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Untrunc
What it is
Untrunc is free software that repairs corrupted or truncated MPEG-4 video files using a healthy reference video to reconstruct missing or damaged index metadata. It rebuilds file structure without re-encoding or changing raw media data. Supported containers are MP4, MOV, M4V, and 3GP, and the reference video should come from the same camera and use the same recording settings as the damaged file. Repairs run offline on local files, with no video uploads or telemetry. The software has no file-size limit and can process files larger than available RAM using streaming mode. It is available for Windows, macOS, and Linux, including self-hosted use. Windows downloads include both a command-line tool and a graphical interface; the site describes command-line use for other platforms. The site describes support for GoPro footage and Sony XAVC, and says the anthwlock fork adds compatibility and performance improvements. An optional stretch mode can adjust audio duration to match the recovered video. Untrunc is open source under GPL-2.0 and free for personal and commercial use. It cannot recover empty files, damaged raw video data, or non-MPEG-4 containers such as AVI and MKV.
For and against
For
- Repairs run locally without uploads or telemetry.
- No file-size limit; streaming mode handles files larger than RAM.
- Windows download includes a graphical interface and command-line tool.
- Free for personal and commercial use under GPL-2.0.
- Supports MP4, MOV, M4V, and 3GP.
Against
- A healthy reference video from the same camera is required.
- Cannot recover empty files or damaged raw video data.
- Does not support AVI or MKV containers.
- Technical support is directed to the anthwlock GitHub Issues page.
The verdict
Untrunc provides local repair for supported MPEG-4 containers without re-encoding, provided you have a suitable reference clip. It cannot fix empty files, damaged raw video data, or non-MPEG-4 containers.
Who it suits
Untrunc may suit action-camera users, drone pilots, dashcam owners, screen recorders, security-camera operators, and videographers dealing with damaged supported video files.
Plans and prices
Free
No usage or file-size limits · GPL-2.0 · Requires a healthy reference video from the same camera and recording settings
Read 9 Oct 2026 · untrunc.com
On the record
- Audio sync
- An optional stretch mode can adjust audio duration to match the recovered video track.untrunc.com · read 9 Oct 2026
- Camera compatibility
- The site describes support for GoPro footage and Sony XAVC, with the anthwlock fork adding compatibility and performance improvements.untrunc.com · read 9 Oct 2026
- File-size limit
- The site says Untrunc has no file-size limit and can process files larger than available RAM using streaming mode.untrunc.com · read 9 Oct 2026
- Intended users
- The site names action-camera users, drone pilots, dashcam owners, screen recorders, security-camera operators, and videographers as users.untrunc.com · read 9 Oct 2026
- Interfaces
- The Windows download includes a command-line tool and a graphical interface; the site also describes a command-line workflow for other platforms.untrunc.com · read 9 Oct 2026
- License
- The software is described as open source under the GPL-2.0 license and free for personal and commercial use.untrunc.com · read 9 Oct 2026
- Limitations
- The site says Untrunc cannot recover empty files, raw video data that is itself corrupted, or non-MPEG-4 containers such as AVI and MKV.untrunc.com · read 9 Oct 2026
- Privacy
- The site says repairs run offline on local files, with no video uploads or telemetry.untrunc.com · read 9 Oct 2026
- Purpose
- Untrunc repairs corrupted or truncated MPEG-4 video files by using a healthy reference video to reconstruct missing or damaged index metadata.untrunc.com · read 9 Oct 2026
- Reference requirement
- The reference video should come from the same camera and use the same recording settings as the damaged file.untrunc.com · read 9 Oct 2026
- Repair method
- It rebuilds the file structure without re-encoding or modifying the raw media data.untrunc.com · read 9 Oct 2026
- Support
- The site directs users to the anthwlock GitHub Issues page for technical support and says the informational website does not provide software support.untrunc.com · read 9 Oct 2026
- Supported formats
- The site lists MP4, MOV, M4V, and 3GP as supported container formats.untrunc.com · read 9 Oct 2026
