AV Sync Fix allows you to fix unsynchronized audio/video movie files.
It does not edit actual encoded media sample data. It edits time-mappings. You can immediately recognize a modified synchronization and you can save it without loss of audio/video quality.
There is no need to export a modified movie file. You can overwrite it. The process of saving, without re-encoding, is very fast.
When you open a movie file, it will be copied as a temporary file for editing to the storage of your Mac. It may take a few minutes to copy depending on the file size. The requirements of available storage space size is more than twice the file size. The copied file will be deleted when the main window is closed or the app is terminated.
・QuickTime movie (mov)
・MP4 file types (mp4, m4v)
Files that requires a conversion or codec components in QuickTime Player cannot be opened. Or video tracks of them cannot be displayed.
・Optimized for macOS 10.14 Mojave
・Added support for dark mode in Mojave
・Fixed small bugs
Ratings and Reviews
Works great once you figure it out
No documentation to speak of and so figuring out how to use it can take a bit of time. I tried a couple of things and one of them worked and voila - my video was fixed. Would be five stars with proper documentation.
In my case I saw the audio and video tracks had different lengths - I subbtracted these and set the audio to start at the difference, and that did the trick.
With Family Sharing set up, up to six family members can use this app.