Dolby Digital 5.1 Surround Sound

Posted : admin On 4/23/2019
Most common speaker configuration for 5.1; used by Dolby Digital, SDDS, DTS, THX, and Pro Logic II. Each black square depicts a speaker. The centre speaker in the top line of the square is used for dialogue. The left and right speakers on either side of the centre speaker are used to create stereo sound for music and other sound effects in the film. The left and right rear speakers create the surround sound effect.

5.1 surround sound ('five-point one') is the common name for six channel surround sound audio systems. 5.1 is the most commonly used layout in home theatre.[citation needed] It uses five full bandwidth channels and one low-frequency effects channel (the 'point one').[1]Dolby Digital, Dolby Pro Logic II, DTS, SDDS, and THX are all common 5.1 systems. 5.1 is also the standard surround sound audio component of digital broadcast and music.[2]

All 5.1 systems use the same speaker channels and configuration, having a front left and right, a center channel, two surround channels and the low-frequency effects channel designed for a subwoofer.

  • 2Application

History[edit]

A prototype for five-channel surround sound, then dubbed 'quintaphonic sound', was used in the 1975 film Tommy.[3]

5.1 dates back to 1976[citation needed] when Dolby Labs modified the track usage of the six analogue magnetic soundtracks on Todd-AO 70 mm film prints. The Dolby application of optical matrix encoding in 1976 (released on the film, Logan's Run) did not use split surrounds, and thus was not 5.1. Dolby first used split surrounds with 70mm film, notably in 1979 with Apocalypse Now. Instead of the five screen channels and one surround channel of the Todd-AO format, Dolby Stereo 70 mm Six Track provided three screen channels, two high-passed surround channels and a low-frequency surround channel monophonically blended with the two surround channels.

When digital sound was applied to 35 mm release prints, with Batman Returns in 1992, the 5.1 layout was adopted. The ability to provide 5.1 sound had been one of the key reasons for using 70 mm for prestige screenings. The provision of 5.1 digital sound on 35 mm significantly reduced the use of the very expensive 70 mm format. Digital sound and the 5.1 format were introduced in 1990, by KODAK and Optical Radiation Corporation, with releases of Days of Thunder and The Doors using the CDS (Cinema Digital Sound) format.

5.1 digital surround, in the forms of Dolby Digital AC3 and DTS, started appearing on several mid 90s Laserdisc releases, with among the earliest being Clear and Present Danger and Jurassic Park (the latter having both AC3 and DTS versions). Many DVD releases have Dolby Digital tracks up to 5.1 channels, due to the implementation of Dolby Digital in the development of the DVD format. In addition, some DVDs have DTS tracks with most being 5.1 channel mixes (a few releases, however, have 6.1 “matrixed” tracks). Blu-ray and digital cinema both have eight-channel capability which can be used to provide either 5.1 or 7.1 surround sound. 7.1 is an extension of 5.1 that uses four surround zones: two at the sides and two at the back.

A system of digital 5.1 surround sound has also been used in 1987 at the Parisian cabaret the Moulin Rouge, created by French engineer Dominique Bertrand. To achieve such a system in 1985 a dedicated mixing console had to be designed in cooperation with Solid State Logic, based on their 5000 series, and dedicated speakers in cooperation with APG.[4] The console included ABCDEF channels. Respectively: A left, B right, C centre, D left rear, E right rear, F bass. The same engineer had already developed a similar 3.1 system in 1973, for use at the official International Summit of Francophone States in Dakar.

Application[edit]

Channel order[edit]

The order of channels in a 5.1 file is different across file formats. The order in WAV files is (not complete) Front Left, Front Right, Center, Low-frequency effects, Surround Left, Surround Right.[5]

Music[edit]

Suggested configuration for 5.1 music listening.

The maze runner movie download. Regarding music, the main goal of 5.1 surround sound is a proper localization and equability of all acoustic sources for a centered positioned audience. Therefore, ideally five matched speakers should be used.

