Dolby Digital
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| Abbreviation | DD |
|---|---|
| Formation | 1986 |
| Type | Audio compression format, lossy compression |
| Location |
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Area served | Worldwide |
| Website | professional |
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. Originally named Dolby Stereo Digital until 1995, except for Dolby TrueHD, the audio compression is lossy, based on the modified discrete cosine transform (MDCT) algorithm. The first use of Dolby Digital was to provide digital sound in cinemas from 35 mm film prints; today, it is now also used for applications such as TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles.
The main basis of the Dolby AC-3 multi-channel audio coding standard is the modified discrete cosine transform (MDCT), a lossy audio compression algorithm.[1] It is a modification of the discrete cosine transform (DCT) algorithm, which was first proposed by Nasir Ahmed in 1972 and was originally intended for image compression.[2] The DCT was adapted into the modified discrete cosine transform (MDCT) by J.P. Princen, A.W. Johnson and Alan B. Bradley at the University of Surrey in 1987.[3]
Dolby Laboratories adapted the MDCT algorithm along with perceptual coding principles to develop the AC-3 audio format for cinema needs. The AC-3 format was released as the Dolby Digital standard in 1991.[4] Dolby Digital was the earliest MDCT-based audio compression standard to be released, and was followed by other MDCT-based audio compression standards for home and portable usage, such as Sony's ATRAC (1992), the MP3 standard (1993) and AAC (1997).[5]
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- ↑ Andersen, Robert Loring; Crockett, Brett Graham; Davidson, Grant A.; Davis, Mark Franklin; Fielder, Louis D.; Turner, Stephen C.; Vinton, Mark S.; Williams, Phillip (October 2004). "Introduction to Dolby Digital Plus, an Enhancement to the Dolby Digital Coding System" (PDF). Audio Engineering Society Convention (117th AES Convention): 1–29. Retrieved 17 October 2019.
- ↑ Ahmed, Nasir (January 1991). "How I Came Up With the Discrete Cosine Transform". Digital Signal Processing. 1 (1): 4–5. doi:10.1016/1051-2004(91)90086-Z.
- ↑ Princen, J.P.; Johnson, A.W.; Bradley, Alan B. (1987). "Subband/Transform coding using filter bank designs based on time domain aliasing cancellation". ICASSP '87. IEEE International Conference on Acoustics, Speech, and Signal Processing. 12: 2161–2164. doi:10.1109/ICASSP.1987.1169405. Unknown parameter
|s2cid=ignored (help) - ↑ Britanak, V. (2011). "On Properties, Relations, and Simplified Implementation of Filter Banks in the Dolby Digital (Plus) AC-3 Audio Coding Standards". IEEE Transactions on Audio, Speech, and Language Processing. 19 (5): 1231–1241. doi:10.1109/TASL.2010.2087755. Unknown parameter
|s2cid=ignored (help) - ↑ Luo, Fa-Long (2008). Mobile Multimedia Broadcasting Standards: Technology and Practice. Springer Science & Business Media. p. 590. ISBN 9780387782638. Search this book on
