Alan Meckler of Meckler Media and I did 3 large HDTV conference in the late 80s and 1991. About the same time we started publishing together the HDTV World Review , which ran for four years. I did the gathering of the authors and assigned topics. Alan was responsible for physical publishing and mail distribution of the publication. This is just one issue but it is significant in that it shows the evolution of thinking towards what we now have. Without this seminal thinking HDTV would have been derailed along the way. I am constantly impressed with the far reaching vision that many of our authors had. They understood where HDTV was going, though in the early days the technical approach was not on as solid a footing as was the vision to where we would go. _Dale Cripps In This Issue... Digital Spectrum Compatible HDTV Wayne Luplow page 4 Advanced Digital Television Glenn Reitmeier and Carlo Basile Advanced Compatible Television Michael Isnardi et. al. Advanced Television Test Center Update Joel Chaseman HDTV And Movies in Japan Takehisa Ishida HDTV In A Stall -- A Vision Dale E. Cripps Editorial Board Executive Editor: Dale E. Cripps Editor: Bija Gutoff Managing Editor: Doreen Beauregard Editorial Vice President: Anthony Abbott Advertising Director: Marilyn Reed Publisher: Alan M. Meckler Update July 13, 1999 Before there was the Grand Alliance, there were the parts. What follows are several of the parts which later fused into being the Grand Alliance. Dale E. Cripps Digital Spectrum Compatible HDTV Wayne Luplow outlines the HDTV solution developed by Zenith and AT&T, called Digital Spectrum Compatible HDTV. DSC-HDTV is designed to address many of the real-world obstacles of today's U.S. broadcasting environment. Building on a wide acceptance of the basic advantages of digital signal transmission, the Zenith/AT&T system extends the benefits of digital with new featuers. Progressive scanning is a faster form of high resolution scanning that permits close synergy between HDTV and computer technology. Low-power transmitters and special filters allow DSC to eliminate interference both to and from NTSC channels. And compression technology helps DSC squeeze data-heavy digital pictures into a 6 MHz channel. These advances, together with proposed solutions to application issues such as television station upconversion and interconnectivity with computers, make a cogent argument for DSC as a significant advance over today's NTSC system. Advanced Digital Television Glenn Reitmeier and Carlo Basile summarize the Advanced Television Research Consortium's work on Advanced Digital Television, a fully digital system that delivers HDTV in a 6MHz channel. The ATRC has developed new digital compression and transmission techniques, including MPEG++, Prioritized Data Transport format, and Spectrally-Shaped QAM, as key elements in an ADTV system that provides high-quality broadcast digital HDTV service. Building on a foundation of accepted technologies and emerging standards, they also propose ADTV for its economy, reliable service, compatibility with other industries and growth potential. Advanced Compatible Television Another view from the Advanced Television Research Consortium comes from Michael Isnardi and colleagues, who believe that existing NTSC channels should be upgraded even while new HDTV standards are being implemented. ACTV is a single-channel compatible widescreen transmission system that has been submitted as a candidate for the U.S. EDTV standard. With ACTV, broadcasters can take a gradual approach to equipping stations with advanced television systems, thereby gaining enhanced definition, wide aspect ratio and digital audio while remaining compatible with standard 6MHz NTSC channels and existing receivers. Advanced Television Test Center Update Joel Chaseman, a television industry insider for many years, gives a brief progress report on the work of the Advanced Television Test Center, a group made up of broadcast networks and associations together with the Electronics Industry Association. HDTV and Movies In Japan In Japan, HDTV has already been used to make many feature films. NHK's Takehisa Ishida provides a look at HDTV's role in movie system applications, including not only movie making itself but various combinations of film, broadcast and video with distribution via satellite, cable, tape or disk. He describes recent advances in HDTV equipment now available for movie systems, and offers a discussion of practical considerations in making HDTV movies, with synopses of a half-dozen such projects. HDTV In A Stall In light of HDTV's current stall--while testing, standard-setting and other issues remain to be worked out--Dale Cripps suggests the missing ingredient: one driving vision, and a visionary in the tradition of David Sarnoff to embody it. Cripps also proposes a new scenario, global networks, to reflect a new-world coalescence of viewer audiences, broadcasters, manufacturers and program producers. Bija Gutoff Editor Digital Spectrum Compatible HDTV From Zenith/AT&TBy Wayne Luplow The advantages of high-definition television are commonly known--outstanding picture and equally impressive sound. But it is not commonly known how HDTV would overcome obstacles to those advantages in the U.S. terrestrial broadcasting environment. The proponents of a