Semantic annotation of media resources has been a focus in research since many years, the closing of the "semantic gap" being seen as key to signicant improvements in media retrieval and browsing and
enabling new media applications and services. However, current tools and services exhibit varied approaches which do not easily integrate and
act as a barrier to wider uptake of semantic annotation of online multimedia.
In this paper, we outline the Linked Media principles which can help form a consensus on media annotation approaches, survey current media annotation tools against these principles and present two emerging
toolsets which can support Linked Media conformant annotation, closing with a call to future semantic media annotation tools and services to follow the same principles and ensure the growth of a Linked Media
layer of semantic descriptions of online media which can be an enabler to richer future online media services.