mABR Archives – The Broadcast Knowledge

Multicast ABR (mABR) is a way of delivering traditional HTTP-based streams like HLS and DASH over multicast. On a managed telco network, the services are multicast to thousands of homes and only within the home itself does the stream gets converted back unicast HTTP. Devices in the home then access streaming services in exactly the same way as they would Netflix or iPlayer over the internet, but the content is served locally. Streaming is a point-to-point service so each device takes its own stream. If you have 3 devices in the home watching a service, you’ll be sending 3 streams out to them. With mABR, the core network only ever sees one stream to the home and the linear scaling is done internally. Not only does this help remove peaks in traffic, but it significantly reduces the load on the upstream networks, the origin servers and smooths out the bandwidth use.

This video from DVB lays out the business cases which are enabled by mABR. mABR has approved the specification which is now going for standardisation within ETSI. It’s already gained some traction with deployments in the field, so this talk looks at what the projects that drive the continued growth in mABR may look like.

Williams Tovar starts first by making the case for OTT over satellite. With OTT services continuing to take viewing time away from traditional broadcast services, satellite providers are working to ensure they retain relevance and offer value. Delivering these OTT services is, thus, clearly beneficial, but why would you want to? On top of the mABR benefits briefly outlined above, this business case recognises that not everyone is served by a good internet connection. Distributing OTT by satellite can provide high bitrate, OTT experiences to areas with bad broadband and could also be an efficient way to deliver to large public places such as hotels and ships.

Julian Lemotheux from Orange presents a business case for next-generation IPTV. The idea here is to bring down the cost of STBs by replacing CA security with DRM and replacing the chipset with a cheaper one which is less specialised. As DASH and HLS streaming are cpu-based tasks and well understood, general, mass-produced chipsets can be used which are cheaper and removing CA removes some hardware from the box. Also to be considered is that the OTT ecosystem is continually seeing innovation so delivering services in the same format allows providers to keep their offerings up to date without custom development in the IPTV software stack.

Xavier Leclercq from Broadpeak looks, next, at Scaling ABR Delivery. This business case is a consideration of what the ultimate situation will be regarding MPEG2 TSes and ABR. Why don’t we provide all services as Netflix-style ABR streams? One reason is that the scale is enormous with one connection per device, CDNs and national networks would still not be able to cope. Another is that the QoS for MPEG2 transport streams is very good and, whilst it is possible to have bad reception, there is little else that causes interruption to the stream.

mABR can address both of these challenges. By delivering one stream to each home and having the local gateway do the scaling, mass delivery of streamed content becomes both predictable and practical. Whilst there is still a lot of bandwidth involved, the predictable load on the CDNs is much more controlled and with lower peaks, the CDN cost is reduced as this is normally based on the maximum throughput. mABR can also be delivered with a higher QoS than public internet traffic which allows it to benefit from better reliability which could move it in the realm of the traditional transport-stream based serviced. Xavier explains that if you put the gateway within a TV, you are able to deliver a set-top-box-less service whilst if you want to address all devices in you home, you can provide a separate gateway.

Before the video finishes with a Q&A session, Williams delivers the business case for Backhauling over Satellite for CDNs and IP backhaul for 5G Networks. The use case for both has similarities. The CDN backhauling example looks at using satellite to efficiently deliver directly to CDN PoPs in hard to reach areas which may have limited internet links. The Satellite could deliver a high bandwidth set of streams to many PoPs. A similar issue presents itself as there is so much bandwidth available, there is a concern about getting enough into the transmitter. Whether by satellite or IP Multicast, mABR could be used for CDN backhauling to 5G networks delivering into a Mobile Edge Computing (MEC) cache. A further benefit in doing this is avoiding issues with CDN and core network scalability where, again, keeping the individual requests and streams away from the CDN and the network is a big benefit.

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Speakers

	Williams Tovar Soultion Pre-sales manager, ENENSYS Technologies
	Julien Lemotheux Standardisation Expert, Orange Labs
	Xavier Leclercq VP Business Development, Broadpeak
	Moderator: Christophe Berdinat Chairman CM-I MABR, DVB Innovation and Standardisation Manager, ENENSYS

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With video delivery constituting the majority of traffic, it’s clear there’s a big market for it. ON the internet, this is done with unicast streaming where for each receiver, the stream source has to send another stream. The way this has been implemented using HTTP allows for a very natural system, allied Adaptive Bit Rate (ABR), which means that every when your network capacity is constrained (by the network itself or bandwidth contention), you can still get a picture just at a lower bit rate.

But when extrapolating this system linear television, we find that large audience place massive demands on the originating infrastructure. This load on the infrastructure drives its architects to implement a lot of redundancy making it expensive to run. Within a broadcaster, such loads would be dealt with by multicast traffic but on the internet, Multicast is not enabled. For an IPTV system where each employee had access via a program on their PC and/or a set-top-box on their desk, the video would be sent by multicast meaning that it is the network that was providing the duplication of the streams to each endpoint, not the source.

By combining existing media encoding and packaging formats with the efficiency of point-to-multipoint distribution to the edge of IP-based access networks, it is possible to design a system for linear media distribution that is both efficient and scalable to very large audiences, while remaining technically compatible with the largest possible set of already-deployed end user equipment.

This webinar by Guillaume Bichot which is in place of his talk at the cancelled DVB World 2020 event explains DVB’s approach to doing thus that; combining multicast ordination of content with delivery of an ABR feed, called DVB-mABR.

Video broadcast has been digitised since it’s initial broadcasts in the 30s, and more than once. In Europe, we have seen IP carriage (IPTV) services and most recently the hybrid approach where broadband access is merged into transmitted content with the aim of delivering a unified service to the viewer called HbbTV. Multicast ABR (mABR) defines the carriage of Adaptive Bit Rate video formats and protocols over a broadcast/multicast feed. Guillaume explains the mABR architecture and then looks at the deployment possibilities and what the future might hold.

mABR comprises a multicast server at the video headend. This server/transcaster, receives standard ABR feeds and then encapsulates it into multicast before sending. The decoder does the opposite, removing any multicast headers revealing the ABR underneath. It’s not uncommon for mABR to be combined with HTTP unicast allowing the unicast to pick up the less popular channels but for the main services to benefit from multicast.

Guillaume explores these topics plus whether mABR saves bit rate, how it’s deployed and how it can change in the future to keep up with viewers’ requirements.

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