Practically every electronic musician uses MIDI, but many have only a vague understanding of exactly what it is, what it isn’t, and how it works.
You probably know that MIDI allows data to flow between synths and software, but how well do you really know it? Do you regard it as some kind of digital magic that just works when you need it to (or not)? As the MIDI Specification approaches its 37th anniversary in January, the web remains rife with misinformation that perpetuates misconceptions about what MIDI can and can’t do.
The MIDI Association (MIDI.org) is a non-profit organization that encourages and supports the use of MIDI. Its purpose is to disseminate accurate, up-to-date information about MIDI and to promote communication and creativity among MIDI users and manufacturers. The MIDI Association’s membership comprises MIDI users from around the world. Anyone who uses MIDI is free to join at no cost.
Even though the basic rules of MIDI are essentially unchanged since the original ratification and publication of the MIDI Specification in 1983, it is a living document that continues to evolve. Its evolution takes place through the efforts of the MIDI Manufacturers Association, a consortium of companies that make MIDI products and ensure their continuing compatibility (aka interoperability) between devices, as well as their Japanese counterpart, the Association of Music Electronics Industry. These organizations meet every year to incorporate technological advances into the existing MIDI Spec by adopting extensions such as General MIDI, Standard MIDI Files, MIDI Polyphonic Expression, and most recently, MIDI Capability Inquiry, which will allow MIDI devices to communicate their capabilities to one another.
Extensions to MIDI have reached the point that continuing to call the specification MIDI 1.0 is no longer appropriate. Consequently, the MIDI Manufacturers Association is very close to ratifying MIDI 2.0, which will set the stage for even greater expansion of the MIDI standard. You’ll be reading more about MIDI 2.0 in Synth and Software in the near future.
This article is the first in a series we plan to post from MIDI.org, and it’s published with the kind permission of the MIDI Association.
— Geary Yelton
Top photo by composer Drew Neumann showing his personal studio, Droomusic
About MIDI – Part 1: Overview
MIDI (pronounced mid-e) is a technology that makes creating, playing, or just learning about music easier and more rewarding.
Playing a musical instrument can provide a lifetime of enjoyment and friendship. Whether your goal is to play in a band, or you just want to perform privately in your home, or you want to develop your skills as a music composer or arranger, MIDI can help.
How Does MIDI Work?
There are many different kinds of devices that use MIDI, from cell phones to digital music instruments to personal computers. The one thing all MIDI devices have in common is that they speak the “language” of MIDI. This language describes the process of playing music in much the same manner as sheet music: there are MIDI messages that describe what notes are to be played and for how long, as well as the tempo, which instruments are to be played, and at what relative volumes.
MIDI Is Not Audio
MIDI is not audio. So if someone says MIDI sounds bad, they really don’t understand how MIDI works. Imagine if you took sheet music of a work by Beethoven and handed it to someone who can read music, but has never played the violin. Then you put in their hands a very cheap violin. The music would probably sound bad. Now take that same piece of sheet music and hand it to the first chair of a symphony orchestra playing a Stradivarius and it will sound wonderful. So MIDI depends on the quality of playback device and also how well the description of the music fits that player.
MIDI Is Flexible
The fact that MIDI is a descriptive language provides tremendous flexibility. Because MIDI data is only performance instructions and not a digital version of a sound recording, it is actually possible to change the performance, whether that means changing just one note played incorrectly, or changing all of them to perform the song in an entirely new key or at a different tempo or on different instruments.
MIDI data can be transmitted between MIDI-compatible musical instruments or stored in a Standard MIDI File for later playback. In either case, the resulting performance will depend on how the receiving device interprets the performance instructions, just as it would in the case of a human performer reading sheet music. The ability to fix, change, add, remove, speed up, or slow down any part of a musical performance is exactly why MIDI is so valuable for creating, playing, and learning about music.
The Three Parts of MIDI
The original Musical Instrument Digital Interface (MIDI) specification defined a physical connector and message format for connecting devices and controlling them in real time. A few years later, Standard MIDI Files were developed as a storage format, so performance information could be recalled at a later date. The three parts of MIDI are often just referred to as MIDI, even though they are distinctly different parts with different characteristics.
1. The MIDI Messages – the Software Protocol
The MIDI Messages specification (or “MIDI Protocol”) is the most important part of MIDI. The protocol is made up of the MIDI messages that describe the music. There are note messages that tell the MIDI devices what note to play, there are velocity messages that tell the MIDI device how loud to play the note, there are messages to define how bright, long, or short a note will be. There are Program Change messages that tell the MIDI device what instrument to play. So by studying and understanding MIDI messages, you can learn how to completely describe a piece of music digitally.
2. The Physical Transports for MIDI
Though originally intended just for use with the MIDI DIN transport as a means to connect two keyboards, MIDI messages are now used inside computers and cell phones to generate music, and transported over any number of professional and consumer interfaces (USB, Bluetooth, FireWire, etc.) to a wide variety of MIDI-equipped devices.
There are many different cables & connectors that are used to transport MIDI data between devices.
MIDI Is Not Slow
The MIDI DIN transport causes some confusion because it has specific characteristics that some people associate as characteristics of MIDI, forgetting that the MIDI-DIN characteristics go away when using MIDI over other transports (and inside a computer). With computers, a high-speed serial, USB, or FireWire connection is more common. USB MIDI is significantly faster than 5-pin DIN. Each transport has its own performance characteristics that might make some difference in specific applications, but in general, the transport is the least important part of MIDI, as long as it allows you to connect all the devices you want use.
3. The File Formats for MIDI Files
The final part of MIDI is made up of the Standard MIDI Files (and variants), which are used to distribute music playable on MIDI players of both the hardware and software variety. All popular computer platforms can play MIDI files (*.mid), and there are thousands of websites offering files for sale or even for free. Anyone can make a MIDI file using commercial (or free) software that is readily available, and many people do. Whether or not you like a specific MIDI file can depend on how well it was created and how accurately your synthesizer plays the file. Not all synthesizers are the same, and unless yours is similar to that of the file composer, what you hear may not be at all what he or she intended.
Even More MIDI
Many people today see MIDI as a way to accomplish something, rather than as a protocol, cable, or file format. For example, many musicians will say they “use MIDI,” “compose in MIDI,” or “create MIDI parts,” which means they are sequencing MIDI events for playback via a synthesizer, rather than recording the audio that the synthesizer creates.