So, back on the old XMP tack. The simple vision from the XMP spec is that XMP packets are embedded in media files and transported along with them - and as such are relatively self-contained units, see Fig 1.
Fig. 1 - Media files with fully encapsulated descriptions.
But this is too simple. Some preliminary considerations lead us to to see why we might want to reference additional (i.e. external) sources of metadata from the original packet:
- PDFs
- PDFs are tightly structured and as such it can be difficult to write a new packet, or to update an existing packet. One solution proposed earlier is to embed a minimal packet which could then reference a more complete description in a standalone packet. (And in turn this standalone packet could reference additional sources of metadata.)
- Images
- While considerably simpler to write into web-delivery image formats (e.g. JPEG, GIF, PNG), it is the case that metadata pertinent to the image only is likely to be embedded. Also, of interest is the work from which the image is derived which is most likely to be presented externally to the image as a standalone document. (And in turn this standalone packet could reference additional sources of metadata.)
(Continues)
