MP3

MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a digital audio encoding format using a form of lossy data compression.
It is a common audio format for consumer audio storage, as well as a de facto standard encoding for the transfer and playback of music on digital audio players.
MP3's use of a lossy compression algorithm is designed to greatly reduce the amount of data required to represent the audio recording and still sound like a faithful reproduction of the original uncompressed audio for most listeners, but is not considered High Fidelity audio by the elite connoisseur. An MP3 file that is created using the mid-range bitrate setting of 128 kbit/s will result in a file that is typically about 1/10th the size of the CD file created from the original audio source. An MP3 file can also be constructed at higher or lower bitrates, with higher or lower resulting quality.Reference : http://en.wikipedia.org/wiki/Mp3

MP4 versus

The existence of two different file extensions for naming audio-only MP4 files has been a source of confusion among users and multimedia playback software. Since MPEG-4 Part 14 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, making it impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone. In response, Apple Inc. started using and popularizing the .m4a file extension. Software capable of audio/video playback should recognize files with either .m4a or .mp4 file extensions, as would be expected, as there are no file format differences between the two. Most software capable of creating MPEG-4 audio will allow the user to choose the filename extension of the created MPEG-4 files.
Reference : http://en.wikipedia.org/wiki/Mp4

History of MP4

MPEG-4 Part 14 was based on Apple’s QuickTime container format. MPEG-4 Part 14 is essentially identical to the QuickTime MOV format, but formally specifies support for Initial Object Descriptors (IOD) and other MPEG features.
Reference : http://en.wikipedia.org/wiki/Mp4

Aggregators

Aggregators such as The Hype Machine and Elbo.ws track MP3 blog posts and display the most recently updated posts on its front page. The services are meant to provide a snapshot of what's going on in music blogging and make it easier to search through recently posted MP3s. The Hype Machine features a list of the most popular tracks of the last 3 days as well as the most blogged bands and most popular searches. Elbo.ws has a similar feature listing which Bands, Tracks, and Videos are currently "hot." Music Blog Aggregators have caused a boom in MP3 blog readership and accessibility. Aggregators use RSS technology to collect data from MP3 blogs and link to the individual blog posts instead of directly to the MP3s.
Reference : http://en.wikipedia.org/wiki/MP3_blog

MP3 blog History 2

In 2006, Rolling Stone did an article tracking "blog buzz" called First Hype, Then Kill with the subtitle "How the geeks who control the music blogosphere destroy the bands they love." [2] It followed the hype of bands like Tapes N' Tapes, Clap Your Hands Say Yeah, Arctic Monkeys and Cold War Kids. While the article brought exposure to mp3 blogs, it was blasted on blogs for misrepresenting what impact they have on a band's career. According to the chart, Gorilla vs Bear giving a good review of Cold War Kids was the highpoint of the band's career, and signing a record deal marked the beginning of their decline. It also assumed that music blogs have collective opinions instead of an array of many different musical leanings.[citation needed]
In 2006, Sirius Satellite Radio began broadcasting "blog radio", a show on the College/Indie Rock channel Left of Center. The show lets music bloggers talk about the latest in the indie-rock scene.
Reference : http://en.wikipedia.org/wiki/MP3_blog

MP3 blog History

Among the very first MP3 blogs were Fluxblog and Stereogum. The latter began as a music-related LiveJournal in 2002, though its format was focused on indie/pop gossip rather than MP3s. Fluxblog's trumpeting of LCD Soundsystem's "Yeah (Stupid Version)" in early 2004 brought increased attention to MP3 blogs. A May 2004 story on National Public Radio[1] further galvanized the trend, and today there are thousands of MP3 blogs covering a cornucopia of musical styles.
A significant number of indie music labels, promotional agencies and hundreds of artists regularly send promo CDs to MP3 blogs in the hopes of gaining free publicity. Major labels with small acts to promote have also attempted to use MP3 blogs. In 2004, Warner Bros. gave permission for a song by their act The Secret Machines to be posted by the MP3 blog Music (For Robots). This drew attention not only for the song and the label granting permissions, but also due to the fact that several comments praising the track came from IP addresses within the Warner Bros. network. The publicity generated by MP3 blogs crossed the line from the internet to TV in early 2005, when Music (For Robots) was featured during MTV's Total Request Live program for bringing the Hysterics, a Brooklyn rock band composed of four 14 and 15 year-old high school students, to the network's attention.
Reference : http://en.wikipedia.org/wiki/MP3_blog

