You control the rate of change for apparent camera movement at each keyframe using the Velocity parameter category.

The Avid Pan & Zoom effect uses Velocity In and Velocity Out at each keyframe to modify apparent camera speed as it pans across the image between keyframes. It modifies changes in the Zoom Factor setting in the same way.

The gradual acceleration at the beginning of movement is ease in, and the gradual deceleration at the end of movement is ease out. Acceleration, a global parameter found in other effects, adjusts an effect's speed over time by having the effect ease in and ease out at the first and last keyframes respectively. Velocity is a keyframeable parameter and it gives you more options than does Acceleration. For a description of all the Velocity parameter options, see Velocity.

The Velocity parameters divide the time between keyframes in half. Velocity In controls the rate of movement in the first half; Velocity Out controls the rate of movement in the second half.

Procedures for setting a simple ease in and ease out, and for setting a constant speed for an effect, are described in Using Ease In and Ease Out and Creating a Path with Constant Velocity. For information on the Velocity parameter options, see Velocity.