Video servers enable distribution of video signals over networks including local area networks (LANs) and the Internet. They allow access to video by many users simultaneously and often include features such as audio compression and streaming, control of external devices such as cameras and VCRs, and accessibility via standard web browsers. Video servers can operate in monochrome or color. Monochrome is black and white, or grayscale; the image is presented in black, white, and grayscale. The range of colors is generated with varying combinations of different discrete colors. One common technique is sensing the red, green, and blue components (RGB) and combining them to create a wide spectrum of colors.
Important performance specifications to consider when searching for video servers include number of video inputs, maximum frame rate, and video storage capacity. Number of video inputs refers to the number of inputs available; inputs can include cameras, recorded video sources, etc. It is the total of all types of input connectors. Maximum frame rate is the number of frames that can be transmitted or broadcasted per unit time, typically frames per second. Video storage capacity is the capacity of digital video storage on a hard disk or other medium. In cases where this specification is dependent upon the video format or resolution being used, the maximum possible storage is given.
Interface and Protocol Specifications
Interface and protocol specifications to consider when searching for video servers include LAN or WAN technology, communication protocol, and control or management interface. LAN or WAN choices include 10baseT Ethernet, 10base2 Ethernet, Fast Ethernet, ISDN, Token Ring, Novell, and wireless. Communications protocols that video servers can employ include TCP/IP, HTTP, PPP, RTP, VDP, RSVP, and RTSP. TCP/IP stands for Transmission Control Protocol / Internet Protocol. HTTP stands for HyperText Transfer Protocol. PPP stands for Point-to-Point Protocol. RTP stands for Real Time Protocol. VDP stands for Video Datagram Protocol. RSVP stands for Research ReSerVation Protocol. RTSP stands for Real Time Streaming Protocol. Control or management interfaces for video servers can be RS232, RS422, RS485, web-based, and wireless.
Common features for video servers include audio capability, switching capability, e-mail capability, Microsoft IE or Netscape compatible, event detection or triggering, password security, and external device control.