Synchronization Schemes for Controlling VCR-Like User Interactions in Interactive Multimedia-on-Demand (MOD) Systems

The provision of many VCR-like user interactions, e.g. reverse, skip, freeze-restart and scale, makes multimedia applications more flexible and useful to users. However, due to the unpredictable and uncontrollable network delay and jitter, the provision of VCR-like functions complicates the processing of multimedia synchronization a lot. The main reason is that (i) those media units stored in the client buffers and transmitting in the networks may be either useful or useless and (ii) the servers' media transmission should be adjusted when the corresponding presentation is resumed. Additionally, different VCR-like user interactions have their own processing considerations, which require different control schemes. In this paper, we propose some control schemes that are based on the feedback-adaptive mechanism. Based on the control schemes, we developed a Multimedia-on-Demand system in which text, image, graphics, audio and video media are transmitted from the server site to the client site through text, image, graphics, audio and video communication channels respectively. Some performance measurements of the proposed control schemes are also given in this paper.