U.S. HDTV standard need to describe how their systems would operate in a real world fraught with picture distortion, interference, cliff effects, channel-change recovery difficulties and complex motion scenes. And they should describe how their HDTV systems could be applied in other media such as cable, computers, fiber, satellite and VCRs. It is this context of real world applications, problems and solutions that reveals the excellence of the Digital Spectrum Compatible HDTV (DSC-HDTV) system from Zenith Electronics Corporation and AT&T. Digital HDTV All but one of the proposed HDTV systems uses a digital rather than an analog format. The advantages of digital signal transmission include pictures of movie theater quality that are free of snow and ghosts that degrade conventional broadcasts. Images possess a lifelike quality heretofore unseen in television broadcasts. That picture quality is accompanied by sound quality that matches a compact disc. Digital transmission also offers potential for easier interfaces and interference-free interaction with other media such as cable, satellite, fiber and computers. Digital Spectrum Compatible HDTV Several advantages of digital transmission technology are extended by specifics of the Zenith/AT&T system. DSC-HDTV uses progressive scanning, for example, which presents complete picture information twice as fast as interlace scanned systems. DSC-HDTV gives a complete picture every sixtieth of a second, twice as fast as interlace scanned systems, which give a complete picture every thirtieth of a second. Given equal time comparisons, the Zenith/AT&T system gives 1,575 lines of resolution in one-thirtieth of a second while proposed interlace systems give 1,125 or 1,050 lines every one-thirtieth of a second. The progressively scanned picture from DSC-HDTV is free of jagged edges and other picture-distorting problems that plague interlace scanned systems. Progressive scanning also gives the Zenith/AT&T system excellent synergy with computer technology, which also uses progressively scanned images. Thus, DSC-HDTV images could be displayed on a computer screen without going through complex processing. Synergy with computer systems also is enhanced by the use of square picture elements, which perform better with computer graphics and in special effect productions. Zenith/AT&T transmission technology eliminates interference. The transmission system uses a low-power transmitter and signal processing steps to avoid interference into NTSC channels. The other side of the equation--preventing NTSC signals from interfering with weak HDTV signals--posed a significant challenge. The solution centers on a unique digital filter in the HDTV receiver and a complementary filter in the HDTV transmitter. As a result of this unique filtering technology, true high-definition television would be available in the same service area as traditional NTSC broadcasts. The system delivers a clear, digital-perfect signal even at the fringes of a reception area. Although some have speculated about sudden loss of picture in a digital environment, no such effect would exist in the Zenith/AT&T system. In other proposed digital systems, a compilation of errors can lead to a “cliff effect, in which a receiver beyond a certain distance from the transmitter suddenly loses the HDTV picture. A viewer at that distance would essentially be without HDTV service. DSC-HDTV, however, would produce clear pictures even at the outer edges of today's typical terrestrial broadcast service area (55 miles from the transmitter). Good quality HDTV pictures with some visible errors would be received up to 70 miles away from the transmitter. DSC-HDTV also would use unique compression technology to squeeze the massive amounts of digital picture information into a 6MHz channel. The system's compression algorithm has several unique features, including motion compensation, which analyzes each television frame at the transmitter to prepare it for transmission; and adaptive quantization, which takes into account the idiosyncrasies of the human visual system to present HDTV pictures without perceptible loss of resolution. Full high-definition resolution is retained even when broadcasting live, rapid-motion sports and similar events. Even temporary loss of resolution when changing channels is minor. Image recovery is crucial, especially when many channels are available. DSC-HDTV would give complete image recovery in a fraction of a second. Recovery in other proposed systems may be far slower. A serious discussion of an HDTV standard for the U.S. market must include not only performance issues, but also issues of application. Broadcaster concerns about start-up costs are consistently raised. But, contrary to common belief, broadcasters will be able to enter the era of high-definition television without replacing all of their studio equipment. With a simple, new “up-conversion process, many television stations won't need to make a costly switch to a full high-definition studio with new cameras, recorders and encoders. By equipping their stations with a Zenith/AT&T Digital Spectrum Compatible simulcast transmitter and antenna, broadcasters would be able to “pass through network television programming. For locally produced programming, they would use the new up-conversion process to