Recording direct to FCP-Audio Sync

kwoff

kwoff

Well-known member
Last weekend I used my HVX to shoot about 5 1/2 hours of 720p 24 footage direct to a G4 PowerBook using FCP. Two clips were 2 hours long and the other two were 45 minutes each. My settings included having FCP strip out the redundant frames automatically upon capture. It all went without a hitch (except for a couple of minor operator errors), but there was one odd anomaly--the audio on three of the clips was 6 frames ahead of the video and on the other clip it was 3 frames ahead. The audio remained exactly the same number of frames out of sync for the duration of the clips, so it was easy enough to fix in FCP merely by sliding the audio +3 or +6 frames.

It was so easy to fix this that it really isn't a problem, but I was curious if anyone else has experienced this and what others think might be the cause. The only thing I could think of was that, since I had FCP stripping out the redundant frames, this may have caused an initial small delay in recording video as the processor took some time to calculate which frames not to record. Any other ideas? I had my camera connected to a FW 400 port on a PCMCIA card and a mobile FW 400 Smart Disk HD connected to a built-in FW port. The PowerBook was a 1.5Ghz G4 with 1GB of RAM, FCP 5.1.2.

Thanks,
Kevin
 
In your capture presets, there's an "offset" setting. Not sure if that would help or not. Check the FCP user manual, volume 4, chapter 25 for details.

I'd also suspect that there was some latency in the audio caused by your set up. What was the set up for recording your audio?
 
BenB,
Thanks for the response. I don't think my audio setup should have caused any latency--it was very simple, a camera-mounted CK 93 plugged into the camera's audio input channel 1. I looked at FCP manual concerning the capture offset setting, but it seems to relate to an offset to sync video and timecode.

I did notice in the manual though that there is a device control preset for DVCPro HD. My reading concerning capturing direct into FCP said device control should be set to noncontrollable device, and that is what I used. The recommendation to use noncontrollable device may have related to earlier versions of FCP. Could this be the cause of the the sync issue?

Kevin
 
So your recording with a mic directly into the HVX? Ok, eliminates that problem. The DVCPRO-HD device control should work. Especially since you're not actually controlling the camera, just reading the video stream. Try it, see what happens!

On the bright side, it's a really easy problem to fix in post.

But it is dang odd!
 
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