Workflow Support for Live Object-Based Broadcasting

This paper examines the document aspects of object-based broadcasting. Object-based broadcasting augments traditional video and audio broadcast content with additional (temporally-constrained) media objects. The content of these objects - as well as their temporal validity - are determined by the broadcast source, but the actual rendering and placement of these objects can be customized to the needs/constraints of the content viewer(s). The use of object-based broadcasting enables a more tailored end-user experience than the one-size-fits-all of traditional broadcasts: the viewer may be able to selectively turn off overlay graphics (such as statistics) during a sports game, or selectively render them on a secondary device. Object-based broadcasting also holds the potential for supporting presentation adaptivity for accessibility or for device heterogeneity. From a technology perspective, object-based broadcasting resembles a traditional IP media stream, accompanied by a structured multimedia document that contains timed rendering instructions. Unfortunately, the use of object-based broadcasting is severely limited because of the problems it poses for the traditional television production workflow (and in particular, for use in live television production). The traditional workflow places graphics, effects and replays as immutable components in the main audio/video feed originating from, for example, a production truck outside a sports stadium. This single feed is then delivered near-live to the homes of all viewers. In order to effectively support dynamic object-based broadcasting, the production workflow will need to retain a familiar creative interface to the production staff, but also allow the insertion and delivery of a differentiated set of objects for selective use at the receiving end. In this paper we present a model and implementation of a dynamic system for supporting object-based broadcasting in the context of a motor sport application. We define a new multimedia document format that supports dynamic modifications during playback; this allows editing decisions by the producer to be activated by agents at the receiving end of the content. We describe a prototype system to allow playback of these broadcasts and a production system that allows live object-based control within the production workflow. We conclude with an evaluation of a trial using near-live deployment of the environment, using content from our partners, in a sport environment.