View source for MIDI

{{Short description|Connection standard for electronic musical instruments}}
{{Other uses}}
{{Technical|date=November 2018}}
{{Use American English|date=August 2020}}
{{Use mdy dates|date=March 2025}}
{{Infobox protocol
| standard  = MIDI Standard
| developer = [[MIDI Manufacturers Association|MMA]]
| introdate = {{Start date and age|1983|02|01}}
| newer     = [[MIDI 2.0]]
| range     = Up to 15 [[meters]] (50 [[Foot (unit)|feet]])
| hardware  = [[Serial transmission]] at 31,250 baud
| connector = [[DIN connector|5‑pin DIN]] (with modern alternatives: [[USB]], [[Bluetooth]], [[Ethernet]])
| industry  = [[Music technology (electronic and digital)]]
| name      = Musical Instrument Digital Interface
| website   = [https://www.midi.org https://www.midi.org]
| image     = MIDI LOGO.svg
}}

[[File:Ented, Nokturn a-moll - Jesienny.ogg|thumb|Example of music created in MIDI format]]
[[File:Synth rack @ Choking Sun Studio.jpg|thumb|alt=Several rack-mounted synthesizers that share a single controller|Using MIDI, a single controller (often a musical keyboard, as pictured here) can play multiple electronic instruments, which increases the portability and flexibility of stage setups. This system fits into a single rack case, but before the advent of MIDI, it would have required four separate full-size keyboard instruments, plus outboard mixing and [[effects unit]]s.]]

'''Musical Instrument Digital Interface''' ({{IPAc-en|ˈ|m|ɪ|d|i}}; '''MIDI''') is an American-Japanese [[technical standard]] that describes a [[communication protocol]], [[Digital electronics|digital interface]], and [[electrical connector]]s that connect a wide variety of [[electronic musical instrument]]s, [[computer]]s, and related audio devices for playing, editing, and recording music.<ref>{{citation |last=Swift |first=Andrew. |url=http://www.doc.ic.ac.uk/~nd/surprise_97/journal/vol1/aps2/ |title=A brief Introduction to MIDI |work=SURPRISE |publisher=Imperial College of Science Technology and Medicine |date=May 1997 |access-date=22 August 2012 |archive-url=https://web.archive.org/web/20120830211425/http://www.doc.ic.ac.uk/~nd/surprise_97/journal/vol1/aps2/ |archive-date=30 August 2012}}</ref> A single MIDI cable can carry up to sixteen channels of MIDI data, each of which can be routed to a separate device. Each interaction with a key, button, knob or slider is converted into a MIDI event, which specifies musical instructions, such as a note's [[Pitch (music)|pitch]], timing and velocity. One common MIDI application is to play a MIDI [[Electronic keyboard|keyboard]] or other controller and use it to trigger a digital [[sound module]] (which contains synthesized musical sounds) to generate sounds, which the audience hears produced by a [[keyboard amplifier]]. MIDI data can be transferred via MIDI or [[USB]] cable, or recorded to a [[Music sequencer|sequencer]] or [[digital audio workstation]] to be edited or played back.<ref name="Huber 1991"/>

MIDI also defines a [[file format]] that stores and exchanges the data. Advantages of MIDI include small [[file size]], ease of modification and manipulation and a wide choice of electronic instruments and [[synthesizer]] or [[Sampler (musical instrument)|digitally sampled sounds]].<ref>{{cite web|url=http://www.instructables.com/id/What-is-MIDI/|title=What is MIDI?|access-date=31 August 2016|url-status=live|archive-url=http://webarchive.loc.gov/all/20160616112709/http://www.instructables.com/id/What-is-MIDI/|archive-date=16 June 2016}}</ref>{{rp|4|date=November 2012}} A MIDI recording of a performance on a keyboard could sound like a piano or other keyboard instrument; however, since MIDI records the messages and information about their notes and not the specific sounds, this recording could be changed to many other sounds, ranging from synthesized or sampled guitar or flute to full orchestra.

Before the development of MIDI, electronic musical instruments from different manufacturers could generally not communicate with each other. This meant that a musician could not, for example, plug a Roland keyboard into a Yamaha synthesizer module. With MIDI, any MIDI-compatible keyboard (or other controller device) can be connected to any other MIDI-compatible sequencer, sound module, [[drum machine]], synthesizer, or computer, even if they are made by different manufacturers.

MIDI technology was standardized in 1983 by a panel of music industry representatives and is maintained by the [[MIDI Manufacturers Association]] (MMA). All official MIDI standards are jointly developed and published by the MMA in Los Angeles, and the MIDI Committee of the [[Association of Musical Electronics Industry]] (AMEI) in Tokyo. In 2016, the MMA established The MIDI Association (TMA) to support a global community of people who work, play, or create with MIDI.<ref>{{cite web|url=http://www.emusician.com/gear/1332/the-midi-association-launches-at-namm-2016/56183|title=The MIDI Association Launches at NAMM 2016|first=Electronic Musician – featuring gear reviews, audio tutorials, loops and|last=samples|access-date=31 August 2016|url-status=live|archive-url=https://web.archive.org/web/20161014220505/http://www.emusician.com/gear/1332/the-midi-association-launches-at-namm-2016/56183|archive-date=14 October 2016}}</ref>

{{TOC limit|3}}

==History==
In the early 1980s, there was no [[standardized]] means of synchronizing [[electronic musical instrument]]s manufactured by different companies.<ref name="chadab5100">{{cite journal|last=Chadabe|first=Joel|author-link=Joel Chadabe|date=1 May 2000|title=Part IV: The Seeds of the Future|url=http://www.emusician.com/gear/0769/the-electronic-century-part-iv-the-seeds-of-the-future/145415|journal=Electronic Musician|publisher=Penton Media|volume=XVI|issue=5|archive-url=https://web.archive.org/web/20120928230435/http://www.emusician.com/gear/0769/the-electronic-century-part-iv-the-seeds-of-the-future/145415|archive-date=28 September 2012}}</ref> Manufacturers had their own proprietary standards to synchronize instruments, such as [[CV/gate]], [[DIN sync]] and [[Digital Control Bus]] (DCB).<ref name=":152">{{Cite book|last=Kirn|first=Peter|url=https://books.google.com/books?id=IbtJAgAAQBAJ&q=%22mark+vail%22+808&pg=PT72|title=Keyboard Presents the Evolution of Electronic Dance Music|date=2011|publisher=Backbeat Books|isbn=978-1-61713-446-3|archive-url=https://web.archive.org/web/20170201235744/https://books.google.co.uk/books?id=IbtJAgAAQBAJ&pg=PT72&lpg=PT72&dq=%22mark+vail%22+808&source=bl&ots=dOOpEyQGfI&sig=nPF6yAIeQlupw3Pw0Drg6LE34r4&hl=en&sa=X&ved=0ahUKEwir3b7qhsfRAhUFJcAKHfSNCyMQ6AEIHzAB#v=onepage&q=%22mark%20vail%22%20808&f=false|archive-date=1 February 2017|url-status=live}}</ref> [[Ikutaro Kakehashi]], the president of [[Roland Corporation|Roland]], felt the lack of standardization was limiting the growth of the electronic music industry.<ref name=":152" /> In June 1981, he proposed developing a standard to the [[Oberheim Electronics]] founder [[Tom Oberheim]],<ref name="chadab5100" /> who had developed his own proprietary interface, the Oberheim Parallel Bus.<ref name=":02">{{Cite news|url=http://www.factmag.com/2017/04/02/ikutaro-kakehashi-life/|title=The life and times of Ikutaro Kakehashi, the Roland pioneer modern music owes everything to|date=2 April 2017|work=FACT Magazine: Music News, New Music.|access-date=6 September 2018|language=en-US|archive-date=3 April 2017|archive-url=https://web.archive.org/web/20170403005512/http://www.factmag.com/2017/04/02/ikutaro-kakehashi-life/|url-status=live}}</ref>

Kakehashi felt that Oberheim's system was too cumbersome, and spoke to [[Dave Smith (engineer)|Dave Smith]], the president of [[Sequential Circuits]], about creating a simpler, cheaper alternative.<ref name=":02" /> While Smith discussed the concept with American companies, Kakehashi discussed it with Japanese companies [[Yamaha Corporation|Yamaha]], [[Korg]] and [[Kawai Musical Instruments|Kawai]].<ref name="chadab5100" /> Representatives from all companies met to discuss the idea in October.<ref name="chadab5100" /> Initially, only Sequential Circuits and the Japanese companies were interested.<ref name=":32">{{cite web|url=https://www.midi.org/midi-articles/historical-early-midi-documents-uncovered|title=Historical Early MIDI Documents Uncovered|website=www.midi.org|language=en-gb|access-date=18 January 2020|archive-date=29 September 2020|archive-url=https://web.archive.org/web/20200929112751/https://www.midi.org/midi-articles/historical-early-midi-documents-uncovered|url-status=live}}</ref> [[File:Dave Smith at Sequential booth - 2 - 2015 NAMM Show.jpg|thumb|Dave Smith (right), one of the creators of MIDI]]Using Roland's DCB as a basis,<ref name=":152" /> Smith and Sequential Circuits engineer Chet Wood devised a universal interface to allow communication between equipment from different manufacturers. Smith and Wood proposed this standard in a paper, ''Universal Synthesizer Interface,''<ref>{{Cite journal|last1=Smith|first1=Dave|last2=Wood|first2=Chet|date=1 October 1981|title=The 'USI', or Universal Synthesizer Interface|url=http://www.aes.org/e-lib/browse.cfm?elib=11909|url-access=subscription|language=en|website=Audio Engineering Society|access-date=18 January 2020|archive-date=5 August 2020|archive-url=https://web.archive.org/web/20200805050636/https://www.aes.org/e-lib/browse.cfm?elib=11909|url-status=live}}</ref> at the [[Audio Engineering Society]] show in October 1981.<ref name=":2">{{cite web |title=MIDI History:Chapter 6-MIDI Is Born 1980–1983 |url=https://www.midi.org/midi-articles/midi-history-chapter-6-midi-begins-1981-1983 |access-date=3 January 2023 |website=www.midi.org |language=en-gb |archive-date=3 January 2023 |archive-url=https://web.archive.org/web/20230103182245/https://www.midi.org/midi-articles/midi-history-chapter-6-midi-begins-1981-1983 |url-status=live }}</ref><ref name="Huber 19913">{{cite book|last=Huber|first=David Miles|url=https://archive.org/details/midimanual00hube|title=The MIDI Manual|date=1991|publisher=SAMS|isbn=978-0-672-22757-8|location=Carmel, Indiana}}</ref>{{rp|4|date=November 2012}} The standard was discussed and modified by representatives of Roland, Yamaha, Korg, Kawai, and Sequential Circuits.<ref name="chadab5100"/><ref name="Holmes3">Holmes, Thom. ''Electronic and Experimental Music: Pioneers in Technology and Composition''. New York: Routledge, 2003</ref>{{rp|20|date=November 2012}} Kakehashi favored the name Universal Musical Interface (UMI), pronounced ''you-me'',<ref name=":02" /> but Smith felt this was "a little corny".<ref name=":1">{{Cite news|url=https://www.keyboardmag.com/gear/dave-smith-the-synth-design-icon-talks-analog-midi-and-more|title=Dave Smith|work=KeyboardMag|access-date=20 October 2018|language=en-us|archive-date=20 October 2018|archive-url=https://web.archive.org/web/20181020095110/https://www.keyboardmag.com/gear/dave-smith-the-synth-design-icon-talks-analog-midi-and-more|url-status=live}}</ref> However, he liked the use of ''instrument'' instead of ''synthesizer'', and proposed ''Musical Instrument Digital Interface'' (MIDI).<ref name=":1" /><ref name="Huber 19913" />{{rp|4|date=November 2012}} [[Robert Moog]], the president of [[Moog Music]], announced MIDI in the October 1982 issue of ''[[Keyboard (magazine)|Keyboard]]''.<ref name="Manning3">Manning, Peter. ''Electronic and Computer Music''. 1985. Oxford: Oxford University Press, 1994. Print.</ref>{{rp|276|date=November 2012}}

At the 1983 Winter [[NAMM Show]], Smith demonstrated a MIDI connection between [[Sequential Circuits Prophet-5|Prophet 600]] and [[Roland Jupiter-6|Roland JP-6]] synthesizers. The MIDI specification was published in August 1983.<ref name="chadab5100" /> The MIDI standard was unveiled by Kakehashi and Smith, who received [[Technical Grammy Award]]s in 2013 for their work.<ref>{{cite web|url=http://www.grammy.com/news/technical-grammy-award-ikutaro-kakehashi-and-dave-smith|title=Technical GRAMMY Award: Ikutaro Kakehashi And Dave Smith|archive-url=https://web.archive.org/web/20160822073641/http://www.grammy.com/news/technical-grammy-award-ikutaro-kakehashi-and-dave-smith|archive-date=22 August 2016|access-date=31 August 2016|url-status=live}}</ref><ref>{{cite web|url=http://www.grammy.com/videos/technical-grammy-award-recipients-ikutaro-kakehashi-and-dave-smith-at-special-merit-awards|title=Ikutaro Kakehashi, Dave Smith: Technical GRAMMY Award Acceptance|date=9 February 2013|archive-url=https://web.archive.org/web/20141209022049/http://www.grammy.com/videos/technical-grammy-award-recipients-ikutaro-kakehashi-and-dave-smith-at-special-merit-awards|archive-date=9 December 2014|access-date=31 August 2016|url-status=live}}</ref><ref>{{cite book|last1=Vail|first1=Mark|title=The Synthesizer|date=2014|publisher=Oxford University Press|isbn=978-0-19-539481-8|location=New York|page=56}}</ref> In 1983, the first instruments were released with MIDI, the [[Roland Jupiter-6]] and the Prophet 600. In 1983, the first MIDI [[drum machine]], the [[Roland TR-909]],<ref name="russ p66">{{cite book |url=https://books.google.com/books?id=_W9Ek2LmPNMC&pg=PA66 |archive-url=https://web.archive.org/web/20171026003043/https://books.google.co.uk/books?id=_W9Ek2LmPNMC&pg=PA66 |archive-date=26 October 2017 |url-status=live  |title=Sound Synthesis and Sampling |author=Martin Russ |isbn=0-240-51692-3 |page=66|year=2004 | publisher=Taylor & Francis }}</ref><ref>{{cite book |last=Butler |first=Mark Jonathan |title=Unlocking the Groove: Rhythm, Meter, and Musical Design in Electronic Dance Music |publisher=Indiana University Press |date=2006 |isbn=0-2533-4662-2 |page=[https://archive.org/details/unlockinggroover00butl/page/64 64] |url=https://archive.org/details/unlockinggroover00butl/page/64 }}</ref> and the first MIDI [[music sequencer|sequencer]], the Roland MSQ-700, were released.<ref>{{cite web |url=https://www.roland.com/ca/company/history/ |title=Roland - Company - History - History |access-date=17 May 2017 |url-status=live |archive-url=https://web.archive.org/web/20170712075811/https://www.roland.com/ca/company/history/ |archive-date=12 July 2017 }}</ref>

