MIDI

MIDI, Musical Instrument Digital Interface, is an industry-standard protocol that enables electronic musical instruments, computers, and other equipment to communicate, control, and synchronize with each other. Files in this format usually have a .MID extension.

[edit] Overview

MIDI is different from other audio formats in that it does not represent sounds as they would be recorded. Instead it represents the notation of music in a data format. Basically it could be thought of as an electronic musical score. It has a sequence of notes and duration of each note and other information needed to reproduce the notes. It also identifies the instrument so a program can be used to generate the sounds from the notation information. Multiple simultaneous notations are in the file format so an entire orchestra can be reproduced. The file format is much smaller than would be required to record the sound.

The data includes such items as the pitch and intensity of musical notes to play, control signals for parameters such as volume, vibrato and panning, cues, and clock signals to set the tempo. A composer could code the data directly and then listen to the music it would produce. This is a common use for this format and it is used often to drive a keyboard or other midi compatible instrument although it can also be used directly by a computer that has a program that can interpret this data.

Note that this music format differs from other music formats discussed in the article on sound in that they represent the recording of a particular performance while the midi format is an idealized representation of the music which can then be rendered by a music machine. MIDI format provides the ability to easily edit the individual components of a piece of music.

[edit] File formats

There are several file formats used to represent MIDI data. One format using the .KAR extension is specific for Karaoke machines and includes synchronized text for the words.

The SMF, standard MIDI format, specification was developed by, and is maintained by, the MIDI Manufacturers Association (MMA). MIDI files are typically created using computer-based sequencing software (or sometimes a hardware-based MIDI instrument or workstation) that organizes MIDI messages into one or more parallel "tracks" for independent recording and editing. In most sequencers, each track is assigned to a specific MIDI channel and/or a specific General MIDI instrument patch. Although most current MIDI sequencer software uses proprietary "session file" formats rather than SMF, almost all sequencers provide export or "Save As..." support for the SMF format.

Microsoft Windows uses a RIFF-based MIDI files with the .rmi extension. Note, Standard MIDI Files per se are not RIFF-compliant. A RIFF-RMID file, however, is simply a Standard MIDI File wrapped in a RIFF chunk. If you extract the data part of the RIFF-RMID chunk the result will be a regular Standard MIDI File.

XMF (eXtensible Music File) is a new file format approved for MIDI use. Some forms package SMF chunks with instrument data in DLS format (Downloadable Sounds, also an MMA/AMEI specification), to much the same effect as the MOD file format. The XMF container is a binary format.

[edit] MIDI 2.0

In 2020 MIDI 2.0 was released. The following data was taken from the MIDI web site:

[edit] MIDI 2.0 Means Two-way MIDI Conversations

MIDI 1.0 messages went in one direction: from a transmitter to a receiver. MIDI 2.0 is bi-directional and changes MIDI from a monologue to a dialog. For example, with the new MIDI-CI (Capability Inquiry) messages, MIDI 2.0 devices can talk to each other, and auto-configure themselves to work together. They can also exchange information on functionality, which is key to backward compatibility—MIDI 2.0 gear can find out if a device doesn't support MIDI 2.0, and then simply communicate using MIDI 1.0.

[edit] Higher Resolution, More Controllers and Better Timing

To deliver an unprecedented level of nuanced musical and artistic expressiveness, MIDI 2.0 re-imagines the role of performance controllers, the aspect of MIDI that translates human performance gestures to data computers can understand. Controllers are now easier to use, and there are more of them: over 32,000 controllers, including controls for individual notes. Enhanced, 32-bit resolution gives controls a smooth, continuous, "analog" feel. New Note-On options were added for articulation control and precise note pitch. In addition, dynamic response (velocity) has been upgraded. What's more, major timing improvements in MIDI 2.0 can apply to MIDI 1.0 devices—in fact, some MIDI 1.0 gear can even "retrofit" certain MIDI 2.0 features.

[edit] Profile Configuration

MIDI gear can now have Profiles that can dynamically configure a device for a particular use case. If a control surface queries a device with a "mixer" Profile, then the controls will map to faders, panpots, and other mixer parameters. But with a "drawbar organ" Profile, that same control surface can map its controls automatically to virtual drawbars and other keyboard parameters—or map to dimmers if the profile is a lighting controller. This saves setup time, improves workflow, and eliminates tedious manual programming.

[edit] Property Exchange

While Profiles set up an entire device, Property Exchange messages provide specific, detailed information sharing. These messages can discover, retrieve, and set many properties like preset names, individual parameter settings, and unique functionalities—basically, everything a MIDI 2.0 device needs to know about another MIDI 2.0 device. For example, your recording software could display everything you need to know about a synthesizer onscreen, effectively bringing hardware synths up to the same level of recallability as their software counterparts.

[edit] Built for the Future

MIDI 2.0 is the result of a global, decade-long development effort. Unlike MIDI 1.0, which was initially tied to a specific hardware implementation, a new Universal MIDI Packet format makes it easy to implement MIDI 2.0 on any digital transport (like USB or Ethernet). To enable future applications that we can't envision today, there's ample space reserved for brand-new MIDI messages.

Further development of the MIDI specification, as well as safeguards to ensure future compatibility and growth, will continue to be managed by the MIDI Manufacturers Association working in close cooperation with the Association of Musical Electronics Industry (AMEI), the Japanese trade association that oversees the MIDI specification in Japan.

MIDI will continue to serve musicians, DJs, producers, educators, artists, and hobbyists—anyone who creates, performs, learns, and shares music and artistic works—in the decades to come.