| With the rapid development of technology of network, the communications between the video monitoring systems have become a very import issue. Session initiation protocol is a signaling protocol. With supporting the SIP, terminal can receive the information from this monitoring system. If the video monitoring terminal was implemented based on SIP, the monitoring system would become an open system, thus the surveillance can be performed at any time and place.This paper studies key technologies about video monitoring system based on SIP and design a video monitoring system based on SIP. As video monitoring has a high demand on real-time, the design of video monitoring system based on SIP improves the Linux kernel by RTAI to improve real-time. This paper introduces how to construct embedded system of video monitoring based on SIP and describe how to implement video capturing by Video4Linux interface, implement video encoding based on MPEG-4 by Xivd. As for the selection of coder, as there are lots of coders and decoders, to make the video processing adapt to various coding and decoding ways and is easy to extend ,the article use an oop method to make all operations on coders and decoders become unified. The video monitoring system based on SIP designed by this paper use RTP to implement real-time transmission and gives a detailed discussion about MPEG-4 segmentation and the generation of RTP packet. To not impact system's real-time, video capturing,encoding and transmission are implemented by multi-threads. The article gives a design about SIP protocol stack in the last part which used by video monitoring system based on SIP .It extends SIP by add a new request message called CONTROL, which can be used to modify parameters of video capturing device.The article presents a basic solution of embedded video monitoring system with SIP, which make it possible to communicate betweens other system based on SIP and this video monitoring system. The experience and solution summarized in this paper would be of great referenced values for both the monitoring system and the SIP based on applications. |
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