The MIDI Manufacturers Association (MMA) was formed following a meeting of "all interested companies" at the 1984 Summer NAMM Show in Chicago. The MIDI 1.0 Detailed Specification was published at the MMA's second meeting at the 1985 Summer NAMM Show. The standard continued to evolve, adding standardized song files in 1991 ([[General MIDI]]) and adapted to new connection standards such as [[USB]] and [[FireWire]]. In 2016, the MIDI Association was formed to continue overseeing the standard.<ref name=":32" /> In 2017, an abridged version of MIDI 1.0 was published as an international standard [[IEC]] 63035.<ref>{{cite web |title=IEC 63035:2017 {{!}} IEC |url=https://webstore.iec.ch/en/publication/31626 |website=webstore.iec.ch |publisher=International Electrotechnical Commission (IEC) |access-date=5 November 2024}}</ref> An initiative to create a 2.0 standard was announced in January 2019.<ref name="MIDI2Prototyping">{{cite web|title=The MIDI Manufacturers Association (MMA) and the Association of Music Electronics Industry (AMEI) announce MIDI 2.0™ Prototyping|url=https://www.midi.org/articles-old/the-midi-manufacturers-association-mma-and-the-association-of-music-electronics-industry-amei-announce-midi-2-0tm-prototyping|website=www.midi.org|access-date=20 January 2019|archive-date=10 February 2019|archive-url=https://web.archive.org/web/20190210030409/https://www.midi.org/articles-old/the-midi-manufacturers-association-mma-and-the-association-of-music-electronics-industry-amei-announce-midi-2-0tm-prototyping|url-status=dead}}</ref> The MIDI 2.0 standard was introduced at the 2020 Winter NAMM Show.<ref name="midi2.0">{{cite web|title=An Update to a 37-Year-Old Digital Protocol Could Profoundly Change the Way Music Sounds|url=https://qz.com/1788828/how-will-midi-2-0-change-music/|last=Kopf|first=Dan|date=30 January 2020|publisher=[[Quartz (website)|Quartz]]|access-date=3 February 2020|archive-date=2 February 2020|archive-url=https://web.archive.org/web/20200202012719/https://qz.com/1788828/how-will-midi-2-0-change-music/|url-status=live}}</ref>

The [[BBC]] cited MIDI as an early example of [[open-source]] technology. Smith believed MIDI could only succeed if every manufacturer adopted it, and so "we had to give it away".<ref>{{Cite news |date=2012-11-28 |title=How MIDI changed the world of music |language=en-GB |work=[[BBC News]] |url=https://www.bbc.com/news/technology-20425376 |access-date=2022-07-04 |archive-date=27 April 2019 |archive-url=https://web.archive.org/web/20190427220431/https://www.bbc.com/news/technology-20425376 |url-status=live }}</ref>

=== Impact ===
MIDI's appeal was originally limited to professional musicians and [[record producer]]s who wanted to use electronic instruments in the production of [[popular music]]. The standard allowed different instruments to communicate with each other and with computers, and this spurred a rapid expansion of the sales and production of electronic instruments and music software.<ref name="Holmes3" />{{rp|21|date=November 2012}} This interoperability allowed one device to be controlled from another, which reduced the amount of hardware musicians needed.<ref>{{cite journal|last=Paul|first=Craner|title=New Tool for an Ancient Art: The Computer and Music|journal=Computers and the Humanities|date=Oct 1991|volume=25|issue=5|pages=308–309|jstor=30204425|doi=10.1007/bf00120967|s2cid=60991034}}</ref> MIDI's introduction coincided with the [[History of computing hardware (1960s–present)|dawn of the personal computer era]] and the introduction of [[Sampler (musical instrument)|samplers]] and [[digital synthesizer]]s.<ref>Macan, Edward. ''Rocking the Classics: English Progressive Rock and the Counterculture''. New York: Oxford University Press, 1997. p.191</ref> The creative possibilities brought about by MIDI technology are credited for helping revive the music industry in the 1980s.<ref>Shuker, Roy. ''Understanding Popular Music''. London: Routledge, 1994. p.286</ref>

MIDI introduced capabilities that transformed the way many musicians work. [[MIDI sequencing]] makes it possible for a user with no notation skills to build complex arrangements.<ref>Demorest, Steven M. ''Building Choral Excellence: Teaching Sight-Singing in the Choral Rehearsal''. New York: Oxford University Press, 2003. p. 17</ref> A musical act with as few as one or two members, each operating multiple MIDI-enabled devices, can deliver a performance similar to that of a larger group of musicians.<ref>Pertout, Andrian. ''[http://www.pertout.com/Midi.htm Mixdown Monthly] {{webarchive|url=https://web.archive.org/web/20120504055022/http://www.pertout.com/Midi.htm |date=4 May 2012 }}'', #26. 26 June 1996. Web. 22 August 2012</ref> The expense of hiring outside musicians for a project can be reduced or eliminated,<ref name="Huber 1991"/>{{rp|7|date=November 2012}} and complex productions can be realized on a system as small as a synthesizer with integrated keyboard and sequencer.

MIDI also helped establish [[home recording]]. By performing [[preproduction]] in a home environment, an artist can reduce recording costs by arriving at a recording studio with a partially completed song.<ref name="Huber 1991" />{{rp|7–8|date=November 2012}} In 2022, the ''[[The Guardian|Guardian]]'' wrote that MIDI remained as important to music as [[USB]] was to computing, and represented "a crucial value system of cooperation and mutual benefit, one all but thrown out by today's major tech companies in favour of captive markets". In 2005, Smith's MIDI Specification was inducted into the [[TECnology Hall of Fame]], an honor given to "products and innovations that have had an enduring impact on the development of audio technology."<ref>{{cite web|title=TECnology Hall of Fame, 2005|url=http://legacy.tecawards.org/tec/05TECnologyHOFdetails.html|website=TECawards.org|date=2005|access-date=December 12, 2024}}</ref> As of 2022, Smith's original MIDI design was still in use.<ref>{{cite web |last=Stokes |first=William |date=2022-06-03 |title=Dave Smith: the synth genius who made pop's instruments work in harmony |url=https://www.theguardian.com/music/2022/jun/03/dave-smith-synth-genius-pop-madonna-radiohead |access-date=2022-06-05 |website=[[The Guardian]] |language=en}}</ref>

==Applications==

===Instrument control===
MIDI was invented so that electronic or digital musical instruments could communicate with each other and so that one instrument can control another. For example, a MIDI-compatible sequencer can trigger beats produced by a drum [[sound module]]. Analog synthesizers that have no digital component and were built prior to MIDI's development can be retrofitted with kits that convert MIDI messages into analog control voltages.<ref name="Manning3" />{{rp|277|date=November 2012}} When a note is played on a MIDI instrument, it generates a digital MIDI message that can be used to trigger a note on another instrument.<ref name="Huber 1991" />{{rp|20|date=November 2012}} The capability for remote control allows full-sized instruments to be replaced with smaller sound modules, and allows musicians to combine instruments to achieve a fuller sound, or to create combinations of synthesized instrument sounds, such as acoustic piano and strings.<ref name="Why">Lau, Paul. "[http://www.highbeam.com/doc/1P3-1610624011.html Why Still MIDI?]."{{webarchive|url=https://web.archive.org/web/20130502161431/http://www.highbeam.com/doc/1P3-1610624011.html |date=2 May 2013 }} Canadian Musician. Norris-Whitney Communications Inc. 2008.</ref> MIDI also enables other instrument parameters (volume, effects, etc.) to be controlled remotely.

Synthesizers and samplers contain various tools for shaping an electronic or digital sound. [[Filter (signal processing)|Filters]] adjust [[timbre]], and envelopes automate the way a sound evolves over time after a note is triggered.<ref>{{cite magazine |last=Sasso |first=Len |url=http://www.emusician.com/news/0766/sound-programming-101/145154 |title=Sound Programming 101 |archive-url=https://web.archive.org/web/20120317104859/http://www.emusician.com/news/0766/sound-programming-101/145154 |archive-date=17 March 2012 |magazine=Electronic Musician |publisher=NewBay Media |date=13 October 2011}}</ref> The frequency of a filter and the envelope attack (the time it takes for a sound to reach its maximum level), are examples of synthesizer [[parameter]]s, and can be controlled remotely through MIDI. Effects devices have different parameters, such as delay feedback or reverb time. When a MIDI continuous controller number (CCN) is assigned to one of these parameters, the device responds to any messages it receives that are identified by that number. Controls such as knobs, switches, and pedals can be used to send these messages. A set of adjusted parameters can be saved to a device's internal memory as a ''patch'', and these patches can be remotely selected by MIDI program changes.{{efn|The MIDI standard allows selection of 128 different programs, but devices can provide more by arranging their patches into banks of 128 programs each and combining a program change message with a bank select message.}}<ref>{{cite magazine |last=Anderton |first=Craig |url=http://www.soundonsound.com/sos/1995_articles/may95/midiforguitarists.html |title=MIDI For Guitarists: A Crash Course In MIDI Effects Control |archive-url=https://web.archive.org/web/20120110075506/http://www.soundonsound.com/sos/1995_articles/may95/midiforguitarists.html |archive-date=10 January 2012 |magazine=[[Sound on Sound]] |publisher=SOS Publications |date=May 1995}}</ref>

===Composition===
{{Listen
| filename     = Drum sample.mid
| title        = Drum sample 1
| description  = Drum sample 1
| filename2    = Drum sample2.mid
| title2       = Drum sample 2
| description2 = Drum sample 2
| filename3    = Bass sample.mid
| title3       = Bass sample 1
| description3 = Bass sample 1
| filename4    = Bass sample2.mid
| title4       = Bass sample 2
| description4 = Bass sample 2
| filename5    = MIDI sample.mid
| title5       = Combination
| description5 = A combination of the previous four files, with [[piano]], [[jazz guitar]], a [[hi-hat]] and four extra [[Bar (music)|measures]] added to complete the short song, in [[A minor]]
}}

MIDI events can be sequenced with [[List of MIDI editors and sequencers|computer software]], or in specialized hardware [[music workstation]]s. Many [[digital audio workstation]]s (DAWs) are specifically designed to work with MIDI as an integral component. MIDI [[piano roll]]s have been developed in many DAWs so that the recorded MIDI messages can be easily modified.<ref>{{cite web|title=Digital audio workstation – Intro |url=http://homerecording.guidento.com/daw.htm |archive-date=10 January 2012 |archive-url=https://web.archive.org/web/20120110031303/http://homerecording.guidento.com/daw.htm }}</ref>{{Better source needed|date=August 2012}} These tools allow composers to audition and edit their work much more quickly and efficiently than did older solutions, such as [[multitrack recording]].{{Citation needed|date=July 2022}} Compositions can be programmed for MIDI that are impossible for human performers to play.<ref>{{cite web |last=Forbes |first=Peter |date=2002-03-14 |title=PCs hit the write note |url=http://www.theguardian.com/technology/2002/mar/14/onlinesupplement2 |access-date=2022-07-01 |website=[[The Guardian]] |language=en}}</ref>

Because a MIDI performance is a sequence of commands that create sound, MIDI recordings can be manipulated in ways that audio recordings cannot. It is possible to change the key, instrumentation or tempo of a MIDI arrangement,<ref name="Brewster" />{{rp|227|date=November 2012}} and to reorder its individual sections,<ref>Campbell, Drew. ""Click, Click. Audio" ''Stage Directions''. Vol. 16, No. 3. Mar 2003.</ref> or even edit individual notes. The ability to compose ideas and quickly hear them played back enables composers to experiment.<ref name="Muse">McCutchan, Ann. ''The Muse That Sings: Composers Speak about the Creative Process''. New York: Oxford University Press, 1999. p. 67-68,72</ref>{{rp|175|date=November 2012}}

[[Algorithmic composition]] programs provide computer-generated performances that can be used as song ideas or accompaniment.<ref name="Huber 1991" />{{rp|122|date=November 2012}}

Some composers may take advantage of the standard, portable set of commands and parameters in MIDI 1.0 and [[General MIDI]] (GM) to share musical data files among various electronic instruments. The data composed via the sequenced MIDI recordings can be saved as a ''standard MIDI file'' (SMF), digitally distributed, and reproduced by any computer or electronic instrument that also adheres to the same MIDI, GM, and SMF standards. MIDI data files are much smaller than corresponding recorded [[audio file]]s.{{Citation needed|date=July 2022}}

===Use with computers===
{{See also|Comparison of MIDI standards|Computer music}}

The [[personal computer]] market stabilized at the same time that MIDI appeared, and computers became a viable option for music production.<ref name="Manning3" />{{rp|324|date=November 2012}} In 1983 computers started to play a role in mainstream music production.<ref name="russ2012"/> In the years immediately after the 1983 ratification of the MIDI specification, MIDI features were adapted to several early computer platforms. The [[Yamaha CX5M]] introduced MIDI support and [[Music sequencer|sequencing]] in an [[MSX]] system in 1984.<ref name="casabona"/>

The spread of MIDI on home computers was largely facilitated by [[Roland Corporation]]'s [[MPU-401]], released in 1984, as the first MIDI-equipped [[sound card]], capable of MIDI sound processing<ref name="emusician-mpu"/> and sequencing.<ref>{{cite web|url=http://www.piclist.com/techref/io/serial/midi/mpu.html|archive-url=https://web.archive.org/web/20170506080336/http://www.piclist.com/techref/io/serial/midi/mpu.html|title=Programming the MPU-401|archive-date=6 May 2017|website=www.piclist.com}}</ref><ref>[https://ftp.oldskool.org/pub/drivers/Roland/MPU-401%20technical%20reference%20manual.pdf MIDI PROCESSING UNIT MPU-401 TECHNICAL REFERENCE MANUAL], [[Roland Corporation]]</ref> After Roland sold MPU [[sound chip]]s to other sound card manufacturers,<ref name="emusician-mpu"/> it established a universal standard MIDI-to-PC interface.<ref>Peter Manning (2013), [https://books.google.com/books?id=ryet1i-8OlYC ''Electronic and Computer Music''] {{webarchive|url=https://web.archive.org/web/20171026002807/https://books.google.co.uk/books?id=ryet1i-8OlYC |date=26 October 2017 }}, page 319, [[Oxford University Press]]</ref> The widespread adoption of MIDI led to computer-based [[Comparison of MIDI editors and sequencers|MIDI software]] being developed.<ref name="russ2012"/> Soon after, a number of platforms began supporting MIDI, including the [[Apple II]], [[Macintosh]], [[Commodore 64]], [[Amiga]], [[Acorn Archimedes]], and [[IBM PC compatible]]s.<ref name="Manning3" />{{rp|325–7|date=November 2012}} The 1985 [[Atari ST]] shipped with MIDI ports as part of the base system.

