In order to efficiently deal with the heterogeneity in the current and future multimedia ecosystem, it is necessary that content can be adapted in a format-agnostic manner. A first step toward a solution, able to fulfill the just mentioned requirement, is to rely on a scalable video codec and to describe the high-level structure of the resulting bitstreams in such a way that every terminal can understand it, in particular by using XML. This paper describes how such descriptions can be generated by making use of the media format independent BintoBSD tool of the MPEG-21 BSDL standard. However, regarding the current status of BSDL, it is impossible to create a description in real time and to keep the generation speed constant over the complete sequence. In this paper, we describe a number of extensions and algorithmic modifications that make it possible to generate a description of a bitstream in real time and at a constant speed. Our approach results in a significant reduction of the original execution times (up to 99% for the H.264/AVC coding format) and in a constant memory usage.