This paper deals with the problem of finding multimedia data that fulfill the requirements of user queries. We assume both the user query and the multimedia data are expressed by MPEG-7 standard. The MPEG-7 formalism lacks the semantics and reasoning support in many ways. For example, the search of the implicit data can not be achieved, due to its description based on XML schema. We propose a framework for querying multimedia data based on a tree embedding approximation algorithm, combining the MPEG-7 standard and an ontology.