<title>Media synchronization control considering features of MPEG video</title>

The intra-media synchronization control scheme for MPEG video over Internet, where communication quality is not always guaranteed, are proposed in this paper. In order to obtain expected quality of MPEG video, four basic control functions and one subfunction for a minimum size of controlled image (hereinafter referred to as MU: Media Unit) are introduced. The proposed basic control functions are classified into two types. One type lays emphasis on realizing real-time display. Another type lays emphasis on keeping quality of images. The former type includes short (to reduce periods to display MUs), change (to realize more moderate control than short function) and skip (to abandon a received MU) functions. The latter type includes smooth (to make the variations of periods to display MUs small by postponing a display time) function. And a sort function, which is to display MUs in regular order, is also prepared in the proposed control scheme. Combinations of these control functions are pursued at a client side alone. Characteristics of proposed control functions are described with simulation results. Especially, in order to execute the subjective assessment only depending on psychological assessment factors, a SD (Semantic Differential) method, which is a kind of psychological factor analysis, is introduced. As the result, it is confirmed that a smooth function is the most effective to keep quality of images, and in order to realize realtime display, the short, change or skip function should be combined.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.