Fundamentals
Video recovery: containers, codecs and fragments
A video that plays its first seconds can break off in the middle. That is exactly what most checks miss.
The short answer
Videos are large, fragmented and therefore the hardest case.
A twenty-minute 4K clip takes many gigabytes and often sits spread across several non-contiguous areas. On deletion, the chain linking those areas is released in the FAT. A tool has to reconstruct it — and then demonstrate that the result is readable across the whole duration.
01 / Structure
Container and codec are two different things
MP4, MOV and MXF are containers: they bundle the picture track, audio tracks and management data. The actual picture content inside is encoded with a codec such as H.264, HEVC or ProRes. An intact container does not guarantee that the codec data inside is complete.
One point is especially awkward: in MP4 and MOV the management data can sit at the end of the file. If that end is missing, the player does not know the clip's structure and refuses to play — even though most of the picture data is still there. Conversely a clip can start normally and hit foreign data in the middle.
| Container | Typically from | Recovery specifics |
|---|---|---|
| MP4 | Drones, action cams, many cameras | Management data often at the file end |
| MOV | Apple ecosystem, Canon, Atomos | Built like MP4, different identifier |
| MXF | Broadcast, Sony XAVC, Canon XF | Complex structure, often several tracks |
| Matroska / WebM | Less common on cameras | More robust against interruptions |
02 / Procedure
The route to a verified clip
- 1
Take the card out of the camera at once and use a different one for the rest of the shoot.
- 2
Create an uncompressed image and work only with that — especially important for video, because scans take a long time.
- 3
Before scanning, note the camera, codec, resolution and approximate clip duration.
- 4
Scan deliberately for the container actually used, not for every video format at once.
- 5
Export to a different drive and plan for enough free space.
- 6
Check every clip across its whole duration, not just by starting it.
03 / Verify
How to recognise a complete clip
- The file plays from beginning to end without freezing or breaking off.
- The displayed duration matches the expected recording length.
- The file size fits the duration, resolution and the camera's data rate.
- All expected audio tracks are present and in sync with the picture.
- Jumping to the end shows a picture, not just a black frame.
- The file does not carry the .UNVERIFIED marking.
Many systems generate the thumbnail from the first frame. The rest of the clip is not read for it. A visible thumbnail therefore only tells you the start of the file is intact.
04 / Repair
Recovery and repair are two steps
First comes the attempt to retrieve the data from the source. If the result is structurally incomplete — because the management data is missing, for instance — a repair can complete the container so the clip becomes playable again.
What matters is the order and the traceability: the unmodified reconstruction is preserved and the repair result is added alongside it. It therefore stays visible which part came from the source and which from a reconstruction.
Common questions
My clip will not open but it is large. Is it lost?
Not necessarily. In MP4 and MOV the management data often sits at the end of the file. If that part is missing, the player refuses to play although the picture data is present. That is exactly where container repair applies.
Why are videos harder to recover than photos?
Because of their size and fragmentation. A photo usually sits contiguously, a long clip across many separate areas. The chain linking those areas is released on deletion and has to be reconstructed.
The clip starts and then freezes. What does that mean?
The start is intact; further in, data is missing or foreign data sits in its place. Often that area was already overwritten. The freezing part is then not recoverable.
How much storage do I need for the export?
Plan for at least the expected total size of the clips, preferably double. The export has to go to a physically different drive, never to the source.
Should I repair a damaged video before recovering it?
No. First secure the data unchanged from the source. Container repair is only a subsequent, additional step and never replaces the original reconstruction.
How long does video recovery take?
It depends on card size, read speed and the formats selected. Creating an image already takes time for large, fragmented clips; allow additional time afterwards to play each result through completely.