“Combining new CMAF and Low Latency technologies into a single low-latency format for an optimal live experience.”
While streaming audiovisual content may look simple to consumers, in reality, there are a number of complex technical stages and challenges that it has to go through before it reaches its destination at the highest quality.
Put simply, the distribution of live and on-demand audiovisual content involves a range of technologies, including those to compress the audiovisual data, before it can be sent through the appropriate distribution protocol depending on the transmission mediums used — such as 4G, 5G or fibre.
New uses and services
Increased connectivity across all networks has allowed new use cases to be identified and innovative audiovisual services to be developed in response with 5G networks at the forefront of this change. At Orange, innovation teams are leading projects in this area with two objectives.
“On the one hand, it’s about identifying solutions that can improve service quality for live TV services using 5G, and making them work for 4G networks to optimise what’s already there”, explains Emmanuel Gouleau, Service Architect at Orange.
“On the other hand, we’re developing audiovisual services that really take advantage of the increased speeds we see with 5G, such as immersive and 360° content. This type of content will be available on the move with 5G as it is currently, at 3.6 GHz, but will increase in spectrum over time to 26 GHz in busy public places.”
Optimising the transport channels
Alongside and in line with 5G developments, Orange’s Research teams are monitoring the tools and standards that govern content distribution, from encryption to transport, including taking part in ecosystem standardisation bodies such as the Moving Picture Expert Group (MPEG), which looks at video file compression, and the International Telecommunication Union (ITU). The related technical environment is dense and constantly evolving, with new transport formats and compression technologies emerging on a regular basis.
When it comes to transport in particular, there are currently two coexistent and traditional technical channels. “Internet Protocol television (IPTV) is primarily used for live content watched exclusively on set-top boxes, and quality is guaranteed”, explains Sylvain Kervadec and Pierre Ruellou, expert engineers at Orange Innovation. “Over-the-top (OTT), on the other hand, distributes content to mobile devices via the Internet, and does not offer any bandwidth guarantees. For these OTT technologies, we use adaptive streaming, which causes latency in live content. Our aim is to reduce this delay by working on the transport layer of audiovisual signals, with the implementation of new protocols and technologies. This primarily involves Low Latency and Common Media Application Format (CMAF), which will enable us to move towards one single format for all devices instead of the different transport methods currently required for the Android and iOS systems. The perfect solution would be combining CMAF and Low Latency into a single low-latency format for an optimal live experience resembling what you get with IPTV. We’re also working to bring these new OTT formats to set-top boxes to replace IPTV.”
Ever-increasing compression capabilities
Compression is another area where innovation is ongoing and we are seeing regular developments. The standards evolve every ten years on average, with a twofold gain each time. In other words, the same quality data travels twice as quickly — a key development given the explosion of traffic and the emergence of new 4K/8K and virtual reality use cases, which are extremely intensive in terms of video capabilities. Today, the standard in place for services up to high definition is the MPEG-4 Advanced Video Coding (AVC, or H.264 as it is referred to by the ITU Telecommunication Standardization Sector). Orange has used the MPEG-H High Efficiency Video Coding (HEVC or H.265) standard, which emerged in 2013, in the last two generations of set-top boxes, allowing new ultra-high definition/4K services to be introduced. A further barrier was broken in 2020 with the MPEG-I Versatile Video Coding (VVC or H.266) codecs increasing performance compared to those that came before. Studies are to be conducted within the Group to assess the efficacy of these new technologies, as well as their impact on the existing ecosystem and their potential for the future of audiovisual services.
Multicast ABR testing
One final key issue is the need to optimise bandwidth in line with these different developments. Today, in the world of IPTV, content is delivered in the form of multicast streams — in other words, it only needs to be transmitted to the network once to be made available to millions of viewers. The OTT universe works based on unicast transmission, whereby content has to be delivered once for every person that wants to watch it, reducing transmission speeds. Orange’s innovation teams are working to streamline this method by experimenting with Multicast Adaptive Bitrate (ABR) streaming technology. If successful, this would allow multicast capabilities to be deployed in OTT services using devices as close as possible to the customer. The future is bright for the distribution of audiovisual content.