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Audio coding format

August 22, 2023

An audio coding format[1] (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus. A specific software or hardware implementation capable of audio compression and decompression to/from a specific audio coding format is called an audio codec; an example of an audio codec is LAME, which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software.

Comparison of coding efficiency between popular audio formats

Some audio coding formats are documented by a detailed technical specification document known as an audio coding specification. Some such specifications are written and approved by standardization organizations as technical standards, and are thus known as an audio coding standard. The term "standard" is also sometimes used for de facto standards as well as formal standards.

Audio content encoded in a particular audio coding format is normally encapsulated within a container format. As such, the user normally doesn't have a raw AAC file, but instead has a .m4a audio file, which is a MPEG-4 Part 14 container containing AAC-encoded audio. The container also contains metadata such as title and other tags, and perhaps an index for fast seeking.[2] A notable exception is MP3 files, which are raw audio coding without a container format. De facto standards for adding metadata tags such as title and artist to MP3s, such as ID3, are hacks which work by appending the tags to the MP3, and then relying on the MP3 player to recognize the chunk as malformed audio coding and therefore skip it. In video files with audio, the encoded audio content is bundled with video (in a video coding format) inside a multimedia container format.

An audio coding format does not dictate all algorithms used by a codec implementing the format. An important part of how lossy audio compression works is by removing data in ways humans can't hear, according to a psychoacoustic model; the implementer of an encoder has some freedom of choice in which data to remove (according to their psychoacoustic model).

Lossless, lossy, and uncompressed audio coding formats

A lossless audio coding format reduces the total data needed to represent a sound but can be de-coded to its original, uncompressed form. A lossy audio coding format additionally reduces the bit resolution of the sound on top of compression, which results in far less data at the cost of irretrievably lost information.

Consumer audio is most often compressed using lossy audio codecs as the smaller size is far more convenient for distribution. The most widely used audio coding formats are MP3 and Advanced Audio Coding (AAC), both of which are lossy formats based on modified discrete cosine transform (MDCT) and perceptual coding algorithms.

Lossless audio coding formats such as FLAC and Apple Lossless are sometimes available, though at the cost of larger files.

Uncompressed audio formats, such as pulse-code modulation (PCM, or .wav), are also sometimes used. PCM was the standard format for Compact Disc Digital Audio (CDDA), before lossy compression eventually became the standard after the introduction of MP3.

History

 
Solidyne 922: The world's first commercial audio bit compression sound card for PC, 1990

In 1950, Bell Labs filed the patent on differential pulse-code modulation (DPCM).[3] Adaptive DPCM (ADPCM) was introduced by P. Cummiskey, Nikil S. Jayant and James L. Flanagan at Bell Labs in 1973.[4][5]

Perceptual coding was first used for speech coding compression, with linear predictive coding (LPC).[6] Initial concepts for LPC date back to the work of Fumitada Itakura (Nagoya University) and Shuzo Saito (Nippon Telegraph and Telephone) in 1966.[7] During the 1970s, Bishnu S. Atal and Manfred R. Schroeder at Bell Labs developed a form of LPC called adaptive predictive coding (APC), a perceptual coding algorithm that exploited the masking properties of the human ear, followed in the early 1980s with the code-excited linear prediction (CELP) algorithm which achieved a significant compression ratio for its time.[6] Perceptual coding is used by modern audio compression formats such as MP3[6] and AAC.

Discrete cosine transform (DCT), developed by Nasir Ahmed, T. Natarajan and K. R. Rao in 1974,[8] provided the basis for the modified discrete cosine transform (MDCT) used by modern audio compression formats such as MP3[9] and AAC. MDCT was proposed by J. P. Princen, A. W. Johnson and A. B. Bradley in 1987,[10] following earlier work by Princen and Bradley in 1986.[11] The MDCT is used by modern audio compression formats such as Dolby Digital,[12][13] MP3,[9] and Advanced Audio Coding (AAC).[14]

