面向同步实时授课的多媒体通信模型

Multimedia Communication Model for Synchronous Real-time Teleteaching

针对基于IP网的同步实时授课系统在多媒体通信方面存在的问题，提出了一种适用于描述实时授课中多媒体通信的四元组结构模式，基于此模式，建立了同步实时授课系统的多媒体通信模型，论述了模型中的主要问题，如组播数据跨网段传输机制和镜头焦点交互机制，并对模型进行了性能评估。该模型已在基于IP网的多媒体远程教育系统RealClass中得到应用和验证，并具有良好的可扩展性。

Aiming at the existing issues on multimedia communication in synchronous real-time teleteaching system over IP network, a 4-tuple structural mode of multimedia communication is introduced , and a communication model is built according to the mode. Moreover, some key issues of this model, such as the cross-subnet multicast mechanism and the focus interaction mechanism, are discussed. Finally, the performance of this model is evaluated. The communication model has been applied successfully in the authaors' interactive synchronous real-time teleteaching system named RealClass, which has good extendibility.