Apple Final Cut Express 4 - Manual (Page 768)

768 Part IX Effects and Color Correction
Understanding Bezier Handles and Curves
When adjusting the Bezier handles that are attached to a smoothed clip, there are
several kinds of curves you can create, which result in different velocity rates.
 The steeper the curve of the Bezier handles in the parameter’s keyframe graph line
(or overlay), the faster the rate of change.
 The shallower the curve of the parameter’s keyframe graph line (or overlay), the
slower the rate of change.
The kinds of curves you can apply to a keyframe depend on that keyframe’s location
relative to other keyframes on the parameter’s keyframe graph line.
One-Sided Bezier Handles
The first and last keyframes of a group have one-sided Bezier handles. These keyframes
begin and end any dynamic changes in a clip’s parameters, and therefore they
accelerate into a change and decelerate out of it.
Constant rate
of change
Shallow rate
of change
Steep rate
of change
Bezier handle
First keyframe
Last keyframe
Bezier handle