In 2015, Retro Innovations released the first MIDI interface for a [[VIC-20]], making the computer's four voices available to electronic musicians and retro-computing enthusiasts for the first time.<ref>{{cite web|title=VIC-20 MIDI Cartridge|url=http://store.go4retro.com/vic-20-midi-cartridge/|access-date=2021-02-28|website=RETRO Innovations|language=en|archive-date=21 January 2021|archive-url=https://web.archive.org/web/20210121182238/http://store.go4retro.com/vic-20-midi-cartridge/|url-status=live}}</ref> Retro Innovations also makes a MIDI interface cartridge  for [[Tandy Color Computer]] and [[Dragon 32/64|Dragon]] computers.<ref>{{cite web|title=MIDI Maestro – RETRO Innovations|url=http://www.go4retro.com/products/midi-maestro/|access-date=2021-02-28|language=en-US|archive-date=1 March 2021|archive-url=https://web.archive.org/web/20210301095814/https://www.go4retro.com/products/midi-maestro/|url-status=live}}</ref>

Chiptune musicians also use retro gaming consoles to compose, produce and perform music using MIDI interfaces. Custom interfaces are available for the Nintendo Entertainment System (NES)/Famicom,<ref>{{cite web|title=Famimimidi Famicom Version|url=https://catskullelectronics.com/products/famimimidi-famicom-version|access-date=2021-02-28|website=Catskull Electronics|language=en|archive-date=18 January 2021|archive-url=https://web.archive.org/web/20210118110512/https://catskullelectronics.com/products/famimimidi-famicom-version|url-status=dead}}</ref> Game Boy,<ref>{{cite web|title=Teensyboy Pro|url=https://catskullelectronics.com/products/teensyboy-pro|access-date=2021-02-28|website=Catskull Electronics|language=en|archive-date=18 January 2021|archive-url=https://web.archive.org/web/20210118103255/https://catskullelectronics.com/products/teensyboy-pro|url-status=dead}}</ref> Game Boy Advance<ref>{{cite web|title=GBA MIDI Synth|url=https://catskullelectronics.com/products/gba-midi-synth|access-date=2021-02-28|website=Catskull Electronics|language=en|archive-date=1 March 2021|archive-url=https://web.archive.org/web/20210301032949/https://catskullelectronics.com/products/gba-midi-synth|url-status=dead}}</ref> and Sega Genesis (Mega Drive).<ref>{{cite web|title=genMDM|url=https://catskullelectronics.com/products/genmdm|access-date=2021-02-28|website=Catskull Electronics|language=en|archive-date=25 February 2021|archive-url=https://web.archive.org/web/20210225083421/https://catskullelectronics.com/products/genmdm|url-status=dead}}</ref>

====Computer files====
[[File:Bach- Crab Canon from the Musical Offering.webm|thumb|MIDI files contain sound events such as a finger striking a key, which can be visualized using  software such as [[Synthesia (video game)|Synthesia]].]]

A MIDI file is not an audio recording. Rather, it is a set of instructions{{snd}}for example, for pitch or tempo{{snd}}and can use a thousand times less disk space than the equivalent recorded audio.<ref name="Crawford">Crawford, Walt. "MIDI and Wave: Coping with the Language". ''Online''. Vol. 20, No. 1. Jan/Feb 1996</ref><ref>{{citation |last=Aboukhadijeh |first=Feross. |url=https://feross.org/bitmidi/ |title=Announcing BitMidi |date=Aug 2018 |access-date=18 November 2018 |archive-date=4 October 2018 |archive-url=https://web.archive.org/web/20181004230746/https://feross.org/bitmidi/ |url-status=live }}</ref> Due to their tiny filesize, fan-made MIDI arrangements became an attractive way to share music online, before the advent of [[broadband internet access]] and multi-gigabyte hard drives.<ref>{{cite web |url=https://www.vice.com/en/article/the-internets-first-hit-file-format-wasnt-the-mp3-it-was-midi/ |title=The Internet's First Hit File Format Wasn't the MP3. It Was MIDI |date=8 November 2019 |access-date=2020-10-12 |archive-date=4 December 2020 |archive-url=https://web.archive.org/web/20201204091322/https://www.vice.com/en/article/a359xe/the-internets-first-hit-file-format-wasnt-the-mp3-it-was-midi |url-status=live }}</ref> The major drawback to this is the wide variation in quality of users' audio cards, and in the actual audio contained as samples or synthesized sound in the card that the MIDI data only refers to symbolically. Even a sound card that contains high-quality sampled sounds can have inconsistent quality from one sampled instrument to another.<ref name="Crawford" /> Early budget-priced cards, such as the [[AdLib]] and the [[Sound Blaster]] and its compatibles, used a stripped-down version of Yamaha's [[frequency modulation synthesis]] (FM synthesis) technology<ref name="WiffenFM">Wiffen, Paul. "[http://www.soundonsound.com/sos/1997_articles/sep97/synthschool3.html Synth School, Part 3: Digital Synthesis (FM, PD & VPM)] {{webarchive|url=https://web.archive.org/web/20051201090629/http://www.soundonsound.com/sos/1997_articles/sep97/synthschool3.html |date=1 December 2005 }}". ''Sound on Sound'' Sep 1997. Print.</ref> played back through low-quality digital-to-analog converters. The low-fidelity reproduction<ref name="Crawford" /> of these ubiquitous<ref name="WiffenFM" /> cards was often assumed to somehow be a property of MIDI itself. This created a perception of MIDI as low-quality audio, while in reality MIDI itself contains no sound,<ref name="Battino">Battino, David. ''[http://blogs.oreilly.com/digitalmedia/2005/10/finally-midi-20.html Finally: MIDI 2.0] {{webarchive|url=https://web.archive.org/web/20120816000340/http://blogs.oreilly.com/digitalmedia/2005/10/finally-midi-20.html|date=16 August 2012}}'' O'Reilly Digital Media Blog. O'Reilly Media, Inc. 6 October 2005. Web. 22 August 2012</ref> and the quality of its playback depends entirely on the quality of the sound-producing device.<ref name="Brewster" />{{rp|227|date=November 2012}}

{{Infobox file format
| name                   = Standard MIDI File
| extensions             = {{code|.mid}} {{code|.midi}} {{code|.smf}}  (Standard MIDI File) {{code|.rmi}}  (RIFF MIDI)
| mime                   = {{code|audio/midi}} {{code|audio/x-midi}}
| type_code              = Midi
| uniform type           = public.midi-audio{{cite web |url=https://developer.apple.com/documentation/uniformtypeidentifiers/uttype/3551530-midi |title=midi |work=Apple Developer Documentation: Uniform Type Identifiers |publisher=Apple Inc |access-date=22 May 2023 |archive-date=22 May 2023 |archive-url=https://web.archive.org/web/20230522155319/https://developer.apple.com/documentation/uniformtypeidentifiers/uttype/3551530-midi |url-status=live }}
| conforms_to            = public.audio
| magic                  = {{code|4D 54 68 64}} ("MThd" in ASCII; appears at the start of a MIDI file)
| max_size               = No strict limit; practical limits depend on hardware/software handling the file.
| owner                  = MIDI Manufacturers Association (MMA), International MIDI Association (IMA)
| type                   = Musical performance data (not actual audio)
| compression            = Uncompressed (but can be embedded in compressed archives)
| released               = 1990
| genre                  = Musical notation
| latest_release_version = MIDI 2.0
| latest_release_date    = 2020
| container_for          = MIDI data (notes, controllers, tempo, instrument changes)
| contained_by           = RIFF, Standard MIDI File
| extended_from          = Original MIDI 1.0 protocol
| extended_to            = MIDI 2.0 (adds higher resolution and two-way communication)
| standard               = MIDI Manufacturers Association (MMA) specifications
| open                   = Yes
| standards              = MIDI 1.0, MIDI 2.0 (since 2020)
| free                   = Yes
| url                    = [https://midi.org/standard-midi-files-specification https://midi.org/standard-midi-files-specification]
}}

The '''Standard MIDI File''' ('''SMF''') is a [[file format]] that provides a standardized way for music sequences to be saved, transported, and opened in other systems. The standard was developed and is maintained by the MMA, and usually uses a <code>.mid</code> extension.<ref>{{cite web|url=https://www.midi.org/specifications-old/item/standard-midi-files-smf|title=Standard MIDI Files (SMF) Specification|website=www.midi.org|access-date=23 October 2019|archive-date=23 October 2019|archive-url=https://web.archive.org/web/20191023033822/https://www.midi.org/specifications-old/item/standard-midi-files-smf|url-status=dead}}</ref> The compact size of these files led to their widespread use in computers, mobile phone [[ringtone]]s, webpage authoring and musical greeting cards. These files are intended for universal use and include such information as note values, timing and track names. Lyrics may be included as [[metadata]], and can be displayed by [[karaoke]] machines.<ref>Hass, Jeffrey. "[http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI10.shtml Chapter Three: How MIDI works 10] {{webarchive|url=https://web.archive.org/web/20150607074023/http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI10.shtml |date=7 June 2015 }}". Indiana University Jacobs School of Music. 2010. Web 13 August 2012</ref>

SMFs are created as an export format of software sequencers or hardware workstations. They organize MIDI messages into one or more parallel [[Multitrack recording|tracks]] and time-stamp the events so that they can be played back in sequence. A [[Header (computing)|header]] contains the arrangement's track count, tempo and an indicator of which of three SMF formats the file uses. A type 0 file contains the entire performance, merged onto a single track, while type 1 files may contain any number of tracks that are performed synchronously. Type 2 files are rarely used<ref>{{cite web |url=http://www.midi.org/aboutmidi/tut_midifiles.php |title=MIDI Files |archive-url=https://web.archive.org/web/20120822132443/http://www.midi.org/aboutmidi/tut_midifiles.php |archive-date=22 August 2012 |website=midi.org |publisher=Music Manufacturers Association |quote=a Type 2 was also specified originally but never really caught on}}</ref> and store multiple arrangements, with each arrangement having its own track and intended to be played in sequence.

=====RMID files=====
[[Microsoft Windows]] bundles SMFs together with [[Downloadable Sounds]] (DLS) in a [[Resource Interchange File Format]] (RIFF) wrapper, as '''RMID files''' with a <code>.rmi</code> extension. RIFF-RMID has been [[deprecated]] in favor of '''Extensible Music Files''' ([[XMF]]).<ref>"[http://www.digitalpreservation.gov/formats/fdd/fdd000120.shtml RIFF-based MIDI File Format] {{webarchive|url=https://web.archive.org/web/20120817183246/http://www.digitalpreservation.gov/formats/fdd/fdd000120.shtml |date=17 August 2012 }}". ''digitalpreservation.gov''. Library of Congress. 26 March 2012. Web. 18 August 2012</ref>

=====Software=====
{{Main|Comparison of MIDI editors and sequencers}}

The main advantage of the personal computer in a MIDI system is that it can serve a number of different purposes, depending on the software that is loaded.<ref name="Huber 1991" />{{rp|55|date=November 2012}} [[Computer multitasking|Multitasking]] allows simultaneous operation of programs that may be able to share data with each other.<ref name="Huber 1991" />{{rp|65|date=November 2012}}

=====Sequencers=====
{{Main|Music sequencer}}
{{See also|Audio sequencer|Digital audio workstation}}

Sequencing software can be used to manipulate recorded MIDI data with standard computer editing features such as [[cut, copy and paste]] and [[drag and drop]]. [[Keyboard shortcut]]s can be used to streamline workflow, and, in some systems, editing functions may be invoked by MIDI events. The sequencer can set each channel to play a different sound and gives a graphical overview of the arrangement. A variety of editing tools are made available, including a notation display or [[scorewriter]] that can be used to create printed parts for musicians. Tools such as [[Loop (music)|looping]], [[quantization (music)|quantization]], randomization, and [[transposition (music)|transposition]] simplify the arranging process.

