Editing MPEG-1 Audio Layer II (section)

==History of development==
{{See also|MP3#History|MPEG-1#Layer II}}

=== MUSICAM ===
MPEG-1 Audio Layer 2 encoding was derived from the MUSICAM (''Masking pattern adapted Universal Subband Integrated Coding And Multiplexing'') audio codec, developed by [[Centre commun d'études de télévision et télécommunications]] (CCETT), [[Philips]], and the [[Institut für Rundfunktechnik]] (IRT) in 1989 as part of the [[EUREKA 147]] pan-European inter-governmental research and development initiative for the development of a system for the broadcasting of audio and data to fixed, portable or mobile receivers (established in 1987).

It began as the [[Digital Audio Broadcast]] (DAB) project managed by Egon Meier-Engelen of the Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt (later on called Deutsches Zentrum für Luft- und Raumfahrt, German Aerospace Center) in Germany. The European Community financed this project, commonly known as EU-147, from 1987 to 1994 as a part of the [[EUREKA]] research program.

The Eureka 147 System comprised three main elements: MUSICAM Audio Coding (''Masking pattern Universal Sub-band Integrated Coding And Multiplexing''), Transmission Coding & Multiplexing and COFDM Modulation.<ref>{{cite web |author=A J Bower |year=1998 |title=Digital Radio — The Eureka 147 DAB System |url=http://www.bbc.co.uk/rd/pubs/papers/paper_21/paper_21.shtml |access-date=2010-08-22 |publisher=BBC |location=UK}}</ref>

MUSICAM was one of the few codecs able to achieve high audio quality at bit rates in the range of 64 to 192&nbsp;kbit/s per monophonic channel. It has been designed to meet the technical requirements of most applications (in the field of broadcasting, telecommunication and recording on digital storage media) — low delay, low complexity, error robustness, short access units, etc.<ref>{{cite book |last1=Dehery |first1=Y.F. |title=&#91;Proceedings&#93; ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing |last2=Lever |first2=M. |last3=Urcun |first3=P. |year=1991 |isbn=0-7803-0003-3 |pages=3605–3608 vol.5 |chapter=A MUSICAM source codec for digital audio broadcasting and storage |doi=10.1109/ICASSP.1991.151054 |s2cid=62615197}}</ref><ref name="aes-musicam">{{cite web |year=1991 |title=AES E-Library – Musicam Source Coding |url=http://www.aes.org/e-lib/browse.cfm?elib=5398 |access-date=2010-08-22}}</ref>

As a predecessor of the MP3 format and technology, the perceptual codec MUSICAM is based on integer arithmetics 32 subbands transform, driven by a psychoacoustic model. It was primarily designed for Digital Audio Broadcasting and digital TV, and disclosed by CCETT(France) and IRT (Germany) in Atlanta during an IEEE-ICASSP conference.<ref>{{cite conference |last1=Dehery |first1=Y.F. |last2=Lever |first2=M. |last3=Urcun |first3=P. |date=May 1991 |title=A MUSICAM source codec for Digital Audio Broadcasting and storage |pages=3605–3608 |doi=10.1109/ICASSP.1991.151054 |isbn=0-7803-0003-3 |work=[Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing}}</ref> This codec incorporated into a broadcasting system using COFDM modulation was demonstrated on air and on the field <ref>{{cite magazine |last=Box |first=Alan |date=1991-04-15 |title=A DAB commentary from Alan Box, EZ communication and chairman NAB DAB task force |url=http://www.americanradiohistory.com/Archive-BC/BC-1991/BC-1991-04-15.pdf |magazine=[[Broadcasting & Cable|Broadcasting]] |pages=26 |volume=150 |number=15}}</ref> together with [[Ici Radio-Canada Télé|Radio Canada]] and [[Communications Research Centre Canada|CRC Canada]] during the NAB show (Las Vegas) in 1991. The implementation of the audio part of this broadcasting system was based on a two chips encoder (one for the subband transform, one for the psychoacoustic model designed by the team of [[G. Stoll]] (IRT Germany), later known as Psychoacoustic model I in the ISO MPEG audio standard) and a real time decoder using one [[Motorola 56001]] [[Digital Signal Processor|DSP]] chip running an integer arithmetics software designed by [[Y.F. Dehery]]'s team ([[Centre commun d'études de télévision et télécommunications|CCETT]], France). The simplicity of the corresponding decoder together with the high audio quality of this codec using for the first time a 48&nbsp;kHz sampling frequency, a 20 bits/sample input format (the highest available sampling standard in 1991, compatible with the AES/EBU professional digital input studio standard) were the main reasons to later adopt the characteristics of MUSICAM as the basic features for an advanced digital music compression codec such as MP3.

