Glass

This property can be seen in the University of Queensland's pitch drop experiment, where each drop has taken approximately 10 years to fall into the beaker. Recording at 100 Mbits/s, it uses a better color compression method to give better color representation than a standard DV25 or MiniDV cassette and less compression artifacts. Note that pitch, another seemingly-solid material, is in fact a highly viscous liquid, 100 billion times as viscous as water. Broadcast-level HD cameras often record to hard-drives via a raw input/output or to tape or flash disks in formats that support higher bitrates than MiniDV cassettes such a DVCPro HD. Occasionally such glass has been found thinner side down, as would be caused by carelessness at the time of installation. All major Camcorder vendors provide camcorders in this segment. When actually installed in a window frame, the glass would be placed thicker side down for the sake of stability and visual sparkle. It records MPEG-2TS compressed HDTV video on standard DV media (DV or MiniDV cassette tape) and transfers it using Firewire.

The pieces were not, however, absolutely flat; the edges of the disk would be thicker because of centripetal forces. The standard for consumer/prosumer HDTV acquisition is High-Definition Video (HDV). This plate was then cut to fit a window. Some DVD manufacturers such as Philips are licensing the DivX codec in order to play 720p/1080i content recorded on standard consumer DVD-R discs. The likely source of this belief is that when panes of glass were commonly made by glassblowers, the technique that was used was to spin molten glass so as to create a round, mostly flat and even plate (the Crown glass process, described above). This upconversion process can improve the perceived picture quality of standard-definition video. It is then assumed that the glass was once uniform, but has flowed to its new shape. These players, however, are not considered to be true HD DVD players since they include only an integrated scaler to upconvert the standard-definition DVD video to high-definition video.

Supporting evidence that is often offered is that old windows are often thicker at the bottom than at the top. There are now some DVD players that will output enhanced or high-definition signals from standard-definition DVDs. One common misconception is that glass is a super-cooled liquid of practically infinite viscosity when at room temperature. Although they disagree about physical format technology, both the HD DVD and Blu-ray factions have selected the same three video codecs to be mandatory in their designs: specifically, MPEG-2 Part 2, VC-1, and H.264. See also Window. The Blu-ray format has already gained a majority support from almost every major movie studio in the USA, while the HD DVD format has received support from a smaller consortium of companies, many of whom have also pledged support for Blu-ray anyway. These glass types can be further utilised by the following processes:. A more likely possibility is that the PlayStation 3 console (manufactured by Sony, the main advocate of Blu-ray discs) will gain a major lead in sales for Blu-ray players when it launches in 2006.

Several methods of producing glass for applications have been developed, including:. A possible outcome of a messy format war could be the emergence of combo players, as the physical disc sizes are identical. Foamed glass, made from waste glass, can be used as lightweight, closed-cell insulation. As a result, this will likely lead to certain films becoming available only on one format. Glass fibre insulation is common in roofs and walls. Both sides of the HD disc camp are likely to leverage studio partners against each other through exclusive arrangements. Glass in buildings can be of a safety type, including wired, toughened and laminated glasses. A format war is now very likely between the DVD Forum's HD DVD (formerly "Advanced Optical Disc") standard and the Blu-ray Disc Association's Blu-ray disc standard.

Typical uses for glass in buildings include as a transparent material for windows in the building envelope, as internal glazed partitions and as architectural features. Recently, the DVD Forum and the Blu-ray Disc Association failed to agree on standards for high-definition 12-cm discs. Glass has been used in buildings since the 11th century. It was unclear to On2 and the arbitrator whether the Chinese government ever approved the EVD proposal as a standard. Main articles: Architectural Glass and Glazing. On2 filed multiple breach of contract claims for arbitration, but in March of 2005 the arbitrator ruled that E-World had not broken the contract and owed nothing to On2. Stained glass is an art form with a long history; many churches have beautiful stained-glass windows. Soon after the announcement that VP6 would be used on EVD, negotiations between On2 and E-World (the consortium pushing EVD to become a standard) broke down.

See the Harvard Museum of Natural History's page on the exhibit for further information. studio will commit to movies in this format without some form of copy-protection, which is not yet specified. The Blaschka Glass Flowers are still an inspiration to glassblowers today. It is unlikely any major U.S. These were lampworked by Leopold Blaschka and his son Rudolph, who never revealed the method he used to make them. Very few titles were made available in any market for this format, although it is presumed that many would be needed to drive purchase of incompatible players. The Harvard Museum of Natural History has a collection of extremely detailed models of flowers made of painted glass. A low cost for the codec itself is not a significant advantage over DVD, however, as the standalone hardware players will be incompatible with standard DVD-Video unless the manufacturer pays the royalties for the technologies necessary to make the player DVD-compatible.

A significant exception is the collection of pieces by the Blaschkas. As China starts to dominate manufacturing of TV and DVD units, the country's choice of standards becomes more important for everyone. Colored glass is often used, and sometimes the glass is painted, although many glassblowers consider this crude. As an advantage, VP6 would not require royalties on recorded media (although royalties would be charged for player devices at a similar cost as for other codecs). Objects made out of glass include vessels (bowls, vases, and other containers), paperweights, marbles, beads, smoking pipes, bongs, and sculptures. As reported, this was a result of China's desire to avoid royalties on WM9 or AVC. Glass can also be cut with a diamond saw, and polished to give gleaming facets. VP6 was reported by On2 to have been chosen by China for use in the Enhanced Versatile Disc (EVD) format initiative.