MP3 blog

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An MP3 blog is a type of blog in which the creator makes music files, normally in the MP3 format, available for download. They are also known as "musicblogs" or "audioblogs". MP3 blogs have become increasingly popular since 2003. The music posted ranges from hard-to-find rarities that have not been issued in many years to more contemporary offerings, and selections are often restricted to a particular musical genre or theme. Some MP3 blogs offer music in Advanced Audio Coding (AAC) or Ogg formats.
Reference : http://en.wikipedia.org/wiki/MP3_blog

audio player Controversy

Although these issues aren't usually controversial within digital audio players, they are matters of continuing controversy and litigation, including but not limited to content distribution and protection, and digital rights management (DRM).
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

Ancillery data benefits

While MP3 players and iPods are primarily tailored for music (and some for video as well), they can also serve as backup media and can be an alternative to buying stand-alone flash drives with them. However some models don't use file systems, and notable examples of them would be iPod Touch although other iPods have hidden song data on their file systems, and others use the Media Transfer Protocol which doesn't allow direct copy of ancillery data, however than can be circumvented by renaming files of other extentions (such as *.zip) to *.MP3 to allow ancillery data to be copied on them.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

Common formats supported

MP3 is the dominant format, and is nearly universally supported.[12] The main alternative formats are AAC, supported on players from Apple, ATRAC, on players from Sony, and WMA, on players from Microsoft and partners. Unlike MP3, these formats support DRM restrictions, which are often added to files from paid download services. Open source formats which are completely patent-free are available but less widely supported – examples include Ogg Vorbis, FLAC, Speex, and Module file formats.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

Audio acquisition

All commercially available digital audio players can play music that has been ripped from Compact Discs via computer. In addition to ripped CD tracks, many digital audio players can accept downloaded music from online music stores. However, such stores often use proprietary formats and DRM, which means that the tracks can only be played on suitably licensed and restricted devices. For example, purchased songs from iTunes might not work on any DAP other than an Apple iPod.
There are also music online communities such as GarageBand.com where music is available at no cost under Creative Commons licenses.
Another way of getting audio files is to rip the songs from radio broadcasts. Many players have the ability to record songs played on the built-in FM tuner. Recently, a Swedish company called PopCatcher has developed a technology to save songs from Internet radio and can distinguish between songs, DJ talks, and commercials for convenience.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

audio player History 3

In October 2001, Apple Computer (now known as Apple Inc.) unveiled the first generation iPod, the 5 GB hard drive based DAP with a 1.8" Toshiba drive. Having focused on developing an intuitive user interface, the smaller form factor and industrial design made the player notable within users of the Macintosh community. In July 2002, Apple introduced the second generation update to the iPod. It was compatible with Windows computers through Musicmatch Jukebox (now known as Y!Music Musicmatch Jukebox). The iPod series, which grew to include microdrive and flash-based players, has become the market leader in DAPs.
In 2002, Archos released the first official PMP, the Archos Jukebox Multimedia.[11] Manufacturers have since implemented abilities to view images and play videos into their devices.
Although online music services such as RealNetworks’ Rhapsody offered legal downloads through a subscription plan, the launch of the iTunes Store in 2003 established the model of selling individual songs for purchase.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

audio player History 2

The Rio PMP300 from Diamond Multimedia was introduced in September 1998, a few months after the MPMan. It was a success during the holiday season, with sales exceeding expectations. Interest and investment in digital music were subsequently spurred from itThe Recording Industry Association of America (RIAA) soon filed a lawsuit,[ alleging that the device encouraged copying music illegally, but Diamond won a legal victory on the shoulders of the Sony Corp. v. Universal City Studios case and DAPs were legally ruled as electronic devices.[8] Because of the player's notoriety as the target of a major lawsuit, the Rio is erroneously assumed to be the first DAP.
In 1998, Compaq made the first hard drive based DAP using a 2.5" laptop drive. It was licensed to HanGo Electronics (now known as Remote Solution), which first sold the PJB-100 (Personal Jukebox) in 1999. The player had an initial capacity of 4.8 GB, which was advertised to be able to hold 1200 songs.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

