By Pritibhukhan Borah, Computer Science Engineer · Last updated: 2026-11-02
Signs a video may be corrupted
- No player will open it, or it opens with an error message
- The length shows 0:00 or is far shorter than the recording
- The file stops partway, freezes, or shows blocks and green frames
- The file size is very different from what you expect for that recording
Test 1: Compare the file size with what you expect
Recording data takes space. A recording that ran for ten minutes at 1080p is normally hundreds of megabytes. If the file is only a few kilobytes, the video data was probably never written and there is little to repair. If the file is roughly the right size but will not open, the footage is usually there and only the index at the end of the file is missing or damaged, which is the repairable case.
Test 2: Try a second player and a second computer
Open the file in VLC as well as your system player. Some "corrupted" videos are only using a codec that one player does not support. If VLC plays it, your file is fine and you need a different player or a converter, not a repair.
Test 3: Ask ffprobe what it sees
ffprobe comes with FFmpeg and reads the file header without playing it. Run:
ffprobe -v error -show_format -show_streams video.mp4If it prints the streams, codec and duration, the index is readable. If it prints moov atom not found, the MP4 or MOV index is missing (see what that error means). Invalid data found when processing input means the beginning of the file could not be understood at all.
Test 4: Decode the whole file and list the errors
This reads every frame without saving anything:
ffmpeg -v error -i video.mp4 -f null -No output means every frame decoded cleanly. A handful of errors near one timestamp point to local damage, so most of the video can still be recovered. Errors that start immediately and never stop point to a damaged header or a missing index.
Test 5: Rule out a bad copy
Many files are fine at the source and damaged by an interrupted copy, download or sync. Compare checksums of the original and the copy:
- Windows:
certutil -hashfile video.mp4 SHA256 - macOS:
shasum -a 256 video.mp4 - Linux:
sha256sum video.mp4
If the values differ, copy the file again before doing anything else.
How to read the results
| What you see | Likely meaning | Next step |
|---|---|---|
| "moov atom not found" | MP4 or MOV index missing | Repair with a reference video |
| Plays in VLC, not in another player | Codec or compatibility problem | Use VLC or convert the file |
| Errors at one point only | Damaged data in the middle | Repair what is intact; that spot may glitch |
| Copy checksum differs from original | Bad transfer | Copy again from the source |
| File is tiny for the recording length | Footage was never written | Little can be recovered |
Whatever you find, keep the original file untouched and work on a copy.
Related
Frequently asked questions
Can I check a video without installing any software?
Yes. File size and a second player such as VLC (which is free) cover the most common cases. ffprobe and ffmpeg give more detail but are optional.
Does an ffmpeg error always mean the video is unrecoverable?
No. Many errors come from a missing index rather than missing footage. The position of the first error and the file size help tell the two apart.