What is MIDI? Our Ultimate Guide To Music Software's Most Powerful Tool

The whole subject of what is MIDI can be very confusing when you are setting up your first home recording studio. This article aims to turn you into a MIDI Ninja.

Your MIDI FAQs Answered

What is MIDI – a Video Tutorial Introduction
1. What IS MIDI vs Audio recording? What is the difference?
- MIDI vs Audio Explained – Video Tutorial
2. MIDI – A brief definition
3. What does MIDI actually do?
4. What are MIDI notes, events and channels? And what is MIDI thru?
- MIDI Thru
5. What is a MIDI Sequencer?
6. My MIDI keyboard doesn’t make a sound … so how does it work?
7. How can I connect my digital piano to my computer and use it as a MIDI controller?
8. Your MIDI keyboard is connected, now what can you do with it?
9. What is a MIDI file?
10. You play a guitar so can you use MIDI? What other instruments can you use?
11. Your MIDI keyboard doesn’t seem wor how can you test it?
MIDI Magic …
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More Common MIDI Questions Answered
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Questions sound familiar? Hopefully we can answer all these questions for you. And get to the bottom of just what is MIDI. So you can get on with playing, recording and making the most of your home recording studio. But let’s start with a video …

What is MIDI – a Video Tutorial Introduction

What is MIDI? A Basic introduction: Connect Keyboard Lesson 12 — What is MIDI? Video Explainer

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1. What IS MIDI vs Audio recording? What is the difference?

This is the BIG question. The number one confusing thing about MIDI. Once you understand the difference between MIDI and Audio, everything else begins to make sense. And the easiest way to answer this question is actually to show you.

MIDI vs Audio Explained – Video Tutorial

MIDI vs AUDIO: Connect And Record Your Keyboard Lesson 1 — MIDI vs Audio Video Explainer

In short, MIDI does NOT transmit an actual audio signal. It is not the sound of anything. MIDI is just a string of data. It’s a set of instructions that machines use to speak with eachother. And as you saw in the above video, this means you can manipulate the data in all kinds of ways.

2. MIDI – A brief definition

MIDI stands for Musical Instrument Digital Interface. It is an industry-standard protocol for swapping information between suitably equipped electronic musical instruments and computers. It is very important to realise that the information being transmitted is control or performance information, NOT the actual sound itself. However, as you saw above, the transmitting and recording of this control information makes all sorts of things possible.

MIDI was first developed in the early 80s to standardise communication between music hardware. The reason it has survived so long is because it was adopted by every major manufacturer. They worked together to create, modify and perfect MIDI. So MIDI has been around a long time. It has its limitations due to how long it has been going. But, it is a universal language.

3. What does MIDI actually do?

Let’s assume you have a MIDI keyboard controller. As you play, all the information gets transmitted as a series of messages. This stream of data can be used in a number of ways. Here are just a very few examples.

record an entire sequence in a DAW (as shown in the video above) which can then be edited and tidied up
use one controller to play another MIDI-enabled instrument, or any virtual instrument. The controller does not necessarily have to be a keyboard. There are many control surfaces, breath controllers, you can even get your guitar to transmit MIDI information.
program drum tracks, or set up drum machines
MIDI can even be used to control other devices, for example effects boxes. This makes real time control of effects possible. You can also control lighting at live events and co-ordinate music with graphics.

4. What are MIDI notes, events and channels? And what is MIDI thru?

The MIDI protocol lets a device send messages over one to sixteen different channels. This allows you to have 16 parts with different voices going on all at once. And all the data is streamed down one cable. The most basic MIDI message is the Note-On. This message includes the channel, the note pressed (where middle C is number 60 etc), the velocity (ie how hard the key has been pressed) and a timestamp. The corresponding note-off message will turn that same note off, according to when you release the key.

Other channel messages include aftertouch, and control change messages such as pitch bend, and program change, sustain pedal and expression.

What you are seeing in the piano roll view in a sequencer is a graphical representation of all these messages. The graphical view makes it easy for you to edit all the data after. So you can correct mistakes (like wrong notes).

So all these messages are the heart of what MIDI is. And every MIDI-enable instrument understands these messages, because they are standardised. It’s actually a beautifully simple system.

MIDI Thru

MIDI THRU duplicates the data coming to the MIDI IN port. This allows you to connect multiple devices without needing multiple ports on your sequencer or MIDI interface.
MIDI THRU allows you to connect all your gear together with one central sequencer. This is called “Daisy Chaining.”

5. What is a MIDI Sequencer?

Back in the day, MIDI programs were just that, MIDI only. So a MIDI sequencer was software that allowed you to record, edit and playback most types of messages. Especially channel voice messages around note events.

In addition to the traditional graphical MIDI sequencers, notation software is also something that has been enabled by MIDI. All the MIDI note-on and note-off messages can be displayed as a traditional score.

