BT Group is proposing a new online video technology it has called Multicast-Assisted Unicast Delivery or MAUD. It says that major broadcasters, including the BBC, will be involved in evaluating and potentially trialling the technology for a range of live events in 2024.

Multicast has long been presented as the solution to delivering live media over data networks. It is widely used in IPTV networks and has been supported in mobile network standards for a decade.

The problem is that multicast does not currently play well with the open internet and home networks, particularly wireless networks, although that it more a problem of implementation and support.

The BT implementation proposes to use multicast to deliver live streams but convert them to unicast at the consumer router through what is called an edge proxy. It says this means that integration is completely transparent to the player application.

Howard Watson, the chief security and networks officer at BT Group said: “MAUD is a major breakthrough in how we deliver content over the internet.”

Developed by the Content Delivery Research team at BT Labs at Adastral Park in Suffolk, the goal was to create a solution for efficient live streaming that was sensitive to the needs of the various organisations in the content delivery path.

The MAUD solution was presented to broadcasters in a paper delivered at the IBC conference in Amsterdam. The audience of engineers was largely bemused by the solution, which works by distributing the main media payload over the network using multicast but presents this to end user applications as a unicast stream, meaning that the app will continue to make requests for media as if it were dealing with a normal adaptive bitrate source.

The supposed benefit of this approach is that it does not require media companies to change their apps, although they will still have to make changes to their delivery systems.

The problem is that it requires consumers to change their routers. At the time, the technology had only been tested with a network of 90 Raspberry Pi computers and was not implemented or deployed in any consumer routers. However, it was apparently tested on a next-generation BT home gateway development system.

The MAUD approach is also not an international standard, so it is currently proprietary to BT, which means that it will only work over the BT network for customers of BT, or EE as they are now known to consumers.

In fact, the MAUD approach is very similar to a standard developed by the DVB project for multicast adaptive bitrate delivery, with a couple of key differences. Notably, it retains a role for content delivery network providers. BT performed its trial with one of them, Qwilt.

Although multicast may have a role in the efficient online delivery of linear channels, it does not address a key benefit that commercial broadcasters see in this, which is the ability to address targeted advertising to distinct groups of users.

Presenting multicast services as unicast streams could potentially support this, but it does not provide a complete solution.

While delivery of media streams is one thing, there remain issues around resolving digital rights management licences and other aspects of entitlements, which can also present problems when scaling services to very large numbers of users for high-profile events.

Unless this becomes viable solution for the whole market, it seems that media providers would need to support a separate delivery system for BT customers, while continuing to support their existing content delivery network solutions for other users.

That is not to say that the BT approach is without merit, but it is not without its problems either.