Thanks to technological evolutions, the number of devices capable of playing video bitstreams is growing. The heterogeneity in these devices grows in terms of screen resolution, processing power, and available band width. In this paper, we describe an MPEG-21 Bitstream Syntax Description Language- based (BSDL-based) adaptation framework that allows providers to easily adapt scalable bitstreams without having to recode the original bitstream. We describe the steps necessary to adapt the bitstreams through BSDL. The main contribution of this paper is an optimized adaptation framework using a Bitstream Syntax Schema developed to minimize the size of the Bitstream Syntax Descriptions (BSDs). Furthermore, we created a Streaming Transformations for XML Stylesheet (STX-stylesheet) to exploit the advantages of Fine Grain Scalability, this to adapt the bitrate of Scalable Video Coding bitstreams in the most accurate way possible. Our results show that BSDL-based adaptation is able to compete with binary adaptation tools. The target bitrates can be reached within a margin of 2%, which is comparable to the reference software which uses binary adaptation.
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