Consumer footage conversion/stall/sync issue

Working in FCP 6.0.6.

I'm helping a school music director edit a holiday music concert together. I've had to convert some 1280x720 mpeg4 footage shot on a Kodak consumer camera to use as a B-camera with footage shot on a Nikon D90. Everything was converted to AppleProRes 1280x720 @ 29.97.

The D90 footage is fine and audio syncs. The Kodak footage plays for a while then begins to stall and then freezes during play. If I restart playback, footage resyncs and plays for a short while then stalls again. If I export my edit, the Kodak footage edits are out-of-sync with the audio even though they were in-sync when edited in the timeline. It's been a nightmare. It's the ole 'favor for a friend' wishing I hadn't syndrome. :-0 HELP!

Ouch, ouch. In my own experience, that's a QuickTime data mess of some kind. I've seen it with footage screen-captured with SnapzPro, where one part of the clip plays in the Viewer as you're doing three-point editing, but after rendering in a timeline it turns into another part of the same clip. Even if the first generation of the captured clip is an editing-friendly format and codec (eg. QuickTime movies constrained to 720x480 at DV NTSC, 29.97fps), it still shifts and changes.

What software did you use to convert the clips to ProRes?

Honestly, I, another editor and three assistants couldn't figure out a way around it. Resaving the clip, re-exporting the clip -- no help. We just had to consider any unrendered clip to be inaccurate, and only perform edits after rendering a much larger chunk of the clip, or we can't judge the decisions properly.

Did you do a "master sync sequence" where all A and B camera clips were synced? If so, try exporting the entire B-camera -- black spaces included -- as a self-contained full-quality movie file in the ProRes codec, same one you're editing with. Then try editing with it. There's a chance data will still shift, but the likelihood may be lower.

Another method is to redo the conversion from the MPEG-4s and see if the problem persists.

Both ways would mean any edit you've already done with the MPEG-4s is gone; you'd have to conform the new clips manually. But since your old cut wouldn't sync up anyway, the old B-camera edits are of limited value, anyway. Plus, you can always just use the "holes" in your A-camera to find where the B-camera clips go.

If anybody else has a better workaround for this, I'm all ears.


www.derekmok.com

Thanks Derek for your quick reply. I took all of the original mpeg4 footage and put it into FCP to output it separately from timeline. I reimported the converted footage and adjusted the edits to match the original. Now I am outputting the final edit in segments (by song) instead of the full concert and that seems to help. Since the program is 2 1/2 hours, the Mac seems better able to handle short outputs better. I'm half way done and no slips. Thanks for your help.

Could this be an audio sample rate problem ? I can't see why this would make the B-camera footage 'stall' exactly but it would seem likely that the consumer camera could have been recording at 32K. I'm no expert on this, but I think I'm right in saying that 32K footage rendered in a 48K timeline will go out of sync.