Hierarchical traceability of multimedia documents

Illegal copying of multimedia files has become a very common practice. Indeed, with the rapid development of means of communication, sharing, copying and illegal downloading have become a very easy handling action, at everybody´s reach. The magnitude of this continuously increasing phenomenon may have a significant economic impact since it induces a marked loss on turnover. To cope with this huge problem, it becomes necessary to control video traffic and ensure traceability. Thus, each user receives a personalized media release, containing a personal identifier inserted through a robust watermarking technique. If this copy is redistributed illegally, we are able to trace the dishonest user who can be prosecuted. This expresses an urgent need for implementing a reliable fingerprinting scheme with high performances. In this context, we present in this paper a hierarchical fingerprinting system based on Tardos code in order to reduce computational costs required for the pirates´ detection. Both theoretical analyses and experimental results are provided to show the performance of the proposed system.