DVB over IP: The building blocks12 September 2014
Over the past few years, Over-The-Top (OTT) has been the hot topic; and it has woken up – if not shaken up — the players in the broadcast industry. But as often, the reports of the death of broadcast have been greatly exaggerated; OTT hasn’t taken over the market just yet, and it doesn’t seem it is going to this year either.
But broadcasters have learnt from the OTT hype that IP-based technologies, beyond being a threat by enabling new players in the entertainment space, can also play a positive role in their own portfolios. As first steps in embracing them, we have seen broadcasters rollout catch-up archives and HbbTV apps.
Technically, the foundations for all these are web technologies. The underlying IP networking technology however has a lot more to offer than serving as a transport for HTTP. OTT and IPTV remain segmented, with no signs of any technological convergence.
Thinking about standardised solutions centered around web technologies, I am often asked what DVB has done – if anything – in this area. So let’s have a look at those individual DVB technologies and solutions that have already been designed with IP, the internet, and the web in mind.
Physical and link layer
The second generation of DVB modulation schemes with DVB-S2, DVB-T2, and the recent releases of DVB-C2 and DVB-NGH have certainly generated the most buzz in the DVB space recently. Of course they are spectacular by making new HDTV and UHDTV use cases commercially viable, thanks to their tremendous increase in link capacity.
But they also brought a no less important innovation: in addition to MPEG-2 Transport Stream, they all provide a Generic Stream (GS) mode, which is used by DVB-GSE, the Generic Stream Encapsulation. DVB-GSE is a link layer for carrying IPv4, IPv6, and other networking protocols as its payload, and enables routing of IP multicast streams from any other networking infrastructure over DVB systems.
DVB-GSE also defines a Logical Link Control protocol enabling auto-configuring receivers and dynamic network management by in-band signaling of the RF and network configurations of the links in the broadcast network. That way, IPTV-like systems can easily be built on DVB broadcast infrastructure.
Combined with a suitable return channel emulation (see Figure 1), even existing IPTV systems can easily be deployed over DVB infrastructure. Such scenarios are currently studied with great interest in the cable industry.
For managed IP networks, the DVB-IPTV suite of specifications enables rich IPTV services by allowing for auto-configuring receivers (Service Discovery and Selection, SDnS), efficient use of precious network resources with error-free multicast transport and hands-free management of the installed receiver base. The recent release of the DVB profile of MPEG-DASH allows for a low-cost receiver, and the content provisioning efforts for web streaming and catch-up archives will also largely be reduced.
Needless to say that of course all IP-related DVB technologies already support IPv6 out of the box. Whatever 4-to-6 transition strategy you have chosen, or will choose, your investments will be safe with DVB.
The DVB-IPTV suite of specifications comes with content delivery modes for Live Media Broadcast (LMB), and for Content on Demand (CoD). The content offering can be discovered in a rich, searchable, linkable, and inter-linked content guide. To enable a hybrid delivery network consisting of both MPEG-2 TS and DVB-IPTV infrastructure, and offering rich content flexibly across both platforms, the DVB profile of TV-Anytime forMPEG-2 TS is defined as a compatible subset of the IPTV content guide.
Receivers can retrieve the content from wherever it currently happens to be available: MPEG-2 TS, IPTV live streaming, IPTV on demand, or the web. To support interactive apps like eg. DVB-GEM, or HbbTV to access broadcast and IPTV resources from a browser environment, we have further defined the ‘dvb’ URI scheme. This enables web browsers e.g. on Connected TVs to allow web pages to access broadcast resources via hrefs beginning with “dvb://”.
Overall, we are proud to say that specifications for DVB over IP are available across the board and deployed in the market (see Figure 2). At DVB we are keeping a close eye on how things develop, and are constantly evaluating with our members to determine when it’s time for taking things to the next level.
We also take pride in protecting your investments in DVB technology by maintaining compatibility with previous versions and making sure viable migration paths exist. So wherever DVB will be going in the future, you will be able to follow us and continuously take advantage of the most deployed TV standard in the world.