Research And Implementation Of Mobile Video Conference System

With the continuous development of science and technology,people all want to improve the work efficiency,the traditional telephone,fax gradually become unable to meet the needs of the growing exchanges,people need a technology to have meeting quickly.In this demand,the mobile video conferencing system can meet people's needs,people can make a video conference through the mobile terminal.SIP protocol is a kind of control protocol for multimedia session,it is simple,flexible and easy to extend.It has been paid more and more attention in the field of video conference.Android operating system is an open source mobile operating system and it has the highest market share of smart phone operating system.With the popularization of 4G communication technology,the network can be able to meet the requirement of high quality audio and video communication.Based on the above technical features,this paper designs a mobile video conference system based on SIP protocol on android mobile terminal.The system uses the H.264 format to carry out the video coding and decoding.The system uses the open source FreeSWITCH server as the SIP video conference server,and this paper focuses on the mobile client design and implementation.The mobile client uses SIP protocol to control and manage the session,uses the session description protocol to negotiate the multimedia capabilities between the two parties,uses the real-time transmission protocol to carry out the transmission of multimedia stream.About the audio and video codec,this system use Android NDK development technology to call the third party open source codec(Speex,x264,FFmpeg)to carry out the audio and video codec.The multimedia module uses the AudioRecod class and AudioTrack class for audio recording and playback,uses the Camera and SurfaceView for video recording and displaying.As the same time,this paper studies echo processing technology and the synchronization of the audio and video.The mobile client uses a modular design,so that the system has a good scalability.Finally,through functional testing and performance testing,the client can make clear audio and video calls,it has met the requirements of the video conference client.