Editing MIDI (section)

==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.