Chapter 4: Metadata Magic 109 works over several kinds of media and platforms. However, it has mostly been targeted for use by professional multimedia creators. It has less relevance for user-level metadata in consumer created content – although the architecture does not exclude that use. 4.6.8 MPEG-7 40 MPEG-7 is part of the MPEG family of standards defi ned by the Motion Picture Experts Group within the ISO standardising organiza- tion. This standardizing body is responsible for defi ning many of the formats described elsewhere in this book, such as MP3 (more precisely: MPEG-1 Audio Layer 3). The standards from MPEG include MPEG-1 and MPEG-2 for audio and video compression, MPEG-4 for more complex audio and video documents with object-based composition, 3D rendering, interactivity, and other features, and MPEG-21 for handling digital multimedia items with integral copyright manage - ment throughout content production, distribution, and consumption chains. MPEG-7 is closely related to the domain of this book. It defi nes ways of expressing multimedia content metadata (not the content itself, as with MPEG 1, 2, and 4). This rich, ambitious framework defi nes a range of constructs such as descriptors, description schemes, defi nition languages, etc. – essentially all components of a complete metadata system (Manjunath et al. 2002). Moreover, the design of MPEG-7 seeks to ensure that the resulting descriptions are extensible, layered, embed- dable, streamable, distributable, semantically rich, and relevant to a wide range of applications. All these admirable goals have led the standard to appear complex by its design, probably refl ecting the complexity of the domain. No other multimedia standard succeeds in grasping as many conceptually demanding issues within one framework. This may also be a key weak- ness of the standard, as it appears to be suffi ciently rich to describe almost any existing and upcoming piece of multimedia. MPEG-7 tackles the apparent complexity by proposing profi les for specifi c applications, such as bibliographical references. Nevertheless, commercial support for the standard currently seems somewhat 41 modest, and development of the standard at the moment has ceased. 40 http://www.chiariglione.org/mpeg/ 41 http://www.chiariglione.org/mpeg/working_documents/mpeg-07/general/industry_ usage.zip