面向TCP的流媒体传输编码码率自适应算法

An algorithm for encoding rate adaptive streaming media transmitting based on TCP

由于网络的时变性和异构性,以及在拥塞情况下的高丢包率,利用TCP传输流媒体数据是Internet流媒体分发系统提高流媒体分发质量的首选方案。由于TCP具有超时或错误重传机制,在网络拥塞情况下,难以保证高码率流媒体数据传输的实时性,因此提出一种面向TCP流媒体传输的编码码率自适应算法(TCP_RA)。该算法根据流媒体发送应用层缓冲区读写指针差值调整流媒体发送端的编码码率适应网络带宽的变化。仿真实验对比分析了该算法与基于UDP之上TFRC协议的流媒体传输码率自适应算法在流媒体传输质量上的差别。结果表明,该算法在网络环境较差的情况下有效地提高了流媒体传输质量。并且该算法容易实现,值得推广。

Because of the network＇ s time-varying and heterogeneity, and also the high probability of packet loss in congested network, transmitting media streaming over internet by TCP is a preferred scheme, which can improve the media streaming QoS. But due to the TCP retransmission for error or time out packets, in the congested network, it is difficult to provide real time transmission for high bit rate media streaming. This paper proposes an encoding rate adaptive media streaming transmitting algorithm （TCP_RA） based on TCP. It adjusts the media streaming encoding rate according to the difference between reading and writing points in the application layer buffer, in order to suit the network bandwidth＇ variety. It compares the difference for rate adaptive media streaming QoS improvement between TFRC and TCP_RA by simulation in NS2, simulation results show that TCP_RA can effectively improve the media streaming QoS in bad network environment. The algorithm is easy to implement, so it＇ s worth of popularizing.