A Research And Implementation Of Transmission Of Flexible-rate Streaming Media File

Today, network bandwidth is still the biggest bottleneck in streaming media system applications, in order to meet the shortage of network bandwidth, many streaming media system find solution on the streaming media system architecture. However, in transmission for the same video content, most of traditional streaming media system use a single rate of the video file to provide services for all users, this rigid approach, ignoring the better part of the network performance group or some time.This paper aside P2P and other complex system architecture, concentrate on research streaming between two points. measurement the network performance between the two points in real-time , select the available contents of the file that that has transmission rate suitable for the current bandwidth, makes the plays to minimize network delay, the pair of network bandwidth utilization and transmission of the media to maximize content quality, to improve the streaming media system QOS. This paper research work carried out:First of all, research how to convection rate of multi-media files, media quality and grade of proposed division strategy, under the hierarchy of media quality, to reduce the video file size as much as possible when also ensure the quality of playback. On this basis of convection rate of multi-media files, discuss the organization and management of the media files on the disk, to achieve rapid positioning to the next need to send audio and video frames when context switching.Second, reseach how to measure the available bandwidth, after study of congestion control algorithm by reading a lot of research paper, using early warning of a delay in congestion control algorithm[23] that is suitable for streaming media applications, and combination of RTP/RTCP to calculation acquisition of the algorithm in real time, to obtain the current available network bandwidth.In realization of multi-rate file and available bandwidth measurement, focusing research on the multi-rate file transmission, when the bandwidth available changed, choose media content that the rate is meet the available banthwidth for transmission, to adapt to changing network performance, making the utilization of network bandwidth and to maximize the quality of media content that choose for transmission. Finally, research on variable coding parameters Filters play link with the dynamic mechanism, in the process of adaptive transmission media files to play when the resolution changes, use the "shortest" of the link length, to prevent "stop feeling" when the dynamic filters link happen.Experimental results show that the proposed multi-rate file transfer technology can achieve network bandwidth utilization and maximize the quality of the media play content, compared to traditional single rate file transfer in smaller network bandwidth, it also can reduce waiting times and reduce the buffering waiting time, this improve the streaming media system service quality.