broadcast very high quality NTSC images on the digital transmission system. With a minimal investment, television stations would be able to move to high-definition television broadcasts by acquiring simulcast transmission equipment necessary to broadcast a network-fed high-definition signal and the up-converted locally produced program material. Issues of interconnectivity also are crucial to discerning the best HDTV system for the U.S. market. The synergy between DSC-HDTV and the computer environment is clear. Progressive scanning greatly reduces the complexity of processing HDTV information so it can be displayed on a computer workstation. Square pixels perform better with computer graphics and special effect productions. DSC-HDTV also offers opportunities for interoperability, or ease of conversion among different formats, change resolution, frame rates, etc. Interoperability would come into play when HDTV signals are transmitted for communication and computing purposes, stored and interfaced for other uses. The DSC-HDTV limits the amount of processing and storage required for these processes. Extensibility also is an issue that should come into play when discussing HDTV system proposals. The basic extensibility question for any HDTV system is: Is this particular system able to adapt to more advanced technology that is likely to be developed in the future? The Zenith/AT&T system is flexible, allowing it to economically adapt its current standards to higher resolution displays as they are developed. Any winning HDTV system should serve as a building block for future technological advances. An application of extensibility may be, for example, the use of a windowed computer program to display HDTV video within a high resolution image on a computer display. The window could use an image of different resolution from the image shown on the main section of the screen. As extensibility is needed to build on a system's technology, a successful HDTV system would allow for scalability, which allows easy creation of lower resolution pictures from compressed HDTV material. Conclusion Proponents of specific HDTV systems should gain credibility as they explain how their systems would address real world broadcasting problems. These problems, and their solutions as proposed by Zenith and AT&T, indicate the strength of the Digital Spectrum Compatible HDTV system. Obvious benefits of digital HDTV include outstanding picture and sound, easier interface with computer, telephone data and other communications systems, and interference-free signals for cable, satellite, fiber and VCRs. These positives are expanded in the Zenith/AT&T system through employment of progressive scanning to eliminate jagged edges and other picture-distorting problems, and square pixels to perform better with computer graphics and in special effect television productions. Image recovery from channel changes would be in a fraction of a second. Because of unique transmission technology, DSC-HDTV would prevent NTSC and HDTV signals from interfering with one another. Unique compression technology in the DSC-HDTV system includes several features that retain full high-definition resolution even when broadcasting live, rapid-motion sports and similar events. Other significant advantages of the DSC-HDTV include service area equal to today's typical NTSC service area and reasonably priced start-up costs to broadcasters via up-conversion. Finally, the DSC-HDTV system has exceptional interconnectivity characteristics, a feature that is crucial to any system's success. Computer friendliness, interoperability, extensibility and scalability all are strong aspects of the Zenith/AT&T proposal. Individually, any one of these improvements over today's NTSC system would be a significant advance. Combined, they represent a major technological development of the 1990s that should yield fruit well into the twenty-first century. Wayne C. Luplow is Zenith Electronic Corporation's division vice president of research and development for advanced television systems. He heads the company's high-definition television R&D program, leading the Zenith/AT&T technical team developing the Digital Spectrum Compatible HDTV system. In conjunction with his Zenith responsibilities, Luplow is active in industry-wide HDTV activities, including the FCC's Advisory Committee on Advanced Television Services, the Center for Advanced Television Services, and the executive committee of the Advanced Television Systems Committee. A senior member of the Institute of Electrical and Electronics Engineers, Luplow serves as editor of the IEEE's Transactions on Consumer Electronics. He is an elected member of the administrative committee of IEEE's Consumer Electronics Society and has been publication chairman for the committee since 1976. Before joining Zenith, Luplow was employed by RCA at the David Sarnoff Research Laboratories in Princeton, New Jersey. He holds a BSEE from the University of Wisconsin and a MSEE from the University of Pennsylvania. Advanced Digital Television By Glenn Reitmeier and Carlo Basile Introduction The United States faces a significant challenge in establishing an HDTVstandard that can survive the next 50 years. Digital compression and transmission technology represents a revolutionary new approach to the design of