If you’re diving into the world of computer music, it won’t take long before you hear the acronym “midi” pop up. Midi means Musical Instrument Digital Interface, it’s the way your keyboard and computer talk to each other.
So when you press a note on your physical keyboard – I’m talking about a musical keyboard, not a computer keyboard here – your computer understands what note is being played.
You can send other types of Midi data to your computer too, like when you use a sustain pedal or turn the pitch or modulation wheels on your keyboard.
All this is recorded in midi format.
MIDI was invented in 1983 with the first MIDI enabled keyboards being the Prophet 600 and Roland Jupiter-6. Forty years later MIDI is still the foundation for all computer music that incorporates hardware keyboards and other midi controllers.
What Does Midi Data Look Like?
Let’s take a look at an actual midi note that’s been recorded into your computer’s music software (like GarageBand, Logic, Ableton or Cubasis).
Here’s a single note (C#) recorded as a MIDI file
You can adjust the pitch and length of the note depending where it sits in the editor.
The MIDI editor is sometimes called a piano roll, you’ll see the mini piano keys going vertically. The length of the notes determine how long the note is played. The higher the note is on the midi editor screen, the higher pitched it will sound.
You are able to capture a lot of MIDI data at once, not just note presses. More on that later.
What Is A Midi Controller?
A MIDI controller is any device that is able to communicate with a computer by transmitting the physical note and button presses into a way that your computer understands.
Here are some examples of midi controllers:
- MIDI Keyboards
- Digital Pianos with MIDI output
- Pad style MIDI controllers
- Faders and Knob MIDI controllers
- Foot pedals (sustain/expression)
You can actually have all of these midi controllers plugged in and setup with your DAW (Digital Audio Workstation – GarageBand/Ableton/Logic) and recording midi notes all at once.
For example, you might be playing your midi keyboard (top left above), using the sustain pedal (top right above) and adjusting a filter (bottom left above). The pad midi controller is usually used to play notes instead of a midi keyboard – some people just prefer it, but you don’t often see a midi keyboard and pad controller played at once. It would be a bit redundant.
What Does A Midi File Look Like?
You’ve seen a super basic midi file earlier, but lets checkout something a bit more substantial so you can get a feel of the power of MIDI.
One of the awesome things about MIDI is that it’s a self contained file full of data. You don’t need to import MIDI data for the melody, then import MIDI data for the drums and then import MIDI data for the baseline. The single MIDI file contains all of it and it’s split up into its relevant sections when it’s imported into a DAW (digital audio workstation) like GarageBand, Logic Pro or Ableton.
Here’s what actual MIDI data looks like in the editor or piano roll:
There’s a ton going on in this MIDI file! You’ll see all sorts of midi notes being played – both the melody, bass and drums. Oh yeah, I forgot to mention, MIDI can also control drum samples, it’s not just for melodies or bass lines.
How Do You Play Drums With MIDI?
You might be wondering how drums are programmed and played via MIDI. Usually this is done by assigning audio samples of the drums (like a kick drum or a hi-hat) to specific notes on the keyboard. You can then press the note on the physical musical keyboard and the drum sound will play.
The MIDI editor will look exactly the same as if you were programming a keyboard lead sound for example, except instead of playing a note (like a piano note), you’ll hear the drum sound played once.
Here’s an example. I’ve loaded up the quick sampler plugin in Logic Pro and added a kick drum.
The sampler has automatically associated the kick drum audio with the different keys on your musical keyboard. The lower the notes I play on the keyboard, the lower the kick drum audio sample will be played. Similarly, the higher I play the notes on the music keyboard, the higher the kick drum audio will be.
Now, there are a few other ways of playing drums via midi. Depending upon which DAW (Digital Audio Workstation) you choose, like Logic Pro or Ableton, they might have an alternative way of allowing you to play drums via midi that’s even easier than loading up an instance of Quick Sampler and adding the drum sounds one by one.
Logic has an instrument called “Drum Machine Designer”. Here you’ll be able to select the sample for each part of your drum kit and then program the notes via Midi. So for instance, you’d load up drum machine designer..
In each space you would select an audio drum sample, for example a kick drum, a clap sample and a closed hi-hat sample. Then when you’ve chosen your drum samples, you can open the editor view and program when the drums should play, just like above with the piano notes.
And here’s how the actual midi data looks for the kick drum and hi-hats. I left out the clap because it was on top of the hi-hats midi.
Just to throw something else at you – you can just copy the drum audio file its self and import that into your DAW like GarageBand/Logic/Ableton then copy and paste the audio file where you need it to be. So the kick drum for hip-hop/dance music usually falls on beats 1,2,3 or 4, you’d copy and paste this to the correct timing.
This would bring the same result as using the sampler and midi controls, but one huge advantage that MIDI controlled drums have over manually adding in the samples is that if you want to change the drum sound – let’s say the kick drum isn’t really doing it for your song, you can just switch the sample that’s loaded into the Quick Sampler and you’re done.
If you manually added the kick drum audio file where it needs to be in the DAW sequencer, you’d have to go in and change every single drum sound one by one. This can be a huge time consumer.
