audio / video sync problem with mp4 720p @ 30 FPS video


I'm new here, but use kdenlive for several years now, and am happy with it.

I'm currently working on a song video clip. The final format is 720p @ 30FPS.
As the song is quite long (16 minutes), I've split it into small parts (like 10 of them), which I render, and then I've a big project in which I import every renders and render the final thing, with the audio file coming out from the studio.

The point is, for one of the small parts (the one called Intro), I've got an audio / video unsync in the end.
I've verified each step:
- audio / video sync is OK when playback in Intro.kdenlive project
- audio / video sync is OK when playing Intro.mp4 file (which is the file in which I've rendered the part)
- audio / video sync is OK when playback the main.kdenlive in which I've imported Intro.mp4
- audio / video sync is NOT OK when playing main.mp4 (which is the file in which I've rendered the whole project).

This could be understandable (or might be) if this problem occured on every mp4 file I've imported in main.kdenlive, but actually, it only occurs on [b]this[/b] Intro.mp4 file, and all the other parts are OK.

I'm pretty sure it has to deal with frames problems several people are talking about when you googlized, or when searching on this forum: , but I couldn't figure out how I could fix this, or find a workaround.

I've been on irc for two days, but no answer, so I came up there.

I would greatly appreciate your help, I'm a bit in a hurry for this video clip, actually!! ;)


No idea?

I've answered to this post, cause I think this problem is really related to that frames pb:

Thanks a lot for your ideas.

The clips that have the matching/static frames at the start caused audio sync problems because audio started from the very beginning and not 5 or 6 frames in, when the video started.

You said " I've got an audio / video unsync in the end." If the audio slowly goes out of sync, this is a different problem. With a steady sync error, it was easy to extract the audio from the clip, place it in the timeline, adjusting it to match and mute the video clip.

You said that the first render of "intro" worked fine but the second did not. As a quick work-around, I would try this. Open up the intro.kdenlive project and just add the next rendered parts to that. That way "intro" only gets rendered the once. Try a little test with a selected zone.