User-centered control within multimedia presentations

The focus of much of the research on providing user-centered control of multimedia has been on the definition of models and (meta-data) descriptions that assist in locating or recommending media objects. While this can provide a more efficient means of selecting content, it provides little extra control for users once that content is rendered. In this article, we consider various means for supporting user-centered control of media within a collection of objects that are structured into a multimedia presentation. We begin with an examination of the constraints of user-centered control based on the characteristics of multimedia applications and the media processing pipeline. We then define four classes of control that can enable a more user-centric manipulation within media content. Each of these control classes is illustrated in terms of a common news viewing system. We continue with reflections on the impact of these control classes on the development of multimedia languages, rendering infrastructures and authoring systems. We conclude with a discussion of our plans for infrastructure support for user-centered multimedia control.