Understanding keyframes

Premiere uses keyframes to change an effect over time. A keyframe contains the values for all the controls in the effect and applies those values to the clip at the specified time. By default, once you apply an effect to a clip, Premiere creates a beginning and ending keyframe with the same value, but by applying different values to keyframes, you can change an effect over time. Premiere automatically interpolates the values of the controls between the keyframes, using a linear progression. This means that you don't have to create a keyframe for every frame in the clip.

For example, suppose that you wanted to use the Crystallize effect and have it increase and then decrease over time. In this case, you would need to set three keyframes--the first with light crystallization, the second with more significant crystallization, and the third with light crystallization. Because Premiere automatically interpolates the distortion between each keyframe, the crystallization will gradually increase (linearly) between the first and second keyframes and then gradually decrease between the second and third keyframes.

Note: Some Premiere effects are not keyframeable and cannot be animated.

Applying Effects > Understanding keyframes