What is the function of MIDI?

MIDI stands for “Musical Instrument Digital Interface.” It is a technical standard, protocol and file format that allows communication, synchronization, and control between digital musical instruments, computers, smartphones and other electronic devices.

The main purpose of MIDI is to connect digital musical instruments together and allow different devices to communicate with each other. This enables synchronization between devices so that multiple instruments can play together in a coordinated way. It also allows for remote control of instruments and sharing of data like musical notes, tempo, vibrato and panning between devices.

Overall, MIDI acts as a common language and standard that enables interoperability between electronic music devices from different manufacturers. It allows for a wide range of musical applications, streaming of MIDI data over networks, and recording and playing back of MIDI data using sequencer software.

Brief History of MIDI Development

MIDI stands for Musical Instrument Digital Interface and was invented by Dave Smith and Ikutaro Kakehashi in the early 1980s. The motivation behind its development was to create a standard protocol that could connect different electronic music technologies and allow them to communicate with each other.

Some key events in the history of MIDI include:

In 1981, Dave Smith (Sequential Circuits) and Ikutaro Kakehashi (Roland Corporation) began working together on ideas for standardizing communication between electronic music devices.

In 1982, the first MIDI instruments were introduced at the NAMM trade show, including the Prophet 600 synthesizer with MIDI implementation designed by Smith.
In 1983, the MIDI 1.0 specification was officially released by the MIDI Manufacturers Association, establishing the MIDI protocol.
In 1991, General MIDI standard was established, which provided standardized program numbers for different instrument sounds.

MIDI allowed synthesizers, keyboards, drum machines and other hardware to be interconnected and synchronize with each other. This was revolutionary in the music world, enabling greater creativity in electronic music production and performance.

Source: https://www.perfectcircuit.com/signal/history-of-midi

How MIDI Works Technically

MIDI stands for Musical Instrument Digital Interface. It allows electronic musical instruments, computers, and other devices to communicate and synchronize with each other. MIDI sends messages between devices serially using 5-pin DIN connectors and cables.

The messages transmitted via MIDI include note-ons, note-offs, program change messages, control signals, and more. Note-ons and note-offs tell instruments which notes to start and stop playing. Program change messages allow patches and sounds to be selected on synthesizers. Control signals can modify sounds by changing parameters like volume, panning, vibrato, and other effects.

The data in a MIDI message contains event information, timing information, and sequencer data. The event data specifies the type of message, which note to play, which patch to select, etc. The timing data provides the exact timing of when the events should happen based on a consistent tempo and time signature. Sequencer data allows sequencing and arrangement information to be stored alongside the notes.

By transmitting these various types of musical data between devices in a standard format, MIDI revolutionized electronic music production, enabling complex arrangements between synths, drum machines, samplers, computers, and more. Without MIDI’s standard protocol, this level of sophistication between musical devices would not be possible.

Source: https://www.sweetwater.com/insync/midi-essential-guide/

MIDI Applications and Uses

MIDI was originally designed to connect synthesizers, keyboards, and electronic drum machines together to synchronize timing and allow them to be played or sequenced from a central controller or sequencer. The primary applications and uses of MIDI include:

Playing and controlling synthesizers, keyboards, drum machines
– A MIDI keyboard controller or other MIDI device can play internal sounds and control parameters on a sound module or synthesizer. This allows musicians to play electronic instruments from a central location.

Sequencing melodies and rhythms into complete compositions
– MIDI data can be recorded into and played back from a hardware or software sequencer in order to create full songs by layering tracks. Sequencing allows crafting compositions with multiple instruments.

Synchronizing timing between instruments and devices.
– MIDI Clock messages synchronize tempo, beat and rhythm across multiple devices like drum machines, arpeggiators and sequencers. This tempo sync ensures everything stays in time.

Beyond these core uses, MIDI data can also be used for lighting control, show control, and a wide variety of other applications where time-synchronized binary data transmission is required. The versatility and ubiquity of MIDI has led to its adoption far beyond its original purpose in music production.

Types of MIDI Messages

There are three main types of MIDI messages as defined in the MIDI 1.0 specification:

Channel Messages

Channel messages are sent over one of 16 MIDI channels and involve the basic MIDI data like notes, controllers, program changes etc. Some examples include (Summary of MIDI 1.0 Messages):

Note on – Sent when a note is pressed on a MIDI keyboard.

Note off – Sent when a key is released on a MIDI keyboard.
Polyphonic key pressure – Data related to pressure/velocity on a MIDI keyboard key.
Controller changes – Sent when a controller like modulation wheel, sustain pedal etc. is operated.

Program change – Sent when a new instrument/sound patch is selected.

System Messages

System messages relate to overall MIDI system real-time behavior and synchronization like start/stop commands, timing and song position. Some examples (
About MIDI Part 3) include:

Timing clock – Regular pulses for tempo/synchronization.

Start/Stop – Start or stop a sequence/pattern.
Song position pointer – Provide current position in song playback.

System Exclusive Messages

These proprietary messages contain instrument-specific data like patch editing, waveform data etc. They enable manufacturers to go beyond the standard MIDI spec and control their own synth parameters.

MIDI File Format (.mid)

MIDI files have the file extension .mid and contain a series of MIDI event messages that digital musical instruments like synthesizers and samplers can play back. Unlike regular audio files, MIDI files do not contain any actual audio data and are therefore very compact in file size.

