What Is Quantization?
It’s one of the common and most useful features of music software, but what is quantization?
These days, the modern DAW (digital audio workstation) software package has many powerful features that have evolved out of the hardware studio. Whereas, once upon a time, the hub of a computer-based studio was a MIDI sequencer, which simply controlled MIDI hardware, nowadays, the DAW does everything from running virtual instruments and effects, to recording audio tracks and much more besides.
Some features have remained a constant throughout the DAW’s evolution, however. MIDI still features at the heart of most software packages, and among the many MIDI edit functions quantization is still a key tool. It may sound like the sort of fate Doctor Who may face at the cliffhanger end of an episode, but what is quantization?
Off the grid…
To understand how it works, it’s worth taking a look at how MIDI works. Let’s imagine you have a MIDI keyboard connected to your host computer. When a key is pressed, it sends out digital information about the note pressed. At its simplest, this will comprise a ‘note-on’ message for that note, and information about velocity (how hard it has been pressed). When the key is released, the keyboard sends a ‘note-off’ message. Essentially, it tells the equipment it is connected to when a note starts, when it ends, and how hard it is pressed.
A software sequencer uses a metronome tempo so that tracks can be put together with parts perfectly in sync, and in time. It also means that, once recorded, tempo can be changed with recorded MIDI events changing tempo accordingly. With me so far?
The thing is, playing perfectly in time is a lot trickier than you might think. This is where quantization comes in. Put simply, quantization snaps recorded events so that they start perfectly on a tempo grid of pre-set resolution. Phew, that was a bit of a mouthful- let my put it a different way. Quantising MIDI parts to a 16th note resolution will move the selected notes or events so that they start on the nearest 16th note.
Here’s a demonstration.
1. Here we have a simple drum part that has been played in without any quantization. You can see that the notes are slightly adrift from the tempo grid.
2. We quantise to the nearest 16th, and all notes snap to the grid.
Though quantization is perfect for situations where perfect timing is essential, it should always be used with a degree of care. Real, human performance has slight timing imperfections, and it is these that give them their expressive feel. Be careful you don’t remove the ‘life’ from a performance with quantise…
Groove quantise is a particular type of quantization that takes into account the rigidity of standard quantise, and the ‘human’ element of performance. Rather than quantising to a fixed, even grid, it employs a groove template, usually created by a performer, but sometimes derived from classic drum machines and samplers.
When quantise is employed here, notes are shifted so that the fit the unique swing or feel of this template, making the performance less rigid. Reason’s ‘Groove Mixer’ is a great example of this.
Quantization is a powerful tool for ‘tidying up’ recordings, and adding unique feel to lifeless performances. Plus, these days many DAW packages provide quantise functions for audio, too.
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