Development of MMT-based broadcasting system for hybrid delivery

An UHDTV broadcasting system employing MPEG Media Transport (MMT) as its media transport protocol has been proposed for hybrid delivery of content. On the basis of this proposal, an MMT-based UHDTV broadcasting system has already been standardized and is being developed in Japan. This paper describes the structure of that system. The system supports hybrid delivery and has mechanisms to carry Universal Time Coordinated (UTC) information to eliminate clock drift between the sender and receiver. We evaluated the delay variation of UTC information through the use of a broadcast modulator/demodulator we developed and proved that it is small enough. We also conducted an experiment through an actual broadband network to confirm the functionality of hybrid delivery. The experimental results show that audio/video signals could be presented in synchronization with each other even though they are delivered separately over broadcast channels and broadband networks.