[[Beat (music)|Beat]] creation is simplified, and [[groove (music)|groove]] templates can be used to duplicate another track's rhythmic feel. Realistic expression can be added through the manipulation of real-time controllers. Mixing can be performed, and MIDI can be synchronized with recorded audio and video tracks. Work can be saved, and transported between different computers or studios.<ref>Gellerman, Elizabeth. "Audio Editing SW Is Music to Multimedia Developers' Ears". ''Technical Horizons in Education Journal''. Vol. 22, No. 2. Sep 1994</ref><ref name="Desmond">Desmond, Peter. "ICT in the Secondary Music Curriculum". ''Aspects of Teaching Secondary Music: Perspectives on Practice''. ed. Gary Spruce. New York: RoutledgeFalmer, 2002</ref>{{rp|164–6|date=November 2012}}

Sequencers may take alternate forms, such as drum pattern editors that users can use to create beats by clicking on pattern grids,<ref name="Huber 1991" />{{rp|118|date=November 2012}} and loop sequencers such as [[ACID Pro]], which combine MIDI with prerecorded audio loops whose tempos and keys are matched to each other. Cue-list sequencing is used to trigger dialogue, sound effect, and music cues in stage and broadcast production.<ref name="Huber 1991" />{{rp|121|date=November 2012}}

=====Notation software=====
{{Main|Scorewriter}}
With MIDI, notes played on a keyboard can automatically be transcribed to [[sheet music]].<ref name="Holmes3" />{{rp|213|date=November 2012}} [[Scorewriter|Scorewriting]] software typically lacks advanced sequencing tools and is optimized for the creation of a neat, professional printout designed for live instrumentalists.<ref name="Desmond" />{{rp|157|date=November 2012}} These programs provide support for dynamics and expression markings, chord and lyric display, and complex score styles.<ref name="Desmond" />{{rp|167|date=November 2012}} Software is available that can print scores in [[braille]].<ref>Solomon, Karen. "[https://www.wired.com/culture/lifestyle/news/2000/02/34495 You Gotta Feel the Music] {{webarchive|url=https://web.archive.org/web/20090816175359/http://www.wired.com/culture/lifestyle/news/2000/02/34495 |date=16 August 2009 }}". ''wired.com''. Condé Nast. 27 February 2000. Web. 13 August 2012.</ref>

Notation programs include [[Finale (software)|Finale]], [[Encore (software)|Encore]], [[Sibelius (software)|Sibelius]], [[MuseScore]] and [[Dorico]]. [[SmartScore]] software can produce MIDI files from [[Image scanner|scanned]] sheet music.<ref>Cook, Janet Harniman. "[http://www.soundonsound.com/sos/dec98/articles/midiscan.265.htm Musitek Midiscan v2.51] {{webarchive|url=https://web.archive.org/web/20120110074408/http://www.soundonsound.com/sos/dec98/articles/midiscan.265.htm |date=10 January 2012 }}". ''Sound on Sound''. SOS Publications. Dec 1998. Print.</ref>

=====Editors and librarians=====
Users can program their equipment through the path editor as a computer interface. These became essential with the appearance of complex synthesizers such as the [[Yamaha FS1R]],<ref>{{cite magazine |last=Johnson |first=Derek |url=http://www.soundonsound.com/sos/mar99/articles/yamahafs1r.htm |title=Yamaha FS1R Editor Software |archive-url=https://web.archive.org/web/20111225133744/http://www.soundonsound.com/sos/mar99/articles/yamahafs1r.htm |archive-date=25 December 2011 |magazine=Sound on Sound |date=March 1999}}</ref> which contained several thousand programmable parameters, but had an interface that consisted of fifteen tiny buttons, four knobs and a small LCD.<ref>{{cite magazine |last1=Johnson |first1=Derek |first2=Debbie |last2=Poyser |url=http://www.soundonsound.com/sos/dec98/articles/yamfs1r.549.htm |title=Yamaha FS1R |archive-url=https://web.archive.org/web/20070415184804/http://www.soundonsound.com/sos/dec98/articles/yamfs1r.549.htm |archive-date=15 April 2007 |magazine=Sound on Sound |date=December 1998}}</ref> Digital instruments typically discourage users from experimentation, due to their lack of the feedback and direct control that switches and knobs would provide,<ref name="Gibbs" />{{rp|393|date=November 2012}} but patch editors give owners of hardware instruments and effects devices the same editing functionality that is available to users of software synthesizers.<ref>{{cite web |url=http://www.squest.com/Products/MidiQuest11/index.html |title=Sound Quest MIDI Quest 11 Universal Editor |archive-url=https://web.archive.org/web/20140306223334/http://www.squest.com/Products/MidiQuest11/index.html |archive-date=6 March 2014 |website=squest.com}}</ref> Some editors are designed for a specific instrument or effects device, while other, ''universal'' editors support a variety of equipment, and ideally can control the parameters of every device in a setup through the use of System Exclusive messages.<ref name="Huber 1991"/>{{rp|129|date=November 2012}} System Exclusive messages use the MIDI protocol to send information about the synthesizer's parameters.

Patch librarians have the specialized function of organizing the sounds in a collection of equipment and exchanging entire banks of sounds between an instrument and a computer. In this way the device's limited patch storage is augmented by a computer's much greater disk capacity.<ref name="Huber 1991"/>{{rp|133|date=November 2012}} Once transferred to the computer, custom patches can be shared with other owners of the same instrument.<ref name="Cakewalk">{{cite web |url=http://www.cakewalk.com/support/kb/reader.aspx/2007013074 |title=Desktop Music Handbook&nbsp;– MIDI |archive-url=https://web.archive.org/web/20120814222211/http://www.cakewalk.com/Support/kb/reader.aspx/2007013074 |archive-date=14 August 2012 |website=cakewalk.com |publisher=Cakewalk, Inc. |date=26 November 2010}}</ref> Universal editor/librarians that combine the two functions were once common, and included Opcode Systems' Galaxy, [[Emagic|eMagic]]'s SoundDiver, and MOTU's Unisyn. Although these older programs have been largely abandoned with the trend toward computer-based synthesis using virtual instruments, several editor/librarians remain available, including Coffeeshopped Patch Base,<ref>{{cite web | url=https://coffeeshopped.com/patch-base | title=Patch Base | access-date=7 September 2022 | archive-date=7 September 2022 | archive-url=https://web.archive.org/web/20220907055311/https://coffeeshopped.com/patch-base | url-status=live }}</ref> Sound Quest's Midi Quest, and several editors from Sound Tower. [[Native Instruments]]' Kore was an effort to bring the editor/librarian concept into the age of software instruments,<ref>{{cite web |first=Simon |last=Price |url=http://www.soundonsound.com/sos/jul06/articles/nikore.htm |title=Native Instruments Kore |publisher=Sound on Sound |date=July 2006 |website=Soundonsound.com |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20130602131027/http://www.soundonsound.com/sos/jul06/articles/nikore.htm |archive-date=2 June 2013}}</ref> but was abandoned in 2011.<ref>{{Cite web|url=https://www.musicradar.com/news/tech/native-instruments-discontinues-kore-457945|title=Native Instruments discontinues Kore|author1=Ben Rogerson|date=7 June 2011|website=MusicRadar|access-date=7 September 2022|archive-date=7 September 2022|archive-url=https://web.archive.org/web/20220907055313/https://www.musicradar.com/news/tech/native-instruments-discontinues-kore-457945|url-status=live}}</ref>

=====Auto-accompaniment programs=====
Programs that can dynamically generate accompaniment tracks are called ''auto-accompaniment'' programs. These create a full-band arrangement in a style that the user selects and sends the result to a MIDI sound-generating device for playback. The generated tracks can be used as educational or practice tools, as accompaniment for live performances, or as a songwriting aid.<ref name="Bozeman" />{{rp|42|date=November 2012}}

=====Synthesis and sampling=====
{{Main|Software synthesizer|Software sampler}}
Computers can use software to generate sounds, which are then passed through a [[digital-to-analog converter]] (DAC) to a power amplifier and loudspeaker system.<ref name="Holmes3" />{{rp|213|date=November 2012}} The number of sounds that can be played simultaneously (the [[polyphony]]) is dependent on the power of the computer's [[CPU]], as are the [[sample rate]] and [[Audio bit depth|bit depth]] of playback, which directly affect the quality of the sound.<ref>{{cite magazine |last=Lehrman |first=Paul D. |url=http://www.soundonsound.com/sos/1995_articles/oct95/softwaresynthesis.html |title=Software Synthesis: The Wave Of The Future? |archive-url=https://web.archive.org/web/20120110172147/http://www.soundonsound.com/sos/1995_articles/oct95/softwaresynthesis.html |archive-date=10 January 2012  |magazine=Sound on Sound |publisher=SOS Publications |date=October 1995}}</ref> Synthesizers implemented in software are subject to timing issues that are not necessarily present with hardware instruments, whose dedicated operating systems are not subject to interruption from background tasks as desktop [[operating system]]s are. These timing issues can cause synchronization problems, and clicks and pops when sample playback is interrupted. Software synthesizers also may exhibit additional [[latency (audio)|latency]] in their sound generation.<ref name="WalkerTime">{{cite magazine |last=Walker |first=Martin |url=https://www.soundonsound.com/techniques/identifying-solving-pc-midi-audio-timing-problems |title=Identifying & Solving PC MIDI & Audio Timing Problems |archive-url=https://web.archive.org/web/20120110151234/http://www.soundonsound.com/sos/mar01/articles/pcmusician.asp |archive-date=10 January 2012 |magazine=Sound on Sound |publisher=SOS Publications |date=March 2001 |url-status=live}}</ref>

The roots of software synthesis go back as far as the 1950s, when [[Max Mathews]] of [[Bell Labs]] wrote the [[MUSIC-N]] programming language, which was capable of non-real-time sound generation.<ref name="DMM1997">{{cite magazine |last=Miller |first=Dennis |url=http://www.soundonsound.com/sos/1997_articles/may97/softwaresynth2.html |title=Sound Synthesis On A Computer, Part 2 |archive-url=https://web.archive.org/web/20120110201713/http://www.soundonsound.com/sos/1997_articles/may97/softwaresynth2.html |archive-date=10 January 2012 |magazine=Sound on Sound |publisher=SOS Publications |date=May 1997}}</ref> Reality, by Dave Smith's [[Seer Systems]] was an early synthesizer that ran directly on a host computer's CPU. Reality achieved a low latency through tight driver integration, and therefore could run only on [[Creative Labs]] soundcards.<ref>{{cite web |url=http://www.keyboardmag.com/article/Midi-Ancestors-and-Milestones/2171 |title=MIDI Ancestors and Milestones |archive-url=https://web.archive.org/web/20121030112748/http://www.keyboardmag.com/article/Midi-Ancestors-and-Milestones/2171 |archive-date=30 October 2012 |publisher=[[New Bay Media]]}}</ref><ref>{{cite magazine |last=Walker |first=Martin |url=http://www.soundonsound.com/sos/1997_articles/nov97/seerreality.html |title=Reality PC |archive-url=https://web.archive.org/web/20150225043325/http://www.soundonsound.com/sos/1997_articles/nov97/seerreality.html |archive-date=25 February 2015 |magazine=Sound on Sound |publisher=SOS Publications |date=November 1997}}</ref> Syntauri Corporation's Alpha Syntauri was another early software-based synthesizer. It ran on the Apple IIe computer and used a combination of software and the computer's hardware to produce additive synthesis.<ref>{{cite web | url=https://www.vintagesynth.com/misc/alphasyntauri.php | title=Syntauri alphaSyntauri &#124; Vintage Synth Explorer | access-date=7 September 2022 | archive-date=7 September 2022 | archive-url=https://web.archive.org/web/20220907060813/https://www.vintagesynth.com/misc/alphasyntauri.php | url-status=live }}</ref> Some systems use dedicated hardware to reduce the load on the host CPU, as with [[Symbolic Sound Corporation]]'s Kyma System,<ref name="DMM1997" /> and the [[Creamware (company)|Creamware]]/[[Sonic Core]] Pulsar/SCOPE systems,<ref>{{cite magazine |last=Wherry |first=Mark |url=http://www.soundonsound.com/sos/jun03/articles/creamwarescope.asp |title=Creamware SCOPE |archive-url=https://web.archive.org/web/20111225043650/http://www.soundonsound.com/sos/jun03/articles/creamwarescope.asp |archive-date=25 December 2011 |magazine=Sound on Sound |publisher=SOS Publications |date=June 2003}}</ref> which power an entire recording studio's worth of instruments, [[effect unit]]s, and [[audio console|mixer]]s.<ref>{{cite web |last=Anderton |first=Craig |url=http://www.keyboardmag.com/article/sonic-core-scope-xite-1/147874 |title=Sonic Core SCOPE Xite-1 |archive-url=https://web.archive.org/web/20121030112726/http://www.keyboardmag.com/article/sonic-core-scope-xite-1/147874 |archive-date=30 October 2012 |publisher=[[New Bay Media]]}}</ref> The ability to construct full MIDI arrangements entirely in computer software allows a composer to render a finalized result directly as an audio file.<ref name="Why" />

=====Game music=====
Early PC games were distributed on floppy disks, and the small size of MIDI files made them a viable means of providing soundtracks. Games of the [[DOS]] and early Windows eras typically required compatibility with either [[Ad Lib, Inc.|Ad Lib]] or [[Sound Blaster]] audio cards. These cards used [[FM synthesis]], which generates sound through [[modulation]] of [[sine wave]]s. [[John Chowning]], the technique's pioneer, theorized that the technology would be capable of accurate recreation of any sound if [[Additive synthesis|enough sine waves were used]], but budget computer audio cards performed FM synthesis with only two sine waves. Combined with the cards' 8-bit audio, this resulted in a sound described as "artificial"<ref>David Nicholson. "[http://www.highbeam.com/doc/1P2-946733.html HARDWARE]."{{webarchive|url=https://web.archive.org/web/20130502120852/http://www.highbeam.com/doc/1P2-946733.html |date=2 May 2013 }} The Washington Post. 1993.</ref> and "primitive".<ref name="Levy">Levy, David S. "[http://www.highbeam.com/doc/1G1-14803399.html Aztech's WavePower daughtercard improves FM reception. (Aztech Labs Inc.'s wavetable synthesis add-on card for Sound Blaster 16 or Sound Galaxy Pro 16 sound cards) (Hardware Review) (Evaluation).] {{webarchive|url=https://web.archive.org/web/20130502121538/http://www.highbeam.com/doc/1G1-14803399.html |date=2 May 2013 }}" Computer Shopper. SX2 Media Labs LLC. 1994.</ref>

