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66-514: Dolby Stereo is a sound format made by Dolby Laboratories . It is a unified brand for two completely different basic systems: the Dolby SVA (stereo variable-area) 1976 system used with optical sound tracks on 35mm film, and Dolby Stereo 70mm noise reduction on 6-channel magnetic soundtracks on 70mm prints. Dolby SVA significantly improves the development of sound effects in films and theorization of sound design by Walter Murch . In 1982, it

132-407: A compander -based noise reduction system. These units were intended for use in professional recording studios. 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 Type B in 1968. Dolby also sought to improve film sound. As the corporation's history explains: The first film with Dolby sound

198-410: A CMY color image, but Technicolor's strong preference for variable-density continued long thereafter. Variable-density was finally abandoned as customer preferences for "dual-bilateral" variable-area soundtracks emerged in the late 1950s. This required changes to some laboratory processing and quality controls, but the real reason for variable-density's demise was yet to come. In the early-1970s, there

264-648: A Dolby SR analog soundtrack, both as a backup in case the digital track malfunctions and for theaters not equipped for Dolby Digital playback. As of 2021, Dolby Stereo's market share in the cinema space has declined rapidly with the advent of digital cinema . It serves as a backup for movie theaters still exhibiting 35mm film . The Dolby Stereo Matrix (or Dolby 4:2:4 Matrix ) is straightforward. The four original channels of Left ( L ), Center ( C ), Right ( R ), and Surround ( S ), are combined into two, known as Left-total and Right-total ( LtRt ) by this formula: where j = 90° phase-shift This center channel information

330-445: A Dolby Stereo encoded 35 mm film carries not only left and right tracks for stereophonic sound , but also—through a matrix decoding system ( Dolby Motion Picture matrix or Dolby MP) similar to that developed for " quadraphonic " or "quad" sound in the 1970s—a third center channel , and a fourth surround channel for speakers on the sides and rear of the theater for ambient sound and special effects. This yielded

396-440: A center-channel speaker with a simple mix of the left and right channels; however, this is not entirely satisfactory as it degrades the stereo separation. After he brought his idea and worked with Dolby, Dolby SVA, a 35mm stereo variable-area optical encoding and decoding system, came up and later was adopted as an industry standard--ISO 2969. At this time, Dolby joined forces with Kodak in developing this system. Dolby's solution to

462-404: A manner more akin to how they would have sounded in the theater and for that market some manufacturers produced simplified surround decoders. To keep the cost down these decoders dispensed with a center speaker output and the logic circuitry found on the professional decoder, but did include the surround delay. To distinguish these decoders from the professional units found in cinemas they were given

528-407: 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

594-471: A non-exclusive basis. In general, motion picture producers elected to license one or the other. In a few cases, where mergers had occurred, a producer might be licensed for both. For many years, it was customary to "brand" a film with its sound system, variously as "RCA Sound Recording", "Western Electric Recording", or similar brands, often including the corporate logo of the licensor ( Meatball for RCA; The Voice of Action for Western Electric; Li Westrex for

660-423: A phantom center and surround is reproduced from both speakers but in a diffuse manner. A simple 4-channel decoder could simply send the sum signal (L+R) to the center speaker, and the difference signal (L-R) to the surrounds. But such a decoder would provide poor separation between adjacent speaker channels, thus anything intended for the center speaker would also reproduce from left and right speakers only 3dB below

726-469: A simple mix of the adjacent channels. Dolby did not approve of this later practice, which results in loss of separation, but instead used these channels for LFE (low-frequency effects) utilizing the bass units of the otherwise redundant intermediate front speakers. Later the unused HF capacity of these channels was used to provide for stereo surround in place of the mono surround of the Todd-AO layout giving

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792-482: A sound version (music plus sound effects only) of the silent film Wings which was exhibited as a road-show in around a dozen specially equipped theatres during 1927. In April 1928, RCA Photophone Inc. was created as a subsidiary of RCA (itself then a GE subsidiary) to commercially exploit the Photophone system. David Sarnoff was president and a member of the board of directors. The RCA system continued to use

