Over view(编码) standardized ways to support ■ Coding(编码) representing units of audio, visual, audiovisual content Composition(合成) I describing how these objects are composed together to produce compound media objects Multiplex(多路复用和合成) a multiplex and synchronize data associated with media objects ■ Interaction(交互性) a interacting with userOverView（编码） ◼ standardized ways to support: ◼ Coding（编码） ◼ representing units of audio, visual, audiovisual content ◼ Composition（合成） ◼ describing how these objects are composed together to produce compound media objects ◼ Multiplex（多路复用和合成） ◼ multiplex and synchronize data associated with media objects ◼ Interaction（交互性） ◼ interacting with user