扩展时间流Petri网多媒体同步模型

EXTENDED TIME STREAM PETRI NETS: A MULTIMEDIA SYNCHRONIZATION MODEL BASED ON TSPN

多媒体同步的一个主要问题是多媒体同步时间要求的描述与建模。文中基于时间流Ｐｅｔｒｉ网模型（ＴＳＰＮ），通过分析ＴＳＰＮ 模型的不足之处，提出了一种新的多媒体同步模型——扩展时间流Ｐｅｔｒｉ网模型（ＸＴＳＰＮ）．ＸＴＳＰＮ 不但可以完全、准确地描述媒体流内和流间的时间行为，而且通过引入容许阻塞时间、回溯算法等对ＴＳＰＮ进行扩展，可以有效地克服网络随机延迟、阻塞和丢包等因素的不良影响，提高了模型的建模能力和对分布式网络环境的适应能力．

Modeling and specifying temporal requirements of the multimedia synchronization is a key issue for distributed multimedia applications. This paper aims to overcome the deficiencies of time stream Petri net (TSPN) in modeling multimedia streams synchronization. Based on TSPN, a new multimedia synchronization model, extended time stream Petri net (XTSPN), is proposed. XTSPN also allows the temporal behavior of both intra\|media and inter\|media to be fully, accurately, and formally described. In particular, XTSPN introduces allowed blocking time, backtracking rules and so on to handle the problem of synchronization failure because of fire interruption caused by random delay, blocking or lost packets. XTSPN is more practical when the condition of distributed network is imperfect.