MIDI has had powerful editing from its beginning. Audio has played catch-up to MIDI for years, so it's really unfair to compare the two. Audio is a complex waveform that is hard to replicate digitally. MIDI is simple text commands. Let's get into what you can do with MIDI editing.

Quantize

Since every MIDI note is a separate event, taking control of single notes and moving them around is quite easy. One of the things you can do with MIDI is called quantizing. Quantization sets up a rhythmic grid for all of your notes to follow. If you're recording a MIDI drum part that needs to be right in time, it can be hard to get it recorded right; the quantize feature can help. Quantization pulls notes that are slightly ahead or behind right onto the beat you tell it to. It makes parts rhythmically very exact. The only information you need to quantize is the speed of your fastest note division. It uses the standard musical note durations of whole, half, quarter, eighth, sixteenth, and so on. You select the quantize value (your fastest note), and it will make a virtual grid for all of the notes to cling to. It will make the part play exactly in time. Quantizing can really steady up recorded performances.

Humanize

One of the unfortunate side effects of quantizing is a “stiff” rhythmic feel. Let's be honest, no one plays every single note right on the beat, no matter how good they are. Quantized tracks can sound too perfect sometimes.

To combat this, many sequencers have added a humanizer preset, which randomly moves selected notes off the grid, ever so slightly, to simulate the imperfect performance. It does so subtly; it doesn't sound wrong. The slight imperfections in timing that it produces can take the mechanical feel out of quantizing. Some programs call the humanize command the randomize command.

Groove Templates

A groove template is another kid of quantization. Instead of drawing your notes to a mathematically placed grid like quantization normally does, groove quantization has a preset grid that creates a nice “groove feeling.” Your notes are drawn to a preset grid that is slightly out of time at certain points. Unlike humanizing, groove quantizing is preset, while humanizing is random. Again, this can add some life to otherwise mechanical sounding performances.

Looping

Do you have the same one-bar drum pattern repeating throughout most of the song? Don't play it fifty times in a row; play it once and loop it in the sequencer. This will save you a lot of time and energy. Looping is like cutting, copying, and pasting in your word processor.

Transposing

Feel like changing the key of your song after the fact? Or maybe the singer you brought in has a lower range than you thought. Your work is not lost. MIDI is very easily transposed into different keys. On your sequencer, highlight the section you want transposed and tell the sequencer how many semitones (or half steps) up or down to move it. Instant transposing.

Tempo Changes

MIDI adheres to tempo maps, and every sequencer has tempo indications. It's very easy to speed up or slow down a performance you've already recorded by just changing the song's tempo. You can do this globally for the whole track, or you can create tempo changes for only certain parts. You can even change the tempo while the sequence is playing back. Since each program is a little different in how it treats tempo and tempo changes, refer to your documentation for more specific instructions. Most programs have the tempo indicator right next to the play, pause, and rewind button, which is called the “transport.” The transport is where you control pause, fast forward, rewind, and record. Usually, tempo is coupled next to the standard transport controls. You can even set up different meters such as 3/4 time for the first ten bars, and 4/4 time for the rest. With MIDI, anything is possible!