R&D Of Local Area Wireless Image Broadcasting And Interactive Terminal Based On MPEG-4Technology

With the rapid development of the embedded technology and streaming mediatechnology, image communication based on the intelligent embedded system is also muchfavored. The advantages of the embedded processor which are strong functions, small sizeand low cost make it occupy a broad market in network communication, video surveillance,remote education and other fields. Due to the local wireless narrow bandwidth constraints, itis necessary to compress the original data to improve the instantaneity and efficiency ofimage transmission.Based on the MPEG-4video codec standard, Wi-Fi local area wireless communicationtechnology and the streaming media real-time transport protocol, we have designed a set ofvideo capture, compression, real-time transmission, real-time display, automatic storage andplayback functions in one image broadcasting and interactive terminal which uses ARM11asthe core of the embedded hardware and Linux operation system as the software developmentplatform.With the teaching application background, this subject has realized several functionswhich are classroom setting, roll calling, broadcast teaching, interactive Q&A and storagereviewing. Image communication between the terminals has been formed without wirelessrouting. Therefore, the ad-hoc network can be achieved according to the number of theterminals under current network. Based on the transmission characteristics of RTP protocoland the inter-frame processing of MPEG-4compression standard it has realized selectivelydiscarding and processing of the packet loss to ensure the reduction of the current scene andthe efficiency and reliability of the image communication. It has drawn up an explicit schemeof the functional modules for this system and has designed a man-machine interactive Qtgraphical interface based on the actual function requirements. By reading a large quantity ofliterature, this thesis has analyzed the feasibility of the general scheme and has put forwardthe solutions to the technical key points and difficulties for this subject.The main content of this thesis has two aspects which are hardware design and softwaredesign. Hardware implementation presents the design of board circuit schematic and PCBlayout in detail. Software design mainly expounds the construction of system softwaredevelopment environment, including arm-linux-gcc/g++cross compiling environment, NFSnetwork file system and the transplant of Qt GUI, driving and configuring each module in Linux, image capture based on V4L2API, implement of video codec based on MPEG-4,application of streaming media protocol and design on Qt graphical interface.This system has got optimal parameters by debugging and testing largely. Not only has itrealized image broadcasting and interacting under local area wireless network environmentbut also it has implemented classroom setting, roll calling and playback functions based onthe research background and expected requirements. It can realize switching smoothlybetween the user functional interfaces of this system. With good quality and high speed of theterminal image transmission which meet the requirements of instantaneity and stability, thissubject has achieved the desired research goals.