Wavetable [[daughterboard]]s that were later available provided audio samples that could be used in place of the FM sound. These were expensive, but often used the sounds from respected MIDI instruments such as the [[E-mu Proteus]].<ref name="Levy" /> The computer industry moved in the mid-1990s toward wavetable-based soundcards with 16-bit playback but standardized on a 2&nbsp;MB of wavetable storage, a space too small in which to fit good-quality samples of 128 General MIDI instruments plus drum kits. To make the most of the limited space, some manufacturers stored 12-bit samples and expanded those to 16 bits on playback.<ref>Labriola, Don. "[http://www.highbeam.com/doc/1G1-16232686.html MIDI masters: wavetable synthesis brings sonic realism to inexpensive sound cards. (review of eight Musical Instrument Digital Interface sound cards) (includes related articles about testing methodology, pitfalls of wavetable technology, future wavetable developments) (Hardware Review) (Evaluation).]"{{webarchive|url=https://web.archive.org/web/20130502104559/http://www.highbeam.com/doc/1G1-16232686.html |date=2 May 2013 }} Computer Shopper. SX2 Media Labs LLC. 1994.</ref>

===Other applications===
Despite its association with music devices, MIDI can control any electronic or digital device that can read and process a MIDI command. MIDI has been adopted as a control protocol in a number of non-musical applications. [[MIDI Show Control]] uses MIDI commands to direct stage lighting systems and to trigger cued events in theatrical productions. [[VJ (video performance artist)|VJ]]s and [[Turntablism|turntablists]] use it to cue clips, and to synchronize equipment, and recording systems use it for synchronization and [[Console automation|automation]].  Wayne Lytle, the founder of [[Animusic]], derived a system he dubbed MIDIMotion in order to produce the ''Animusic'' series of computer-animated music video albums; Animusic would later design its own animation software specifically for MIDIMotion called Animotion.<ref>{{Cite web |title=Animusic-MIDI-Driven Computer Animation – MIDI.org |url=https://midi.org/animusic-midi-driven-computer-animation |access-date=2024-10-19 |website=midi.org}}</ref>  [[Apple Motion]] allows for a similar control of animation parameters through MIDI. The 1987 [[first-person shooter]] game ''[[MIDI Maze]]'' and the 1990 [[Atari ST]] [[computer puzzle game]] ''[[Oxyd]]'' used MIDI to network computers together.

==Devices==
{{Multi image
| image1            = Midi ports and cable.jpg
| caption1          = 5-pin DIN MIDI cable plugged in a socket
| image2            = MIDI connector2.svg
| caption2          = DIN connector pin numbers
| total_width       = 210
}}

===Connectors and interface===

==== DIN connector ====
Per the original MIDI 1.0 standard, cables terminate in a [[DIN connector|180° five-pin DIN connector]] (DIN 41524). Typical applications use only three of the five conductors: a [[ground (electricity)|ground]] wire (pin 2), and a [[balanced pair]] of conductors (pins 4 and 5) that carry the MIDI signal as an [[electric current]].<ref>{{cite web|title=5 Pin DIN Electrical Specs|url=https://www.midi.org/specifications/midi-transports-specifications/5-pin-din-electrical-specs|access-date=2021-04-08|website=The MIDI Association|language=en-gb|archive-date=28 May 2021|archive-url=https://web.archive.org/web/20210528115750/https://www.midi.org/specifications/midi-transports-specifications/5-pin-din-electrical-specs|url-status=dead}}</ref><ref name="Bozeman">Bozeman, William C. ''Educational Technology: Best Practices from America's Schools''. Larchmont: Eye on Education, 1999.</ref>{{rp|41|date=November 2012}} This connector configuration can only carry messages in one direction, so a second cable is necessary for two-way communication.<ref name="Huber 1991">{{cite book |last=Huber |first=David Miles |title=The MIDI Manual |location=Carmel, Indiana |publisher=SAMS |date=1991 |isbn=978-0-672-22757-8 |url=https://archive.org/details/midimanual00hube }}</ref>{{rp|13|date=November 2012}} Some proprietary applications, such as [[Phantom power|phantom-powered]] footswitch controllers, use the spare pins for [[direct current]] (DC) power transmission.<ref>Lockwood, Dave. "[http://www.soundonsound.com/sos/dec01/articles/tcgmajor.asp TC Electronic G Major] {{webarchive|url=https://web.archive.org/web/20120320113908/http://www.soundonsound.com/sos/dec01/articles/tcgmajor.asp |date=20 March 2012 }}". ''Sound on Sound''. SOS Publications. Dec 2001. Print.</ref>

[[Opto-isolator]]s keep MIDI devices electrically separated from their MIDI connections, which prevents [[Ground loop (electricity)|ground loops]]<ref>Mornington-West, Allen. "Digital Theory". ''Sound Recording Practice''. 4th Ed. Ed. John Borwick. Oxford: Oxford University Press, 1996.</ref>{{rp|63|date=November 2012}} and protects equipment from voltage spikes.<ref name="Manning3" />{{rp|277|date=November 2012}} There is no [[error detection]] capability in MIDI, so the maximum cable length is set at {{convert|15|meters|feet}} to limit [[interference (communication)|interference]].<ref>"[http://www.richmondsounddesign.com/faq.html#midilen Richmond Sound Design&nbsp;– Frequently Asked Questions] {{webarchive|url=https://web.archive.org/web/20060105205625/http://www.richmondsounddesign.com/faq.html |date=5 January 2006 }}". ''richmondsounddesign.com''. Web. 5 August 2012.</ref>

==== TRS minijack connector ====
To save space, some MIDI devices (smaller ones in particular) started using 3.5&nbsp;mm [[Phone connector (audio)|TRS phone connectors]] (also known as audio minijack connectors).<ref>{{cite web |last=Kirn |first=Peter |date=2015-08-26 |title=What if we used stereo minijack cables for MIDI? |url=https://cdm.link/2015/08/used-stereo-minijack-cables-midi/ |url-status=live |archive-url=https://web.archive.org/web/20230419015513/https://cdm.link/2015/08/used-stereo-minijack-cables-midi/ |archive-date=2023-04-19}}</ref> This became widespread enough that the MIDI Manufacturers' Association standardized the wiring.<ref>{{cite web |title=Specification for TRS Adapters Adopted and Released |url=https://www.midi.org/midi-articles/trs-specification-adopted-and-released |website=www.midi.org |access-date=30 August 2023 |archive-date=30 August 2023 |archive-url=https://web.archive.org/web/20230830172520/https://www.midi.org/midi-articles/trs-specification-adopted-and-released |url-status=dead }}</ref> The MIDI-over-minijack standards document also recommends the use of 2.5&nbsp;mm connectors over 3.5&nbsp;mm ones to avoid confusion with audio connectors.<ref>{{cite web |date=21 August 2018 |title=It's official: minijack connections are now kosher for MIDI |url=https://cdm.link/2018/08/midi-minijack-trs/ |access-date=24 July 2019 |archive-date=24 July 2019 |archive-url=https://web.archive.org/web/20190724033640/https://cdm.link/2018/08/midi-minijack-trs/ |url-status=live }}</ref>

=== Thru port ===
Most devices do not copy messages from their input to their output port. A third type of port, the ''thru'' port, emits a copy of everything received at the input port, allowing data to be forwarded to another instrument<ref name="Manning3" />{{rp|278|date=November 2012}} in a [[Daisy chain (electrical engineering)|daisy-chain]] arrangement.<ref name="indiana.edu">Hass, Jeffrey. "[http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI2.shtml Chapter Three: How MIDI works 2] {{webarchive|url=https://web.archive.org/web/20150617205248/http://www.indiana.edu/~emusic/etext/MIDI/chapter3_MIDI2.shtml |date=17 June 2015 }}". Indiana University Jacobs School of Music. 2010. Web. 13 August 2012.</ref> Not all devices feature thru ports, and devices that lack the ability to generate MIDI data, such as effects units and sound modules, may not include out ports.<ref name="Gibbs">Gibbs, Jonathan (Rev. by Peter Howell) "Electronic Music". ''Sound Recording Practice'', 4th Ed. Ed. John Borwick. Oxford: Oxford University Press, 1996</ref>{{rp|384|date=November 2012}}

===Management devices===
Each device in a daisy chain adds delay to the system. This can be avoided by using a MIDI thru box, which contains several outputs that provide an exact copy of the box's input signal. A MIDI merger is able to combine the input from multiple devices into a single stream, and allows multiple controllers to be connected to a single device. A MIDI switcher allows switching between multiple devices, and eliminates the need to physically repatch cables. MIDI routers combine all of these functions. They contain multiple inputs and outputs, and allow any combination of input channels to be routed to any combination of output channels. Routing setups can be created using computer software, stored in memory, and selected by MIDI program change commands.<ref name="Huber 1991" />{{rp|47–50|date=November 2012}} This enables the devices to function as standalone MIDI routers in situations where no computer is present.<ref name="Huber 1991"/>{{rp|62–3|date=November 2012}}<ref>{{cite web |url=https://www.geeky-gadgets.com/midi-router-control-center-10-09-2019/ |title=MIDI Router Control Center a modern reinvention of the MIDI router |date=September 10, 2019 |author=Julian Horsey |access-date=10 May 2022 |archive-date=2 October 2022 |archive-url=https://web.archive.org/web/20221002152313/https://www.geeky-gadgets.com/midi-router-control-center-10-09-2019/ |url-status=live }}</ref> MIDI data processors are used for utility tasks and special effects. These include MIDI filters, which remove unwanted MIDI data from the stream, and MIDI delays, effects that send a repeated copy of the input data at a set time.<ref name="Huber 1991" />{{rp|51|date=November 2012}}

===Interfaces===
A computer MIDI interface's main function is to synchronize communications between the MIDI device and the computer.<ref name="indiana.edu"/> Some computer sound cards include a standard MIDI connector, whereas others connect by any of various means that include the [[D-subminiature]] DA-15 [[game port]], [[USB]], [[FireWire]], [[Ethernet]] or a proprietary connection. The increasing use of [[USB]] connectors in the 2000s has led to the availability of MIDI-to-USB data interfaces that can transfer MIDI channels to USB-equipped computers. Some MIDI keyboard controllers are equipped with USB jacks, and can be connected directly to computers that run music software.

MIDI's serial transmission leads to timing problems. A three-byte MIDI message requires nearly 1&nbsp;millisecond for transmission.<ref>Robinson, Herbie. "[http://lists.apple.com/archives/coreaudio-api/2005/Jul/msg00120.html Re: core midi time stamping] {{webarchive|url=https://web.archive.org/web/20121028045258/http://lists.apple.com/archives/coreaudio-api/2005/Jul/msg00120.html |date=28 October 2012 }}". ''Apple Coreaudio-api Mailing List''. Apple, Inc. 18 July 2005. 8 August 2012.</ref> Because MIDI is serial, it can only send one event at a time. If an event is sent on two channels at once, the event on the second channel cannot transmit until the first one is finished, and so is delayed by 1&nbsp;ms. If an event is sent on all channels at the same time, the last channel's transmission is delayed by as much as 16&nbsp;ms. This contributed to the rise of MIDI interfaces with multiple in- and out-ports, because timing improves when events are spread between multiple ports as opposed to multiple channels on the same port.<ref name="WalkerTime" /> The term ''MIDI slop'' refers to audible timing errors that result when MIDI transmission is delayed.<ref>Shirak, Rob. "[http://www.emusician.com/news/0766/mark-of-the-unicorn/140335 Mark of the Unicorn] {{webarchive|url=https://web.archive.org/web/20140323225235/http://www.emusician.com/news/0766/mark-of-the-unicorn/140335 |date=23 March 2014 }}". ''emusician.com''. New Bay Media. 1 October 2000. Web. Retrieved 8 August 2012.</ref>

===Controllers===
{{Main|MIDI controller}}
[[File:Remote 25.jpg|thumb|alt=A Novation Remote 25 two-octave MIDI controller|Smaller MIDI controllers are popular due to their portability. This two-[[octave]] unit provides a variety of controls for manipulating various sound design parameters of computer-based or standalone hardware instruments, effects, mixers and recording devices.]]
There are two types of MIDI controllers: performance controllers that generate notes and are used to perform music,<ref>"[http://www.rolandmusiced.com/spotlight/article.php?ArticleId=1040 MIDI Performance Instruments]". {{webarchive|url=https://web.archive.org/web/20121118195443/http://www.rolandmusiced.com/spotlight/article.php?ArticleId=1040 |date=18 November 2012 }}. ''Instruments of Change''. Vol. 3, No. 1 (Winter 1999). Roland Corporation, U.S.</ref> and controllers that may not send notes, but transmit other types of real-time events. Many devices are a combination of the two types.

[[MIDI keyboard|Keyboard]]s are by far the most common type of MIDI controller.<ref name="Cakewalk" /> MIDI was designed with keyboards in mind and any controller that is not a keyboard is considered an "alternative" controller.<ref>{{cite web |url=http://www.midi.org/aboutmidi/products.php |title=MIDI Products |archive-url=https://web.archive.org/web/20120716225141/http://www.midi.org/aboutmidi/products.php |archive-date=16 July 2012 |publisher=MIDI Manufacturers Association |date=1 August 1012}}</ref> This was seen as a limitation by composers who were not interested in keyboard-based music, but the standard proved flexible, and MIDI compatibility was introduced to other types of controllers, including guitars, and other stringed instruments and [[drum controller]]s and [[wind controller]]s, which emulate the playing of [[drum kit]] and wind instruments, respectively and specialized and experimental controllers.<ref name="Holmes3" />{{rp|23|date=November 2012}} Nevertheless, some features of the keyboard playing for which MIDI was designed do not fully capture other instruments' capabilities; [[Jaron Lanier]] cites the standard as an example of technological "lock-in" that unexpectedly limited what was possible to express.<ref name="You Are Not a Gadget">{{Cite book |title=You Are Not a Gadget |last=Lanier |first=Jaron |publisher=Vintage |year=2011 |isbn=978-0-307-38997-8 |location=New York |url-access=registration |url=https://archive.org/details/isbn_9780307269645 }}</ref> Some of these shortcomings have been addressed in [[#Extensions|extensions]] to the protocol.

