AV Sync Fix allows you to fix movies that are out of sync audio/video simply by dragging the timeline or in detail by entering numerical values.
The app does not edit actual media sample data. It edits time-mappings. You can immediately see the effect of the fixes and overwrite it without loss of audio/video quality. It's very fast. There is no need to export as another modified movie file.

■ The minimum storage space required
When you open a movie file, the app copies it to the storage of your Mac as a temporary file for editing. The app needs available storage size more than twice as much as the file size. Copying may take a few minutes depending on the file size. The temporary file will be deleted when you close the main window or quit the app.

■ Supported Formats
- QuickTime movie (mov)
- MP4 file (mp4, m4v)
But the app cannot open/play the following files.
- Files which QuickTime Player cannot open
- Files which require any conversion or codec components in QuickTime Player
- Protected video/audio files (e.g. Movies, TV Shows downloaded from iTunes Store or TV app)

Please backup your data before using this app, just in case an unexpected error occurs.

What’s New

Version 2.3

・Usability improvements
・Fixed an issue that may cause problems with dragging the timeline

Ratings and Reviews

3.0 out of 5
2 Ratings

2 Ratings

Gramsterix ,

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.

joemag3 ,

I hate when software takes over

This software did help me correct some video sync problems. Unfortunately, though, double-clicking on a saved file causes AV-Sync to open, instead of Quicktime player. I hate it when software does that. It forces me to throw the app in the trash after every use, just so it will stop acting like the default app for all my movie files. Seriously annoying.

Developer Response ,

It seems that the default app of a file you saved is set AV Sync Fix. Most files have an assigned default app that opens the file when it is double-clicked in the Finder. You can change it for a specific file type. Please try the following to change it to QuickTime Player.
1. Select a saved file in the Finder.
2. Press command + I keys to show the file info window.
3. Choose QuickTime Player in the "Open with:" pop-up button.
4. Click the "Change All..." button if you want to set it for all other same extension files.
AV Sync Fix does not set the default app of files to AV Sync Fix when saving.

App Privacy

The developer, Tranquillity Base, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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