This one comes with all the information about the device, instead of a story. The drive is from a Dahua 16-channel surveillance recorder, and it was sent in for recovery of its recorded video. CCTV recorders do not save video as normal files: they write a single, proprietary stream (continuously) that the drive was designed to store; therefore, recovering usable video will require an understanding of how that particular recorder records (its recording format), not just a file system read. The drive itself is a standard hard disk, but what is written on it follows the recorder's own scheme, and that is the whole of the work.
| Media | Hard drive from a Dahua 16-channel digital video recorder (XVR series) — surveillance footage the target, stored in the recorder's proprietary format. |
| Reported situation | Drive removed from a Dahua CCTV recorder · footage recovery required · full recorder model and firmware details supplied · the type and extent of recovery to be confirmed · standard hard drive, proprietary recording format. |
| Fault class | Recovery of proprietary surveillance video — either a drive hardware fault to address first, or footage to extract and reconstruct from the recorder's non-standard format, or both; the format the defining challenge. |
| Equipment used | Drive health first assessed on PC-3000 UDMA and imaged under a hardware write-blocker on DeepSpar Disk Imager if any hardware fault is present · the recorder's proprietary filesystem and video stream analysed on the image, the continuous recording parsed into per-channel, time-indexed footage · frames carved and reassembled where the recorder's structures are damaged · recovered footage validated by playback, exported to a standard viewable format. |
The key fact about surveillance recorders is that they are based on their own formats rather than a standard file system. A CCTV recorder does not save each individual segment (clip) as a file like you would find on your personal computer. The system writes a continuous video stream from all of its channels into a custom-designed format for continuous recording and overwrite purposes, in this case, Dahua's own format. Therefore, when you pull a hard drive out of such a recorder, there will not be browsable video files located on the disk. Instead, the format used by the recorder will have been recorded onto the disk, and that format must be understood and parsed to extract any footage. This is the main part of the job, and it is what makes surveillance recovery different from simply recovering files off a storage device.
Two questions are answered in order: is the drive healthy, and can the format be read. The initial step will be to check the hardware, as the drive is a standard hard disk which is capable of failure similar to all hard disks. If there is a fault, then it will need to be addressed and the drive imaged prior to anything else. The second step will be to reconstruct the footage by parsing the proprietary recording from that image. A drive can have both a hardware fault and a format to decode, and each one is handled in turn.
Rebuilding the footage allows for converting an unbroken stream of information to usable video with time indexes. The recorder stores video as an interleaved stream from all sixteen input channels. Recovery separates this back into the individual channel streams to create video indexed by time, so specific cameras or periods can then be easily located. If the recorder's internal structures are intact, this follows its format directly; if they have been damaged, the video frames have to be carved out and put back together again based on their patterns. Once rebuilt, the output is actual viewable video, not just a raw data stream.
Everything is done on an image, which protects a possibly-overwriting system. Surveillance recorders continuously overwrite the oldest footage, so the drive should not be left running in the recorder once the needed footage exists. It is imaged and all reconstruction happens on the copy, so no further recording can overwrite what is being recovered, and the format analysis can be exhaustive without risk.
There is an honest prognosis of recovery, based upon the health of the drive and how much footage remains. If the hard drive is in good condition or the fault is fixable, and the needed footage has not yet been over-written by the recorder's normal cycle, it will be very possible to successfully recover and export the video into a standard video format. The real limits would be a severe fault on the drive, or footage that had already been over-written before the drive was pulled out; this is established at the assessment, and what is recoverable and viewable is confirmed before there is any charge.
Drive health was first assessed on PC-3000 UDMA and the drive imaged under a hardware write-blocker on DeepSpar Disk Imager where a hardware fault was present. The recorder's proprietary filesystem and video stream were analysed on the image, the continuous recording parsed into per-channel, time-indexed footage, and frames carved and reassembled where the recorder's structures were damaged. The recovered footage was validated by playback and exported to a standard viewable format.
Once the drive's health had been addressed, the proprietary recording was parsed and reassembled into viewable per-channel footage, and the recovered video was then exported in a standard file format. There are no charges associated with the diagnostic, which is completed within two working days of the drive arriving. A single quote will be provided as one fixed, written figure, which already includes VAT. Opening a drive is an invasive procedure, therefore 50% of the total quote is payable upfront to cover the cost of donor parts and lab time, and the remaining balance is only due if the data comes back. The process to decode: CCTV recorders produce a continuous proprietary stream rather than creating individual files, therefore recovering the footage means decoding the recorder's format, not reading a filesystem, and once this is parsed correctly the sixteen channels will come back as viewable and time-indexed video.
Turn off the recorder once you know you need footage. Surveillance recorders are always recording over their oldest clips, so if you leave the recorder on while you're trying to recover an old clip, you'll likely lose what you're looking for. Don't expect to see your disk with videos listed that you can browse, as the recorder writes them as a proprietary stream that has to be decoded, so the average recovery software won't produce usable footage. Also note down exactly what model of recorder you have since each one has its own unique format. Get a quote, then have the recorder's hard drive imaged and the recorded footage reconstructed and exported into a standard format you can actually play.
Our case files are written up from genuine enquiries our lab has handled for customers across Swansea and South Wales, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery approach our engineers apply to that fault, using the equipment listed.
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