The audio coding algorithm used by the Eureka 147 Digital Audio Broadcasting (DAB) system has been subject to the standardization process within the ISO/Moving Pictures Expert Group (MPEG) in 1989–94.<ref name="etsi">{{citation |title=Digital Audio Broadcasting (DAB); DAB to mobile, portable and fixed receivers – Details of 'DE/JTC-DAB' Work Item – ETS 300 401 |date=1995-02-15 |url=http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=976 |access-date=2010-08-23}}</ref><ref>{{citation |title=DAB – Service planning for terrestrial Digital Audio Broadcasting |year=1992 |url=http://www.ebu.ch/trev_252-lau.pdf |access-date=2010-08-22 |archive-url=https://web.archive.org/web/20050504183626/http://www.ebu.ch/trev_252-lau.pdf |archive-date=2005-05-04 |url-status=dead}}</ref> MUSICAM audio coding was used as a basis for some coding schemes of MPEG-1 and MPEG-2 Audio.<ref name="santaclara">{{cite web |year=1990 |title=Status report of ISO MPEG – September 1990 |url=http://mpeg.chiariglione.org/meetings/santa_clara90/santa_clara_press.htm |url-status=dead |archive-url=https://web.archive.org/web/20100214044029/http://mpeg.chiariglione.org/meetings/santa_clara90/santa_clara_press.htm |archive-date=2010-02-14 |access-date=2010-08-22}}</ref> Most key features of MPEG-1 Audio were directly inherited from MUSICAM, including the filter bank, time-domain processing, audio frame sizes, etc. However, improvements were made, and the actual MUSICAM algorithm was not used in the final MPEG-1 Audio Layer II standard.

Since the finalisation of MPEG-1 Audio and MPEG-2 Audio (in 1992 and 1994), the original MUSICAM algorithm is not used anymore.<ref name="mpegfaq" /><ref name="telos">{{cite web |author=Telos Systems |title=Facts about MPEG compression |url=http://www.telos-systems.com/techtalk/mpeg/default.htm |url-status=dead |archive-url=https://web.archive.org/web/20010508092243/http://www.telos-systems.com/techtalk/mpeg/default.htm |archive-date=2001-05-08 |access-date=2010-08-22}}</ref> The name MUSICAM is often mistakenly used when MPEG-1 Audio Layer II is meant. This can lead to some confusion, because the name MUSICAM is trademarked by different companies in different regions of the world.<ref name="mpegfaq" /><ref name="telos" /><ref>{{cite web |author=MUSICAM USA |title=MUSICAM USA Frequently Asked Questions – Isn't MUSICAM simply your implementation of ISO/MPEG Layer 2? |url=http://www.musicamusa.com/faq2.htm |access-date=2010-08-23}}</ref> (Musicam is the name used for MP2 in some specifications for Astra Digital Radio as well as in the BBC's DAB documents.)

