The Design And Implement Of RIA Streaming Media Video Sharing System Based On Flex

With the rapid development of Internet and web technology, web application system is becoming more and more popular, and user often want to accomplish more complicated interactive operation via a browser. However, the ability of traditional web application is always not powerful enough to satisfy people's requirements. As RIA (Rich Internet Applications) technology (Adobe Flex, for example) came into use, it provides people a new way to access all kinds of application over Internet. When developing a large-scale application which centers on data and contains a lot of complex user interfaces, RIA based solution is now becoming the first selection. As the stream media technology based on internet develops very fast, the development of RIA and widely usage of stream media technology offers a good environment for the realization of this RIA stream shared platform.The paper is mainly addressed on the RIA technology represented by Flex. First of all, the advantages of RIA compared with the traditional B/S structure are introduced. Then the paper gives a brief description to RIA and some kinds of common RIA development technology. Based on the above mentioned analysis, this paper is focused on the design and implementation of a stream media video sharing system. This system consists mainly of parts:foreground system and background system. The foreground system is the window for end users; it provides a lot of rich interactive functions. MVC design pattern is adopted in the design of foreground system, in which data and application logic, data view and the data operations are separated from each other and implemented in different entities. This model helps to realize partial update, less data exchange and rich user experience, and which is key points for video sharing system. The background system is mainly responsible for video transcoding and status monitoring. With respect to video transcoding, FFmpeg and AviSynth are combined to fulfill the task. To deal with the fluctuation of network bandwidth, each uploaded video clip is transcoded to one high bite rate stream and one low bit rate stream, and the system can select suitable bite stream automatically to end user according to available bandwidth. Another function of background system is to extract key frames from video clips for video content indexing. In order to get meaningful frames, face recognition technique and scene change detection are used.So far, the system designed in this paper has stably operated for six months, which proves the correctness and accessibility of RIA system. It also shows the advantages of RIA especially in Web application design and development.