Abstract: A multi-object multimedia application allows simultaneous presentation of multiple multimedia streams；its synchronization control is complicated which includes transmission synchronization and presentation synchronization.However，existing synchronization schemes ignore the synchronization of presentation process and the requirement difference for synchronizing different media objects.This paper presents a scheme which controls the quality of presenting multi-object multimedia synchronously on the application level for video-on-demand mode.Based on utilizing multi-threshold buffer to implement intra-media synchronization feedback control，the secondary medias’ presentation rate is adjusted according to the primary media’s presentation time stamp so as to achieve inter-media synchronization presentation.The experiment results demonstrate that the proposed scheme improves the quality of synchronization effectively，and the performance of inter-media synchronization increases 28.45% averagely.

Key words: multi-object multimedia, synchronization presentation, inter-media synchronization, time stamp

摘要： 多对象多媒体应用允许多路媒体同时呈现，其同步控制比较复杂，可分为传输过程中与呈现过程中的同步。然而现有的同步方法忽略了媒体在最后呈现过程中的同步，也没有考虑各媒体对象之间的同步要求差异。针对以上问题，为视频点播提出了一种在应用层上控制多对象多媒体同步呈现质量的方法。在采用多级缓冲门限实现媒体内同步反馈控制的基础上，依据主要媒体对象的呈现时间戳，在每一个呈现场景内调整次要媒体对象的呈现速率，从而实现媒体间的同步呈现。实验结果表明该方案能够有效地提高同步质量，且媒体间的同步性能平均提高28.45%。

关键词: 多对象多媒体, 同步呈现, 媒体间同步, 时间戳