5G-Xcast partners have contributed to a DVB Blue Book reference for delivering Adaptive Bit Rate unicast content over a multicast network. In unicast HTTP delivery, ABR content is pulled by devices as individual streams at variable rates. Multicast by contrast is fixed-rate, and a single stream is pushed to multiple devices, offering increased efficiency when delivering popular content to many simultaneous viewers. To deliver ABR via multicast, the individual media files need to be encapsulated into other protocols, so that they can be recovered as discrete files again when they exit the continuous multicast pipe at the residential gateway. Media signalling, service discovery, media caching and error protection are also required.
The DVB TM-IPI working group have now released their reference architecture as a publication known as a Blue Book for consultation https://www.dvb.org/news/dvb-releases-reference-architecture-for-ip-multicast, prior to its ratification by ETSI as a standard, and in parallel, continue to work on the necessary media encapsulation recommendations.
The work began with a 15 month exercise in the DVB Commercial Module to collect use cases from industry and content providers, and to refine these into a set of commercial requirements. Approved in December 2016, these requirements were passed to the DVB Technical Module to define a reference architecture, with the Blue Book subsequently published in March 2018.
The five 5G-Xcast partners involved at either the Commercial or Technical stages in contributing to this work are BBC R&D, Broadpeak, BT, Nokia and Samsung.
