1.2.1 MP3

Widespread digital encoding of music arrived with the introduction of the compact disk in 1982. However, the size of the resulting digital representation was large: the standard Compact Disk stored about one hour & twenty minutes worth of music in about seven hundred MiB (at a time when the typical hard drive could hold ten MiB). In 1989 the relevant standards body (the Moving Picture Experts Group, or MPEG) called for proposals for lossy audio compression algorithms. The fourteen propsals they received were eventually combined into three “layers”, each with a different set of trade-offs between quality, space, and computational complexity. “MPEG Audio Layer I” was the simplest, designed to enable real-time encoding on the hardware of the day. “MPEG Audio Layer II” provides higher quality than Layer I but offers computationally simpler decoding than Layer III. “MPEG Audio Layer III” (or MP3) provides good quality at lower bitrates than Layer II, albeit at the cost of greater computational complexity.

Layer three was primarily developed by the German company Fraunhofer IIS. The file extension .mp3 was selected as a result of an internal survey of researchers at Frauhofer. At a sampling rate of 128kbits/sec, MP3 needed about a megabyte per minute of music encoded; nearly one-tenth the size of CD audio.

At one MB per minute, given the size of consumer hard drives in the nineties, home users could easily store many MP3 tracks. The format found such universal application in the portable digital music players becoming available that they came to be known as “mp3 players”. With the network bandwidths available at the time, one could conveniently transmit MP3-encoded files across the internet, and even stream them.

Typically of technological history, the application responsible for the widespread adoption of MP3 was not the application for which it was designed. Applications for audio encoded by MP3 were intitially thought to be “musical transmission over ISDN telephone lines” and “voice announcement systems for local public transport”. Instead, the medium of choice for digital music became the ‘.mp3’ file.