BBC starts Ultra-HD trials
The BBC has started its Ultra-HD closed trials from the World Cup tournament in Brazil. The BBC Research & Development department has partnered with Arqiva for the trials that will use the latest DVB-DASH profile IP.
In a blog post Phil Layton, Head of Broadcast & Connected Systems at the BBC, outlined what the trials aim to achieve and how they will be executed.
He wrote: “Recently BBC R&D announced our intention to trial the distribution of Ultra-High definition programming over both DTT and IP. Over the coming few weeks I would like to share with you some more technical details of the trial.
BBC R&D is actively working on Ultra-High Definition (UHD) in the various standardisation bodies. The World Cup gives us an ideal opportunity to practically test out some of that work. We set ourselves the goal of demonstrating an end-to-end live UHD broadcast over both a traditional DVB network and an adaptive bitrate delivery approach over IP. To do this we have partnered with Arqiva on the DTT side and will use existing super-fast broadband infrastructure for IP delivery. In a later post we will detail the chain we have constructed and the contribution from numerous other companies we’ve collaborated with and who have provided essential equipment.
The UHD production will be received in the UK from an H.264/AVC satellite contribution feed. For both DTT and IP we will be using Main Profile HEVC to compress the video to distribution bitrates that can be sustained within a DVB network and a super-fast broadband line. The frame rate being used is 59.94Hz as that is the standard in Brazil.
The DTT trial will be transmitted from Crystal Palace (London), Winter Hill (Manchester) and Black Hill (Glasgow). The transmissions are just starting up now. As we are using the same T2 modulation parameters that are used for HD multiplexes the signal can be received on current consumer equipment, I’m not aware of any equipment which can decode the video. Though some existing HD models may tune the service and decode the audio.
The stream will use the latest DVB-DASH profile and is geo-IP locked to the UK only.
Our experience so far is that dedicated hardware is required to be able to decode Ultra-High Definition HEVC encoded video. In conjunction with some consumer equipment vendors, we will be using some of the latest chipsets from the silicon suppliers.
Part of the experiment will be to understand the performance of the newly launched HEVC encoders so the video bitrates are very much subject to change but I think we will end up at around 30-35Mbit/s.
BBC R&D has a long history of research in this area reaching back to our white paper back in 2004 and to our Super-Hi-Vision demonstrations during the London 2012 Olympics. More recently we have written about some of the challenges faced around frame rates and resolution.”