The Dolby SR (Spectral Recording) noise reduction format was developed by
Dolby Laboratories
Dolby Laboratories, Inc. (often shortened to Dolby Labs and known simply as Dolby) is an American company specializing in Noise reduction#In audio, audio noise reduction, Audio data compression, audio encoding/compression, spatial audio, and ...
and has been in common use in professional audio since 1986 and in cinema audio since the late 1980s.
It is a revised version of Dolby's earlier formats, combining aspects of
Dolby A, B and C (e.g., sliding band and fixed band
compander
In telecommunication and signal processing, companding (occasionally called compansion) is a method of mitigating the detrimental effects of a channel with limited dynamic range. The name is a portmanteau of the words compressing and expanding, ...
s) to improve the
dynamic range
Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-1 ...
(i.e., the range in decibels between peak level and noise floor) of analogue recordings and transmissions by as much as 25
dB.
Dolby SR is used in many modern professional audio analogue (i.e., tape) recordings by recording and
postproduction
Post-production is part of the process of filmmaking, video production, audio production, and photography. Post-production includes all stages of production occurring after principal photography or recording individual program segments.
The ...
engineers, broadcasters, and other audio professionals. It is used as the optical analog format on almost all
35mm film 35 mm may refer to:
* 135 film, a type of still photography format commonly referred to as 35 mm film
* 35 mm movie film, a type of motion picture film stock
* 35MM 35 mm may refer to:
* 135 film, a type of still photography format ...
release prints, and is always the accompanying optical analog format when Dolby Digital is present.
Dolby SR was originally implemented in Dolby's Cat. 280 card, which was pin-compatible with the Cat. 22 A-type noise reduction card. Thus, devices that took the Cat. 22 card could be upgraded from A to SR by replacing the Cat. 22 with the Cat. 280. The Cat. 280 card functions in many devices including Dolby's Model 361 frame. Some Dolby Cinema processors require a special version, the Cat. 280T, which functions for decoding (playback) only.
References
See also
*
Dolby noise-reduction system
A Dolby noise-reduction system, or Dolby NR, is one of a series of Audio noise reduction, noise reduction systems developed by Dolby Laboratories for use in analog audio tape recording. The first was ''#Dolby A, Dolby A'', a professio ...
*
Dolby Surround
Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround.
Dolby Stereo (also known as ''Dolby MP'' or ''Dolby SVA'') was developed by Dolby in 1976 f ...
*
Dolby Digital
Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995, the audio compression is lossy ...
Noise reduction systems
Dolby Laboratories
Audiovisual introductions in 1986
American brands
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