Repair Video – Fix Corrupted or Unplayable MP4, MOV & MKV
Repair video files that will not open, show the wrong length, freeze when you seek or drift out of sync. Often the picture data is fine and only the container or its timestamps are damaged, which ProMedia can rebuild in your browser. Quick fix copies the streams into a fresh file; Deep repair re-encodes whatever is still readable. Your footage is never uploaded.
- Runs on your device
- WebCodecs · GPU
- FFmpeg
- Works offline
Updated
Drop your videos here
How to repair a video
Step 1: Drop the broken MP4, MOV, MKV, WebM or other video on the box above.
Step 2: Start with Quick fix. It rebuilds the container without touching the picture.
Step 3: Press Repair, then play the new file to check it.
Step 4: Still broken, out of sync or freezing? Run it again with Deep repair.
Good to know
Settings explained
- Repair
- Quick fix: Rebuild container and index
- Deep repair: Re-encode what is readable, with fresh timestamps
Formats
Batch-friendly: add many files and they are processed one after another — if one fails, the rest still finish.
How it runs
- Hardware video engine
- Video is decoded and encoded by your device’s media hardware through WebCodecs — usually several times faster than real time.
- FFmpeg (when needed)
- Older formats and a few filters use FFmpeg compiled to WebAssembly. It downloads once (about 31 MB) the first time it is needed and is cached for offline use.
What this video repair tool can fix
Repair works when the video data is still in the file but the structure around it is broken. It cannot bring back data that was never written, such as the end of a recording cut off by a dead battery. The table maps common symptoms to the mode that helps.
| Symptom | Try | Can it be fixed? |
|---|---|---|
| Will not open, “file not supported”, but the size looks right | Quick fix | Often |
| Shows no length or 0:00, cannot seek (common with browser recordings) | Quick fix | Yes |
| Audio drifts out of sync, stutters or freezes partway | Deep repair | Often |
| Grey or green blocks after a damaged section | Deep repair | Partly: damaged frames are hidden or skipped, not restored |
| Recording cut off before it finished (phone died, card pulled) | — | No: the index (“moov atom”) was never written |
| Plays sideways | Not a repair job | Use rotate video instead |
Quick fix vs Deep repair: what each one does
Both modes run on your device. Try the fast, lossless one first and only move on if the result still misbehaves.
Quick fix
Reads every packet and writes them into a brand-new container, which rebuilds the index, the duration and the seek points. If that fails, FFmpeg tries again, regenerating timestamps and dropping corrupt packets. MOV, MKV and WebM stay in their format; when the original codecs will not fit, the file is saved as MKV. The picture is not re-encoded; only audio that the rebuilt container cannot hold is converted, and the result card says so.
Deep repair
Decodes the video with error concealment, skips damaged frames, lays everything on a clean constant frame rate and resyncs the audio to it. The result is a fresh H.264 + AAC MP4 at high quality (x264 CRF 20, 160 kbps audio). Use it for stutter, freezes and sync drift.
Can a corrupted video file be fixed?
Usually, if the video data is there. Most “corrupted” files have a damaged container, a missing duration or broken timestamps, and those can be rebuilt. What cannot be fixed is data that was never saved: when a phone or camera stops recording abruptly, the MP4 or MOV may lack its index, the “moov atom” that says where every frame is. Rebuilding that needs a reference video from the same camera, which this tool does not support yet; it tells you when that is the problem.
How to fix a corrupted video on Windows, iPhone or Android
Windows
Drag the file into Chrome, Edge or Firefox here. If Windows’ own player shows a codec error rather than a damage error, the file may be fine and just HEVC; try HEVC to H.264.
iPhone
Save the video to Files, open this page in Safari and tap the drop zone. Save the repaired file back to Files and test it in Photos.
Android
Open the page in Chrome, tap the drop zone and pick the file from your gallery or downloads. The repaired copy lands in Downloads; the original is never changed.
Why repair videos here
- Private footage stays private. Damaged files are often personal recordings. Repair runs in your browser, so nothing is uploaded to a recovery service.
- Free, with no preview trap. You get the whole repaired file, not a watermarked sample with a price tag.
- The original is untouched. Every repair writes a new file, so you can try both modes safely.
Tips & troubleshooting
To repair an MP4 file from a dashcam or a MOV file from an iPhone, start from the original, not a copy a messaging app has already re-compressed.
Screen or browser recording with no length? Quick fix rebuilds the missing duration in seconds.
Repaired but in the wrong format for your editor? Run it through the video converter afterwards.
If the file plays but a codec error appears in one app only, it is not damaged; check the codec with Media Info.
Repair Video FAQ
How do I fix a corrupted video file?
Drop it on this page and run Quick fix, which rebuilds the container and index without re-encoding. If the new file still freezes, stutters or drifts out of sync, run Deep repair, which re-encodes everything that is still readable on a clean timeline.
How do I fix a corrupted MP4 video?
Start with Quick fix: most broken MP4s have a damaged index or odd timestamps, which a fresh container fixes losslessly. If the MP4 was cut off before recording finished, its index is missing, and that cannot be rebuilt here.
Can a truncated MP4 without a moov atom be repaired?
Not with this tool. The moov atom is the index that tells a player where each frame is; without it, rebuilding needs a reference video from the same camera and settings, which ProMedia does not support yet. It says so instead of producing a broken file.
Why won’t my video play?
Either the player does not support its format or codec, or the file is damaged. If it plays elsewhere, convert it with the video converter. If it fails everywhere, shows no length or stops early, repair it here.
How do I fix a video that stops halfway?
Run Deep repair. It skips damaged packets and keeps decoding the rest, so the video continues past the bad section. If the recording itself ended there, there is nothing after that point to recover.
Will repairing change the quality?
Quick fix copies the video without re-encoding, so the picture is identical; only audio that cannot go into the rebuilt file is converted. Deep repair re-encodes to H.264 + AAC at high quality, so expect a small change; damaged frames are hidden rather than restored.
Is your video uploaded anywhere?
No. Your video is processed by your own browser on your own device. There is no server that receives files, so nothing is uploaded, stored or shared. You can even switch to airplane mode once the page has loaded.