Waveforms and Audio Scrubbing

Rather than relying solely on your ears to pick up audio cues, you can use visible audio track waveforms to see a clip's sound levels. This makes it possible to edit audio clips with more precision.

To view audio clip waveforms:

• Choose Show Audio Waveforms from the View menu (Figure 10.13), or press Command-Shift-W. The waveforms appear as vertical lines on audio clips (Figure 10.14).
  
  

  Figure 10.13. Turn on the display of audio track waveforms from the View menu.

  

  
  

  Figure 10.14. Waveforms appear on audio clips (alas, not on video clips, which also contain audio).

  

  
  

To scrub audio:

• Hold down the Option key while dragging the Playhead in the Timeline Viewer. The audio plays back at the speed that you drag the Playhead, so it's likely to be sped-up or slowed-down. This lets you quickly locate an audio cue without playing your clips back in real time.
  
  

Tips

• Zoom in on the Timeline to display more waveform detail.

• Press the up and down arrow keys in a selected audio clip to temporarily raise or lower waveforms to see them better (Figure 10.15). (This has no effect on the volume of the clip.)

  Figure 10.15. Press the up arrow key to make the waveform appear bigger in a selected clip.

  

• The Timeline snapping feature works within audio clips, too. When the Playhead comes within three frames of audio silence, the yellow snap line appears.

• Displaying waveforms is fairly processor-intensive, so if iMovie is bogging down, turn them off.