Dvr is digital video recorder,Relative to the tradition of the video camcorder, the use of video disk, we often referred to your video disk, also called dvr . it is a series of images are stored in computer system, with a long time to get a video, audio, remote monitor and control functions, dvr get the vcr and the division, head shots, the network transmission control and wait for five types of functions in one, With a device will be able to replace analog systems of the equipment function, and in the price was an advantage. dvr use of digital recording, the image processing, storage and retrieval, backup, and the remote control, etc, are far superior to impersonate the monitoring equipment, dvr of the television monitoring system development, is currently in the tv monitor system of primary products. Currently in the mainstream dvr the compression techniques have mpeg colors, mpeg -4, h. 264, m, the jpeg and mpeg -4, h. 264 is the most common form of compression ； from compression card points have a soft down hard and compressed two soft down was cpu with large, not all of a real-time video displays and, gradually be eliminated from the camera a compressed ；enter into a road, number 2, 4, 6 and 9 of the road to the road, 12, 16 and 32 way, even more, Generally speaking, in the structure can be divided into two categories based on a pc ： of the pc dvr and out of the pc of embedded dvr. here we speak of the pc dvr and embedded dvr.