對內(nèi)容的特徵作定義

1、1MPEG-7 Overview - part 22ReviewnDescriptor (D) - 對內(nèi)容的特徵作定義。 - 通常用以描述low-level features 。nDescription Scheme (DS) - 通常用以描述 high-level features 。 - DS和D的區(qū)別是：D僅包含基本的資料類型，而DS可 同時(shí)包含D與 DS。3Review (contd.)nD、DS與DDL之關(guān)係圖如下 :DDDDSDSDDDDSDDL4DDL (Description Definition Language)nThe DDL defines the syntactic

2、rules to express and combine DSs and Ds.nThe DDL is not a modeling language but a schema language to represent the results of modeling audiovisual data, i.e. DSs and Ds.nIn March 2000, MPEG was decided to adopt XML Schema Language as the MPEG-7 DDL.5DDL (contd.)nHowever, XML Schema language has not

3、been designed specifically for AV content, certain extensions have been necessary. Array and matrix datatypes Built-in primitive time datatypes6BiMnXML has not been designed to deal ideally in a real-time, constrained and streamed environment.nTo overcome it, MPEG-7 Systems defines a generic framewo

4、rk to facilitate the carriage and processing of MPEG-7 descriptions: BiM (Binary Format for MPEG-7). 7BiM (contd.)nThe features of BiM are : BiM binary format is not dedicated to any specific XML language. BiM is a schema oriented encoding scheme. BiM is a pre-parsed format BiM allows a parameterize

5、d transmission of XML document, like depicted below : Fig. Different streaming strategies of the same XML file8MPEG-7 TerminalnThe entity that makes use of the coded representations of the multimedia content description is referred to as the “terminal”.nThe terminal has three main architectural laye

6、rs : application layer system layer delivery layer9MPEG-7 Terminal (contd.)nAn MPEG-7 terminal consumes description streams and outputs a representation of the description called the current description tree.nDescription streams consist of Access Units (AUs). textual description stream binary descri

7、ption stream10MPEG-7 Terminal (contd.)nAn AU is composed of any number of Fragment Update (FU) Units, each of which is extracted in sequence by the fragment update component extractor.nEach FU unit consists of : a FU command a FU context a FU payload11MPEG-7 Terminal (contd.)12Reference Software: th

8、e eXperimentation ModelnThe XM software is the frame work for the for all the reference code of the MPEG-7 standard. nThe XM software has only a command line interface, which does not allow any interaction during run-time.nThe modules of the XM software are designed in a way, that all modules are us

9、ing specified interfaces.13Reference Software: the eXperimentation Model (contd.)nWithin the XM software framework, applications are related to one particular descriptor or description scheme. Server (or extraction) applications Client applications14Application types in the XM softwarenExtraction fr

10、om Media 15Application types in the XM software(contd.)nSearch & Retrieval Application16Application types in the XM software(contd.)nMedia Transcoding Application17Application types in the XM software(contd.)nDescription Filtering Application18The MPEG-7 key application modelnApplications, which

11、 are implemented in the XM software are also called key applications.nThe inputs and outputs of key applications are:19Key applications vs. real world applicationsnIn general, combining the key applications will form complex applications.20MPEG-7 Conformance TestingnMPEG-7 Conformance Testing includ

12、es the guidelines and procedures for testing conformance of MPEG-7 implementations.nThere are two kinds of conformance testing : conformance testing for descriptions conformance testing for terminals21MPEG-7 Conformance Testing(contd.)nThe objective of the conformance testing of descriptions is to check the syntactic compliance with ISO/IEC IEC 15938 parts 1 5. 22MPEG-7 Conforma