In this paper an authoring tool for the MPEG-4 multimedia standard integrated with image sequence analysis algorithms is described. Bringing much new functionality, MPEG-4 offers numerous capabilities and is expected to be the future standard for multimedia applications. However, the implementation of these capabilities requires a complex authoring process, employing many different competencies from image sequence analysis and encoding of Audio/visual/BIFS to the implementation of different delivery scenarios: local access on CD/DVD-ROM, Internet or broadcast. As multimedia system history teaches, however powerful the technologies underlying multimedia computing, the success of these systems depends on their ease of authoring. In this paper a novel authoring tool fully exploiting the object-based coding and 3D synthetic functionalities of the MPEG-4 standard is described. It is based upon an open and modular architecture able to progress with MPEG-4 versions and it is easily adaptable to newly emerging better and higher-level authoring and image sequence analysis features. The authoring tool is available for download from our web site: http://uranus.ee.auth.gr/pened99/Demos/ Authoring Tool/authoring tool.html