List of lossy formats

General

Basic compression algorithm Audio coding standard Abbreviation Introduction Market share (2019)[15] Ref
Modified discrete cosine transform (MDCT) Dolby Digital (AC-3) AC3 1991 58% [12][16]
Adaptive Transform Acoustic Coding ATRAC 1992 Un­known [12]
MPEG Layer III MP3 1993 49% [9][17]
Advanced Audio Coding (MPEG-2 / MPEG-4) AAC 1997 88% [14][12]
Windows Media Audio WMA 1999 Un­known [12]
Ogg Vorbis Ogg 2000 7% [18][12]
Constrained Energy Lapped Transform CELT 2011 — [19]
Opus Opus 2012 8% [20]
LDAC LDAC 2015 Un­known [21][22]
Adaptive differential pulse-code modulation (ADPCM) aptX / aptX-HD aptX 1989 Un­known [23]
Digital Theater Systems DTS 1990 14% [24][25]
Master Quality Authenticated MQA 2014 Un­known
Sub-band coding (SBC) MPEG-1 Audio Layer II MP2 1993 Un­known
Musepack MPC 1997

Speech

Further information: Speech coding

List of lossless formats

See also

References

  1. ^ The term "audio coding" can be seen in e.g. the name Advanced Audio Coding, and is analogous to the term video coding
  2. ^ "Video - Where is synchronization information stored in container formats?".
  3. ^ US patent 2605361, C. Chapin Cutler, "Differential Quantization of Communication Signals", issued 1952-07-29 
  4. ^ Cummiskey, P.; Jayant, N. S.; Flanagan, J. L. (1973). "Adaptive Quantization in Differential PCM Coding of Speech". Bell System Technical Journal. 52 (7): 1105–1118. doi:10.1002/j.1538-7305.1973.tb02007.x.
  5. ^ Cummiskey, P.; Jayant, Nikil S.; Flanagan, J. L. (1973). "Adaptive quantization in differential PCM coding of speech". The Bell System Technical Journal. 52 (7): 1105–1118. doi:10.1002/j.1538-7305.1973.tb02007.x. ISSN 0005-8580.
  6. ^ a b c Schroeder, Manfred R. (2014). "Bell Laboratories". Acoustics, Information, and Communication: Memorial Volume in Honor of Manfred R. Schroeder. Springer. p. 388. ISBN 9783319056609.
  7. ^ Gray, Robert M. (2010). "A History of Realtime Digital Speech on Packet Networks: Part II of Linear Predictive Coding and the Internet Protocol" (PDF). Found. Trends Signal Process. 3 (4): 203–303. doi:10.1561/2000000036. ISSN 1932-8346.
  8. ^ Nasir Ahmed; T. Natarajan; Kamisetty Ramamohan Rao (January 1974). "Discrete Cosine Transform" (PDF). IEEE Transactions on Computers. C-23 (1): 90–93. doi:10.1109/T-C.1974.223784. S2CID 149806273.
  9. ^ a b c Guckert, John (Spring 2012). "The Use of FFT and MDCT in MP3 Audio Compression" (PDF). University of Utah. Retrieved 14 July 2019.
  10. ^ Princen, J.; Johnson, A.; Bradley, A. (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. Vol. 12. pp. 2161–2164. doi:10.1109/ICASSP.1987.1169405. S2CID 58446992.
  11. ^ Princen, J.; Bradley, A. (1986). "Analysis/Synthesis filter bank design based on time domain aliasing cancellation". IEEE Transactions on Acoustics, Speech, and Signal Processing. 34 (5): 1153–1161. doi:10.1109/TASSP.1986.1164954.
  12. ^ a b c d e f Luo, Fa-Long (2008). Mobile Multimedia Broadcasting Standards: Technology and Practice. Springer Science & Business Media. p. 590. ISBN 9780387782638.
  13. ^ 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. S2CID 897622.
  14. ^ a b Brandenburg, Karlheinz (1999). "MP3 and AAC Explained" (PDF). (PDF) from the original on 2017-02-13.
  15. ^ "Video Developer Report 2019" (PDF). Bitmovin. 2019. Retrieved 5 November 2019.
  16. ^ 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. S2CID 897622.
  17. ^ Stanković, Radomir S.; Astola, Jaakko T. (2012). "Reminiscences of the Early Work in DCT: Interview with K.R. Rao" (PDF). Reprints from the Early Days of Information Sciences. 60. Retrieved 13 October 2019.
  18. ^ Xiph.Org Foundation (2009-06-02). "Vorbis I specification - 1.1.2 Classification". Xiph.Org Foundation. Retrieved 2009-09-22.
  19. ^ Terriberry, Timothy B. Presentation of the CELT codec. Presentation (PDF).
  20. ^ Valin, Jean-Marc; Maxwell, Gregory; Terriberry, Timothy B.; Vos, Koen (October 2013). High-Quality, Low-Delay Music Coding in the Opus Codec. 135th AES Convention. Audio Engineering Society. arXiv:1602.04845.
  21. ^ Darko, John H. (2017-03-29). . DAR__KO. Archived from the original on 2018-01-14. Retrieved 2018-01-13.
  22. ^ Ford, Jez (2015-08-24). "What is Sony LDAC, and how does it do it?". AVHub. Retrieved 2018-01-13.
  23. ^ Ford, Jez (2016-11-22). "aptX HD - lossless or lossy?". AVHub. Retrieved 2018-01-13.
  24. ^ "Digital Theater Systems Audio Formats". Library of Congress. 27 December 2011. Retrieved 10 November 2019.
  25. ^ Spanias, Andreas; Painter, Ted; Atti, Venkatraman (2006). Audio Signal Processing and Coding. John Wiley & Sons. p. 338. ISBN 9780470041963.

