HD TECHNOLOGY Juan Carlos Rosero
HISTORY • The term high definition once described a series of television systems originating from the late 1930s; however, these systems were only high definition when compared to earlier systems that were based on mechanical systems with as few as 30 lines of resolution.
Great Britain • The British high definition TV service started trials in August 1936 and a regular service in November 1936 using both the (mechanical) Baird 240 line and (electronic) Marconi-EMI 405 line (377i) systems. The Baird system was discontinued in February 1937.
France • In 1938 France followed with their own 441 line system, variants of which were also used by a number of other countries. The US NTSC system joined in 1941. In 1949 France introduced an even higher resolution standard at 819 lines (768i), a system that would be high definition even by today's standards, but it was monochrome only.
Main differences • All of these systems used interlacing and a 4:3 aspect ratio except the 240 line system which was progressive (actually described at the time by the technically correct term 'sequential') and the 405 line system which started as 5:4 and later changed to 4:3. The 405 line system adopted the (at that time) revolutionary idea of interlaced scanning to overcome the flicker problem of the 240 line with its 25 Hz frame rate.
Color TV • Color broadcasts started at similarly higher resolutions, first with the US NTSC color system in 1953, which was compatible with the earlier B&W systems and therefore had the same 525 lines (480i) of resolution. European standards did not follow until the 1960s, when the PAL and SECAM colour systems were added to the monochrome 625 line (576i) broadcasts.
Analog HD Systems (France) • French 819 lines system (768i) was used only on VHF for the first French TV channel. It first started transmission in 1949 and was discontinued in 1985.
Analog HD Systems (URSS) • In 1958, the Soviet Union developed Тransformator (Russian: Трансформатор, Transformer), the first high-resolution (definition) television system capable of producing an image composed of 1,125 lines of resolution aimed at providing teleconferencing for military command. It was a research project and the system was never deployed in the military or broadcasting.
Analog Systems (Japan) • In 1969, the Japanese state broadcaster NHK first developed consumer high-definition television Hi-Vision or MUSE with a 5:3 aspect ratio, a rather wider screen format than the usual 4:3 standard. The system required about twice the bandwidth of the existing NTSC system but provided about four times the resolution (1080i/1125 lines). Satellite test broadcasts started in 1989, with regular testing starting in 1991 and regular broadcasting of BS-9ch commenced on 25 November 1994, which featured commercial and NHK programming.
Analog Systems (USA) • In 1981, the MUSE system was demonstrated for the first time in the United States, using the same 5:3 aspect ratio as the Japanese system. Upon visiting a demonstration of MUSE in Washington, US President Ronald Reagan was most impressed and officially declared it "a matter of national interest" to introduce HDTV to the USA.
Analog Systems (USA) • Several systems were proposed as the new standard for the USA, including the Japanese MUSE system, but all were rejected by the FCC because of their higher bandwidth requirements. At this time, the number of television channels was growing rapidly and bandwidth was already a problem. A new standard had to be more efficient, needing less bandwidth for HDTV than the existing NTSC.
Analog HD Unification • In 1983, the International Telecommunication Union's radio telecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, the world already having split into two camps, 25/50Hz and 30/60Hz, related by reasons of picture stability to the frequency of their main electrical supplies.
Analog HD Unification • The IWP11/6 working party considered many views and through the 1980s served to encourage development in a number of video digital processing areas, not least conversion between the two main frame/field rates using motion vectors, which led to further developments in other areas. While a comprehensive HDTV standard was not in the end established, agreement on the aspect ratio was achieved.
Analog HD Unification • Initially the existing 5:3 aspect ratio had been the main candidate but, due to the influence of widescreen cinema, the aspect ratio 16:9 (1.78) eventually emerged as being a reasonable compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format. The 16:9 ratio was chosen as being the geometric mean of 4:3, Academy ratio, and 2.4:1, the widest cinema format in common use, in order to minimize wasted screen space when displaying content with a variety of aspect ratios.
Analog HD Unification • An aspect ratio of 16:9 was duly agreed at the first meeting of the IWP11/6 working party at the BBC's Research and Development establishment in Kingswood Warren. The resulting ITU-R Recommendation ITU-R BT.709-2 ("Rec. 709") includes the 16:9 aspect ratio, a specified colorimetry, and the scan modes 1080i (1,080 actively interlaced lines of resolution) and 1080p (1,080 progressively scanned lines). The current Freeview HD trials use MBAFF, which contains both progressive and interlaced content in the same encoding.
Analog HD Unification • It also includes the alternative 1440×1152 HDMAC scan format. According to some reports, a mooted 750line (720p) format (720 progressively scanned lines) was viewed by some at the ITU as an enhanced television format rather than a true HDTV format, and so was not included, although 1920×1080i and 1280×720p systems for a range of frame and field rates were defined by several US SMPTE standards.)
