一个多媒体数据库系统的时间同步控制机制

Mechanism of Time Synchronous Control in a Multimedia Database System

对象合成Ｐｅｔｒｉ网可方便地描述多媒体对象的时间同步关系．在讨论多媒体数据库的时间同步问题后，给出可用于多媒体数据库中对象间同步关系的描述与控制的一个具体的实现方案．它涉及三方面内容：（１）如何用对象合成Ｐｅｔｒｉ网描述多媒体数据库中对象间的时间同步关系；（２）给出存放合成对象Ｐｅｔｒｉ网的数据结构；（３）给出按ｐｅｔｒｉ网所描述的同步关系演示多媒体对象的展示算法．

The time sgnchronization of multimedia otject can be convenientty descrited by .Petri Net of object composition. After discussing the time synchronization of multimedia database an implementatition plan by which the object sychronization in a multimedia database can be descrited and controlled is given. The plan includes (1) how to describe the object synchronization in multimedia database by using Petri Net of object composition; (2) data structures for storing Petri net of object composition; and (3) an algorithm for demonstrating multimedia objects in the light of time synchronizing relations described by Petri Net.