Research Of Device Discovery And Frame Buffer Of Terminal System

With the development of embedded technology, network technology, and automotive technology, vehicle information entertainment system has become the new trend of modern automobile. Meanwhile, Android-based Smartphones are more widely used. It is becoming a hot spot that how to make drivers seamlessly connection and control mobile phone application through touching the screen of vehicle information entertainment system’s monitor, improving availability of vehicle services, such as telephone, navigation, social activities and music. The research in this paper is based on VNC (Virtual Network Computing), whose terminal mode system which is divided into mobile server and vehicle client could meet this demand. This paper aims at the research of mobile service.The study object of this paper is mainly about the problems that exist in the process that VNC applies to vehicle system. At the beginning, we select a open source VNC software for a in-depth research, understanding its structure and principle. Then we combine practical demands of terminal mode, analyzing the existing VNC system problems. Those problems include:(1).user must manually input the IP address and port information which is very cumbersome for the normal user, decreasing the user experience;(2).The refresh rate is not very well, which leads to the vehicle terminal system can not be timely synchronized with the mobile phone in the screen refreshing. At the same time, The operations are not fluent enough, decreasing the user experience;(3).The existing VNC system cannot achieve sliding touch.According to these problems, we have made many researches on device discovery and frame buffer server, raising related solutions. It includes:Firstly,for question1, we have two solutions:IP fixed method and integrated UpnP method. Finally, clients would not have to input the IP address and port information when they connect to the server;Second,for question2, we have deeply studied screen spot capture technology, pixel conversion algorithm, image transformation algorithm and send update mechanism. And we make some amendments to the RFB(Remote Frame Buffer) to adapt this system. In order to achieve rapid detection of the changing screen information and make full use of limited bandwidth, we propose to split the screen as many small rectangle, which achieves the goals that each time it only sends the changes of regional, and it further reduces the amount of data sending, making pixel format conversion. In order to send updates in time, we use the strategy that server actively sends updates. At the same time, when the screen sizes of both server-side and client-side are not matched, we use bilinear interpolation algorithm for image transformation. In addition, for many clients, we analyze the existing concurrent processing technology, and we eventually use the dynamic thread pool for concurrent processing. In the end, compared to the open source VNC system, the server-side of mode terminal that implemented in this paper has been some improvement in performance;Thirdly,for question3, through the study of input event handling in Linux, we achieve this system to support for sliding touch events.At last, this paper gives the test results of terminal services mode, and summarizes the work. For the deficiencies of the system, we put an outlook on the next step.