Software synthesizers offer great power and versatility, but some players feel that division of attention between a MIDI keyboard and a computer keyboard and mouse robs some of the immediacy from the playing experience.<ref>Preve, Francis. "Dave Smith", in "The 1st Annual ''Keyboard'' Hall of Fame". ''Keyboard'' (US). NewBay Media, LLC. Sep 2012. Print. p.18</ref> Devices dedicated to real-time MIDI control provide an ergonomic benefit and can provide a greater sense of connection with the instrument than an interface that is accessed through a computer. Controllers may be general-purpose devices that are designed to work with a variety of equipment, or they may be designed to work with a specific piece of software. Examples of the latter include Akai's APC40 controller for [[Ableton Live]], and Korg's MS-20ic controller, a reproduction of the control panel on their [[MS-20]] analog synthesizer. The MS-20ic controller includes [[patch cables]] that can be used to control signal routing in their virtual reproduction of the MS-20 synthesizer and can also control third-party devices.<ref>"[http://www.vintagesynth.com/korg/legacy.php Korg Legacy Collection]". {{webarchive|url=https://web.archive.org/web/20120916101912/http://www.vintagesynth.com/korg/legacy.php |date=16 September 2012 }}. ''Vintage Synth Explorer''. Accessed 21 August 2012.</ref>

===Instruments===
[[File:Korg 05RW front.jpg|thumb|alt=A General MIDI sound module.|A [[sound module]], which requires an external controller (e.g., a MIDI keyboard) to trigger its sounds. These devices are highly portable, but their limited programming interface requires computer-based tools for comfortable access to their sound parameters.]]

A MIDI instrument contains ports to send and receive MIDI signals, a CPU to process those signals, an interface for user programming, audio circuitry to generate sound, and controllers. The operating system and factory sounds are often stored in a [[read-only memory]] (ROM) unit.<ref name="Huber 1991" />{{rp|67–70|date=November 2012}}

A MIDI instrument can also be a stand-alone module (without a piano-style keyboard) consisting of a General MIDI soundboard (GM, GS and XG), onboard editing, including transposing, MIDI instrument selection and adjusting volume, pan, reverb levels and other MIDI controllers. Typically, the MIDI module includes a screen, so the user can view information for the currently selected function.

====Synthesizers====
Synthesizers may employ any of a variety of sound generation techniques. They may include an integrated keyboard or may exist as sound modules that generate sounds when triggered by an external controller, such as a MIDI keyboard. Sound modules are typically designed to be mounted in a [[19-inch rack]].<ref name="Huber 1991" />{{rp|70–72|date=November 2012}} Manufacturers commonly produce a synthesizer in both standalone and rack-mounted versions, and often offer the keyboard version in a variety of sizes.

====Samplers====
A [[sampler (musical instrument)|sampler]] can record and digitize audio, store it in [[random-access memory]] (RAM), and play it back. With a sampler, users typically can edit a [[Sampling (signal processing)|sample]] and save it to a hard disk, apply effects to it, and shape it with the same tools that [[subtractive synthesizer]]s use. They also may be available in either keyboard or rack-mounted form.<ref name="Huber 1991" />{{rp|74–8|date=November 2012}} Instruments that generate sounds through sample playback, but have no recording capabilities, are known as "[[Rompler|ROMplers]]".

Samplers did not become established as viable MIDI instruments as quickly as synthesizers did due to the expense of memory and processing power at the time.<ref name="Manning3" />{{rp|295|date=November 2012}} The first low-cost MIDI sampler was the [[Ensoniq Mirage]], introduced in 1984.<ref name="Manning3" />{{rp|304|date=November 2012}} MIDI samplers are typically limited by displays that are too small to use to edit sampled waveforms, although some can be connected to a computer monitor.<ref name="Manning3" />{{rp|305|date=November 2012}}

====Drum machines====
[[Drum machine]]s typically are sample playback devices that specialize in drum and percussion sounds. They commonly contain a sequencer for creating drum patterns and arranging them into a song. There often are multiple audio outputs so that each sound or group of sounds can be routed to a separate output. The individual drum voices may be playable from another MIDI instrument or from a sequencer.<ref name="Huber 1991" />{{rp|84|date=November 2012}}

====Workstations and hardware sequencers====
{{Further|Music workstation|Music sequencer}}
[[File:Tenori-on.jpg|thumb|alt=A button matrix MIDI controller|Yamaha's [[Tenori-on]] controller allows arrangements to be built by "drawing" on its array of lighted buttons. The resulting arrangements can be played back using its internal sounds or external sound sources, or recorded in a computer-based sequencer.]]

Sequencer technology predates MIDI. [[Analog sequencer]]s use [[CV/Gate]] signals to control pre-MIDI analog synthesizers. MIDI sequencers typically are operated by transport features modeled after those of [[tape deck]]s. They are capable of recording MIDI performances and arranging them into individual tracks using a [[multitrack recording]] paradigm. Music workstations combine controller keyboards with an internal sound generator and a sequencer. These can be used to build complete arrangements and play them back using their own internal sounds and function as self-contained music production studios. They commonly include file storage and transfer capabilities.<ref name="Huber 1991" />{{rp|103–4|date=November 2012}}

===Effects units===
Some [[effects unit]]s can be remotely controlled via MIDI. For example, the [[Eventide, Inc|Eventide]] H3000 Ultra-harmonizer allows such extensive MIDI control that it is playable as a synthesizer.<ref name="Manning3" />{{rp|322|date=November 2012}} The [[Drum Buddy]], a pedal-format [[drum machine]], has a MIDI connection so that it can have its tempo synchronized with a [[looper pedal]] or time-based effects such as delay.

==Technical specifications==
[[File:8-N-1 MIDI two-bytes.png|thumb|342x342px|8-N-1 [[asynchronous serial communication]] of two MIDI bytes. Each 8-bit byte is preceded by a start bit and succeeded by a stop bit for [[Frame synchronization|framing]] purposes, to total 10 bits.<ref name="Manning3" />{{rp|286|date=November 2012}} So while the 31,250&nbsp;[[baud rate]] corresponds to 31.25&nbsp;[[kbit/s]], the [[net bit rate|''net'' bit rate]] is only 25&nbsp;kbit/s. Each byte with its frame uses 320&nbsp;[[microseconds]].<ref name="MIDI specification">{{cite web |last=MMA |title=MIDI DIN Electrical Specification |url=http://www.midi.org/techspecs/ca33.pdf |url-status=live |archive-url=https://web.archive.org/web/20151222120442/http://www.midi.org/techspecs/ca33.pdf |archive-date=22 December 2015 |access-date=31 August 2016}}</ref>]]

MIDI messages are made up of 8-bit [[bytes]] transmitted at 31,250{{efn|The 31,250&nbsp;[[baud rate]] is used because it is an exact division of 1&nbsp;MHz,<ref name="Manning3" />{{rp|286|date=November 2012}} a common divisor of the maximum [[clock rate]] of most [[Microprocessor chronology|early microprocessors]].}}&nbsp;(±1%)&nbsp;[[baud]] using 8-N-1 [[asynchronous serial communication]] as described in the figure. The first bit of each byte identifies whether the byte is a ''status'' byte or a ''data'' byte, and is followed by seven bits of information.<ref name="Huber 1991" />{{rp|13–14|date=November 2012}}

A MIDI link can carry sixteen independent channels, numbered 1–16. A device may listen to specific channels and ignore messages on other channels (''omni off'' mode), or it can listen to all channels, effectively ignoring the channel address (''omni on'').

A device that is [[polyphonic]] can sound multiple notes simultaneously, until the device's polyphony limit is reached, or the notes reach the end of their [[ADSR envelope#ADSR envelope|decay envelope]], or explicit ''note-off'' MIDI commands are received. A device that is [[monophonic]] instead terminates any previous note when new ''note-on'' commands arrive.

''Some'' receiving devices may be set to all four combinations of ''omni off/on'' and ''mono/poly'' modes.<ref name="Huber 1991" />{{rp|14–18|date=November 2012}}

===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.

===Electrical specifications===
MIDI 1.0's electrical interface is based around a fully isolated [[current loop]]<ref name="MIDI specification" /> along the red and blue lines in the following [[Circuit diagram|schematic]]:
[[File:MIDI IN OUT simplified schematic twisted-pair.svg|alt=MIDI interconnection schematic|center|718x718px]]
"DIN / TRS" in this schematic indicates that either a [[DIN connector]]{{Efn|The original MIDI 1.0 specification mandated DIN-5. The current source pin or hot pin ("H" in this schematic) corresponds to pin 4 of a 5-pin DIN. The current sink or cold pin ("C" in this schematic) corresponds to pin 5 of that DIN. The shield pin ("S" in this schematic) corresponds to pin 2 of that DIN.}} or a [[TRS phone connector]]{{Efn|Three variants on how to use TRS phone connectors are called ''Type A'', ''Type B'', and ''TS'' (a.k.a. ''Type C'' or ''Non-TRS''). ''Type A'' became part of the MIDI standard in 2018. ''Type A'' pin assignments are: the current source or hot pin ("H" in the schematic) is ring of the TRS, the current sink or cold pin ("C" in the schematic) is the tip of the TRS, and the shield ("S" in the schematic) is the sleeve of the TRS.}} may be used.<ref>{{Cite web |title=[Updated] How to Make Your Own 3.5mm mini stereo TRS-to-MIDI 5 pin DIN cables |url=https://www.midi.org/midi-articles/updated-how-to-make-your-own-3-5mm-mini-stereo-trs-to-midi-5-pin-din-cables |access-date=2023-12-14 |website=The MIDI Association |language=en-gb |archive-date=14 December 2023 |archive-url=https://web.archive.org/web/20231214070734/https://www.midi.org/midi-articles/updated-how-to-make-your-own-3-5mm-mini-stereo-trs-to-midi-5-pin-din-cables |url-status=live }}</ref><ref>{{Cite web |title=A simplified guide to MIDI over TRS minijacks – minimidi.world |url=https://minimidi.world/ |access-date=2023-12-14 |website=minimidi.world |archive-date=14 December 2023 |archive-url=https://web.archive.org/web/20231214070735/https://minimidi.world/ |url-status=live }}</ref>

To transmit a logic&nbsp;0 and a start bit, the sender's [[UART]]{{Efn|Universal Asynchronous Receiver/Transmitter ([[UART]]) is hardware that transports bytes between digital devices. When MIDI was new, most synthesizers used discrete, external UART chips, such as the [[8250]] or [[16550 UART]], but UARTs have since moved into [[microcontrollers]].<ref name=SparkFun>{{Cite web |title=MIDI Tutorial - SparkFun Learn |url=https://learn.sparkfun.com/tutorials/midi-tutorial/hardware--electronic-implementation |access-date=2023-12-15 |website=[[SparkFun]] |archive-date=15 December 2023 |archive-url=https://web.archive.org/web/20231215011929/https://learn.sparkfun.com/tutorials/midi-tutorial/hardware--electronic-implementation |url-status=live }}</ref>}} produces a low voltage. This results in a nominal 5&nbsp;[[milliampere]]s<ref name="MIDI specification" /> current flow [[Current source|sourced]] from the sender's high voltage supply,{{efn|1=MIDI nominally uses a +5 volt source, in which case the resistance assignments are R1=R2=R4=220[[Ohm|Ω]] and R3=280Ω. But it is possible to change the resistance values to achieve a similar current with other voltage supplies (in particular, for 3.3 volt systems).}} which travels rightwards along the red lines though the [[Shielded cable|shielded]]{{Efn|The MIDI specification provides for a ground "wire" and a braid or foil shield, connected on the Shield pin, protecting the two signal-carrying conductors on the Hot and Cold pins. Although the MIDI cable is supposed to connect this Shield pin and the braid or foil shield to chassis ground, it should do so only at the MIDI out port; the MIDI in port should leave its Shield pin unconnected and isolated. Some large manufacturers of MIDI devices use modified MIDI in-only DIN 5-pin sockets with the metallic conductors intentionally omitted at pin positions 1, 2, and 3 so that the maximum voltage isolation is obtained.}} [[twisted-pair]] cable and into the receiver's opto-isolator. The current exits the opto-isolator and returns back leftwards along the blue lines into the sender's UART, which [[Current sink|sinks]] the current.{{Efn|It is often easier to use [[NPN transistor|NPN]] or [[Field-effect_transistor#n-channel_FET|nMOS]] transistors to ''sink'' current than to use [[PNP transistor|PNP]] or [[Field-effect_transistor#p-channel_FET|pMOS]] transistors to ''source'' current, because [[electron mobility]] is better than hole mobility.}} [[Resistors]] R1 and R2 limit the current and are equal to provide a [[Balanced line|balanced impedance]]. The [[diode]] is for protection.<ref>{{Cite journal |last=Russ |first=Martin |date=1988-01-01 |title=Practically MIDI (SOS Jan 1988) |url=https://www.muzines.co.uk/articles/practically-midi/3458 |journal=Sound on Sound |issue=Jan 1988 |pages=56–59 |access-date=14 December 2023 |archive-date=14 December 2023 |archive-url=https://web.archive.org/web/20231214192852/https://www.muzines.co.uk/articles/practically-midi/3458 |url-status=live }}</ref> This current turns on the opto-isolator's{{efn|MIDI's original reference design uses the obsolete [[Sharp Corporation|Sharp]] PC900, but modern designs frequently use the 6N138.<ref name="SparkFun" /> The opto-isolator provides [[galvanic isolation]], so there is no conductive path between the two MIDI devices. Properly designed MIDI devices are therefore relatively immune to ground loops and similar interference.}} [[LED]] and [[phototransistor]], so the receiver's UART can read the signal with the help of [[pull-up resistor]] R3 to the receiver's voltage supply. While the supplies in the original specification are 5&nbsp;[[volts]], the receiver and sender may use different voltage levels.

