NVR and DVR Video Recorders

Which cameras can it read? DVR, NVR and hybrid inputs

A DVR takes analog or HD-over-coax cameras on BNC inputs and encodes the video itself. An NVR takes digital streams from IP cameras over the network and often supplies PoE. Some units are hybrid and take both. The channel count, such as 4, 8, 16 or 32, is the maximum number of cameras, and an NVR should list the protocols it supports, such as ONVIF, if you mix camera brands. Some features, such as smart detection, may work only with cameras of the same maker.

Compression, bandwidth, bays and outputs

H.265 and H.264 are the usual video compression formats, and H.265 needs less storage for the same quality. The recorder's total input bandwidth must exceed the combined bitrate of the cameras. Check the number of drive bays and the largest drive each accepts, and look for RAID bays or dual power supplies when you cannot risk losing recordings. For viewing, HDMI carries 4K to a monitor, while VGA is an older connection. Network ports run at 1 Gbps or, on large units, 10 Gbps SFP+.

Questions about NVR and DVR Video Recorders

How many channels do I need?

One for each camera now, plus spare ones for future cameras. Recorders come in 4, 8, 16 and 32 channels and above, and going up one size avoids replacing the recorder when you add cameras.

Can I mix camera brands on one NVR?

Often yes, if the cameras and recorder support ONVIF. Basic live view and recording usually work, but features such as smart detection, two-way audio or maker-specific settings may need cameras from the same brand.

Does an NVR include a hard drive?

Check the listing. Many recorders are sold without drives and expect you to fit surveillance-rated disks. Note the bay count, the maximum capacity per drive and whether the unit supports RAID for protection against drive failure.