TV delivery: UHD is object of DPP18 September 2015
New television delivery and production formats have developed over recent years but now broadcasters are faced with a shift to higher tech ways of working more quickly than might have been expected. Connectivity and transfer of audio and video over IP (AoIP and VoIP) are being consolidated; Ultra High Definition (UHD) services have been implemented in India and the UK, with Germany to follow this month. All this is happening before international standards have been put in place, with sound in particular still an issue to be fully decided. National trade bodies are offering interim advice, with the British Digital Production Partnership (DDP) issuing three new guides during this August.
The DPP was formed by the BBC, ITV and Channel 4 to agree specifications and guidelines for the delivery of tapeless, data-based programmes to UK broadcasters. It has produced advisory documents for SD and HD productions, covering audio considerations such as loudness. The three new reports are: Ten Things You Need To Know About Connectivity; Ten Things You Need To Know About Ultra High Definition; and Home Truths No.1: Reaching Nirvana over IP, a report from the first DPP At Home event, where 30 industry figures discussed the claims being made for IP-based production and broadcast.
The reports are the first to be issued since 1 April, when the DPP became a not-for-profit limited company. “The DPP’s mission is to help the broadcasting industry by easing the transition to digital workflows,” comments DPP managing director Mark Harrison. “These three publications show the quality of the industry [and the] wide expertise the DPP can pull together. They will be an invaluable resource for our members.”
UHD is the most obviously pressing technology area where producers, broadcasters and facilities need guidance. The DPP report on the subject describes the technology, lists the relevant technical terms and outlines what effects it will have on TV production. This includes the main visual selling points of UHD: bigger pictures, higher frame rates and dynamic range and wider colour gamut. On the audio side, the situation is less clear. Although NHK’s 22.2 format has long been linked to 4K and 8K and recent tests of UHD have featured 5.1, the current guidelines suggest only stereo as the sound partner.
This perhaps should not be seen as too shocking. Speaking to PSNEurope on behalf of the DPP, Andy Quested, the BBC’s head of technology for HD and UHD, points out that there was no set audio standard for HD but 5.1 became a major part of the format. The BBC has decided on 5.1 as the minimum requirement for its UHD productions. “There is a big gap where audio is concerned, although it is closing,” Quested (pictured top) comments. “5.1 is the minimum for delivery of high-end programmes through BBC Worldwide. These are only interim guidelines while we’re working with the DPP but stereo isn’t good enough to meet audience expectations.”
The ultimate aim with UHD is to have some form of immersive surround sound, including a sensation of height as well as width and length. There were always doubts about implementing 22.2 because of the number of loudspeaker channels involved. Quested observes that even NHK is beginning to question the viability of the format for production. “We need to find a more efficient way to deliver surround,” he says. “Fixed channels are not viable in terms of production. On something like the Olympics there are many sources from various locations. These could have different options when they arrive at the sound desk and each would have to be reproduced as 22.2. Some sources will be pre-mixed but there still won’t be enough faders. We have to think differently about that and how the audience hears the sound.”
For these early stages of UHD, Quested says there will be no changes to the audio requirements. “But in the second phase, when the standards have settled down, there needs to be a move away from channel-based operation to objects,” he says. “There will have to be some form of object-based descriptor for how the signals being delivered to the home are decoded. SMPTE and the ITU are looking at this for mapping and are moving away from channels. If we start with 5.1 and then move to objects that will be easier.”
While films and high-end drama and documentaries are clear beneficiaries of immersive sound, Quested points out that not all programmes will require some form of enhanced surround: “As we move into object-based spatial audio there will be anything from two speakers up to infinite. But there are other issues to consider, such as audibility. We have an aging population and we have to be careful with a flexible approach because we don’t want to upset the audience. What is good sound for people who know about and work in audio can be bad for everyone else.”
The DPP reports can be downloaded from the organisation’s websites. Further publications on UHD and the other subjects are planned for later in the year.