The next-generation of high-def is under rapid development, promising up to 16 times sharper images. Ian Calcutt reports on how the world’s first UHDTV broadcasts could begin soon.
The BBC and its Japanese counterpart NHK held free public demonstrations of Ultra High Definition Television (UHDTV) in the UK, US and Japan in July and August. The screenings were a chance to present this developing technology and included spectacular footage shot during the 2012 Olympics.
Both broadcasters have been working on the system, known in Japan under NHK’s brand name Super Hi-Vision (SHV). It’s described as “the future of television”, and anyone who saw the demos would hardly disagree. The format has an ‘8K’ resolution of 7,680 x 4,320 pixels – 16 times clearer than today’s HDTV broadcasts and double that used by ‘4K’ digital cinema projectors. The pin-sharp images are supported by immersive 22.2-channel surround sound.
In London NHK showed Hitachi’s lightweight camera prototype to the press. It has a single-chip sensor and no prism, bringing the weight for an SHV camera down from 20kg to 4kg, roughly the same as one for normal HD. Conventional lenses can also be used. A new single-point microphone enables 22.2-channel location audio recording.
These advances mean programme makers can shoot footage in a wide range of places, including news-gathering, which helps UHDTV become a more viable proposition. Super Hi-Vision may also be used for public screenings during the 2014 FIFA World Cup.
Improvements to video compression will be crucial to broadcasting in this format. Tests have been conducted by transmitting 8K Super Hi-Vision via satellite and a special high-speed internet connection. A successful terrestrial UHF test broadcast over a 4.2km distance was held in Tokyo earlier this year. NHK doesn’t plan to broadcast in 4K.
NHK’s Executive Director-General for Engineering, Dr Keiichi Kubota, said the company has been “investing a lot of time and passion in making Super Hi-Vision as close to reality as possible.”
The broadcaster set a target date of 2020 for public broadcasts to start in Japan but the rate of progress means that NHK is “already talking about moving the target date forward as soon as possible,” Dr Kubota revealed. “The speed of technological innovation is very fast now. I would be very happy if we could make it around 2016.”
For official broadcasts over greater distances NHK is considering the High Efficiency Video Coding system. H.265/HEVC is being devised by MPEG (Motion Picture Experts Group) as a replacement to H.264/AVC, which is widely used in digital video devices today. The new system aims to use half as much bandwidth as H.264.
This would all be in vain if there weren’t display products on which to see UHDTV. 4K TVs have been produced by LG and Toshiba, with others expected to follow. Prototypes exist by Panasonic (a 145-inch plasma) and Sharp (an 85-inch LCD screen), which can both show the full 8K resolution of Super Hi-Vision, as can purpose-built video projectors.
Consumer products should be ready in time for the start of 8K SHV broadcasts, though they will inevitably be premium-priced at first.
“When NHK started experimental HDTV broadcasting in the late 1980s we just provided one service for a limited time,” Dr Kubota told IER, “and the price of the first-generation HDTV receiver was ¥4m [tens of thousands of pounds]. It was very expensive but when we started digital HDTV 24-hours-per-day then the price dramatically went down. So it depends on what kind of service we can provide. If display manufacturers understand that NHK is serious about 8K broadcasting, they’ll decide to make commercial products that are affordable for the general public.”
The NHK team added that, anecdotally, viewers are more impressed by SHV than 3D, mainly because it is 2D taken to such a realistic quality. Doctors are said to have shown interest in using the technology and NHK has also introduced SHV into art galleries.
Outside of Japan, other broadcasters are free to work on UHDTV on their own timescale. SES-Astra, which operates satellites used for the UK and beyond, is getting ready too. Its president Romain Bausch told industry analysts in May that “NHK’s approach is for full 8K but the other UHDTV is 4K; we see this as being more commercially focussed and could be a reality only two or three years from now. BSkyB led the introduction of HDTV in Europe so do not be surprised if you see us partnering with BSkyB to pioneer the introduction of UHDTV. SES is well prepared, and as soon as our customers are ready we are ready.”