858-474: A stereo 2.0 track. The fully degenerate case of stereo variable-area (i.e., no 4-2-4 encoding/decoding, and left total/left equal to right total/right) produces a conventional "dual-bilateral" mono 1.0 track. Once the ability to record stereo tracks became a commercial imperative for sound-transfer facilities, the RCA system was abandoned, as it was incapable of producing time-aligned stereo sound negatives. Whereas

924-460: A time-aligned, two-channel variable-area version, and this then became the industry standard device for recording stereo variable-area optical soundtracks. Variable-density's fate was then sealed as these stereo optical sound prints (as contrasted with stereo magnetic sound prints or mono optical sound prints) became a marketing imperative. When encoded utilizing Dolby Laboratories' technology (itself originally being in part licensed from Sansui ),

990-465: A total of four sound channels, as in the 4-track magnetic system, in the track space formerly allocated for one mono optical channel. Dolby also incorporated its A-Type noise reduction into the Dolby Stereo system. Dolby Labs became involved in movie sound when film studios used Dolby A type noise reduction on studio magnetic film recordings. The first film to use Dolby noise reduction throughout

1056-422: Is carried by both Lt and Rt in phase, and surround channel information by both Lt and Rt but out of phase. This gives good compatibility with both mono playback, which reproduces L, C and R from the mono speaker with C at a level 3dB higher than L or R, but surround information cancels out. It also gives good compatibility with two-channel stereo playback where C is reproduced from both left and right speakers to form

1122-525: Is used as the audio codec for the ATSC standards , though it was standardized as A/52 by the ATSC. It allows the transport of up to five channels of sound with a sixth channel for low-frequency effects (the so-called "5.1" configuration). In contrast, Japanese ISDB HDTV broadcasts use MPEG's Advanced Audio Coding (AAC) as the audio codec, which also allows 5.1 audio output. DVB allows both. MPEG-2 audio

1188-468: Is usually associated with Western Electric and variable-area sound system recording is usually associated with RCA, these relationships are not cast into stone. Both variable-area systems and variable-density systems were marketed by both RCA and Western Electric, the Western Electric light valve being capable of producing either variable-density or variable-area depending on which ribbon axis

1254-463: The CinemaScope system in 1953, the technology had proved to be expensive and unreliable. Except in large cities, most movie theaters did not have facilities for playing back magnetic soundtracks, and a majority of films continued to be produced with mono optical soundtracks. Dolby SVA provided a method for putting high-quality stereo soundtracks on optical sound prints. The optical soundtrack on

1320-740: The DVD specification. Dolby Digital is now found in the HDTV (ATSC) standard of the United States , DVD players , and many satellite-TV and cable-TV receivers. Dolby developed a digital surround sound compression scheme for the TV series The Simpsons . On February 17, 2005, the company became public , offering its shares on the New York Stock Exchange , under the symbol DLB. On March 15, 2005, Dolby celebrated its 40th anniversary at

1386-627: The ShoWest 2005 Festival in San Francisco . On January 8, 2007, Dolby announced the arrival of Dolby Volume at the International Consumer Electronics Show . On June 18, 2010, Dolby introduced Dolby Surround 7.1 , and set up theaters worldwide with 7.1 surround speaker setups to deliver theatrical 7.1 surround sound . The first film to be released with this format was Pixar 's Toy Story 3 which

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1452-576: The galvanometer until the 1970s, when it became technically obsolete. The Western Electric system continued to use the light valve , and, under successor ownership, is still used to this day. For nearly half a century, motion picture sound systems were licensed, with two major licensors in North America, RCA and Western Electric (Northern Electric, in Canada), which licensed their principal sound element (original track negative) recording systems on

1518-562: The 1930s. In particular, the infamous "Academy curve" (the standard frequency response for cinema playback of optical tracks as specified by the Academy of Motion Picture Arts and Sciences in 1938) was still in use. It involved a drastic roll-off in the high-frequency response of the theater system with the intention of reducing the audibility of noise and distortion. Dolby proposed replacing the Academy curve with Dolby A type noise reduction on

