Surveillance DVR and NVR systems store footage on hard drives using proprietary file systems that no PC, Mac, or Linux machine can read. When the drive fails or the footage disappears, the video data is still on the platters, but accessing it requires both physical drive repair and proprietary file system parsing.
We recover footage from Hikvision, Dahua, Swann, Lorex, NightOwl, and other surveillance systems. Physical drive repair using PC-3000, followed by file system identification and video stream extraction. Footage is delivered in standard MP4 format playable on any device.
When you connect a DVR hard drive to a Windows PC, Disk Management will show it as "Not Initialized" or "Unallocated" and prompt you to initialize and format it. This is because Windows does not recognize the proprietary surveillance file system. Clicking "Initialize" or "Format" permanently destroys all surveillance footage. The drive is not empty or corrupted; Windows simply cannot read the file system. Disconnect the drive and contact a recovery lab instead.
DVR and NVR manufacturers use proprietary file systems designed for continuous sequential video writes, not random-access file storage. These file systems prioritize sustained write throughput and circular overwrite (oldest footage deleted first when the drive fills) over compatibility with standard operating systems.
The drive itself is a standard SATA HDD (WD Purple, Seagate SkyHawk, or Toshiba surveillance-series). The hardware is identical to any desktop or NAS drive. What makes it unreadable is the data layout on the platters; the DVR formatted the drive with its own file system that only the DVR firmware knows how to interpret.
Standard data recovery tools (R-Studio, Disk Drill, Recuva) scan for known file system signatures: NTFS, ext4, XFS, HFS+, FAT32, exFAT. Surveillance file systems use entirely different signatures and data layouts. These tools will report the drive as empty or unformatted even though gigabytes of video data exist on the platters.
Recovery requires specialized software that understands each manufacturer's proprietary format. The DVR brand determines the file system, not the drive brand. A WD Purple drive from a Hikvision NVR has a completely different data layout than the same WD Purple drive from a Dahua NVR.
Hikvision is the world's largest surveillance equipment manufacturer. Their DVRs and NVRs use a proprietary file system with no public specification. Forensic analysis (Han & Jeong, ICDF2C 2015) identified the following on-disk structure:
Located at disk offset 0x200. Contains the signature HIKVISION@HANGZHOU (18 bytes). Defines the disk layout: total capacity, system log offset, video data area offset, data block size, total data block count, HIKBTREE index offset, and the system initialization timestamp (UNIX epoch). A backup Master Sector follows the system logs area for redundancy.
Raw H.264 (or H.265 on newer units) video stored in data blocks, typically 1 GB each. Each data block contains sequential video frames from one channel and an IDR table at the end (signature: OFNI) that indexes keyframe positions within the block. Video frames are stored as raw NAL units; there is no MP4, AVI, or MKV container wrapping the video.
A B-tree structure (signature: HIKBTREE) that maps recording timestamps to data block locations. Each entry includes the channel identifier, start/end timestamps, and a data block offset pointer. When the DVR's circular recording overwrites old footage, the corresponding HIKBTREE entry's existence flag changes from 0x00 (full) to 0xFF (empty). Recovery of overwritten blocks is not possible once this flag is set and new data has been written.
Each log entry begins with the signature RATS. Stores UNIX timestamps of DVR events: power on/off, recording start/stop, alarm triggers, user logins, and configuration changes. These logs are useful in forensic investigations to establish a timeline of DVR activity independent of the video recordings.
Dahua, the second-largest surveillance manufacturer, uses a proprietary file system called DHFS (Dahua File System). Current devices run DHFS 4.1. Unlike Hikvision's format, Dahua wraps each video frame in a DHAV container with header and footer signatures that enable frame-level validation during recovery.
Each DHAV frame begins with the ASCII header DHAV (uppercase) and ends with the footer dhav (lowercase). The 24-byte header contains: frame type identifier (1 byte at offset 4; 0xFD = video, 0xF0 = audio), channel identifier (1 byte at offset 6), frame number (32-bit little-endian at offset 8), frame length (32-bit little-endian at offset 12), and timestamp (32-bit little-endian at offset 16). The video payload begins at offset 24.
