A framework for fully format-independent adaptation of scalable bit streams

This paper presents a framework for modeling and adaptation of arbitrary scalable multimedia bit streams in a manner that is fully format agnostic ("universal transcoding"). It is entitled structured scalable metaformats (SSM), and is based on establishing a universal model for all scalable bit streams, which in turn allows a compact specification of the set of allowed adaptations, and also how the bit stream adaptation is performed. In order to enable format-agnostic adaptation, two elements are standardized: 1) metadata associated with a scalable bit stream conveying the parameters of its SSM model, and how it is to be manipulated to obtain various adapted versions, as well as information that allows making appropriate adaptation decisions using only the model parameters and 2) a specification of outbound network and terminal constraints, for real-time decisions based on both user preferences and network conditions. By interpreting the descriptions, a universal adaptation engine can adapt the content to suit the specified needs and preferences of recipients, without knowledge of the specifics of the content, its encoding and encryption. With universal adaptation, different adaptation infrastructures are no longer needed for different types of scalable media, eliminating the high costs of traditional transcoding. Many of the SSM concepts have been adopted into the MPEG-21 Part 7 standard entitled Digital Item Adaptation.