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About Untrunc

The open-source repair engine behind rsv.repair, and the people who built it.

rsv.repair is powered by Untrunc, an open-source tool that restores damaged or truncated MP4, M4V, MOV, and 3GP video files. Given a working reference video from the same camera, Untrunc can rebuild the container structure so the file plays again.

The web app is built on a work-in-progress branch that adds Sony .rsv recovery support and compiles Untrunc to run in the browser. That branch builds on the anthwlock/untrunc fork, which itself improves on the original by ponchio.

anthwlock/untrunc brought major improvements over the original by ponchio:

  • More than 10x faster
  • Low memory usage
  • >2 GB file support
  • Ability to skip over unknown bytes
  • Generic support for all tracks with fixed-width chunks
  • Can stretch/shrink video to match audio duration
  • Compatible with newer versions of FFmpeg
  • Handles invalid atom lengths
  • Supports GoPro and Sony XAVC videos
  • Many bug fixes

The web branch builds on anthwlock’s work and adds:

  • Sony RSV file recovery (H.264 and H.265)
  • Browser-based execution (compiled to run in your browser; no install needed)

This project would not exist without the work of the open-source community:

  • ponchio created the original Untrunc.
  • anthwlock rebuilt and maintained the improved fork that most people use today.
  • cbenhagen improved RSV recovery and implemented the browser port.
  • FFmpeg provides the audio/video libraries that Untrunc depends on.

If this software helped you, please consider donating to the people who wrote the repair engine.

Thank you for supporting open-source software.