What is Dolby Digital? 

Dolby Digital Plus (DD+ or E-AC-3), is a digital audio compression scheme developed specifically for the introduction of HDTV and HD DVD/Blu-ray Disc. It is a development of the earlier Dolby Digital system. Compared to Dolby Digital it supports a greater range of bitrates [1] at higher quality and up to thirteen full range audio channels compared with Dolby Digital's five. The compression algorithm also has a number of improvements aimed at increasing quality at a given bitrate compared with Dolby Digital.

Answered by satyaiitk , an ibibo Master, at 7:47 PM on February 27, 2008

well anita, Dolby Digital produces 5 discrete (perfectly separated) sound channels.Also known as Dolby Digital 5.1. Dolby Digital is a six-channel surround system found on many DVDs which sends discrete audio information to speakers at front left, front right, front center, rear left, rear right and a dedicated bass speaker, known as a subwoofer.Most DVD discs contain Dolby Digital soundtracks, but the soundtrack can be Mono, Dual Mono, Stereo or Dolby Surround.

Answered by Uttam , an ibibo Master, at 8:33 PM on February 27, 2008

this is the name given to the marketing company for developing music compression technologies developed by Dolby laboratory
Dolby Digital includes several similar technologies, which include Dolby Digital, Dolby Digital EX, Dolby Digital Live, Dolby Digital Surround EX, Dolby Digital Plus, and Dolby TrueHD.

Answered by Rahul , an ibibo Citizen, at 10:12 PM on February 27, 2008

Dolby Digital is the oldest proprietary digital audio format that is licensed by Dolby Labs.

Almost 100% of all movies made incorporate the dolby audio encoding technology.

To reproduce the dolby effects one needs a dolby cable system. Such dolby systems is found in most movie theaters today. Todays dolby systems incorporate a audio encoding mechanism that involves segregation of audio in movies into multichannel formats like 5.1/6.1/7.1.
5.1 means left/right channel, center channel, 2 surround channel & one low frequency channel. 6. 1 incorporates an additional back surround channel. 7.1 incorporates 2 more back surround channel than the 5.1.

The main left & right channel drive all the main effects, the center channel drives all the speech to simulate the listener to feel the entire speech is coming right off the screen. The surround channel simulates the background effects and the low frequency channel reproduces the entire bass of the recording.

The dolby surround system is also available in all home theater products.

Answered by Kannan , an ibibo Specialist, at 11:24 PM on February 27, 2008

The 5.1-channel digital format created by Dolby Laboratories. In current usage applies both to the company’s 35mm theatrical format (which contains the data printed optically between the sprocket holes) and their video formats (such as DVD, laserdisc, and DTV).

Answered by Romi , an ibibo Master, at 11:17 AM on February 28, 2008

Dolby Digital is an advanced form of digital audio coding technique that reduces the amount of data needed to produce high quality sound.
Dolby Digital delivers 6 channels in the 5.1 configuration: left, right, and center screen channels, separate left and right sounds, and a subwoofer channel. This is sometimes called surround sound or 3D sound.

Answered by Ashish , an ibibo Wizard, at 12:45 PM on February 28, 2008

Dolby Digital, formerly known as AC-3, is a digital audio coding technique that reduces the amount of data needed to produce high quality sound. Dolby Digital takes advantage of how the human ear processes sound. When coding noise is close to the frequency of an audio signal, that audio signal masks the noise so that the human ear hears only the intended audio signal. Sometimes the coding noise is not in the same frequency of an audio signal and must be reduced or eliminated. By reducing, eliminating, or masking the noise, the amount of data is reduced to one tenth of the data on a compact disk (CD). Dolby Digital is used with digital versatile discs (DVDs), high definition television (HDTV), and digital cable and satellite transmissions. It has been selected as the audio standard for digital television (DTV). The European DVB standard does not use Dolby Digital for audio, but instead uses MPEG standard technology for both the audio and video signals.
Dolby Digital provides five full-bandwidth channels, front left, front right, center, surround left, and surround right, for true surround sound quality. A low frequency effect (LFE) channel is included that provides the sound needed for special effects and action sequences in movies. The LFE channel is one-tenth of the bandwidth of the other channels and is sometimes erroneously called the subwoofer channel. This multichannel scheme is known as 5.1 channel.

Because not everyone has the equipment needed to take advantage of Dolby Digital's 5.1 channel sound, developers included a downmixing feature that ensures compatibility with any playback device. The decoder in the playback device delivers the audio signal specific to that particular device's ability. For example, a 5.1 channel audio signal is delivered to a mono television. The playback device's decoder downmixes the 5.1 channel signal to a mono signal allowing the television to use the received audio signal. Because the playback device does the downmixing, producers do not have to create multiple audio signals for each playback device.

