Metadata-driven optimal transcoding in a multimedia proxy

An adaptive multimedia proxy is presented which provides (1) caching, (2) filtering, and (3) media gateway functionalities. The proxy can perform media adaptation on its own, either relying on layered coding or using transcoding mainly in the decompressed domain. A cost model is presented which incorporates user requirements, terminal capabilities, and video variations in one formula. Based on this model, the proxy acts as a general broker of different user requirements and of different video variations. This is a first step towards What You Need is What You Get (WYNIWYG) video services, which deliver videos to users in exactly the quality they need and are willing to pay for. The MPEG-7 and MPEG-21 standards enable this in an interoperable way. A detailed evaluation based on a series of simulation runs is provided.