MP3

MP3 is a popular digital audio encoding and lossy compression format invented and standardised in 1991 by a team of engineers working in the framework of the ISO/IEC MPEG audio committee under the chairmanship of Professor Hans Musmann (University of Hannover - Germany). It was designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. In popular usage, MP3 also refers to files of sound or music recordings stored in the MP3 format on computers.

History

Development

MPEG-1 Audio Layer 2 encoding began as the Digital Audio Broadcast (DAB) project managed by Egon Meier-Engelen of the DFVLR (later on called DLR = Deutsche Luft und Raumfahrt) in Germany. This project was financed by the European Union as a part of the EUREKA research program where it was commonly known as EU-147. EU-147 ran from 1987 to 1994.

Related Topics:
Digital Audio Broadcast - Germany - European Union - EUREKA - 1987 - 1994

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In 1991, there were two proposals available: Musicam (known as Layer 2), and ASPEC (Adaptive Spectral Perceptual Entropy Coding). The Musicam technique, as proposed by Philips (The Netherlands), CCETT (France), IRT (Germany) was chosen due to its simplicity and error robustness, as well as its low computationnal power associated to the encoding of high quality compressed audio. The Musicam format based on subband coding was key to settle the basis of the MPEG Audio compression format (sampling rates, structure of frames, headers, number of samples per frame,). Its technologies and ideas were fully incorporated into the definition of ISO MPEG Audio Layer I and Layer II and further on of the Layer III (MP3) format. Under the chairmanship of Professor Mussmann (University of Hannover) the editing of the standard was made under the responsabilities of L. van de Kerkhof (Layer I) and G. Stoll (Layer II).

Related Topics:
1991 - Musicam - ASPEC

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Further on a working group consisting of J. D. Johnston (US), Gerhard Stoll (Germany), Yves-François Dehery (France), Karlheinz Brandenburg (Germany) took ideas from Musicam and ASPEC, added some of their own ideas and created MP3, which was designed to achieve the same quality at 128 kbit/s as MP2 at 192 kbit/s.

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All algorithms were finalized in 1992 as part of MPEG-1, the first standard suite by MPEG, which resulted in the international standard ISO/IEC 11172-3, published in 1993. Further work on MPEG audio 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, originally published in 1995.

Related Topics:
1992 - MPEG-1 - MPEG - ISO - IEC - 1993 - 1994 - MPEG-2 - 1995

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Compression efficiency of encoders is typically defined by the bit rate because compression rate depends on the bit depth and sampling rate of the input signal. Nevertheless, there are often published compression rates which use the CD parameters as references (44.1 kHz, 2 channels at 16 bits per channel or 2x16 bit). Sometimes the Digital Audio Tape (DAT) SP parameters are used (48 kHz, 2x16 bit). Compression ratios for this reference is higher, which demonstrates the problem of the term compression ratio for lossy encoders.

Related Topics:
Sampling rate - CD - KHz - Digital Audio Tape

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Karlheinz Brandenburg used a CD recording of Suzanne Vega's song Tom's Diner to asses the MP3 compression algorithm. This song was chosen because of its softness and simplicity, making it easier to hear imperfections in the compression format during playbacks. Some more serious and critical audio excerpts (glockenspiel, triangle, accordion, ...) were taken from the EBU V3/SQAM reference compact disc and have been used by professionnal sound engineers to assess the subjective quality of the MPEG Audio formats.

Related Topics:
Suzanne Vega - Tom's Diner - Compression algorithm

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MP3 goes public

A reference simulation software written in C language known as ISO 11172-5 was developped by the members of the ISO MPEG Audio committee in order to produce bit compliant MPEG Audio files (Layer 1, Layer 2, Layer 3). Working in non real time on a number of operating systems it was able to demonstrate the first real time hardware decoding (DSP based) of compressed audio. Some other real time implementation of MPEG Audio encoders were available for the purpose of digital broadcasting (radio DAB, television DVB) towards consumer receivers and set top boxes.

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Later on, on July 7 1994 the Fraunhofer Society released the first software MP3 encoder called l3enc. The filename extension .mp3 was chosen by the Fraunhofer team on July 14, 1995 (previously, the files had been named .bit). With the first realtime software MP3 player Winplay3 (released September 9th, 1995) many people were able to encode and playback MP3 files on their PCs. Because of the relatively small hard drives back in that time (~500 MB) the technology was essential to store music for listening pleasure on a computer.

Related Topics:
July 7 - 1994 - L3enc - Filename extension - July 14 - 1995 - Winplay3 - Hard drive - MB

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MP2 and MP3 and the Internet

In October 1993, MP2 (MPEG-1 Audio Layer 2) files appeared on the Internet and were often played back using the Xing MPEG Audio Player, and later in a program for Unix by Tobias Bading called MAPlay which was initially released on February 22nd, 1994 (MAPlay was also ported to the Microsoft Windows OS).

Related Topics:
October - 1993 - MP2 - Internet - Xing - Unix - Tobias Bading - MAPlay - Microsoft Windows - OS

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Initially the only encoder available for MP2 production was the Xing Encoder, accompanied by the program CDDA2WAV, a CD ripper that transformed CD audio tracks to computer data files.

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The Internet Underground Music Archive (IUMA) is generally recognized as the start of the on-line music revolution. IUMA was the Internet's first high-fidelity music web site, hosting thousands of authorized MP2 recordings before MP3 or the web were popularized. IUMA was started by Rob Lord (who later headed pioneering Nullsoft) and Jeff Patterson, both from the University of California, Santa Cruz, in 1993. Other founding members include Jon Luini, Brandee Selck, and Ahin Savara.

Related Topics:
Rob Lord - Nullsoft - Jeff Patterson

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In the first half of 1995 through the late 1990s, MP3 files began flourishing on the Internet. MP3 popularity was mostly due to, and interchangeable with, the successes of companies and software packages like Nullsoft's Winamp(released in 1997), mpg123, and Napster (released in 1999). Those programs made it very easy for the average user to playback, create, share, and collect MP3s.

Related Topics:
1995 - 1990s - Internet - Winamp - 1997 - Mpg123 - Napster - 1999

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Controversies regarding peer-to-peer file sharing of MP3 files have flourished in recent years — largely because high compression enables sharing of files that would otherwise be too large and cumbersome to share. Due to the vastly increased spread of MP3s through the internet some major record labels reacted by filing a lawsuit against Napster to protect their Copyrights (see also intellectual property).

Related Topics:
Peer-to-peer - File sharing - Lawsuit against Napster - Copyright - Intellectual property

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Commercial online music distribution services (like the iTunes Music Store) usually prefer other/proprietary music file formats that support Digital Rights Management (DRM) to control and restrict the use of digital music. This preference is most likely chosen in an attempt to prevent piracy of copyrighted materials, but most users with at least an intermediate understanding of computers will know that it's just a matter of time before someone else makes it easy to convert such proprietary file formats.

Related Topics:
ITunes Music Store - Digital Rights Management

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