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History
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 = German Aerospace Agency) 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.
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 computational
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 responsibilities of L.
van de Kerkhof (Layer I) and G. Stoll (Layer II).
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.
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.
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 that 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 with this reference are higher, which demonstrates
the problem of the term compression ratio for lossy encoders.
Karlheinz Brandenburg used a CD recording of Suzanne Vega's song Tom's Diner to
assess 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 professional sound engineers to
assess the subjective quality of the MPEG Audio formats.
MP3 goes public
A reference simulation software written in C language known as ISO 11172-5 was
developed 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.
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 real-time 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.
MP2, 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 Microsoft Windows).
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.
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 was 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.
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.
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).
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. The use of
formats that supports DRM is in an attempt to prevent piracy of copyright
protected materials, but any computer savvy person can easily rip the DRM from a
song file turning it into a file that is not locked to any computer.
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