How to fix a corrupted video file on a Mac

Find out which failure you have

Drop the file in below. It reads the structure in your browser and tells you which of these you are looking at. Nothing is uploaded, it works on any computer, and it takes seconds.

The three things “corrupted” usually means

1. The recording was never finished

Much the most common, and the most recoverable. A camera writes video to the card as it records, but the index that says where every frame lives is written last, when you press stop. A flat battery, a pulled card, a crash or a full card means the footage is all there and the index never got written.

The file is the right size and nothing opens it. Players say moov atom not found, or Invalid data found when processing input, or fail without saying anything at all.

This one is fixable. The frames can be found again and a new index written. See what that error actually means, or, if you know it was a flat battery or a pulled card, what a power cut leaves behind.

2. The file is there but the data is not

A file of a few kilobytes, or one that reports a length of zero. The camera created the file and never wrote the recording into it, or the card failed before anything reached it.

Nothing that works on the file itself can help, because there is nothing inside it to rebuild. The remaining route is card‑level recovery software that scans the raw card for orphaned data, ignoring the filesystem. Stop using that card immediately if you go that way.

3. The file is complete but your player will not decode it

The file has its index and plays elsewhere, or plays sound with no picture, or opens in one application and not another. That is a codec problem rather than damage, and rebuilding anything would not help.

Try VLC first: it opens a great deal that QuickTime refuses, and if it plays there the file is fine and the problem is the player.

Checking it yourself in the terminal

If you would rather look directly, the first bytes of the file name its top level boxes:

xxd -l 64 broken.mp4

A healthy MP4 or MOV contains ftyp, mdat and moov. Seeing ftyp and mdat with no moov anywhere in the file is failure 1 exactly. With ffmpeg installed:

ffprobe -v error -show_entries format=duration -of csv broken.mp4

A file whose duration cannot be read, but whose size is what you expect for the length you shot, is the same story.

What actually rebuilds it

Cinesalve is a Mac app for failure 1. It finds the frames in the media and writes the index the camera never got to, so the recording plays again. On the GoPro models measured, H.264 and HEVC alike, it needs nothing but the damaged file; recordings that do not state their own settings ask for any clip from the same camera that plays.

Recovery is measured against the original, frame by frame: a frame counts only when it lands at the same byte offset and the same size the camera wrote.

Steps written for a particular camera, where the free things to try first differ: GoPro, DJI, Canon, iPhone, Sony, OBS.

Still stuck

Describe the camera and what happened to cinesalve@proton.me (or the contact form) and you will get a straight answer, including when the answer is that the footage is gone.