The importance of MP3 is made clear by some straightforward arithmetic. The music on a compact disc is encoded in such a way that a single second corresponds to approximately 176 KB of data, and a single three-minute song to approximately 32MB. In the mid-1990s, when it was not uncommon for a personal computer to have a total hard-drive capacity of only 500MB, it was therefore impossible to store even one album’s worth of music on the average home computer. And given the actual connection speed of a then-standard 56K dial-up modem, even a single album’s worth of music would have taken literally all day to transfer over the Internet.
Over the course of the early 1990s, several teams of audio engineers worked to develop, test and perfect the standard that would eventually gain the blessing of Motion Picture Experts Group (MPEG), a working group of the International Standardisation Organisation ISO. Their approach took advantage of certain physical and cognitive characteristics of human hearing, such as our inability to detect the quieter of two sounds played simultaneously. Using a “perceptual” compression method, engineers were able to eliminate more than 90 percent of the data in a standard CD audio file without compromising sound quality as perceived by the average listener using standard audio equipment.
Known formally as “MPEG-1 Audio Layer 3,” the technology in question was an efficient new format for the encoding of high-quality digital audio using a highly efficient data-compression algorithm. The brand-new MP3 format was given its name and its familiar “.mp3” file extension on this day in 1995. The very next year Worldspace Radio chose mp3 for audio coding. Suddenly, that digital copy of your favorite pop song took up only 2-3 MB on your hard-drive rather than 32MB, which in combination with the growth in average drive capacity and the increase in average Internet connection speed created the conditions for both the rampant, Winamp- and Napster-enabled copyright infringement of 1999-2000 and for the legal commercial distribution of digital music via the Internet.