Víctor Rodríguez Doncel
This Thesis presents a computer representation language for agreements on multimedia content and the mechanisms to execute them in the framework of a content distribution system, Content distribution systems trade audiovisual material in exchange of economic compensation in a framework of secure transactions between identified users, what is generally known as Digital Rights Management (DRM) systems. One of the most notable frameworks for the creation, protection, distribution and rendering of multimedia content has been that of MPEG (Moving Pictures Experts Group), whose specification is open, has partial code availability and it has been sanctioned as a collection of International Standards promulgated by the International Organization for Standardization (ISO). But neither the MPEG framework nor the other existing DRM systems handle consistently the complete intellectual property value chain, tending to focus almost exclusively on distributor to consumer transactions. These transactions are governed by digital licenses expressed with Rights Expression Languages (REL). A media value chain as the process by which a work is conceived, represented, performed, fixated, distributed, or broadcast, and lastly consumed; acknowledging that different chains exist for different works, going through different transformations, being distributed through different channels and being consumed in different manners. These value chain, largely ignored by current REL languages, may have a computerized representation, with a very precise description. Particularly, the transactions relevant regarding the intellectual property, can be precisely captured due to the international consensus and international agreements of universal validity. The intellectual property value chain is described with the Media Value Chain Ontology proposed in the Thesis, a representation in OWL (Ontology Web Language) of the workflow of multimedia content and the successive transfers of intellectual property. The Media Value Chain Ontology describes the different types of intellectual property objects (original works, manifestations, instances etc.), the different acknowledged roles intervening in the process (creator, distributor etc.), and the different actions relevant to the intellectual property. It also covers the precise relations between these entities, and it provides as well the mechanisms to represent authorisations, prohibitions and obligations. The formalization of the model under the terms of Description Logics allows performing reasoning operations and the implementation of advanced authorisation mechanisms of the licenses expressed with the ontology. This Thesis also proposes the conversion of narrative contracts in the audiovisual market to the format of digital licenses, by means of a rich knowledge representation schema, where the obligations and permissions exchanged in a contract are dealt as expressions of the deontic logic, and they can determine the behaviour of the distribution platform. A semantic authoriser is proposed which is able to execute rules, evaluate the conditions and the context and give the proper response. The representation of the value chain proposed here, as well as the conversion from contracts to licenses has been a part of different projects and has worked tightly integrated with other elements of wider Digital Rights Management systems. In practice, and in order to easily access to the ontology features, an API in Java is also proposed. On top of it, several applications have been developed demonstrating the MVCO reasoning capabilites to resolve queries on the intellectual property value chain: which legal nature has a given resource, who is the rights owner of the resource, from which intellectual property object a resource derives, which actions are allowed on it, etc. Parts of this work have been integrated in the MPEG-21 framework.