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The Concept
The Algorithm
MP3: An Overview

The MPEG audio standard is a high-complexity, high-compression, and high audio quality algorithm. The Motion Pictures Experts Group (MPEG), a group that works on standards for both audio and video systems, saw the benefits of the digital representation of audio data. Its advantages include high immunity to noise (interference that destroys the integrity of signals), stability, reproducibility, and the efficient implementation of audio processing functions through a computer.

MPEG is a working group that was formed from the existing JPEG (Joint Photographic Experts Group) standard for bit reduction of still pictures. Its goal is to devise a suitable encoding scheme for transmitting moving pictures and sound over various broadcast links and recording them in standard digital storage media. Since moving pictures are often accompanied by sound, MPEG also defined a standard for encoding audio information. In 1992, a standard for audio and video encoding was devised known as MPEG-1.

MP3 stands for MPEG-1 Layer 3. Layers represent a family of coding algorithms. Layer 1 has the lowest complexity compared to the other layers. Layer 2 requires a more complex encoder and decoder and is directed more towards different applications. Thus, Layer 2 is more able than Layer 1 to remove the redundancy in the signal that takes up space. Layer 3 is again more complex and further reduces redundancy and relevance from the data. . The layers are backwards-compatible, which means that any software or hardware capable of decoding Layer 3 audio should also be able to decode Layers 1 and 2.

So why has MP3 emerged as the leading tool for Internet audio delivery? MPEG-1 Layer 3 is defined as an open standard, so the specification is available to anyone interested in implementing the standard. Since no single company owns the standard, public example source code is available and the format is well defined. Also, driven by the demand for professional use, many MP3 encoders and decoders are readily available for use. This simplifies and accelerates the adoption of MP3 technology. Additionally, the widespread increase in usage of computers fast enough to decode audio, as well as increasingly fast and widely available Internet access, has contributed to the embracing of MP3 music format.

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