嵌入式流媒体客户端缓冲控制策略的研究

Research on buffer control strategies of embedded stream media client

围绕网络流媒体技术以及嵌入式环境的特点,阐述了流媒体传输控制中的平均速率、时延抖动、丢包率等各项重要控制参数,以及对这些重要参数进行测算的优化算法;提出了利用平均速率、时延抖动和辅助系数η这三个参数进行缓冲区长度估算的简化算法;采用分区预警阈值实施反馈,使得服务器端能够根据当前传输情况及时调整发送速率;并提出在客户端按照数据的重要性或优先级的不同来实施主动抛弃策略,从而节约流媒体客户端缓冲区资源,保证流媒体的QoS.同时进行了简单的软件模拟仿真分析.仿真结果表明,应用上述控制策略后明显节约了缓存资源.

Based on features of both the network stream media technology and the embedded system, the mean transmission rate, delay jitter, packet loss ratio and other major control parameters in the control protess of stream media transmission were discussed, and the optimization of measuring and calculating these important factors was given. The simplified method of estimating buffer length was proposed with the help of mean transmission rate, delay jitter, assistant parameter. A feedback mechanism was established by use of the divisional threshold values to make severable to receive current transmission condition and adjust its sending rate in time. The buffer control strategy of initiative discard at the client end was also given according to the data＇s levels of priority, so that buffer resources at the stream media client end could be saved and stream media QoS ensured. A simple software emulation analysis was carried out, proving that buffer resources are greatly saved through these control strategies.