To transmit a logic&nbsp;1, a stop bit, and while idle, the sender's [[UART]] produces the same high voltage as its [[Voltage source|voltage supply]] provides, which results in no current flow. This avoids wasting power when idle.

==Extensions==
MIDI's flexibility and widespread adoption have led to many refinements of the standard, and have enabled its application to purposes beyond those for which it was originally intended.

===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>

===GS, XG, and GM2===
{{Main|General MIDI Level 2|Roland GS|Yamaha XG}}
A general opinion quickly formed that the GM's 128-instrument sound set was not large enough. Roland's General Standard, or [[Roland GS]], included additional sounds, drumkits and effects, provided a ''bank select'' command that could be used to access them, and used MIDI Non-Registered Parameter Numbers (NRPNs) to access its new features. Yamaha's Extended General MIDI, or [[Yamaha XG]], followed in 1994. XG similarly offered extra sounds, drumkits and effects, but used standard controllers instead of NRPNs for editing, and increased polyphony to 32 voices. Both standards feature backward compatibility with the GM specification but are not compatible with each other.<ref>Nagle, Paul. "[http://www.soundonsound.com/sos/1995_articles/sep95/yamahamu50.html Yamaha MU50 & Yamaha CBX-K1] {{webarchive|url=https://web.archive.org/web/20120110140106/http://www.soundonsound.com/sos/1995_articles/sep95/yamahamu50.html |date=10 January 2012 }}". ''Sound on Sound''. SOS Publications. Sep 1995. Print.</ref> Neither standard has been adopted beyond its creator, but both are commonly supported by music software titles.

Member companies of Japan's [[Association of Musical Electronics Industry|AMEI]] developed the [[General MIDI Level 2]] specification in 1999. GM2 maintains backward compatibility with GM, but increases polyphony to 32 voices, standardizes several controller numbers such as for [[sostenuto]] and [[soft pedal]] (''una corda''), RPNs and Universal System Exclusive Messages, and incorporates the MIDI Tuning Standard.<ref>"[http://www.midi.org/techspecs/gm.php About General MIDI] {{webarchive|url=https://web.archive.org/web/20120103100025/http://www.midi.org/techspecs/gm.php |date=3 January 2012 }}". ''midi.org''. MIDI Manufacturers Association. n.d. Web. 17 August 2012</ref> GM2 is the basis of the instrument selection mechanism in Scalable Polyphony MIDI (SP-MIDI), a MIDI variant for low-power devices that allows the device's polyphony to scale according to its processing power.<ref name="Bello" />

===Tuning standard===
{{Main|MIDI tuning standard}}
Most MIDI synthesizers use [[equal temperament]] tuning. The [[MIDI tuning standard]] (MTS), ratified in 1992, allows alternate tunings.<ref name="MTS">"[http://www.microtonal-synthesis.com/MIDItuning.html The MIDI Tuning Standard] {{webarchive|url=https://web.archive.org/web/20121118195344/http://www.microtonal-synthesis.com/MIDItuning.html |date=18 November 2012 }}". ''microtonal-synthesis.com''. n.p. n.d. Web. 17 August 2012</ref> MTS allows [[Microtonal music|microtunings]] that can be loaded from a bank of up to 128 patches, and allows real-time adjustment of note pitches.<ref>{{cite web |url=http://www.midi.org/techspecs/midituning.php |title=MIDI Tuning Messages |publisher=MIDI Manufacturers Association |date=17 August 2012 |archive-url=https://web.archive.org/web/20121130223728/http://www.midi.org/techspecs/midituning.php |archive-date= 30 November 2012 }}</ref> Manufacturers are not required to support the standard. Those who do are not required to implement all of its features.<ref name="MTS" />

===Time code===
{{Main|MIDI timecode}}
A sequencer can drive a MIDI system with its internal clock, but when a system contains multiple sequencers, they must synchronize to a common clock. MIDI timecode (MTC), developed by [[Digidesign]],<ref>Glatt, Jeff. "[http://home.roadrunner.com/~jgglatt/tutr/history.htm The beginnings of MIDI] {{webarchive|url=https://web.archive.org/web/20120501165134/http://home.roadrunner.com/~jgglatt/tutr/history.htm |date=1 May 2012 }}". ''The MIDI Technical Fanatic's Brainwashing Center''. n.p. n.d. Web. 13 August 2012.</ref> implements SysEx messages<ref>Glatt, Jeff. "[http://home.roadrunner.com/~jgglatt/tech/mtc.htm MIDI Time Code] {{webarchive|url=https://web.archive.org/web/20120212181214/http://home.roadrunner.com/~jgglatt/tech/mtc.htm |date=12 February 2012 }}". ''The MIDI Technical Fanatic's Brainwashing Center''. n.p. n.d. Web. 13 August 2012.</ref> developed specifically for timing purposes, and can translate to and from the [[SMPTE timecode]] standard.<ref name="Manning3" />{{rp|288|date=November 2012}} MIDI interfaces such as Mark of the Unicorn's MIDI Timepiece can convert SMPTE code to MTC.<ref>{{cite web |url=http://www.sweetwater.com/publications/sweetnotes/sn-summer96/SumSN_index.html |title="Q & A". ''Sweet Notes''. Sweetwater Sound. Summer 1996. Web |publisher=Sweetwater.com |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20121205031620/http://www.sweetwater.com/publications/sweetnotes/sn-summer96/SumSN_index.html |archive-date=5 December 2012  }}</ref> While MIDI clock is based on tempo, timecode is based on [[Frame (video)|frames]] and is independent of tempo. MTC, like SMPTE timecode, includes position information and can recover in the event of a [[Dropout (communications)|dropout]].<ref>White, Paul. "[http://www.soundonsound.com/sos/1996_articles/jun96/miditimecode.html SMPTE & MTC (MIDI Time Code)] {{webarchive|url=https://web.archive.org/web/20120110105648/http://www.soundonsound.com/sos/1996_articles/jun96/miditimecode.html |date=10 January 2012 }}" ''Sound on Sound''. SOS Publications. Jun 1996. Print.</ref>

===Machine control===
{{Main|MIDI Machine Control}}
MIDI Machine Control (MMC) consists of a set of SysEx commands<ref>Glatt, Jeff. "[http://home.roadrunner.com/~jgglatt/tech/mmc.htm MIDI Machine Control (MMC)] {{webarchive|url=https://web.archive.org/web/20121127041205/http://home.roadrunner.com/~jgglatt/tech/mmc.htm |date=27 November 2012 }}". ''The MIDI Technical Fanatic's Brainwashing Center''. n.p. n.d. Web.</ref> that operate the transport controls of hardware recording devices. MMC lets a sequencer send ''Start'', ''Stop'', and ''Record'' commands to a connected tape deck or hard disk recording system, and to fast-forward or rewind the device to start playback at the same point as the sequencer. No synchronization data is involved, although the devices may synchronize through MTC.<ref>"[http://www.sweetwater.com/expert-center/glossary/t--MMC Glossary: MIDI Machine Control (MMC)] {{webarchive|url=https://web.archive.org/web/20121205031732/http://www.sweetwater.com/expert-center/glossary/t--MMC |date=5 December 2012 }}". ''sweetwater.com''. Sweetwater Sound. n.d. Web. 15 August 2012.</ref>

===Show control===
[[File:Waterworld Plane.jpg|thumb|alt=A theatrical event operated by MIDI Show Control|MIDI Show Control is used to cue and synchronize lighting and effects for theatrical events, such as the [[Waterworld: A Live Sea War Spectacular|Waterworld]] attraction at [[Universal Studios Hollywood]].<ref name="richmondsounddesign.com">"[http://www.richmondsounddesign.com/news.html#hpp News Page] {{webarchive|url=https://web.archive.org/web/20120717095955/http://www.richmondsounddesign.com/news.html |date=17 July 2012 }}". ''richmondsounddesign.com''. Richmond Sound Design, Ltd. 17 July 2012. Web. 17 August 2012</ref>]]
{{Main|MIDI Show Control}}
[[MIDI Show Control]] (MSC) is a set of SysEx commands for sequencing and remotely [[Cue (theatrical)|cueing]] show control devices such as lighting, music and sound playback, and [[motion control]] systems.<ref>"[http://people.virginia.edu/~rlk3p/desource/TechNotes/MSC.html An Inexpensive MIDI show-control System] {{webarchive|url=https://web.archive.org/web/20120621051011/http://people.virginia.edu/~rlk3p/desource/TechNotes/MSC.html |date=21 June 2012 }}". ''Lighting TechNotes''. The University of Virginia. 25 October 2004. Web. 17 August 2012.</ref> Applications include stage productions, museum exhibits, recording studio control systems, and [[amusement park]] attractions.<ref name="richmondsounddesign.com"/>

===Timestamping===
One solution to MIDI timing problems is to mark MIDI events with the times they are to be played, transmit them beforehand, and store them in a buffer in the receiving device. Sending data beforehand reduces the likelihood that a busy passage overwhelms the transmission link. Once stored in the receiver, the information is no longer subject to timing issues associated with MIDI or USB interfaces and can be played with a high degree of accuracy.<ref>"[http://www.sweetwater.com/expert-center/glossary/t--MTS-MOTU Glossary: MTS (MIDI Time Stamping)] {{webarchive|url=https://web.archive.org/web/20121205041728/http://www.sweetwater.com/expert-center/glossary/t--MTS-MOTU |date=5 December 2012 }}". ''sweetwater.com''. Sweetwater Sound. n.d. Web. 17 August 2012</ref> MIDI timestamping only works when both hardware and software support it. MOTU's MTS, eMagic's AMT, and Steinberg's Midex 8 had implementations that were incompatible with each other, and required users to own software and hardware manufactured by the same company to work.<ref name="WalkerTime" /> Timestamping is built into FireWire MIDI interfaces,<ref name="WalkerLate">Walker, Martin. "[http://www.soundonsound.com/sos/Oct02/articles/pcmusician1002.asp The Truth About Latency: Part 2] {{webarchive|url=https://web.archive.org/web/20111225130148/http://www.soundonsound.com/sos/oct02/articles/pcmusician1002.asp |date=25 December 2011 }}". ''Sound on Sound''. SOS Publications. Oct 2002. Print.</ref> Mac OS X [[Core Audio]], and Linux ALSA Sequencer.

===Sample dump standard===
An unforeseen capability of SysEx messages was their use for transporting audio samples between instruments. This led to the development of the sample dump standard (SDS), which established a new SysEx format for sample transmission.<ref name="Manning3" />{{rp|287|date=November 2012}} SDS was later augmented with a pair of commands that allow the transmission of information about sample loop points, without requiring that the entire sample be transmitted.<ref>Glatt, Jeff. [https://web.archive.org/web/20111115234241/http://home.roadrunner.com/~jgglatt/tech/sds.htm]. ''The MIDI Technical Fanatic's Brainwashing Center''. n.p. n.d. Web. 13 August 2012.</ref>

===Downloadable Sounds===
{{Main|DLS format}}
The Downloadable Sounds (DLS) specification, ratified in 1997, allows mobile devices and computer [[sound card]]s to expand their wave tables with downloadable sound sets.<ref>{{cite web |url=http://www.midi.org/techspecs/dls/dlsoverview.php |title=Massey, Howard. "DLS Overview". ''midi.org''. n.d. Web. 27 Aug 2012 |publisher=Midi.org |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20121127083133/http://www.midi.org/techspecs/dls/dlsoverview.php |archive-date=27 November 2012  }}</ref> The DLS Level 2 specification followed in 2006, and defined a standardized synthesizer architecture. The Mobile DLS standard calls for DLS banks to be combined with SP-MIDI, as self-contained Mobile XMF files.<ref>{{cite web |url=http://www.midi.org/techspecs/dls/dls.php |title="DLS 1 Spec". ''midi.org''. n.d. Web. 27 Aug 2012 |publisher=Midi.org |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20121130114614/http://www.midi.org/techspecs/dls/dls.php |archive-date=30 November 2012  }}</ref>

===MIDI Polyphonic Expression===
MIDI Polyphonic Expression (MPE) is a method of using MIDI that enables pitch bend, and other dimensions of expressive control, to be adjusted continuously for individual notes.<ref name=MPE2018>{{cite web|url=https://www.midi.org/articles/midi-polyphonic-expression-mpe|title=MIDI Polyphonic Expression (MPE) Specification Adopted!|last=MIDI Manufacturers Association|date=January 2018|access-date=12 February 2018|archive-url=https://web.archive.org/web/20171102162057/https://www.midi.org/articles/midi-polyphonic-expression-mpe|archive-date=2 November 2017}}</ref> MPE works by assigning each note to its own MIDI channel so that controller messages can be applied to each note individually.<ref>{{cite web|last=Linn|first=Roger|url=http://www.rogerlinndesign.com/implementing-mpe.html|title=For Developers of MIDI Sound Generators: How to add MPE Capability|access-date=8 September 2016|url-status=live|archive-url=https://web.archive.org/web/20160917131941/http://www.rogerlinndesign.com/implementing-mpe.html|archive-date=17 September 2016}}</ref><ref name=MPE2018/> The specifications were released in November 2017 by AMEI and in January 2018 by the MMA.<ref name=MIDI-CI2018>{{cite web|url=https://www.midi.org/articles-old/midi-manufacturers-association-mma-adopts-midi-capability-inquiry-midi-ci-specification|title=MIDI Manufacturers Association (MMA) Adopts MIDI Capability Inquiry (MIDI-CI) Specification.|website=www.midi.org|access-date=13 September 2018|archive-date=23 January 2019|archive-url=https://web.archive.org/web/20190123165200/https://www.midi.org/articles-old/midi-manufacturers-association-mma-adopts-midi-capability-inquiry-midi-ci-specification|url-status=dead}}</ref> Instruments like the [[Continuum Fingerboard]], [[LinnStrument]], [[ROLI Seaboard]], [[Sensel]] Morph, and [[Eigenharp]] let users control pitch, timbre, and other nuances for individual notes within chords.<ref>{{cite web |last1=Robair |first1=Gino |title=Three pioneers discuss Multidimensional Polyphonic Expression |url=https://roli.com/article/mpe-in-emusician?region=uk |website=ROLI |publisher=Electronic Musician |access-date=10 January 2019 |archive-date=11 January 2019 |archive-url=https://web.archive.org/web/20190111060618/https://roli.com/article/mpe-in-emusician?region=uk |url-status=dead }}</ref>

==Alternative hardware transports==
In addition to using a 31.25&nbsp;kbit/s current-loop over a [[DIN connector]], the same data can be transmitted over different hardware transports such as [[USB]], [[FireWire]], and [[Ethernet]].