August 22, 2023
audio, coding, format, audio, coding, format, sometimes, audio, compression, format, content, representation, format, storage, transmission, digital, audio, such, digital, television, digital, radio, audio, video, files, examples, audio, coding, formats, inclu. An audio coding format 1 or sometimes audio compression format is a content representation format for storage or transmission of digital audio such as in digital television digital radio and in audio and video files Examples of audio coding formats include MP3 AAC Vorbis FLAC and Opus A specific software or hardware implementation capable of audio compression and decompression to from a specific audio coding format is called an audio codec an example of an audio codec is LAME which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software Comparison of coding efficiency between popular audio formatsSome audio coding formats are documented by a detailed technical specification document known as an audio coding specification Some such specifications are written and approved by standardization organizations as technical standards and are thus known as an audio coding standard The term standard is also sometimes used for de facto standards as well as formal standards Audio content encoded in a particular audio coding format is normally encapsulated within a container format As such the user normally doesn t have a raw AAC file but instead has a m4a audio file which is a MPEG 4 Part 14 container containing AAC encoded audio The container also contains metadata such as title and other tags and perhaps an index for fast seeking 2 A notable exception is MP3 files which are raw audio coding without a container format De facto standards for adding metadata tags such as title and artist to MP3s such as ID3 are hacks which work by appending the tags to the MP3 and then relying on the MP3 player to recognize the chunk as malformed audio coding and therefore skip it In video files with audio the encoded audio content is bundled with video in a video coding format inside a multimedia container format An audio coding format does not dictate all algorithms used by a codec implementing the format An important part of how lossy audio compression works is by removing data in ways humans can t hear according to a psychoacoustic model the implementer of an encoder has some freedom of choice in which data to remove according to their psychoacoustic model Contents 1 Lossless lossy and uncompressed audio coding formats 2 History 3 List of lossy formats 3 1 General 3 2 Speech 4 List of lossless formats 5 See also 6 ReferencesLossless lossy and uncompressed audio coding formats EditA lossless audio coding format reduces the total data needed to represent a sound but can be de coded to its original uncompressed form A lossy audio coding format additionally reduces the bit resolution of the sound on top of compression which results in far less data at the cost of irretrievably lost information Consumer audio is most often compressed using lossy audio codecs as the smaller size is far more convenient for distribution The most widely used audio coding formats are MP3 and Advanced Audio Coding AAC both of which are lossy formats based on modified discrete cosine transform MDCT and perceptual coding algorithms Lossless audio coding formats such as FLAC and Apple Lossless are sometimes available though at the cost of larger files Uncompressed audio formats such as pulse code modulation PCM or wav are also sometimes used PCM was