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Restoring damaged clips with untrunc
Restoring damaged clips with untrunc
Ben Hagen avatar
Written by Ben Hagen
Updated over a week ago

This guide describes the installation and usage of the open source tool untrunc which is used to Restore a damaged (truncated) mp4, m4v, mov or 3gp video. This is especially useful to rescue .RSV files written by a Sony camera.

NOTE: Restoring in camera is prefered if it is supported by your camera model. Please also read the full article on .RSV files.


  • Install the homebrew package manager if you are not already using it:

    /bin/bash -c "$(curl -fsSL"
  • Enable the OTTOMATIC tap

    brew tap ottomatic-io/video
  • Install the untrunc package

    brew install untrunc


To restore a clip, you need a donor file which has the same recording settings. Most often that is the clip you shot before.


untrunc /path/to/C1001.MP4 /path/to/C1002.RSV

This will create a file called /path/to/C1002.RSV_fixed.mp4.

If you see an error like "Error: unable to find correct codec -> premature end (~0%)", please try to use the -s option to step through unknown sequences:

untrunc -s /path/to/C1001.MP4 /path/to/C1002.RSV

NOTE: If it is not working, please do not hesitate to reach out to our support!

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