Dolby Digital
[1] It is a modification of the discrete cosine transform (DCT) algorithm, which was proposed by Nasir Ahmed in 1972 for image compression.[3] Dolby Laboratories adapted the MDCT algorithm along with perceptual coding principles to develop the AC-3 audio format for cinema.Almost all modern cinema prints are of this type and may also include SDDS data and a timecode track to synchronize CD-ROMs carrying DTS soundtracks.In 1991, a limited experimental release of Star Trek VI: The Undiscovered Country in Dolby Digital played in 3 US theatres.[21][22] In 1995, the LaserDisc version of Clear and Present Danger featured the first home theater Dolby Digital mix, quickly followed by True Lies, Stargate, Forrest Gump, and Interview with the Vampire among others.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.[21][26] Dolby Digital Surround EX has since been used on the DVD releases of the Star Wars prequel and original trilogies.[26] 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 a 5.1-channel 16-bit/48 kHz Dolby Digital format at 640 kbit/s and transports it via a single S/PDIF cable.NVIDIA later decided to drop DDL support in their motherboards due to the cost of involved royalties, leaving an empty space in this regard in the sound cards market.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.[30] Creative Labs alleged Kawakami violated their intellectual property and demanded he cease distributing his modified drivers.It offers increased bitrates (up to 6.144 Mbit/s), support for even more audio channels (up to 15.1 discrete channels[36] in the future), and improved coding techniques (only at low data rates) to reduce compression artifacts, enabling lower data rates than those supported by AC-3 (e.g. 5.1-channel audio at 256 kbit/s).It is not backward compatible with existing AC-3 hardware, though E-AC-3 codecs generally are capable of transcoding to AC-3 for equipment connected via S/PDIF.DVD-Video discs are limited to 448 kbit/s, although many players can successfully play higher-rate bitstreams (which are non-compliant with the DVD specification).Some Sony PlayStation 2 console games are able to output AC-3 standard audio as well, primarily during pre-rendered cutscenes.[40] Specific demodulators and receivers from the LaserDisc era (1990s thru early 2000s) also include placement of this term on connectors.
audio compressionDolby LaboratoriesDolby StereoBlu-rayaudio coding standardmodified discrete cosine transformdiscrete cosine transformNasir Ahmedimage compressionUniversity of Surreyperceptual codingcinemaBatman Returnsrelease printcharge-coupled deviceimage projectorbitstreamSony Dynamic Digital Soundtime codeDolby Surround 7.1Dolby AtmosFilename extensionInternet media typeUniform Type Identifier (UTI)backronymsubwooferlow-frequency effectsstereoLaserDiscClear and Present Dangerhome theaterTrue LiesStargateForrest GumpInterview with the VampirePro Logicmatrixcenter surround channelextra surround channelcenter channelLucasfilm Ltd.S/PDIFDTS ConnectSoundStormnForce2RealtekC-MediaAuzentechDolby Digital Plusbitratesaudio channelscompression artifactscodecstranscodingHD DVDBlu-ray DiscDolby AC-4Dolby TrueHDMeridian Lossless Packing5-channel surrounddownmixingDVD-VideoDVD-AudioSyncwordbig endianCyclic redundancy checkSampling frequencyVLC media playerGNU General Public LicenseFFmpegDialnormDolby noise-reduction systemcompact cassetteDolby SRDolby SurroundDolby Pro LogicDolby EDTS (sound system)Home cinemaLoudspeakerAudio Engineering Society ConventionAhmed, NasirDigital Signal ProcessingBibcodeSpringer Science & Business MediaThe New York TimesApple IncAdvanced Television Systems CommitteeAnandTechCreative TechnologyDolby 3DDolby CinemaDolby HeadphoneDolby Surround/Pro Logic/Pro Logic IIDolby VisionDolby VoiceDoremi LabsCineAssetCineExportCinePlayerRay DolbyDolby Theatreaudio recording formatsMechanicalPunched cardMusic rollAnalogPhonautogramcylinderGraphophoneDictaphone cylinderIndestructible recordBlue Amberol recordPhonograph recordDiamond discSoundScriberAudographLong playHighway Hi-FiDictabeltSound-on-filmPhonofilmTri-ErgonMovietonePhotophoneFantasound