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What is MIDI, how it works, and how to use it?

MIDI is a method of sending data that allows you to create music digitally. It doesn’t matter if you are a bedroom producer or a Grammy Award winner; MIDI will play a big part in your working life.

In this article, I will go into more detail about what MIDI is, how it works, and how to use it.

If you are a complete newbie, don’t worry, it’s not as complicated as it might sound. I will walk you through it step by step, putting everything in simple terms; let’s get started.

What is MIDI?

MIDI stands for Musical Instrument Digital Interface, and it’s one of the most powerful tools in music production.

MIDI plays a huge role in every step, from recording to mixing, and if you make music of any kind, you most likely use MIDI.

The easiest way to think of MIDI is that it’s a digital language. It’s the language that allows musical instruments, computers, and other compatible hardware to communicate.

In the 1980s, there was a massive increase in the number of digital instruments and digital music gear available. This new wave of digital technology brought with it limitless creative potential.

However, there was a problem; each manufacturer had its own way of doing things. That meant that equipment from one manufacturer wouldn’t be compatible with equipment from another.

It meant the idea of picking the best gear from different manufacturers to create your ideal setup just wasn’t possible for music makers.

MIDI was the solution that made gear from different manufacturers compatible with each other.

A brief history of MIDI

MIDI is a surprisingly deep topic if you want to go back far enough. According to the MIDI Association, you have to go all the way back to 850 AD and the very first mechanical instruments to understand the origins of MIDI.

You’ll be glad to hear that we won’t be going so far back. We only need to go as far back as the early 1980s when some of the pioneers of digital instruments got together to create a standard protocol that would eventually become MIDI.

Ikutaro Kakehashi and Don Lewis
MIDI pioneers Ikutaro Kakehashi and Don Lewis

Ikutaro Kakehashi might not be a household name, but if you are into digital music production, he should be. He is the founder of Roland, a company that has manufactured some of the most iconic, era-defining synthesizers and drum machines.

He was the one who kickstarted the idea of a standard protocol and presented the concept to other leading manufacturers, most notably, Sequential Circuits.

Developing a standard protocol or language that could accurately communicate complex aspects of a musical performance to a computer or other hardware was a daunting task.

Dave Smith of Sequential
Dave Smith of Sequential

In 1982, MIDI was unleashed, and it has shaped the future of digital music ever since. In 2013, Ikutaro Kakehashi and Dave Smith (founder of Sequential Circuits) were honored with Technical Grammy Awards for their efforts in developing MIDI.

How MIDI works?

MIDI sends digital data in the form of MIDI messages that trigger a specific behavior from your computer or hardware. In other words, it tells them exactly what to do; the keyword here is data.

If you remember the word data, you will remember that MIDI never ever sends audio; only data messages.

Let’s take the most basic MIDI set up; a laptop and a MIDI controller keyboard. Imagine you are using a virtual piano instrument, something like Keyscape.

When you are playing, it will feel the same as playing any other keyboard instrument. You press a key, and you hear the corresponding note/pitch. If you press the key harder, the note is played louder, and so on.

The first thing to remember here is that the sound isn’t coming from the MIDI keyboard; it’s coming from the virtual instrument on your computer.

What’s happening in behind the scenes is that the controller keyboard is sending MIDI messages to the computer and software telling it how to behave.

Types of MIDI messages

There are two types of MIDI messages: channel messages and system messages.

Channel messages are the more common of the two types: they deal with performance aspects. System messages deal with the more technical functions like your transport controls.

MIDI channel messages contain information about multiple performance aspects, not just which note to play. The messages also detail things like velocity and how long the note should be held or note on/off to be more precise.

We know that computers deal in numerical values, so that’s the easiest way to explain it.

Imagine each note on the keyboard is numbered from 1 to 88. Pressing any note provides the computer with a number that triggers the correct sound from the virtual instrument.

Now imagine velocity has a value range between 1 and 10, with 10 being the loudest. By pressing a key, you generate a velocity value that the computer and software can understand and use to produce the correct velocity.

This system is how MIDI accurately reproduces dynamic musical performances. The quality largely depends on the virtual instrument (VST plugin) being used.

For example, piano software that sampled 100 velocity layers will be far more expressive than one that only sampled 10 velocity layers.

The most common MIDI channel messages are:

  • Note on/off – determines which note is pressed, how long it’s held and contains velocity data.
  • Pitch bend – determines any change in pitch due to moving the pitch bend wheel/stick.
  • Aftertouch – determines pressure applied to a key after the initial press. Not all MIDI controllers have aftertouch. Where applicable, aftertouch can be designated to trigger different effects.
  • Control changes – A control change can be any parameter change on your MIDI controller. It could be a slider/fader, knob, or button.
  • Program changes – determines the selected patch/sound.

MIDI system messages are less frequent, but here are the most common ones:

  • Transport controls – these controls work with your devices or DAW, telling them when to start, stop, record, etc.
  • Clock – syncs your device with the master clock, commonly your DAW.
  • Sysex – system exclusive messages are specified by the manufacturer of the device.

MIDI events

MIDI events are like recordings of MIDI messages in your sequencer or DAW.

