Apple Final Cut Express 4 - Manual (Page 645)

Chapter 43 Using the Voice Over Tool 645
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 If no In point is set: The position of the playhead defines the In point, and recording
continues to the Out point.
 If no Out point is set: The end of the sequence is used, defined by the end of the last
clip in the Timeline.
If Final Cut Express doesn’t have enough available memory to record the duration
specified, a message appears when you click the Record button in the Voice Over tab,
prompting you to set a shorter recording duration.
Important: Depending on the duration specified, the sync of audio recorded using the
Voice Over tool may drift slightly, relative to your sequence’s other audio clips. This
varies depending on your audio interface and may be approximately one frame every
10 minutes. For the short clips you typically record as part of a narration track, this
won’t be noticeable.