1584-634: The MPEG-2 system was rejected. Dolby also offered an incentive for Zenith to switch their vote (which they did); however, it is unknown whether they accepted the offer. RCA Photophone When Joseph P. Kennedy and other investors merged Film Booking Offices of America (FBO) with the Keith-Albee-Orpheum theater chain and Radio Corporation of America ; the resulting movie studio RKO Radio Pictures used RCA Photophone as its primary sound system. In March 1929, RKO released Syncopation ,

1650-489: The Western Electric/Westrex recorders with the ca. 1938 4-ribbon light valve (RA-1231, e.g., but not RA-1231A) were inherently capable of producing time-aligned sound negatives. The Westrex system was renamed Photophone after the Western Electric and Westrex registered trademarks were sold by AT&T and Litton Industries , respectively, to others, for uses other than cinema sound systems. Renaming

1716-448: The Western Electric/Westrex stereo variable-area system, after both the Western Electric and Westrex trademarks became unavailable due to corporate asset sales by the disintegrating Bell System, but the Western Electric/Westrex stereo variable-area system continued to be marketed by a successor, and it is still serviced and supported to this day, although it is no longer branded as Photophone. Although variable-density sound system recording

1782-483: The Westrex system to Photophone was facilitated by the demise of RCA's cinema sound business unit, by the hand of General Electric , RCA's acquirer, and by its failure to protect the Photophone trademark. The Westrex system, briefly renamed Photophone, is still in use, with more than 100 systems currently in active service, world-wide. Some users, including Disney and Warner Bros., have multiple systems. The RCA system

1848-455: The center-channel problem was to use a "directionally enhanced" matrix decoder, based on those developed for domestic " Quadraphonic " systems, to recover a center channel from left and right channels recorded on the film. The matrix decoder originally employed for this used the Sansui QS matrix under license. This system was used for the 1975 Ken Russell film Lisztomania . The matrix

1914-409: 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

1980-495: The discrete L and R channels of Westrex's stereo variable-area system were renamed "Left Total" and "Right Total", and when decoded utilizing Dolby's Cinema Processor these produced the L, C, R and S sound image first commonly used by Fox's CinemaScope magnetic stereo system in 1953. Stereo optical sound prints are compatible with films with any aspect ratio and with normal print film stocks with KS-type film perforations, whereas stereo magnetic sound prints require film stocks with

2046-471: The early 1970s Eastman Kodak revived the idea, as described by R. E. Uhlig in a paper presented to the SMPTE in 1972. Initially using a two-channel 16mm film recorder built for them by RCA , Kodak recorded two-channel stereo soundtracks much as Blumlein and Frayne had done before, but added Dolby noise reduction to improve the limited dynamic range available from these half-width tracks. The remaining problem

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2112-523: The first live-recorded film made with RCA Photophone. In the early years following World War I , Charles A. Hoxie working at General Electric (GE) developed a photographic film recorder, initially to record transoceanic wireless telegraphy signals. However, this recorder was later adapted for recording speech and was used in 1921 to record speeches by President Calvin Coolidge and others which were broadcast over Station WGY (Schenectady). This recorder

2178-421: The former Western Electric (Westrex) system has been renamed Photophone and has become the de facto standard for analogue optical soundtracks, world-wide. The fully implemented case of stereo variable-area (i.e., 4-2-4 encoding/decoding) produces a stereo 3.1 track. The partially degenerate case of stereo variable-area (i.e., no 4-2-4 encoding/decoding, but discrete left total/left and right total/right) produces

2244-427: The highest signal level and gives it priority, attenuating the signals fed to the adjacent channels. Because there already is complete separation between opposite channels there is no need to attenuate those, in effect the decoder switches between L and R priority and C and S priority. This places some limitations on mixing for Dolby Stereo and to ensure that sound mixers mixed soundtracks appropriately they would monitor

