MPEG-1 audio layer 3

music, file format (MP3) A digital audio compressionalgorithm that acheives a compression factor of about twelve

while preserving sound quality. It does this by optimising

the compression according to the range of sound that people

can actually hear. MP3 is currently (July 1999) the most

powerful algorithm in a series of audio encoding standards

developed under the sponsorship of the Moving Picture ExpertsGroup (MPEG) and formalised by the International Organization

for Standardization (ISO).

MP3 is very different from Layer 2, using an additional MDCT

layer to increase frequency resolution. Its scale factor

groups are more optimised for the human ear, and it uses

nonlinear sample quantisation and Huffman coding.

MP3 files (filename extension ".mp3") can be downloaded from

many World-Wide Web sites and can be played using software

available for most operating systems (also downloadable),

e.g. Winamp for PC, MacAmp for Macintosh, and mpeg123 for

Unix.

MP3 files are usually downloaded completely before playing but

streaming MP3 is also possible. A program called a "ripper"

can be used to copy a selection from a music CD onto your

hard disk and another program called an encoder can convert

it to an MP3 file.

(2001-12-04)