| There are many drawbacks in traditional meetings or classrooms.One is that the listener may not see the content shown by the speaker because of his own vision and other reasons,and there may be the problem that he can not record the content in real time.The second is that the speaker of the traditional meeting or classroom model is only a single meeting sharing his speech content to everyone,or the lecturer will share his own ideas.Law and knowledge points can not be instilled into students to achieve the purpose of sharing and interaction between listeners and speakers.The main research significance of this topic is to design a system which can realize multi-person mobile image information exchange under LAN by using the mobile Android handheld terminal which has emerged in recent years,which combines embedded hardware platform and Internet technology.Teachers or leaders can intercept the PPT files that be talked about and send them to the handheld terminals of all listeners under LAN in real time.On display,the listener can also send the files of the local library to the server terminal held by the teacher or leader through the handheld terminal for sharing with other listeners.The main research work of this system includes instant image pixel acquisition,image file reconstruction,FTP server construction,the upload and download of image file,user database design,UI design,communication under C/S architecture,etc.The server can intercept and upload real-time images to FTP server.Each client can access FTP server by login with account password.The files on the FTP server can be uploaded to the server for sharing with other terminals,which has certain practical value and can be applied in small-scale multi-person interaction scenarios such as meetings,teaching and so on.Its innovation lies in that the whole system works in the LAN of the Ad Hoc Network,and the image files are not processed by the cloud,so the file data is safe and reliable,and can be used in encryption occasions.Secondly,the image files are saved on the server in the form of PNG files rather than the pixels of the image files are transmitted directly on the handheld terminals,so there will be no adaption beween the handheld terminals of different screen sizes Questions.All handheld terminals under the system are based on Android system,without additional hardware circuits,the overall architecture is relatively simple.The server-side hardware of the system is a TECLAST P85 tablet computer,which is equipped with RK3066 ARM Cortex-A9 dual-core processor.The memory chip is DDR3 in1 G space.It can be connected with external projector through HDMI or WIFI wireless connection for screen projection.Each client hardware can use various handheld terminals(mobile phones or tablets)with Android 4.X version.The system has no special requirements for the system parameters of the handheld terminal,and has a wide range of application conditions.The projector uses Epson's CB-S41.Because the projector only enlarges the server screen,there is no special requirement.The test of the whole system shows that there will be individual time difference in the process of intercepting and uploading image files of different sizes on the server side,but after the adjustment of compression algorithm,even if the image color difference is large,the image synchronization process between the server and the client can be realized in 5s,at the same time,the integrity of image restoration degree can be guaranteed,which conforms to the majority of teaching or meeting scenes.In the process of synchronization,the client can also download the corresponding image files by local cache,and at the same time,the historical files can be viewed by FTP server.The whole system includes not only the interactive parts of functional modules and UI,but also the expansibility,robustness and maintainability of APP development,which meets most of the practical requirements. |
