Video and audio out of sync

Question

Level 1

4 points

Video and audio out of sync

I'm playing a song in iTunes on my laptop. At the same time I'm recording a musician on my iPhone 6s Plus playing along to that song from my laptop. Then I import the song and the video into imovie. I sync them at the beginning but slowly they go out of sync. Usually the video plays faster. Tried slowing it down but no luck. Everything is out of sync. I've tried this in multiple video editors as well as editing on iPhone and MacBook Pro but it's the same thing.

Any ideas?

Posted on Jul 5, 2017 3:20 PM

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Answer 1

GeeD

Level 6

9,189 points

Jul 6, 2017 5:20 AM in response to jlb2112

The problem is that speed adjustments in iMovie are too course. If you open your musician recording in the (free) Audacity app at http://www.audacityteam.org/

you can speed up the audio (without affecting pitch) with much finer control then re-save the file and import it into iMovie. Choose Effect > Change Tempo and you will see the following window:

Of course you first need to measure in iMovie what the new duration of the sound file has to be in order to be in sync..

Geoff.

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Answer 2

jlb2112 Author

Level 1

4 points

Jul 6, 2017 10:56 AM in response to GeeD

Thanks. That's a workaround I guess. But why is this happening in the first place? I play the song and play along with it, then import that song into the editor but the audio from the video does not match up.

When I align the beginning audio it only stays in sync for around 15 seconds before you notice that it's drifting slowly out of sync.

I feel like this shouldn't be happening.

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Answer 3

GeeD

Level 6

9,189 points

Jul 6, 2017 11:16 AM in response to jlb2112

Well you are recording the the audio on your iPhone and playing it back on your laptop. So you are relying on their clock rates being exactly the same which is apparently not the case.

On reflection I was wrong and you should use Effect > Change Speed rather then Effect > Change Tempo in Audacity in order for the pitch to match.

Geoff.

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Answer 4

jlb2112 Author

Level 1

4 points

Jul 6, 2017 12:21 PM in response to GeeD

I just downloaded Audacity and will give this a try, thank you again.

The problem happens even if I record on iPhone and edit/playback on iPhone. This is what I don't get.

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