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移动网络中,不仅信道的质量具有时变性,而且不同用户的终端具有异构性.这就要求移动网络中的视频服务具有码率自适应性.针对自适应流媒体传输,提出一种全新的基于缓冲区下溢概率的码率自适应算法.虽然当前信道的质量是不可观测的,但是信道质量的变化会反映在缓冲区的变化上.因此,可以利用缓冲区下溢概率来表征视频码率和信道吞吐量之间的不匹配程度.我们构建了一个有约束的优化问题,即在保持下溢概率在一定范围内,最大化视频质量.同时,我们提出了基于大偏差原理的下溢概率估计模型及相应的码率自适应算法.最后,通过原型系统实验,我们验证了该算法在保证较低播放中断率的同时,能够提高视频质量.
In mobile networks, not only the quality of the channel is time-varying, but also the heterogeneity of the terminals of different users, which requires that the video services in the mobile network have the bit-rate adaptability.Aiming at the adaptive streaming media transmission, a new Rate Adaptive Algorithm Based on Buffer Underflow Probability Although the quality of the current channel is not observable, the change in channel quality is reflected in the change of buffer, so the buffer underflow probability can be used to characterize the video code Rate and channel throughput.We constructed a constrained optimization problem that maximizes video quality while keeping the underflow probability within a certain range.At the same time, we proposed an underflow based on the principle of large deviation Probability estimation model and the corresponding rate adaptive algorithm.Finally, through the prototype system experiment, we verify that the algorithm can improve video quality while ensuring lower playback interruption rate.