Video Adaptation: Concepts, Technologies, and Open Issues
Video adaptation is an emerging field that offers a rich body of techniques for answering challenging questions in pervasive media applications. It transforms the input video(s) to an output in video or augmented multimedia form by utilizing manipulations at multiple levels (signal, structural, or semantic) in order to meet diverse resource constraints and user preferences while optimizing the overall utility of the video. There has been a vast amount of activity in research and standard development in this area. This paper first presents a general framework that defines the fundamental entities, important concepts (i.e., adaptation, resource, and utility), and formulation of video adaptation as constrained optimization problems. A taxonomy is used to classify different types of adaptation techniques. The state of the art in several active research areas is reviewed with open challenging issues identified. Finally, support of video adaptation from related international standards is discussed.