Hypertext Transfer Protocol Hypertext Transfer Protocol (HTTP) - The communications protocol used to connect to Web servers on the Internet or on a local network (intranet). Its primary function is to establish a connection with the server and send HTML pages back to the user's browser. It is also used to download files from the server either to the browser or to any other requesting application that uses HTTP. Addresses of Web sites begin with an http:// prefix, however, Web browsers typically default to the HTTP protocol. For example, typing www.yahoo.com is the same as typing http://www.yahoo.com. In fact, only yahoo.com has to be typed in. The browser adds the rest. For both DVR’s in analog camera systems and IP camera systems, encoding is performed. Common encoding types are Motion JPEG and MPEG-4, while H.264 is a more advanced version of the latter, with even smaller data size requirement. As seen on this slide, Motion JPEG uses single frame encoding. This means that each frame in the video is encoded separately. This is essentially a video created by combining a series of complete JPEG picture files MPEG-4 and H.264, on the other hand, uses multi-frame encoding. A single “reference” frame is encoded just as Motion JPEG does for all its frames. However, only changes on a subsequent frame with respect to the reference frame is stored, meaning much of redundant data is neglected to keep data sizes concise. HTTP request Web pages HTTP response User’s PC HTTP Server