audio player History

The predecessors to digital audio players are portable CD and MiniDisc players, which are commonly known as "Portable Audio Devices". Although the data is digitally stored on discs, neither one is able to support digital file formats.
The first mass-produced DAP was created in 1997 by SaeHan Information Systems, which domestically sold its “MPMan” player in the middle of 1998. The South Korean company then licensed the players to Eiger Labs which distributed them - now branded as Eiger Labs MPMan F10 - to the North American market during the summer of 1998.[4] The flash-based players were available in 32 MB storage capacity.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

Digital audio player

More commonly referred to as an MP3 player, a digital audio player ("DAP") is a portable consumer electronics device that stores, organizes and plays audio files. Some DAPs are also referred as portable media players as they have image-viewing and/or video-playing support. Most DAPs are powered by rechargeable batteries, some of which are not user replaceable. Listening to music stored on DAPs is typically through earphones connected with a 3.5 mm jack.
Reference : http://en.wikipedia.org/wiki/Digital_audio_player

Alternative technologies

Many other lossy and lossless audio codecs exist. Among these, mp3PRO, AAC, and MP2 are all members of the same technological family as MP3 and depend on roughly similar psychoacoustic models. The Fraunhofer Gesellschaft owns many of the basic patents underlying these codecs as well, with others held by Dolby Labs, Sony, Thomson Consumer Electronics, and AT&T.
Reference : http://en.wikipedia.org/wiki/Mp3

Licensing and patent issues 4

On February 16, 2007, Texas MP3 Technologies sued Apple, Samsung Electronics and Sandisk with a patent-infringement lawsuit regarding portable MP3 players. The suit was filed in Marshall, Texas; this is a common location for patent infringement suits due to speedy trials. Texas MP3 Technologies claimed infringement with U.S. patent 7,065,417, awarded in June 2006 to multimedia chip-maker SigmaTel, covering "an MPEG portable sound reproducing system and a method for reproducing sound data compressed using the MPEG method."
Alcatel-Lucent also claims ownership of several patents relating to MP3 encoding and compression, inherited from AT&T-Bell Labs. In November 2006, (prior to the companies' merger) Alcatel filed a lawsuit against Microsoft (see Alcatel-Lucent v. Microsoft), alleging infringement of seven of its patents. On February 23, 2007 a San Diego court upheld the suit, and awarded Alcatel-Lucent a record-breaking US$1.52 billion in damages. Microsoft has said it will appeal the verdict, maintaining that the federal jury's decision is "unsupported by the law or facts", since Microsoft had already paid US$16 million to license the technology from Fraunhofer IIS, which, it claims, is "the industry-recognized rightful licensor". A week later on March 2, U.S. District Judge Rudi Brewster ruled from the bench in a related suit and dismissed all of Alcatel-Lucent's patents claims relating to speech recognition. Alcatel-Lucent plans to appeal the ruling.
In short, with Thomson, Fraunhofer IIS, Sisvel (and its U.S. subsidiary Audio MPEG), Texas MP3 Technologies, and Alcatel-Lucent all claiming legal control of relevant MP3 patents related to decoders, the legal status of MP3 remains unclear in countries where those patents are valid.
Reference : http://en.wikipedia.org/wiki/Mp3

