Repair a corrupted video file
When a camera loses power or the card is pulled mid-recording, the footage is usually still there, but the index that tells a player where each frame is was never written, so nothing will open the file. Drop the broken file and a good clip from the same camera with the same settings: we find every frame and every bit of sound in the broken file and write a new index. The file never leaves your computer, so a multi-gigabyte card dump is fine.
How to use it
- Drop the broken fileThe MP4 or MOV that will not open.
- Drop a good clipAny clip that plays, from the same camera with the same settings.
- Rebuild itEvery frame and sound frame is found and a new index is written.
- Check and saveWatch the preview, then download the repaired copy.
What you can download here
- Repaired videothe same MP4 or MOV, picture and sound untouched, with a new index
Good to know
Copy the files off the card before trying anything, and don't record on that card again until the footage is safe: a card that corrupts clips again and again should be replaced.
Cuescribe for Chrome
A transcript side panel on every YouTube and TikTok video, a library of everything you transcribe, and one click to open any of it in these tools.
Pro keeps this free
Every tool stays free. Pro (early access, $5/month or $39/year) adds batch delivery with client presets and file naming, editor timelines, multi-camera sync, the extension's Pro features and 200 credits every month. Early subscribers keep their price and choose what gets built next.
What Pro includesNext steps
Questions
Which files can it fix?
MP4 and MOV recordings that stopped suddenly: the battery died, the card was pulled or full, the camera or phone crashed, the app was closed mid-recording. Those files have the picture and sound but no index (the "moov"), which is why players say the file is damaged or unsupported. The video must be H.264 or H.265 (HEVC), with AAC or uncompressed (PCM) sound, which is what most phones and many cameras record.
Why does it need a good clip?
The broken file has lost the part that describes how it was recorded: the codec settings, the frame rate and the sound format. A clip that plays, recorded on the same camera with the same resolution, frame rate and quality setting, has exactly that. A few seconds is enough; its own picture is not used.
What can it not fix?
It rebuilds a missing index; it cannot repair damaged picture data. If parts of the file were overwritten or the card has bad blocks, those frames stay lost (the page says how much was not recognised), and glitches inside a frame stay as they are. Timecode and other camera data tracks are left out; the picture and sound are kept.
The start of my file was damaged. What happens?
The picture can only start at the first whole keyframe, so a damaged start loses a little picture. The sound is kept from where it was found, and the picture is placed at the time worked out from it, so they stay in sync (it may be a frame or so off).
Is my footage uploaded?
No. Both files are read in this tab, a piece at a time, so there is no size cap and a 4K file of several gigabytes works. The repaired copy is the new index followed by your original data, saved as a new file; your original is not changed.
How is this different from the paid repair apps?
Many "video repair" apps rebuild the index from a sample file in the same way (the free command-line tool untrunc does too), then charge for the result, cap the free size, or need the file uploaded. This one is free, has no cap, and runs on your computer.