Demise of analog HD Systems • This limited standarization of HDTV did not lead to its adoption, principally for technical and economic reasons. NHK's MUSE required over four times the bandwidth of a standard-definition broadcast, and despite efforts made to reduce it to about twice that of SDTV, it was still only distributable by satellite with one channel shared on a daily basis between seven broadcasters. Japan remained the only country with successful public broadcast analog HDTV, starting in 2000 in Japan, and ended in October 2007.
New Standards • Since the formal adoption of Digital Video Broadcasting's (DVB) widescreen HDTV transmission modes in the early 2000s the 525-line NTSC (and PAL-M) systems as well as the European 625-line PAL and SECAM systems are now regarded as standard definition television systems. In Australia, the 625-line digital progressive system (with 576 active lines) is officially recognized as high definition.
Digital Video Broadcasting • DVB is a suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium with more than 270 members, and they are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).
DVB Transmission • DVB systems distribute data using a variety of approaches, including: • satellite: DVB-S, DVB-S2 and DVB-SH • DVB-SMATV for distribution via SMATV • cable: DVB-C, DVB-C2 • terrestrial television: DVB-T, DVB-T2 • digital terrestrial television for handhelds: DVB-H, DVB-SH • microwave: using DTT (DVB-MT), the MMDS (DVB-MC), and/or MVDS standards (DVB-MS)
ATSC Standards • The ATSC standard was developed in the early 1990s by the Grand Alliance, a consortium of electronics and telecommunications companies that assembled to develop a specification for what is now known as HDTV. ATSC formats also include standard-definition formats, although initially only HDTV services were launched in the digital format.
ATSC RANGE • The high definition television standards defined by the ATSC produce wide screen 16:9 images up to 1920×1080 pixels in size — more than six times the display resolution of the earlier standard. However, many different image sizes are also supported.
Rise of digital compression • Both ATSC and DVB were based on the MPEG-2 standard. The DVB-S2 standard is based on the newer and more efficient H.264/MPEG-4 AVC compression standards. Common for all DVB standards is the use of highly efficient modulation techniques for further reducing bandwidth, and foremost for reducing receiver-hardware and antenna requirements.
Digital HD (USA) • HDTV technology was introduced in the United States in the 1990s by the Digital HDTV Grand Alliance. The first public HDTV broadcast in the United States occurred on July 23, 1996. The American Advanced Television Systems Committee (ATSC) HDTV system had its public launch on October 29, 1998, during the live coverage of astronaut John Glenn's return mission to space on board the Space Shuttle Discovery.
Digital HD (Europe) • Although HDTV broadcasts had been demonstrated in Europe since the early 1990s, the first regular broadcasts started on January 1, 2004 when the Belgian company Euro1080 launched the HD1 channel with the traditional Vienna New Year's Concert.
Digital HD (Europe) • These first European HDTV broadcasts used the 1080i format with MPEG-2 compression on a DVB-S signal from SES Astra's 1H satellite at Europe's main DTH Astra 19.2°E position. Euro1080 transmissions later changed to MPEG-4/AVC compression on a DVB-S2 signal in line with subsequent broadcast channels in Europe.
WQHD (1440p) • The Wide Quad High Definition, display standard is a resolution of 2560 x 1440 pixels in a 16:9 aspect ratio. It is four times the resolution of the 720p display standard, hence the name. Their high pixel counts and heavy display hardware requirements mean that there are currently few LCD monitors which have pixel counts at these levels. It is a non-standard resolution found in some displays, such as the Dell UltraSharp U2711 and the 27" iMac.
QFHD (2160p) • Quad Full High Definition) is a non-standard display resolution of 3840 x 2160 pixels arranged in a 16:9 aspect ratio. It is four times the resolution of the 1080p display standard, hence the name. • In early 2008, Samsung revealed a proof-of-concept 82-inch LCD TV set capable of this resolution and LG has demonstrated an 84-inch displayEyevis produces a 56" LCD named EYELCD 56 QHD HD while Toshiba makes the P56QHD, and Sony the SRM-L560, all which can deliver a resolution of 3840 x 2160.
Super Hi-Vision • Super Hi-Vision (also known as 4320p, 8K, Ultra High Definition Television (UHDTV), and Ultra High Definition Video (UHDV)) is an experimental digital video format, currently proposed by NHK of Japan, the BBC, and RAI.
Super Hi-Vision • Sky also appears to be interested in the technology. During IBC 2008 Japan's NHK, Italy's RAI, the BBC, RTE, Sony, Samsung, and Panasonic (with various partners) demonstrated the first ever public live transmission of Super Hi-Vision, from London to the conference site in Amsterdam. • In addition, it was demonstrated at the BBC's Media Centre in West London in early October 2008. The BBC has been looking into the use of its Dirac codec with Super Hi-Vision.