television systems, and the opportunity to establish a new standard is well-timed to coincide with the practical application of these technologies. HDTV needs to be flexible and extensible, accommodating new and as yet unforeseen media and applications, now and in the twenty-first century. Over the lifetime of a simulcast HDTV standard, the universality of digital technology will surely lead to novel combinations of applications that are now considered separate, and will enable greater compatibility among different types of consumer electronics, telecommunications, and computing equipment. This challenge--to deliver the best HDTV system for the U.S. that can be built upon in the future--is being met by the Advanced Television Research Consortium (ATRC) in the form of Advanced Digital Television (ADTV). ADTV's strengths are its superior quality image, its robust signal and graceful degradation characteristics, and its important means of providing for future developments. Advanced Digital Television ADTV is a fully digital system that delivers high-definition television in a 6MHz channel (Figure 1). The design of ADTV has been driven by the need of the terrestrial broadcast, cable television, and consumer electronics industries to have an economical HDTV simulcast system that provides robust and reliable service; that can peacefully co-exist with NTSC; and that can be expanded upon and grow in the future. To meet these needs, ADTV has made significant improvements to proven digital compression and transmission techniques, and molded them into a single cohesive system. There are three key elements in the ADTV system: -First, ADTV's video compression, called MPEG++, is based on a special ATRC implementation of the MPEG** (Moving Pictures Expert Group) compression approach. MPEG++ upgrades the standard MPEG approach to HDTV performance level and incorporates a video data prioritization process that identifies the most important video data so that it can be transmitted with the greatest reliability. The MPEG foundation provides compatibility with the computer industry, which results in an economically attractive approach. Further, our MPEG++ extensions provide for reliable service in the terrestrial broadcast environment. -Second, ADTV has a Prioritized Data Transport (PDT) layer. PDT is a cell relay-based data transport format that supports the prioritized delivery of video data, thus providing the feature of graceful service degradation under impaired channel conditions. The cell relay-based format is similar to that of broadband ISDN (Integrated Services Digital Network) and provides for a high degree of interoperability and growth potential. PDT also offers service flexibility, allowing broadcasters to deliver virtually any mixture of video, audio, and auxiliary data, as market opportunities evolve. -Third, ADTV applies spectral-shaping techniques to Quadrature Amplitude Modulation (QAM) to carefully minimize interference from and to any co-channel NTSC signals. The result is an extremely robust data transmission system, known as the Spectrally-Shaped QAM (SS-QAM), that can co-exist with NTSC in the simulcast environment. System Rationale To understand some of the basic elements within ADTV and to fully appreciate their benefits, a discussion of some of the rationale that shaped the ADTV system is in order. A well designed digital HDTV system for terrestrial broadcast should offer significant advantages in performance and flexibility over analog approaches. These advantages manifest themselves in many ways in ADTV. As a first example, although ADTV has been submitted to the ACATS as a 1050-line system, it is designed to provide flexible support of a wide range of services and future media formats. The initial hardware implementation will use the interlaced scan format for video source and display (1050/59.94/2:1), with a 16:9 aspect ratio and more than twice the NTSC resolution. Selection of this initial format was based on current camera and display technologies, and does not preclude a future adoption of other video formats, consistent with the evolution of studio equipment and production standards. Another fundamental advantage of a digital approach is that computationally-based digital approaches allow a video compression system to efficiently and adaptively exploit spatial and temporal redundancies in a picture far better than analog approaches can. Research efforts in video data compression have been ongoing for several years within ATRC laboratories. Figure 2 illustrates the basic concept of motion-compensated video compression. At the encoder, motion vectors are computed to predict the current frame from a previous (and/or following) frame. This process is efficient because only the motion vectors and the difference are transmitted, not the entire frame. A rigorous and comprehensive evaluation of numerous video compression approaches was of primary importance to the design of ADTV. Among different video compression techniques, the MPEG approach represents a collection of well-known, well-proven compression methods that have been filtered from a great deal of image coding research conducted around the world during the past years. For example, Advanced Digital Television's MPEG is unique among the digital HDTV proposals because it uses forward