DD is a surround system using the digital audio compression technology. It is a six channel configuration and reproduces sound through a speaker system including front (L&R), rear (L&R), centre and sub-woofer speakers. Because the sub-woofer in the system is an auxiliary speaker, the system is called "5.1 channel system". In a Digital Versatile Disc, the surround audio data is recorded digitally in a bit-stream.

Dolby® Digital technology is an advanced form of digital audio coding that makes it possible to store and transmit high-quality digital sound far more efficiently than was previously possible. First used in movie theaters in 1992, Dolby Digital technology is the result of decades spent by Dolby Laboratories developing signal-processing systems that exploit the characteristics of human hearing.

Dolby Digital programs can deliver surround sound with up to five discrete full-range channels: Left, Center, Right, Left Surround, Right Surround-plus a sixth channel for powerful low-frequency effects. As it needs only about one-tenth the bandwidth of the others, the LFE channel is referred to as a ".1" channel (and sometimes erroneously as the "subwoofer" channel).

Discs in countries such as the US that use the NTSC broadcast TV standard must provide at least one soundtrack in either of two formats: Dolby Digital or PCM (the format used on CDs). In countries using the PAL TV standard, including much of Europe, the discs must include at least one soundtrack in any one of three formats: Dolby Digital, PCM, or MPEG. Due to these requirements and the options they permit, not all discs may have Dolby Digital soundtracks.

Dolby digital is a sound format featuring six-channel sound with separate left and right sounds and a low frequency-effects channel. Dolby digital is a standard when it comes to sound formats for DVDs, set-top boxes, etc.

The technology behind 5.1-channel Dolby Digital provides two surround channels, instead of the one from Dolby Surround, for more precise localization of sounds and a more convincing, realistic ambience. Also, Dolby Digital's surround channels cover the entire audible range (20 Hz-20,000 Hz), whereas the range of Dolby Surround's single surround channel is limited (100 Hz-7,000 Hz). The increased range of Dolby Digital further heightens realism and gives sound mixers more creative freedom.

Discs in countries such as the U.S. that use the NTSC broadcast TV standard must provide at least one soundtrack in either of two formats: Dolby Digital or PCM (the format used on CDs). In countries using the PAL TV standard, including much of Europe, the discs must include at least one soundtrack in any one of three formats: Dolby Digital, PCM, or MPEG. As a result of these requirements and the options they permit, not all discs have Dolby Digital soundtracks.

Consumer grade DVD recorders all have the ability to play back all Dolby Digital and DTS source material, when used with an AV receiver. However, DVD recorders only have analog stereo audio inputs for recording audio, which is then encoded into two-channel Dolby Digital. The output of the recorded audio can be accessed either through the analog stereo outputs or the digital audio outputs of the DVD recorder. Although, DVD recorders cannot record in 5.

It offers 5.1 channels of audio (Left, Right, Centre, Back Left, Back Right) and a separate channel for the sub woofer. You will need a compatible amplifier to listen to Dolby Digital DVD's however it's benefits for atmosphere when set-up correctly over Dolby Pro Logic and standard stereo are very noticeable.

If you plan to connect the DVD player to a surround-sound receiver that is Dolby Digital ready, then a built-in decoder is necessary. If the receiver has a built-in decoder, the DVD player only needs to have the Dolby Digital passthrough.

Many DVDs offer a choice of sound formats including Dolby Digital and DTS (Digital Theater Systems). The sound is encoded on the DVD so you will need a decoder to experience the full surround sound effect. However, all DVD players will deliver conventional stereo sound without a decoder. Once you have reviewed a movie we check that it is a reasonable length of review and suitable for displaying on the website. This may take a few days.

The DTS sound track on a DVD will be one of three sound tracks available on the disc. A DTS disc will have a stereo, Dolby Digital and DTS soundtrack to choose from. Most discs have an option menu, which allows you to make certain selections regarding audio, language, and other special features. Under the audio option menu, you will find the various selections for the type of sound track you wish to select.

Dolby Digital can be enjoyed via DVDs, DVD recordable and playback discs for computers, laser discs, digital cable systems, direct broadcast satellite (DBS) and direct-to-home (DTH) systems, and digital broadcast television (DTV/DVB). Sources are usually identified with the Dolby Digital logo.

No. Dolby Digital soundtracks can provide anything from mono to full 5.1-channel surround sound. DVDs of movies can even carry multiple versions of the soundtrack that differ in number of channels. A disc might contain a 5.1-channel sound mix with the dialogue in one language, a two-channel mix encoded in Dolby Surround in another language, and a mono track with the director's comments or other supplementary information.

While you won't get the same experience listening to Dolby Digital 5.1 audio on a Dolby Pro Logic system, you will notice a dramatic difference between listening in Dolby 5.1 and 2.0. Of course to take the fullest advantage of 5.1 you'd need a Dolby Digital receiver. Put simply, in order to fit all the information on one side of the DVD, the technology utilizes two layers of information. That delay is the laser reaching the end of layer 1 and finding layer 2.

Yes, Dolby Digital audio is used on DVD-Video discs throughout the world (see question 9). A word of caution, though: while the audio and video technical standards are the same for DVD-Video worldwide, discs purchased in one part of the world may not play at all in another part of the world due to "regional coding.

Most DVD-Video discs contain Dolby Digital soundtracks. However, it's not required. Some discs, especially those containing only audio, have PCM tracks. It's also possible for a 625/50 (PAL) disc to contain only MPEG audio, but so far MPEG audio is not widely used. Don't assume that the "Dolby Digital" label is a guarantee of 5.1 channels. A Dolby Digital soundtrack can be mono, dual mono, stereo, Dolby Surround stereo, etc.

No. You can get started with just a DVD player. DVD players have regular right and left stereo analog output jacks. Simply connect them to an A/V receiver with Dolby Pro Logic or Dolby Surround for surround sound. Also, many DVD players come with Virtual Surround, which creates surround sound with just your 2 speakers, and they don't even need Dolby Pro Logic or surround. The best part is, when you decide to go digital, you can easily upgrade to a Dolby Digital decoder and 6-speaker package.

Dolby Digital AC-3 is a technology developed by Dolby Laboratories that allows us to store much more CD-quality audio in much less space than traditional CD-audio. Dolby Digital also allows us to present soundtracks in the home that offer a complete surround sound experience, just like at the movie theatre, with left, centre, and right channels, stereo surround channels and a subwoofer.

That depends on the computer's configuration and its DVD/audio card, so check the specifications carefully to be sure you get the audio capability you want. Most PCs can be connected to external playback equipment ranging from amplified stereo speakers to a full 5.1-channel playback system. The latter include not only full home theater systems, but compact, multichannel PC speaker systems incorporating amplifiers and Dolby Digital and/or Dolby Surround Pro Logic decoding.

Dolby Digital is a system capable of multi channel digital audio, coded using technology previously known as AC-3, often abbreviated as DD.

Somewhat confusingly, this is actually also a single channel of digital audio. The same audio stream is directed to the front left and front right speakers. Very few discs use this format.

Initially known as simply Dolby Surround, this is an audio mixing technique that bolts on a rear channel and a centre channel onto a standard two-channel signal. With a two speaker sound system, these extra channels will be automatically mixed into the audio streams for the left and right speaker