2310-571: The left and right tracks that previously caused voice leakage into the surround channel. The Ultra Stereo sound system won a 1984 Technical Achievement Award from the Academy of Motion Picture Arts and Sciences. Dolby Laboratories Dolby Laboratories, Inc. (often shortened to Dolby Labs and known simply as Dolby ) is a British-American technology corporation specializing in audio noise reduction , audio encoding/compression , spatial audio, and HDR imaging. Dolby licenses its technologies to consumer electronics manufacturers. Dolby Labs

2376-463: The level in the center speaker. Similarly anything intended for the left speaker would be reproduced from both the center and surround speakers, again only 3dB below the level in the left speaker. There is, however, complete separation between left and right, and between center and surround channels. To overcome this problem the cinema decoder uses so-called "logic" circuitry to improve the separation. The logic circuitry decides which speaker channel has

2442-402: The modern 5.1 channel allocation retained by Dolby Digital . By 1984, Dolby Stereo had a competitor. Ultra Stereo Labs had introduced a comparable stereo optical sound system, Ultra Stereo . Its cinema processor introduced improvements in matrix decoding and convolution matching with greater channel separation. An included balancing circuit compensated for film weave and some imbalances between

2508-428: 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

2574-414: The music industry. In May 2020, Dolby launched a developer platform, Dolby.io , aimed at providing developers self-service access to Dolby technologies through public APIs. It allows any person, organization, small and big, to integrate in their websites, apps, games, etc. features such as media enhancements and transcoding, spatial audio, high-quality video communication and low-latency streaming. Over

2640-460: The name "Dolby Surround" decoders. The term "Dolby Surround" was also licensed by Dolby for use on TV programs or straight-to-video movies recorded through the Dolby Stereo matrix. By the late 1980s integrated-circuit manufacturers were working on designing Dolby matrix decoders. A typical early example is the SSM-2125 from PMI. The SSM-2125 is a complete Dolby Stereo matrix decoder (except for

2706-646: The narrower CS-type film perforations. Film with CS-type perforations can only be run on a projector fitted with special narrow-toothed sprockets or permanent damage will be done to the film. An alternative is LaVezzi's VKF ("Very Kind to Film") sprockets, which perform optimally on KS- as well as CS-perforated prints. Stereo variable-area, therefore, provided for the first time stereo film prints of any aspect ratio (1.37:1/Academy through 2.35:1/CinemaScope, inclusive) which could be run without damage on any normal 35mm cinema projector. Nearly all original track negatives (OTNs) are now produced as stereo variable-area, and

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2772-423: The other system/manufacturer. Variable-density was preferred for Technicolor sound prints as this process utilized a silver gray-scale "key" record, thereby creating a CMYK color image, and the soundtrack was also a silver gray-scale record, which greatly facilitated variable-density (and made variable-area rather difficult). The "key" record was deleted from most Technicolor prints after 1944, thereby creating

2838-437: The post-1956 divestiture of Western Electric under Litton Industries' ownership). Such branding ceased in about 1976, particularly after nearly all optical sound recording (for release prints) had been converted to Westrex's stereo variable-area system from RCA's and Westrex's mono systems, although there were a few examples of such branding thereafter (mainly Westrex.) Many years later, the Photophone trademark would be reused by

2904-411: The production process is A Clockwork Orange (1971), though much of the benefit was lost when it was released with a standard "Academy" optical soundtrack. This led to a proposal from Dolby that A type noise reduction be applied to the optical soundtrack on release prints. Through the early 1970s, there was renewed interest in improving the quality of optical soundtracks, which had changed little since

2970-421: The sound mix via a Dolby Stereo encoder and decoder in tandem. In addition to the logic circuitry the surround channel is also fed via a delay, adjustable up to 100 ms to suit auditoria of differing sizes, to ensure that any leakage of program material intended for left or right speakers into the surround channel is always heard first from the intended speaker. This exploits the " Precedence effect " to localize

3036-513: The sound to the intended direction. Dolby Surround is the earliest consumer version of Dolby's multichannel analog film sound format Dolby Stereo. Due to the compatibility of the Dolby Stereo matrix with mono and stereo playback, when films originally made in Dolby Stereo were released on stereo domestic video formats - such as VHS-HiFi, laserdisc or broadcast on stereo TV - the original two-channel Dolby Stereo soundtrack could be used. Some domestic listeners were keen to hear these soundtracks in