This dual-signature design (uppercase header, lowercase footer) means recovery tools can validate individual frames even when the surrounding file system metadata is corrupted. FFmpeg includes a DHAV demuxer (libavformat/dhav.c) that can parse raw DHAV frame streams, which makes Dahua footage reconstruction possible even from heavily damaged disk images.
Surveillance drives run 24/7 for months or years. Head crashes, motor bearing failure, and firmware corruption are the most common physical failures. If the drive clicks, does not spin up, or is not detected in BIOS, we repair it using PC-3000 and create a sector-by-sector clone to a healthy drive before touching the data layer. This is identical to standard hard drive data recovery.
Scan the cloned image for manufacturer signatures.HIKVISION@HANGZHOUidentifies a Hikvision file system.DHAVframe headers identify Dahua DHFS. Other brands (Swann, Lorex, NightOwl) often use shared proprietary formats from their OEM chipset supplier (commonly HiSilicon). Each requires a different parsing approach.
Parse the proprietary index structures to map recording timestamps to physical data block locations. In Hikvision systems, the HIKBTREE index enables date/time range extraction. In Dahua systems, DHFS metadata serves the same function. If the index is corrupt (common after power loss), we fall back to raw video carving in the next step.
Extract raw H.264 or H.265 video from the proprietary data blocks. For unfinalized recordings (footage that was being written when power was lost), we scan the raw data area for NAL start codes (0x00 0x00 0x00 0x01) and identify frame types: IDR keyframes (NAL type 5), SPS/PPS decoder configuration (NAL types 7 and 8), and inter-coded frames (NAL type 1). These are reassembled into playable video sequences and wrapped in standard MP4 containers.
DVR systems write video frames to disk in real time but update their file system index on a separate schedule. When power is cut during active recording, the video data from the most recent segment exists on the platters but the index does not reference it. The DVR treats this segment as if it never existed.
This is the single most common reason for "missing footage" on DVR systems. The recording was not lost; the index was not updated before power was cut. Recovery involves bypassing the index entirely and scanning the raw video data area for frame signatures. In Hikvision systems, we look for H.264 NAL units within data blocks that have no corresponding HIKBTREE entry. In Dahua systems, we scan for orphaned DHAV frame pairs (uppercase header, lowercase footer) outside the DHFS metadata scope.
The critical risk factor is circular overwrite. If the DVR continued recording after power was restored and the drive was full, the system will overwrite the oldest data blocks first. If the unfinalized segment occupied those oldest blocks, the video frames may already be partially or fully overwritten. The sooner the drive is pulled from the DVR after a power loss event, the higher the likelihood of recovering the unindexed footage.
When both the proprietary file system and its metadata index are too damaged to parse, we fall back to raw H.264 frame carving directly from the disk image. This is the last-resort recovery method and produces results even when no file system information survives.
H.264 video is composed of NAL (Network Abstraction Layer) units, each preceded by a 3-byte (0x00 0x00 0x01) or 4-byte (0x00 0x00 0x00 0x01) start code. The byte following the start code identifies the NAL unit type: type 5 is an IDR keyframe (the starting point of a decodable sequence), types 7 and 8 are SPS (Sequence Parameter Set) and PPS (Picture Parameter Set) containing decoder configuration (resolution, frame rate, encoding profile), and type 1 is a non-IDR inter-coded frame.
The carving process scans the raw disk image for these start codes, classifies each NAL unit by type, and reassembles them into playable sequences. SPS and PPS parameters are essential for playback; if they are lost from the damaged sectors, compatible parameters must be reconstructed based on the DVR model's known encoding settings. The reassembled H.264 stream is then wrapped in an MP4 container with synthesized timing metadata.
