Advanced interactive television services require content synchronization

Advanced interactive television services, e.g. using IMS-based IPTV technology, enable users to interact with other users within the context of simultaneously consumed content, like broadcast television channels. Differences of content arrival time of 100 ms may already have a perceivable effect on such interaction. Measurements presented in this paper show that these differences can be orders of magnitudes larger in practical systems. The main sources of delay are coding and decoding delays, but also multicasting can introduce significant delay differences. The paper concludes with architectural approaches to inter-destination content synchronization, which can be network- and terminal based. Standardization will be needed in order to make content synchronization solution interoperable between different vendors and service providers.