Chapter 4: Metadata Magic 91 iTunes, and quite rarely hears any bad pieces anymore. But if she goes for Winamp, all those ratings seem to be lost. Wouldn’t you know it, just after installing Winamp it started – most embarrass- ingly – playing her forgotten Backstreet Boys disks. Eddie said nothing but did raise his eyebrows disapprovingly. Well, now those fi les are gone, but shouldn’t there be a way to export ratings from iTunes to Winamp? After a few days of fi ddling with Winamp, Angie gives up. She will stick with iTunes. She’s got so much content already in that library that she could not be bothered to switch. Maybe Eddie could get an iTunes converter for his precious playlists? In addition to mere insertions, metadata maintenance will also include deletion, in case of false or outdated metadata, or due to privacy reasons, and refi nement such as analyzing metadata to make further assumptions. When metadata is transformed between different systems, or when fi les are converted from one format to another, the metadata may have to be translated too. Often different systems have different naming conventions for similar metadata attributes, or the interpretation of the attributes differ between the systems. Metadata is more than just attributes. An important source of infor- mation comes from inspecting content objects and fi nding similarities and other relations between them. Next, we will discuss the impor- tance of relations as a form of metadata. 4.4 Relations Give Meaning Object-level relations are essential building blocks for exploiting meta- data for the user’s benefi t. Metadata is often seen as attributes of content objects, but there is also valuable information in the relations between the objects. For example, a song is part of an album, a book refers to another book, and an actor is starring in a fi lm. Once we know the relations, we can trace the object networks that are formed by these links. Such networks will not only reveal items that are somehow related to the object at hand, but can be used in a number of ways to gain new information on the present object. Relations then give context and meaning to objects. Relations also enable associative browsing, helping the user to fi nd objects that are logically connected in some way. In some simple cases, relations allow constructing playlists, slide- shows, or other one-dimensional collections. In more advanced cases, through the analysis of multiple content items, they can be exploited to construct automatic or semi-automatic stories about past events and