Licensing and patent issues 3

Additionally, patent holders declined to enforce license fees on free and open source decoders, which allows many free MP3 decoders to develop. Furthermore, while attempts have been made to discourage distribution of encoder binaries, Thomson has stated that individuals who use free MP3 encoders are not required to pay fees. Thus, while patent fees have been an issue for companies that attempt to use MP3, they have not meaningfully impacted users, which allows the format to grow in popularity.
Sisvel S.p.A. and its U.S. subsidiary Audio MPEG, Inc. previously sued Thomson for patent infringement on MP3 technology, but those disputes were resolved in November 2005 with Sisvel granting Thomson a license to their patents. Motorola also recently signed with Audio MPEG to license MP3-related patents.
In September 2006 German officials seized MP3 players from SanDisk's booth at the IFA show in Berlin after an Italian patents firm won an injunction on behalf of Sisvel against SanDisk in a dispute over licencing rights. The injunction was later reversed by a Berlin judge; but that reversal was in turn blocked the same day by another judge from the same court, "bringing the Patent Wild West to Germany" in the words of one commentator. Reference : http://en.wikipedia.org/wiki/Mp3

Licensing and patent issues 2

In September 1998, the Fraunhofer Institute sent a letter to several developers of MP3 software stating that a license was required to "distribute and/or sell decoders and/or encoders". The letter claimed that unlicensed products "infringe the patent rights of Fraunhofer and THOMSON. To make, sell and/or distribute products using the [MPEG Layer-3] standard and thus our patents, you need to obtain a license under these patents from us."
These patent issues significantly slowed the development of unlicensed MP3 software[citation needed] and led to increased focus on creating and popularizing alternatives such as Vorbis, AAC, and WMA. Microsoft chose to move away from MP3 to its own proprietary Windows Media format to avoid licensing issues associated with these patents. Until the key patents expires, unlicensed encoders and players could be infringing in countries where the patents are valid.
Reference : http://en.wikipedia.org/wiki/Mp3

Licensing and patent issues

A large number of different organizations have claimed ownership of patents necessary to implement MP3 (decoding and/or encoding). These different claims have led to a number of legal actions, and legal threats, from a variety of sources, resulting in uncertainty about what is necessary to legally create products with MP3 support in countries that permit software patents.
The various patents claimed to cover MP3 by different patent-holders have many different expiration dates, ranging from 2007 to 2017 in the U.S.
Thomson Consumer Electronics claims to control MP3 licensing of the MPEG-1/2 Layer 3 patents in many countries, including the United States, Japan, Canada and EU countries. Thomson has been actively enforcing these patents.
For current information about Fraunhofer IIS and Thomson's patent portfolio and licensing terms and fees see their website mp3licensing.com. MP3 license revenues generated ca. 100 million Euro revenue to the Fraunhofer Society in 2005.
Reference : http://en.wikipedia.org/wiki/Mp3

Volume normalization

different volumes, it may be useful to store volume information about a file in the tag so that at playback time, the volume can be dynamically adjusted.
A few standards for encoding the gain of an MP3 file have been proposed. The idea is to normalize the average volume (not the volume peaks) of audio files, so that the volume does not change between consecutive tracks. This should not be confused with dynamic range compression (DRC), which is a form of normalization used in audio mastering.
Listeners who prefer to experience music as it was intended to be heard on the original compact disc may prefer to not use volume normalization, because the average volume of each track was set intentionally by a professional mastering engineer.
The most popular and widely used solution for storing replay gain is known simply as "Replay Gain". Typically, the average volume and clipping information about the audio track is stored in its metadata tag.
Reference : http://en.wikipedia.org/wiki/Mp3

File structure

An MP3 file is made up of multiple MP3 frames, which consist of the MP3 header and the MP3 data. This sequence of frames is called an Elementary stream. Frames are not independent items ("byte reservoir") and therefore cannot be extracted on arbitrary frame boundaries. The MP3 data is the actual audio payload. The diagram shows that the MP3 header consists of a sync word, which is used to identify the beginning of a valid frame. This is followed by a bit indicating that this is the MPEG standard and two bits that indicate that layer 3 is used; hence MPEG-1 Audio Layer 3 or MP3. After this, the values will differ, depending on the MP3 file. ISO/IEC 11172-3 defines the range of values for each section of the header along with the specification of the header. Most MP3 files today contain ID3 metadata, which precedes or follows the MP3 frames; this is also shown in the diagram.
Reference : http://en.wikipedia.org/wiki/Mp3

