Apple Logic Express 8 - Manual (Page 416)

416 Chapter 16 Editing MIDI Events in the Piano Roll Editor
 The vertical position of note events indicates their pitch, with those nearer the top of
the Piano Roll grid being higher in pitch. Chords are displayed as a vertical stack of
note rectangles. The alignment of notes in chords is not always identical, as not all
notes in a chord may be struck, or end, at the same time.
 The length of MIDI note events is directly related to the length of the rectangles, so
notes such as; hemidemisemiquavers (1/64th note), quavers (1/8th note), crotchets
(1/4 note), minims (1/2 note), whole notes, and so on can be easily recognized.
Making Use of the Grid
The grid provides a valuable reference for note lengths: You can see both the start and
end positions of note events, aligned with the time values shown in the Bar ruler. This
simplifies note length editing.
The default grid lines shown are:
 A black line at every bar and beat.
 A light gray line at every division value (you can alter the division value in the
Transport).
You can alter the appearance of this grid and other aspects of the Piano Roll Editor
(see “
Customizing the Piano Roll Editor ” on page 434).
The vertical keyboard on the left side of the Piano Roll Editor indicates note pitches.
Horizontal black lines run across the screen between notes B and C, and notes E and F.
These lines are very helpful when transposing notes by dragging them up or down.
Understanding Note Velocities
Each note event features a horizontal line that runs through the rectangle. The length
of the line—in relation to the total length of the note—corresponds to the velocity
value of the note (up to the maximum value of 127). Velocity denotes how hard the
MIDI keyboard was struck when the note was recorded. This also usually indicates how
loud the note is, within the range of 127 possible values, with 127 being the “loudest.”
The Piano Roll Editor also indicates note velocities with different colors.
This makes it very easy to see the overall range of (and individual note) velocities in a
MIDI region. As you change the velocity of MIDI notes, the color of selected notes
changes in real time.