The Eureka Project 147 resulted in the publication of European Standard, ETS 300 401 in 1995, for DAB which now has worldwide acceptance. The DAB standard uses the MPEG-1 Audio Layer II (ISO/IEC 11172-3) for 48&nbsp;kHz sampling frequency and the MPEG-2 Audio Layer II (ISO/IEC 13818-3) for 24&nbsp;kHz sampling frequency.<ref>{{citation |title=Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers – Details of 'REN/JTC-DAB-36' Work Item – EN 300 401 |date=2006-06-15 |url=http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=21095 |access-date=2010-08-23}}</ref>

=== MPEG Audio ===
In the late 1980s, [[International Organization for Standardization|ISO]]'s [[Moving Picture Experts Group]] (MPEG) started an effort to standardize digital audio and video encoding, expected to have a wide range of applications in digital radio and TV broadcasting (later [[Digital audio broadcasting|DAB]], [[Digital Multimedia Broadcasting|DMB]], [[Digital video broadcasting|DVB]]), and use on CD-ROM (later [[Video CD]]).<ref>{{cite web |last=Chiariglione |first=Leonardo |date=October 1989 |title=MPEG Press Release |url=http://mpeg.chiariglione.org/meetings/kurihama89/kurihama_press.htm |archive-url=https://web.archive.org/web/20100805102339/http://mpeg.chiariglione.org/meetings/kurihama89/kurihama_press.htm |archive-date=2010-08-05 |publisher=[[Moving Picture Experts Group]] |location=Kurihama}}.</ref> The MUSICAM audio coding was one of 14 proposals for MPEG-1 Audio standard that were submitted to ISO in 1989.<ref name="aes-musicam" /><ref name="santaclara" />

The MPEG-1 Audio standard was based on the existing MUSICAM and ASPEC audio formats.<ref>Digital Video and Audio Broadcasting Technology: A Practical Engineering Guide (Signals and Communication Technology) {{ISBN|3-540-76357-0}} p. 144: "In the year 1988, the MASCAM method was developed at the Institut für Rundfunktechnik (IRT) in Munich in preparation for the digital audio broadcasting (DAB) system. From MASCAM, the MUSICAM (masking pattern universal subband integrated coding and multiplexing) method was developed in 1989 in cooperation with CCETT, Philips and Matsushita."</ref>
The [[MPEG-1]] Audio standard included the three audio "layers" (encoding techniques) now known as Layer I (MP1), Layer II (MP2) and Layer III (MP3).
All algorithms for MPEG-1 Audio Layer I, II and III were approved in 1991 as the committee draft of ISO-11172<ref name="cd-1991">{{cite web |last=Chiariglione |first=Leonardo |date=November 1991 |title=MPEG Press Release |url=http://mpeg.chiariglione.org/meetings/kurihama91/kurihama_press.htm |url-status=dead |archive-url=https://web.archive.org/web/20110503174827/http://mpeg.chiariglione.org/meetings/kurihama91/kurihama_press.htm |archive-date=2011-05-03 |access-date=2010-07-17 |publisher=[[Moving Picture Experts Group]] |location=Kurihama}}</ref><ref name="neuron2-cd-1991">{{cite web |author=ISO |date=November 1991 |title=CD 11172-3 - Coding of Moving Pictures and Associated Audio for Digital Storage Media at up to About 1.5 MBit/s Part 3 Audio |url=http://neuron2.net/library/mpeg1/MPGAUDIO.DOC |archive-url=https://web.archive.org/web/20100611215029/http://neuron2.net/library/mpeg1/MPGAUDIO.DOC |archive-date=June 11, 2010 |access-date=2010-07-17 |publisher=neuron2.net |format=DOC}}</ref><ref>{{cite conference |last1=Patel |first1=Ketan |last2=Smith |first2=Brian C. |last3=Rowe |first3=Lawrence A. |title=Performance of a Software MPEG Video Decoder |url=http://www.cs.unc.edu/~kmp/publications/mm93/MM93-paper.pdf |conference=ACM Multimedia 1993 Conference}} Article's reference 3 is: 'ISO/IEC JTC/SC29, "Coded Representation of Picture, Audio and Multimedia/Hypermedia Information", ''Committee Draft of Standard ISO/IEC 11172'', December 6, 1991'.</ref> and finalized in 1992<ref name="dis-1992">{{cite web |author=ISO |date=1992-11-06 |title=MPEG Press Release, London, 6 November 1992 |url=http://mpeg.chiariglione.org/meetings/london/london_press.htm |url-status=dead |archive-url=https://web.archive.org/web/20100812034709/http://mpeg.chiariglione.org/meetings/london/london_press.htm |archive-date=12 August 2010 |access-date=2010-07-17 |website=Chiariglione.org}}</ref> as part of [[MPEG-1]], the first standard suite by [[MPEG]], which resulted in the international standard '''[[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 11172-3''' (a.k.a. ''MPEG-1 Audio'' or ''MPEG-1 Part 3''), published in 1993.<ref name="11172-3" /> Further work on MPEG audio<ref name="sydney1993">{{cite press release |title=Press Release - Adopted at 22nd WG11 meeting |date=1993-04-02 |publisher=[[International Organization for Standardization]] |url=http://mpeg.chiariglione.org/meetings/sydney93/sydney_press.htm |access-date=2010-07-18 |url-status=dead |archive-url=https://web.archive.org/web/20100806161942/http://mpeg.chiariglione.org/meetings/sydney93/sydney_press.htm |archive-date=2010-08-06}}</ref> was finalized in 1994 as part of the second suite of MPEG standards, [[MPEG-2]], more formally known as international standard '''ISO/IEC 13818-3''' (a.k.a. ''MPEG-2 Part 3'' or [[backward compatible]] ''MPEG-2 Audio'' or ''MPEG-2 Audio BC''<ref name="mpeg-audio-faq-bc">{{cite web |author=ISO |date=October 1998 |title=MPEG Audio FAQ Version 9 - MPEG-1 and MPEG-2 BC |url=http://mpeg.chiariglione.org/faq/mp1-aud/mp1-aud.htm |access-date=2009-10-28 |publisher=ISO}}</ref>), originally published in 1995.<ref name="13818-3" /><ref name="Brandenburg1997">{{cite journal |last1=Brandenburg |first1=Karlheinz |last2=Bosi |first2=Marina |date=February 1997 |title=Overview of MPEG Audio: Current and Future Standards for Low-Bit-Rate Audio Coding |url=http://www.aes.org/e-lib/browse.cfm?elib=7871 |journal=Journal of the Audio Engineering Society |volume=45 |issue=1/2 |pages=4–21 |access-date=30 June 2008}}</ref> MPEG-2 Part 3 (ISO/IEC 13818-3) defined additional bit rates and sample rates for MPEG-1 Audio Layer I, II and III. The new sampling rates are exactly half that of those originally defined for MPEG-1 Audio. MPEG-2 Part 3 also enhanced MPEG-1's audio by allowing the coding of audio programs with more than two channels, up to 5.1 multichannel.<ref name="sydney1993" />

