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.