For play-back of 5.1 music recommendations of the International Telecommunication Union (ITU) have been released and propose the following configuration (ITU-R BS 775):[6]

  • five speakers of the same size for front, center and surround
  • identical distance from the listeners for all five speakers
  • angle adjustment regarding viewing direction of audience: center 0°, front ±22.5° for movies ±30° for music, surround ±110°

See also[edit]

References[edit]

  1. ^'Understanding Surround Sound Formats'. Crutchfield.com. 23 September 2009. Retrieved 7 March 2011.
  2. ^'What is 5.1'. Archived from the original on 17 March 2012.
  3. ^Mosely, John (January 1977). 'Quintaphonic Sound'. Journal of the SMPTE. l86.
  4. ^'Recherche & Développement'. Archived from the original on 3 August 2008. Retrieved 17 December 2015.
  5. ^'Multiple channel audio data and WAVE files'. Retrieved 19 November 2015.
  6. ^Thomas Lund (1 September 2000), Enhanced Localization in 5.1 Production, Audio Engineering Society, retrieved 19 November 2015
Retrieved from 'https://en.wikipedia.org/w/index.php?title=5.1_surround_sound&oldid=895239219'
Dolby Digital logo

Dolby Digital is the name for audio compression technologies developed by Dolby Laboratories. Originally named Dolby Stereo Digital until 1994, except for Dolby TrueHD, the audio compression is lossy. The first use of Dolby Digital was to provide digital sound in cinemas from 35mm film prints; today, it is now also used for other applications such as TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles.

  • 2Versions

In the cinema[edit]

Batman Returns was the first film to use Dolby Digital technology when it premiered in theaters in the summer of 1992.[1] Dolby Digital cinema soundtracks are optically recorded on a 35 mmrelease print using sequential data blocks placed between every perforation hole on the sound track side of the film. A constant bit rate of 320 kbit/s is used. A charge-coupled device (CCD) scanner in the image projector picks up a scanned video image of this area, and a processor correlates the image area and extracts the digital data as an AC-3 bitstream. The data is then decoded into a 5.1 channel audio source. All film prints with Dolby Digital data also have Dolby Stereo analogue soundtracks using Dolby SR noise reduction and such prints are known as Dolby SR-D prints. 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.

A Dolby Digital Penthouse Soundhead mounted on a mid-1950s vintage Kalee model 20 projector
A photo of a 35 mm film print featuring all four audio formats (or quad track)- from left to right: Sony Dynamic Digital Sound (SDDS) (blue area to the left of the sprocket holes), Dolby Digital (grey area between the sprocket holes labelled with the Dolby Double-D logo in the middle), analog optical sound (the two white lines to the right of the sprocket holes), and the DTStime code (the dashed line to the far right.)

The simplest way of converting existing projectors is to add a so-called penthouse digital soundhead above the projector head. However, for new projectors it made sense to use dual analogue/digital soundheads in the normal optical soundhead position under the projector head. To allow for the dual-soundhead arrangement the data is recorded 26 frames ahead of the picture. If a penthouse soundhead is used, the data must be delayed in the processor for the required amount of time, around 2 seconds. This delay can be adjusted in steps of the time between perforations, (approximately 10.4 ms).

As of 2015, Dolby Digital in film sound mixing is being gradually replaced with Dolby Surround 7.1, with the more advanced Dolby Atmos technology also gaining in popularity. While majority of movie theaters currently utilize Dolby Digital, virtually all films released today are mixed in Dolby Surround 7.1 and Dolby Atmos.

Versions[edit]

Dolby Digital[2] has similar technologies, included in Dolby Digital EX,[3] Dolby Digital Live,[4] Dolby Digital Plus,[5] Dolby Digital Surround EX,[6] Dolby Digital Recording,[7] Dolby Digital Cinema,[8] Dolby Digital Stereo Creator[9] and Dolby Digital 5.1 Creator.[10]

Dolby Digital[edit]

Dolby Digital logo that is sometimes shown at the start of broadcasts, feature films, and video games
The former Dolby Digital logo

Dolby Digital is the common version containing up to six discrete channels of sound. The most elaborate mode in common use involves five channels for normal-range speakers (20 Hz – 20,000 Hz) (right, center, left, right surround, left surround) and one channel (20 Hz – 120 Hz allotted audio) for the subwoofer driven low-frequency effects.[11]Mono and stereo modes are also supported. AC-3 supports audio sample-rates up to 48 kHz.