The Layer III ([[MP3]]) component uses a [[lossy compression]] algorithm that was designed to greatly reduce the amount of data required to represent an audio recording and sound like a decent reproduction of the original uncompressed audio for most listeners.

===Emmy Award in Engineering===
[[Centre commun d'études de télévision et télécommunications|CCETT]] (France), [[Institut für Rundfunktechnik|IRT]] (Germany) and [[Philips]] (The Netherlands) won an [[Emmy Award]] in Engineering 2000 for development of a digital audio two-channel compression system known as Musicam or MPEG Audio Layer II.<ref>{{citation |title=National Academey of Television Arts and Sciences, Outstanding Achievement in Technical/Engineering Development Awards |url=http://www.emmyonline.tv/tech/applications/engineering_award_winners_rev3.pdf |access-date=2010-08-01 |archive-url=https://web.archive.org/web/20100414233617/http://www.emmyonline.tv/tech/applications/engineering_award_winners_rev3.pdf |archive-date=2010-04-14 |url-status=dead}}</ref><ref>{{cite web |date=2001-02-11 |title=CCETT - DAB : Digital Audio Broadcasting (archived website) |url=http://www.ccett.fr/eng/03b2.htm |archive-url=https://web.archive.org/web/20010211120613/http://www.ccett.fr/eng/03b2.htm |archive-date=2001-02-11 |access-date=2010-08-01}}</ref>