===USB and FireWire===
Members of the USB-IF in 1999 developed a standard for MIDI over USB, the "Universal Serial Bus Device Class Definition for MIDI Devices".<ref>Ashour, Gal, et al. [http://www.usb.org/developers/docs/devclass_docs/midi10.pdf "Universal Serial Bus Device Class Definition for MIDI Devices"]. ''USB Implementers Forum''. {{webarchive|url=https://web.archive.org/web/20150426221331/http://www.usb.org/developers/docs/devclass_docs/midi10.pdf |date=26 April 2015 }}. 1 November 1999. Accessed 22 August 2012.</ref> MIDI over USB has become increasingly common as other interfaces that had been used for MIDI connections ([[ISA card]], [[game port]], etc.) disappeared from personal computers. Linux, Microsoft Windows, Macintosh OS X, and Apple iOS operating systems include [[USB device class|standard class]] drivers to support devices that use the "Universal Serial Bus Device Class Definition for MIDI Devices".

[[Apple Computer]] developed the FireWire interface during the 1990s. It began to appear on [[DV (video format)#Connectivity|digital video]] (DV) cameras toward the end of the decade, and on G3 Macintosh models in 1999.<ref name="WiffenFW1">Wiffen, Paul. "[http://www.soundonsound.com/sos/aug00/articles/mlan.htm An Introduction To mLAN, Part 1]". {{webarchive|url=https://web.archive.org/web/20160102133428/http://www.soundonsound.com/sos/aug00/articles/mlan.htm |date=2 January 2016 }}. ''Sound on Sound''. SOS Publications. August 2000.</ref> It was created for use with multimedia applications.<ref name="WalkerLate" /> Unlike USB, FireWire uses intelligent controllers that can manage their own transmission without attention from the main CPU.<ref name="WiffenFW2">Wiffen, Paul. "[http://www.soundonsound.com/sos/sep00/articles/mlan.htm An Introduction To mLAN, Part 2]". {{webarchive|url=https://web.archive.org/web/20120110210330/http://www.soundonsound.com/sos/sep00/articles/mlan.htm |date=10 January 2012 }}. ''Sound on Sound''. SOS Publications. September 2000.</ref> As with standard MIDI devices, FireWire devices can communicate with each other with no computer present.<ref name="Cables" />

===XLR connectors===
The Octave-Plateau [[Voyetra-8]] synthesizer was an early MIDI implementation using [[XLR connector#XLR3 connectors|XLR3 connectors]] in place of the [[DIN connector|5-pin DIN]]. It was released in the pre-MIDI years and later retrofitted with a MIDI interface but kept its XLR connector.<ref>{{cite web |last=Vail |first=Mark |title=Voyetra 8: The original rackmount analog polysynth |url=http://www.turtlebeach.com/support/entry/830517138/ |work=Keyboard Magazine |publisher=Turtle Beach |archive-url=https://archive.today/20130630120411/http://www.turtlebeach.com/support/entry/830517138/ |archive-date=30 June 2013}}</ref>

==== Serial parallel, and joystick port ====
As computer-based studio setups became common, MIDI devices that could connect directly to a computer became available. These typically used the [[Mini DIN-8|8-pin mini-DIN]] connector that was used by Apple for [[serial port]]s prior to the introduction of the [[Blue and White G3]] models. MIDI interfaces intended for use as the centerpiece of a studio, such as the [[Mark of the Unicorn]] MIDI Time Piece, were made possible by a fast transmission mode that could take advantage of these serial ports' ability to operate at 20 times the standard MIDI speed.<ref name="Huber 1991"/>{{rp|62–3|date=November 2012}}<ref name="Cables">"[http://www.midi.org/aboutmidi/tut_midicables.php MIDI Cables & Transports] {{webarchive|url=https://web.archive.org/web/20121104052816/http://www.midi.org/aboutmidi/tut_midicables.php |date=4 November 2012 }}". ''midi.org''. Music Manufacturers Association. n.d. Web. 27 August 2012.</ref> Mini-DIN ports were built into some late-1990s MIDI instruments and enabled such devices to be connected directly to a computer.<ref>"CS2x Control Synthesizer Owner's Manual". Yamaha Corporation, 1998.</ref> Some devices connected via a PCs' [[DB-25 parallel port]], or through the [[DA-15 game port]] found on many PC sound cards.<ref name="Cables" />

====mLAN====
[[Yamaha Corporation|Yamaha]] introduced the [[mLAN]] protocol in 1999. It was conceived as a [[local area network]] for musical instruments using FireWire as the transport and was designed to carry multiple MIDI channels together with multichannel digital audio, data file transfers, and timecode.<ref name="WiffenFW1" /><ref name="WiffenFW2" /> mLan was used in a number of Yamaha products, notably [[digital mixing console]]s and the [[Yamaha Motif|Motif]] synthesizer, and in third-party products such as the PreSonus FIREstation and the [[Korg Triton Studio]].<ref>{{cite web |url=http://www.presonus.com/products/FIREstation |title="PreSonus FIREstation". ''presonus.com''. n.p. n.d. Web. 18 Aug 2012 |publisher=Presonus.com |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20121231140519/http://www.presonus.com/products/FIREstation |archive-date=31 December 2012  }}</ref> No new mLan products have been released since 2007.

=== SCSI MIDI Device Interface (SMDI) ===
[[SCSI]] MIDI Device Interface (SMDI) was used by some samplers and [[hard disk recorder]]s in the 1990s (e.g. [[Kurzweil K2000]] and [[Peavey Electronics|Peavey]] SP Sample Playback Synthesizer<ref>{{Cite journal |last=Trask |first=Simon |date=1992 |title=Peavey SP Sample Playback Synthesiser |url=https://www.muzines.co.uk/articles/peavey-sp-sample-playback-synthesiser/2341 |url-status=live |journal=Music Technology |issue=Aug 1992 |pages=52–56 |archive-url=https://web.archive.org/web/20210516182228/https://www.muzines.co.uk/articles/peavey-sp-sample-playback-synthesiser/2341 |archive-date=2021-05-16}}</ref>) for fast bidirectional sample transport to [[hard disk drives]] and [[magneto-optical drive]]s.<ref>{{Cite web |last=Walker |first=Martin |date=1996 |title=Integrating Samplers & Your PC Via SCSI |url=https://www.soundonsound.com/techniques/integrating-samplers-your-pc-scsi |url-status=live |archive-url=https://web.archive.org/web/20231222164723/https://www.soundonsound.com/techniques/integrating-samplers-your-pc-scsi |archive-date=2023-12-22 |access-date=2023-12-22 |website=[[Sound on Sound]]}}</ref><ref>{{Cite web |last=Sweetwater |date=1999-04-23 |title=SMDI |url=https://www.sweetwater.com/insync/smdi/ |url-status=live |archive-url=https://web.archive.org/web/20151005133122/http://www.sweetwater.com/insync/smdi/ |archive-date=2015-10-05 |access-date=2023-12-22 |website=inSync |language=en}}</ref>

===Ethernet and Internet Protocol===
[[Computer network]] implementations of MIDI provide network routing capabilities, and the high-bandwidth channel that earlier alternatives to MIDI, such as [[ZIPI]], were intended to bring. Proprietary implementations have existed since the 1980s, some of which use [[fiber optic]] cables for transmission.<ref name="Huber 1991" />{{rp|53–4|date=November 2012}} The [[Internet Engineering Task Force]]'s [[RTP-MIDI]] open specification has gained industry support. Apple has supported this protocol from [[Mac OS X]] 10.4 onwards, and a [[Windows]] driver based on Apple's implementation exists for Windows XP and newer versions.<ref>"rtpMIDI". ''tobias-erichsen.de''. n.p. n.d. Web. 22 August 2012 [http://www.tobias-erichsen.de/software/rtpmidi.html Windows RTP-MIDI driver download] {{webarchive|url=https://web.archive.org/web/20120816032555/http://www.tobias-erichsen.de/software/rtpmidi.html |date=16 August 2012 }}</ref>

===Wireless===
Systems for wireless MIDI transmission have been available since the 1980s.<ref name="Huber 1991" />{{rp|44|date=November 2012}} Several commercially available transmitters allow wireless transmission of MIDI and [[Open Sound Control|OSC]] signals over [[Wi-Fi]] and [[Bluetooth]].<ref>Kirn, Peter. "[http://createdigitalmusic.com/2011/03/golden-age-of-wireless-korg-ios-sync-android-midi-hardware-enter-bluetooth-midi/ Golden Age of Wireless: Korg iOS Sync, Android + MIDI Hardware, Enter Bluetooth MIDI?] {{webarchive|url=https://web.archive.org/web/20120911130151/http://createdigitalmusic.com/2011/03/golden-age-of-wireless-korg-ios-sync-android-midi-hardware-enter-bluetooth-midi/ |date=11 September 2012 }}". ''createdigitalmusic.com''. n.p. 25 March 2011. Web.</ref> iOS devices are able to function as MIDI control surfaces, using Wi-Fi and OSC.<ref>{{cite web |url=http://hexler.net/software/touchosc |title="TouchOSC". ''hexler.net'' n.p. n.d. Web. 20 Aug 2012 |publisher=Hexler.net |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20121205071535/http://hexler.net/software/touchosc |archive-date=5 December 2012  }}</ref> An [[XBee]] radio can be used to build a wireless MIDI transceiver as a do-it-yourself project.<ref>"[http://ladyada.net/make/xbee/midibee.html XBee Adapter&nbsp;– wireless Arduino programming] {{webarchive|url=https://web.archive.org/web/20120602152151/http://www.ladyada.net/make/xbee/midibee.html |date=2 June 2012 }}". ''ladyada.net''. n.p. 17 May 2011. Web. 20 August 2012.</ref> Android devices are able to function as full MIDI control surfaces using several different protocols over [[Wi-Fi]] and [[Bluetooth]].<ref>{{cite web|url=http://www.humatic.de/htools/touchdaw/|title=TouchDAW – DAW controller and MIDI utilities for Android™|access-date=31 August 2016|url-status=live|archive-url=https://web.archive.org/web/20160907160204/http://www.humatic.de/htools/touchdaw/|archive-date=7 September 2016}}</ref>

==MIDI 2.0==
{{Excerpt|MIDI 2.0}}

==See also==
{{Portal|music}}
* [[ABC notation]]
* [[Digital piano]]
* [[Electronic drum module]]
* [[Guitar synthesizer]]
* [[List of music software]]
* [[MIDI mockup]]
* [[MusicXML]]
* [[Music Macro Language]]
* [[SoundFont]]
* [[Synthetic music mobile application format]]

==Notes==
{{Notelist}}

==References==
{{Reflist|refs=
<ref name="russ2012">{{cite book |last=Russ |first=Martin |year=2012 |title=Sound Synthesis and Sampling |url=https://books.google.com/books?id=X9h5AgAAQBAJ&pg=PA192 |publisher=[[CRC Press]] |isbn= 978-1-136-12214-9 |page=192 |access-date=26 April 2017 |url-status=live |archive-url=https://web.archive.org/web/20170428051514/https://books.google.co.uk/books?id=X9h5AgAAQBAJ&pg=PA192 |archive-date=28 April 2017 }}</ref>
<ref name="casabona">{{cite book|url=https://books.google.com/books?id=6K5Tpl_zBoEC&pg=PA15 |url-status=live |title=Advanced MIDI Applications |author1=Helen Casabona |author2=David Frederick |publisher=[[Alfred Music]] |isbn=978-1-4574-3893-6 |page=15 |archive-url=https://web.archive.org/web/20171026003030/https://books.google.co.uk/books?id=6K5Tpl_zBoEC&pg=PA15 |archive-date=26 October 2017}}</ref>
<ref name="emusician-mpu">[http://www.textfiles.com/music/midi-em.txt MIDI INTERFACES FOR THE IBM PC] {{webarchive|url=https://web.archive.org/web/20151021050032/http://textfiles.com/music/midi-em.txt |date=21 October 2015 }}, ''[[Electronic Musician]]'', September 1990</ref>
}}<!--[[User:Kvng/RTH]]-->

==External links==
<!-- Note: Any links added to this section should contain material about the technical aspects of MIDI. Please do not add links to sites offering MIDI files or advertising websites. Thank you.-->
* [https://www.midi.org/ The MIDI Association] {{Webarchive|url=https://web.archive.org/web/20180219070411/https://www.midi.org/ |date=19 February 2018 }}
* [https://midi.org/specs You can download English-language MIDI specifications] {{Webarchive|url=https://web.archive.org/web/20160601121904/https://www.midi.org/specifications |date=1 June 2016 }} at the [[MIDI Manufacturers Association]]

{{Computer bus}}
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{{Digital audio and video protocols}}
{{Authority control}}

[[Category:MIDI| ]]
[[Category:Computer hardware standards]]
[[Category:Electronic music]]
[[Category:Japanese inventions]]
[[Category:Serial buses]]