SMIL多媒体时间同步参考模型的提出和实现

AN IMPLEMENTATION OF SMIL TIMING REFERENCE MODEL

SMIL首先将媒体对象组织成由时间控制的树结构形式,通过进一步完善和扩展,最终扩展成图。图结构的复杂度保证了SMIL控制效果的多样性。实际上,SMIL的主要功能都是建立在一个基于XML环境的时间同步模型上,该时间同步模型可以理解成一个三层的系统。本文提出了定义在系统层的SMIL时间同步参考模型。该模型重点描述如何由外来的交互事件来引发所谓的时间控制命令以达到交互控制的效果。根据处理内容的不同,整个SMIL时间同步参考模型基本可以分为四个功能模块预取准备模块,同步时间依赖关系模块,确定时间表模块和同步时间控制模块。

The SMIL timing model integrates media o bjects as a tree spanned by timing,which can also be extended to a graph.The gra ph structure can guarantee the validity of SMIL control.Actually,SMIL constructs the timing model based on a XML environment,which can be thought of as a three- layer system. This article presents a timing reference model of SMIL.The reference model of SM IL is defined at the system layer,which focuses on how to get the timed control command from SMIL basic synchronization(sync arc)and extend interaction.The refe rence model has four functional modules:prefetch module,timing dependency graph module,resolved times module and timing control module.