VCR-based Analog CCTV – Analog cameras are connected to a video cassette recorder which stored video on cassettes. All signals and devices were analog. CCTV stands for closed circuit television. In addition to the VCR, a quad/multiplexer device enabled views of four separate images on one monitor or record more cameras on one VCR. The quad/multiplexer can assign a given camera to specific monitors, enabling control-room operators to view multiple scenes simultaneously on separate monitors.

DVR-based CCTV – Arriving in the mid-1990s, this system connected analog cameras to a digital video recorder (DVR), which became the recording medium instead of the VCR. Analog feeds were digitized and compressed for storage. This eliminated the need for taped cassettes and users could search recorded video more quickly. Additionally, the DVR enabled quad/multiplexer functionality.

Network DVR Analog CCTV – As time moved on, the DVRs featured an Ethernet port for network connections. This made possible both remote viewing on PCs and system operation. In these systems, the main components are analog cameras, DVR, network switch and PCs in addition to coax and twisted-pair cabling. Although it represents a technological advance, the DVR had limitations regarding maintenance, upgrades, virus protection, etc.

Video Encoder-based Network Video Systems – An open platform, this system uses a video encoder (or video server) to digitize and compress video sent by analog cameras. Video is sent over an IP network via a network switch to a PC server. This server runs the video management software or VMS and handles the recording function with better scalability.

Network Camera-based Video Systems – An entirely digital system, this development uses IP or network cameras, which digitizes the images within the camera; this digital format remains throughout the system to deliver strong and consistent image quality. Video is transported over an IP network using switches. The PC server handles recording. Video analytics, megapixel cameras, wireless functionality, ability to pan, tilt, zoom and other functions are accessible over IP.

Video Surveillance as a Service (VSaaS) – An on-demand, cloud-based video management system (VMS) compatible with a range of analog and IP security cameras. Unlike traditional systems, VSaaS does not require installation of an operating system, application software or the configuration of routers and cameras. There is no need to set up storage servers. Users can connect most existing cameras to a small bridge appliance, which enables connection to the cloud-based VMS. Cloud and on-site recording are available.

Note: Web cameras are typically used for such applications as Teams, Zoom or Skype video. These are not the same as IP Network or analog cameras. They don’t have recording functionality. They operate only when connected to a PC or laptop. Software must be installed on the PC to run the camera.

Sources: 1) Bulleted information based on Intelligent Network Video by Fredrik Nilsson of Axis Communications, CRC Press, Taylor & Francis Group, 2009. Updates based on August 2020 interviews with Advanced Global Communications. 2) Video Surveillance as a Service (VSaaS) based on 2019 interviews with Advanced Global Communications.