receiver you must use a digital audio connection such as
optical or coax.
DTS (Discrete Digital 5.1 Surround):
DTS (Digital Theater Systems) is a competing
standard to Dolby Digital. It's a discrete digital surround
standard that offers multiple channel surround including
Front-left, Front-center, Front-right, Surround-left,
Surround-right, and subwoofer channels. Similar to Dolby
Digital, it differs in one primary way. It offers lossy
encoding up to 1536 kbits bandwidth on DVDs compared with
Dolby Digital's 448 kbits. Depending on your sound system,
you may notice a broader dynamic range and less hiss. Like
Dolby Digital, DTS requires that your home theater receiver
support decoding DTS and also requires digital audio
connections (optical or coax).
Dolby Digital EX
Digital 6.1 and 7.1 Surround):
Dolby Digital EX is an update to Dolby Digital
which adds a matrixed Rear-center channel to a 5.1 setup.
This can be accomplished through one (6.1) or two speakers
(7.1). In 7.1, however, the two rear speakers operate as a
Digital 6.1 and 7.1 Surround):
DTS-ES is Digital Theater Systems' competitive
technology to Dolby Digital EX. Like Dolby Digital EX,
DTS-ES builds on DTS and adds a center rear channel using
one or two speakers. It differs from Dolby Digital EX in
that the 6th Rear-center channel can be stored discretely in
the source audio, as opposed to matrixed as it is in Dolby
Dolby Digital Plus
Digital 13.1 Surround):
Dolby Digital Plus, also known as E-AC-3, is a
new standard by Dolby Laboratories that provides beyond 8
channels. Current HD-DVD and Blu-ray implementations,
however, limit it to 8 channels. Dolby Digital Plus
increases the lossy encoding up to 6 Mbps. It is the
required surround sound standard for HD-DVD and Blu-ray high
def discs. It's also the future standard for ATSC HDTV
broadcasts. Current digital audio connection standards
(optical and coax) do not have the bandwidth to support
Dolby Digital Plus. HDMI version 1.3 is the only currently
supported connection methods for Dolby Digital Plus.
Surround): TrueHD is a next-generation
lossless surround encoding standard. Supporting up to
24-bit/96 kHZ audio at up to 18 Mbits, it's a mandatory
standard on HD-DVD and is optional on Blu-ray disc. It uses a
HDMI 1.3 connection standard.
Digital Surround, virtually
unlimited channels): DTS-HD is Digital Theater
Systems' answer to Dolby TrueHD. The specification allows
for unlimited channels that can be down-mixed to the number
of channels supported on the home system. The bit-rate is
also flexible in that it can be as low as lossy DTS, or all
the way up to lossless quality. DTS-HD is an optional
standard on HD-DVD and Blu-ray high def discs.
THX: THX is a certification and
standard created by Lucasfilm both for video content and for
audio and video equipment. There are numerous THX
certifications including: THX Ultra and THX Ultra2 (the THX
standards for dedicated home-theater installations in a
3,000 cubic foot room); and THX Select and THX Select2 (the
THX standards for non-dedicated and smaller 2,000 cubic foot
home theaters). There has been much debate about the
validity of THX certification and whether it provides
measurable value in component and home theater design or do
licensing fees just elevate pricing.
Audio / Video Receivers - User Guide
||Mandatory @ 640 Kbit/s
||Mandatory @ 504 Kbit/s
||Mandatory @ 448
||Mandatory @ 1.5 Mbit/s
||Mandatory @ 1.5 Mbit/s
||Optional @ 756 Kbit/s|
||Optional @ 1.7 Mbit/s (note 4)
||Mandatory @ 3.0 Mbit/s
||Optional @ 6.0 Mbit/s
||Optional @ 3.0 Mbit/s
|DTS-HD Master Audio
note 2: All HD DVD players are required to be able to decode Dolby TrueHD to two channels, however all current players handle 5.1 decoding.
note 4: On Blu-ray Disc, a Dolby Digital Plus audio is stored as two separate components: the 'core' Dolby Digital bitstream at 640 Kbit/s (which is independently playable), and the 'extension' bitstream at 1 MBit/s.