the standard format for Compact Disc Digital Audio CDDA before lossy compression eventually became the standard after the introduction of MP3 History Edit Solidyne 922 The world s first commercial audio bit compression sound card for PC 1990In 1950 Bell Labs filed the patent on differential pulse code modulation DPCM 3 Adaptive DPCM ADPCM was introduced by P Cummiskey Nikil S Jayant and James L Flanagan at Bell Labs in 1973 4 5 Perceptual coding was first used for speech coding compression with linear predictive coding LPC 6 Initial concepts for LPC date back to the work of Fumitada Itakura Nagoya University and Shuzo Saito Nippon Telegraph and Telephone in 1966 7 During the 1970s Bishnu S Atal and Manfred R Schroeder at Bell Labs developed a form of LPC called adaptive predictive coding APC a perceptual coding algorithm that exploited the masking properties of the human ear followed in the early 1980s with the code excited linear prediction CELP algorithm which achieved a significant compression ratio for its time 6 Perceptual coding is used by modern audio compression formats such as MP3 6 and AAC Discrete cosine transform DCT developed by Nasir Ahmed T Natarajan and K R Rao in 1974 8 provided the basis for the modified discrete cosine transform MDCT used by modern audio compression formats such as MP3 9 and AAC MDCT was proposed by J P Princen A W Johnson and A B Bradley in 1987 10 following earlier work by Princen and Bradley in 1986 11 The MDCT is used by modern audio compression formats such as Dolby Digital 12 13 MP3 9 and Advanced Audio Coding AAC 14 List of lossy formats EditGeneral Edit Basic compression algorithm Audio coding standard Abbreviation Introduction Market share 2019 15 RefModified discrete cosine transform MDCT Dolby Digital AC 3 AC3 1991 58 12 16 Adaptive Transform Acoustic Coding ATRAC 1992 Un known 12 MPEG Layer III MP3 1993 49 9 17 Advanced Audio Coding MPEG 2 MPEG 4 AAC 1997 88 14 12 Windows Media Audio WMA 1999 Un known 12 Ogg Vorbis Ogg 2000 7 18 12 Constrained Energy Lapped Transform CELT 2011 19 Opus Opus 2012 8 20 LDAC LDAC 2015 Un known 21 22 Adaptive differential pulse code modulation ADPCM aptX aptX HD aptX 1989 Un known 23 Digital Theater Systems DTS 1990 14 24 25 Master Quality Authenticated MQA 2014 Un knownSub band coding SBC MPEG 1 Audio Layer II MP2 1993 Un knownMusepack MPC 1997Speech Edit Further information Speech coding Linear predictive coding LPC Adaptive predictive coding APC Code excited linear prediction CELP Algebraic code excited linear prediction ACELP Relaxed code excited linear prediction RCELP Low delay CELP LD CELP Adaptive Multi Rate used in GSM and 3GPP Codec2 noted for its lack of patent restrictions Speex noted for its lack of patent restrictions Modified discrete cosine transform MDCT AAC LD Constrained Energy Lapped Transform CELT Opus mostly for real time applications List of lossless formats EditApple Lossless ALAC Apple Lossless Audio Codec Adaptive Transform Acoustic Coding ATRAC Audio Lossless Coding also known as MPEG 4 ALS Direct Stream Transfer DST Dolby TrueHD DTS HD Master Audio Free Lossless Audio Codec FLAC Lossless discrete cosine transform LDCT Meridian Lossless Packing MLP Monkey s Audio Monkey s Audio APE MPEG 4 SLS also known as HD AAC OptimFROG Original Sound Quality OSQ RealPlayer RealAudio Lossless Shorten SHN TTA True Audio Lossless WavPack WavPack lossless WMA Lossless Windows Media Lossless See also EditComparison of audio coding formats Data compression Audio Audio file format List