This format has different names:

  • Dolby Digital
  • DD (an abbreviation for Dolby Digital, often combined with channel count; for instance, DD 2.0, DD 5.1)
  • AC-3 (Audio Codec 3, Advanced Codec 3, Acoustic Coder 3. [These are backronyms. Adaptive Transform Acoustic Coding 3 is a separate format developed by Sony.])[12]
  • ATSC A/52 (name of the standard)[13]
  • Before 1996, was marketed as Dolby Surround AC-3, Dolby Stereo Digital, and Dolby SRD.[14]

In 1991, a limited experimental release of Star Trek VI: The Undiscovered Country in Dolby Digital played in 3 US theatres.[14] In 1992, Batman Returns is the first movie to be released in Dolby Digital.[15][16] 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.[17][18]

Dolby Digital EX[edit]

Dolby Digital EX is similar in practice to Dolby's earlier Pro-Logic format, which utilized matrix technology to add a center surround channel 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.

Dolby Digital Surround EX[edit]

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 Pro Logic 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 with Surround EX decoding and added speakers.Dolby Digital Surround EX has since been used for the Star Wars prequels on the DVD versions and also the remastered original Star Wars trilogy. 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.[15][19] Dolby Digital Surround EX has since been used for the Star Wars prequels on the DVD versions and also the remastered original Star Wars trilogy.[19]

A Dolby home theater badge on a laptop

Dolby Digital Live[edit]

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.[20] 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 digital PCM stereo or analog multichannel sound because S/PDIF over RCA, BNC, and TOSLINK can only support two-channel PCM, Dolby Digital multichannel audio, and DTS multichannel audio. 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.

Dolby Digital Live is available in sound cards using various manufacturers' audio chipsets. The SoundStorm, used for the Xbox game console and certain nForce2 motherboards, used an early form of this technology. DDL is available on motherboards with codecs such as Realtek's ALC882D,[21] ALC888DD and ALC888H. Other examples include some C-Media PCI sound cards and Creative Labs' X-Fi and Z series sound cards, whose drivers have enabled support for DDL.

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.Then in June 2005 came Auzentech, which with its X-Mystique PCI card, provided the first consumer sound card with Dolby Digital Live support.

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.[22]In 2008, Creative released the X-Fi Titanium series of sound cards which fully supports Dolby Digital Live while leaving all PCI versions of Creative X-Fi still lacking support for DDL.

Since September 2008, all Creative X-Fi based sound cards support DDL (except the 'Xtreme Audio' and its based line such as Prodigy 7.1e, which is incapable of DDL in hardware). X-Fi's case differs.

While they forgot about the plan, programmer Daniel Kawakami made a hot issue by applying Auzentech Prelude DDL module back to Creative X-Fi cards by disguising the hardware identity as Auzentech Prelude.[23]

Creative Labs alleged Kawakami violated their intellectual property and demanded he cease distributing his modified drivers.[24][25][26]

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.[22] 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. It can be purchased and downloaded from Creative. Subsequently Creative added their DTS Connect pack to the DDL pack at no added cost.[27]

Dolby Digital Plus[edit]

E-AC-3 (Dolby Digital Plus) is an enhanced coding system based on the AC-3 codec. It offers increased bitrates (up to 6.144 Mbit/s), support for even more audio channels (up to 15.1 discrete channels[28] 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. E-AC-3 decoders can also decode AC-3 bitstreams. The fourth generation Apple TV supports E-AC-3.[29] The discontinued HD DVD system directly supported E-AC-3. Blu-ray Disc offers E-AC-3 as an option to graft added channels onto an otherwise 5.1 AC-3 stream, as well as for delivery of secondary audio content (e.g. director's commentary) that is intended to be mixed with the primary audio soundtrack in the Blu-ray Disc player.

