Sylvain Devillers

Bitstream syntax description: a tool for multimedia resource adaptation within MPEG-21

Abstract In this paper, a generic method is described to allow the adaptation of different multimedia resources by a single, media resource-agnostic processor. This method is based on an XML description of the media resources bitstream syntax, which can be transformed to reflect the desired adaptation and then be used to generate an adapted version of the bitstream. Based on this concept, two complementary technologies, BSDL 2 and gBS Schema, are presented. The two technologies provide solutions for parsing a bitstream to generate its XML description, for the generic structuring and marking of this description, and the generation of an adapted bitstream using its transformed description. The two technologies can be used as stand-alone tools; however, a joint approach has been developed in order to harmonise the two solutions and exploit their strengths. This paper is focusing on the gBS Schema and the joint BSDL/gBS Schema harmonised approach.

Bitstream syntax description-based adaptation in streaming and constrained environments

The seamless access to rich multimedia content on any device and over any network, usually known as Universal Multimedia Access, requires interoperable description tools and adaptation techniques to be developed. To address the latter issue, MPEG-21 Digital Item Adaptation (DIA) introduces the Bitstream Syntax Description (BSD) framework, which provides tools for adapting multimedia content in a generic (i.e., coding format independent) way. The basic idea is to use the eXtensible Markup Language (XML) to describe the high-level structure of a binary media bitstream, to transform its description [e.g., by means of eXtensible Stylesheet Language Transformations (XSLT)], and to construct the adapted media bitstream from the transformed description. This paper presents how this basic BSD framework, initially developed for nonstreamed content and suffering from inherent limitations and high memory consumption of XML-related technologies such as XSLT, can be advanced and efficiently implemented in a streaming environment and on resource-constrained devices. Two different attempts to solve the inherent problems are described. The first approach proposes an architecture based on the streamed processing of Simple Application Programming Interface for XML (SAX) events and adopts Streaming Transformations for XML (STX) as an alternative to XSLT, whereas the second approach breaks a BSD up into well-formed fragments called process units that can be processed individually by a standard XSLT processor. The current status of our work, as well as directions for future research, are given.

Design and Evaluation of a Metadata-Driven Adaptation Node

MPEG-21 digital item adaptation (DIA) allows for a media codec agnostic multimedia adaptation approach which enables the implementation of generic adaptation engines. However, DIA is optimized for static, server-based adaptation. In this paper we introduce novel mechanisms to extend the DIA approach towards dynamic and distributed scenarios. This facilitates the placement of generic adaptation nodes which perform media codec agnostic and dynamic adaptation anywhere along the content delivery path. To validate our work we implemented such an adaptation node and evaluate its performance.

Bitstream Syntax Description Language for 3D MPEG-4 view-dependent texture streaming

In modern multimedia applications, scalability is a key functionality that allows transmission and representation of content in a wide variety of networks and terminals. In order to obtain full advantage of scalability features, techniques for detailed description and transformation of multimedia contents are needed. In this paper, the Bitstream Syntax Description Language is used for describing the structure of an MPEG-4 wavelet-coded texture. An XML-based bitstream description transformation is then applied for selecting some texture regions at an appropriate quality, effectively scaling down the processing and bandwidth requirements for view-dependent texture transmission. Appropriately applying this technique to 3D streaming guarantees quality-of-service, i.e. it certifies the best quality at limited network/processing resources.