Apple Final Cut Pro 7 - Manual (Page 905)

If keyframe recording stops before the end of a clip, the audio or pan level of the remaining
duration of that clip depends on whether or not there were already keyframes in the clip.
• If there were no keyframes in the clip prior to recording keyframes: The audio level or pan
overlay remains at the level of the last recorded keyframe for the remaining duration
of that clip.
Playback stopped here.
• If there were keyframes in the clip prior to recording keyframes: The audio level or pan
values are interpolated from the level of the last recorded keyframe to the level of the
next keyframe.
Playback stopped here.
Modifying Recorded Keyframes
After you’ve recorded keyframes for a series of clips on a particular track, there are two
ways you can make modifications to the levels you’ve set with the Audio Mixer: by using
the Audio Mixer or by modifying keyframes in the Viewer or Timeline.
905 Chapter 56 Using the Audio Mixer