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Frame rate adjustments question, audio drifting out of sync
Hi,
I’m relatively new to FCP, and am working on a multi-cam concert video, to be synchronized to an official audio track. All of my content is user-sourced – aka, it varies in frame rate, quality, etc.
I have two questions, which I feel may be related – but I very well could be wrong. First, is there any way I can batch process my content to bring it to a unified frame rate (eg 29.97)? Now, my next question is about the project itself… all my audio sample rates are 44.1 KHz, and I have gone with a 29.97 fps timeline, and I’m finding audio in sync with video at one point, may be off by about 1.5-2 seconds within about four minutes. If anyone could please advise as to whether I need a unified frame rate (rates range from 23.02 fps to 29.97), or can help me with my audio issue, I would be greatly appreciative. This is my first post here, and I look forward to posting more!
Ben
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11 Replies
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generally FCP doesn’t do a fantastic job of adding or removing pulldowns (23.98 to 29.97 and vice versa). what you should do is first convert all the non 29.97 material to 29.97 using something like compressor or shake to do it. unless you are fine with the way FCP does it of course. after you do that make sure you are fully rendered. if sync is still off after that we can look at other issues, but you should convert your footage first…
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Thanks Brian,
I just did a test – converted a video file from its original format to an Apple Intermediate Codec encoded (I hear that’s best for minimal rendering time) 29.97 fps file, and am still losing my sync unfortunately. You used the term fully rendered – I have no red bars above my video, but I do have grey bars, which according to the Sequence menu is ‘Rendered Proxy’. Is this rendered enough, or must I check off ‘Fully Render’ and let it work?
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in order to eliminate other potential issues, you should FULLY render all V and A first, then check your sync. oh and are you able to check your sync on an external monitor? sound like you are not able to but had to ask.
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Perfect, I’ll run the full render then. I will try and source an external monitor, as I can see where it would come in handy in terms of workflow. That said, it’s quite noticeable on the laptop screen that there is a sync issue by the end of the roughly four minute clip, when it’s spot on at the beginning.
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Thanks Brian, I will run a full render and try and obtain an external monitor – on a 17″ MBP it’s pretty visibly off, but you never know. In any case I feel like it’d be a worthwhile investment… do you have any suggestions for a decent quality external monitor mainly to be used for projects such as these?
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44.1khz is not the right rate for video editing in FCP. All material and sequence settings should be 48khz. Don’t just change the sequence settings.
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Thanks Michael – I know for resampling my audio I can use QuickTime Pro or iTunes, is there a recommended (and hopefully expedient) way to resample the audio contained within my 29.97 fps AIC files?
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It sounds like mpeg streamclip should be able to do the audio conversion you need (for free!). The monitors I have been fortunate enough to use have been from flanders scientific, or JVC surprisingly. But are 2k+. The flanders have built in scopes.
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Also you should try to pinpoint the frame where you begin to fall out of sync. add an edit there (B or BB to get all tracks). go to the beginning of the new edit and play from there. then is it still out of sync? does FCP hang up? i’m determined we can solve this man! 🙂
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AIC is a legacy codec. ProRes 422 would be a better choice. The sample rate should have been 48khz from the cameras so I am not sure why there is a need to change them. What did you shoot with?
Compressor also does an excellent job at batch converting audio from 44.1 to 48khz.
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