Enhanced Shot-Based Video Adaptation using MPEG-21 generic Bitstream Syntax Schema

Semantic video adaptation takes into account the relevance of the different fragments of the video content in order to create a tailored video stream based on the user´s preferences. As a shot can be considered as the smallest semantic unit in a video sequence, metadata can be added to each shot using MPEG-7 descriptions. Based on these metadata and the user´s preferences, the original bitstream can be adapted in order to obtain the desired fragments. MPEG-21 DIA offers a tool, gBS schema, for exposing the high-level structure of a binary resource as an XML description. In this paper, shot information is inserted in these descriptions to create a link between metadata and semantic video adaptation. Furthermore, this paper proposes to keep the structure of these descriptions format-agnostic. As a result, only one generic transformation style sheet has to be implemented to support shot-based video adaptation of sequences compliant with different video specifications. Special attention is paid to sequences coded with the H.264/AVC standard as this specification contains several interesting features important for shot-based video adaptation