The Advanced Television Systems Committee (ATSC) selected Dolby Digital as a standard for DTV because of its popularity with film producers and consumers, its ability to use a single audio streaming video because of the downmixing feature, and its high quality sound. The U.S. cable television industry has also adopted Dolby Digital for DTV applications. Most television facilities are not equipped to produce 5.1 channel sound. For this reason, many DTV programs use two-channel sound. The 5.1 channel sound is used primarily for theatrical films on pay-per-view channels and at theaters.

To take advantage of Dolby Digital 5.1 channel sound for satellite broadcasts, a satellite receiver that provides a Dolby Digital output is necessary. For cable users, all digital set-top boxes are equipped with a Dolby Digital two-channel decoder. To use 5.1 channel sound, a 5.1 channel-compliant set-top box is needed or an external 5.1 channel decoder unit. The proper sound equipment is also necessary.

Answered by sujata , an ibibo Specialist, at 6:51 PM on February 28, 2008

Dolby Digital


Dolby Digital logo that is sometimes shown at the beginning of broadcasts, feature films, and games
Dolby Digital, or AC-3, is the common version containing up to six discrete channels of sound, with five channels for normal-range speakers (20 Hz – 20,000 Hz) (right front, center, left front, right rear and left rear) and one channel (20 Hz – 120 Hz) for the subwoofer driven low-frequency effects. Mono and stereo modes are also supported. AC-3 supports audio sample-rates up to 48KHz. Batman Returns was the first film to use Dolby Digital technology when it premiered in theaters in Summer 1992. The LaserDisc version of Clear and Present Danger featured the very first Home theater Dolby Digital mix in 1995.
This codec has several aliases, which are different names for the same codec:
Dolby Digital (promotional name, not accepted by the ATSC)
DD (an abbreviation of above, often combined with channel count: DD 5.1)
Dolby Surround AC-3 Digital (second promotional name, as seen on early film releases and on home audio equipment until about 1995/1996)
Dolby Stereo Digital (first promotional name, as seen on early releases, also seen on True Lies LaserDisc)
Dolby SR-Digital (when the recording incorporates a Dolby SR-format recording for compatibility)
SR-D (an abbreviation of above)
Adaptive Transform Coder 3 (relates to the bitstream format of Dolby Digital)
AC-3 (an abbreviation of above)
Audio Codec 3, Advanced Codec 3, Acoustic Coder 3 (These are backronyms. However, Adaptive TRansform Acoustic Coding 3, or ATRAC3, is a separate format developed by Sony)
ATSC A/52 (name of the standard, current version is A/52 Rev. B)
Dolby Digital EX
Dolby Digital EX is similar in practice to Dolby's earlier Pro-Logic format, which utilized Matrix technology to add a center and single rear surround channel to stereo soundtracks. EX adds an extension to the standard 5.1 channel Dolby Digital codec in the form of matrixed rear channels, creating 6.1 or 7.1 channel output. However, the format is not considered a true 6.1 or 7.1 channel codec because it lacks the capability to support a discrete 6th channel unlike the competing DTS-ES codec.
Dolby Digital Live
Dolby Digital Live (DDL) is a real-time encoding technology for interactive media such as video games. It converts any audio signals on a PC or game console into the 5.1-channel Dolby Digital format and transports it via a single S/PDIF cable.[1] The SoundStorm, used for the Xbox game console and certain nForce2-based PCs, used an early form of this technology. Dolby Digital Live is currently available in sound cards from manufacturers such as Turtle Beach[2],HT OMEGA SYSTEM[3] and Auzentech[4] using C-Media chipsets, as well as on motherboards with codecs such as Realtek's ALC882D,[5] ALC888DD and ALC888H. A similar technology known as DTS Connect is available from competitor DTS.
An important benefit of this technology is that it enables the use of digital multichannel sound with consumer sound cards, which are otherwise limited to PCM stereo or multichannel analog.
Dolby Digital Surround EX
Dolby Digital Surround EX was co-developed by Dolby and Lucasfilm THX in time for the release in May 1999 of Star Wars Episode I: The Phantom Menace. It provides an economical and backwards-compatible means for 5.1 soundtracks to carry a sixth, center back surround channel for improved localization of effects. The extra surround channel is matrix encoded onto the discrete Left Surround and Right Surround channels of the 5.1 mix, much like the front center channel on Dolby Surround encoded stereo soundtracks. The result can be played without loss of information on standard 5.1 systems, or played in 6.1 or 7.1 on systems equipped with Surround EX decoding and additional speakers. Dolby Digital Surround EX has since been used for the Star Wars prequels on the DVD versions and

Answered by KUL , an ibibo Citizen, at 9:00 PM on February 28, 2008

this is the marketing name given to company which provide support in compression technologies for audio system

Answered by Shreshtha , an ibibo Master, at 10:01 PM on February 29, 2008