Dolby AC-4[edit]

Dolby AC-4 is an audio compression standard supporting multiple audio channels and/or audio objects. Support for 5.1 channel audio is mandatory and additional channels up to 7.1.4 are optional.[30] AC-4 provides a 50% reduction in bit rate over AC-3/Dolby Digital Plus.[30]

Dolby TrueHD[edit]

Dolby TrueHD, developed by Dolby Laboratories, is an advanced lossless audio codec based on Meridian Lossless Packing. Support for the codec was mandatory for HD DVD and is optional for Blu-ray Disc hardware. Dolby TrueHD supports 24-bit bit depths and sample rates up to 192 kHz. Maximum bitrate is 18 MBit/s while it supports up to 16 audio channels (HD DVD and Blu-ray Disc standards currently limit the maximum number of audio channels to eight). It supports metadata, including dialog normalization and Dynamic Range Control.

Channel configurations[edit]

Although commonly associated with the 5.1 channel configuration, Dolby Digital allows a number of different channel selections. The options are:

  • Dolby Digital 1/0 - Mono (center only)
  • Dolby Digital 2/0 - 2-channel stereo (left + right), optionally carrying matrixed Dolby Surround
  • Dolby Digital 3/0 - 3-channel stereo (left, center, right)
  • Dolby Digital 2/1 - 2-channel stereo with mono surround (left, right, surround)
  • Dolby Digital 3/1 - 3-channel stereo with mono surround (left, center, right, surround)
  • Dolby Digital 2/2 - 4-channel quadraphonic (left, right, left surround, right surround)
  • Dolby Digital 3/2 - 5-channel surround (left, center, right, left surround, right surround)

These configurations optionally include the extra low-frequency effects (LFE) channel. The last two with stereo surrounds optionally use Dolby Digital EX matrix encoding to add an extra Rear Surround channel.

Many Dolby Digital decoders are equipped with downmixing to distribute encoded channels to speakers. This includes such functions as playing surround information through the front speakers if surround speakers are unavailable, and distributing the center channel to left and right if no center speaker is available. When outputting to separate equipment over a 2-channel connection, a Dolby Digital decoder can optionally encode the output using Dolby Surround to preserve surround information.

The '.1' in 5.1, 7.1 etc. refers to the LFE channel, which is also a discrete channel.

Applications[edit]

Dolby Digital audio is used on DVD-Video and other purely digital media, like home cinema. In this format, the AC-3 bitstream is interleaved with the video and control bitstreams.

The system is used in bandwidth-limited applications other than DVD-Video, such as digital TV. The AC-3 standard allows a maximum coded bit rate of 640 kbit/s. 35mm film prints use a fixed rate of 320 kbit/s, which is the same as the maximum bit rate for 2-channel MP3. 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). HD DVD limits AC-3 to 448 kbit/s. ATSC and digital cable standards limit AC-3 to 448 kbit/s. Blu-ray Disc, the PlayStation 3 and the Xbox game console can output an AC-3 signal at a full 640 kbit/s. Some Sony PlayStation 2 console games are able to output AC-3 standard audio as well, primarily during pre-rendered cutscenes.

Dolby is part of a group of organizations involved in the development of AAC (Advanced Audio Coding), part of MPEG specifications, and considered the successor to MP3.

Dolby Digital Plus (DD-Plus) and TrueHD are supported in HD DVD, as mandatory codecs, and in Blu-ray Disc, as optional codecs.

