MIDI Editing and Basic Mixing


Topics This Week


MIDI Editing

One of the advantages of using a MIDI sequencer to produce music is that you can edit any aspect of a musical performance or arrangement. Editing can be accomplished by selecting events and either changing when they occur or their value.

Types of MIDI Editing

Editing is used for several basic kinds of musical tasks:


The Sequencer Grid

All sequencers reference recorded events to a Bars and Beats based grid. Just as a musician will subdivide beats into smaller rhythmic units, a sequencer will subdivide a beat into smaller metrical divisions called pulses or "ticks." We think of the resolution a sequencer in terms of pulses per quarter-note or PPQN. Every sequencer has it's own PPQN reference. The resolution of GarageBand is 960 PPQN. In GarageBand this grid is set up as Bars - Beats - Division - Pulse and is represented as 001.1.1.001.

Setting the Grid


Editing Form

As we saw last week, every recording in GarageBand is stored in a region, and regions are stored in a track. Each MIDI region can be freely dragged to any location in any MIDI track. Regions can play back using different software instruments by simply dragging them to another instrument's track.

The Golden Rule of editing: Anything you want to edit must be selected. Select, then edit.

Regions can be edited the following ways:


Editing Regions

When a Region is selected, the following functions are available:

Quantization

Although we can edit the placement of individual MIDI events, it would be a painstaking. time-consuming process and is often highly impractical. We can break this type of editing down into a series of steps that the computer can follow:

Quantization is used for two purposes:

Although the common perception is that "Quantize" is a button we push to fix a sloppy performance, quantization is often best used as a tool for manipulating the rhythmic feel of a performance. Your ability to effectively use this tool depends on your understanding of various musical styles and the rhythmic nuances that characterize each.


Editing Notes and Controllers

Graphic Editing allows the user to view MIDI data as a graphic representation. A more intuitive way to view and edit larger musical events and relationships which allows for a more compositional approach to editing.

We can change the following characteristics of any note:

In addition, we can edit any of the following common expressive controls using a breakpoint line, once they have been played:


Basic Mixing

Building a Mix
Once the sound of individual instruments is set, the next step is to adjust their balance and placement. We can think of the stereo field as a two-dimensional sound stage with placement left to right as well as front to back. Basic settings for volume and panning are available on each track.

Goals for mixing:

For this first project, concentrate on building a mix using only volume and pan controls. We'll get into some of the finer points of mixing as well as effects processing later in the semester.


Review Questions
  • Name four types of MIDI editing.
  • What is the Timeline Grid used for?
  • Where are two places where the Timeline Grid can be set in GarageBand?
  • What are four ways that regions in GarageBand can be edited?
  • What can be edited when a region is selected?
  • Where is velocity edited in GarageBand?
  • What is the sequencer resolution of GarageBand
  • What is quantization used for?
  • What can be changed when editing a note?
  • What expressive controls can be edited in GarageBand?
  • What aspects of a mix can be controlled in GarageBand?
  • How do bounce a mix to disk?


Vocabulary

Transpose
Quantize
Timeline Grid
Resolution
PPQN
Region
Graphic Edit Window
Velocity
Pitchbend
Mod wheel
Sustain Pedal
Bounce to Disk