Audio/Video Desync after Export

I have been using Shotcut for awhile to record gameplay. Never had a problem with it until a couple days ago. Suddenly, I am getting poor syncing once the video has been exported.

  • All of my videos have been created with Nvidia GeForce recording, both the ones that work fine and the ones now going out of sync.
  • The videos play fine in Shotcut initially, everything is properly synced.
  • Have used the same export settings for all videos.

After reading through the forums, much blame is placed on the shoulders of variable frame rates. So, despite having not run into this issue on any of my other variable frame rate videos (prior to this video, I’ve ignored the warning Shotcut gives when adding raw footage to the playlist and the export was fine) I decided to do the conversion Shotcut prompts. After 9 hours, and going from a 40GB source file to over 400GB, I had my constant frame rate file. I played through some of the footage: beginning, some random snippets in the middle, and the last cutscene of dialogue to random check for syncing. All looked well so I snipped the first 9 minutes, watched the full 9 minutes of footage to ensure that it was completely synced (it was) and exported.

And the exported version is still out of sync.

You haven’t provided any information about your project, source files, computer, Shotcut version number, etc…
Please read through this tutorial.

I do suggest making sure your NVIDIA and GeForce Experience is fully updated. With no information… assuming you have Windows, and possibly RealTek for your audio drivers, update those as well, even if you have to from the manufacturer’s website. When I had audio sync issues, updating the driver manually from the website solved my issue when I had audio desync.

Try restarting your computer before you export with nothing else running.

Does anyone have a Variable Frame Rate short video for me to download please?

None of my devices can generate VFR videos. Without a VFR video source, I can not even make a VFR short video (none of the converters can convert CFR down to VFR)

I want to test my proxy_tools and see how it handles this user’s case.

Yes, I can help you @KKnBB!
I have an old low-budget actioncam which is recording in VFR, that’s what it says in the technical data of the operating instructions.

@DvS Thanks for your help. I googled around for a while not finding a sample to download anywhere. You might be the first person in the world who has ever tried to upload a vfr video on purpose.

But I regret to tell you that the video you posted looks like a vfr (fps=30.122), but it is not.
image
Meaning the “total frames” divided by “seconds” is not an integer, but each frame holds the same amount of time without changing. The “VFR:0.00000” means 0% of the frames has changed its duration. It is a cfr.

For a true vfr, the ffmpeg would show something like this:
image

It is funny that on this forum, I read tons of posts people have got troubles with like endless amounts of VFR videos. Google showing millions of pages discussing the vfr video. But I can’t even find or generate a single piece in my life. :joy: fail of the week.

VFR Video.

I’m sorry that I trusted the manual of the cam! :frowning:

Hi @heaven13, I recently had an audio sync issue. This thread may be of interest:

Sadly, I realize there is no good way to convert vfr to cfr.

What the framerate the cfr is gonna pick? average? peak?

  • Using the average, many frames will be dropped in dynamic scenes.

  • Using the peak is crazy. In vfr some frames are 1ms apart meaning at that moment the “peak framerate” is 1000+fps. No normal cfr file can handle 1000fps.

So there is no lossless way to convert vfr to cfr.

@sauron oh hey yea I downloaded the file from your earlier post, thanks!

And after the testing I get the conclusion that there is no perfect way to convert vfr ==> cfr, as I stated in the post above.

Have you tried HandBreak. It gives you a choice of VFR or CFR and which framerates to use.
https://handbrake.fr/