According to the Standard MIDI File Format Spec 1.1 from McGill University’s Music Technology Area (source), a MIDI file is simply a series of 8-bit bytes from the perspective of a file system. This compact byte stream can be easily stored, transferred and played back across different systems and platforms, making the MIDI format highly portable and compatible.

Due to its small file size and universal compatibility, the MIDI file format (.mid) has remained an essential component of digital music production, notation and sequencing for decades. MIDI files allow musicians to share musical ideas and compositions without being constrained by audio recordings or specific hardware limitations.

Standard MIDI Files

MIDI files are stored in a Standard MIDI File (SMF) format, which was first published in 1991. There are 3 main types of SMF formats:

Format 0: All MIDI data is stored in a single track. This format is used for shorter, single-instrument pieces. All events are stored sequentially based on their timing.

Format 1: In this format, MIDI data is stored with one track per MIDI channel. This allows greater flexibility in working with multiple instruments/channels. Each track contains only the channel messages for that specific instrument or voice. This is useful for multi-track recording and sequencing.

Format 2: This format supports multiple tracks for larger, more complex compositions. It is used when there are a large number of instruments and synchronizing data between them is required. Each track can have its own time signature and tempo map. This provides more control over the arrangement of the composition.

The SMF format preserves the MIDI performance information and allows it to be saved, transported between devices, and accurately reproduced by MIDI-capable devices.

Sources:

http://www.music.mcgill.ca/~ich/classes/mumt306/StandardMIDIfileformat.html

https://en.wikipedia.org/wiki/MIDI

MIDI Capabilities

One of the key capabilities of MIDI is the ability to transmit musical data over up to 16 independent channels per MIDI connection. This allows a single MIDI cable to carry the data for up to 16 different instruments or devices simultaneously. Each device can be assigned to listen and respond to a specific MIDI channel, keeping the data separate. This is essential for recording multi-track compositions using MIDI.

In addition, up to 128 MIDI devices can be daisy-chained together using MIDI thru connections. This allows a MIDI setup to control a large number of synthesizers, sound modules, and other gear from a central MIDI controller or sequencer. By assigning each device to a different MIDI channel, they can all receive independent control and performance data over a single MIDI cable chain.

MIDI also allows for the control of a wide range of musical parameters beyond just note on/off and pitch. Standard MIDI messages exist for modulating sound parameters like volume, panning, vibrato, filter settings, and many more. This facilitates detailed shaping of sound and expression. MIDI controller devices feature knobs, sliders, ribbons, and other controls that can map to these various MIDI control messages. This provides users with tactile control over sound synthesis and manipulation when performing or producing music.

According to discussions on Reddit (https://www.reddit.com/r/synthesizers/comments/14kece2/looking_for_a_midi_controller_with_zones/), advanced MIDI controllers also allow for zone splitting, where different regions of a keyboard can send MIDI to different channels. This expands the creative flexibility of MIDI setups even further.

MIDI Limitations

MIDI has some inherent technical limitations that can affect its usage in music production and performance:

MIDI has a relatively limited data bandwidth and speed. The MIDI protocol can only transmit about 3,000 MIDI events per second, which limits how much simultaneous note and controller data it can handle. This can make it challenging to control and sequence highly complex, dense arrangements with lots of MIDI data (https://eimearclarke.wordpress.com/2015/03/13/limitations-of-midi-technology/).

The MIDI protocol also introduces latency, which is a short delay between triggering a MIDI note and hearing the sound. This latency builds up when using multiple MIDI devices chained together. While often negligible in the studio, latency can cause timing issues during live performances when musicians are monitoring MIDI instruments in real-time (https://producersociety.com/pros-cons-midi/).

Unlike an audio file, MIDI does not contain any actual sound or audio data. MIDI simply transmits performance instructions to an external sound module or software instrument, which must then be converted to audio through a digital-to-analog (D/A) converter. The quality of the final sound depends entirely on the capabilities of the sound module. MIDI playback can sometimes sound unnatural or unrealistic compared to a high-quality audio recording (https://www.linkedin.com/advice/0/what-advantages-disadvantages-using-midi-vs-audio).

The Future of MIDI

Despite being developed in the early 1980s, MIDI continues to play a central role in music production and performance. New protocols that build on MIDI’s strengths, like Audio over IP, USB-MIDI, and the recently announced MIDI 2.0 specification, demonstrate its continued relevance for contemporary digital music workflows.

The MIDI 2.0 specification represents the first major update to the MIDI standard in over 30 years. Announced in early 2020, MIDI 2.0 aims to dramatically increase MIDI’s resolution and expand its capabilities into areas like program automation and enriched semantics. As described in an article on MusicRadar, “MIDI 2.0 is set to be the biggest advance in music technology in decades.”

By providing 32,768 levels of resolution (a nearly 8000% increase), MIDI 2.0 will enable far more nuanced and expressive performances. Other additions like Profile Configurations and Property Exchange introduce new levels of customization and flexibility. While backwards compatible with traditional MIDI, MIDI 2.0 is positioned to provide the foundation for innovative music technologies well into the future.

In summary, despite its age, MIDI continues to evolve and provide core functionality for a wide range of music applications. With the pending arrival of MIDI 2.0 and related protocols, MIDI’s relevance seems assured for years to come.