Implementation And Optimization Of Mobile Streaming Player Based On Symbian OS

With the rapid development of mobile communication technique and multimedia compression technology, mobile streaming media technology, such as mobile TV, video surveillance etc, is widely accepted by people.The implementation of mobile streaming media client on Symbian platform is based on the analysis of the transport characteristic of wireless streaming media and h.264 video decoding technology. Followed The 3rd Generation Partnership Project mobile streaming system framework, the player contains three modules: network transmission module, audio/video decoder module, audio/video play module. The network transmission module makes use of asynchronous functions as well as the event-driven of active object to administrate requests and receives of multi-channel network data: RTSP uses TCP active object to control the real-time transmission in application layer; RTP receives and splices streaming data asynchronously by using UDP active object; RTCP transmits status report periodically by means of UDP active object to control the flow and congestion. The audio-video decoding module decodes AAC/AMR-NB audio frame and H.264 video frame that spliced by RTP. The direct screen access technology and multimedia framework technology are adopted by audio-video playback module to output audio and video, whose play speed are adjusted according to timestamp to realize audio-video synchronization. On account that the mobile terminals in Symbian platform are weak in processing ability and limited in storage capacity, the key of this paper to make streaming media play fluency is optimize the H.264 video decoder and efficiently utilize of buffer.Because the access of files in CMWAP is only through HTTP proxy, it's necessary to optimize the network module. The player transmits HTTP request to mobile agent server, receives audio-video data and control the flow actively to prevent buffer overflow. A series of measures such as transmission data parallelly, requesting data dividedly, increasing the index information and introducing transfer server are taken to make streaming media play fluently in CMWAP. When it is installed on S60 2nd/3rd and tested in the real GPRS/EDGE network, the client application meets the requirements of the design.