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Audio sync drifts when I try to cut

New Here ,
Sep 21, 2022 Sep 21, 2022

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So I have a video that was given to me to edit. There's only one audio track and I think it's from the camera. Here's the strange part, the audio is only in sync when I play from the beginning of the clip; however, if I play the clip forward, for example, 30 seconds later the audio is not in sync anymore. The only way to get the audio to sync with the visuals is if I play everything back to the beginning. As you can see, any cuts that I make to the audio are entirely unsynced. I can't make any edits without the video looking like an old-school Godzilla movie dubbed in English. I thought maybe I could just try to make shorter clips and perhaps the audio would be in sync if I exported them but it's not working at all. I tried rendering the audio and it won't help either. I'm really at my wit's end because none of the videos I've seen on youtube addresses this crazy issue I have right now. Please, if someone has an answer, I'd really appreciate it. PS: the video clip has no clapping for me to reference.

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Audio , Editing , Error or problem

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correct answers 1 Correct answer

Community Expert , Sep 22, 2022 Sep 22, 2022

I'm on several other forums and you're right, how to sync audio & video while recording ... and fix it after, are always "hot topics". As even when using a physical sync cable system, one camera may simply have more latency native to its recording process than another.

 

Using jam-sync tools gets you (most of the time at least) a decent start, but if the shoot goes on for a couple hours, and some cameras are stopped/started and others aren't ... well, that's busted also.

 

So this is a constant

...

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Community Expert ,
Sep 21, 2022 Sep 21, 2022

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I'm wondering if the clip is VFR ... variable frame rate? ... as this would do that of course.

 

You can check by dropping the clip on the desktop icon of the free utility info file MediaInfo  and see if it shows the file as VFR or as CFR ... constant frame rate.

 

Of course, a dead giveaway is if the file's properties in Premiere show as anything other than a "typical" frame-rate. Such as 29.212 or something like that.

 

If so, the clip should be converted in the (also free) utility apps like ShutterEncoder or HandBrake to CFR, and replace the clip in the bin.

 

If this is CFR, at times the camera doesn't go great jobs of recorcing audio and video tracks at precisely the same speed. That takes a bit of futzing to unlink the video & audio, then stretch or shrink the audio track to fit the timing of the video.

 

Neil

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Advisor ,
Sep 22, 2022 Sep 22, 2022

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This is a very hot topic. It is not always possible to synchronize the material correctly. Even if the audio and video have a constant framerate. Neil, if there are any subtle tips? I had a situation when the sound from the clip was not picked up from other cameras and it was impossible to synchronize the material.

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Community Expert ,
Sep 22, 2022 Sep 22, 2022

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I'm on several other forums and you're right, how to sync audio & video while recording ... and fix it after, are always "hot topics". As even when using a physical sync cable system, one camera may simply have more latency native to its recording process than another.

 

Using jam-sync tools gets you (most of the time at least) a decent start, but if the shoot goes on for a couple hours, and some cameras are stopped/started and others aren't ... well, that's busted also.

 

So this is a constant issue, even with pros with syncing kit in use.

 

MIke Russell's YouTube channel has some good stuff on this problem, and so does Paul Murphy at The Premiere Pro channel. Jarle Leirpoll covers sync pretty good in his massive manual for PrPro (both ebook & printed) The Cool Stuff in Premiere Pro” ...because this is crucial stuff.

 

My very first video shoot I had a good camera setup, but ... coming from stills, I had two HUGE errors, both sound related:

  • I had only one off-camera mic, used for a small part of the event, relying on on-camera mic for everything else;
  • I didn't record any ambient sound from the various places of that outdoor multi-hour event.

Between the two major errors above (and several minor ones ... sigh) ... I had great camera footage. But poor to completely unusable sound. As some of the ambient was loud enough the on-camera mic just didn't provide adequate clarity of talking voices.

 

And even the one scene where I'd had an off-camera mic, with only the one, it varied so as people faced closer to it or away. And then add in ... with no separate ambient, I couldn't even make it a cool "look at this!" thing with nice ambient as the underlying sound. Worst of all worlds.

 

And it was clear ... I didn't have a usable capture of the event. Beautiful images yes ... but video MUST have good sound or it doesn't matter, does it?

 

Neil

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Advisor ,
Sep 22, 2022 Sep 22, 2022

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Yes, sound is an important component and you need to understand how to solve problems in post-production when you work with a large number of cameras. Even with 3 there are problems. I am subscribed to Mike Russell, there are good sound tips there. I am also familiar with Jarle Leirpoll, he has the best solutions for emerging problems and their workarounds. Great articles.

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New Here ,
Nov 06, 2022 Nov 06, 2022

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Sorry for this very late reply but I tried your suggestion out today and it WORKED!!!!!!!!!!!  I'm just super grateful for this!  I will now give instructions to the camera person to change his camera settings.  Thank you so much!  Neil, you are like a super-pro!  

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