Why would audio that lines up via waveform playback out of sync?

I'm trying to get our closed caption files updated before we deliver and I took the h.264 of the preliminary files we made for them prior to mixing and lay in the final mix. So the .wav of the LtRt lay in at exactly the same length... I put them in ch 1 and 2 and keep the preliminary mix in ch 3 and 4. Everything lines up frame perfect visually on the timeline looking at the waveform monitor. When I go to play, it immediately starts to slip, even though the waveform is an exact match all the way until the end. Why would that happen? Both the original file and the updated .wavs are on the desktop of my new MacBook Air. It can't be the Air because I've cut entire episodes of this series on it so it can handle it. Any ideas?

Update in case anyone runs into this: The .wav file sync up perfectly on the original timelines that the video was output from. For some reason, when the sequence is exported and imported, there is something telling the sound to run slower. That's what we've figured out so far.

Have you tried playback without the waveform monitor up? Sucks CPU cycles.

- Loren

Today's FCP 7 keytip:
Advance to next/previous keyframes in a clip with Shift/Option-K !

Your Final Cut Studio KeyGuide? Power Pack
with FCP7 KeyGuide --
now available at KeyGuide Central.
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Also, if you stop playback halfway through then start again, is it back in sync? I have that trouble on an imac with complicated timelines.

Is FCP doing a time correction on the audio? Are you working in NTSC frame rates? If you are, set up easy set up to the right format before importing the audio.



www.strypesinpost.com