Syncing Audio in FCP

G

gillatineny

Active member
Hey Im running FCP 7.0 on my mac pro and I am attempting to sync audio shot from an HVX at 29.97fps with video shot at 30FPS on a cannon 5D. When I finally link the beginning of the clip it seems to slowly become off snyc a few minutes down the time line without any time or clip breaks.

1. Could this be because the HVX audio is not true 30fps? Would this explain the reason why? Or am I just tripping?

Any thoughts or suggestions would be greatly appreciated


Thanks

-Sean:violent5:
 
That's right. I believe the solution is to slow down the non 5D audio by 99.9% if you are working in a 29.97 sequence (and have converted your 5D footage to 29.97). Alternatively you can change your FCP sequence preset to work in 30fps to match the 5D footage. Here's an article that talks about this.

I don't have a 5D, but I remember people talking about this.

I believe the latest 5D firmware update changes 30fps mode to record at 29.97 so you won't have problems like this in the future.
 
Thanks for the advice....I went through and changed the FCP sequence preset, however do you think I need to convert the pro audio to 30fps as well?
 
I think I was wrong in describing the problem in my original reply.

It seems that there is a problem with FCP when you change your sequence preset and then import audio if you are normally using NTSC. Even if you change your sequence to 30fps, FCP still assigns a rate of 29.97 to the imported audio (I'm guessing it's really the capture preset at fault here). So if you normally work with NTSC 29.97, but then have to deal with 5D footage by changing the timebase of a sequence, it causes problems with the audio still acting like it's 29.97 and not conforming to 30fps, hence going out of sync at the end.

The solution to this is to create a 30fps easy preset and make sure and restart FCP and work with a new project. This is described in the article I linked to in my first reply and further elaborated by that author in this article. The other solution is to change the speed of the extra non-5D audio tracks to %99.9 (which I'm not sure is even possible with the new speed tool in FCP7).

Anyway, I thought I'd clarify this. I really don't have experience with this and I'm just going by what I've read so far.

Going back to your problem. The "standard" solution to frame-rate mismatches in video is to convert one of your footage to the other frame-rate. In this case either convert your HVX footage to 30fps or your 5D footage to 29.97.

But audio doesn't really have a "frame-rate", it's meta-data, only bit-depth and sampling-rate affect the audio. If you start converting the audio, it'll start to degrade, possibly very noticeably. So I'm GUESSING that if you go through the steps described in those links to create a "proper" 30fps easy setup, then you'll just be able to import the audio tracks from the HVX into the 30fps sequence and it should line up correctly. Maybe you'll have to export the audio tracks out of FCP first (to break any possible links with the video?) and import them again, I'm not sure.

The other alternative would be to convert the 5D footage to 29.97 first.

I'm hoping that someone else will pitch in here because this isn't something all that familiar with. I apologize in advance if any of this ends up being incorrect information.

[Edit:]
Another article to check out (point #5)
 
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Cools....I appreciate your input. The articles you directed me to definitely gave me some help and I appreciate your insight into the matter as well. I set up my time line at 30fps like the article said and now I'm attempting to convert the audio frame rate to 30fps, even though it seems to not make sense, it is worth a shot. I have done a few already and they sound fine in QT player. I just haven't tried to sync them into the FCP time line yet. Hopefully there will be no audio degradation. If not I'm going to try it another way.

Anyone else have any experience with this issue?
 
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