Before we talk about what MIDI is, let’s talk about what MIDI is not.
- MIDI is not a word…it is an acronym for Musical Instrument Digital Interface. When you see it spelled as midi, or midifile, the author is either a bad typist, or really doesn’t understand what MIDI is.
- MIDI is not a recording. MIDI is a data stream…a chain of instructions sent to a particular device telling it to do something. It could tell the device (usually a synth, or sound card) to play a particular note, or to stop playing notes, etc.
- MIDI is not a sound recording. A MIDI contains no sounds. It tells the connected devices to play the sounds.
I remember watching some of my favorite progressive rock bands back in the early 70’s. Some of those keyboard players lugged around a plethora of keyboards because each one contained certain sounds that they needed. (actually, the roadies lugged them around). The musicians and the manufacturers soon became frustrated and thought there must be a better way. So they got together to establish a way for electronic keyboards to communicate with each other. Thus MIDI was born.
In September of 1991 the MIDI Manufacturers Association (MMA) and the Japan MIDI Standards Committee (JMSC) adopted the "General MIDI System Level 1" specification (GM). The specification is designed to provide a minimum level of performance compatibility among MIDI instruments, and has helped pave the way for MIDI in the growing consumer and multimedia markets. MIDI was introduced in 1983. It was developed in cooperation between the major music industry electronic instrument manufacturers including Roland, Yamaha, Korg and others. No one ever dreamed the kinds of sounds that could be created and accessed using such a powerful communications protocol.
What’s General MIDI?
General MIDI is a standard adopted recently (comparatively) by many manufacturers. The original "problem" of MIDI is that if you took a MIDI file from one musician’s studio to another’s, they probably won’t assign the same instruments to the same patch # (Instrument number). So a piano part may be played as a drum, a violin becomes a trombone…and so on.
General MIDI is a set of rules such that the same patch # correspond to the same instruments. (eg: Patch 0 is always Grand Piano, Patch 40 = Violin) That is also the standard for Sound Cards too.
Roland’s GS Standard
When Warner New Media first proposed a General MIDI standard, most MMA members gave it little thought. As discussions proceeded, Roland listened and developed a sound module to meet the proposed specification. At the same NAMM show where the MMA ratified General MIDI Level 1, Roland showed their Sound Brush and Sound Canvas, a Standard MIDI File player and GM-compatible sound module. Some companies feel that General MIDI doesn’t go far enough, so Roland created a superset of General MIDI Level 1, which they call GS Standard. It obeys all the protocols and sound maps of General MIDI and adds many extra controllers and sounds.
Some of the controllers use Unregistered Parameter Numbers to give macro control over synth parameters such as envelope attack and decay rates. The new MIDI Bank Select message provides access to extra sounds (including variations on the stock sounds and a re-creation of the MT-32 factory patches). The programs in each bank align with the original 128 in General MIDI’s Instrument Patch Map, with eight banks housing related families. The GS Standard includes a "fall back" system. If the Sound Canvas receives a request for a bank/program number combination that does not exist, it will reassign it to the master instrument in that family. A set of Roland System Exclusive messages allows reconfiguration and customization of the sound module. This means that a Roland GS Standard sound module will correctly play back any song designed for General MIDI.
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