Working with keyframes
The normal use of some types of effect is to transform the source material in a uniform way from beginning to end. Atmospheric effects like Old film, and effects that change only the coloration of the clip, are among those in this category. Their parameters are generally set once and for all at the start of the clip. This is the static use of an effect.
Other effects, such as Water drop, depend on a sense of motion. They are likely to be effective only when their parameters are allowed to vary throughout the clip. The easiest way to this animated use of an effect is to use a preset that has animation built in, like most of those for Water drop. In this kind of keyframe animation, one or more parameters of the effect has a different value at the end of the clip than it did at the beginning. On playback, the parameters are updated after every frame to move smoothly from the start value to the end value.
Keyframing isn’t limited to just the start and end frames of a clip. Keyframes can be defined with particular values of effect parameters at any point in the clip to produce effect animations of arbitrary complexity. If, for example, you would like an image to reduce to half-size by the middle of the clip and return to full size by the end, you would need to add at least a third keyframe.
Here’s an outline of how to use keyframing to program the changes in an effect parameter during the playback of a clip.
1. Double-click a clip on the timeline to load it into its media editor.
2. Add an effect, then activate keyframing by clicking the diamond icon on the effect header if it is not already highlighted.
3. A keyframe line appears below the time-ruler. Any keyframes that have been added to the clip for the current effect to date are displayed as gray diamonds.
A keyframe is added automatically at the beginning of the clip. This keyframe cannot be moved or deleted. If the effect and preset combination you chose is animated rather than static, there will be a keyframe generated at the end as well. You can delete or move the end keyframe; if you do so, all parameter values are sustained from the last remaining keyframe to the end of the clip.
4. Set the play line to the position in the clip at which you want to establish a change of some effect parameter such as size, position or transparency.
5. Modify the parameter using the Settings panel. If keyframe editing is turned on, a new keyframe will be automatically added at the play line position. If a keyframe already exists, the parameter data it represents will be modified.
For each effect, only one keyframe can be attached to any frame of the clip. The keyframe defines the instantaneous value of every clip parameter for the frame where it is set.
Add or delete a keyframe: To add a keyframe at the play line position without adjusting any parameters, or to delete an existing keyframe at the position, click the toggle keyframe button on the far left of the transport toolbar.
Move a keyframe: To move a keyframe along the keyframe line (and thus along the timeline), click it and drag.
Jump to a keyframe: Use the arrow buttons to the left and right of the keyframe button, or click directly on the keyframe in the keyframe line, to move the play line to that position. The keyframe should highlight, indicating that it is now the target keyframe for deletion or parameter editing.
Keyframing multiple parameters
Sometimes it is desired to keyframe multiple parameters of the same effect on separate schedules.
For example, suppose you wish to change the Size parameter of an effect smoothly over the whole clip, which changing another, let us say Rotation, at several points along the way. Here are two ways of approaching this:
Method 1: Set up the Size keyframes first, then add the more numerous Rotation frames where needed. At each of these, a correct Size value will be calculated.
Method 2: Add the effect twice: once to adjust the keyframes for overall changes (Size, in the example), then another time to make multiple keyframe changes (Rotation).