Dolby SR



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 audio noise reduction, audio encoding/compression, spatial audio, and HDR imaging. Dolby licenses its technologies t ...
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 companders) 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- ...
(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 engineers, broadcasters, and other audio professionals. It is used as the optical analog format on almost all 35mm film 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.


See also

Dolby noise-reduction system A Dolby noise-reduction system, or Dolby NR, is one of a series of noise reduction systems developed by Dolby Laboratories for use in analog audio tape recording. The first was '' Dolby A'', a professional broadband noise reduction s ...
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 {{film-tech-stub de:Dolby#Dolby SR