iMovie You can extend the audio from one clip so that it plays over the beginning of the following clip (L-cut), or so that it plays over part of the preceding clip (J-cut). Modifying sound in this way can be used to artistic effect, to punctuate transitions between clips, and so on.
To extend or shorten a video clip’s audio:
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In the Project browser, move the pointer over a video clip and choose Precision Editor from the Action pop-up menu (looks like a gear) that appears in the lower-left corner.
You can also double-click the gap between two clips with no transition (indicated with a transition icon), between them. The graphic below shows several styles of transition icons.
The Precision Editor opens. It shows the clip you started from (A, below) at the bottom and the one before it (B, below) at the top, or it shows the clips on either side of the gap you clicked. The transition point between the two clips is represented by a vertical blue line (C, below). The shaded areas of the clip (D, below) to the right and left of this line represent portions of the clip that you didn’t use in your project.
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Click the Audio Waveform button (shown below) at the top of the Precision Editor.
Blue audio waveforms appear below the clips.
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Do one of the following:
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To adjust where audio from the clip before the transition point ends, move your pointer over the portion of the vertical blue line that’s in the waveform at the top of the Precision Editor; when the pointer turns into a resize pointer, drag the line to the right or left.
Dragging to the left makes the clip’s audio end before the video clip. Dragging to the right makes the clip’s audio keep playing while video from the next clip plays (it overlaps the next clip).
As you drag, the vertical blue line fractures, as shown below; just the portion in the blue waveform should move.
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To adjust where the audio from the clip after the transition point starts, move your pointer over the portion of the vertical blue line that’s in the waveform at the bottom of the Precision Editor. When the pointer turns into a resize pointer, drag the line to the right or left.
Dragging to the left makes the clip’s audio start while video from the preceding clip is playing (it overlaps the previous clip). Dragging to the right makes the clip’s audio start playing after the video has started.
As you drag, the vertical blue line fractures, as shown above; just the portion in the blue waveform should move.
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To simultaneously adjust audio from both the clip preceding the transition point and the clip following it, move your pointer over the vertical blue line in the waveform at the top or bottom (either one is OK) of the Precision Editor. Hold down the Shift key, and when the pointer turns into a resize pointer, drag the line to the right or left.
The line doesn’t fracture. Using this method, audio from one clip ends just as audio from the next clip begins, with no audio overlap.
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