Untrunc review
A focused, free tool for technical users repairing truncated MPEG-4 containers locally.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Untrunc is a free, open-source utility for repairing truncated or damaged MPEG-4 container files. It is intended for technically comfortable users working with MP4, MOV, M4V, and 3GP files on Windows, macOS, or Linux. Repair runs locally and creates a repaired output file without modifying the original. The project offers a command-line workflow, an optional Windows graphical interface, and Docker support for container-based use.
Its standout feature is reference-video reconstruction. Untrunc uses a healthy recording to rebuild missing video metadata, preferably from the same camera and recording mode as the damaged file. The tool also supports files larger than 2 GB, advanced logging for troubleshooting, and options for skipping unknown bytes or adjusting audio-video duration. These controls give experienced users more room to investigate difficult repairs than a basic point-and-click utility.
Untrunc is a narrow file-repair tool rather than a broad media-recovery suite. Its local delivery, open-source model, command-line interface, and cross-platform support suit users who are comfortable selecting a reference recording and working through repair options. Choose it when the affected file matches its supported container formats and you can provide a suitable healthy video. Users seeking wider format coverage or a primarily guided graphical workflow should consider a different type of repair utility.
Untrunc pros and cons
- Where it wins
- Repairs MP4, MOV, M4V, and 3GP containers
- Uses a healthy reference video to reconstruct missing metadata
- Free, open-source, cross-platform, and supports files over 2 GB
- Where it doesn't
- The repair workflow depends on a healthy reference video
- Its focus is limited to specific MPEG-4 container formats
- The graphical interface is optional and available for Windows
Untrunc fact sheet, pricing and score →
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