Trim objects in the Timeline track area
Trim an object’s timebar when you want to shorten or lengthen its duration in the Timeline. You can trim the beginning or end of the object by dragging from the left or right edge of the bar (the In and Out points). You can also trim an object by using menu commands and corresponding keyboard shortcuts. You can trim multiple objects simultaneously, and you can trim on the fly while your project is playing back.
Note: Video and audio objects cannot be trimmed to be longer than the duration of their source media. To extend a video or audio object beyond the duration of its source media, you must change the object’s End Condition to Loop, Ping Pong, or Hold in the object’s Properties Inspector. This limitation does not apply to other objects, such as still images, cameras, text, and shapes, all of which you can extend without restriction. You can also change the effective duration of a clip without adding or removing frames, by changing the clip’s playback speed. For more information on the Timing controls, see Retime media overview.
When you trim a video object in the track area, Motion provides a visual representation of how much additional footage is available in the object’s source clip: a dimmed extension on either end of the bar indicating that unused frames exist in the source video clip. If you see no dimmed extensions when you trim a bar, there are no unused frames in the source clip. Consequently, you cannot lengthen the object (unless you change the object’s End Condition in the Properties Inspector for the clip).
Trim an object in the timeline
In the Timeline track area, move the pointer to one end of the bar you want to trim.
The pointer changes to a trim pointer.
Drag the end of the bar until it reaches the frame where you want the object to start or end.
As you drag, a tooltip indicates the new In or Out point, and the new duration of the object.
Trim an object and snap its In or Out point to neighboring objects
Press Shift as you drag the edge of a bar in the track area.
Vertical lines appear in the track, corresponding to the In and Out points of other bars. The active bar snaps to these lines as you drag.
Trim one or more objects via the Mark menu
Select one or more objects to trim.
Place the playhead at the frame where you want the new In or Out point.
Choose Mark > Mark In (or press I) or Mark > Mark Out (or press O) to set a new In point or Out point.
All selected objects are trimmed to the new point.
Trim an image or video layer without trimming its applied effects objects
You can trim a layer without affecting the duration of its applied effects objects (masks, filters, and so on).
Hold down the Command key while you drag the edge of the image or video clip.
The object is trimmed independently of its applied effects objects.