This invention relates to efficiently performing a close-duplicate search within large collections of data streams, preferably in the context of Multimedia (audio and video files or streams). In a first aspect the present invention relates to a method for feeding information of a data from a data file or a data stream into a database. In a second aspect a method is provided for tagging or identifying a data stream by querying an unknown data or data stream to a database of known data streams. In a third aspect a computer program or suite of computer programs are provided to operate the methods of this invention. The robustness of the Multimedia Identifier system of the present invention results from the use of high-dimensional descriptors, which describe local interest points extracted from the frames of audio and/or video data.