and backward motion compensation resulting in improved picture quality. The picture quality of ATRC's implementation of MPEG was competitive with other ATRC-proprietary techniques. The combination of MPEG's performance and the fact that it already enjoys the benefit of being widely accepted as an emerging international standard caused it to be selected as the basis for ADTV. Digital transmission techniques have the well-known property of being impervious to moderate levels of channel impairment, and avoiding accumulation of noise and other artifacts when passed through a series of transmission relay stages. But MPEG, like any video compression, is vulnerable to hostile transmission conditions. To combat the disruptive nature of transmission errors on the video data stream, a channel-specific video prioritization layer was designed into the ADTV compression algorithm. We use the name MPEG++ to indicate that MPEG has been adapted and improved to meet the requirements of the terrestrial broadcast environment. Coupled with prioritized data delivery, MPEG++ represents an extremely robust video compression approach. The unique requirements of simulcast transmission demand special attention to the delivery and transport of the compressed video information. This motivated an ATRC research effort to design a transport format to provide extremely reliable delivery of the ADTV service to viewers. The result of this “channel-ruggedization effort is the “fast packet cell transport format. Cell-relay transport format refers to a data communication format in which information bits are carried in cells consisting of fixed-size data, header, and trailer fields (Figure 3). Because of the relative ease of handling a fixed-size cell, even at high-speed, most high-speed data communication networks have adopted a fixed-size cell relay format. A well-known example of a cell-relay transport format is the ATM (asynchronous transfer mode) protocol in broadband ISDN. ADTV's cell transport format ensures a high degree of robustness of the signal. As reception worsens in fringe areas, for example, packet loss occurs. Other digital systems may take an entire frame time to recover from a packet loss. ADTV's PDT allows resynchronization of the video data to occur during the next cell. This is made possible by putting recovery information in each cell's header. With its link-level asynchronous time division multiplexing features, ADTV offers the advantage of flexible multiplexing of video, audio, and data with bit-rates that do not need to be specified in advance. This is made possible since each cell specifies its own service type (e.g., identifying video, audio 1, audio 2, auxiliary data, etc.) and any combination of cells is allowed! Perhaps the most difficult part of a digital HDTV system is its RF transmission approach. Once the data have been compressed by the source coder, they must be “packaged and transmitted over the hostile terrestrial broadcast channels. It is a mandatory design consideration that any new HDTV service be NTSC co-channel compatible in order to allow the new HDTV signal to be broadcast without requiring additional transmission spectrum. Currently-defined “taboo channels are available in the sense that there are presently no signals that are transmitted at these taboo frequencies. These channels are taboo, however, because a typical NTSC broadcast signal transmitted at these frequencies would interfere with and be interfered by the broadcasts in existence today. This situation poses additional design requirements to include a transmission technique that will be robust in an NTSC co-channel and taboo-channel environment. ADTV addresses these low interference requirements in two directions. First, minimal interference from the new HDTV signal into NTSC (so as not to disrupt existing NTSC services) is achieved with lower power for the ADTV signal. Second, minimal interference from NTSC into the HDTV signal (so that a high-quality HDTV service can be provided) is achieved by an ADTV signal that is relatively immune to NTSC interference and noise. Summary ADTV is a practical solution that meets the challenges of the digital simulcast environment. The efficient MPEG++ compression, the Prioritized Data Transport format, and the Spectrally-Shaped QAM have been melded into a powerful system approach for digital simulcast of HDTV. The successful integration of these three key system layers means that ADTV will provide robust high-quality broadcast digital HDTV service to the American public. Economy, reliable service, compatibility with other industries, and growth potential are four significant benefits derived from ADTV. ADTV is a proposal that is built upon a solid foundation of widely accepted technologies and important emerging standards. This approach will lead to rapid industry acceptance, but perhaps even more importantly, it will establish an important common technology base across many business sectors vital to successful development of a globally-competitive HDTV industry in the United States. Glenn Reitmeier is director of the High-Definition Imaging and Computing Laboratory at the David Sarnoff Research Center in Princeton, New Jersey, where he is responsible for computing research and digital high-definition television activities. He joined RCA