Dolby

History

Dolby Labs was founded by Ray Dolby in England in 1965. He moved the company to the United States (San Francisco, California) 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. As the corporation's history explains:Upon investigation, Dolby found that many of the limitations in optical sound stemmed directly from its significantly high background noise. To filter this noise, the high-frequency response of theatre playback systems was deliberately curtailed… To make matters worse, to increase dialogue intelligibility over such systems, sound mixers were recording soundtracks with so much high-frequency pre-emphasis that high distortion resulted.

The first film with Dolby sound was A Clockwork Orange (1971), which used Dolby noise reduction on all pre-mixes and masters, but a conventional optical sound track on release prints. Callan (1974) was the first film with a Dolby-encoded optical soundtrack. 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 matrixed from the left and right). The first film with a Dolby-encoded stereo optical soundtrack was Lisztomania (1975), although this only used an LCR (Left-Center-Right) encoding technique. The first true LCRS (Left-Center-Right-Surround) soundtrack was encoded on the movie A Star Is Born in 1976. In less than ten years, 6,000 cinemas worldwide were equipped to use Dolby Stereo sound. Dolby reworked the system slightly for home use and introduced Dolby Surround, which only extracted a surround channel, and the more impressive Dolby Pro Logic, which was the domestic equivalent of the theatrical Dolby Stereo.

Dolby developed a digital surround sound compression scheme for the cinema. Dolby Stereo Digital (now simply called Dolby Digital) was first featured on the 1992 film Batman Returns. Introduced to the home theater market as Dolby AC-3 with the 1995 laserdisc release of Clear and Present Danger, the format did not 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 February 17, 2005, the company became public, offering stock for sale on the New York Stock Exchange under the symbol DLB.
On March 15, 2005, Dolby celebrated forty years of enhancing entertainment at the ShoWest 2005 Festival in San Francisco.
On January 8, 2007, Dolby announced the arrival of an entirely new product called Dolby Volume at the International Consumer Electronics Show (CES). This product enables users to maintain a steady volume while switching through channels or program elements (i.e., loud TV commercials).
Dolby Labs has been good to its founder. Ray Dolby is a member of the Forbes 400 with an estimated net worth of 2.7 Billion in 2007.

Technologies

Analog audio noise reduction

Dolby A/B/C/S-Type NR: professional and consumer noise reduction systems for tapes and analog cassettes.Dolby SR (Spectral Recording): 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 post-production 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 FM: noise reduction system for FM broadcast radio. Dolby FM used Dolby B, combined with 25 microsecond pre-emphasis. This system integrated into a small number of receivers, and was used by a few radio stations in the late 1970s and early 1980s. The system is no longer used, however.

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. It does nothing to the actual audio that's being recorded, and doesn't require a special decoder. Any HX Pro recorded tape will have, in theory, better sound on any deck.

Audio encoding/compression

Dolby Digital (also known as AC-3): is a lossy audio compression format. It supports channel configurations from mono up to six discrete channels (referred to as "5.1"). This format first allowed and popularized surround sound. It was first developed for movie theater sound and spread to Laserdisc and DVD. It has been adopted in many broadcast formats including all North American digital television (ATSC), DVB-T, direct broadcast satellite, cable television, DTMB, IPTV, and surround sound radio services. It was also part of Blu-ray and HD DVD standards. Dolby Digital is used to enable surround sound output by most video game consoles. Several personal computers support converting all audio to Dolby Digital for output. Dolby Digital EX: introduces a matrix-encoded center rear surround channel to Dolby Digital for 6.1 channel output.

This center rear channel is often split to two rear back speakers for 7.1 channel output.Dolby Digital Plus: audio codec based on Dolby Digital that is backward compatible, but more advanced. The DVD Forum has selected Dolby Digital Plus as a standard audio format for HD DVD video. It supports datarates up to 6 Mbyte/s, an increase from Dolby Digital's 640 kbit/s maximum. Dolby Digital Plus is also optimized for limited datarate environments such as Digital broadcasting. Dolby-E selected hardware.

Dolby E: professional coding system optimized for the distribution of surround and multichannel audio through digital two-channel post-production 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 transcoded to Dolby Digital at lower datarate for final DTV transmission.Dolby Stereo (also known as Dolby Analog): 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. This technology also employs A-type or SR-type noise reduction, listed above with regards to analog cassette tapes. See also Dolby SurroundDolby TrueHD: Dolby's current lossless coding technology. It offers bit-for-bit sound reproduction identical to the studio master. Over seven full-range 24-bit/96 kHz discrete channels are supported (plus a LFE channel, making it 7.1 surround) along with the HDMI interface. It has been selected as the mandatory format for HD DVD and as an optional format for Blu-ray Disc. Theoretically, Dolby True HD can support more channels, but this number has been limited to 8 for HD DVD and Blu-ray Disc.

Audio processingDolby Headphone: simulates 5.1 surround sound in a standard pair of stereo headphones. Dolby Virtual Speaker: simulates 5.1 surround sound in a setup of two standard stereo speakers. Dolby Pro Logic, Dolby Pro Logic II, Dolby Pro Logic IIx: expands stereo content to surround soundAudistry: sound enhancement technologies Dolby Volume: reduces volume level changes.