Recording and/ or monitoring of surveillance footage is done through a device known as a DVR (Digital Video Recorder) in the case of Analogue and HD Analogue CCTV or an NVR (Network Video Recorder) in the case of an IP based CCTV Solution.
Analogue devices typically are “embedded” DVRs meaning you purchase a recording machine manufactured by the suppliers. These embedded machines come in 4, 8, 16 and 32 Channels i.e. 1 channel per camera.
Network Video Recorders (NVR) can either be embedded recorders with their own software or PC / Server Based typically using 3 rd party software.
Currently embedded NVRs are available in the following sizes – 8, 16, 32 and 64 Channels. Embedded NVRs do however have their limitations in terms of processing power and analytical functionality but they generally work out considerably less than a PC/server based machine with 3 rd party software.
Typical terminology you would encounter on both a DVR and an NVR would include:
FPS (Frames Per Second) or IPS (Images Per Second)- “Real Time” is generally considered 25 FPS. For example the typical 8 Channel DVR would be 200FPS. This is the total frame rate of recording available on the machine thus 200 frames over 8 channels = 25 FPS per camera or “real time”. If an 8 Chanel DVR only had 100 FPS, the maximum recording if all 8 channels were populated, would be only 12.5 FPS. It is quite uncommon these days to find a DVR that cannot record at the full frame rate across all channels.
I/O – Input Output Board: If a DVR has I/O available then the DVR can be utilised to trigger actions or be triggered if an action occurs e.g. if the intruder detection system is triggered, start recording all channels.
Motion Detection: Most CCTV Cameras either on the camera or DVR (or both) have motion detection technology built in. What this means is that the DVR will only record if motion is detected. This greatly reduces the storage requirements of your system and thus the overall cost of the solution.
H.264 or MPEG-4: is a video compression format that is currently one of the most commonly used formats for the recording, compression, and distribution of video content.
POE: Power Over Ethernet – Some embedded NVRs do come with some built-in POE on board the machine. At present, the average ratio is 50% of the ports are POE.
SATA Hard Drive(HD): This simply refers to the hard drives which are installed in the NVR or DVR to record the CCTV footage.
Hybrid – Some manufactures have brought out “hybrid” recorders which can record both analogue and IP cameras concurrently. The average Hybrid machine is a 32 Channel machine which is able to record up to a maximum of 16 Analogue cameras and the balance IP cameras. However, if only 10 analogue cameras are on the system, you would be able to add 22 IP cameras.