Sequencing is the process of “programming note and velocity information to control an electronic instrument.”

A sequencer handles MIDI (musical instrument digital interface) data. MIDI allows electronic musical instruments to communicate with each other; DAWs send MIDI messages to control synths and the notes you input on the piano roll will be stored as MIDI messages.

Input Methods

There are two ways of inputting MIDI data into your sequencer; in real-time and in non real-time.

A real-time input can be achieved using a MIDI controller keyboard. The MIDI data is inputted onto the piano roll in your DAW as you are playing the keys on the keyboard.

A non real-time input involves manually inputting, or ‘drawing’, all of the MIDI data into your piano roll.

Quantise

Quantise is “the rounding of data. Commonly used to fix the timing of rhythms.”

It is likely that when working with MIDI, there will be some inaccuracies in rhythm from the performer. This can either be fixed manually whereby you go through every note on the piano roll that is out of place and move it to where it should be. The other way is through automatic quantisation.

When quantising, your DAW will move your MIDI notes to the nearest whole beat or some other grid division. You can change the quantise value so that you can be more accurate with where your notes are moved to. You need to understand how note length and quantise value align, so here is a ‘conversion’ chart:

In order to choose the right quantise value, you need to look at the part you’re quantising and find the shortest note value. You then need to set your quantise to the equivalent quantise value. For example, if the shortest note was a semiquaver, or a 16th note, you would need to set the quantise value to 16 or higher. If you set the quantise value too low, some notes will move to the wrong beats within the bar.

You can apply swing to your quantising which allows you to offset every second position in the grid, creating a swing or shuffle feel. The amount of swing applied to the quantise is determined in percentages. The higher the percentage applied, the more swung it will be.

The danger with quantising is that it can sound unnatural or mechanical because it doesn’t take into account human error when playing. In some DAWs you can use random quantise which keeps some of the ‘human feel’ in the sound.

Editing Skills

• The velocity of a note describes how hard the note/key has been struck. Keeping the velocities varied can also help to keep the ‘human feel’ present in the music when quantising.

• You can change the note length in the piano roll by dragging the ends of the MIDI notes to the length you want.

• The piano roll is a graphical display of MIDI data. Time along the bottom, pitch up the side.

• The list editor does the same job as the piano roll (displaying MIDI data), but does it in a non-graphical, tabular form. It has a vertical flow, i.e. the first events (in time) are at the top of the list, and the latest are at the bottom.

• You can easily cut the notes on the piano roll with the cutting tool in you DAW. You may be cutting notes in order to change the length of the note or to split one note into two separate notes.

• Looping is when something repeats multiple times in quick succession. You can program a MIDI file to loop by using the loop feature in your DAW, or you can do it manually by cutting the file where you want it to end and duplicating the file, placing the copies one after another.

• Duplicating a MIDI file means creating an exact copy of the original MIDI file. Unlike looping, the file copy doesn’t have to occur straight after the original file in your composition; it is purely a copy that can be placed anywhere.

How MIDI Works

MIDI is “a universal language that is used by musical technology equipment and is used to send instrument and controller information."

MIDI data does not carry audio information; it’s a digital signal made up of 0s and 1s, or binary. In order for your computer to communicate with your MIDI devices, MIDI messages are sent between them.

There are two different types of MIDI messages; channel messages and system messages.

Channel messages are send to individual channels, but system messages are sent to all MIDI channels. MIDI has 16 channels, meaning that you could theoretically connect 16 individual MIDI devices from one output.

Every MIDI message contains 3 bytes of data. Each byte contains 8 bits, all of which are either a 0 or a 1.

The first byte of data is known as the status byte. It is the instruction for what type of message it is and what channel the message is to be sent to.

The second and third data bytes contain information about the parameters of the message. This information will differ, depending on what type of message it is.

This table shows the 4 types of MIDI messages that you need to know.

The ‘note on’ message is sent when the key is pressed. The data bytes contain information about the pitch of the note (sent as a note number, like C4 or A3 for example) and the velocity. The velocity value ranges from 1 to 127, 1 meaning that the key was pressed very softly and 127 meaning that it was pressed as hard as it could be pressed.

The ‘note off’ message is sent when the key is released. The first data byte contains information about the pitch and the second byte contains velocity information. The velocity will always be 0 as the note is off and the key is not being pressed, meaning there is no velocity.

The controller, or CC, message is sent when a parameter about the sound is changed. Most sliders, knobs and buttons on a synth will respond to these controller messages. Each controller has its own number assigned to it, and the message contains information as to whether it is continuous or switched.

For a continuous message, second data byte can be any value, ranging from 0-127. For example, volume controller is continuous because it can use all 128 (0 is included) levels of volume.

A switched message is either on or off. Values 0-63 will switch the controller off and values 64-127 will switch the controller on. This works for the sustain controller, as the sustain pedal can either be on or off.

This table contains some common controllers that are useful to know.

The last type of message that you need to know is the pitch bend massage. You would think that this would be a CC message but, due to the fact that these messages are constricted to only 128 values, a pitch bend as a controller message wouldn’t be smooth, as you would expect a pitch bend to be.

To make the pitch bend smooth, you need more values. It was devised that if you multiplied the MSB (most significant bit – the leftmost numbers of the binary code) and the LSB (least significant bit – the rightmost bits), you could get a smoother pitch bend. This is because the amount of values you have to play with goes from 128 to 16,384 (128×128).