Efficient Delivery within the MPEG-21 Framework

MPEG-21, the new Multimedia Framework standard is nearing completion. It is centred around the concept of a Digital Item which is exchanged in the form of an XML declaration. This paper initially considers the challenge of compressing these Digital Item Declarations and presents conclusive results showing that schema based compression is the best solution. A new technique is then presented whereby the one-way delivery framework is expanded to allow client selection and control of Digital Item fragment transmission. This uses a new Remote XML Exchange Protocol (RXEP) which significantly reduces storage and time delays in mobile environments. Finally, the new approach is combined with schema-based compression to offer maximum efficiency.