Tool comparison
A simpler untrunc alternative for repairing broken MP4 files
If you've searched for how to fix a truncated or unfinalized MP4, you've probably run into untrunc. It genuinely works — but it's a command-line tool you have to compile yourself, and that stops a lot of people in their tracks. This guide explains what untrunc does, when it's the right choice, and a drag-and-drop alternative that uses the same repair method.
What untrunc actually does
untrunc is a free, open-source tool that repairs MP4 and MOV files whose moov atom — the index a player needs to read the file — was never written. This is exactly what happens when a recorder like OBS crashes before finalizing a recording.
Its clever trick is using a reference file: a healthy video recorded with the same device and settings. Because that reference contains a correctly written moov atom, untrunc can use it as a template to rebuild the missing index in your broken file. The footage was never gone — it just had no map.
If you want the full explanation of why recordings corrupt this way, see our guide on fixing a corrupted OBS recording.
Where untrunc gets hard
The repair logic is solid; the friction is everything around it:
- You have to build it. There's no official installer for most platforms — you compile from source or hunt for an unofficial binary.
- It's command-line only. You pass the reference and broken file as terminal arguments, with no visual feedback.
- The GUI fork is unmaintained. The community
untrunc-guiexists but is difficult to get running on current systems. - No preview. You don't know whether the repair worked until you open the output and hope.
For a developer comfortable in a terminal, none of this is a dealbreaker. For a streamer who just wants their VOD back, it's a wall.
untrunc vs. StreamSalvage at a glance
| untrunc (CLI) | StreamSalvage |
|---|---|
| Compile from source | Download and run |
| Terminal commands | Drag and drop |
| No repair preview | Free preview before you pay |
| Manual reference setup | Guided 10-second reference clip |
| Local & private | Local & private |
| Free | $29 one-time to export |
Which one should you use?
Use untrunc if you're technical, comfortable building software, and don't mind the command line — it's free and it works.
Use StreamSalvage if you'd rather drop in your file, follow a guided prompt to record the reference clip, and see the repaired result before paying anything. It performs the same reference-based repair, stays 100% local so your footage never uploads, and skips the build-and-terminal steps entirely.
Same repair, no command line
Drop in your broken MP4, record a quick reference clip with the guided steps, and preview the repair for free. Pay $29 only if it works.
Download StreamSalvage for WindowsFrequently asked questions
What does untrunc do?
untrunc is a free, open-source tool that repairs truncated or unfinalized MP4 and MOV files. It uses a healthy reference video recorded with the same settings to rebuild the missing moov atom in a broken file, making it playable again.
Is there a GUI version of untrunc?
There is a community untrunc-gui project, but it can be hard to build and is no longer actively maintained for newer systems. If you want a maintained drag-and-drop experience, StreamSalvage performs the same reference-based repair with a graphical interface and a free preview.
Is untrunc safe to use?
untrunc runs locally and does not upload your files, which makes it safe from a privacy standpoint. The main hurdles are compiling it and using the command line correctly. StreamSalvage keeps the same local-only privacy while removing the build and terminal steps.
Do untrunc and StreamSalvage repair files the same way?
Both use the same core idea: a clean reference clip recorded with matching settings supplies the metadata needed to rebuild a broken MP4. StreamSalvage adds a free preview so you can confirm the repair worked before paying, and a guided workflow for recording the reference.