The Research And Development Of Video Conference Terminal Based On SIP

With the rapid development of the Internet, the analog signals which is used in traditional video conference to transfer video and audio data is replaced by digital signals with high quality of signal transmission and strong anti-interference ability for its poor anti-interference ability. SIP protocol has been widely applied in video conference for its advantages of simplicity, free access and good expansibility.The Centralized framework and distributed framework of video conference are analyzed. The centralized architecture is used for the scale of the video conference to implement the function that the Internet protocol network camera as a video conference terminal could communicate with other SIP phones in the market by the application of SIP protocol. Based on the hardware platform of DM36 x and embedded Linux operating system, the video conference terminal based on SIP has been developed to send and receive SIP message and streaming media data. The SIP session control module has been designed using HTTP protocol, web server in Internet Protocol Network Camera, the inter process communication and SIP stack to implement parameter configuration, registration and parsing and processing SIP messages. The media processing module has been designed using RTP protocol, socket and circular buffer to transfer video and audio data and make the output speed of audio data sent by media processing module match the input speed of audio data put into decoding module.A web server and SIP phone have been set up in local area network for functional test. The function of parameter configuration, registration and paring and processing of SIP message have been implemented, which demonstrates that the SIP session control module is designed correctly. The function of media data transmission has been implemented, which demonstrates that the media processing module is designed correctly. A conclusion is drawn that it could realize point to point video conference.