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Chapter 12: Animation
Using keyframes you can change, or animate, the parameters of most effects over time.
Keyframing effects
About animating effects
Although commonly used to mean “move a figure across the screen,” the word
animate
is used in motion-picture
editing and compositing to mean “change an attribute through time.” In this sense, making a clip move from one
corner of the screen to another over a few seconds animates its position, while changing it from sharp to blurry over
a few seconds animates its sharpness, and changing it from a shade of pink to a shade of blue over a few seconds
may animate its color balance. Here,
animation
means “change through time,” not “moving object.”
See also
“
Adjust or reset controls in the Effect Controls panel
” on page 248
About keyframes
Keyframes
are used to set parameters for motion, effects, audio, and many properties, usually changing them over
time. A keyframe marks the point in time where you specify a value, such as spatial position, opacity, or audio
volume. Values between keyframes are
interpolated
. When you use keyframes to create a change over time, you
typically use at least two keyframes—one for the state at the beginning of the change, and one for the new state at
the end of the change.
Working with keyframes
When you use keyframes to animate the Opacity effect, you can view and edit the keyframes in either the Effect
Controls or the Timeline panel. Sometimes, the Timeline panel alternative can be more appropriate for quickly
viewing and adjusting keyframes. The following guidelines may indicate the appropriate panel for the task at hand:
•
Editing keyframes in the Timeline panel works best for effects that have a single, one-dimensional value, such as
opacity or audio volume. The Effect Controls panel is usually easier for editing keyframes of properties that have
multiple, angular, or two-dimensional values, such as Levels, Rotation, or Scale, respectively.
•
In the Timeline panel, variations in keyframe values are indicated graphically, so you can see at a glance how
keyframe values change over time. By default, values change between keyframes in a linear manner, but you can
apply options that refine the rate of change between keyframes. For example, you can bring motion to a gradual
stop. You can also change the interpolation method and use Bezier controls to fine-tune the speed and
smoothness of an effect’s animation.
•
The Effect Controls panel can display the keyframes of multiple properties at once, but only for the clip selected
in the Timeline panel. The Timeline panel can display the keyframes for multiple tracks or clips at once but can
display the keyframes of only one property per track or clip.
April 1, 2008
