Invisible watermarking is a process that modifies multimedia content, shall it be a song, a movie, an e-book or a still image, in a way that cannot be perceived by a user. Such watermarks encode information that can be recovered from copies of that content, even after potential alterations. In particular, watermarking can be exploited to provide a tracing mechanism in case of piracy. If someone makes available copyrighted content in a non-authorized way, she can be identified thanks to the unique watermark that is present in her copy. As such, watermarking acts as a piracy deterrence mechanism: the user knows that she can be traced back if she shares copyrighted content. This technology complements content protection systems such as CAS and DRM whose objective is to prevent the creation of pirate copies.

Harmonizing a Quatuor of Properties.

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Fidelity

Forensic watermarks added to audio-visual content for tracing purposes shall not impair the entertainment experience of the end user. Added watermarks shall therefore remain imperceptible.

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Robustness

Piracy routinely involve a number of alterations to the pirated content either during acquisition (camcording, screencasting, etc) or during storage (re-encoding, aspect-ratio change, etc). Forensic watermarks are expected to survive such operations.

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Throughput

Digital watermarking can be viewed as an auxiliary communications channel that transmits information through the video content itself. It is therefore desirable to embed as much information as possible in a sequence as short as possible in order to identify the pirate with the shortest pirate samples.

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Security

Pirates are likely to design countermeasures to evade forensic watermarks tracing capabilities. Watermarking systems shall therefore manage to withstand targeted attacks designed by pirates knowing technical details of the algorithm.

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Forensic Watermarks for UHD Content

While watermarking has now been around for nearly two decades, it has been so far mainly used in professional applications (previews, screener, dailies protection…). This is currently changing as the use of forensic watermarks to protect the next generation of video content (4k, HDR, HFR, etc) is required. as indicated by the MovieLabs specification released in 2014.

I. The system shall have the ability to securely forensically mark video at the server and/or client to recover information necessary to address breaches.

II. The watermarking shall be robust against corruption of the forensic information.

III. The watermark shall be inserted on the server or on the client such that the valid insertion is guaranteed during playback even if the device and its secrets are compromised.

Two-step Watermarking

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Two-step watermarking refers to watermarking systems that comprise a preprocessing step that identifies how the content could be modified and an embedding step that actually applies modifications to the content to encode the desired identifier. The virtue of such architectures is to offload computationally-intensive operations in the head-end in order to have the lightest embedding module as possible and thereby ease integration, including in legacy consumer electronics devices.

Market Deployment Opportunities

Pirates are likely to design countermeasures to evade forensic watermarks tracing capabilities. Watermarking systems shall therefore manage to withstand targeted attacks designed by pirates knowing technical details of the algorithm.

Movies are distributed prior to theatrical release e.g. for previews of dailies during the creation process, screeners for journalists and members of the academy, etc. At this stage, forensic watermarks are instrumental to safeguard the value of the movie.

After theatrical release, access to recent movies can be granted earlier than to traditional distribution networks pending the presence of forensic watermarks to deter piracy. This is for instance the case of hospitality markets such as entertainment systems in planes, cruises, trains, hotels, etc.

Hollywood studios require the implementation of enhanced protection measures by content distributors to get access to their premium movie library. Video-on-demand services therefore need to implement forensic watermarking to distribute UHD content.

Near instantaneous illegal redistribution is becoming increasingly widespread nowadays and jeopardize existing business models of broadcasters and PayTV operators. In this context, forensic watermarking is instrumental to rapidly identify and shut down sources of illegal re-broadcast.

More Information

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