What is an MP3?
“MP3”, the abbreviation for Mpeg2 audio layer 3, is a method of compressing audio.  It can reduce CD audio in size by a factor of eleven, while maintaining fairly high sound quality. It can also do this by operating on some principles concerning the range of human hearing. We cannot hear sounds above a certain frequency (think dog whistles), but CD audio contains all the frequencies of the music, whether or not you can hear them.  An MP3 encoder pinpoints the parts of the music that are trying to produce sounds we cannot hear, or higher frequencies, and rather indiscriminately gets rid of those frequencies. The quality and size of an MP3 depends chiefly on how indiscriminate the MP3 encoder is in removing frequencies. The more it removes, the smaller the file, but the worse it can sound, and vice versa. The information lost in an original audio file's evolution to an MP3 is irretrievable.

The WAV file format is the most widely supported sound format. The WAV file format will allow you to encode stereo and mono sounds, while specifying to what degree you wish to store the sounds. The WAV format is generally accepted by most every sound playing utility.  The WAV format is different from mp3s in that they are a much simpler format for storing audio files. Unlike mp3s, WAVs are uncompressed, files can be copied, coded, and stored, sans major alteration of the original product. Furthermore, where as WAV file format is compatible with practically all audio playing units, mp3s must be decompressed while playing, and therefore must be played specifically on a computer.

To make an MP3 in your very own home, most importantly, you would need a CD-ROM that supports ripping. "Ripping" is a really swank way of saying copying, compressing, or translating an audio file into an MP3.  A processor is required to compress the file, then an estimated 100 Mb or more of free space on hard disk is needed to hold it.  At least 16 megs of memory is recommended. (Adapted from "Ripping for MP3")

The quality of an MP3 is a reflection of certain elements.  The standard rate is 128 kbps, which uses approximately 1 Mb of hard disk space per minute of MP3 file. This allows for 1:12 compression; maximum sound quality with minimal disk space. Higher bit rates generally give higher sound quality as well as larger files, but different encoders have different effects. "A 4 minutes track, encoded with the codec at 128 kbps will occupy 3660 kb. The same file, encoded at 192 kbps, occupies 5500 kb. An increase by 50%" ("Ripping for MP3").

In the layer 3 file, mp3s store information about the author, artist, song names, etc. This information, MP3 IDTAG, helps label and identify the MP3 file, and can be edited by using an ID Tag editor. The ever so popular MP3 CDDB (CD Database) program allows the search for and retrieval of disc titles and track names from an internet database, granted adequate connection.

MP3s, CDs, minidisks, etc. are all different ways of storing audio data.  MP3s and minidisks use similar compression techniques. They both discard the upper-most and lower-most frequencies which the human ear cannot detect. CDs, however, store everything in raw, unprocessed form.

Created as part of a term project for SCEN103 at the University of Delaware All pages designed and best viewed at 800 x 600 resolution high color (16 bit)  Last updated May 23, 2000.  © 2000 Joseph Brobst, Ian Cosden, Patricia Jenkins, Garry Quinton, Deborah Watson, Univ. of Delaware