Frame carving recovers video content but loses the original timestamp associations. The footage can be placed in approximate chronological order based on frame sequence numbers and any surviving metadata fragments, but exact date/time accuracy depends on how much of the file system index survived.
| Brand | File System | Video Format | Notes |
|---|---|---|---|
| Hikvision | Proprietary (HIK) | .dav / raw H.264 | HIKBTREE index, OFNI IDR tables, RATS system logs |
| Dahua | DHFS 4.1 | DHAV / raw H.264 | Dual-signature frames (DHAV/dhav), FFmpeg demuxer available |
| Swann | Varies by model | H.264 / H.265 | Many models use HiSilicon chipsets with shared OEM firmware |
| Lorex | Varies by model | H.264 / H.265 | Some models rebadged from Dahua; may use DHFS |
| NightOwl | Varies by model | H.264 | Consumer-grade; often uses generic HiSilicon-based firmware |
| Samsung / Hanwha | Proprietary | H.264 / H.265 | Wisenet series; enterprise-grade, different from consumer Samsung |
Many lower-cost DVR brands are white-label products built on shared HiSilicon chipsets. These may use the same proprietary file system as their OEM source. If your DVR brand is not listed, contact us with the brand and model number; the file system is determined by the internal chipset, not the label on the box.
DVR and NVR systems use surveillance-rated drives designed for 24/7 continuous sequential writes. These drives have firmware optimizations for sustained throughput and vibration tolerance in multi-drive enclosures. When they fail, the physical recovery is identical to any HDD; the difference is in the file system layer above.
Desktop drives in DVRs: Using a non-surveillance drive (WD Blue, Seagate Barracuda) in a DVR shortens the drive's life. Desktop drives are rated for 8-12 hours of operation per day and lower annual write workloads. Running them 24/7 in a continuous write environment accelerates bearing wear, increases reallocated sector counts, and leads to premature head crashes.
Break-ins, robberies, assaults, and property crimes captured on surveillance cameras. Law enforcement may need footage from a specific date/time range. We can extract targeted segments when the HIKBTREE or DHFS metadata is intact, preserving chain of custody documentation.
Fire damage, flooding, vehicle accidents, and liability incidents. Insurance adjusters and attorneys request surveillance footage as evidence for claims processing. Footage is delivered in standard MP4 format with timestamp metadata when available.
Warehouses, retail stores, restaurants, and facilities with regulatory recording requirements. A failed DVR drive does not eliminate the compliance obligation. Recovery of the footage restores the documentation trail.
DVR recovery pricing depends on two factors: the physical condition of the drive and the complexity of the file system parsing. If the drive is mechanically healthy (no clicking, spins up, detected in BIOS), the cost covers proprietary file system parsing and video extraction only. If the drive has a physical failure, standard HDD repair pricing applies for the drive repair, with file system parsing included.
| Service Tier | Price | Description |
|---|---|---|
| Simple CopyLow complexity | $100 | Your drive works, you just need the data moved off it Functional drive; data transfer to new media Rush available: +$100 |
| File System RecoveryLow complexity | From $250 | Your drive isn't recognized by your computer, but it's not making unusual sounds File system corruption. Accessible with professional recovery software but not by the OS Starting price; final depends on complexity |
| Firmware RepairMedium complexity – PC-3000 required | $600–$900 | Your drive is completely inaccessible. It may be detected but shows the wrong size or won't respond Firmware corruption: ROM, modules, or translator tables corrupted; requires PC-3000 terminal access Standard drives at lower end; high-density drives at higher end |
| Head SwapHigh complexity – clean bench surgery50% deposit | $1,200–$1,500 | Your drive is clicking, beeping, or won't spin. The internal read/write heads have failed Head stack assembly failure. Transplanting heads from a matching donor drive on a clean bench 50% deposit required. Donor parts are consumed in the repair |
| Surface / Platter DamageHigh complexity – clean bench surgery50% deposit | $2,000 | Your drive was dropped, has visible damage, or a head crash scraped the platters Platter scoring or contamination. Requires platter cleaning and head swap 50% deposit required. Donor parts are consumed in the repair. Most difficult recovery type. |
Our "no data, no fee" policy applies to hardware recovery. We do not bill for unsuccessful physical repairs. If we replace a hard drive read/write head assembly or repair a liquid-damaged logic board to a bootable state, the hardware repair is complete and standard rates apply. If data remains inaccessible due to user-configured software locks, a forgotten passcode, or a remote wipe command, the physical repair is still billable. We cannot bypass user encryption or activation locks.
All tiers: Free evaluation and firm quote before any paid work. No data, no fee on simple copy, file system, and firmware tiers. Head swap and surface damage require a 50% deposit because donor parts are consumed in the attempt.
Target drive: The destination drive we copy recovered data onto. You can supply your own or we provide one at cost. For ultra-high-capacity drives (20TB and above), the target drive costs approximately $400+ due to the large media required. All prices are plus applicable tax.
Free evaluation. Firm quote before any paid work begins. No data recovered means no charge. Call (512) 212-9111 or request an evaluation online.
No. Hikvision uses a proprietary file system that is not ext, NTFS, FAT, or any format Windows or Linux recognizes. Connecting the drive to a PC shows it as 'Unallocated' in Disk Management. Windows will prompt you to initialize and format the drive. Accepting that prompt permanently destroys all surveillance footage. Hikvision provides a 'Local Playback' utility that can read intact drives over a USB adapter, but it cannot recover footage from a drive with physical damage or file system corruption.
DAV is Hikvision's proprietary video container format. It wraps H.264 or H.265 video streams in a non-standard container that most media players cannot open. VLC, Windows Media Player, and QuickTime will not play .dav files natively. Hikvision's own player software can play them. For recovery purposes, we extract the raw H.264 stream from inside the .dav container and re-wrap it in a standard MP4 container for universal playback.
Usually yes, for footage recorded before the power loss. DVR systems write H.264 video frames to disk in real time, but update the file system index (the part that makes footage searchable by date/time) on a separate schedule. Power loss interrupts the index update, so the most recent recording segment becomes 'invisible' to the DVR even though the raw video data is on the platters. We recover unfinalized footage by scanning the raw data area for H.264 NAL start codes and reassembling the video frames. The risk: if the DVR continued recording after power was restored, it may have begun overwriting that unindexed footage with new recordings.
DVR recovery starts at $300 for drives with no physical damage that need proprietary file system parsing. Drives with head failures, motor seizure, or platter damage follow our standard HDD pricing tiers. The forensic video reconstruction step (parsing the proprietary file system, reassembling unfinalized streams, carving H.264 frames) is included in the quoted price. Free evaluation. No data recovered means no charge.
Both are surveillance-rated drives designed for 24/7 continuous write workloads. WD Purple is rated for 180 TB/year write workload (Pro variant: 550 TB/year). Seagate SkyHawk is rated for 180 TB/year with rotational vibration sensors for multi-drive NVR enclosures (AI variant: 550 TB/year). Both use standard CMR platters and have failure modes identical to other enterprise HDDs: head crashes, motor seizures, firmware corruption, and reallocated sector accumulation. The recovery procedure for the physical drive is the same as any HDD. The difference is in the file system layer, which is determined by the DVR brand, not the drive brand.
Yes, if the metadata index is intact. Hikvision stores a HIKBTREE index that maps timestamps to data block locations on disk. Dahua stores equivalent metadata in DHFS. If these indexes survive, we can extract footage from specific date and time ranges. If the index is corrupted or the blocks have been overwritten by circular recording, we fall back to sequential H.264 frame carving, which recovers all surviving video but loses the timestamp associations.
Our Austin lab operates on a transparency-first model. We use industry-standard recovery tools, including PC-3000 and DeepSpar, combined with strict environmental controls to make sure your hard drive is handled safely and properly. This approach allows us to serve clients nationwide with consistent technical standards.
Open-drive work is performed in a ULPA-filtered laminar-flow bench, validated to 0.02 µm particle count, verified using TSI P-Trak instrumentation.
Serving clients nationwide via mail-in service since 2008.
Our repair work has been covered by The Wall Street Journal and Business Insider, with CBC News reporting on our pricing transparency. Louis Rossmann has testified in Right to Repair hearings in multiple states and founded the Repair Preservation Group.
Our "No Data, No Charge" policy means we assume the risk of the recovery attempt, not the client.
Louis Rossmann
Louis Rossmann's well trained staff review our lab protocols to ensure technical accuracy and honest service. Since 2008, his focus has been on clear technical communication and accurate diagnostics rather than sales-driven explanations.
We believe in proving standards rather than just stating them. We use TSI P-Trak instrumentation to verify that clean-air benchmarks are met before any drive is opened.
See our clean bench validation data and particle test videoFree evaluation. Proprietary file system parsing for Hikvision, Dahua, and other DVR systems. Footage delivered in standard MP4 format. No data recovered, no charge.
