Camera’s basic function is to transmit what it 'sees' to a recording device, as well as to a user. Camera is the eye of the video surveillance system.

Digital cameras record images through a CMOS or CCD sensor, whose quality also affects the quality of the recorded footage. When the sensor has transmitted the image, the signal is modified inside the camera, depending on its type. With IP cameras, the image is encoded in various formats, depending on the codec (SMAC-M, H.264, H.265, MJPEG, etc.).

According to the IP camera parameters and the power of the DSP processor, the output signal will be encoded in a specific resolution and number of frames per second (FPS). A good quality recording without glitches requires at least 12 frames per second.

The signal then 'travels' to the recorder and/or the SD card inside the camera (or the computer recording app), where it is saved for future reproduction. This footage can later be retrieved as evidence or it can be streamed live on any screen connected to the recorder/smart phone via Internet or the computer network.

Camera is the most important component of the video surveillance system, because it is the source of all informations.

• Resolution – number of pixels on the screen during reproduction. Higher resolution is always better.
• Night vision – ability of the camera to record high quality images in low light conditions from various distances. Technology that is behind night vision is:
  
  • IR Light (Black/White picture)
  • Starlight technology which provides color picture even during the night.
  • Super Starlight technology, very similar to Starlight except it provides much clearer picture.
• Water resistance – degree to which the camera is waterproof
• Material – camera housing can be made of various materials, which determine their sturdiness
• Dimensions – ability of the camera to be inconspicuous in a given space or situation
• Video and audio analytic functionalities - besides basic video surveillance, this feature allows user to gather all kind of informations and receive more reliable, smart alarm detections. Example of informations it can provide is people/vehicle counting, detection of moving into wrong direction, scream or gunshot sound detection, etc..

This standard refers to how resilient camera is to outdoor elements, including humidity and water. IP is based on the international standard EN 60529. Each camera has an IP spec – an important feature to know when custom designing video surveillance system.

The first number (X) refers to the camera's dust-resistance, while the second one (Y) denotes its water/humidity-resistance (IP XY).

A big advantage of analogue video surveillance is its simplicity, especially because the analogue standard has been around for a while. Regardless of the brand and make, any camera can be connected to any recorder, provided that the PAL/NTSC standards are matched. In this case the installation is simple: camera and recorder are connected with a cable and then plugged into power source. Analogue cameras are also cheaper than the IP ones.

On the other hand, analogue video surveillance is less flexible and more difficult to upgrade because each camera needs to be connected to the recorder. Cabling is the main challenge here. Cables are normally laid out in the shape of a star, with each camera and its responding cable fitted at one star point. The situation gets complicated when there is more than one camera covering the same angle of the protected object. In this case, several cables need to run through the same cable tube. Aside from that, every recorder accepts a set number of cameras. When more cameras need to be connected, the only solution is buying an additional recorder.

Conversely, an IP recorder only needs connection with the computer network and a power source. Today's modern designs also allow these recorders to be fitted like any other multimedia device, without being housed in a server cabinet.

For example, according to the Rules of technical security, each camera needs its own power source – through a nearby plug socket or an additional powered cable – which increases the installation costs. Similarly, if PTZ cameras are used or if sound needs to be transmitted, more cabling is needed. Unlike all this, IP camera only requires a single inexpensive network cable. For IP technology to work, camera only needs connection to the nearest switch, not to the recorder itself. IP cameras are powered through the PoE technology, which means that they run on a network cable, without the need for additional power transformers. Aside from this technology, IP cameras can also be directly connected the power source – this allows for various outlet combinations depending on each specific situation.

When it comes to video analytics, it is almost impossible to compare analogue with IP cameras. This is because analogue cameras are only capable of transmitting video signal. There is no in-built video analytics in the way of motion detection, choosing between different modes of resolution, frames per second and sensitivity to light, or stopping unlawful access. On the other hand, IP cameras are able to function as a system for themselves. They don't even need the recorder. Most IP cameras have an built-in SD card slot or can directly record to NAS (network attached storage). They can even send alert in an email.