A network video recorder records IP camera streams and serves them back for live viewing and review. It is the central storage and management device in most modern camera systems. The specification that matters is throughput and retention, not just how many cameras it can list.
An NVR connects to cameras over the network, records their streams and provides the interface for viewing and exporting footage. The camera count on the box is a maximum, not a promise that every camera will record well.
NVR and DVR are different
A DVR takes analogue camera signals, usually over coax. An NVR takes IP streams over a network. Many sites run a hybrid arrangement while older analogue cameras are replaced, and some recorders support both.
What to size it for
The recorder has to handle the total bitrate of every camera at the resolution and frame rate you choose, not just the number of channels. Storage is then sized from that bitrate and the retention period.
- Camera count and the total incoming bitrate.
- Resolution and frame rate per camera.
- Retention period and the resulting disk capacity.
- RAID or a second recorder where a single failure is unacceptable.
- The number of simultaneous remote viewers.
Where the recorder lives
The recorder needs ventilation and a physically secure location. A network closet that floods or a shelf in an office is not a suitable home for the device that holds the evidence.
Related:Commercial security camera systemsGlossary: VMSGlossary: PoE