Glossary
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MP3
MPEG-1, Layer 3 Audio (MP3) is a compressed digital audio file format. This format allows for near CD quality
sound, but at a fraction of the size of normal audio files. MP3 files encoded from CD-ROM may be compressed
to under 10 percent of their former size. This digital sound encoding and compression process was developed
by the Fraunhofer Institut fur Integrierte Schaltungen and Thomson Multimedia. MP3 uses perceptual audio
coding and psychoacoustic compression to remove all superfluous information–more specifically, the redundant
and irrelevant parts of a sound signal that the human ear doesn't hear. It also adds a Modified Discrete Cosine
Transform (MDCT) that implements a filter bank, increasing the frequency resolution 18 times higher than that
of layer 2. MP3 shrinks the original sound data from a CD-ROM with a bitrate of 1411.2 kilobits per one second
of stereo music by a factor of 12 down to 112-128kbps, without sacrificing sound quality. The MP3 encoding
process is well suited for the transfer of high quality audio files with small file size over telephone or ISDN lines,
and over the Internet.
WMA
Windows Media Audio (WMA) is the compressed audio format created by Microsoft as an alternative to MP3.
WMA offers comparable quality at greater file compression than MP3, enabling you to store more music on
your PC or portable player.
