Description Definition Language
Encyclopedia
DDL is part of the MPEG-7
standard. It gives an important set of tools for the users to create their own Description Schemes (DSs) and Descriptors (Ds). DDL defines the syntax rules to define, combine, extend and modify Description Schemes and Descriptors.
), but a schematic language to represent the audiovisual data results, which must conform to the descriptors, the description schemes and the MPEG-7
descriptions.
MPEG-7 DDL Must:
DDL was comparing and evaluating proposals in the MPEG-7 AHG Test And Evaluation Meeting held in Lancaster. The main agreement was that DDL had to use the XML
syntax, support object-oriented semantics, as well as being able to validate structural, relational and data typing constraints.
Although no proposal satisfied the requirements the DSTC proposal was used as a starting point, extending it with the additions of ideas and components from other proposals and contributors. Moreover, the strategy was to keep tracking and influencing the W3C community, specially the XML Schema, XLink
, XPath
and XPointer
working groups.
At the 51st MPEG meeting, the adoption of the XML Schema syntax with specific MPEG-7 extensions was decided.
MPEG-7
MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 . This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description...
standard. It gives an important set of tools for the users to create their own Description Schemes (DSs) and Descriptors (Ds). DDL defines the syntax rules to define, combine, extend and modify Description Schemes and Descriptors.
Introduction
DDL is not a modeling language, such as the Unified Modeling Language (UMLUnified Modeling Language
Unified Modeling Language is a standardized general-purpose modeling language in the field of object-oriented software engineering. The standard is managed, and was created, by the Object Management Group...
), but a schematic language to represent the audiovisual data results, which must conform to the descriptors, the description schemes and the MPEG-7
MPEG-7
MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 . This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description...
descriptions.
MPEG-7 DDL Must:
- Be able to express relationships of elements within a DS or between two DS, whether they are structural, spatial, temporal, conceptual or hierarchical.
- Give a rich set of unions and references between one or more descriptions and the data they describe.
- Be application and platform independent.
- Be able to specify the descriptors data type, whether they are primary (integers, text, time, ...) or derived (enumerated, ...)
History
In 1999, the team in charge of MPEG-7MPEG-7
MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 . This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description...
DDL was comparing and evaluating proposals in the MPEG-7 AHG Test And Evaluation Meeting held in Lancaster. The main agreement was that DDL had to use the XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
syntax, support object-oriented semantics, as well as being able to validate structural, relational and data typing constraints.
Although no proposal satisfied the requirements the DSTC proposal was used as a starting point, extending it with the additions of ideas and components from other proposals and contributors. Moreover, the strategy was to keep tracking and influencing the W3C community, specially the XML Schema, XLink
XLink
XML Linking Language, or XLink, is an XML markup language and W3C specification that provides methods for creating internal and external links within XML documents, and associating metadata with those links.-The XLink specification:...
, XPath
XPath
XPath is a language for selecting nodes from an XML document. In addition, XPath may be used to compute values from the content of an XML document...
and XPointer
XPointer
XPointer is a system for addressing components of XML based internet media.XPointer is divided among four specifications: a "framework" which forms the basis for identifying XML fragments, a positional element addressing scheme, a scheme for namespaces, and a scheme for XPath-based addressing...
working groups.
At the 51st MPEG meeting, the adoption of the XML Schema syntax with specific MPEG-7 extensions was decided.
Requirements
As defined in the MPEG-7 requirements document:- Compositional capabilities: DDL shall allow new DSs and Ds to be created and existing DSs to be modified or extended.
- Unique Identification: A unique identifier should be allowed for each D or DS.
- Primitive Data Types: A set of primitive data type, such as integer, real, date, ..., shall be provided.
- Composite Data Types: Composite data types, as color histogramColor histogramIn image processing and photography, a color histogram is a representation of the distribution of colors in an image. For digital images, a color histogram represents the number of pixels that have colors in each of a fixed list of color ranges, that span the image's color space, the set of all...
s, RGB values, enumerated types, ..., shall be allowed to be described. - Multiple Media Types: DDL shall provide a mechanism to relate Ds to data of multiple media types, not necessarily of the same nature.
- Various types of DS instantiations: Full, partial, full-mandatory and partial-mandatory instantiations should be allowed.
- Relationships within a DS and between DSs: DDL shall be able to express spatial, temporal, structural and conceptual relationships between the elements of a DS or between different DSs.
- Relationships between description and data: A rich model for links and references between on or more descriptions and the described data shall be supplied.
- Link to oncologies: A link mechanism between a description and several oncologies shall be supplied too.
- Platform independent: DDL shall be platform and application independent.
- Grammar: DDL's grammar shall be unambiguous and easily parsed.
- Validation of constraints: DDL's parser shall be able to validate: values of properties, structures, related classes and values of properties of related classes.
- Intellectual property management: A mechanism for the expression of Intellectual Property Management and Protection (IPMP), that is what Digital Rights ManagementDigital rights managementDigital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...
(DRM) is known as in the MPEG world, for DSs and Ds. - Human readability: DDL shall allow DSs and Ds to be read by humans.
MPEG-7 Specific Extensions To XML Schema
They are basic to satisfy the MPEG-7 DDL requirements- Distribution and datatype matrix
- Written references
- Enumerated datatypes, such as MimeMimeThe word mime is used to refer to a mime artist who uses a theatrical medium or performance art involving the acting out of a story through body motions without use of speech.Mime may also refer to:* Mime, an alternative word for lip sync...
Type, CountryCode, RegionCode, Character-SetCode, ...