Session Initiation Protocol, SIP
Session Initiation Protocol SIP: The Session Initiation Protocol is formulated by the Internet Engineering Task Force (lETF: Internet Engineering Task Force) and is a framework protocol for multi-party multimedia communication. It is a text-based application layer control protocol, independent of the underlying transport protocol, used to establish, modify and terminate two- or multi-party multimedia sessions on the P network.
This protocol is often used in the video networking platforms of Safe City and Xueliang Engineering.
Media Server, MS
Media Server is mostly used in large-scale video networking projects. Provide real-time media stream forwarding services, coal storage, historical media information retrieval and on-demand services. The media server receives media data from devices such as SIP devices, gateways or other media servers, and forwards the data to other single or multiple SIP clients and media servers according to instructions.
Wide Dynamic Technology, WDR
Wide dynamic technology (WDR): The so-called dynamic refers to the dynamic range, which refers to the range of change of a certain characteristic that can be changed. For the camera, its dynamic range refers to the camera’s ability to adapt to the light illumination in the shooting scene. Quantify its index and express it in decibels (dB). For example, the dynamic range of an ordinary CCD camera is 3dB, and the wide dynamic range can generally reach 80dB, and the good one can reach 100dB. Even so, compared with the human eye, it is still much worse. The dynamic range of the human eye can reach 1000dB, and the more advanced is that the eagle’s vision is 3.6 times that of the human eye.
So what is the concept of super wide dynamic and super wide dynamic? In fact, this is all artificial. Some manufacturers add a super in order to distinguish it from other manufacturers or to show their own wide dynamic effect. In fact, there are only so-called first and second generation differences. In order to improve the dynamic range of their own cameras, early camera manufacturers adopted the practice of double exposure imaging and then superimposed output. First expose the brighter background quickly to get a relatively clear background, and then slowly expose the object to get a relatively clear object, and then output the two images superimposed in the video memory. Doing so has an inherent disadvantage: one is that the camera has a delay in output, and there is serious smearing when shooting fast-moving objects. The other is that the sharpness is still not enough, especially when the background illumination is very strong and the contrast between the object and the background is large, it is difficult to image clearly.
Wide dynamic range was especially popular in early analog systems and digital systems. It was regarded as an important product selling point in the early days. In the A era, this technology has not been eliminated.