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.
Eventually Creative struck an agreement with Dolby Laboratories regarding the Dolby license royalty by arranging that the licensing cost be folded into the purchase price of the Creative X-Fi PCI cards rather than as a royalty paid by Creative themselves.Based on the agreement, in September 2008 Creative began selling the Dolby Digital Live packs enabling Dolby Digital Live on Creative's X-Fi PCI series of sound cards. Subsequently Creative added their DTS Connect pack to the DDL pack at no added cost. The discontinued HD DVD system directly supported E-AC-3.A number of DVDs have a Dolby Digital Surround EX audio option.The cinema version of Dolby Digital EX was introduced in 1999, when Dolby and Skywalker Sound, a division of Lucasfilm Ltd., codeveloped Dolby Digital Surround EX™ for the release of Star Wars: Episode I – The Phantom Menace.Initially no Creative X-Fi based sound cards supported DDL (2005~2007) but a collaboration of Creative and Auzentech resulted in the development of the Auzentech Prelude, the first X-Fi card to support DDL.
Originally planned to extend DDL support to all X-Fi based sound cards (except the 'Xtreme Audio' line which is incapable of DDL hardware implementation), the plan was dropped because Dolby licensing would have required a royalty payment for all X-Fi cards and, problematically, those already sold.
HDMI was later introduced, and it can carry uncompressed multichannel PCM, lossless compressed multichannel audio, and lossy compressed digital audio.
However, Dolby Digital Live is still useful with HDMI to allow transport of multichannel audio over HDMI to devices that are unable to handle uncompressed multichannel PCM.
The analogue soundtrack provides a fall-back option in case of damage to the data area or failure of the digital decoding; it also provides compatibility with projectors not equipped with digital soundheads.
Almost all current release cinema prints are of this type and may also include SDDS data and a timecode track to synchronize CD-ROMs carrying DTS 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 with Surround EX decoding and added speakers.