Spread spectrum-based video watermarking algorithms for copyright protection

Merged with duplicate record 10026.1/2263 on 14.03.2017 by CS (TIS)Digital technologies know an unprecedented expansion in the last years. The consumer can now benefit from hardware and software which was considered state-of-the-art several years ago. The advantages offered by the digital technologies are major but the same digital technology opens the door for unlimited piracy. Copying an analogue VCR tape was certainly possible and relatively easy, in spite of various forms of protection, but due to the analogue environment, the subsequent copies had an inherent loss in quality. This was a natural way of limiting the multiple copying of a video material. With digital technology, this barrier disappears, being possible to make as many copies as desired, without any loss in quality whatsoever. Digital watermarking is one of the best available tools for fighting this threat. The aim of the present work was to develop a digital watermarking system compliant with the recommendations drawn by the EBU, for video broadcast monitoring. Since the watermark can be inserted in either spatial domain or transform domain, this aspect was investigated and led to the conclusion that wavelet transform is one of the best solutions available. Since watermarking is not an easy task, especially considering the robustness under various attacks several techniques were employed in order to increase the capacity/robustness of the system: spread-spectrum and modulation techniques to cast the watermark, powerful error correction to protect the mark, human visual models to insert a robust mark and to ensure its invisibility. The combination of these methods led to a major improvement, but yet the system wasn't robust to several important geometrical attacks. In order to achieve this last milestone, the system uses two distinct watermarks: a spatial domain reference watermark and the main watermark embedded in the wavelet domain. By using this reference watermark and techniques specific to image registration, the system is able to determine the parameters of the attack and revert it. Once the attack was reverted, the main watermark is recovered. The final result is a high capacity, blind DWr-based video watermarking system, robust to a wide range of attacks.BBC Research & Developmen

Contributions to folded reed-solomon codes for burst error correction

Ph.DDOCTOR OF PHILOSOPH

Near-optimal Balanced Reliable Broadcast and Asynchronous Verifiable Information Dispersal

In this paper, we present near-optimal asynchronous Byzantine reliable broadcast (RBC) protocols with balanced costs and an improved asynchronous verifiable information dispersal (AVID) protocol. Assuming the existence of collision-resistant hash functions, our RBC protocol broadcasts a message $M$ among $n$ nodes with total communication cost $O(n|M|+\kappa n^2)$ and per-node communication cost $O(|M|+\kappa n)$. In contrast, the state-of-the-art reliable broadcast protocol either has per-node cost $O(|M|+\kappa \log n)$, or has imbalanced costs where the broadcaster incurs $O(n|M|)$ while other nodes incur a communication cost of $O(|M|+\kappa n)$. We also present an error-free RBC protocol that makes no computational assumption and has total communication cost $O(n|M|+ n^2\log n)$ and per-node communication cost $O(|M|+ n\log n)$. In contrast, the state-of-the-art error-free RBC protocol has total cost of $O(n|M|+ n^3\log n)$, and the broadcaster has imbalanced cost of $O(n|M|+ n^2\log n)$. We then use our new balanced RBC and additional techniques to design an asynchronous verifiable information dispersal (AVID) protocol with total dispersal cost $O(|M|+\kappa n^2)$, retrieval cost $O(|M|+\kappa n)$, and no trusted setup. In our AVID protocol, the client incurs a communication cost of $O(|M|+\kappa n)$ in comparison to $O(|M|+\kappa n\log n)$ of prior best. Moreover, each node in our AVID protocol incurs a storage cost of $O(|M|/n+\kappa)$ bits, in comparison to $O(|M|/n+\kappa \log n)$ bits of prior best. Finally, we present lower bound results on communication cost and show that our balanced RBC and AVID protocols have near-optimal communication costs -- only an factor of $O(\kappa)$ or $O(\log n)$ gap from the lower bounds

Committing AVID with Partial Retrieval and Optimal Storage

Asynchronous Verifiable Information Dispersal (AVID) allows a dealer to disperse a message $M$ across a collection of server replicas consistently and efficiently, such that any future client can reliably retrieve the message $M$ if some servers fail. Since AVID was introduced by Cachin and Tessaro in 2005, several works improved the asymptotic communication complexity of AVID protocols. However, recent gains in communication complexity have come at the expense of sub-optimal storage, which is the dominant cost in long-term archiving. Moreover, recent works do not provide a mechanism to detect errors until the retrieval stage, which may result in completely wasted long-term storage if the dealer is malicious. In this work, we contribute a new AVID construction that achieves optimal storage and guaranteed output delivery, without sacrificing on communication complexity during dispersal or retrieval. First, we introduce a technique that bootstraps from dispersal of a message with sub-optimal storage to one with optimal storage. Second, we define and construct an AVID protocol that is robust, meaning that all server replicas are guaranteed at dispersal time that their fragments will contribute toward retrieval of a valid message. Third, we add the new possibility that some server replicas may lose their fragment in between dispersal and retrieval (as is likely in the long-term archiving scenario). This allows us to rely on fewer available replicas for retrieval than are required for dispersal

Robust P2P Live Streaming

Projecte fet en col.laboració amb la Fundació i2CATThe provisioning of robust real-time communication services (voice, video, etc.) or media contents through the Internet in a distributed manner is an important challenge, which will strongly influence in current and future Internet evolution. Aware of this, we are developing a project named Trilogy leaded by the i2CAT Foundation, which has as main pillar the study, development and evaluation of Peer-to-Peer (P2P) Live streaming architectures for the distribution of high-quality media contents. In this context, this work concretely covers media coding aspects and proposes the use of Multiple Description Coding (MDC) as a flexible solution for providing robust and scalable live streaming over P2P networks. This work describes current state of the art in media coding techniques and P2P streaming architectures, presents the implemented prototype as well as its simulation and validation results