Presently, there are three main ESG systems used in DVB-H (DVB, 2004) systems : 1. CBMS (DVB, 2006), promoted by the digital video broadcasting project (DVB). 2. OAI (NOKIA, 2006), promoted by NOKIA. 3. OMA (OMA, 2006), still in draft version, promoted by the open mobile alliance. All of them have a lot of similarities and are based on same concepts and technologies. Some of these similarities are: • The use of XML (W3C, 1998) to describe fragments. • The use of FLUTE (Paila, Luby, Lehtonen, Roca, & Walsh, 2004) as transport protocol. • A similar data model. • All of them can split the broadcast contents in several sessions.
Presently, there are three main ESG systems used in DVB-H (DVB, 2004) systems:
CBMS (DVB, 2006), promoted by the digital video broadcasting project (DVB).
OAI (NOKIA, 2006), promoted by NOKIA.
OMA (OMA, 2006), still in draft version, promoted by the open mobile alliance.
All of them have a lot of similarities and are based on same concepts and technologies. Some of these similarities are:
The use of XML (W3C, 1998) to describe fragments.
The use of FLUTE (Paila, Luby, Lehtonen, Roca, & Walsh, 2004) as transport protocol.
A similar data model.
All of them can split the broadcast contents in several sessions.
All actual ESG systems work at IP level, hiding other layers such as MPEG2-TS (ISO/IEC, 1994), PIDs. Also, all of them use FLUTE/ALC as transport protocol and allow the splitting of the broadcast in several sessions (each session is broadcasted over a different IP/port and has its own bitrate).
Another similarity at protocol level is the way of referencing media. When media is referenced, it is done by means of a session description protocol (SDP) file (Handley & Jacobson, 1998).
All ESGs systems has a global entry point called bootstrap. The bootstrap is broadcasted in a well-known IP address and port. The bootstrap carries with information about the providers present on the network and where their ESGs are being broadcasted. When a terminal switches on, it must receive the bootstrap and look inside for a valid provider checking the providers list. After that, the terminal reads the multicast address where the ESG is being broadcasted and start retrieving the service guide information.
Data models have also a lot of similarities, covering three main domain concepts: provisioning, core, and access. Each concept is represented using different fragment types:
Core: Service, schedule, content
Access: Access and session description
Provisioning: Purchase item, data, and channel
Fragment semantics are1:
As the part of the service guide, the service fragment forms a central hub referenced by access, schedule, content, and purchase Item fragments.
Key Terms in this Chapter
Conceptual Clustering: A type of learning by observations and a way of summarizing data in an understandable manner.
MPEG-7 MDS: MPEG-7 Multimedia Description Schemes (ISO/IEC 15938-5) specify the different description tools that are not visual and audio ones, that is, generic and multimedia ones.
Domain Ontology: They capture valid for a particular type of domain: for example, electronic, medical, mechanic, and digital domain.
Video Data Mining: A process of finding correlations and patterns previously unknown from large video databases.
Core Ontology: Ontology that is valid across several domains.
Video Ontology: In a video ontology, concept, properties, and relationships can be represented by multimedia entities, that is, audio, images, and video, or terms.
MPEG-7: It is a standard for describing the multimedia content data that supports some degree of interpretation of the information meaning, which can be passed onto, or accessed by, a device or a computer code.
Semantic Web: It is a Web data providing a common framework that allows data to be shared and reused across application, enterprise, and community boundaries.
Ontology: Ontology provides a formal, explicit specification of a shared conceptualization of a domain that can be communicated between people and heterogeneous and widely spread application systems.