Audio Track unSync After Export

Help/How To
1

Audio track seems to de-sync after being exported.
It Sounds like it is starting at the correct time and ending at the correct time
But the main action spot in the middle is now a couple frames off.

I tried setting the sample rate of the exported mp4 to match the source audio but that did not fix the issue.

Also made sure the video export frame rate matches the inputted video framerate

This couldnt be a simpler track, its just one video track and one audio track with the audio track cut down to match the length of the video track and to hit a “drop” at the correct frame.

2

That is surprising. Usually, if audio sync gets off, it stays off or keeps getting worse.

One possibility is that your source material might be variable frame rate, or your container might be difficult to seek. As a test, you could try to convert both source clips to an edit friendly format.

See here:

3

The sampled videos are not useing VFR.

Also I double checked and it dose seem like the audio plays for about a quarter second longer after exporting.

Here is a video showing my project and the output differing from the timeline

4

Thanks for sharing the video. Unfortunately, it does not give me any clues about why you might be getting different output.

Did you try my suggestion to convert the files?

5

Im not sure what a “edit friendly format” is but I did convert them both to webm using ffmpeg and still got the same results

And I tried converting the video into webm and the audio into wav with the same results as well

6

Is it? How do you know for certain? I watched the video a few times comparing the video moment you pointed out with the change in the music. They seem the same to me, but it is difficult to judge from just watching a screen recording and not having control.
Can anyone else see+hear the problem? Compare 0:23 with 0:51

7

Its off by about a frame or so and I can clearly see it in the video I uploaded.
And the whole thing dosnt work when the “drop” is off by a frame.

Here is another video where I pause right when the third “hit” happens on both the timeline and the outputed video.
You can see from what frame we are on that the output is at lease one frame sooner. (outside of the water instead of the drop happening right when we cut to the underwater shot)

Video:

9

Had to re-upload the example video to mask out personal information

Video: https://youtu.be/X2otRUuFKHY

10

I suggest to try a different editor. There is no function in Shotcut that will let you repair it yourself in the project.

11

Ok, but like why is this happening?
I can still go find a different editor but our editor just desyncs audio Dosnt seem like a good response

12

I do not know, and I do not know how to reproduce it. Also, I do not want your video file to try to reproduce it because I think it is ugly and insensitive. I choose not to view it any more. Maybe you can figure it out by studying the source code.

14

Maybe the sync problem is in your player. One frame is a pretty tight tolerance and most humans can not perceive a one frame audio offset. As a test, you could open the exported file in Shotcut to play it and see if the offset also appears when played in Shotcut.

15

This is it!

Maybe the sync problem is in your player.

When I add the exported file back into the editor the audio is synced back up.
So i guess the audio in the editor for me is about a frame off

16

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