The Design And Implementation Of Mobile Video Conference System Under Unified Signaling

With the rapid development of the mobile internet,the continuous improvement of hardware performance of mobile electronic devices,the more and more perfect network infrastructure,we have been transiting from traditional 2G and 3G eras to 4G and 5G eras,which provides a better hardware foundation and have brought mobilization and intelligence to video conferencing systems.At the same time,with the great development of commercial globalization,the diversified demand for mobile video conferencing is also increasing.Compared with traditional video conferencing,mobile video conferencing is more complicated in its needs of hardware devices,network conditions and work environments.Therefore,research and implementation on mobile video conferencing has been becoming a hot topic.Although there are many commercial video conferencing vendors,due to the limitations of internal protocols,their scalability entirely depends on vendors,so that it's becoming more and more difficult to customize and expand the diversified needs of mobile video conferencing,so,it needs more open and excellent audio and video technology.WebRTC(Web Real-Time Communication)provides almost all core technologies including video capture,encoding,transmission and so on.Its free open source and cross-platform support facilitates the development and customization of video conferencing.Based on WebRTC technology and features of mobile terminal,this thsis designs and implements a mobile video conferencing system.Mobile devices in Internet are complex and differs in performances,moreover,the upper limit of video codec processing is very low,if there are too many participants in one video group chat,P2P(Peer-to-peer)case the number of video streams to increase exponentially,which is exactly not suitable for multi-person meetings.The network environment of the mobile device is complex and fluctuates greatly,so that the video quality at the receiving end is unstable and different,as well,the video display is unstable.When video conferencing interoperates due to commercial cooperation,video conferencing based on WebRTC technology cannot be interoperable because of the different protocols of the signaling control layer.Main contribution of the thesis are as following:(1)Design and implement a single video chat and a group video chat module based on WebRTC audio and video technology.By the analysis of the video group support scheme,the video group chat function in mixed flow model is designed and implemented.Then,the communication quality of the video conferencing in network fluctuation and bandwidth fluctuation is improved by processing video communication under the circumstances of complex network,adopting seamless communication network,accessing multi-operators and optimizing rate control algorithm,etc.(2)Design and implement the image super-resolution reconstruction algorithm for mobile video conferencing.RAISR(Rapid and Accurate Image Super Resolution)algorithm is introduced in the SDK design of the mobile terminal to improve the reconstruction speed through GPU operation and effectively improve the video quality of low bandwidth.(3)Design and implement a unified signaling gateway for different protocol conversions.For the interworking requirements between mobile video conferencing,we researched the mainstream signaling protocols,such as SIP,H.323,XMPP and so on,and realized the video intercommunication between different signaling clients through unifying signaling converting among different signaling gateway.(4)Through testing and analyzing on our video transmission quality of video conference,monitors and verifies data such as bandwidth,code rate and packet loss,etc during video call,It shows that mobile video conference has stable video communication under complex networks,and the packet loss rate is less than 1%.RAISR algorithm is used on videos,the single image reconstruction speed on the i Phone 6 device is40 ms.Experimental data shows that the RAISR algorithm consumes less mobile resources and can meet the real-time requirements while improving video quality.The signaling connectivity and connectivity time under the communication signaling gateway are tested and experimental results show that the connectivity success rate is above 95%,which can be applied to the signaling interworking of the mobile terminal.