MIDI

MIDI
Blurred Ren · CC BY 2.0 · source
Name	MIDI
Caption	MIDI connector and keyboard
Introduced	1983
Developers	Dave Smith, Ikutaro Kakehashi
Type	Technical standard
Related	General MIDI, USB, DIN connector

MIDI MIDI is a technical standard for communication, control, and interchange among electronic musical instruments, computers, and related devices. It specifies a binary protocol, electrical connectors, and messaging conventions enabling devices from different manufacturers to interoperate, often in live performance, studio production, and music education. The standard emerged through collaboration among instrument makers and digital pioneers and has been extended across decades by manufacturers, software developers, and music technologists.

History

Development began in the late 1970s and early 1980s when companies such as Sequential Circuits, Roland Corporation, Korg, and Yamaha Corporation sought interoperability between synthesizers like the Prophet-5 and modular systems. Key figures include Dave Smith of Sequential Circuits and Ikutaro Kakehashi of Roland Corporation, who led industry workshops and vendor meetings culminating in a published standard in 1983. Early demonstrations at trade shows like the NAMM Show helped drive rapid adoption by manufacturers such as Akai, Korg, Yamaha Corporation, Roland Corporation, and Casio; this enabled ecosystems around hardware sequencers, drum machines, and workstations. Organizations including the MIDI Manufacturers Association later formalized revisions and extensions to address evolving needs in digital audio and computing, with integration into platforms from Apple Inc. and Microsoft shaping adoption in studios and consumer markets worldwide.

Technical specifications

The standard defines a serial, asynchronous, 31.25 kbaud, 8-N-1 physical layer using 5-pin DIN connector cables for the original electrical interface, enabling one-to-many daisy-chained topologies and opto-isolation to prevent ground loops. The protocol arranges data into status bytes and data bytes; status bytes identify message types and channels while data bytes convey parameters such as note number, velocity, and control change values. Channelized messaging supports 16 logical channels per port, and additional standards like General MIDI specify preset mappings and drum channels for consistent playback across compatible devices. Later transport mechanisms encapsulate the protocol over interfaces like USB, Ethernet, and IEEE 1394 while preserving message semantics for compatibility with legacy devices.

MIDI messages and protocols

Message types include Channel Voice Messages (note on, note off, polyphonic key pressure), Channel Mode Messages, System Common Messages (song position pointer, song select), System Real-Time Messages (timing clock, start, stop), and System Exclusive messages used for manufacturer-specific parameter dumps. Standardized controllers (modulation wheel, sustain pedal, volume) map to controller numbers, whereas Program Change messages select instrument patches on devices by program number. The protocol handles running status to reduce bandwidth, uses a 7-bit data payload for most parameters, and supports 14-bit values via paired Most Significant Byte/Least Significant Byte constructs for higher-resolution parameters. Extensions such as the MIDI Show Control protocol and the MIDI Time Code integrate show control and synchronization with timecode systems used in film and broadcast workflows.

Hardware and devices

Hardware devices include keyboards, synthesizers, sound modules, drum machines, sequencers, effects processors, and controllers from manufacturers like Roland Corporation, Yamaha Corporation, Korg, Akai, and Nord Keyboards. Interfaces range from dedicated MIDI interfaces produced by companies such as MOTU and M-Audio to integrated ports on digital audio workstations and mobile devices from Apple Inc. and Microsoft. Cable topologies include MIDI Thru chains, merge boxes, and patch bays; studio environments often combine hardware routers, USB hubs, and network devices to interconnect legacy and modern gear. Vintage instruments such as the Jupiter-8 and TR-808 retain relevance through their MIDI implementations and modern retrofit kits offered by boutique manufacturers.

Software and applications

Software spans sequencers, digital audio workstations (DAWs) like Avid's Pro Tools, Steinberg's Cubase, Ableton Live, score editors, virtual instruments, and notation tools from companies including Native Instruments, Spectrasonics, and Cakewalk. Applications use MIDI for composition, arrangement, live looping, and automated control of effects and lighting consoles such as products from MA Lighting and Electronic Theatre Controls. Libraries and frameworks for C++, Java, Python, and JavaScript facilitate MIDI integration into custom software, mobile apps, and interactive installations deployed in venues like concert halls and museums.

Adoption and influence

The standard’s ubiquity transformed instrument design, enabling modular studio configurations, multi-timbral workstations, and hardware/software hybrid setups adopted by artists, producers, and educators worldwide. It influenced genres and production techniques used by performers associated with labels and studios such as Motown Records, Sun Records, and Abbey Road Studios, and played roles in live touring rigs for acts that used complex show control. Institutions including conservatories and music technology programs incorporated the protocol into curricula, while trade organizations like the MIDI Manufacturers Association and trade events such as the NAMM Show foster ongoing interoperability efforts.

Variations and extensions

Multiple extensions augment the core protocol: General MIDI standardizes patch maps and percussion channel assignments; MIDI Show Control addresses theatrical and production workflows; MIDI Time Code and the MIDI Machine Control protocol handle synchronization and transport control with tape and DAW systems. Manufacturer-specific System Exclusive messages permit detailed parameter editing and firmware updates by companies such as Roland Corporation, Korg, and Yamaha Corporation. Recent initiatives like the development of higher-resolution protocols, the adoption of USB-MIDI class drivers, and networked solutions promoted by organizations including the MIDI Manufacturers Association aim to modernize throughput, timing, and routing for contemporary studio and live-production demands.

Category:Music technology