Nowadays, you generally expect software to be able to combine MIDI sequences with Audio. So this is the full-featured Digital Audio Workstation (or DAW). And most DAWs also have a notation view as well. Through your DAW you have access to numerous ‘virtual instruments’. These are software instruments and samples that can be ‘played’ via your MIDI information. So from a humble computer you can make absolutely any sound, and “play” any instrument you want!

6. My MIDI keyboard doesn’t make a sound … so how does it work?

Hopefully you have almost got the idea of this by now. The MIDI keyboard is literally a controller. It doesn’t need to make a sound, because MIDI data is not the same as audio. There is no sound being transmitted anywhere. Just a series of events. So the traditional MIDI keyboard is literally a dummy keyboard. You play the notes, twiddle the knobs, slide the faders, and so on. All the DATA is transmitted and you can either record it in sequences (in your DAW), or display it as notation (in your score writing software) or play live instruments. The instruments are more often than not going to be “virtual instruments” available through your software. OR, you may have a hardware synth. The process is the same.

The principle of being able to play virtual instruments is governed by another industry-standard protocol. That of the VST (or Virtual Studio Technology). This is what makes MIDI so cool. And so flexible.

7. How can I connect my digital piano to my computer and use it as a MIDI controller?

Because MIDI is such a standard thing, nearly every digital piano and electronic music keyboard will have MIDI capability. This is useful if you want to buy, for example, a digital piano. And you don’t have the room for an additional controller. Many keyboards and pianos will have ‘USB to Host’. This means all you need is a standard USB lead to connect your keyboard up to your computer. Many will also work with iPad as well. You will probably need the camera connector to do this.

Every keyboard is slightly different, but there will be a section in the manual to explain how to connect your keyboard. Or, read this post, where the process of making a MIDI connection is explained in more detail.

Some keyboards do not have USB, but instead have standard MIDI ports. All you need in this instance is a MIDI-USB interface and you can achieve the same thing.

8. Your MIDI keyboard is connected, now what can you do with it?

Once your keyboard is connected, you can do loads of things. Firstly you can use it to play an instrument other than the one you are playing. For example, software instruments on your computer. Secondly, you can ‘record’ your performance and then perfect it. Or even speed it up, or slow it down, a little. Thirdly you can easily transpose your recording. So you can play in an easy key and then adjust at the press of a button.

You can play one hand at a time, and put the two tracks together. If you play by ear, you can play to your heart’s content, and then share your playing as a notate score with other people. even if you can’t read music very well (if at all).

And there is so much clever software that can do all kinds of things for you. As an example, take Band In A Box, which can interpret the chords from your playing, and generate accompaniments.

Finally, you can create as many tracks as you like, and gradually build up a complete song. Record all the tracks then sing along on top. Refer to our post on music making software for examples of easy-to-use software that will enable you to do just that.

These are just a few examples … once you have a MIDI controller (or your keyboard) connected then there are no limits to your musical possibilities.

9. What is a MIDI file?

A MIDI file is literally a file containing lots of MIDI information. It will be called [something].MID and again it is an industry standard thing. So once you have a MIDI file you can import it into most MIDI software. Whether you want to create a score, or use it as the basis of an arrangement. MIDI files are very small, too, so easily passed around. However, do be aware that they only contain MIDI information. Your DAW will have its own file format for storing all the rest of the information in your sequences, and MIDI will only be one small part of this.

10. You play a guitar so can you use MIDI? What other instruments can you use?

Yes! Although a keyboard is the instrument traditionally associated with MIDI, you can use your guitar as a controller, if you own the right kit. We explain a bit more about guitars and MIDI in a different post. Furthermore, if you are a wind player (clarinet or sax) then you can buy a MIDI breath controller. And finally there are a whole host of control surfaces from companies like Native Instruments and AKAI. So there are multiple ways that you can be a MIDI genius, keyboard or no keyboard.

11. Your MIDI keyboard doesn’t seem wor how can you test it?

Most good manufacturers have excellent support pages, and helpful advice. But sometimes you need a bit more help. We have a post on how to test your MIDI device which you might find helpful. This will work for all MIDI hardware, not just keyboards.

MIDI Magic …

Of course MIDI isn’t perfect. In the search for a general standard, compromises have had to be made. And because it was first proposed back in the early 1980’s, the protocol had to be limited by the processing power available at the time. If it were to be developed now, MIDI would be bigger and better. More channels and so on. BUT it has survived for well over 30 years because it is a standard across all manufacturers.

And this is the great thing about MIDI. It is a universal protocol which is brand independent. The benefits of being able to link all kinds of different equipment together, and share the results in MIDI files which will play back on any MIDI device cannot be underestimated. The amazing range of educational packages now available is a direct result of the MIDI protocol, and the far-sighted group of manufacturers who developed it way way back in time.