The radio spectrum is sliced for use by a multitude of services and the VHF/UHF band assigned to terrestrial television broadcasting is very narrow. Spectrum scarcity used to make television a great business to be in, first because the number of broadcasters in any given market is reduced to a handful of Service Providers (SP), and second because the business has been given the means to sustain itself: public broadcasters by imposing the payment of a licence fee to citizens owning a receiver and commercial broadcasters by relying on advertisements as a source of revenues. Some countries even have the best (so to speak) of both worlds: public broadcasters not only charge licence fees, but they can also get further revenues from advertisement.
That easy life began to change in the 1980s when some SPs, fancying what at that time looked like a virtually infinite bandwidth, started using satellite for television broadcasting. All of a sudden the number of simultaneous programs, until that time reduced, could easily grow by orders of magnitude. Practically, however, those who wanted to watch satellite TV had to put up with annoying disruptions in their homes and make substantial expenses in antennas, wirings and STBs. Not really a deterrent, but the viscosity of habits established in decades of TV viewing works wonders.
If there were some relaxed faces in broadcasting companies, there were also concerned people who understood that digital television was still years away, but one day it would come and that day the wind of change would blow like a hurricane. On that day the number of television programs that could be broadcast on the terrestrial network would become, say, 5 times as many. Great news, you would say. Not really, they said – and I say.
The business of a broadcaster is fine tuned to provide its audience programs, either self-produced or acquired, with a degree of attractiveness (somehow related to cost) such that the audience is sufficiently high and characterised to entice advertisers and provide revenues to offset the cost of operation and program production or purchase. Leaving some positive margin is, of course, more than desirable, a necessity. But if one day digital Fairy Morgana suddenly multiplies the number of channels by a factor of 5, are the revenues going to multiply by 5? This is not likely, and this is true for both public and commercial broadcasters. On the cost front, network managers will have to manage 5 times the transmission capacity, but the operation cost of the physical infrastructure will hopefully be multiplied by less than 5. On the other hand, program production and purchase costs are probably going to have something near to a 5-fold increase, if the level of program quality remains the same. The conclusion is that finding a satisfactory new equilibrium point in multichannel terrestrial television may not be straightforward. Ways could be found to manage the transition, but not if the total numer of programs is multiplied by 5, but by a smaller number. This, however, would mean to return unused channel to the state (so called digital dividend), a prospect most broadcaster would balk at.
Some people are more forward-looking than others. Instead of mourning the eventual demise of their business, NHK engineers set out to develop a new television system, which they called HDTV, with a bandwidth 5 times standard television’s. In doing this they were simply continuing the excellent tradition of broadcast engineering, which had begun with the introduction of colour, to extend the capabilities of television.
The model set by NHK, CCIR wrangling notwithstanding, found other converts. The MAC solution pursued by Europe was clearly less bold than Japanese HDTV, but HD-MAC looked like a solution that combined the best of both worlds: an evolutionary path that targeted the eventual goal of HDTV while providing an immediate, compatible improvement to today’s television.
A similar pattern of goal setting drove the American broadcasters but with a very different outcome. A move by the FCC to hand the 700 MHz band allocated to television broadcasting over to cellular telephony, triggered the request by the broadcasting industry to upgrade the general USA broadcasting technology field. By requesting an evolutionary path to HDTV, that industry not only secured the preservation of the existing frequency allocation status, but succeeded in putting an option on yet another portion of spectrum, the one used for the differential signal designed to provide HDTV.
Given the background, one can understand how the worldwide broadcasting industry must have watched with trepidation what was being done by this uncontrolled group of technologists gathered under the name of MPEG (and I would indeed subscribe to the word “uncontrolled”, if I think of some of the active figures in that group, some deeds of one of which I have already told) to provide a digital television broadcasting standard. But, as much as the blue-suit people from IBM made a deal with that group of long-haired programmers working for what would become the Microsoft that we know, so the worldwide broadcasting industry sort of “made a deal” with the uncontrolled MPEG technologists. As an aside, it is worth remembering that, much as in the case of the IBM-Microsoft deal referred to above, the deal that MPEG “signed” was non-exclusive to broadcasting.
Ronald Bedford, then with the Independent Television Association in the UK, Taiji Nishizawa, then Director of the NHK Science and Technology Research Laboratories and Chairman of CCIR SG 11/B, and Robert Hopkins, then the Executive Director of ATSC, attended all the critical meetings in which the MPEG-2 features took shape. They did not so much attend the Video group where the “uncontrolled” ruled, as the Requirements group that set the guidelines for the development of the technology.
Much as the blue-suit people from IBM did not question the low-level DOS function calls that the long-haired Microsoft employees of those early years were defining, so these gentlemen from the worldwide broadcasting industry did not question the prediction modes or packet field choices that the MPEG technologists were making in the red-hot Video and Systems meetings (but the experts from their compnies probably did). Eventually the MPEG-2 standard provided all the functionalities that this industry requested – by no means in a homogeneous fashion – and at no detriment for the functionalities that other industries demanded.
