DVR vs NVR: which one do you have, and what does it mean for your cameras?

A DVR (digital video recorder) works with analog cameras. Each camera sends its picture down a coax cable to the recorder, which turns it into digital video and stores it on the hard disk.

An NVR (network video recorder) works with IP cameras. The camera turns its own picture into digital video and sends it over a network cable, and the NVR stores it. Many NVRs have their own PoE sockets, so one cable carries both power and video to each camera.

An XVR, or hybrid recorder, takes analog cameras and can also take some IP cameras. Dahua calls its XVRs "Penta-brid" because one unit takes four kinds of analog camera (HDCVI, AHD, TVI and CVBS) and IP cameras. CP Plus's all-in-one recorders, which it says use UNI+ technology, list the same five kinds of input.

People often say "DVR" for any recorder box, even when it is an NVR, so go by the box itself and not the word your installer used. In India the box is usually just called the DVR. In the US and UK, sellers tend to call a kit with PoE cameras an NVR system and a kit with coax cameras a DVR system.

You need two minutes and no tools.

• Look at the back of the recorder. A row of round twist-lock sockets (BNC) means analog inputs, so it is a DVR or an XVR. Dahua's pages list an XVR's analog sockets as BNC ports. A row of network sockets (RJ45), often marked PoE, means an NVR. Dahua's 8-channel PoE NVR, for example, lists eight PoE ports plus one separate network port. Every recorder has one network socket for your router, so a single network socket tells you nothing. Look for a row of camera sockets.
• Follow one camera cable back to the recorder. A thin cable with a round connector, usually with a separate power lead near the camera, is an analog camera. A network cable with a clip-in plug like the one on your router is an IP camera.
• Read the model name on the sticker under the box, or on the box it came in. Dahua puts the type in the name: DH-XVR4B08H-I is an XVR and NVR4108-8P-4KS3 is an NVR. CP Plus's analog and hybrid recorders have UVR in the name, as in CP-UVR-0401E1-CV2.
• Check the menu. Open the recorder's menu on its screen and look for System Info, Device Info or Version. The name differs by brand. It shows the model name and the serial number.
• If you still cannot tell, photograph the back of the box and its sticker. Your installer or the brand's support can tell from the model name.

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A DVR has a fixed number of camera inputs, such as 4, 8, 16 or 32, and each camera uses one coax cable and one input. The picture quality is capped by what the recorder supports. CP Plus's CP-UVR-0401E1-CV2, for example, is listed as a 4-channel 1080N recorder.

To add a camera you need a free input of the right type. HDCVI, AHD, TVI and CVBS are different analog signal types. Recorders such as Dahua's XVRs and CP Plus's UVR range detect the type on each input by themselves. An older recorder may take only one type, so check its manual before you buy a camera.

An IP camera will not plug into a DVR's coax socket. Only a hybrid recorder with IP inputs takes IP cameras, and only up to its limit. Dahua says its HDCVI systems can reuse existing cables, because HDCVI is compatible with both coaxial cable and UTP network cable.

A hybrid lets you upgrade in steps. You keep the analog cameras and cables that work, and add IP cameras where you need a sharper picture, up to the recorder's limit. CP Plus gives the reason on its datasheet: some features exist only on IP cameras, such as two-way talk, edge storage and alarm inputs and outputs.

• The limits depend on the model. CP Plus's 4-channel CP-UVR-0401E1-CV2 takes up to 5 IP cameras of up to 2MP each. Dahua's DH-XVR4B08H-I lists 8 plus 4 channels, each up to 6MP.
• Adding IP cameras can use up analog inputs. One Dahua XVR's product page lists 2 IP channels by default and 8 more where analog channels are converted to IP channels.
• Extra IP channels can switch off the recorder's own smart features. The same Dahua page says that after IP extension is enabled, the recorder's smart motion detection is disabled. Check this for your model before you count on both.

An NVR records IP cameras. Each camera needs a network cable, and power either from a PoE socket on the NVR, from a PoE switch, or from its own power adapter. A standard network cable run is limited to about 100 metres, so long runs need a switch partway.

• Any brand can work if the camera and recorder both support the ONVIF standard. Dahua's 8-channel PoE NVR lists ONVIF Profile S, T and G. Check your recorder's datasheet.
• Cameras plugged into an NVR's own PoE sockets sit behind the recorder. Dahua's NVR manuals say they are isolated from the outside world and cannot be accessed directly. You see them through the recorder, not by typing the camera's own address.
• Analog cameras do not plug into an NVR. Hikvision's support says you need an encoder that turns analog inputs into IP channels the NVR can add.
• Count the channels. An 8-channel NVR takes 8 cameras, and a 16-channel one takes 16.

Phone apps talk to the recorder, not to each camera, so a DVR, an XVR and an NVR work the same way. You add the recorder, then you see its cameras. The app depends on the recorder's brand: Hik-Connect for Hikvision, DMSS for Dahua, gCMOB on Android or iCMOB on iPhone for CP Plus, and XMEye for many unbranded recorders. Our CCTV on mobile guide shows how to find your brand and add the recorder by QR code or serial number.

Brand guides: Hik-Connect login, DMSS, gCMOB login and XMEye.

On a PC, each brand has its own free software: iVMS-4200 for Hikvision, SmartPSS Lite for Dahua and KVMS Pro for CP Plus. See our guides to iVMS-4200 Lite, SmartPSS Lite and KVMS Pro. If you cannot find your recorder on the network, the brand tools help: Hikvision SADP, Dahua ConfigTool and CP Plus IP Finder.

Software that watches your cameras needs their video. With IP cameras it can read the video from the recorder or from the cameras. With analog cameras behind a DVR it reads the video from the recorder, because an analog camera has no network address of its own.

Foreman is software that runs on a Windows PC at your site and watches the cameras and recorders you already have: Hikvision and Prama, Dahua, CP Plus, TVT, Uniview, Axis, Hanwha, and any RTSP or ONVIF camera, DVR or NVR. An XVR is a DVR that also takes IP cameras, so it counts as a DVR. It installs in 60 seconds and nothing on the wall changes.

In practice you need three things: the PC on the same network as the recorder, the recorder's address, and its username and password, the same ones the phone app asks for. Remember that the picture is whatever the recorder gives. An old analog camera gives a lower quality picture than a modern IP camera, and that limits what any software can see. Our AI camera guide explains what AI can and cannot do with a given picture.

• Keep what you have if the pictures are clear and the recorder records reliably. You can add software to a DVR or NVR you already own. Smoke and fire checks, people after hours and a warning when a camera goes offline do not need a new recorder or new cameras.
• DVR to XVR: worth it when the recorder is failing but the cameras and cables are fine, or when you want to upgrade cameras one at a time. You keep the coax.
• DVR to NVR with IP cameras: worth it when you need a sharper picture, more cameras than the DVR has inputs, or features only IP cameras have. It means new cameras and new cabling, so it is a bigger job.
• New recorder, same cameras: worth it when you cannot add channels, remote viewing never works, or the hard disk keeps failing. Our CCTV hard disk guide covers how much storage you need.
• Before you buy, count the cameras you need now and in two years, check the resolution the recorder supports, and check how many hard disks it holds. CP Plus's CP-UVR-0401E1-CV2, for example, takes one SATA disk of up to 6TB.