[LAU] OT - syncing partially out of sync video and audio in existing files

Hi, sorry for abusing this list for a mostly video editing question, but I didn't find a proper list and knew that we have some video people on this list. I'd like to fix some videos that have partially out of sync video and audio, meaning that beginning at a certain point in the video the audio is suddenly out of sync by a couple of seconds. There's no constant change, the delay seems fixed once it's there. I wonder how to fix such a thing. The files are xvid encoded videos and vbr mp3 audio inside avi containers. I thought it should be reasonably easy to cut and move the audio (re-encode if unavoidable, but I know it's in principle possible without) and put it back in a container, but I didn't manage. Can someone recommend a program/workflow that would allow this? I tried: - Avidemux: seems like actual editing is not what this program was written for, couldn't figure it out, but it seems close - openshot: couldn't figure out how to separate video/audio - kino: seems to only work with DV-files, apparently takes ages to decode the file, doesn't seem to be what I need - openmovieeditor: I figured it might work by dragging the file to both a video and an audio track, but I got extremely garbled audio output, no idea what's wrong - cinelerra-cv: Doesn't start. No error message, it simply shows no window, nothing. Well, it does something with the screen, but it shows nothing. - pitivi: Doesn't seem like it can play back the video. I can drag the video to the tracks and it starts to draw a waveform, I guess no video thumbnails because of: gst.ElementNotFoundError: pngenc Doesn't seem to be able to play the video. - kdenlive: would require me to install 30 additional packages, total about 200MB, no thanks. I thought it would be a simple task, really nothing fancy. Seems like I was wrong. Regards, Philipp