Repair a corrupted MP4 video
Fix corrupted MP4/MOV videos in your browser: rebuilds the box structure, clamps truncated data and restores a playable file. Free, never uploaded.
Drop the damaged video here
or click to choose — MP4/MOV structure rebuilt on your device, never uploaded
Rebuilding in your browser…
Walking the box structure — nothing uploaded
When a player says a video “can’t be opened”, the picture and sound are usually still there — what broke is the box structure: the indexed containers (moov, mdat) that tell the player where everything is. Downloads that stop halfway, crashed recordings and botched transfers all damage these boxes.
Drop the video here: Rollphy walks the raw bytes, resynchronizes at every recognizable box, clamps data boxes that claim more bytes than survived, synthesizes a missing file-type header, and repacks a clean, self-consistent MP4. The whole scan runs in your browser — gigabyte videos never leave your device.
Honest limits: if the moov index (usually written last) was the part that got cut off, the playback index is gone and no tool can rebuild it from the file alone — that family of recovery needs a reference recording from the same device. This tool detects that case and tells you plainly instead of returning a file that pretends to work.
Frequently asked questions
- The video plays for a few seconds then stops — fixable?
- Often yes: that pattern is a truncated data box. Clamping its declared size gives players a self-consistent file that plays everything that survived.
- Does repairing re-encode my video?
- No. The repair only rebuilds container structure around the compressed media — audio and video data are byte-for-byte untouched.
- “moov atom not found” — can you fix that?
- It depends where the moov index was. If it survived in your file, the rebuild keeps it and the video plays. If the recording was cut before the index was written, the index is genuinely gone — the tool will tell you that case honestly.