Digital video recorders

Digital video recorders (DVR) and digital video servers (SVR) are appliances used in video surveillance. The DVR/SVR takes the analog video signals from multiple analog surveillance cameras and digitizes them. A processing engine encodes the video streams in digital formats such as H.264, motion JPEG, TI or proprietary codecs.
A DVR is designed to store and view this video stream locally. An SVR sends the encoded video to the larger security network using the TCP/IP protocol. Higher performance DVRs/SVRs also have analytical capabilities allowing for the automatic detection of motion, crossing of virtual fences, etc.
DVRs and SVRs are used to upgrade existing security systems, which are based on analog surveillance cameras. Replacing tape-based VCRs, the DVR/SVR automates the storage of surveillance data sheet and enables remote access to surveillance installations via TCP/IP networks. DVRs/SVRs typically have 4-, 8- or 16-input channels. With further integration, the channel count will increase to 32, 64 and beyond.