When you download an avi file over the internet, there is a slight chance that the file can become corrupted and the file is broken and doesn’t play. This is usually caused by the index, the set of rules which allow you to scrub and select a certain period of time in video, becomes corrupted. Its like missing a contents page and the page numbers from a book, you can read the book however jumping straight the correct page is impossible. This is the same with avi videos and today’s post is all about showing you how to repair broken avi indexes on your Mac.
Repair A Broken Avi Index With VLC
You can repair a broken avi index with VLC. It is the multitool for videos and should be a must have app. When you encounter a broken avi file there will be a dialog box that appears. Select the repair option to repair the index.
This warning will appear ever time you open an avi file with a broken index. If you want to repair the index every time you open the file you can do this from the settings.
To always repair the file open VLC preferences from the menu bar. Select the show all button at the bottom of the preference pane. Within the Input/Codecs option in the left hand side select Demuxers > AVI. Under the Force index creation select Always Fix.
The problem with this method is that the index is repaired but the results are not stored. This means you have to repair the index every time you open the file. We can get around with by permanently fixing the index, however an app needs to be installed.
Repair A Broken Avi Index Permanently
To repair an avi index permanently on your Mac you need to install an app called DivFix++, unfortunately this can’t be done within VLC. Its a great little app.
When you have installed the software, choose a path to save the file by clicking on the orange folder in the top right corner of the app. Then select Add Files, using the button at the bottom of the app.
Once you have added your broken avi file, you have a couple of methods to fix the file. The quickest way is to hit the fix button at the bottom of the app. You can also use the strip index, and the check errors options if you are having trouble fixing the file.
Ensure ‘Keep Original File’ is selected. Without this, the app will have trouble fixing the file. You can also have the ‘Cut Out Bad Parts’ option selected as this will provide a smoother video, but you will loose parts of your video.
After the file is processed you will have a repaired file. Go to the folder it is saved in and play the file to ensure it works. You can now delete the original and rename the fixed version.
Repair A Broken Index With Terminal
mencoder -idx input.avi -ovc copy -oac copy -o output.avi
Note that mencoder requires the installation of X11 and is unsupported on new Mac’s. I recommend you use the first two options listed in this article.