Attempts to destroy or remove the watermark will seriously impair the quality of the material

and portals for mobile carriers. Despite using a secure network for content file transfer, the control over such content instances ends on arrival at the assigned recipient organizations.

TV Anywhere distribution channels make content available to authorized users through download and/or streaming transactions: VoD service for PC, mobile, and other connected devices such as game consoles. DRM schemes can secure the content delivery until the point of display, but technologically-aware consumers can sometimes remove such protections or capture content with camcorders to then share with, or sell to, the rest of the world.

Equally, premium TV channels distribute content to consumers for viewing as a linear content (live or time-shifted from PVR) or for viewing content as premium movie VoD or push-VoD services. Content is distributed directly to set-top-boxes, integrated digital TV sets or through gateway devices to more devices in the home. The content is securely broadcast and stored on PVR thanks to CA (Conditional Access) or DRM (Digital Rights Management) systems. It is also protected over the HDMI digital interface to the display. But two so-called analog holes are not addressed: the analog outputs of the decoder which can be used to capture the content with a computer, and the home HD display from which high quality pirate copies can be created using consumer camcorders.

Digital video watermarking and fingerprinting principles

Digital watermarking is a process by which specific data is included within multimedia content, creating its own unique identity. As these insertions are slight in terms of payload and are continuously adapted to the content, the watermark is imperceptible and can only be detected and decoded using special watermark detectors. Attempts to destroy or remove the watermark will seriously impair the quality of the material in which it is embedded.

As digital watermarking gives content copies individual identities, it enables the identification, management and tracking of digital multimedia content. It can be used for a variety of different applications and purposes, including broadcast verification, image copyright protection, forensic tracking and mobile commerce.

Figure 2: Simple fingerprinting process

Scenarios using watermarking and fingerprinting Forensic marking uses video watermarking technology to organize the serial numbering of each individual instance of content copies, giving each instance an identity (see figure 3). A forensic tracking database logs watermarked copies and their intended recipient details. This database can be queried for tracking purposes in the event of a suspected piracy event.

Fingerprinting is commonly carried out by extracting several unique features of digital multimedia content that can be stored in the form of a “fingerprint”. The evaluation and identification of content is then performed by comparing the fingerprints with reference fingerprints previously collected in a database (see Figure 2). For digital audiovisual content, both audio and video fingerprints can be extracted, each having significant value in different application areas.

The creation of a fingerprint involves the use of specialized software that decodes the audio or video data and then applies feature extraction algorithms. Digital fingerprints are highly compressed when compared to the original source material and can therefore be easily stored in databases for later comparison. The fingerprints cannot be used to reconstruct the original content.

Figure 1: General digital watermarking process

Figure 3: Forensic marking principles 29

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