CCTV and camera technology definitions and glossary

There is so much jargon in CCTV technology that it can be overwhelming. This is the A–Z Handykam published to cut through it, covering the video, recording, connector and network side of the subject. Its companion, covering nest boxes, wildlife camera hardware and the terminology of watching birds, is the wildlife camera glossary.

A

Analogue

A camera producing a continuous video waveform carried on a cable to a screen or recorder, rather than digital data on a network. Simple, mature, and capped in resolution by the signal standard it uses.

Aperture

The area of the lens that gathers light, controlled by the iris. A wider aperture gathers more light and gives a shallower depth of field.

B

Bit rate

How much data per second a stream uses. It is the honest measure of video quality, and often more informative than resolution — a heavily compressed 4K stream can look worse than a generous 1080p one.

BNC

Bayonet Neill–Concelman connector: a twist-and-lock connector used widely in professional video. Many recorders use BNC inputs, and a small converter lets phono plugs connect to them.

C

CCD

Charge-Coupled Device — a type of image sensor that converts light into an electrical signal. The dedicated sensor technology behind most of the analogue cameras in this archive, and historically the better performer in low light.

CCTV

Closed Circuit Television: a camera system whose pictures go to a defined set of screens and recorders rather than being broadcast.

CMOS

Complementary Metal Oxide Semiconductor — the other main image sensor technology, sharing its manufacturing process with memory chips. Historically the cheaper option and now, having improved enormously, the dominant one.

Coaxial cable

Cable with a central conductor inside a screen, used for analogue video over longer distances than a simple AV lead will carry.

Compression

Reducing file size. How much you can compress, and how much quality it costs, depends on the codec — see H.264. A bitmap image of 240KB may be 24KB as a compressed video frame.

D

DHCP

The service, normally running on a home router, that hands out IP addresses automatically. A recorder or camera set to DHCP will simply appear on the network without being configured.

Dome camera

A camera in a low hemispherical housing. Discreet, hard to re-aim casually, and better suited to ceilings and soffits than to wildlife work.

DVR

Digital Video Recorder: records video as digital files on a hard drive, usually from analogue cameras, with several channels reviewable later. See the DVR and NVR FAQ.

E

Encryption

Scrambling a signal so it cannot be read in transit. Available on network cameras; not possible on an analogue video cable, which is one of the strongest arguments for IP in a security context.

F

Frame rate

Video is a sequence of stills; frame rate is how many per second. Higher rates look smoother and cost proportionally more storage and bandwidth.

H

H.264 and successors

The video compression standards that make multi-camera recording practical at all. The storage worked example in the recorder FAQ assumes H.264.

HDMI

The standard digital audio and video connector on modern displays. Recorders output to it; analogue cameras need a converter to reach it.

I

IP

Internet Protocol — see How do IP cameras work?.

IP address

The unique number identifying a device on a network, commonly of the form 192.168.1.64 on a home network. Knowing how to find a camera's address on the router is the single most useful piece of networking for a camera owner.

IR

Infra-red. Light beyond the visible red, used to illuminate a scene invisibly at night.

L

LAN

Local Area Network — the network inside one building. Cat5 and Cat6 are the usual cable categories.

Lens, board / M12

The small screw-in lenses used on board cameras, threaded M12. Focal length sets the angle of view: a short focal length such as 3.6mm is wide and suits a nest box interior; longer lenses narrow the view and reach further. See CCTV camera lenses and board lens tips.

Lux

A unit of illumination, used to state the lowest light level at which a camera can still produce a picture.

N

NVR

Network Video Recorder: records IP cameras over the network, often supplying power to them over the same cable.

O

ONVIF

An open interface standard for network video devices. An ONVIF-compliant camera can be used with third-party apps and recorders rather than being tied to one manufacturer — worth insisting on.

P

PAL

The analogue television standard used in the UK, at 625 lines and 25 frames per second. It sets the ceiling on what an analogue camera can deliver regardless of sensor quality.

Phono

See RCA.

PoE — Power over Ethernet

Carrying electrical power along the same network cable as the data, so one run does both jobs. The neatest way to install a network camera at a distance.

Port forwarding

Configuring a router so a device inside the network can be reached from the internet. Powerful, and the usual route by which cameras end up publicly accessible with default passwords. Prefer a manufacturer app or a VPN.

PTZ

Pan, tilt and zoom: a camera that can be aimed and zoomed remotely by motor.

R

RCA plug

Named after the Radio Corporation of America; also called a phono or CINCH connector. The familiar colour-coded audio and video connector: yellow for video, white for audio, and on camera cables of this type red for 12v power.

Resolution

The detail a camera can record, quoted in television lines for analogue cameras and megapixels for digital ones. The two are not directly comparable — see Camera resolution.

RTSP

Real Time Streaming Protocol, defined in RFC 2326: the standard way a network camera publishes a live stream for viewers to subscribe to, usually on port 554.

S

SCART

A 21-pin audio-visual connector of French origin, also called Euroconnector or Peritel, standard on European televisions for decades. Camera kits shipped with a phono-to-SCART converter for exactly this reason.

Signal-to-noise ratio

How much of what the sensor produces is picture rather than electrical noise, in decibels. Higher is cleaner; it matters most in low light, which is where nest box cameras live.

Splitter

A device that sends one AV signal to several destinations — televisions, computers — simultaneously.

Switcher

A device that lets you change between several cameras on one screen without unplugging anything.

T

TVL

Television Lines, or Lines of Horizontal Resolution: the standard measure of an analogue camera's resolving power, counted relative to the picture height. More lines means a sharper image.

U

USB capture device

A small device that digitises an analogue camera's AV signal into a computer over USB, supplied with software to capture, review and delete footage. The cheapest route from an old camera to a hard disk.

V

Varifocal

A lens whose focal length can be adjusted, so the angle of view can be set on site rather than fixed at purchase. Considerably more forgiving on an installation where you cannot easily move the camera.

W

White balance

The camera's correction for the colour of the ambient light, so that white looks white under daylight, cloud or artificial lighting. Almost always automatic.

Related pages: Wildlife camera glossary · Digital IP versus analogue · DVR and NVR FAQ