Musical Instrument Digital Interface

Musical Instrument Digital Interface
Name	Musical Instrument Digital Interface
Abbreviation	MIDI
Introduced	1983
Developer	Dave Smith; Ikutaro Kakehashi
Type	Digital communication protocol

Musical Instrument Digital Interface

Musical Instrument Digital Interface is a standardized protocol for interconnecting electronic synthesizers, electronic drums, personal computers, sequencers, and other electronic musical instruments to control performance data and synchronize timing. It was developed in the early 1980s to enable interoperability among products from manufacturers such as Roland Corporation, Yamaha Corporation, Korg, and Sequential Circuits. The specification influenced the design of hardware and software across the music technology industry, shaping workflows in studios, live performance, and education at institutions like the Berklee College of Music and the Juilliard School.

History

Development began when engineers including Dave Smith of Sequential Circuits and Ikutaro Kakehashi of Roland Corporation sought a common control interface amid competing interfaces used by companies such as Moog Music and Oberheim Electronics. Early demonstrations at trade shows like the NAMM Show facilitated adoption by manufacturers including Korg and Yamaha Corporation. The first public specification appeared in 1983, with influential products such as the Roland TR-808 and the Sequential Circuits Prophet-600 integrating the protocol. Organizations like the MIDI Manufacturers Association and standards bodies such as the Association of Musical Electronics Industry later maintained revisions and extensions. Milestones include the introduction of General MIDI by the MIDI Manufacturers Association and the later development of audio-focused standards influenced by the protocol at conferences like AES Convention.

Technical Specifications

The protocol defines a serial, asynchronous, byte-oriented data stream with a default bit rate of 31,250 bits per second, transmitted over physical layers originally using 5-pin DIN connectors adopted by Roland Corporation and others. The specification enumerates message formats, status bytes, and data bytes, with channelized routing across sixteen logical channels allowing devices like the Yamaha DX7 to share a single bus. Later extensions specified higher-resolution control using Registered Parameter Number schemes, System Exclusive messages for manufacturer-specific payloads used by firms such as Korg and Roland Corporation, and timecode synchronization with standards like SMPTE for integration in film post-production workflows at studios including Skywalker Sound.

Message Types and Protocols

Core messages include Note On, Note Off, Polyphonic Key Pressure, Control Change, Program Change, Channel Pressure, Pitch Bend, and System messages. Control Change messages map to controllers such as the sustain pedal used on instruments designed by Kawai Musical Instruments or expression controls on modules from Kurzweil Music Systems. System Exclusive messages permit proprietary data exchange for devices like the Ensoniq sampler, while System Real-Time messages manage timing synchronization among devices like Akai samplers and Roland TR-909 drum machines. Protocols for file interchange, such as Standard MIDI Files, enabled composers to exchange scores and sequences between software from companies like Emagic and Steinberg.

Hardware and Connectors

Original hardware used 5-pin 180° DIN connectors on devices by Roland Corporation, Yamaha Corporation, and Korg, with dedicated IN, OUT, and THRU ports to facilitate daisy chaining in setups employed by artists like Herbie Hancock and Jean-Michel Jarre. Later transportation methods introduced USB-MIDI as adopted by Apple Inc. and Microsoft Corporation on personal computers and controllers from Novation and M-Audio. Alternative transmission media include MIDI over Ethernet used in installations by firms such as Bose Corporation and wireless solutions created by manufacturers including Yamaha Corporation and independent developers displaying products at the NAMM Show.

Software and Implementations

Software hosts, digital audio workstations and sequencers such as Pro Tools, Ableton Live, Cubase, Logic Pro, and FL Studio integrate MIDI routing, editing, and mapping for virtual instruments like those from Native Instruments and Spectrasonics. Notation programs from Avid Technology and Sibelius import and export Standard MIDI Files to exchange data with hardware sequencers from the era of Atari ST and modern controllers like those by Akai Professional. Firmware and driver development for platforms such as Microsoft Windows, macOS, and Linux provide low-level support, while ecosystems including Max/MSP and Pure Data enable bespoke processing and generative composition workflows used by artists at festivals such as IMEA.

Applications and Use Cases

MIDI underpins studio production chains at facilities like Abbey Road Studios and live performance rigs used by bands including Pink Floyd and Radiohead, enabling synchronization between synthesizers, drum machines, and lighting controllers from companies like MA Lighting. It supports composition and arrangement in educational programs at institutions such as the Royal College of Music and commercial scoring for film and television at studios like Warner Bros. and BBC Studios where SMPTE integration is critical. Interactive installations in museums like the Museum of Modern Art and game audio workflows at developers such as Nintendo and Electronic Arts also leverage MIDI for control tasks.

Legacy and Future Developments

MIDI's influence extends to modern standards and initiatives like MIDI 2.0 driven by industry groups including the MIDI Association and large manufacturers such as Roland Corporation and Yamaha Corporation. Enhancements aim to increase resolution, bidirectional capability, and profile-based interoperability to meet requirements of next-generation instruments from firms like Sequential Circuits' successors and boutique builders showcased at the NAMM Show. Its legacy persists in the practices of studios, conservatories, and electronic instrument designers at companies such as Korg and Moog Music, while ongoing standardization work engages organizations including the MIDI Manufacturers Association and the Audio Engineering Society.

Category:Computer music