MUSCLE - Analysis of open problems and interoperability limits of existing standards and tools

In the context of the MUSCLE (Multimedia Understanding through Semantics, Computation and Learning) Network of Excellence, this document firstly introduces the mostly and commonly used MM metadata standards and tools highlighting the main reasons why they have been introduced, or created from other previously existing standards, in order to point out the reference framework of the project. Then, a discussion is presented about the open problems regarding MM metadata integration and interoperability from a semantic point of view, also related to the available technologies.