1 MPEG-7 Overview - part 2

2 Review Descriptor (D) - 對內容的特徵作定義。 - 通常用以描述 low-level features 。 Description Scheme (DS) - 通常用以描述 high-level features 。 - DS 和 D 的區別是： D 僅包含基本的資料類型，而 DS 可 同時包含 D 與 DS 。

3 Review (contd.) D 、 DS 與 DDL 之關係圖如下 : DDD DS DDD DDL

4 DDL (Description Definition Language) The DDL defines the syntactic rules to express and combine DSs and Ds. The DDL is not a modeling language but a schema language to represent the results of modeling audiovisual data, i.e. DSs and Ds. In March 2000, MPEG was decided to adopt XML Schema Language as the MPEG-7 DDL.

5 DDL (contd.) However, XML Schema language has not been designed specifically for AV content, certain extensions have been necessary. ․ Array and matrix datatypes ․ Built-in primitive time datatypes

6 BiM XML has not been designed to deal ideally in a real-time, constrained and streamed environment. To overcome it, MPEG-7 Systems defines a generic framework to facilitate the carriage and processing of MPEG-7 descriptions: BiM (Binary Format for MPEG-7).

7 BiM (contd.) The 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 parameterized transmission of XML document, like depicted below : Fig. Different streaming strategies of the same XML file

8 MPEG-7 Terminal The entity that makes use of the coded representations of the multimedia content description is referred to as the “ terminal ”. The terminal has three main architectural layers : ․ application layer ․ system layer ․ delivery layer

9 MPEG-7 Terminal (contd.) An MPEG-7 terminal consumes description streams and outputs a representation of the description called the current description tree. Description streams consist of Access Units (AUs). ․ textual description stream ․ binary description stream

10 MPEG-7 Terminal (contd.) An AU is composed of any number of Fragment Update (FU) Units, each of which is extracted in sequence by the fragment update component extractor. Each FU unit consists of : ․ a FU command ․ a FU context ․ a FU payload

11 MPEG-7 Terminal (contd.)

12 Reference Software: the eXperimentation Model The XM software is the frame work for the for all the reference code of the MPEG-7 standard. The XM software has only a command line interface, which does not allow any interaction during run-time. The modules of the XM software are designed in a way, that all modules are using specified interfaces.

13 Reference Software: the eXperimentation Model (contd.) Within the XM software framework, applications are related to one particular descriptor or description scheme. ․ Server (or extraction) applications ․ Client applications

14 Application types in the XM software Extraction from Media

15 Application types in the XM software (contd.) Search & Retrieval Application

16 Application types in the XM software (contd.) Media Transcoding Application

17 Application types in the XM software (contd.) Description Filtering Application

18 The MPEG-7 key application model Applications, which are implemented in the XM software are also called key applications. The inputs and outputs of key applications are:

19 Key applications vs. real world applications In general, combining the key applications will form complex applications.

20 MPEG-7 Conformance Testing MPEG-7 Conformance Testing includes the guidelines and procedures for testing conformance of MPEG-7 implementations. There are two kinds of conformance testing : ․ conformance testing for descriptions ․ conformance testing for terminals

21 MPEG-7 Conformance Testing (contd.) The objective of the conformance testing of descriptions is to check the syntactic compliance with ISO/IEC IEC parts 1 – 5.

22 MPEG-7 Conformance Testing (contd.) The conformance testing for terminal involves the comparison of the result of processing a description using a reference terminal against the result using the test terminal.