A recorder writes in a loop, so the first question is how long you have before the footage you need is written over. The arithmetic is simple and worth doing now — then take the disk out of service, because every hour it keeps recording is an hour of older material gone.
$ cdr triage /dev/sdb → Device: Hikvision NVR HDD · 6 TB → Status: FOOTAGE LOOPED OVER — oldest blocks → Target: 09 Feb, 22:15–00:45 · cam 5 $ cdr engineer-working → Read-only image: taken · recorder halted in time → File system: Hikvision layout · parsed → Streams: H.265 rebuilt by timestamp $ cdr verify → ✓ channel 5 — 2h 30m recovered → ✓ exported — MP4 + timestamps → ✓ footage recovered — incident captured
The most time-critical category we handle, and the urgency is structural rather than incidental.
A surveillance recorder is designed to run continuously and overwrite its oldest footage when the disk fills. That cycle is the whole point of the device, and it means the footage you need has a deletion date already set by the retention period and the number of cameras.
A four-camera system on a 1 TB disk might hold three weeks. A sixteen-camera system on the same disk might hold four days. If an incident happened last Tuesday and the system is still recording, the window is closing while the decision is being made.
So the first action is not to ring anybody. It is to stop the recorder overwriting — either by pulling the disk out or by powering the unit down entirely. Everything else can wait; that cannot.
Power it down now, then decide. If footage matters and it has not been exported, take the recorder out of service before anything else. A system left running while somebody arranges a quote is a system deleting the thing they wanted.
Connect a DVR disk to a computer and it usually shows as unformatted, which alarms people into thinking it has failed. It has not. Most manufacturers write their own file system rather than using NTFS or ext4, partly for performance under continuous write load and partly to keep footage inside their own software.
There are dozens of these formats across Hikvision, Dahua, Swann, Samsung, Bosch and the many rebadged units sold under other names, and they share no standard. Reading one means identifying the manufacturer's structure, locating the frame index, and reassembling video from fragments that were written continuously rather than as discrete files.
Which is why a normal recovery tool returns nothing from a CCTV disk even when the footage is entirely intact. It is looking for files, and there are no files — there is a circular buffer with an index.
The disk is what holds the footage. Send the recorder too if you are not confident removing it, or if the unit itself has failed rather than the disk.
Date and approximate time. Narrowing the window from a fortnight to two hours changes reconstruction from days of work to hours, and improves what is retrievable.
Identifies the format and the frame structure. Rebadged units are common, so the label matters more than what the box said when it was bought.
A sixteen-channel system interleaves all channels on one disk. Knowing which cameras matter lets us prioritise those channels rather than reconstructing everything.
CCTV and DVR recovery is £800 +VAT flat, agreed in writing after the free diagnostic. It is a single figure rather than a range because the work is the same on any recorder: identify the manufacturer's file system, locate the frame index, and reassemble video from a circular buffer that was never written as files.
Where footage is needed for a police matter or an insurance claim, a written account of what was recovered and how comes as standard rather than as an extra.
Power it down now. Every hour of continued recording overwrites older footage, and last week may be inside the overwrite window depending on camera count and disk size.
Expected, and not a fault. DVRs write proprietary file systems that Windows cannot read. Do not accept the offer to format — the footage is intact and unreadable only to your computer.
Partially, sometimes. Overwriting is not always complete or sequential, and fragments of older footage frequently survive between newer recordings. It is worth attempting rather than assuming.
Then we can almost certainly read it. The footage lives on the disk, not in the recorder, and the format is identifiable from the disk itself.
Helpful but not essential. The make and model off the label tells us the format. Send the unit if the disk will not come out easily or if the recorder itself has failed.
We supply it in a standard video format with a written account of what was recovered and from where. Whether it is admissible is a matter for whoever is handling the case.
A free diagnostic, footage recovered by camera and time from a DVR, NVR or SD card — even a failed recorder — and exported as standard files for your insurer or the police. Get in touch.