How do I connect my player?
The 1st generation players may not have the latest capabilities but some can be upgraded via a firmware update available by internet download. Many of the 2nd generation players include expanded capabilities such as having 7.1 analog outputs, HDMI 1.3 and decoding for the newest audio codecs.
If you have a Blu-ray disc with a Dolby Digital 5.1 audio source and you have a A/V Receiver with Dolby Digital 5.1 decoding and you have 5 loudspeakers plus a subwoofer connected to your A/V Receiver, you can use an optical or coaxial digital audio cable to connect your Blu-ray Player to your A/V Receiver.
However, if you have a set of 5.1 channel direct analog inputs on your receiver, then this is an even better option, as the 5.1 channel analog outputs of the Blu-ray disc player already contain a decoded surround sound signal.
Also, if you have a higher-end Audio/Video receiver that has direct HDMI inputs (that are not just simply pass through connections), your AV receiver would be able to accept the ucompressed digital audio signal from the Blu-ray Disc player, which is even better than using the 5.1 channel analog signal or the digital audio signal input options. Consult your AV Receiver user manual to see if any HDMI inputs are pass-through only, or if the receiver can decode the audio signal properly.
Now, if you have the newer high-res Dolby TrueHD audio source, then you cannot use your optical or digital coaxial cable connection from player to AV Receiver. Why? Because these simply do not have the bandwidth required to carry the newer datastream. So what are your options?
1) Use the multiple RCA analog audio cables from player to AV Receiver if the player can decode the audio.
2) Use a HDMI 1.3 hookup if you have a HDMI 1.3 capable AV Receiver and player.
Hookup Diagram Blu-ray
BLU-RAY Disc Surround Sound Audio
Blu-ray disc movies can contain new surround sound technologies to complement the newer High Definition video. The newer Audio formats are as follows:
* 100 percent
lossless coding technology.
* Up to 18 Mbps
* Supports up to eight full-range
channels of 24-bit/96 kHz audio.*
by High-Definition Multi-Media Interface,
the new single-cable digital connection for
audio and video.
* Supports extensive
metadata including dialog normalization and
dynamic range control.
*Dolby TrueHD can
support more than eight audio channels. HD DVD
and Blu-ray Disc standards currently limit their
maximum number of audio channels to
* Delivers studio-master-quality sound that unlocks the
true high-definition entertainment experience on
* Offers more discrete
channels than ever before for impeccable
* Compatible with the A/V
receivers and home-theaters-in-a-box (HTIBs) of
today and tomorrow.
* Dialog normalization
maintains the same volume level when you change
to other Dolby Digital and Dolby TrueHD
* Dynamic range control (Night
mode) enables you to customize audio playback to
reduce peak volume levels (no loud surprises)
while experiencing all the details in the
soundtrack, enabling late-night viewing of
high-energy surround sound without disturbing
* Selected as the mandatory format
for HD DVD and as an optional format for Blu-ray
* Mulitchannel sound
with discrete channel output.
* Channel and
program extensions can carry multichannel audio
programs of up to 7.1 channels* and support
multiple programs in a single encoded
* Outputs a Dolby Digital
bitstream for playback on existing Dolby Digital
* Supports data rates as high as 6
* Bit rate performance of at least 3
Mbps on HD DVD and up to 1.7 Mbps on Blu-ray
* Accurately reproduces what the
director and producer intended.
mixing and streaming capability in advanced
* Supported by HDMI, the new
single-cable digital connection for
high-definition audio and
* Can deliver 7.1
channels and beyond* of enhanced-quality audio
at up to 6 Mbps.
* Allows multiple languages
to be carried in a single bitstream.
audio professionals new creative power and
* Compatible with the millions of
home entertainment systems equipped with Dolby
* No latency or loss of quality in
the conversion process.
* Maintains high
quality at more efficient broadcast bit rates
(<320 kbps for 5.1-channel audio).
Selected by the Advanced Television Systems
Committee (ATSC) as the standard for future
broadcast applications; named as an option by
the Digital Video Broadcasting (DVB) Project for
satellite and cable TV.
