Adobe 65021048 User Guide - Page 288

282 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