Correcting Audio Drift with sync video clips

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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by cyrano » Thu Jul 27, 2017 1:09 pm

Avoid the problem. Take lots of short shots...

The problem only arises with long recordings. Unless something is really broken.

The reason we're seeing more of these problems is because people tend to leave the camera running and then expect to cut out and assemble the good parts later.

50% of the work is keeping administration. Which of the 100's of clips goes where.

And I suspect there won't be a big difference between the video editor and Audacity's capabilities. The problem is known. No real magic exists yet, AFAIK.

The pro's would simply hire a few freelancers to do the tedious work. Manually, if lip-sync is wanted. Otherwise, they might just make a new sound track :lol:
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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by jimmar76 » Sat Jul 29, 2017 5:44 pm

Once upon a time, depending on what country, we shot at 24 fps or 25 fps. Our reel to reel Nagra (or other brand) recorded a sync pulse on the 1/4" tape. Life was simple.

I fear there is a problem with the frame rate being recorded by the camera, and the frame rate recorded by the external ProRes 422 HQ recording device.

In any event I did try speed changes, and a few other things but the drift seems to become more pronounced as time passes, which led me to the frame rate idea.

After a break I'll get into it again. Thanks for comments and suggestions. I may just sync up individual cuts from the clip as we edit.
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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by jonata » Tue Dec 05, 2017 6:15 pm

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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by steve » Wed Dec 06, 2017 10:00 am


That will need to be explained. How does that help?
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by jonata » Wed Dec 06, 2017 10:41 am

It shows the timecode for 23.976 video-based audio files.
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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by steve » Wed Dec 06, 2017 11:10 am

jonata wrote:It shows the timecode for 23.976 video-based audio files.

How does that help with the problem here, of "correcting audio drift with sync video clips"?

If it's not relevant to this specific topic, but you still want to tell us about your modification, then it would be better to start a new topic in this part of the forum here: https://forum.audacityteam.org/viewforum.php?f=19
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
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Re: Correcting Audio Drift with sync video clips

Permanent link to this post Posted by kozikowski » Wed Dec 06, 2017 6:59 pm

The drift rate changes with time?!?!?

Something is broken. If you can match both ends and the middle is off, that’s not a normal, expected error. It’s either broken, or something is “not suitable for purpose,” a delightful British phrase.

Shoot a test. Start an hour sound recording and clap board (or just visibly clap your hands) every ten or fifteen minutes. If nothing else, that will give the tech that fixes your stuff a good head start.

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