I have a long video that I'd like to insert in the Blender VSE. So I open the default blend file, enable AV-sync, and add the movie strip. Somehow, the video is already the same length as the audio strip.
The default framerate is ~29.97 fps, but when I open the source in VLC it says the source framerate is about 36.
I move the playhead to around halfway through the audio strip in Blender, and it's entirely out of sync with the video. But the strips are already the same length! I tried setting the framerate to what VLC said the source's should be. Now the ends of the strips are nearly ten thousand frames apart and the synchronization problem is even worse.
I haven't been able to find suitable answers from similar questions on Stack Exchange. They're either "add a speed effect strip" (the strips are already the same length, they're just not in sync) or "make the Blender framerate match the source video framerate" (which I did).
Edit: The question marked this is marked as a duplicate as reached the same solution, but it is really a different question.