Troubleshooting long audio files
The Repair Kit will often create long audio files (over 15 minutes), that may have a strange behavior when opened with QuickTime and other editors:
The file can take a very long time to open, fail to navigate correctly, hang or crash QuickTime, report inconsistent duration and times, or become silent after a few seconds of playback.
Silent playback problem is usually solved by just stopping and resuming playback.
The cause seem to be the way audio samples are distributed inside the file. Indeed, when audio scraping is performed, Repair Kit only creates one enormous audio sample that contains all, which is not very fair for QuickTime. The good practice is to use many small, evenly sized, audio samples that are indexed for fast and accurate random access.
Fortunately, there's a workaround: If you open the long audio file and just save it with a different name, QuickTime will rehash the audio media into small, evenly sized samples. And the problems are gone. This operation can be performed with QuickTime Pro or SimpleMovieX.
Repaired AAC files also tend to develop a specific pathology: Stutter