Bit rate

Several bit rates are specified in the MPEG-1 Layer 3 standard: 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 192, 224, 256 and 320 kbit/s, and the available sampling frequencies are 32, 44.1 and 48 kHz. A sample rate of 44.1 kHz is almost always used, because this is also used for CD audio, the main source used for creating MP3 files. A greater variety of bit rates are used on the Internet. 128 kbit/s is the most common, beause it typically offers adequate audio quality in a relatively small space. 192 kbit/s is often used by those who notice artifacts at lower bit rates. As the Internet bandwidth availability and hard drive sizes have increased, 128 kbit/s bitrate files are slowly being replaced with higher bitrates like 192 kbit/s, with some being encoded up to MP3's maximum of 320 kbit/s. It is unlikely that higher bit rates will be popular with any lossy audio codec as higher bit rates than 320 kbit/s encroach on the domain of lossless codecs such as FLAC.
By contrast, uncompressed audio as stored on a compact disc has a bit rate of 1,411.2 kbit/s (16 bits/sample × 44100 samples/second × 2 channels / 1000 bits/kilobit).
Some additional bit rates and sample rates were made available in the MPEG-2 and the (unofficial) MPEG-2.5 standards: bit rates of 8, 16, 24, and 144 kbit/s and sample rates of 8, 11.025, 12, 16, 22.05 and 24 kHz.
Non-standard bit rates up to 640 kbit/s can be achieved with the LAME encoder and the freeformat option, although few MP3 players can play those files. According to the ISO standard, decoders are only required to be able to decode streams up to 320 kbit/s.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Audio quality 3

The simplest type of MP3 file uses one bit rate for the entire file — this is known as Constant Bit Rate (CBR) encoding. Using a constant bit rate makes encoding simpler and faster. However, it is also possible to create files where the bit rate changes throughout the file. These are known as Variable Bit Rate (VBR) files. The idea behind this is that, in any piece of audio, some parts will be much easier to compress, such as silence or music containing only a few instruments, while others will be more difficult to compress. So, the overall quality of the file may be increased by using a lower bit rate for the less complex passages and a higher one for the more complex parts. With some encoders, it is possible to specify a given quality, and the encoder will vary the bit rate accordingly. Users who know a particular "quality setting" that is transparent to their ears can use this value when encoding all of their music, and not need to worry about performing personal listening tests on each piece of music to determine the correct settings.
In a listening test, MP3 encoders at low bit rates performed significantly worse than those using more modern compression methods (such as AAC). In a 2004 public listening test at 32 kbit/s, the LAME MP3 encoder scored only 1.79/5 — behind all modern encoders — with Nero Digital HE AAC scoring 3.30/5.
Perceived quality can be influenced by listening environment (ambient noise), listener attention, and listener training and in most cases by listener audio equipment (such as sound cards, speakers and headphones).
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Audio quality 3

Quality is heavily dependent on the choice of encoder and encoding parameters. While quality around 128 kbit/s was somewhere between annoying and acceptable with older encoders, modern MP3 encoders can provide adequate quality at those bit rates (January 2006). However, in 1998, MP3 at 128 kbit/s was only providing quality equivalent to AAC-LC at 96 kbit/s and MP2 at 192 kbit/s.
The transparency threshold of MP3 can be estimated to be at about 128 kbit/s with good encoders on typical music as evidenced by its strong performance in the above test, however some particularly difficult material, or music encoded for the use of people with more sensitive hearing can require 192 kbit/s or higher. As with all lossy formats, some samples cannot be encoded to be transparent for all users.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Audio quality 2

Besides the bit rate of an encoded piece of audio, the quality of MP3 files also depends on the quality of the encoder itself, and the difficulty of the signal being encoded. As the MP3 standard allows quite a bit of freedom with encoding algorithms, different encoders may feature quite different quality, even when targeting similar bit rates. As an example, in a public listening test featuring two different MP3 encoders at about 128 kbit/s, one scored 3.66 on a 1–5 scale, while the other scored only 2.22.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Audio quality

