How to fix a corrupted video with green blocks, gray smears or frozen pixels

What causes it

• Interrupted transfers, a flaky SD card or USB cable, or a download that was cut off.
• Camera power loss while recording, which leaves the file without its index.
• Packet loss in streams and recordings.
• Bit rot or damaged storage.

What repair can do

Video is stored as periodic full frames and many frames that only describe the changes. If one is damaged, errors spread until the next full frame. Repair tools can skip bad packets, rebuild the container and re-encode the survivors, which removes the worst smears. They cannot recreate missing sections.

If the file has no moov atom (an MP4 that never finished writing), the index that says where each frame is stored is gone. Specialist tools such as untrunc can sometimes rebuild it with the help of a healthy file from the same camera. Otherwise it is lost.

Recover a corrupted video

1. Copy the file againRe-copy from the card or source to rule out a bad transfer, and compare file sizes.
2. Upload it to the fixerIt tries several repair strategies automatically: error-tolerant remux, salvage re-encode and raw stream extraction.
3. Read the resultYou will see whether the repair worked and a preview of the recovered footage.
4. For unfinished recordingsUse a reference clip from the same camera and a tool such as untrunc if the file has no index.