Automatically fix audio sync for your videos. Should work on any linux system, as long as ffmpeg is version N-78176-gb340bd8 or newer, the ffmpeg extensions are installed, and ffprobe is installed. This will only work with raw video footage (i.e directly from the camera/source, no post-processing whatsoever.)
clapperboard.sh (--dry-run) /path/to/video /path/to/fixed/video (--dry-run will only show you the audio offset, and not correct it)
Well, here's the secret. A lot of cameras, apps, and audio recording devices will embed the audio offset (in a really weird format) inside of the video. Even VLC doesn't seem to read the audio offset. clapperboard uses ffprobe to extract this offset, parse it correctly, and then corrects it. This is why it doesn't work with non-raw footage: the converting software ignores the offset and encodes the video, discarding it.