I have some 30fps video and some 24fps video.

I need to sync the audio from the 30fps video to the 24fps video.

If I align the beginning, by the end I have Major (more than 1 second) slip over a 30 minute video.

This seems like it should be a solvable problem, but I'm not braining too well this week.

How might you approach this situation?

@ajroach42 Possibly a good starting point for research

My shot in the dark guess is the two videos have audio tracks with different sample rates

@Kye @ajroach42 either that, or the 30fps video isn't really 30fps, but 29.97fps, and playing it back at 30fps makes it fractionally shorter? that would account for the amount of slippage observed

@ajroach42 i had a similar issue with some subtitles not matching for a movie i wanted to watch a long time ago and never could get it to work. best of luck.

@ajroach42 30 fps video isn't, it's 29.97 fps. That adds up to 3s off over a half hour.

@mdhughes That's a good point. That's going to be a pain in the ass.

@ajroach42 this might help. You’ll probably have to change the frame rate via resampling (or its video equivalent) to make them all match, either all to 30 or all to 24. Probably 24 is best. Also check if audio sample rates match!

@ajroach42 Some programs like Premiere or Vegas might have some tool inside them as well, in case you’re already using them

@ajroach42 Great! I think Handbrake, the one shown in the wikihow is free, but not 100% sure

@gianclgar That's probably my best bet, yeah. Was hoping to avoid it, but if I gotta do it I can at least do it somewhat non-destructively.

@ajroach42 At the end, when you export it, the final video will have a single fps value, so it has to happen anyway

@ajroach42 another possibility that you might be able to use is to resync periodically in the middle of the video clip so that the audio plays at a regular speed, but the gaps between the audio can be extended as needed. I don't know if I'm making sense describing this. I can see it in my head I just don't know if I'm being clear.

@vertigo If I can't figure out a way to do this programatically, so I only have to do one sync, this is what I'll do.

It looks like I'm going to be getting *dozens* of videos that are like this, though, so getting an easy way to get it to all align automatically is really preferred.

@ajroach42 Oof, yeah, I see your point. Regrettably, I don't have any automated recommendations.

If I hear anything about this, I'll pass it along.

@ajroach42 Last time I had to do this (60fps greenscreen vfx track, 23.997 fps audio scene track)
I just split the audio track with ffmpeg and then manually sync'd it.

@ajroach42 Audio doesn't work in 24 or 30 fps, so extract the audio from one video and re-add it as an audio track to the other?

@patrick right. That's what I did. But the sync is off by several seconds by the end of the video.

Did you split the audio from the video within kdenlive? If so, the time codes might have been messed up already when importing the video.
Another failure source could be 44kHz/48kHz differences.
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