Dolby technologies in packaged media formats[edit]

HD DVDBlu-ray DiscDVD-VideoDVD-AudioLaserDisc
CodecPlayer supportChannels (max)Max bit ratePlayer supportChannels (max)Max bit ratePlayer supportChannels (max)Max bit ratePlayer supportChannels (max)Max bit ratePlayer supportChannels (max)Max bit rate
Dolby DigitalMandatory5.1504 kbit/sMandatory5.1640 kbit/sMandatory5.1448 kbit/sOptional in video zone for playback compatibility on DVD-Video players5.1448 kbit/sOptional5.1384 kbit/s
Dolby Digital Plus7.13 Mbit/sOptional7.11.7 Mbit/s
N/A
Dolby TrueHD7.118 Mbit/s7.118 Mbit/s

Technical details[edit]

The data layout of AC-3 is described by simplified 'C-like' language in official specifications. An AC-3 stream is a series of frames; The frame size code is used along with the sample rate code to determine the number of (2-byte)words before the next syncword. Channel blocks can be either long, in which case the entire block is processed as single modified discrete cosine transform or short, in which case two half length transforms are performed on the block. Below is a simplified AC-3 header. A detailed description is in the ATSC 'Digital Audio Compression (AC-3) (E-AC-3) Standard', section 5.4.

Field Name# of bitsDescription
Syncword160x0B77, data transmission is left bit first: big endian
Cyclic redundancy check16
Sampling frequency2'11'=reserved '10'=32 kHz '01'=44.1 '00'=48
Frame size code6
Bit stream identification5
Bit stream mode3'000'=main audio service
Audio coding mode3'010'=left, right channel ordering
Center mix level2
Surround mix level2
Dolby Surround mode2'00'=not indicated '01'= Not surround encoded '10'= Yes, surround encoded

liba52[edit]

A free ATSC A/52 stream decoder, liba52, is available under the GPL license.

License[edit]

Audio codec AC3 is covered by patents (though these are now expired[31]). Patents are used to ask to pay a commercial license to publish an application that decodes AC3. This leads some audio app developers to ban AC3 from their apps, although the open source VLC media player supports AC-3 audio without having paid for any kind of patent license.[32]

In Dolby's 2005 original and amended S-1 filings with the SEC, Dolby acknowledged that 'Patents relating to our Dolby Digital technologies expire between 2008 and 2017.'[33][34][35]

The last patent covering AC-3 expired March 20, 2017, so it is now generally free to use.[36]

See also[edit]

  • C-Media – producer of DDL audio chipsets used in many sound cards and motherboards
  • Dialnorm – Dolby Digital metadata parameter controlling decoder gain
  • Dolby Laboratories – company history and technology development
  • Dolby noise-reduction system – analogue recording on magnetic tape, including compact cassette tapes
  • Dolby Stereo – first cinema analogue surround sound system
  • Dolby SR - professional analogue recording on magnetic tape
  • Dolby Surround - renamed Pro Logic in 1987
  • Dolby Pro Logic – consumer version of the Dolby Stereo analogue surround sound system
  • Dolby TrueHD – lossless codec for HD DVD and Blu-ray Disc
  • Dolby E - allows 6 to 8 channels of audio to be compressed into an AES-EBU digital audio stream
  • DTS (sound system) – formerly Digital Theater Systems
  • SoundStorm – a real-time AC-3 encoder included in certain nForce2 motherboards

References[edit]

