standard MIDI format (SMF)
The standard MIDI file format( SMF) has evolved from the original MIDI format and is composed of chunks, which makes it very flexible. Events are time-stamped in SMF format for playback.
The SMF format is not a format under which audio files are stored, like the Waveform Audio File(WAV) or the Audio Interchange File Format( AIFF), it rather describes a list of events with which a sound card or playback device can generate the corresponding sound. As a result, MIDI files are much smaller than digital audio files, and the events and sounds are editable, allowing the music to be rearranged, edited, and composed interactively.
MIDI data is used to give instructions as to which sound is to be produced at what time by which instrument, combining pitch, tone duration and velocity to create a composition. Synthesizersound cards can use these control instructions to create sound patterns. Control instructions are numeric values and special MIDI numbers that specify pitch. MIDI data is descriptive data that specifies which instrument should play which note at what volume for how long. To avoid incompatibilities between different devices, General-MIDI defined timbres as numeric digits.
The first MIDI format, specified as early as 1983, did not include all possible MIDI tones and also did not sufficiently take into account the possibilities of electronic music. This led to the fact that over the years the original MIDI specification was considerably extended in terms of additional control messages. These include MIDI Machine Control( MTC), MIDI Show Control, MIDI Time Control, General MIDI( GM-MIDI), Downloadable Sounds( DLS) and Scalable Polyphony MIDI( SP-MIDI).