An architecture for recording and playback of MPEG4-based collaborative virtual environments.

Abstract

A collaborative virtual environment provides the means for different parties to interact with one another and the virtual environment in which they preside and share its space, despite each participant being at a geographically distant location. The development of such an application delves into many areas of research and requires the integration of various technologies some of which are content compression, efficient updating, timely, reliable and efficient transport of content, event synchronization and many more. MPEG4 is an international standard that deals with some of these issues by putting forward a binary specification of scenes, the updates needed to change the scene, multiplexing natural and synthetic content, synchronization of events and other features that may be used in developing collaborative virtual environments. This thesis is extending a collaborative framework based on MPEG4 to allow for recording and playback of entire sessions carried out in a collaborative virtual environment and also presents the implementation of an application utilizing such a framework. The work involves the development of a framework supporting MPEG4's Synchronization Layer (SL) to capture events and their temporal characteristics, storing the information according to the standard specification of MPEG4, as well as providing the capability to of playing back the events as they had originally unfolded. The collaborative framework that will be extended is COSMOS (Collaborative System framework based on MPEG4 Objects and Streams) which provides a basic framework for the development of collaborative virtual environments. Before extending this framework for recording and playback capabilities, there is a need to complement it with additional interaction capabilities so as to have a meaningful recording session. Such additions include new human-computer interfaces, the ability to manipulate arbitrary objects, adding new objects to the scene, and loading and triggering and sharing predefined animation.