of audio compression formatsReferences Edit The term audio coding can be seen in e g the name Advanced Audio Coding and is analogous to the term video coding Video Where is synchronization information stored in container formats US patent 2605361 C Chapin Cutler Differential Quantization of Communication Signals issued 1952 07 29 Cummiskey P Jayant N S Flanagan J L 1973 Adaptive Quantization in Differential PCM Coding of Speech Bell System Technical Journal 52 7 1105 1118 doi 10 1002 j 1538 7305 1973 tb02007 x Cummiskey P Jayant Nikil S Flanagan J L 1973 Adaptive quantization in differential PCM coding of speech The Bell System Technical Journal 52 7 1105 1118 doi 10 1002 j 1538 7305 1973 tb02007 x ISSN 0005 8580 a b c Schroeder Manfred R 2014 Bell Laboratories Acoustics Information and Communication Memorial Volume in Honor of Manfred R Schroeder Springer p 388 ISBN 9783319056609 Gray Robert M 2010 A History of Realtime Digital Speech on Packet Networks Part II of Linear Predictive Coding and the Internet Protocol PDF Found Trends Signal Process 3 4 203 303 doi 10 1561 2000000036 ISSN 1932 8346 Nasir Ahmed T Natarajan Kamisetty Ramamohan Rao January 1974 Discrete Cosine Transform PDF IEEE Transactions on Computers C 23 1 90 93 doi 10 1109 T C 1974 223784 S2CID 149806273 a b c Guckert John Spring 2012 The Use of FFT and MDCT in MP3 Audio Compression PDF University of Utah Retrieved 14 July 2019 Princen J Johnson A Bradley A 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 Vol 12 pp 2161 2164 doi 10 1109 ICASSP 1987 1169405 S2CID 58446992 Princen J Bradley A 1986 Analysis Synthesis filter bank design based on time domain aliasing cancellation IEEE Transactions on Acoustics Speech and Signal Processing 34 5 1153 1161 doi 10 1109 TASSP 1986 1164954 a b c d e f Luo Fa Long 2008 Mobile Multimedia Broadcasting Standards Technology and Practice Springer Science amp Business Media p 590 ISBN 9780387782638 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 S2CID 897622 a b Brandenburg Karlheinz 1999 MP3 and AAC Explained PDF Archived PDF from the original on 2017 02 13 Video Developer Report 2019 PDF Bitmovin 2019 Retrieved 5 November 2019 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 S2CID 897622 Stankovic Radomir S Astola Jaakko T 2012 Reminiscences of the Early Work in DCT Interview with K R Rao PDF Reprints from the Early Days of Information Sciences 60 Retrieved 13 October 2019 Xiph Org Foundation 2009 06 02 Vorbis I specification 1 1 2 Classification Xiph Org Foundation Retrieved 2009 09 22 Terriberry Timothy B Presentation of the CELT codec Presentation PDF Valin Jean Marc Maxwell Gregory Terriberry Timothy B Vos Koen October 2013 High Quality Low Delay Music Coding in the Opus Codec 135th AES Convention Audio Engineering Society arXiv 1602 04845 Darko John H 2017 03 29 The inconvenient truth about Bluetooth audio DAR KO Archived from the original on 2018 01 14 Retrieved 2018 01 13 Ford Jez 2015 08 24 What is Sony LDAC and how does it do it AVHub Retrieved 2018 01 13 Ford Jez 2016 11 22 aptX HD lossless or lossy AVHub Retrieved 2018 01 13 Digital Theater Systems Audio Formats Library of Congress 27 December 2011 Retrieved 10 November 2019 Spanias Andreas Painter Ted Atti Venkatraman 2006 Audio Signal Processing and Coding John Wiley amp Sons p 338 ISBN 9780470041963 Retrieved from https en wikipedia org w index php title Audio coding format amp oldid 1151442824, wikipedia, wiki, book, books, library,

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