I used a program to capture my screen (called Kazam for linux). My computer crashed and I lost my screen capture which I cannot recreate.

I found two files that seem to hold my video, a .mux and .movie file. I tried using gstreamer or ffmpeg to convert the file bug this wouldn't work. From the Kazam source I saw that gstreamer is used to capture the video.

When I run tcprobe -i on the file name I get the following output:

[tcprobe] Digital Video (NTSC)
[tcprobe] summary for kazam_5bcdqb.movie.mux, (*) = not default, 0 = not detected
import frame size: -g 720x480 [720x576] (*)
     aspect ratio: 4:3 (*)
       frame rate: -f 29.970 [25.000] frc=4 (*)

Does anybody know how I can convert (using Linux) the mux file to a playable mp4 file?


  • 1
    Don't have an answer myself, but you might find that posting the mediainfo of the file is more useful for assistance as it usually contains more details. mediainfo.sourceforge.net/en FWIW there seems to be a related bug on launchpad which might be answered in the future answers.launchpad.net/kazam/+question/218308
    – James
    May 29 '13 at 20:32
  • Thanks for your tip, I got no information from media info. Just the file size. I already know of the launchpad question, I've contacted the original author but no luke so far. When Kazam finished a capturing gstream does "something" and the file is moved... If I only knew the gstream command (try searching in source, but I'm no python expert)
    – DanFritz
    May 29 '13 at 21:45

The same happened to me and I was able to restore the video, using a tiny and very easy tu use program: mp4fixer

Step 1: find the mux files

First (for someone else who is a step behind), you need to find the lost temp video files, with .mux extension. In your linux terminal, go to the root folder and type:

$ find . -type f -name "*.mux"

My files were located in my Videos folder:


Step 2: record a new sample video

Now, you need to generate with Kazam a new video of at least 20 seconds long, if possible similar to the one you are trying to recover:

Be sure to record it exactly under the same conditions, including even shaking on the screen (same bitrate), if it was - so we will find exactly what we are looking for. The length of the video is 20 seconds, but if you feed more - it's ok.

You will get a new video file, for example: goodvideo.mp4

Step 3: download mp4fixer

Go to mp4fixer Github page and download the zip file (there is a green dropdown button on the top-right section of the screen).

Save the file somewhere in your disk and unzip it.

Copy the mux files and the sample mp4 file into the same folder.

Step 3: run the program

In the terminal, go to the folder where you unzipped the program and you copied the video files, and run:

$ perl fixer.pl goodvideo.mp4 kazam_mv84r5fr.movie.mux recovered

When the program finishes, you will see some new files in the folder:

recovered-out-audio.raw  <-- AUDIO
recovered-out-video.h264 <-- VIDEO

Step 4: convert to mp4

The last step is to convert the recovered video from .h264 to .mp4, and to include the audio in it.

I did it using the ffmpeg utility (install it first):

$ ffmpeg -i "recovered-out-video.h264" -i "recovered-out-audio.raw" -c:v copy -c:a copy -f mp4 "recovered-video.mp4"

A recovered-video.mp4 working video file will be created in the folder. It worked for me, I hope it works for you as well.

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