Playing Detective: Repair a corrupt movie to identify a thief

I have started Movie Repair as a business in July 2007 and I no longer repair movies for free.

A few months ago, I read a forum post about a school teacher requesting help to identify the thief of a computer in the classroom during the night. It turns out that a webcam was hooked to the Mac mini, which recorded the theft to an external hard disk.
The Mac was stolen, but the hard disk, inside a locked enclosure, was left behind.
Unfortunately, as the recording was interrupted abruptly, the movie file was corrupt and could not be open.

I knew that in such cases, the video data was probably intact, but as the table of content and structure of movie was missing, it could not be accessed. At least not without some hacking…
I felt really excited by the prospect of repairing a file that would reveal a crime. I finally offered some assistance to the teacher. He sent me the file, and it took me a few hours to find out a way to repair it. First I managed to decode one frame. Then another.
It involved some byte hacking, using an hexeditor and writing a short program to extract some information. I also had to record a placeholder movie with exactly the same settings as the corrupt one. I transferred the video data to the placeholder, and, like magic, the movie was suddenly readable.

The movie shows how the teacher turns on the webcam before leaving, switches the lights off, then it’s completly dark in the classroom. The webcam software only records when there is some movement, so the next scene directly depicts the theft. You see a shadow approaching, holding a lamp. The lamp moves in front of the camera as the thief opens the cabinet and takes the computer, but unfortunately you never see his or her face, and suddenly the movie ends.

Too bad, the movie would not reveal the identity of the thief.
But I felt I had stumbled upon something. Every day, hundreds of corrupt QuickTime movies are “produced”. And I can probably repair most of them.

I want your corrupt Quicktime movies.
Stuff happens. After hours of rendering, the spinning ball of death appears and your favorite application goes west. You’ve just lost your work and you’ll miss that important deadline. If ever you could get it repaired!
As the process was interrupted abruptly, the half-baked QuickTime movie file cannot be open.
You know it contains the video and the audio, mostly intact, with maybe a few corrupt frames, but as the table of content and the structure of the movie is missing or uncomplete, there’s no way to repair it.

Or at least until today.
I’m trying to develop a software or a service, or a mix of both, that will repair QuickTime files.
At this stage, I’m just learning the most efficient techniques to repair QuickTime movies, that’s why I need to collect many corrupt movies. I will work for fun and for free. I don’t guarantee success either, sometimes it’s just not possible.

If you have such a file, please contact with me by email: info at

1 Comment

DizzieJune 13th, 2007 at 2:57 pm

Nice blog. Thanks! I’ll let you know if I get any corrupt files!