MIDI standards, a brief history and explanation
Tttphe Music Instrument Digital Interface (MIDI) standard has been around for a long time. Although many of us still think of MIDI as a “newer” technology, Midi has been around longer than any student enrolled in their undergraduate, graduate, and for most, their doctoral programs!
The initial MIDI specification was developed in 1982 and various changes have been made over the course of its implementation. In the beginning, MIDI was not only revolutionary, but also fairly easy to use. Compared to the trials and tribulations of those who wrangled with synth technologies in the 1970s, MIDI was both simple and enabling -but, it was not without problems.
One of the major problems that plagued the initial MIDI 1982 standard was the lack of vendor consistent standards and cross-vendor interoperability of the MIDI devices (keyboards, sequencers, etc.) especially, with relation to the “sounds” or sound patches. If a MIDI file was programmed and saved on one type of synth then attempted to be played on a different manufacturers device, it did not sound remotely similar to the original. This was due to the lack of a universal, manufacturer independant “sound patch”. Simply put, a piano sound on one manufacturers device might be a trombone on others!
Another major problem, with the fledgling MIDI 1.0 standard, was individual keyboard manufactures would often have designated “percussion channels” assigned to different playback channels. This would cause a whole host of problems for the end-user and often created a completely “jumbled sounding” composition when played back with a different manufacturer’s MIDI keyboard device.
Perhaps the most irritating inconsistency among manufactures was the failure to label the keyboard notes the same way. A “middle c” on one manufacturer’s synth might be an entire octave above or below one played on a different manufacturers’. Most of these problems were fixed with adoption of the General MIDI standard in 1991 (also GM or GM1).
The General MIDI LOGO:
The General MIDIstandard corrected most of the concerns for MIDI users and implemented cross-manufacturer industry standards that allowed the musician to be able to create a composition on a one manufacturer’s synth and have a reasonable expectation for it to playback similarly on another’s model.
Some major advancements of GM1:
- All sound generating devices had to be able to support a minimum of 24 voicings or 16 voicings and 8 percussive voicings
- A minimum of 16 simultaneous channels (one voice or timbre per channel…a trumpet would be assigned to one channel and a flute on another, etc.) had to be able to send and receive simultaneously
- The first 128 sounds were standardized. This meant that if a flute sound was programmed using MIDI into a composition on one type of synth, a flute sound would be played back on different synth as well
- Channel 10 was allocated to be the percussion channel and 47 percussion sounds were standardized on this channel -each key played a different type of percussion sound
- “Middle C” was set to be note “60” on all devices
- Some of global parameter numbers were changed so that things like pitch bend, and tuning could be standardized as well
The General MIDI 2 Standard:
As the needs of musicians grew and the sophistication of the hardware increased, the MIDI standard matured as well. In 1999 the General MIDI 2 standard (GM2) was introduced to the public. Although there were MANY changes, especially to items like the Registered Parameter Numbers (RPN) and System Exclusive messages (SysEx), the average end-user immediatly noticed the following changes:
- The minimum number of simultaneous voicings increased to 32
- Channel 11 was now being indicated as a 2nd drum channel
- An additional 128 sounds were standardized bringing the total number to universal sounds to 256
- When recording MIDI, things like decay time, vibrato, and brightness could be saved and transferred from device to device and sound the same across each manufacturer’s device
The GM2 standard is still be updated and refined. The latest revision was in September of 2003. [Updated Note: In February 2007 a new version of the MIDI 2 standard was released to the public]
Prior to the adoption of General MIDI2 the two largest manufacturers, Roland and Yamaha were developing their own MIDI extension standards; they are known as the GS and XG standards respectively. Both companies continue to refine these standards to this day.
In addition to the MIDI, GM1 and GM2 standards, there are some other MIDI related standards or “flavors”. These include:
The General Midi Lite standard (GM Lite):
A new version of MIDI (reminiscent of GM1) was developed for mobile devices such as telephones and pagers. GM Lite supports only 16 simultaneous notes and a reduced set of other codes.
Scalable Polyphony MIDI Specification (SP-MIDI):
This specification was written in order to allow composers the ability to choose which sounds and/or notes could be dropped out if their composition is played back on an inferior MIDI device. For instance, a composition written in the GM2 standard could be reduced (MIDI-wise) to drop out the 2nd and 3rd parts of the instrumentation when played back on a device that only has the capabilities of GM1 or GM Lite.
MIDI Machine Control and MIDI Show Control (MMC and MSC):
These specifications allow MIDI messages to be used to control other devices. Devices such as multi-tracks, CD players and even lighting control boards can be controlled using this subset of the MIDI standard
For more information about MIDI you can visit the following sites: