UK What an NVR does
An NVR, or network video recorder, is the recording and viewing hub of an IP camera system. Each camera compresses its own video, usually to H.264 or H.265, and sends it across the network. The NVR receives those streams, writes them to hard drives, and lets people watch live and recorded video on a local monitor, in a browser or in a phone app. It also keeps the evidence: footage can be searched by time or event and exported for investigations.
Because the cameras connect over Ethernet, they can be anywhere the network reaches, across a building, a campus or a fleet of vehicles. That is the main difference from the older DVR, which records analogue cameras wired directly to it with coax.
A complete NVR security system is the cameras, the network switches, the NVR with its storage, and the software people use to view and search the footage.
How an NVR records IP cameras
When a camera is added, the NVR discovers it on the network, usually through ONVIF or the maker’s own protocol, sets the stream format and requests the video over RTSP. It then records continuously, on a schedule or only when motion or an event is detected. Most cameras send two streams: a high-resolution main stream for recording and a lighter sub-stream for multi-camera live views and remote viewing.
Many NVRs include a built-in PoE switch, so each camera needs just one cable for data and power. Larger systems use separate PoE switches and a server-class NVR, often with RAID storage so footage survives a failed drive.
Types of NVR
NVRs range from small appliances to servers running video management software.
| Type | What it is | Typical scale | Best for |
|---|---|---|---|
| Embedded PoE NVR | Appliance with built-in PoE ports and fixed software | 4 to 32 cameras | Shops, offices, small sites |
| PC or server VMS | Computer or server running video management software | Tens to thousands of cameras | Campuses, multi-site estates |
| AI NVR | NVR with a GPU or AI accelerator running analytics | 4 to 64 cameras per recorder | Detection, counting, alerts on site |
| Industrial or mobile NVR | Fanless, rugged recorder for harsh or moving installations | 4 to 16 cameras | Trains, buses, roadside cabinets, plants |
| Cloud or hybrid | Recording in the cloud, or local NVR with cloud backup | Varies | Remote access across many small sites |
What an AI NVR adds
An AI NVR runs analytics on the recorder, so it does more than store video. Running analytics on the NVR means alerts happen on site, even if the connection to the cloud drops, and only flagged events need to be reviewed or sent on. Typical video analytics functions include:
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Detect and classify. People, vehicles and objects in every stream, instead of simple pixel-change motion detection.
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Watch zones. Virtual fences and restricted areas that raise an alert when crossed.
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Count. People or vehicles entering and leaving an area or a car park.
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Find footage fast. Search by event, object or colour instead of scrubbing hours of video.
How much storage an NVR needs
Storage depends on the number of cameras, their bitrate and how long footage must be kept. A camera streaming at 4 Mb/s around the clock writes about 43 GB a day, so 16 such cameras kept for 30 days need roughly 21 TB before allowing for RAID. Switching to H.265, recording only on events or lowering the frame rate can cut that substantially. Our guide to PoE in surveillance and NVR systems covers sizing the whole system.
Industrial NVRs add fanless, rugged designs for stations, vehicles and roadside cabinets, with wide DC input, wide temperature ranges and removable drive bays. The station AI NVR case study shows one in use, and our industrial NVRs cover PoE, AI and rail-certified recorders.
Choosing an NVR
Most NVR decisions come down to a handful of checks, made before the cameras are bought rather than after.
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Channels and throughput. Count the cameras now and later, and check the NVR’s total incoming bandwidth, not just its channel count, especially with 4K cameras.
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PoE budget. A PoE NVR has a total power budget as well as a port count. PTZ and heated outdoor cameras can draw far more than fixed cameras.
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Codec and decode capacity. Check that the NVR records H.265 and can decode enough streams at once for the live views operators need.
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Storage and redundancy. Size drive capacity for the retention period and choose RAID or hot-swap bays where footage matters.
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Environment. Office NVRs expect a clean, cool room. Vehicles, plant rooms and roadside cabinets need a fanless, wide-temperature recorder with wide DC input.
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Remote access and security. Use the maker’s secure remote access or a VPN rather than opening ports, change default passwords and keep the firmware up to date.
Quick answers on NVRs
NVRs: common questions
What does NVR stand for?
Network video recorder. It records video from IP cameras over a network, as opposed to a DVR, a digital video recorder, which records analogue cameras.
Does an NVR need the internet?
No. It needs a local network to reach the cameras, but it records without internet access. Internet is only needed for remote viewing and cloud features.
Can I use any IP camera with an NVR?
Usually, if both support ONVIF. Check that the camera and NVR share the same ONVIF profile, or that the NVR supports the camera maker’s protocol.
Does an NVR need PoE?
No, but it helps. A PoE NVR powers cameras directly. Without it, cameras need a PoE switch, injectors or local power supplies.
What is an NVR in CCTV?
The recorder of an IP CCTV system. It replaces the DVR of analogue CCTV and adds remote access, higher resolutions and analytics.
We supply industrial and AI NVRs with drives, operating system and camera configuration set up as standard, and validate recording and analytics before the system ships.