Multiple exhibition devices in DTV systems

摘要

Nested Context Language (NCL) is the declarative language of the Brazilian Terrestrial Digital TV System. NCL is part of ISDB (International Standard for Digital Broadcasting) standards and also the ITU-T Recommendation H.761 for IPTV services. This paper presents, discusses, and illustrates the NCL hierarchical control model for multiple exhibition device support. Based on this model, multiple devices are orchestrated to run a DTV application in cooperation. Two types of multiple device exhibitions are distinguished. Those where the same content is shown in a set of devices under a unique control, and those where content is under each individual device control, working completely independent. In this last case, depending on viewer interactions, the resulting presented content can differ from a device to another. Examples of NCL applications using both options are presented and discussed.