中文摘要：

在集中式多媒体音频会议中，混音算法决定了其混音输出语音质量的高低，而混音算法的实现要依靠同步混音转发机制的支持。对Perkins提出的混音循环缓冲区进行分析，提出一种适用于集中式多媒体音频会议系统的实时同步混音转发算法。该算法通过设置多个循环混音缓冲区，并对其实施同步控制来实现音频数据的混音、转发功能，并利用反映操作系统调度情况的声卡缓冲区数据长度确定每次混音处理的数据长度，以减轻操作系统调度对混音的影响。实验验证了此算法的可行性和稳定性。

英文摘要：

The audio mixing algorithm determines the quality of the mixing voice in the unicast based centralized multimedia conference system. However, the implementation of the mixing algorithm is based on the backup of synchronous audio mixing and transmitting mechanism. The circular mixing buffer （CMB） proposed by Perkins is analyzed, and then a real-time synchronous audio mixing and transmitting scheme is presented. This scheme is achieved by setting multi-CMBs and controlling them synchronously. The length of data used for mixing is decided by the one of data storing in the soundcard buffer which reflects operating system （OS） scheduling. This can alleviate the influence of OS scheduling on the audio mixing operation. Experiment results manifest that our scheme is feasible and steady.