30fps and 29.97fps audio problem

Gohanto

Gohanto

Veteran
I'm working on a film that was shot on the 5D with the H4n recording audio. It was cut in FCP at 30fps. I got OMF and video files that I imported and they played fine together in a 48k session.

When I exported the audio from PT, the director dropped it into his 30fps FCP session and lined up the head pops. At roughly 5:30, the tail pop of the audio was 11 frames early. To my knowledge that means the audio is running at 29.97 vs. the video's 30.

The only solution I've tried is bouncing from PT with a pull-down to 48,048 sampling rate. Same problem when the director tried it though as I think FCP simply re-sampled the audio when it reimported the track.

Any suggestions?

And how would I prevent this in the future with 30fps video?

Thanks,
 
Gohanto said:
When I exported the audio from PT, the director dropped it into his 30fps FCP session and lined up the head pops. At roughly 5:30, the tail pop of the audio was 11 frames early. To my knowledge that means the audio is running at 29.97 vs. the video's 30.
Click to expand...

29.97 is slower than 30.
 
You have just experienced the FCP x.0 frame rate bug (feature). I started a tread on this awhile back and I think there is also one on the DUC. There are a few things you can try. The problem is not you it's FCP and there is not a lot you can do. About the only shot is to wrap your file in a Quick Time wrapper that tels FCP that your footage (sound track) is actually 24fps. The only way I know off hand to do this is with Sebsky tools. Instead of putting it all down again here you can search this forum od go to my blog.
Noiz on Noise

A quick look and I realize I need to follow that post up with some specific directions. I think there are some in the DUC thread.

Anyway it doesn't always work. I did four shorts with the D5 mrkII and two we re did with a special setup in FCP that works perfectly, one the sebsky tools fixed and the first one which was finished before we found out there was an issue sebsky tools didn't solve and we had to do all the laybacks in ProTools. Others have had 100% luck with Sebsky tools so the failure may have been the editors? But I played around a bunch with this issue and it's tricky. FCP is restamping your files with the wrong sample rate in the mistaken assumption that you have been working at video speed and your files need to be pulled up to match the film speed that FCP is running at. The normal "fix" for this kind of thing is to pull down your files so when they get pulled up your in sync again. BUT Apple will "fix" you sample rate and THEN pull them up so the only hope is to fool FCP into thinking that you are already at film speed and the only way to do that is to fool FCP into thinking that you are sending it a film speed video clip. That is what wrapping it in a .mov file does. I'll try to get the update on the Blog and the link to Sebsky tools up also but if the DUC doesn't help drop me a line.

scott@askinc.net
 
OK I updated the blog with the work flow and other developments and links to Sebasky tools and the FCP Quick setup.
 
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