EBU Technical Review : No. 276 (Summer 1998)
HDTV or not?
Digital terrestrial TV is about to start in Europe and in the USA, but there is a major split in philosophy between the two regions. Although there are technical differences between the two transmission standards (ATSC and DVB-T), the fundamental distinction is how the broadcasters intend to use the additional capacity offered by digital transmission. In the USA, HDTV is the primary impetus for digital terrestrial TV. Yet in Europe, HDTV has been firmly dismissed as a non-starter. Is Europe wrong? Is North America wrong?
Broadcasters in the USA are keen on HDTV. Why? The straightforward reason is that many consider HDTV to be the future of TV – just as colour TV has replaced black-and-white TV. They might also have been influenced by demands from non-broadcasters for access to the large amount of unused spectrum within the UHF broadcasting band. In the absence of plans by the broadcasters to introduce HDTV, the FCC could well have sold most of this spectrum to mobile radio users. Whatever their reasons, broadcasters in the USA are now making major commitments to HDTV.
No broadcaster in Europe has expressed any real interest in HDTV. Many broadcasters have made HDTV programmes on an experimental basis – some with outstanding success. Some broadcasters are considering using HD production for a limited number of prestige programmes with a long shelf life, but there are no plans to deliver anything other than SDTV (625-line TV) to the public in Europe.
Opinion in Europe is solidly in favour of using the digital capacity for more programmes, rather than for higher quality pictures. In North America, there is arguably little need for additional TV services, given the plethora readily available on cable systems or via analogue or digital satellites. Broadcasters in Europe are reluctant to embrace HDTV because they do not perceive any demand from the public for improved picture quality.
Given the apparently positive attitudes to HDTV amongst North American consumers, is it really true that European consumers are not interested in HDTV? When members of the public have seen demonstrations of HDTV pictures, they are almost universally impressed. However, if you ask individuals to explain why they like HDTV, their first unprompted response is often that they like the shape of the picture (16:9). Why go to the trouble and expense of HDTV if you can get much of the benefit from wide-screen SDTV?
Picture quality is not an issue for most European consumers. In my view, 625-line SDTV signals are well matched to the requirements of most viewers, who typically watch their television sets from a distance greater than 6 times the picture height (6H). Indeed, most Europeans happily watch VHS recordings – which, in technical terms, are desperately inferior to off-air reception of 625-line TV services. Apart from nit-picking engineers, most members of the public remain blissfully unaware of the huge degradation in quality between the original and the recorded versions. It may also be relevant that there was little interest in S-VHS equipment, which offered higher quality albeit at a substantial premium. I understand that S-VHS was attractive in the camcorder market, not because it offered intrinsically higher quality, but because it offered better multi-generation performance.
I suggest that the jump in subjective quality from VHS to SDTV is equivalent to that from SDTV to HDTV. If few people can spot the difference between VHS and SDTV, why would people pay good money for HDTV?
Most work on HDTV has been based on the assumption of viewing distances of about 3 times picture height (3H). At greater viewing distances, HDTV is barely necessary. Having seen numerous side-by-side comparisons of SDTV and HDTV signals being displayed on 28" wide-screen sets, I am not convinced that HDTV is needed until much larger screens become the norm. Even then, I wonder whether technical tricks at the receiver, such as line-doubling and conversion to progressive scanning, might eliminate much of the benefit offered by the full transition to HDTV.
Nevertheless, there is compelling evidence about the current popularity of large TV sets (i.e. 40-55") in North America – despite the vagaries of reception inherent in the 525-line NTSC system. Inevitably, the use of very large screens draws the attention of consumers to such deficiencies. This is likely to act as the catalyst for the move to HDTV.
No similar force is apparent in Europe. Although Europeans are buying an increasing number of TV sets with larger screens (e.g. 26-28"), such sets are not large by North American standards. The market pull for HDTV will be the arrival in the consumer market of large flat panel displays at affordable prices. When 50" flat panels are available, the quality of the pictures from SDTV sources will be inadequate and HDTV will become essential. When will this happen? Not this year. Not next year. Probably, in 7-10 years.
The focus on HDTV in the ATSC standard for digital terrestrial TV, coupled with the lack of interest in HDTV in Europe, has caused some people to assume that the DVB-T system is not capable of delivering HDTV. This is incorrect. All of the DVB standards (satellite, cable, terrestrial, MMDS, SMATV, etc.) can deliver HDTV signals. DVB standards are future proof – even if the Europeans are not yet ready for HDTV, the DVB systems are "HDTV ready". It is worth noting that, after a detailed series of comparative laboratory tests and field trials of the ATSC and DVB-T systems, Australian broadcasters have recently announced that they will introduce HDTV in 2001 using the DVB-T system.
Europe is clearly out of step, not just with the USA, but also with Canada, Japan and Australia – all of which have announced plans for the introduction of digital HDTV. If HDTV is a major success elsewhere, Europe will inevitably follow.
On this occasion, there may be an advantage in not being first in the field. The biggest stumbling block to the success of HDTV is likely to be the cost of HDTV receivers. By making a late transition to HDTV, European consumers will benefit from cost reductions elsewhere and, thus, may be able to avoid very high prices at the start of HDTV.
I apologise that this issue of the Technical Review is late going to press – mainly because effort had to be diverted to the publication of the Final Report of the EBU/SMPTE Task Force for Harmonized Standards for the Exchange of Programme Material as Bitstreams. This Report is being distributed with this issue of the Technical Review.
In the early 1980s, the first EBU/SMPTE Task Force defined the serial and parallel interfaces for digital component video, subsequently adopted by the CCIR (now ITU-R) as Recommendations 601 and 656 – and now universally used for interconnection of digital production equipment. The latest EBU/SMPTE Task Force promises to be even more important. I believe that, within 5 years, almost all new production equipment will be based on the concepts described in their Final Report.
I would like to take this opportunity of publicly thanking all those people who helped the EBU/SMPTE Task Force during the last 2 years, especially the two co-Chairmen – Merrill Weiss and Horst Schachlbauer – for their unfailing wisdom and inspired leadership. I must also acknowledge the Herculean efforts of Mike Meyer and Roger Miles in preparing the Final Report for publication in time for IBC `98 in Amsterdam.
Philip Laven
Director
EBU Technical Department
European Broadcasting
Union 