When performing lossy audio encoding, such as creating an MP3 file, there is a trade-off between the amount of space used and the sound quality of the result. Typically, the creator is allowed to set a bit rate, which specifies how many kilobits the file may use per second of audio, for example, when ripping a compact disc to this format. The lower the bit rate used, the lower the audio quality will be, but the smaller the file size. Likewise, the higher the bit rate used, the higher the quality, and therefore, larger the resulting file will be.
Files encoded with a lower bit rate will generally play back at a lower quality. With too low a bit rate, "compression artifacts" (i.e., sounds that were not present in the original recording) may be audible in the reproduction. Some audio is hard to compress because of its randomness and sharp attacks. When this type of audio is compressed, artifacts such as ringing or pre-echo are usually heard. A sample of applause compressed with a relatively low bitrate provides a good example of compression artifacts.
Reference : http://en.wikipedia.org/wiki/Mp3

Decoding audio MP3

Decoding, on the other hand, is carefully defined in the standard. Most decoders are "bitstream compliant", which means that the decompressed output - that they produce from a given MP3 file - will be the same (within a specified degree of rounding tolerance) as the output specified mathematically in the ISO/IEC standard document. The MP3 file has a standard format, which is a frame that consists of 384, 576, or 1152 samples (depends on MPEG version and layer), and all the frames have associated header information (32 bits) and side information (9, 17, or 32 bytes, depending on MPEG version and stereo/mono). The header and side information help the decoder to decode the associated Huffman encoded data correctly.
Therefore, comparison of decoders is usually based on how computationally efficient they are (i.e., how much memory or CPU time they use in the decoding process).
Reference : http://en.wikipedia.org/wiki/Mp3

Encoding audio MP3

The MPEG-1 standard does not include a precise specification for an MP3 encoder. Implementers of the standard were supposed to devise their own algorithms suitable for removing parts of the information in the raw audio (or rather its MDCT representation in the frequency domain). During encoding, 576 time domain samples are taken and are transformed to 576 frequency domain samples. If there is a transient, 192 samples are taken instead of 576. This is done to limit the temporal spread of quantization noise accompanying the transient. (See psychoacoustics.)
As a result, there are many different MP3 encoders available, each producing files of differing quality. Comparisons are widely available, so it is easy for a prospective user of an encoder to research the best choice. It must be kept in mind that an encoder that is proficient at encoding at higher bit rates (such as LAME) is not necessarily as good at lower bit rates.Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Development 5

All algorithms were approved in 1991 and 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 ratio depends on the bit depth and sampling rate of the input signal. Nevertheless, compression ratios are often published. They may use the CD parameters as references (44.1 kHz, 2 channels at 16 bits per channel or 2×16 bit), or sometimes the Digital Audio Tape (DAT) SP parameters (48 kHz, 2×16 bit). Compression ratios with this latter reference are higher, which demonstrates the problem with use 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 nearly monophonic nature and wide spectral content, making it easier to hear imperfections in the compression format during playbacks. Some jokingly refer to Suzanne Vega as "The mother of MP3". Some more critical audio excerpts (glockenspiel, triangle, accordion, etc.) 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. It is important to understand that Suzanne Vega is recorded in an interesting fashion that results in substantial difficulties that arise due to Binaural Masking Level Depression (BMLD).
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Development 4

In 1991, there were two proposals available: Musicam, and ASPEC - (Short excerpt on German Wikipedia) (Adaptive Spectral Perceptual Entropy Coding). The Musicam technique, as proposed by Philips (The Netherlands), CCETT (France) and Institut für Rundfunktechnik (Germany) was chosen due to its simplicity and error robustness, as well as its low computational power associated with the encoding of high quality compressed audio. The Musicam format, based on sub-band coding, was the basis of the MPEG Audio compression format (sampling rates, structure of frames, headers, number of samples per frame). Much of its technology and ideas were 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 Musmann (University of Hannover) the editing of the standard was made under the responsibilities of Leon van de Kerkhof (Layer I) and Gerhard Stoll (Layer II).
A working group consisting of Leon van de Kerkhof (The Netherlands), Gerhard Stoll (Germany), Leonardo Chiariglione (Italy), Yves-François Dehery (France), Karlheinz Brandenburg (Germany) and James D.Johnston (USA) took ideas from ASPEC, integrated the filterbank from Layer 2, 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.Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Development 3