Since MIDI never deals with audio, to record music, it creates MIDI events that are triggered when the playhead passes them. It’s basically capturing your performance through a sequence of digital messages.

MIDI channels

A single MIDI stream can control up to 16 channels at once.

The best way to think of MIDI channels is to compare them to tracks in your DAW. If you were recording multiples instruments at once, you’d assign each instrument to an individual track.

If you want to control more than one MIDI device at the same time, you assign each device to a MIDI channel so that they can play different sounds.

You could have one controller sending the same MIDI data to every device, or you could have multiple devices sending MIDI data.

For example, you could have two MIDI keyboards, one set to send on MIDI Channel 1, the other sending on MIDI Channel 2.

You could then set some gear to receive on Channel 1 and some on Channel 2. Now you’ve got different instrumentation for different keyboard parts, which is an incredible tool for live performance.

MIDI cables

MIDI cables look unlike other cables that you’ll be used to using. These cables are called five-pin DIN cables, and they are the MIDI standard.

Many modern synthesizers and most interfaces offer a USB connection, which is far easier for a typical DAW setup.

MIDI inputs and outputs

MIDI-compatible gear can have up to three MIDI ports, which are MIDI In, MIDI Out, and MIDI Thru.

MIDI inputs, outputs, and cable
MIDI In, Out, Thru, and MIDI cable

The five-pin MIDI ports aren’t as scary as they might seem if you are just used to dealing with USB or 1/4-inch TRS/jack.

Like any other signal path in music, the output of the device that you want to send MIDI data should be routed to the input of the device that you wish to receive it.

MIDI Thru can be a little more confusing, but in simple terms, it lets you send the same MIDI data to more than one device.

If you route the MIDI Thru of the first device to the next device and the next, you can daisy-chain them; controlling all with the same MIDI stream.

Remember to set each device to a different MIDI channel.

How to use MIDI?

Before we get into what you can do with MIDI, let’s look at the most common MIDI setups.

DAW + MIDI controller

The most common is a DAW and a MIDI controller. This kind of setup is common because it’s so simple. All you need is a USB cable between your computer and your MIDI controller.

One of the major benefits of working this way is that it’s so portable. It’s just as good on the road as it is in your home studio.

Despite being portable and streamlined, a setup like this can be incredibly powerful with the help of virtual instruments. A compact 25-key MIDI keyboard can become a whole band or even an entire orchestra.

Computer + MIDI interface + synthesizer

Another common setup is a computer, a MIDI interface, and an external hardware synth. The main reason to set up this way is to take advantage of the convenience offered by your DAW without losing the performance quality that hardware provides.

It allows you to input, edit, and sequence inside your DAW efficiently before sending MIDI data to the hardware via the interface for playback.

If you want to go 100% hardware and cut the computer out completely, that’s no problem. In this scenario, you would use a hardware sequencer in place of your DAW.

Many synths have built-in sequencers, or you could go for something like an Akai MPC. Then you’d use MIDI Thru as described above to pass the MIDI stream to each device.

Why use MIDI?

Without a doubt, the most significant benefit of MIDI is editing power.

When you record audio, and something isn’t quite right, you probably have to record another take. Some tools allow you to edit audio to prevent the need for another take, but it’s never as convincing as just doing it again.

With MIDI, you don’t have that problem at all.

Once you record MIDI into your DAW, you can edit and manipulate every aspect of your performance at the touch of a button. We can use Logic, one of the best DAWs available, as an example.

piano roll and MIDI events in Logic DAW
Piano Roll and MIDI events in Logic Pro | Image: Apple

Opening the piano roll in Logic will show your MIDI events (notes) as colored blocks. Each block’s color relates to the velocity of the note, and a vertical keyboard shows the pitch down the left side.

If a note is a semitone out, you can simply click and drag it to the correct pitch. All other data, like velocity, sustain, and length will remain the same. Likewise, if a note just shouldn’t be there you can delete it without affecting the rest of the performance.

You can quantize your performance to make sure it’s perfectly in time. Or, you can quantize it to feel like it’s pushing or pulling.

It makes it easy to record a sequence in layers, too. For example, if you are recording virtual drums using a keyboard, you could record on a four-bar loop: kick first, then snare, and so on.

That way, you can create parts that are far too complex to play in one go then quantize it, so all the individual elements fit together.

One of the most significant advantages of editing MIDI is the speed at which you can create entire tracks. It’s not unusual for multiple instruments to play the same part, like bass, synth, and piano, all playing the same line. Rather than play it three times, play it once and copy/paste the MIDI events onto the other tracks.

Now that you’ve got the foundation for your track, you can start to try different ideas, like playing in octaves, or placing the synth line a perfect fifth above the bass, etc.

Even if you don’t have access to a controller, you can create music this way anywhere with just a laptop by drawing in each note with your mouse.

Final thoughts

MIDI is one of the most important developments in modern music production, and we owe that to some true legends of the industry.

Some people will always say that MIDI and virtual instruments will never match the real thing, which might be true. The reality is that it depends on what genre you are working in, and virtual instruments are getting better by the day.

Whether you use MIDI to create radio-ready tracks or working demos, it will enhance your workflow no end. So get to know what MIDI can do in your setup and start getting the most out of it.