Dolby Laboratories

From Academic Kids

This article is about the company. Dolby may also refer to the engineer Ray Dolby or the musician Thomas Dolby

Dolby Laboratories, Incorporated (Dolby Labs) is a company specializing in audio compression and reproduction.



Dolby Labs was founded by Ray Dolby in England in 1965. He moved the company to the United States in 1976. The first product he made was Type A Dolby Noise Reduction, a simple compander. One of the features that set Dolby's compander apart was that it treated only the quiet sounds that would be masked by tape noise. Dolby marketed the product to record companies.

Dolby was persuaded by Henry Kloss of KLH to manufacture a consumer version of his noise reduction. Dolby worked more on companding systems and introduced B-type in 1968.

Dolby did not manufacture consumer products outright; it licensed the technologies to consumer electronics manufacturers.

Dolby also sought to improve film sound, which at the time was optical and monaural. In 1975 Dolby released Dolby Stereo, which included a noise reduction system in addition to more audio channels (Dolby Stereo could actually contain additional center and surround channels). Dolby reworked the system slightly and introduced Dolby Surround and Dolby Pro Logic.

Dolby developed a digital surround sound compression scheme for the cinema. Dolby Digital was first featured on the 1992 film Batman Returns. Introduced to the home theater market with the 1995 laserdisc release of Stargate, the format didn't become widespread in the consumer market, partly because of extra hardware that was necessary to make use of it, until it was adopted as part of the DVD specification. Dolby Digital is now found in the HDTV (ATSC) standard of the USA, DVD players, and many satellite-TV and cable-TV receivers.

On March 15, 2005, Dolby celebrated 40 Years of enhancing entertainment at the ShoWest 2005 Festival in San Francisco.


  • Dolby Stereo or simply Dolby Analog is the original analog optical technology developed for 35 mm prints and is encoded with four sound channels: Left/Center/Right (which are located behind the screen) and Surround (which is heard over speakers on the sides and rear of the theatre) for ambient sound and special effects.
  • Dolby_Analog_SR or simply Dolby SR (Spectral Recording) is a professional four-channel noise reduction system in use since 1986, which improves the dynamic range of analog recordings and transmissions by as much as 25 dB. Dolby SR is utilized by recording and postproduction engineers, broadcasters, and other audio professionals. It is also the benchmark in analog film sound, being included today on nearly all 35 mm film prints. On films with digital soundtracks, the SR track is used in cinemas not equipped for digital playback, and it serves as a backup in case of problems with the digital track.
  • Dolby Digital (AC-3) delivers digital audio via 5.1 discrete channels. The three front channels (Left/Center/Right) deliver crisp, clean dialogue and accurate placement of on-screen sounds, while twin surround channels (Left Surround/Right Surround) wrap around the audience and immerse them in the action. The LFE (Low-Frequency Effects) channel delivers real impact for explosions and other effects that can, literally, be felt as well as heard. Used in DVDs and cinemas and on digital satellite (DBS), cable, and DTV and HDTV terrestrial services. It can also be used to deliver 5.1 surround radio services.
  • Dolby Digital Surround EX introduces a center rear channel to the 5.1 playback format of Dolby Digital.
  • Dolby Digital Plus is an audio codec based on and compatible with Dolby Digital, but more advanced. The DVD Forum has selected Dolby Digital Plus as a standard audio format for HD-DVD video. Dolby Digital Plus can also be applied to limited bandwidth environments such as broadcast television.
  • Dolby A/B/C/S-Type NR, noise reduction systems for tapes and analog cassettes, see Dolby noise reduction system
  • Dolby Pro Logic, Dolby Pro Logic II, Dolby Pro Logic IIx
  • Dolby E is a professional coding system optimized for the distribution of surround and multichannel audio through two-channel postproduction and broadcasting infrastructures, or for recording surround audio on two audio tracks of conventional digital video tapes, video servers, communication links, switchers, and routers. The Dolby E signal does not reach viewers at home. It is decoded back to baseband audio just prior to the final DTV transmission and then re-encoded into the final audio format specified by the various DTV emission systems.
  • MLP Lossless is a true "lossless" coding system specified for DVD-Audio that compacts PCM data with bit-for-bit accuracy, unlike "lossy" perceptual coding systems such as Dolby Digital. MLP Lossless effectively doubles disc space without affecting the quality of high-resolution PCM audio, making it possible for DVD-Audio discs to carry both stereo and multichannel mixes of the same program. All DVD-Audio players are equipped with MLP Lossless decoding, while its use on the discs themselves is at their producers' discretion.
  • Dolby HX Pro Single-ended system used on high-end tape recorders to increase headroom. The recording Bias is varied with respect to the high frequency component of the signal being recorded. No coding/decoding is used.

See also

  • dBX (analog noise reduction competitor)
  • DTS (digital soundspace competitor)
  • Dolby vs DTS

External links

de:Dolby es:Dolby fr:Dolby ja:ドルビーラボラトリーズ pt:Dolby


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