MP3: Difference between revisions

'''MP3''' (formally '''MPEG-1 Audio Layer III''' or '''MPEG-2 Audio Layer III''')<ref name="rfc5219" /> is a [[audio coding format|coding format]] for [[digital audio]] developed largely by the [[Fraunhofer Society]] in Germany under the lead of [[Karlheinz Brandenburg]],<ref>{{Cite web|url=https://www.youtube.com/watch?v=cuU16whZ-Fs|title=73. "Father" of the MP3, Karlheinz Brandenburg|via=www.youtube.com}}</ref><ref>{{Cite web|url=https://www.internethistorypodcast.com/2015/07/on-the-20th-birthday-of-the-mp3-an-interview-with-the-father-of-the-mp3-karlheinz-brandenburg/|title=On the 20th Birthday of the MP3, An Interview With The "Father" of the MP3, Karlheinz Brandenburg}}</ref> with support from other digital scientists in other countries. Originally defined as the third audio format of the [[MPEG-1]] standard, it was retained and further extended — definingextended—defining additional bit- rates and support for more [[surround channels|audio channels]] — as—as the third audio format of the subsequent [[MPEG-2]] standard. A third version, known as MPEG-2.5 — extended5—extended to better support lower [[bit rate]]s — iss—is commonly implemented, but is not a recognized standard.

Concerning [[audio compression (data)|audio compression]] (the aspect of the standard most apparent to end-users, and for which it is best known), MP3 uses [[lossy compression|lossy data- compression]] to encode data using inexact approximations and the partial discarding of data. This allows a large reduction in file sizes when compared to uncompressed audio. The combination of small size and acceptable fidelity led to a boom in the distribution of music over the Internet in the mid-to-late 1990s, with MP3 serving as an enabling technology at a time when bandwidth and storage were still at a premium. The MP3 format soon became associated with controversies surrounding [[copyright infringement]], [[music piracy]], and the file -[[ripping]]/ and [[file sharing|sharing]] services [[MP3.com#Original_version|MP3.com]] and [[Napster]], among others. With the advent of [[portable media player]]s, a product category also including [[smartphones]], MP3 support remains near-universal.

MP3 compression works by reducing (or approximating) the accuracy of certain components of sound that are considered (by psychoacoustic analysis) to be beyond the [[Hearing range#Humans|hearing capabilities]] of most humans. This method is commonly referred to as perceptual coding or as [[psychoacoustics|psychoacoustic]] modeling.<ref name="Jayant1993" /> The remaining audio information is then recorded in a space-efficient manner, using [[Modified discrete cosine transform|MDCT]] and [[Fast Fourier transform|FFT]] algorithms. Compared to [[Compact Disc Digital Audio|CD-quality digital audio]], MP3 compression can commonly achieve a 75 to 9575–95% reduction in size. For example, an MP3 encoded at a constant bit rate of 128&nbsp;kbit/s would result in a file approximately 9% of the size of the original CD audio.<ref>{{cite web |url= https://www.loc.gov/preservation/digital/formats/fdd/fdd000012.shtml |title= MP3 (MPEG Layer III Audio Encoding) |date= 27 July 2017 |publisher= The Library of Congress |access-date= 9 November 2017}}</ref> In the early 2000s, compact disc players increasingly adopted support for playback of MP3 files on data CDs.

The [[Moving Picture Experts Group]] (MPEG) designed MP3 as part of its [[MPEG-1]], and later [[MPEG-2]], standards. MPEG-1 Audio (MPEG-1 Part 3), which included MPEG-1 Audio Layer I, II, and III, was approved as a committee draft for an [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] standard in 1991,<ref name="cd-1991" /><ref name="neuron2-cd-1991" /> finalized in 1992,<ref name="dis-1992" /> and published in 1993 as ISO/IEC 11172-3:1993.<ref name="11172-3" /> An MPEG-2 Audio (MPEG-2 Part 3) extension with lower sample- and bit- rates was published in 1995 as ISO/IEC 13818-3:1995.<ref name="13818-3" /><ref name="mpeg-audio-faq-bc" /> It requires only minimal modifications to existing MPEG-1 decoders (recognition of the MPEG-2 bit in the header and addition of the new lower sample and bit rates).