Apple Final Cut Pro 5 - Manual (Page 126)

Chapter 9 Timeline Basics 125
II
Track Display
 Show Keyframe Overlays: Select this option to display opacity overlays (thin black
lines) over your video tracks, and audio level overlays (thin red lines) over any clips in
the audio tracks of the Timeline. These lines indicate video transparency or audio
levels. For more information, see Volume III, Chapter 13, “Adjusting Parameters for
Keyframed Effects.”
You can also use the Clip Overlays control in the Timeline to show or hide overlays.
 Show Audio Waveforms: Select this option to display audio waveforms superimposed
over audio clips in the Timeline. You can also toggle audio waveforms by pressing
Option-Command-W. This option is also available in the Track Layout pop-up menu
in the Timeline.
Audio waveform
Without audio
waveform