  1. ^'COMPANY NEWS: A Sound Idea; Dolby Theater Format Adapted to Home Uses'. The New York Times.
  2. ^'Dolby - Dolby Digital Details'. Dolby Laboratories.
  3. ^'Dolby - What is Dolby Digital EX?'. Dolby Laboratories.
  4. ^'Dolby - What is Dolby Digital Live?'. Dolby Laboratories.
  5. ^'Dolby - Dolby Digital Plus Details'. Dolby Laboratories.
  6. ^'Dolby - What is Dolby Digital Surround EX?'. Dolby Laboratories.
  7. ^'Dolby - What is Dolby Digital Recording?'. Dolby Laboratories.
  8. ^'Dolby - Dolby Digital Cinema Details'. Dolby Laboratories.
  9. ^'Dolby - Dolby Digital Stereo Creator Details'. Dolby Laboratories.
  10. ^'Dolby - What is Dolby Digital 5.1 Creator?'. Dolby Laboratories.
  11. ^'Dolby-Frequently Asked Questions'(PDF). Dolby Laboratories.
  12. ^'Sony USA'. Sony.
  13. ^'A/52B: Digital Audio Compression (AC-3) (E-AC-3) Standard, Rev. B'. Advanced Television Systems Committee.
  14. ^ ab'Movie Sound Chronology'. spannerworks.net. Retrieved 2017-04-02.
  15. ^ ab'History: 50 YEARS OF INNOVATION'. Dolby Laboratories. Retrieved 2017-03-22.
  16. ^'`Batman Returns` To Try Double Dolby'. The Chicago Tribune. May 13, 1992. Retrieved 2017-03-22.
  17. ^'Laserdisc Database Search By Date'. Laserdisc Database. Retrieved 2017-04-02.
  18. ^'LaserDisc Database Clear and Present Danger'. LaserDisc Database. Retrieved 2017-04-02.
  19. ^ ab'Dolby Launches Dolby Digital Cinema in Theatres Worldwide with Star Wars Episode III: Revenge of the Sith'. Dolby Investor Relations. Retrieved 2017-03-22.
  20. ^'Dolby Digital Live'. Dolby Laboratories.
  21. ^Key, Gary (June 8, 2006). 'Nvidia nForce 500: Biostar and MSI Aim for the Gold'. AnandTech.
  22. ^ ab'A Korean reply comment (the fifth), which explains Dolby license royalty issue of X-Fi. Since the information leaked from SoundPrime, the Korean partner of Auzentech, all sources about this information are Korean'.
  23. ^'What Daniel_K wrote to the public is 'This utility was written from scratch and does not contain any copyrighted code. Creative's director of developer relations, George Thorn told me, in a chat session, that is OK to provide mods as patches. It does not modify any executable or DLL, so it is NOT a crack.' Daniel_K's driver MOD itself did not include any DDL module, until it began to support Creative's official DDL pack. Daniel_K's 'DDLUnlocker.exe' merely used disguise to install Auzentech Prelude DDL module'.
  24. ^Beschizza, Rob (April 1, 2008). 'Daniel_K, Who Fixed Creative's Broken Vista Drivers, Speaks Out'. Wired.com.
  25. ^'There is BrokenBlaster blame about CL - Creative Labs, its much later than the issue but show common case who blame Creative Labs and admire Daniel_K'. Creative Technology.
  26. ^Beschizza, Rob (March 31, 2008). 'Silence From Sound Card Maker After Customer Revolt'. Wired.
  27. ^'Dolby Digital Live pack, its DDL pack but also say 'Get DTS Connect Pack FREE! for every purchase of Dolby Digital Live Pack.''. Creative Technology.
  28. ^'Dolby Digital Plus Audio Coding Tech Paper'(PDF).
  29. ^'Apple TV - Tech Specs'. Retrieved 1 January 2017.
  30. ^ ab'Dolby AC-4: Audio Delivery for Next-Generation Entertainment Services'(PDF). Dolby Laboratories. 2015-06-01. Retrieved 2016-04-26.
  31. ^https://ac3freedomday.org/
  32. ^VideoLAN. 'VideoLAN - VLC - Features'. Retrieved 1 January 2017.
  33. ^'SEC Form S-1'. ADOBE investor relations website. Retrieved 2017-03-22.
  34. ^'SEC Form S-1'. United States Securities and Exchange Commission (SEC) EDGAR system, filed November 19, 2004. Retrieved 2017-03-22.
  35. ^'Amendment No. 1 to SEC Form S-1'. United States Securities and Exchange Commission (SEC) EDGAR system, amended February 12, 2005. Retrieved 2017-03-22.
  36. ^'The last patent on AC-3 (Dolby Digital) expires at midnight Hacker News'. news.ycombinator.com. Retrieved 2017-05-06.

External links[edit]

Wikimedia Commons has media related to Dolby Digital.
  • Official website, Dolby Laboratories
  • Digital Audio Compression Standard (AC-3, E-AC-3) at the ATSC website
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