3102-503: The successor to Western Electric's cinema sound business unit) re-introduced the ca. 1938 "four ribbon" light valve, and the ca. 1947 RA-1231 sound recorder. When originally introduced in 1947, the RA-1231 could be configured as a mono 35mm variable-density or variable-area recorder, or a mono 16mm variable-density or variable-area recorder, at the customer's option. However its basic electro-optical arrangement could also be used to create

3168-495: The surround delay) on a single chip, it allowed domestic decoders which used the same logic system found in professional decoders to be marketed to the consumer. These decoders were thus named Dolby Pro Logic . Dolby Stereo 70 mm Six Track is the use of Dolby noise reduction on the six magnetic soundtracks of a 70 mm print. This was first used on some prints of the MGM film Logan's Run released in 1976. The Todd-AO format

3234-440: The technology on disc was Game of Thrones . On February 24, 2014, Dolby acquired Doremi Labs for $ 92.5 million in cash plus an additional $ 20 million in contingent consideration that may be earned over a four-year period. In May 2015, Dolby reopened Vine Theatre as a 70-seat showcase theater, known as Dolby @ Vine or Dolby Screening Room Hollywood Vine. In May 2019, Dolby added Dolby Atmos to hundreds of newer songs in

3300-512: The technology until stereo was added to the mix. The idea of putting a two-channel optical stereo soundtrack in the normal soundtrack area of a film print was not new; the stereo pioneer Alan Blumlein had made experimental stereophonic films using such a system as early as 1933, and J. G. Frayne of Westrex had proposed a similar system to the SMPTE in 1955. By 1970, however, it was apparent that magnetic recording methods were not going to displace optical soundtracks on most release prints, and in

3366-421: The track. Starting with the 1974 film Callan , ten films were released with a Dolby encoded mono soundtrack. Theaters were equipped with a Dolby A type noise reduction module and a third-octave equalizer to equalize the electro-acoustic frequency response of the speakers/auditorium. It created a new international standard for cinema sound. Though the system worked well, theater owners were reluctant to invest in

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3432-494: The years Dolby has introduced several surround sound systems. Their differences are explained below. Matrix decoding can derive Cs (mono surround) or Lrs, Rrs (stereo surrounds) from the Ls and Rs signals L, R, C, LFE, Lss, Rss (side surrounds), Lrs, Rrs (rear surrounds), Lts, Rts (top surrounds). Note: the number and intended location of _output_ channels is defined at playback based on the available loudspeakers. Dolby Digital AC-3

3498-441: Was A Clockwork Orange (1971). The company was approached by Stanley Kubrick, who wanted to use Dolby’s noise reduction system to facilitate the film’s extensive mixing. The film went on to use Dolby noise reduction on all pre-mixes and masters, but a conventional optical soundtrack on release prints. Callan (1974) was the first film with a Dolby-encoded optical soundtrack. In 1975, Dolby released Dolby Stereo , which included

3564-453: Was a contender for the ATSC standard during the " Grand Alliance " shootout, but lost out to Dolby AC-3 . The Grand Alliance issued a statement finding the MPEG-2 system to be "essentially equivalent" to Dolby, but only after the Dolby selection had been made. Later, a story emerged that MIT had entered into an agreement with Dolby whereupon the university would be awarded a large sum of money if

3630-571: Was adapted for home use as Dolby Surround when hi-fi capable consumer VCRs were introduced, and further improved in 1987 with the Dolby Pro Logic home decoding system . Of the two, Dolby SVA is by far the more significant, bringing high-quality stereo sound within the reach of virtually every cinema. Though 6-track magnetic stereo had been used in Cinerama films since 1952, and Fox had introduced 4-track stereo magnetic sound as part of

3696-728: Was called the Pallophotophone . In 1925, GE began a program to develop commercial sound-on-film equipment based on Hoxie's work. Unlike the Phonofilm and Movietone systems in which the audio modulated the intensity of a recording lamp which exposed the soundtrack, thus creating a variable-density track, the GE system employed a fast-acting mirror galvanometer to create a variable-area soundtrack. A number of demonstrations of this system, now known as Photophone, were given in 1926 and 1927. The first public screenings with this system were of

3762-417: Was first used in that year's Hair and Hurricane . At first, Dolby Stereo equipment was installed mainly in larger theaters already equipped with amplifiers and speakers for CinemaScope 4-track stereo. But the success of 1977's Star Wars , which used the 4-channel system to great effect, encouraged owners of smaller theaters to install stereo equipment for the first time. A key feature of this system

3828-628: Was founded by Ray Dolby (1933–2013) in London , England, in 1965. In the same year, he invented the Dolby Noise Reduction system , a form of audio signal processing for reducing the background hissing sound on cassette tape recordings. His first U.S. patent on the technology was filed in 1969, four years later. The method was first used by Decca Records in the UK. After this, other companies began purchasing Dolby’s A301 technology, which

3894-451: Was introduced in 1955 and included multi-channel magnetic sound from the start, it does not have an optical soundtrack, although in some 70mm prints have used a DTS digital track in place of the analogue magnetic one. The original layout was for 5 front channels and one surround. But by the 1970s the use of the intermediate (left-center and right-center) tracks had been largely abandoned, these channels either being left blank, or filled with

3960-553: Was its backward compatibility : the same print could play anywhere, from an old drive-in theater with mono sound to a Dolby Stereo-equipped cinema, eliminating the need for a costly double inventory of prints for distribution. The success of Dolby Stereo resulted in the final demise of magnetic stereo on 35mm release prints. From then on, only 70mm prints used magnetic sound. In the early 1990s, Dolby SR noise reduction began to replace Dolby A type NR in 35mm motion picture exhibition. All release prints encoded with Dolby Digital include

4026-515: Was later followed by fifty releases using the format. About 80% of films released are now mixed in Dolby Surround 7.1 by default. In April 2012, Dolby introduced its Dolby Atmos , a new cinematic technology adding overhead sound, first applied in Pixar's motion picture Brave . In July 2014, Dolby Laboratories announced plans to bring Atmos to home theater. The first television show to use

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4092-476: Was parallel to the film motion, and the RCA galvanometer was capable of producing either variable-area or variable-density depending upon the particulars of the optical system. Roughly equal measured and perceived quality was available from both systems and from both manufacturers. Neither recording system nor manufacturer was clearly superior to the other, except where specific customer end-to-end processes made one system/manufacturer more consistently superior to

4158-484: Was renewed interest in improving the quality of optical film soundtracks. As a consequence by the early 1970s several individuals and organizations were considering improvements to the dated technical standards used for optical sound on 35mm film. In particular both Dolby Laboratories and Kodak were investigating the use of Dolby noise reduction on optical soundtracks . In the mid-1970s, Westrex Corp. (a wholly owned subsidiary of Litton Industries since 1956, and

4224-424: Was the lack of a center channel, regarded as essential to lock dialogue to the middle of the screen. Uhlig discussed this issue in a follow-up paper. He considered the possibility of splitting the soundtrack area three ways to provide a third center channel, but dismissed it because of the negative impact it would have on dynamic range and the problems involved in converting film projectors. Instead he suggested feeding

4290-412: Was the professional noise reduction system used in recording, motion picture, broadcasting stations and communications networks. These companies include BBC , Pye , IBC, CBS Studios, RCA, and Granada. He moved the company headquarters to the United States ( San Francisco , California) in 1976. The first product Dolby Labs produced was the Dolby 301 unit which incorporated Type A Dolby Noise Reduction,

4356-463: Was then extended to provide a fourth channel for surround loudspeakers, allowing for a 4-channel system with the same speaker layout as the CinemaScope 4-track magnetic stereo system of the 1950s, but at a far lower cost. Dolby Stereo, as this 4-channel system was now branded, was first used in 1976's A Star is Born . From spring 1979 onward, a new custom matrix replaced the Sansui QS matrix. It

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