Laboratories at the David Sarnoff Research Center in 1977, the same year he received a BSEE summa cum laude from Villanova University. He also holds a master's degree in systems engineering from the University of Pennsylvania. Reitmeier's professional expertise is in the fields of digital television, image processing, and computing. Carlo Basile is head of the Advanced Television Systems department at Philips Laboratories, North American Philips Corporation in Briarcliff Manor, New York. He joined the staff of Philips Laboratories in 1983 and has been involved in the development of various advanced television systems for terrestrial, cable, and satellite broadcasting. He holds a BSEE and a MSEE from the Polytechnic Institute of New York. The authors wish to express their thanks to Cynthia S. Gray for her help in the preparation of this article. The Advanced Television Research Consortium is comprised of the David Sarnoff Research Center, Thomson Consumer Electronics, Inc., NBC, and Philips Consumer Electronics Company. Advanced Compatible Television By Michael Isnardi, C.B. Dieterich, T.R. Smith, R.N. Hunt and J.L. Koslov Introduction While the implementation of HDTV will mean simulcasting new channels with new amenities, current NTSC channels will remain in place for many years. Concurrent with the establishment of this new standard of quality for HDTV should be an upgrade of those existing channels, maximizing the full benefits of NTSC and providing a higher level of performance. Advanced Compatible Television (ACTV) will improve NTSC to its fullest advantage to benefit consumers, broadcasters, cable operators, and satellite service providers. Advanced Compatible Television is a single-channel compatible widescreen transmission system submitted for testing as a candidate EDTV standard for the United States. It provides broadcasters a degree of flexibility in equipping stations for an advanced television system by allowing a gradual approach to a full or partial upgrade. A move to implement ACTV would also serve as an impetus to commence full-fledged widescreen production. Advanced Compatible Television ACTV offers enhanced definition, wide aspect ratio, and digital audio while fitting compatibly within a standard 6MHz NTSC channel. ACTV is compatible with all existing NTSC receivers. When ACTV is transmitted, NTSC receivers will display a normal (4x3) aspect ratio, NTSC-quality picture virtually indistinguishable from their present performance; ACTV receivers will display a 16x9 aspect ratio image, a horizontal resolution improvement over NTSC, and progressive scanning. ACTV is consistent with display technologies anticipated for the future, and it can be delivered without new channel allocations. ACTV has undergone continual improvement over the past five years to provide a 16x9 widescreen picture with enhanced resolution, reduced NTSC artifacts, and digital audio. ACTV offers broadcasters a rapid, affordable way to deliver widescreen programming without losing their current audience share and without finding additional broadcast spectrum. Because of its affordability and ease of implementation, ACTV can serve as a catalyst for HDTV by building a population of widescreen programs and receivers. Even in a future HDTV simulcast environment, broadcasters will have the option to preserve the value of their NTSC channel by upgrading to ACTV. Each broadcaster can select the right system or combination of systems to meet that challenge from competing widescreen media. System Rationale The ACTV video signal is fully compatible when decoded by existing NTSC receivers. The transmitted ACTV signal consists of a main signal plus an auxiliary horizontal detail signal sent in RF quadrature. The main signal contains the NTSC encoded 4x3 center panel plus additional side panel information. Existing NTSC receivers decode the main signal as a normal color picture; the side panel and auxiliary signals are physically or perceptually hidden from view. All signals are recovered by an ACTV receiver to reconstruct a widescreen EDTV image with CD-quality sound. Also included are improved immunity to channel noise, ghost cancelling technology, and a channel equalizer that works in tandem with the ghost canceller to correct distortions in the transmitted signal. The ACTV encoder accepts a widescreen source image and produces an “NTSC-like version of the 4x3 center panel at its output. Side panel information, extra horizontal luma detail and digital audio are encoded and transmitted in such a manner as to be transparent to NTSC-compatible receivers. The ACTV decoder, tuned to the same channel as the NTSC-compatible receiver, recovers the side panels, extra horizontal luma detail, and digital audio to produce a noticeably improved widescreen image with CD-quality sound. Figures 1 and 2 show high-level block diagrams of the ACTV system and ACTV components as presented to the Advanced Television Test Center in July, 1991. The ACTV encoder has the following major features: Video Encoder Features: -The Encoder Pre-Processor converts the 525-line progressive scan (525/1:1) YIQ inputs to 525-line interlace (525/2:1) format after appropriate filtering and subsampling in th vertical-temporal (V-T) domain. All interlaced signals are horizontally bandlimited, and the luma highs and chr