What Other MIDI Data Can I Record?
In addition to being able to record the musical keyboard notes you press, you can record other data from your musical keyboard and have your DAW play it back, just the way you played it.
The second most common data that MIDI records is velocity. Velocity is how hard or soft a note is played, or the volume or the note. Many MIDI keyboards come with velocity sensitive notes, so just like a real piano, the harder the key is hit, the louder it is.
Not that this is really important if you’re just starting out, but MIDI velocity is measured between 1-127. That means there are 127 different levels of velocity each note can hold, or in other words there are 127 volume levels that can be assigned to the note. From the very most quietest, to full on LOUD.
You can alter the MIDI velocity on the editor/piano roll after you’ve recorded the notes from your MIDI keyboard. It looks like this:
Just to add something more to velocity, some MIDI keyboards have “aftertouch”. This means that not only when you initially press a note on your MIDI keyboard the hardness/softness (velocity) of the note is recorded, but you can press harder of softer after you’ve already pressed the note and the sound will change. This is handy if you’re recording orchestral instruments, virtual guitars and some software synth plugins like Pigments and Phase Plant. You might get a faster filter modulation, or you might get a volume increase (yep there’s more than one way to record volume information). Aftertouch isn’t really standard on MIDI keyboards, but gradually more and more are being shipped with it. Aftertouch isn’t really essential to your MIDI keyboard, but once you get the hang of things you can really add extra feeling to what you’re playing.
Many MIDI keyboards come with a pitch bend and modulation wheel. This data can also be recorded as MIDI data and you can edit it on the editor screen in your DAW. A pitch bend wheel changes the tone of the audio higher or lower – usually by one full note. A modulation wheel can add everything from subtle wobbles to filtered madness to your sounds. If you get into audio plugins like soft synths, you’ll find many of the patches (sounds) included in the synth plugins to have customized modulation wheels that can do one or more things automatically as you move the wheel.
Earlier, I mentioned about the other devices that can record MIDI to your computer. A popular one is sustain.
A sustain pedal keeps the note held down, just as though your finger never left the musical keyboard key.
When pianos were invented, the sustain pedal made sure the hammers on the strings don’t dampen the sound (to zero), just as if they would do when your finger lifts off the key. Modern keyboards and digital pianos don’t have strings (some have hammers still), so sustain is recreated and implemented digitally.
When is a sustain pedal useful? If you’re playing a melody piece or string orchestra pads, you typically will see sustain used. It draws out the notes so that they blend in with the next ones harmoniously.
When you connect your sustain pedal to your music keyboard and record the MIDI, the computer sees the sustain pedal either ON of OFF. There’s no in-between, like the 127 step velocity. You’re either sustaining the notes or it’s not.
Sustain pedals are quite cheap really, there’s not much to them. You can even get a piano style sustain pedal with brass levers and everything. On the other hand, you can get a simple sustain pedal that’s just a switch.
To go even further with MIDI, you can record using an expression pedal.
Here’s what an expression pedal looks like:
An expression pedal can be assigned to a bunch of things – from filter cutoffs, volume, controlling fancy LFO’s in synths (makes the sound do crazy things). Expression pedals do use the full 127 levels of MIDI control to allow you to make small adjustments or large adjustments as needed.
A good example where an expression pedal might come in handy is recording orchestra scores. The strings section has many times where it becomes very quiet and delicate, but if your hands are playing the orchestra instruments, you don’t have any hands left to control the volume as you play.
Sure, you can adjust the volume (velocity) afterwards, but that would mean you going into the editor and adjusting each single note one by one. Nah!
Use your foot on the expression pedal as you play and bring the volume up and down as naturally as possible to recreate an orchestra strings section.
You can assign a lot of controls to the expression pedal – not just volume.
The last most common MIDI data that’s recorded is from knobs/faders/buttons.
This kind of MIDI controller lends itself nicely to synth style instruments as they usually have a ton of adjustable knobs and faders. A lot of MIDI keyboards have knobs and faders built in, but if you’re using a digital piano or a more portable type of midi keyboard, a separate knob/fader controller could come in handy.
Take a look at virtual synth Spire and the amount of knobs you can play with!
You’ll have to manually assign the knobs and faders of the synth to the knobs and faders of your hardware knob/fader box, but once you’ve done that you’ll be all set to tweak your sounds into something brand new.
So there’s a fast tour of what MIDI is and how it is the basis of computer music. Midi works the same way in Windows PCs and Mac laptops, there aren’t any differences in terms of how your DAW will record it. What I have noticed, though, is that Mac laptops tend to have less issues with drivers and latency. You can typically just plug the keyboard into the Mac and your setup ready to go.
With all the choices of MIDI controllers, you have to look at the type of music you want to make. Do you want to play live or create a song with drums, bass, lead melodies and so on? The best combination might be to get a MIDI keyboard controller that has built in knobs and faders, then buy a sustain pedal (under $20).
MIDI has been around for decades and the basic premise of how it works hasn’t changed. It’s a solid system that works and allows for easy editing and can be as simple or complex as you make it.