| MIDI stands for Musical Instrument Digital Interface.
A MIDI file doesn't contain actual audio data, but rather contains commands that let MIDI-capable synthesizers re-create a specific musical passage. The MIDI protocol has been used for years as a way for electronic musical instruments (like digital keyboards and sequencers) to communicate with each other.
Computer sound cards typically feature the ability to interpret MIDI files into music. Since they don't actually contain the music itself, but rather the commands used to re-create music, MIDI files are a lot smaller than audio files like MP3s, WMAs, or WAVs. MIDI files are small and manageable enough that it's not uncommon to find them embedded in web pages, adding a sonic element to the surfing experience. MIDI files usually appear with the ".MID" filename extension.
Musical Instrument Digital Interface, or MIDI, is an industry-standard protocol that defines each note precisely and concisely, allowing electronic musical instruments and computers to exchange data, or "talk", with each other. The MIDI standard was first proposed by Dave Smith in 1981 in a paper to the Audio Engineering Society and the MIDI Specification 1.0 was published in August 1983.
MIDI allows computers, synthesizers, sound cards and drum machines to control one another, and to exchange system information. Though modern computer sound cards are MIDI-compatible and capable of creating realistic instrument sounds, the fact that sound cards' MIDI synthesizers have historically produced sounds of dubious quality has tarnished the image of a general purpose computer as a MIDI instrument. This despite the fact that the MIDI specification itself has nothing to do with the quality of the sound produced which varies depending on the sound card used.
MIDI is almost directly responsible for bringing an end to the "wall of synthesizers" phenomenon in 1970s-80s rock music concerts, when musical keyboard performers were sometimes hidden behind banks of various instruments. Following the advent of MIDI, many synthesizers were released in rack-mount versions, enabling performers to control multiple instruments from a single keyboard. Another important effect of MIDI has been the development of hardware and computer-based sequencers, which can be used to record, edit and play back performances.
Synchronization of MIDI sequences is made possible by the use of MIDI timecode, an implementation of the SMPTE time code standard using MIDI messages, and MIDI timecode has become the standard for digital music synchronization.
A number of music file formats have been based on the MIDI bytestream. These formats are very compact; a file of only 10 kilobytes can produce a full minute of music.
How to convert MP3, CD, WAV to MIDI.