Create variable speed effects
In addition to constant speed changes, you can create variable speed effects in which the playback speed of a clip changes dynamically. For example, a clip might start in slow motion, speed up to fast motion, and then slow back down to regular speed. You create variable speed changes by identifying ranges of a clip as speed segments, each with its own constant speed setting. Speed segments can be set to any speed value, forward or backward, and you can create abrupt shifts between speed segments, or gradual transitions (also called ramps).
Note: You can’t create smooth transitions between a speed segment set to a forward speed and a speed segment set to reverse speed (and vice versa).
Apply a preset variable speed change
You can apply preset variable speed effects that break your clip into multiple speed segments automatically.
Do one of the following:
To ramp the speed down: Choose Speed Ramp > “to 0%” from the Retime pop-up menu in the toolbar.
To ramp the speed up: Choose Speed Ramp > “from 0%” from the Retime pop-up menu in the toolbar.
The selection is segmented into four parts with different speed percentages, creating the ramp effect. If more precision is required, you can manually drag any one of the four retiming handles to set the speed you want.
You can modify the transitions between segments to control how fast each segment transitions to the next. For more information, see Add transitions between speed segments.
Change the end frame of a speed segment
You can change the end frame of a speed segment in the Timeline.
When you drag the retiming handle of a speed segment, you’re adjusting the speed of the segment, not trimming it. The Change End Source Frame command allows you to trim the end point (end frame) of a segment.
In the Timeline, select a clip that has speed segments.
Choose Show Retime Editor from the Retime pop-up menu in the toolbar (or press Command-R).
Double-click the transition between two speed segments in the Retime Editor in the Timeline.
In the Speed Transition window, click the Edit button.
A filmstrip icon appears over the end frame of the speed segment.
To change the end frame, drag the filmstrip icon left or right.
As you drag, the Viewer displays the current end frame.
Create custom variable speed changes
You can manually divide a clip into segments and assign each segment its own speed setting.
Choose Blade Speed from the Retime menu in the toolbar (or press Shift-B).
The Retime Editor appears above the clip (If it wasn’t already shown), and the clip is divided into two speed segments.
To set the speed for the newly created segments, do one of the following:
Double-click the Retime Editor above one of the speed segments. Then, in the Custom Speed window, set a new speed by selecting either rate or duration and entering a speed percentage or a duration. Click anywhere outside the Custom Speed window to close it.
Drag the right edge of the speed segment in the Retime Editor to change the segment’s speed.
To create and modify additional speed segments, repeat steps 1 to 3.
You can modify the transitions between segments to create smooth adjustments from one speed to another. For more information, see Add transitions between speed segments.