A method or system configured for receiving a first single data stream representing a first multimedia file, the first single data stream including an interleaved sequence of data elements of a plurality of media, and/or transmitting a second single data stream representing a second multimedia file, the second single data stream including an interleaved sequence of data elements of said plurality of media, where the second multimedia file differs from said first multimedia file by at least one data element of a selected medium extracted from said first multimedia file, and/or by at least one data element of a selected medium added to the first multimedia file, and/or by at least one data element of a selected medium added to the first multimedia file being a converted version of the at least one data element of a selected medium extracted from the first multimedia file.