Editing MIDI (section)

===General MIDI===
{{Main|General MIDI}}
[[File:GM Standard Drum Map on vertical keyboard.svg|alt=GM Standard Drum Map on the keyboard|thumb|457x457px|[[General MIDI#Percussion|General MIDI's Percussion Key Map]] specifies the percussion sound that a given note triggers. MIDI note numbers shown in parentheses next to their corresponding keyboard note.]]
MIDI allows the selection of an instrument's sounds through program change messages, but there is no guarantee that any two instruments have the same sound at a given program location.<ref name="Bello">Bello, Juan P. "[http://www.nyu.edu/classes/bello/FMT_files/10_MIDI_soundcontrol.pdf MIDI: sound control] {{webarchive|url=https://web.archive.org/web/20121120074709/http://www.nyu.edu/classes/bello/FMT_files/10_MIDI_soundcontrol.pdf |date=20 November 2012 }}". ''nyu.edu''. New York University. n.d. Web. 18 August 2012</ref> Program #0 may be a piano on one instrument, or a flute on another. The General MIDI (GM) standard was established in 1991, and provides a standardized sound bank that allows a Standard MIDI File created on one device to sound similar when played back on another. GM specifies a bank of 128 sounds arranged into 16 families of eight related instruments, and assigns a specific program number to each instrument.<ref>{{cite web |last1=Ialuna |first1=John |title=General MIDI (GM) Level 1 Sound Set |url=https://www.midi.com.au/gm-1-soundset/ |website=Hit Trax MIDI Files |access-date=15 August 2018 |archive-date=15 August 2018 |archive-url=https://web.archive.org/web/20180815164219/https://www.midi.com.au/gm-1-soundset/ |url-status=live }}</ref> Any given program change selects the same instrument sound on any GM-compatible instrument.<ref>"[http://academic.pgcc.edu/~njudy/mt/MIDI/gm.html General MIDI Standard] {{webarchive|url=https://web.archive.org/web/20130120153144/http://academic.pgcc.edu/~njudy/mt/MIDI/gm.html |date=20 January 2013 }}". ''pgcc.edu''. Prince George's Community College. n.d. Web.</ref> Percussion instruments are placed on channel 10, and a specific MIDI note value is mapped to each percussion sound. 

The GM standard eliminates variation in note mapping. Some manufacturers had disagreed over what note number should represent middle C, but GM specifies that note number 69 plays [[A440 (pitch standard)|A440]], which in turn fixes middle C as note number 60.

GM-compliant devices must offer 24-note polyphony.<ref>{{cite web |url=http://www.harfesoft.de/aixphysik/sound/midi/pages/genmidi.html |title="General MIDI Standard". ''www.harfesoft.de''. n.p. n.d. Web |publisher=Harfesoft.de |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20120828013530/http://www.harfesoft.de/aixphysik/sound/midi/pages/genmidi.html |archive-date=28 August 2012  }}</ref> GM-compatible devices are required to respond to velocity, aftertouch, and pitch bend, to be set to specified default values at startup, and to support certain controller numbers such as for [[sustain pedal]], and Registered Parameter Numbers (RPNs).<ref>Glatt, Jeff. "[http://home.roadrunner.com/~jgglatt/tutr/gm.htm General MIDI] {{webarchive|url=https://web.archive.org/web/20121023090423/http://home.roadrunner.com/~jgglatt/tutr/gm.htm |date=23 October 2012 }}". ''The MIDI Technical Fanatic's Brainwashing Center''. n.p. n.d. Web. 17 August 2012</ref>

A simplified version of GM, called ''GM Lite'', is used for devices with limited processing power.<ref name="Bello" /><ref>{{Cite web |title=General MIDI Lite |url=https://www.midi.org/specifications-old/item/general-midi-lite |access-date=2023-12-15 |website=www.midi.org |archive-date=15 December 2023 |archive-url=https://web.archive.org/web/20231215035132/https://www.midi.org/specifications-old/item/general-midi-lite |url-status=dead }}</ref>