* Selected as the
mandatory audio format for HD DVD and as an
optional audio format for the Blu-ray
*Dolby Digital Plus can support
more than eight audio channels. HD DVD and
Blu-ray Disc standards currently limit their
maximum number of audio channels to
DTS-HD Master Audio
*Bit for Bit Identical to
the Original Master
*Optional for Both
Blu-Ray Disc and HD-DVD
Dolby Digital Plus is basically a
step-up from SACD and DVD-Audio, but
offering up to 7.1 Discrete channels (and the
capability to do more, although BD and HD-DVD
will only currently support a maximum of 7.1
These new soundtracks are certainly better than their DVD
counterparts as Dolby 5.1 is limited to 640kbps
and DTS is limited to 1509 kbps on DVD. Twice
the resolution of DVD at the minimum for audio,
with dramatically better clarity.
HDMI 1.3 allows your next-generation disc
player to pass the Dolby TrueHD, Plus or DTS HD Master
Audio directly to your receiver or preamp, and
be decoded and processed using your preamp or receiver's Digital / Analog Converters. This assumes of course that your hardware is capable of decoding the signals.
What surround standard
you'll use in a home theater environment to listen to music
will depend on whether you are listening to music from CDs and
digital music (MP3s, wav, AAC, etc.), or from DVD-Audio.
Since CDs and digital music generally include only stereo
2-channel audio, you should choose non-discrete surround
encoding standards such as Dolby Prologic II or DTS NEO:6. For
DVD-Audio, you'll generally want to use one of the discrete
digital encoding standards such as Dolby Digital 5.1 or DTS.
For standard DVDs, a huge
majority of the discs support Dolby Digital 5.1 (AC-3). Many DVDs
support DTS and other Dolby Digital variants (Dolby Digital EX
and DTS-ES). Which audio option you choose when playing a DVD
movie depends on your home theater system. You should choose
the standard that sounds the best and optimizes your
For example, if you are setup for 7.1
audio, then choose DTS-ES or Dolby Digital EX. If in doubt,
Dolby Digital 5.1 is a safe choice. Remember, to use a digital
standard you must have the digital optical or coax connections
to your compatible receiver with proper decoding capability.
HDTV Broadcast and Cable
HDTV, both Dolby Digital 5.1 and Dolby Prologic II are
generally supported. However, which format you actually
receive in the broadcast signal is determined by your local
broadcaster and/or cable company.
With certain channels and
networks, even when programming says it's in
Dolby Digital 5.1 it may not reach your system in digital 5.1.
When that happens, setting your audio receiver/amplifier to
Dolby Prologic II will likely provide the best results. Many
receivers will revert to this setting if a Dolby Digital
signal is not available. Keep in mind that just like DVDs, in
order to use a digital standard you must have the digital
optical or coax connections to your receiver from your cable
or satellite set-top box.
High Def DVD Formats and the Future
For HD-DVD, Blu-ray and future ATSC HDTV, the
standard are Dolby Digital Plus, Dolby TrueHD and DTS-HD.
These standards will drive future audio systems. All of these
devices also support today's Dolby Digital 5.1 standard.
In order to enjoy the benefits of any of
these formats you must have:
- A compatible source
Your source devices such as DVD
player, game console, set-top box, etc., must be compatible
with, or at least allow pass-through of the encoded digital
- The right connections
order to pass digital standards such as Dolby Digital from
your source, you must have the right connections between the
device and your receiver - either digital coax or optical.
For the new high bandwidth standards, such as Dolby TrueHD, you must have a
compatible digital audio connection such as HDMI 1.3 or
- A compatible receiver or
In order to decode the content
from the source device, you must have an audio receiver or
audio amplifier that is able to decode the audio standard
For example, if you are watching a DVD with DTS
audio content offered as an option, and your receiver
supports Dolby Digital but doesn't support and decode DTS -
don't choose DTS in the DVD menu system.
- The right speaker
Lastly, in order to get the benefit
of 5.1, 6.1, 7.1 or more, you must have the right speaker
setup. You should have at least 5 speakers (Front-left,
Front-center, Front-right, Surround-left, and
Surround-right) and a subwoofer connected to your audio
receiver or amplifier.