Introduction

We have created a broadcast standard and system which allows broadcasters to group related programmes together and transmit this additional metadata alongside existing digital TV services. Transmitting fragmented and packaged XML over-air allows us to describe lists of related programmes such as “Best of BBC Comedy” or “Mozart Season”. Viewers can subscribe to each list if they think it looks interesting, and their receiver will then identify programmes belonging to that list and record them.

What we're doing

We worked with other broadcasters, receiver manufacturers and the DTG to create a D-Book specification for the transmission of TV-Anytime XML metadata in transport streams in order to carry this new metadata.

We profiled the additional metadata to provide a set of viewing facing metadata that allows viewers to make a choice on whether or not to subscribe to a list.

We also worked with a small number of manufacturers to prototype the new service to ensure that a workable specification had been produced and that a good viewer experience is provided.

On behalf of Digital UK, we helped design the system architecture and test the transmission equipment and ensured the signalling conforms to the D-Book specification when it went on air. A trial service is now available from all DTT transmitters.

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Why it matters

Existing Freeview+ specifications, used mainly by PVRs, allow for series linking but what if content could be linked together where it is not in a series, or is broadcast across different media types (TV, Radio, Interactive)? There has been a desire for some time to be able to relate programmes together into the BBC’s broad genre categories, into specials seasons of work or grouped around flagship events. This will make it as easy as possible to find more of what you want to watch. Being built on an extensible standard, it will also pave the way for future updates on Digital Terrestrial in the UK.

How it works

The standardisation of this technology came in two parts. Firstly, we had to reach agreement on how we format the metadata itself. Rather than attempt to define a new DVB tables we instead decided to use TV-Anytime XML, as this is more flexible and allows future extensibility. We worked with receiver manufacturers to decide which parts of the TV-Anytime schema should be used, and how the receiver should interpret the new metadata. Secondly we needed to agree on a way of carrying this XML in an existing broadcast multiplex. Using existing ETSI standards as a starting point, we standardised a method by which large XML documents could be split into a number of more manageable sized fragments.

These fragments are placed in a DSM-CC object carousel before being multiplexed into the main transport stream.

Once we were satisfied that the specification was correct and complete, we worked with Digital UK, who manage the transmission of platform metadata in the UK, to agree the method by which broadcasters will feed their metadata to a centralised aggregation system. It is this aggregation system that creates the XML and places it into a very low bitrate DSM-CC carousel, which is finally multiplexed into existing multiplexes ready for transmission.

Partners

People and partners

Project team