Interaction information can be processed locally, or transmitted to the sender. I am familiar with other MPEG Systems specifications. The fundamental difference is that MPEG-4 addresses the coded representation of audiovisual objects , both natural and synthetic . In addition, the object-based architecture necessitates changes in the way audiovisual information is multiplexed. Much of the functionality that MPEG-4 provides comes from the Systems layer.
Systems supports four basic functions that are explained in detail below.
Individual objects may be natural or synthetic, aural or visual, 2D or 3D, and are coded using tools defined by the Audio, Video and SNHC Groups. This information is constructed in a hierarchical manner which can be represented as a tree. The leaf nodes of such tree are always AV objects. The other nodes perform grouping, transformations, etc. The hierarchical structure simplifies scene construction as well as content editing using MPEG-4 bitstreams directly.