MPEG-1 Audio Layer 2 encoding 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. This project was financed by the European Union as a part of the EUREKA research program where it was commonly known as EU-147, which ran from 1987 to 1994.
As a doctoral student at Germany's University of Erlangen-Nuremberg, Karlheinz Brandenburg began working on digital music compression in the early 1980s, focusing on how people perceive music. He completed his doctoral work in 1989 and became an assistant professor at Erlangen-Nuremberg. While there, he continued to work on music compression with scientists at the Fraunhofer Society (in 1993 he joined the staff of the Fraunhofer Institute). Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Development 2

The immediate predecessors of MP3 were "Optimum Coding in the Frequency Domain" (OCF), and Perceptual Transform Coding (PXFM). These two codecs, along with block-switching contributions from Thomson-Brandt, were merged into a codec called ASPEC, which was submitted to MPEG, and which won the quality competition, but that was mistakenly rejected as too complex to implement. The first practical implementation of an audio perceptual coder (OCF) in hardware (Krasner's hardware was too cumbersome and slow for practical use), was which was an implementation of a psychoacoustic transform coder based on Motorola 56000 DSP chips. MP3 is directly descended from OCF and PXFM. MP3 represents the outcome of the collaboration of Dr. Karlheinz Brandenburg, working as a PostDoc at AT&T-Bell Labs with Mr. James D. Johnston of AT&T-Bell Labs, collaborating with the Fraunhofer Society for Integrated Circuits, Erlangen, with relatively minor contributions from the MP2 branch of psychoacoustic sub-band coders.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 (more)

MP3 is an audio-specific format. It was invented by a team of international engineers at Philips, CCETT (Centre commun d'études de télévision et télécommunications), IRT, AT&T-Bell Labs and Fraunhofer Society, and it became an ISO/IEC standard in 1991. The compression works by reducing accuracy of certain parts of sound that are deemed beyond the auditory resolution ability of most people. This method is commonly referred to as Perceptual Coding.
It provides a representation of sound within a short term time/frequency analysis window, by using psychoacoustic models to discard or reduce precision of components less audible to human hearing, and recording the remaining information in an efficient manner. This is relatively similar to the principles used by JPEG, an image compression format.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 (more)

MP3 is an audio-specific format. It was invented by a team of international engineers at Philips, CCETT (Centre commun d'études de télévision et télécommunications), IRT, AT&T-Bell Labs and Fraunhofer Society, and it became an ISO/IEC standard in 1991. The compression works by reducing accuracy of certain parts of sound that are deemed beyond the auditory resolution ability of most people. This method is commonly referred to as Perceptual Coding.
It provides a representation of sound within a short term time/frequency analysis window, by using psychoacoustic models to discard or reduce precision of components less audible to human hearing, and recording the remaining information in an efficient manner. This is relatively similar to the principles used by JPEG, an image compression format.
Reference : http://en.wikipedia.org/wiki/Mp3

MP3 Development

The psycho-acoustic masking codec was first proposed, apparently independently in 1979, by Manfred Schroeder, et al. from AT&T-Bell Labs in Murray Hill, NJ, and M. A.Krasner both in the United States. Krasner was the first to publish and to produce hardware, but the publication of his results as a relatively obscure Lincoln Laboratory Technical Report did not immediately influence the mainstream of psychoacoustic codec development. Manfred Schroeder was already a well known and revered figure in the world wide community of acoustical and electrical engineers and his paper had influence in acoustic and source-coding (audio compression) research. Both Krasner and Schroeder built upon the work of E. F. Zwicker, that in turn built on the fundamental research in the area from Bell Labs of Harvey Fletcher and his collaborators. A wide variety of audio compression algorithms, mostly (but not completely) perceptual were reported in a refereed journal, the Journal on Selected Areas in Communications,. That journal reported in Feb. 1988 on a wide range of established, working audio bit compression technologies, most of them using auditory masking as part of their fundamental design, and several showing real-time hardware implimentations.
Reference : http://en.wikipedia.org/wiki/Mp3