28 Friday 13.09.13 theibcdaily I’m UHDTV, get me out of here
After the agreement on UHDTV in ITU BT. 2020, David Wood, Chair of the DVB Commercial Module for UHDTV examines what could follow
Was it raining when Noah built his ark? No. Wise men start ahead of the curve. Both DVB and the EBU are doing so for UHDTV. ‘Disruptive
technology’ like UHDTV takes many years to mature to the point of being ‘on-air’. The ITU UHDTV Recommendation is there, yes. The first Ultra High Definition Television TV sets are already on sale in some countries. But there are still a lot of electrons to flow under the Wheatstone bridge before broadcasting happens. ITU BT.2020 specifies two UHDTV levels, UHD-1 and UHD-2. They are successively four times the spatial resolution of 1080p and 16 times its resolution – 8Mpixels and 32Mpixels. There are other features which will bring higher quality to UHDTV; new colour primaries that will embrace even those in tomorrow’s OLED displays, 10- or 12-bit/sample, and an old wish-list item, ‘constant luminance coding’. The ‘big one’ is the inclusion of a frame rate of 120Hz – twice the highest used today for any media – movie or TV. This should really benefit sports.
At a DVB-EBU fact-finding workshop, we estimated that the initial commercial demand for UHD-1 broadcast services would materialise in 2014/2015. Even by that time, its lesser cousin HDTV will still not be universal. But today the ‘development cycle’ is faster than the ‘implementation cycle’ for new media. So work is now underway in the DVB Project to specify a ‘broadcast profile’, UHD-1. Set makers have clear plans to market UHD-1
‘Coupled with the improved content- adaptive HEVC, this means that UHD-1 will be very broadcastable by satellite, cable or a terrestrial system like DVB-T2’
displays. UHD-2, on the other hand, should wait until there are commercial plans for UHD-2 displays.
It is the conundrum of UHDTV that UHD-2 will come along ‘X’ years after UHD-1,
David Wood: ‘The DVB answer is that we just have to take things as they come, and start with UHD-1.’ Do you agree?
and X may be shorter than the ‘roll out’ cycle for UHD-1. Is it better to go with UHD-1 or wait for UHD-2? What’s a guy to do? The DVB answer is that we just have to take things as they come and start with UHD-1. Do you agree?
The enabler
Coming at the same time as ITU UHDTV Recommendation is the enabler of UHDTV broadcasting – HEVC compression. Perceived quality does not increase linearly with spatial or temporal resolution, rather with their square roots. Happily, compressed bit rate
probably does the same. Coupled with the improved content-adaptive HEVC, this means that UHD-1 will be very broadcastable by satellite, cable, or a terrestrial system like DVB-T2. The broadcasting standard need not constrain the parameters of UHD-1. UHD-1 trials in Korea with DVB-T2 have used bit rates of 20-25Mbps. We also examined whether
there are limitations due to programme production technology. Here again the answer seems to be, at least in principle, no. We are about to enter the age of fibre optic interconnection, which means
that essentially anything we reasonably ask for can be moved about the studio. However, it is not all plain sailing. Although the HEVC specification allows pretty much anything from BT.2020, at the DVB/EBU workshop it seemed that UHD-1 receivers – essentially the ICs – would not be available running at up to 120Hz frame rate by 2014/15. So, the discussion today is about two generations of UHD- 1 receivers. The first, UHD-1C would allow up to 60Hz frame rate, and be available in 2014/15. The second, UHD-1H would be available later in the decade, and allow up to 120Hz. How can the system be arranged so that UHD-1C sets can still watch UHD-1 content at 120Hz when available? An answer may be to broadcast the UHD-1 120Hz signal as a spatially scalable signal with a 1080p/120Hz base layer, and to include in UHD-1C sets the capability to decode
1080p/120Hz. This should be within the capability of the UHD- 1C chip sets.
The discussion today is also about whether to request the ITU to add 100Hz to the UHDTV frame rates, or even 150Hz, as this would allow higher quality and lower cost conversion to and from 25Hz/50Hz HDTV.
The UHD-1C scenario is a practical one to get the show on the road, and movie content will not be troubled by the limitation on frame rate. When available, 120Hz will have serious benefits for critical sports content, but we may have to wait a while. But probably Noah had to be pragmatic too, when he was building the Ark.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124