Research And Implementation Of A Mobile Streaming Media Client

With the development of streaming media technology and mobile communication technology, mobile streaming media applications on the mobile Internet has become one of the most important and promising applications. Mobile streaming media applications have high performance requirements for network bandwidth, error concealment, real time, media synchronization, etc. However, because mobile network is not perfect and performance of mobile terminals is insufficient, these performance requirements cannot be perfectly met. Therefore, it is very important to study techniques of mobile streaming media client. This paper reviews two core techniques in mobile streaming media client, which are network transmission and audio-video synchronization, and then makes a deep research on these two techniques.Firstly, this paper proposes network transmission techniques for mobile streaming media client, which are adaptive buffering, network transport protocol adapter and limited networks traversal. According to user needs, network environment and performance of mobile terminals, adaptive buffering technique adaptively selects the file or memory buffering mode, using the designed media frame buffer pool to buffer the data for reducing the network jitter effect on the play. According to RTSP/RTP streaming protocol, network transport protocol adapter can adaptively select data transmission in two different ways, which are RTP OVER UDP and RTP OVER TCP. If the client is in LAN and cannot communicate with the streaming media server, the client can use one of NAT traversal techniques, UDP hole punching, to solve the problem. Among them, the work is focused on the design of the media frame buffer pool.Secondly, using buffering mechanism and traffic shaping of media frame buffer pool can efficiently achieve the intra-stream synchronization. Furthermore, this paper proposes an intelligent frame dropping strategy to minimize the loss of video information when the video frame buffer pool is full. For audio-video synchronization problems, this paper proposes a synchronization algorithm. The algorithm accurately calculates the audio playback time and combines with feedback regulation mechanism for the audio-video collaboration. Experiments showed that the algorithm can make the synchronous deviation less than 60ms, and synchronization performance is better than synchronization algorithm based on audio timestamp.Finally, using hierarchical, modular design paradigm in a low coupling, high cohesion, high scalability way, this paper develops a client on Windows Mobile phone platform, and test the client performance on the phone. Test results showed that the client can smoothly play streaming videos which resolution are 320x240, bit rate are 300Kbps and frame rate are 20fps, yet CPU utilization is less than 60%. The client's performance is outstanding and user experience is very excellent.