Frame-accuracy synchronisation for mobile TV interactivity

Interactive applications for mobile TV are usually related to the audiovisual content, but not very precisely. In some applications, like object-based interactivity, where the user can retrieve rich media information associated to moving objects with just the direct interactivity by the touch screen of the mobile device, frame-based precision is required. As DVB-H transmits audiovisual content in MPEG-4 formats, the natural choice for adding rich content seems to be LASeR (MPEG-4 part 20) scene description. In this paper we present a mechanism to achieve frame-accuracy synchronisation between audio, video and LASeR streams. We also introduce its inclusion to an end-to-end system that implements the whole chain of creation, transmission and reception of interactive applications for mobile devices.