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 It is a hot topic widely discussed among manufactures, end-users and media which one will be more suitable for future video surveillance system between HD-SDI cameras and Megapixel IP cameras as both HD-SDI cameras and IP cameras can reach megapixel resolutions, and both are hot products in video surveillance market.

The article will analyze and compare these 2 products from 6 aspects including function, capacity, cost, user-friendly and reliability.
Network cameras can achieve the video capturing, encoding, video stream network distribution and storage, embedded Web page contains video applications, and intelligent network cameras even own intelligent analysis functions. Consequently, network camera has all the core features of the video surveillance system, so video surveillance system, in theory, can be constructed by only using the network cameras. Some people might not agree with this conclusion: If the network camera can build the video surveillance system independently, what are NVR and VMS for? The reason of NVR's existence is due to storage capacity shortage of SD cards of network cameras, and potential risk of SD card storage safety. As capacity of the SD card keep increasing and network security technology developing, there will be revolutionary changes of the video storage way in the future. The VMS system's main function is to centralized management of devices. This function can be distributed and deployed to network cameras while CPU performance getting higher and higher and the development of cloud computing technology. Therefore, in the network camera based video surveillance systems, network cameras are the core of the systems.
On the other hand, The function of HD-SDI camera is only video capturing, which is identical to the traditional CCTV analog cameras, and only change is the image resolution improved from D1 to mega pixels . So in the HD-SDI cameras based video surveillance system, HD-DVRs is the core of this systems.

HD-SDI camera's advocates will emphasis 2 points: image quality and latency of live video.
HD-SDI Cameras' live video has not been encoded, the image quality is better than network cameras' in principle, but it is only has mathematic meaning. As there is limitation for human eyes to identify image details, so there is almost no difference between megapixel network cameras and HD-SDI cameras.
As for latency of live video, it basically doesn't exist for HD-SDI cameras. While for network cameras, the theoretical latency of network cameras at 30fps is 140ms, and 60fps is only 70ms. However, in actual applications latency of network cameras is normally more than one second because of unstable network, If network camera developers pay enough attention to this problem and finally reach this theoretical minimum latency, then there is no practical difference between IP cameras and SD-HDI cameras.