The loop explained
Loop recording explained: what it actually means
Loop recording means the camera writes footage in fixed length segments, then deletes the oldest segment once the memory card fills up, freeing space for the next one. That is how a dash cam keeps recording indefinitely on a card of finite size, without you ever having to delete files by hand. It only breaks down when something stops the deleting part from working, not the recording part.
How a fixed length segment works
The camera writes continuously into one segment file for a set duration, closes it, and starts the next. Once total recorded footage reaches the card's capacity, the next new segment overwrites the oldest segment that isn't locked. Nothing is deleted on a timer or a schedule: a segment is only ever removed to make room for the one being written now.
Why segment length matters
Most dash cams offer a choice of segment length, typically somewhere between one and five minutes depending on the model. A shorter segment makes it more likely an event sits inside a single file rather than split across two, and it means locking a clip ties up a smaller chunk of the card each time. A longer segment means fewer files to scroll through, but a single lock costs you more storage.
What a locked or protected file actually is
A locked file is a segment the camera has decided must not be touched by the loop. Most cameras trigger a lock automatically when the impact sensor registers a knock, and most also give you a manual lock button so you can protect a clip on demand, even without an impact. Locked segments are generally moved into, or flagged within, a separate protected area of the card, one that ordinary loop recording is not allowed to overwrite.
The failure mode people actually hit
This is the real reason a dash cam appears to "stop recording", far more often than any fault with the camera itself.
Every knock the impact sensor registers, a pothole, a speed bump, a car park bump, locks another segment. Locked segments do not get recycled, so they build up. Once the space the card sets aside for locked files runs out, the camera has to do one of two things depending on the model: refuse to lock anything else, or let the unlocked loop area shrink so far that recording itself starts to fail.
The full diagnostic sequence for this, cheapest check first, is on why your dash cam isn't recording everything.
Questions
What does loop recording mean on a dash cam?
It means the camera writes footage into fixed length segments and deletes the oldest segment once the card is full, so it can keep recording indefinitely without you managing storage by hand.
How long is each loop recording segment?
It depends on the camera and how you've set it, but most models offer segments somewhere between one and five minutes. Shorter segments keep an event inside a single file more often and let you lock a smaller chunk of card at a time.
What is a locked or protected video file?
A file the camera has flagged, either automatically because its impact sensor triggered or because you pressed a lock button, so ordinary loop recording is not allowed to delete it during the normal overwrite cycle.
Can loop recording actually stop working?
Yes. If locked files fill the space the card sets aside for them, the camera can run out of room to lock anything new, or the unlocked loop area can shrink so far that recording itself starts to struggle. That is the most common real cause of a dash cam that appears to have stopped recording.
Does a full card mean my dash cam has stopped recording?
Not on its own. A card that is merely full of unlocked loop footage is working exactly as designed. It's a card full of locked files specifically that causes problems, because that space isn't recycled the same way.
Last reviewed 10 July 2026