Adjusting Rate Of Change With The Speed Graph - Adobe AFTER EFFECTS 7.0 Manual

More spatial distance between keyframes increases layer speed.
•
In layer bar mode or in the Graph Editor, adjust the time difference between two keyframes. Decrease speed by
moving one keyframe farther away from the other, or increase speed by moving one keyframe closer to the other.
Shorter temporal distance between keyframes increases layer speed.
•
Apply the Easy Ease keyframe assistant, which automatically adjusts the speed of change as motion advances
toward and retreats from a keyframe.
See also
"To automatically ease speed" on page 231

Adjusting rate of change with the speed graph

After you have set the shape of a motion path or created keyframes for a property, you may want to adjust the speed
to better simulate the natural world. Using the speed graph, you can adjust motion or the rate of change for a value
just before and just after a keyframe.
For example, you can change the motion of a layer so that it slows just before a keyframe and then speeds up just after
the keyframe, or so that it moves quickly over a certain distance and then slows down smoothly. By adjusting the rise
and fall of the speed graph, you can control how fast or slow a value changes from keyframe to keyframe.
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