Editing MIDI (section)

===Messages===
A MIDI message is an instruction that controls some aspect of the receiving device. A MIDI message consists of a status byte, which indicates the type of the message, followed by up to two data bytes that contain the parameters.<ref name="Brewster">Brewster, Stephen. "Nonspeech Auditory Output". ''The Human-Computer Interaction Handbook: Fundamentals, Evolving Technologies, and Emerging Applications''. Ed. Julie A. Jacko; Andrew Sears. Mahwah: Lawrence Erlbaum Associates, 2003. p.227</ref> MIDI messages can be ''channel messages'' sent on only one of the 16 channels and monitored only by devices on that channel, or ''system messages'' that all devices receive. Each receiving device ignores data not relevant to its function.<ref name="Gibbs" />{{rp|384|date=November 2012}} There are five types of message: Channel Voice, Channel Mode, System Common, System Real-Time, and System Exclusive.<ref>Hass, Jeffrey. "[http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI3.shtml Chapter Three: How MIDI works 3] {{webarchive|url=https://web.archive.org/web/20150619160322/http://www.indiana.edu/~emusic/etext/MIDI/chapter3_MIDI3.shtml |date=19 June 2015 }}". Indiana University Jacobs School of Music. 2010. Web. 13 August 2012.</ref>

Channel Voice messages transmit real-time performance data over a single channel. Examples include ''note-on'' messages which contain a MIDI note number that specifies the note's pitch, a velocity value that indicates how forcefully the note was played, and the channel number; ''note-off'' messages that end a note; program change messages that change a device's patch; and control changes that allow adjustment of an instrument's parameters. MIDI notes are numbered from 0 to 127 assigned to C<sub>−1</sub> to G<sub>9</sub>. This extends beyond the 88-note piano range from A<sub>0</sub> to C<sub>8</sub> and corresponds to a frequency range of 8.175799 to 12543.85&nbsp;Hz.{{efn|Assuming equal temperament and 440&nbsp;Hz A<sub>4</sub>}}

====System Exclusive messages {{anchor|SysEx}}====
System Exclusive ('''SysEx''') messages send information about a synthesizer's functions, rather than performance data such as which notes are being played and how loud. Because they can include functionality beyond what the MIDI standard provides, they are a major reason for the flexibility and longevity of the MIDI standard. Manufacturers use them to create proprietary messages that control their equipment more thoroughly than the limitations of standard MIDI messages.<ref name="Manning3" />{{rp|287|date=November 2012}}

The MIDI Manufacturers Association issues a unique identification number to MIDI companies.<ref>{{Cite web |title=Request SysEx ID |url=https://www.midi.org/request-sysex-id |url-status=live |archive-url=https://web.archive.org/web/20210923085555/https://www.midi.org/request-sysex-id |archive-date=2021-09-23 |access-date=2023-10-06 |website=[[MIDI Manufacturers Association]]}}</ref> These are included in SysEx messages, to ensure that only the specifically addressed device responds to the message, while all others know to ignore it. Many instruments also include a SysEx ID setting, so a controller can address two devices of the same model independently.<ref>Hass, Jeffrey. "[http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI9.shtml Chapter Three: How MIDI works 9] {{webarchive|url=https://web.archive.org/web/20150607074022/http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI9.shtml |date=7 June 2015 }}". Indiana University Jacobs School of Music. 2010. Web. 13 August 2012.</ref>

''Universal'' System Exclusive messages are a special class of SysEx messages used for extensions to MIDI that are not intended to be exclusive to one manufacturer.<ref>{{Cite web |title=MIDI 1.0 Universal System Exclusive Messages |url=https://www.midi.org/specifications-old/item/table-4-universal-system-exclusive-messages |url-status=live |archive-url=https://web.archive.org/web/20230721230039/https://www.midi.org/specifications-old/item/table-4-universal-system-exclusive-messages |archive-date=2023-07-21 |access-date=2023-10-06 |website=[[MIDI Manufacturers Association]]}}</ref>

====Implementation chart====
Devices typically do not respond to every type of message defined by the MIDI specification. The MIDI implementation chart was standardized by the MMA as a way for users to see what specific capabilities an instrument has, and how it responds to messages.<ref name="Huber 1991" />{{rp|231|date=November 2012}} A populated MIDI implementation chart is usually published as part of the documentation for MIDI devices.