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Media Licensing
In 1970 Dolby began to promote the idea of releasing prerecorded cassettes encoded with the Dolby B-type® characteristic, so that they would have low noise when played on players equipped with Dolby B-type noise reduction. Listening tests performed by several record companies, notably Decca in the UK and Ampex Stereo Tapes in the US, showed that Dolby B encoded tapes were even preferred over non-encoded tapes when played on players without noise reduction, eliminating the need to release cassettes in both encoded and unencoded forms. Later that year, these companies issued their first B-type encoded tapes, using professional-quality B-type encoders manufactured by Dolby Laboratories. (Dolby has continued to supply the recording industry with encoders embodying its technology, thereby ensuring proper playback on the licensed consumer products that meet its quality standards).
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Within a few years, virtually all prerecorded cassettes would be encoded with Dolby B-type NR, which remains true today. Indeed, the Dolby B encoded cassette was to become the most popular carrier of recorded music the world had ever seen, eventually surpassing LP record sales, and itself surpassed only by the CD in the early 1990s.
Dolby developed a trademark and quality-control license for record companies to use the Dolby trademarks on prerecorded tapes. To help establish Dolby B as the standard consumer tape noise reduction system and to promote sales of Dolby B equipped cassette recorders, the license was made royalty-free. This policy has remained in effect for all media recorded with Dolby technologies, which today encompasses not only virtually all audio cassette releases, but also thousands of videocassette, laser disc, video game, and DVD releases encoded with Dolby Surround and/or Dolby Digital.
Dolby Licensing Today
Dolby's licensing effort is administered by a large staff of engineers, technicians, and intellectual property specialists at the company's San Francisco headquarters. Dolby's comprehensive licensing program includes testing hundreds of product and software samples, regularly visiting consumer electronics factories and design centers worldwide, and assisting IC manufacturers in implementing Dolby technologies as integrated circuits for inclusion in consumer products.
In addition to analog noise reduction and home theater surround sound technology, licensed technologies today include many digital technologies, such as Dolby Digital, the multichannel digital surround sound format adopted for use with DVD, digital broadcast TV, digital cable, and direct satellite broadcast (DSB).
Dolby Investigates Film Sound
In the late 1960s, even as B-type noise reduction was coming to market, Dolby began to seek out additional applications for its noise reduction technology. One area that looked promising was film sound, in particular, the photographic or "optical" soundtrack, introduced in the late 1920s and, thanks in great part to Dolby's efforts, still by far the most popular kind of film soundtrack.
The optical soundtrack has many advantages, including economy, reliability, and relatively long print life. Equally as important, 35 mm film with optical sound is a truly universal medium: A film made in the US, for example, can play in theatres the world over. This universality, however, has its downside.
To forestall compatibility problems after a decade of theatres racing to install sound equipment and filmmakers rushing "talkies" into production, in the late 1930s the film industry adopted a standardized theatre playback response that today is called the "Academy" characteristic. While this resulted in a system of recording and playback that made it possible for just about any film to sound acceptable in any theatre in the world, it lacked the flexibility to incorporate improvements beyond the limitations of the 1930s. Indeed, well into the 1970s conventional optical sound reproduction in the theatre had a frequency response little wider than a telephone's.
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 (the "Academy" characteristic). 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.
Off to a Slow Start
Dolby conjectured that applying Dolby A-type noise reduction to the optical soundtrack would enable wider frequency response in the theatre, and also permit mixers to record "flatter," less distorted soundtracks. The theoretical result—significantly higher fidelity optical sound—subsequently proved to be true. |
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Dolby went on to develop an A-type noise reduction unit specifically for use in movie theatres, which incorporated a special equalizer to widen the response of theatre speakers already in place. The compatibility of movie prints with A-type encoded soundtracks heard in theatres without a Dolby decoder was tested and judged acceptable, much as B-type encoded cassettes were being accepted as compatible. Thus, when lobbying the film industry to produce encoded films, Dolby could argue that only one type of release print would be needed for all theatres.
This first film sound attempt met with only modest success, however. While the improvement in fidelity was unquestionable, optical sound was still mono. By this time, superior hi-fi stereo systems had been installed in so many homes that a significant proportion of the movie-going public was used to better sound at home than could be heard in the theatre. And since the 1950s, the movie industry had had at its disposal a different soundtrack method that provided multichannel stereo sound.
This alternative method involves applying narrow stripes of iron oxide material (similar to the coating on magnetic recording tape) to the finished release print. The sound is then recorded on the magnetic stripes in real time. The film is played back on projectors equipped with magnetic heads similar to those on a tape recorder.
Many theatres had been equipped for magnetic sound in the 1950s. However, by the 1970s, the expense of magnetic release prints (more than ten times that of optical prints), their comparatively short life (compared to optical prints), and the high cost of maintaining magnetic playback heads led to a massive reduction in the number of magnetic releases and theatres capable of playing them. Magnetic stereo sound came to be reserved for a only handful of first-run engagements of blockbuster releases each year. By the time Dolby came on the scene, moviegoers were again usually hearing low fidelity, mono optical releases, with only an occasional multitrack stereo magnetic release.
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