About Untrunc
The story behind an open-source video repair tool trusted by videographers, drone pilots, and IT professionals worldwide.
The History of Untrunc
Untrunc has an interesting origin. It was created as a practical research tool by someone who needed to solve a real problem – and it grew into one of the most relied-upon free video repair utilities available today.
The Original Project
Federico Ponchio, a researcher at CNR ISTI (the National Research Council of Italy), released the original Untrunc on GitHub. The tool was designed to address a surprisingly common problem: video files that recorded fine but became unplayable because the moov atom – the file’s index – was never written due to an abrupt shutdown.
Community Adoption
Videographers, GoPro users, and IT professionals discovered Untrunc and it spread through forums, Reddit communities, and tech support threads. The open-source GPL-2.0 license meant anyone could inspect, modify, and improve the code.
The anthwlock Fork Takes Over
Developer anthwlock created a heavily improved fork of Untrunc. This version introduced significant performance improvements – roughly 10x faster than the original – along with better support for GoPro footage, Sony XAVC, files over 2GB, and audio-video sync correction. Pre-built Windows binaries made it accessible to users who could not compile from source.
The Go-To Free Video Repair Tool
Untrunc remains the most recommended free solution for corrupted MP4 and MOV repair on forums like Reddit’s r/videography, r/gopro, r/dashcams, and DJI user communities. Multiple platform distributions followed, including Docker images, Linux package manager builds, and macOS Homebrew formulas.
What Untrunc Does
At its core, Untrunc works by reading the structure of a healthy reference video recorded with the same device and settings, then using that structure to rebuild the missing or corrupted index of the damaged file. The approach is clever because it does not try to blindly reconstruct missing video data – it uses real metadata from an actual working file.
The typical use case is simple: you provide a working reference video from the same camera and same settings, then run Untrunc with the reference file and broken file as arguments. The output is a repaired file named broken_fixed.mp4.
The Developers Behind Untrunc
Federico Ponchio created the original Untrunc in 2013. Ponchio is a researcher at CNR ISTI, the Visual Computing Lab of Italy’s National Research Council, with a background in computer graphics, geometry processing, and multimedia. Untrunc was a practical utility that solved a real problem he and his collaborators encountered.
anthwlock is the primary maintainer of the most widely used fork. Their work turned Untrunc from a functional research tool into a polished, high-performance utility with broader format support, Windows binary releases, and significant speed improvements. The fork is hosted at github.com/anthwlock/untrunc and is what most users rely on today.
Other contributors have created additional forks and distributions, including Linux AUR packages, Docker images, and GUI wrappers – all building on the foundation of open-source collaboration under the GPL-2.0 license.
Who Uses Untrunc
Untrunc has become an essential rescue tool for a wide range of users:
- GoPro and action camera users – Recovering footage from cameras that ran out of battery mid-recording
- Drone pilots – Repairing DJI footage from flights that ended in a crash or signal loss
- Dashcam owners – Restoring dashcam video cut short by a power issue or collision
- Screen recorders – Fixing OBS or other recording software outputs interrupted by crashes
- Security camera operators – Recovering surveillance footage from power failures
- Videographers and filmmakers – Rescuing professional footage from card or device failures
Across Reddit communities for GoPro, DJI, dashcams, and videography, Untrunc is consistently the first recommendation when someone reports a corrupted video file. Its status as free, open-source software makes it stand apart from expensive paid alternatives like Grau GmbH Video Repair Tool or Stellar Repair for Video.
About This Website
untrunc.com is an independent, fan-made informational resource. We built this site to help users find clear, accurate information about Untrunc – how it works, how to use it, and where to download it safely.
This website is not affiliated with, endorsed by, or officially associated with Federico Ponchio, anthwlock, or any other developer of the Untrunc project. We are an independent resource. All download links on this site point to official sources – we do not host or modify any software files.
Our mission is straightforward: help users discover and successfully use Untrunc. We link only to official GitHub release downloads and encourage users to check the official repository for the latest versions and changelogs. We deeply respect the work of the developers who built this tool and shared it freely under an open-source license.
For official software information, issues, or contributions, visit github.com/anthwlock/untrunc.
Contact
Have feedback about this website, found an error, or want to reach out? Use our Contact page. We read every message and appreciate corrections and suggestions.
For technical support with the Untrunc software itself, please open an issue on the official GitHub repository. We are not able to provide software support.