Video corrupted after copying or transferring? Check this first
By the FixMP4 engineering team · · 6 min read
A common story: the video played perfectly on the phone or camera, but the copy on the computer will not open, stops halfway, or shows 0:00. Before repairing anything, remember that the original may still be fine. Copies fail in a few predictable ways.
Compare the sizes exactly
Look at the size in bytes, not the rounded MB figure. On Windows, File Properties shows "Size: ... bytes"; on Mac, Get Info. If the copy is smaller than the original, the transfer was cut short. Copy again.
Typical causes
| Cause | What happens |
|---|---|
| Cable disconnected or loose | Copy stops partway |
| Phone over MTP (Android, iPhone on Windows) | Large files sometimes fail silently |
| Cloud placeholders (iCloud, OneDrive, Google Drive) | File shows but is not downloaded |
| FAT32 USB stick | Files over 4 GB cannot be stored; the copy fails or is truncated |
| Messaging and email | Compressed or size-limited copies |
| Sleeping laptop during copy | Transfer aborted |
| Failing USB stick or drive | Corrupted copies |
Better ways to copy
- Use a card reader rather than connecting a camera over USB.
- iPhone to Mac: Image Capture or AirDrop; to Windows, the Photos app import or File Explorer, with Settings, Photos, Transfer to Mac or PC set to Keep Originals.
- Android: USB File transfer mode, or a dedicated transfer app; check sizes afterwards.
- For big files, use exFAT or NTFS/APFS drives, not FAT32.
Verify important copies
Play the copy to the end, or compare checksums:
- Mac / Linux: shasum -a 256 file.mp4
- Windows: certutil -hashfile file.mp4 SHA256
Matching checksums mean identical files. Professional offload tools do this automatically.
When the original is gone
If you already formatted the card or deleted the original, the truncated copy is all you have. It contains the frames that made it across but, because the index is at the end of the original, usually no index. That is repairable:
- Make a short reference recording on the same device with the same settings.
- Open the repair tool, add the truncated copy and the reference.
- Check the free preview. You recover the portion that was copied.
If the original card was formatted recently and not reused, data recovery may also find the full original; see recover video from a corrupted SD card.
Downloads from the web or a cloud
An interrupted download can leave a partial MP4. Download it again. If the source is gone, the same repair approach applies when the file has its frames but no index. If the index is at the front (fast start files from the web) and the end is missing, players may play up to the cut; see MP4 fast start explained.
Signs a copy is incomplete
- The copy is smaller than the original by any amount.
- The copy plays but stops early, while the original plays to the end.
- The copy shows 0:00 but has a large size (common when the index sat at the end of the original and never arrived).
- Copying reported an error that was easy to miss, such as a notification that disappeared.
If any of these apply and the original still exists, copying again with a card reader or a cable you trust is faster and better than any repair.
Summary
A broken copy usually means a broken transfer, not a broken video. Compare sizes, copy again from the original, and verify. Repair only when the original is gone, and then you can recover what was copied.
Frequently asked questions
Why is my video corrupted after copying it?
The copy was interrupted or incomplete: a disconnected cable, an MTP transfer error, a cloud placeholder, or a 4 GB FAT32 limit. The original is usually still fine.
How do I verify a copied video?
Compare file sizes exactly, play the copy to the end, or compare checksums (for example with shasum on Mac or certutil on Windows).
What if the original is gone?
If the copy is truncated, rebuild its index from the frames that were copied; you recover the portion that made it across.
Have a broken recording right now?
Diagnose it and hear or watch a free repaired preview. Nothing is uploaded.
Open the repair tool