In the late 1990’s the industry had been captured by the vision of “500 hundred channels” and telcos thought they could offer interactive media services. With the then being deployed MPEG-1 and MPEG-2, and, with MPEG-4 under development, MPEG expected that users would have zillions of media items.
MPEG-7 started with the idea of providing a standard that would enable users to find the media content of their interest in a sea of media content. Definitely, MPEG-7 deviates from the logic of the previous two standards and the technologies used reflect that because it provides formats for data (called metadata) extracted from multimedia content to facilitate searching in multimedia items. As shown in the figure, metadata can be classified as Descriptions (metadata extracted from the media items, especially audio and video) and Description Schemes (compositions of descriptions). REF _Ref7642121 \h Figure 54 also shows two additional key MPEG-7 technologies. The first is the Description Definition Language (DDL) used to define new Descriptors and the second id XML Compression. With Descriptions and Description Schemes represented in verbose XML, it is clear that MPEG needed a technology to effectively compress XML.
Figure 54 – Components of the MPEG-7 standard
An overview of the entire MPEG-7 standard is available here. The official title of MPEG-7 is Multimedia content description interface and the standard is composed of 16 parts, some of which are:
- Part 1 – Systems has similar functions as the parts 1 of previous standards. In addition, it specifies a compression method for XML schemas used to represent MPEG-7 Descriptions and Description Schemes.
- Part 2 – Description definition language breaks the Systems-Video-Audio traditional sequences of previous standards to provide a language to describe descriptions (link)
- Part 3 – Visual specifies a wide variety of visual descriptors such as colour, texture, shape, motion etc. (link)
- Part 4 – Audio specifies a wide variety of audio descriptors such as signature, instrument timber, melody description, spoken content description etc. (link)
- Part 5 – Multimedia description schemes specifies description tools that are not visual and audio ones, i.e., generic and multimedia description tools such as description of the content structural aspects (link)
- Part 8 – Extraction and use of MPEG-7 descriptions explains how MPEG-7 descriptions can be practically extracted and used
- Part 12 – Query format defines format to query multimedia repositories (link)
- Part 13 – Compact descriptors for visual search specifies a format that can be used to search images (link)
- Part 15 – Compact descriptors for video analysis specifies a format that can be used to analyse video clips (link).
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