The US ATV project was probably the first MPEG-2 customer through its involvement in the process starting from the time of the Tarrytown meeting. At the end of 1996, the FCC selected part 1 (Systems) and part 2 (Video) and Dolby AC-3 for Audio for use in digital broadcasting of HDTV on the USA terrestrial network to be carried by the 8-VSB modulation system. A few other countries such as Canada, Korea and Taiwan have adopted the same system. Interestingly, the standard does not mandate any display format and indeed there are broadcasters transmitting in interlaced and others in progressive format.
The second customer came from an unexpected quarter. In the USA, where analogue satellite broadcasting had not taken hold at all, Hughes Electronics was aggressively working on a major digital satellite broadcasting project called DirecTV, later to become a separate company with that name. For this initiative the MPEG-2 compression, far from a curse, was a blessing because it lowered the cost of developing the digital technology, enabling a wider offering of programs than could ever have been possible before because of spectrum scarcity and hence service cost. Against all odds DirecTV turned out to be a significant success.
The third customer came from an even more unexpected quarter. In spite of the technical success of European HDTV in the form of HD-MAC, as demonstrated at the winter Olympics in 1992 in Grenoble, Europe started having second thoughts about digital television. At the initiative of Peter Kahl of the German Federal Ministry of Posts and Telecommunication, interested parties started gathering in 1991 as the “European Launching Group” of a “European Project on Digital Broadcasting”. The first talks were directed at creating the European equivalent of the American ATV initiative, obviously skipping the analogue prelude. A technical group within the project started mulling ideas about solutions that employed scalable video coding ideas. However, the results, as with scalable solutions already tried in MPEG, were not up to expectations and the plans for a scalable road to digital television were shelved.
In 1993 the European Project on Digital Broadcasting abruptly decided to redirect its interests to a new direction, viz. digital satellite broadcasting. The political environment, which until that time had been dithering while the project was drafting its charter, finally decided to endorse it. The initiative, under the new name of Digital Video Broadcasting (DVB), was then formally kicked off.
At the top of the hierarchy there was a Steering Board (SB), a body with a limited number of elected members representing European PTT Administrations and industrial members, not necessarily European. Below it there were four committees, the Commercial Module (CM), the Technical Module (TM), the IPR Modulw and the Promotion and Communication Module. DVB takes pride in being “market driven” and therefore the TM does not (or should not) undertake technical work before the CM considers it from the market viewpoint and formally communicates its support. Technical specifications that are produced by the TM are then submitted to the SB for approval, sent to the Comité Européen des Normes (CEN), the European counterpart of ISO; CENELEC, the European counterpart of IEC; and ETSI, the European counterpart of ITU, where appropriate, for rubberstamp and published as European Norms (EN).
In a rather short time, DVB produced the first specification of a complete digital satellite broadcasting system. The audio and video source coding were MPEG-2 Audio and Video, multiplexing and transport were provided by MPEG-2 Systems. The technology specifically developed by DVB was the QPSK modulation scheme for satellite broadcasting. Continuing along this line, DVB later produced modulation standards for CATV (64 QAM) and terrestrial television (COFDM). Other standards developed subsequently concern return channels for different media, Service Information (SI), a description of which programs are available where and when and the Multimedia Home Platform (MHP). So DVB became another major “customer” for the MPEG-2 standard and the first to adopt the full Audio-Video-Systems triad.
The fourth MPEG-2 customer was the DVD. In 1994, a number of CE manufacturers and Hollywood studios led by Toshiba and Warner Bros. defined a new CD format, quickly overcoming a competing format by Sony and Philips. The new format could pack more bits than CD Audio by using shorter laser wavelength, finer track pitch and inter-pit pitch, by gluing two discs back-to-back and by allowing the disc to be played at variable speed. A two-hour movie could be stored on one of these discs in MPEG-2 Program Stream where the video part is encoded at variable speed.
Bits on a DVD may be encrypted. This was the result of protracted discussions between the technology and content companies. The former companies wished to develop a format like CD Audio in which bits are clear-text while the latter were too wary of providing their bits in a form that would lend itself to easy copy and distribution when moved to an IT environment.
The fifth MPEG-2 customer was the Japanese broadcasting industry. One should have expected that, with their investments in analogue HDTV, the land of the rising sun would see anything digital applied to TV as anathema. Not that the development of MPEG-2 should have pleased the bureaucrats at the Ministry of Post and Telecommunication (MPT), but the NHK Science and Technology Center, with a remarkable foresight, were working on a thoroughly conceived digital broadcasting system called Integrated Services Digital Broadcasting (ISDB).
Today MPEG-2 is in universal use in Japan with digital satellite broadcasting in SDTV and HDTV, CATV and Digital Terrestrial Television. Japan is probably the only place where the audio component of television is encoded using MPEG-2 AAC.
MPEG-2 is a recognised success and, because of it, the audio-visual landscape has completely changed. Billions of satellite, cable and terrestrial STBs, and DVD players – hardware or software – have been sold.