Research And Implementation Of Video Phone And Server Based On SIP

In recent years, the infrastructure of our country become better than before along with rapid development of modern communications and computer networks technology. As people’s living standard has reached a higher level, broadband internet has entered more and more families. People are likely to use various methods to communicate through network but not only voice-communication in the past, multi-media communication (such as video, voice, flash ant etc.) has already become an important part of people’s daily life. Meanwhile, with the development of our society and business, many companies like to setup several subcompanies in another city, thus a new method of communication is required. To meet the above requirements, the author was commissioned by An IT Company to develop a SIP based videophone system.This system uses SamSung S3C6410 chip as the core controller, running an embedded Linux system. It uses MFC hardware multi-media codec as the video codec, and supports for varous famous video codec algorithms such as H.263, H.264 and MPEG-4, the maximum frame rate is up to 30FPS. For audio, it supports many famous audio codec algorithms such as GSM, SPEEX and PCMU/PCMA, the minimum requirement of network is 20kps. Due to some bugs in Linux kernel provided by partner, there’re some problems in V4L2, in order to solve this problem, designed an application-layer double queue buffer. To meet the requirement of multi-window video display, this paper researched the diplaying technology under Linux and realized the dynamic video diplaying functionality using the hardware accelerator. Meanwhile, this paper researched audio combination technology, and realized the audio record functionality, user can record the conversation to a WAV file.In order to make this system more practical, this paper also researched the firewall technology, and conducted several experiments, then concluded that the OpenSIPS and STUN server can help ths system penetrates three kinds of farewall which is useful for most people.