In short
- What happened: the recording was cut off before the camera wrote the map that tells a player where each frame sits, or the file arrived incomplete from a transfer that stopped halfway.
- What not to do right now: don't format the card, don't keep shooting on it, and don't convert the file. A converter can't read what VLC can't read.
- What to do: check the size matches the original, then build a new map with a healthy clip and a free program. Steps below.
- Don't want to deal with it? Send me the file. The check is free, and if I couldn't recover it, you get your money back. How to send it.
First: is the file complete?
There are two ways a file ends up without a map, and only one of them can be repaired.
- The file came straight off the card: the recording was cut off, the footage is inside. Go to the steps below.
- The file came by download, WeTransfer, Drive or a copy: compare its size with the original. Smaller? The transfer broke off, no repair will help, ask for the file again. Full size? Go to the steps below.
What to do, step by step
- Copy everything to the computer. The broken file, and while you're at it a healthy clip from the same card. From now on work only on the copies. The card stays aside.
- Prepare a “sample clip”. A healthy recording from the same camera at exactly the settings the broken file was shot with: same resolution (4K, say), same frames per second (25, 50 or 100), same recording quality. Simplest: a clip you shot the same day, just before or after the broken one, without changing settings in between. The clip you copied from the card usually fits. If there isn't one, put a card in the camera, lens cap on, and record 30 seconds.
- Run a free program called untrunc. It takes the map from the healthy clip and builds a new one for the broken file. Download it here (Windows. A normal program with buttons, nothing to type). On the page that opens, download untrunc_x64.zip, unzip it, and run untrunc-gui.exe (not untrunc.exe, which is the version without the window). Pick the sample clip, pick the broken file, and run. If the file that comes out won't open, run it once more, that happens. How you know it worked: a new MP4 appears, and it opens in a player.
- Check the whole file, not just the start. The length should match what you shot. Scrub to five or six points along the video, especially near the end. At each one stop, play a few seconds, and check the picture moves smoothly and the lips match the speech. If the picture jumps or the sound drifts: the sample clip doesn't match closely enough. Find a closer match and run again. Don't switch programs.
Why it happened
Every MP4 or MOV carries a small map that says how long the video is and where each frame sits. The camera writes it last, only when the recording ends cleanly. If the camera shut down, the battery died or the card was pulled first, the map was never written. VLC opens the file, finds no map, and can't even tell what it's looking at. Renaming the file or changing the extension doesn't add the map.
Shooting Sony?
If the file ends in .RSV rather than .MP4, it's exactly the same situation with a Sony name on it: what an .RSV file is and how to open it.
Short answers
- Is this a codec problem? No. VLC ships with every codec a camera uses. When VLC can't recognize a camera file, the file's map is missing.
- Can VLC repair the file? No. VLC has a repair option for AVI files only. For MP4 and MOV you need a program that rebuilds the map from a sample clip, such as untrunc.
- The file plays for a bit and then stops? Different problem: the file has a map but part of the footage is missing, usually from an interrupted transfer. Get the file again from the source.
If you're stuck
If the file is big, if the second run also came out jittery, or you just don't have the head for this right now, send me a link to the file and to a healthy clip from the same camera. I first check whether the footage is actually in the file and tell you where you stand. That check is free. If there's something to recover and you want to go ahead, you get a price for the file. You pay, and then the work starts. And if I couldn't recover it, you get your money back, all of it or part of it, depending on the result.
Prefer email? avihaiteram@gmail.com
Who I am
Avihai Teram, videographer and video editor. I shoot on a Sony FX3 and work with camera files like these every day, so I know how a camera writes them and what breaks when it shuts off mid-recording, and I have brought files like these back from Sony and DJI cameras. Send me a file that won't open: the first check is always free, and if I couldn't recover it, you get your money back. You can also find me on Instagram: @avihai.teram.