Definitions of MIDI

Definitions of MIDI

Abbreviated as MIDI by ABBREVIATIONFINDER, Digital Interface for Musical Instruments. Physical communication standard between systems (connectors, cables, communication protocols) and the characteristics of the language that make the exchange of information between systems possible. MIDI does not transmit sounds, but information about how a certain piece of music is to be played. It would be the computer equivalent of the score. It is currently used in a wide variety of applications: music recording, film, TV, home computers, multimedia presentations]].


  1. A large amount of storage space is required to save the sampled audio (eg, as.WAV or AIFF files).
  2. About 10 Mb of disk space is required to store 1 minute of stereo audio sampled in CD quality (16 bit 44.1kHz).
  3. It offers the ability to edit the music with ease.
  4. Allows you to alter the playback speed and pitch of sounds independently.


The sudden inception of analog synthesizers in popular music in the 1970s led musicians to demand more performance from their instruments. Interconnecting analog synthesizers is relatively easy as they can be controlled via variable voltage oscillators.

The appearance of the digital synthesizer at the end of the same decade brought with it the problem of the incompatibility of the systems used by each manufacturing company. In this way, it was necessary to create a common language above the parameters that each brand was generating throughout the development of the different electronic instruments made available to professionals in the sector.

The MIDI standard was initially proposed in a document addressed to the Audio Engineering Society by Dave Smith, president of the Sequential Circuits company in] 1981. The first MIDI specification was published in August 1983. It should be noted that MIDI does not transmit audio signals, but event data and controller messages that can be interpreted arbitrarily, according to the programming of the receiving device. In other words, MIDI is a kind of score that contains the instructions in numerical values ​​(0-127) on when to generate each sound note and the characteristics it must have; the device to which the score is sent will transform it into fully audible music.

Today, the vast majority of music creators use the MIDI protocol in order to perform score editing and pre-recording instrumentation with real instruments. However, the perfection acquired by synthesizers today leads to the direct use in recordings of the sounds resulting from sending the electronic score to these latest generation synthesizers.


Educational use of music computing

The basic MIDI system is one that allows us to record sequences and reproduce them on synthesizers. For this we need a computer with programs that act as a sequencer, where we can record sequences (MIDI data) that are sent to the synthesizer (sound generator) connected to a sound amplification system.

Basic components

MIDI interface This is the device used to send and receive MIDI data from the computer. Many sound cards allow you to use special connectors for the joystick port, which allow your computer to communicate with electronic musical instruments. The most modern musical devices also allow connection through the RS-232 serial port that all computers carry with them from the factory, Cables and connectors: The connectors through which MIDI information circulates all have the same appearance: they are of the DIN type with 5 pins. MIDI cables have a male connector on each end. MIDI connectors can have three types of functions:

  • The MIDI IN connector is the port where data arrives]] from another device. The data that arrives through an IN connector to a synthesizer is transformed into music.
  • The MIDI OUT outputs the data that has been generated on the device itself. When you play on a MIDI keyboard you are sending information that is output from the OUT port.
  • Data is also output from the MIDI THRU connector but, unlike OUT, it is not produced on the same device, but is just a copy of what comes through MIDI IN. It is used to chain three or more MIDI devices in the same system.

MIDI Virtual Instruments

MIDI relies on a message system to encode musical information, which can be of two types: channel messages and system messages. The user does not need to know in depth the meaning of all the messages, since the devices and programs generate and interpret them automatically.

MIDI multitimbral synthesizers usually have 16 modules, each of which behaves as if it were a musician in an orchestra, playing the instructions sent to it with a specific instrument, as if it were reading a sheet music. Messages can be sent to the entire orchestra at the same time, or to just one of the synthesizer musicians (play a certain note, pick up a different instrument, play with more intensity …). Part number 10 tends to behave in a different way: he is the percussionist, and he interprets some orders in a different way than other musicians do.

Channel messages refer to a musical action on a certain instrument. There are 16 possible channels, this means that a synthesizer can act as an “orchestra” of 16 musicians, each of which receives individualized information about what it has to interpret.


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