Glass that is manipulated in a kiln is called warm glass, and traditional stained glass work is commonly called cold glass work. H.264 is also used by some for encoding video podcasts. Someone who works with hot glass is called a glassblower or lampworker, and these techniques are how most fine glassware is created. Since many movie trailers are released in QuickTime format, when movie distributors started releasing HD trailers on the web the format they chose was H.264. There are many techniques for creating fine glass art; each is suitable for certain kinds of object and unsuitable for others. H.264 has made significant progress towards becoming a widespread video format on the internet thanks to Apple Computer's QuickTime software supporting the format as of version 7. The term "crystal glass", derived from rock crystal, has come to denote high-grade colourless glass, often containing lead, and is sometimes applied to any fine hand-blown glass. Example of broadcasters concerns.

Some artists in glass include Lino Tagliapietra, Sidney Waugh, Rene Lalique, Dale Chihuly, and Louis Comfort Tiffany, who were responsible for extraordinary glass objects. However, this is currently a rumour and has not yet been challenged. Even with the availability of common glassware, hand blown or lampworked glassware remains popular for its artistry. In fact, there is some concern in the community that Microsoft may have appropriated itself the H.264 standard, modified and improved upon it and are trying to resell the solution as VC-1, without providing dues to the MPEG-LA. Volcanic glasses, such as obsidian, have long been used to make stone tools, and flint knapping techniques can easily be adapted to mass-produced glass. The main areas of dominance of VC-1 seem currently to be in the Blu-Ray DVD (HD DVD have not yet announced support for VC-1) and, for obvious reason, the home PCs. Most such glass is mass-produced using various industrial processes, but most large laboratories need so much custom glassware that they keep a glassblower on staff. It has been thought for a while that VC-1 was better adapted for the IPTV world than H.264, but press announcements have also already been made by some of the largest STB manufacturers like Amino, Pace, Kreatel demonstrating solutions based on H.264 standards.

For the most demanding applications, quartz glass is used, although it is very difficult to work. So far, only a handful of very minor broadcasters are seriously considering VC-1. For these applications, borosilicate glass (such as Pyrex) is usually used for its strength and low coefficient of thermal expansion, which gives greater resistance to thermal shock and allows for greater accuracy in laboratory measurements when heating and cooling experiments. H.264 was chosen for several reasons: The standard was validated as an open standard at least a year before VC-1 was seriously considered as a potential open standard, and, then, there is a lot of uncertainty on the levies Microsoft may want to impose once the algorithm is adopted. In laboratories doing research in chemistry, biology, physics and many other fields, flasks, test tubes, lenses and other laboratory equipment are often made of glass. H.264 as a standard has already been selected and adopted by the biggest broadcasters in the USA (DirecTV, DISH Network) and Europe (BSkyB, Premiere, Canal+, TPS, ...). Drinking glasses, bowls, and bottles are often made of glass, as are light bulbs, mirrors, the picture tubes of computer monitors and televisions, and windows. Other codecs are in contention such as AVC (MPEG-4 part 10, also known as H.264, approved by the ITU-T and MPEG standards bodies in early-2003) and the VP6 and now VP7 codecs from On2 Technologies.

Many household objects are made of glass. The codec has been submitted to SMPTE and is in SMPTE's standardization process with an intent for it to become an official SMPTE standard known as VC-1 in the near-future. Since glass is strong and unreactive, it is a very useful material. As of the start of 2005, Microsoft recommends a 3.0 GHz processor with 512 MB of RAM and a 128-MB video card for 1080p playback on Windows XP, though they are now commercially available DVD players, like the KiSS DP-600, that will play back WMV HD DVD ROMs in high definition on HDTV sets. See also: Broad sheet, Blown plate, Polished plate, Cylinder blown sheet, Machine drawn cylinder sheet. Since then, more titles have become available in this format, such as the acclaimed surf documentary Step Into Liquid. This reduced manufacturing costs and, combined with a wider use of coloured glass, led to cheap popular glassware in the 1930s, which later became known as Depression glass. As of November 2003, this format required a significant amount of processing power to encode and decode and the only commercially-available movie that used the codec was the Terminator 2: Extreme Edition DVD (see 1).

In the 1920s a new mould-etch process was invented, in which art was etched directly into the mould, so that each cast piece emerged from the mold with the image already on the surface of the glass. It remains to be seen if the codec will be adopted for widespread use, if only as a Wi-Fi industry standard. Traditionally this was done by a trained artisan after the glass was blown or cast. Microsoft is marketing its high-definition Windows Media 9 Series codec as WMV HD. Art is sometimes etched into glass via acid or other caustic substance (causing the image to be eaten into the glass). In an attempt to provide a bitrate-compatible high-definition format for high-definition video on standard DVD-ROMs, Microsoft introduced their Windows Media 9 Series codec with the ability to compress a high-definition bitstream into the same space as a conventional NTSC bitstream (approximately 5 to 9 megabits per second for 720p and higher). Blenko in the 1920s. It is expected to have a big impact on the HDTV market.

The cylinder method of creating flat glass was first used in the United States of America by William J. Sony will include a Blu-ray player in PlayStation 3, and it will be released during 2006. The invention of the glass pressing machine in 1827 allowed the mass production of inexpensive glass articles. Blu-ray uses a blue-laser optical disc with an MPEG-2 or MPEG-4 codec. Around 1688, a process for casting glass was developed, which led to its becoming a much more commonly used material. Blu-ray technology is currently available only in Japan with a Japanese satellite/terrestrial tuner, but is expected to be released in other world markets in 2006. Venetian glass was highly prized between the 10th and 14th centuries as they managed to keep the process secret. HD programming may be recorded on optical disc using Blu-ray or on HD DVD.

The disk would then be cut into panes. D-Theater is currently a small niche market even within the niche HDTV community, and it appears as if the final D-Theater title was published in 2004. In this process, the glassblower would spin around 9 lb (4 kg) of molten glass at the end of a rod until it flattened into a disk approximately 5 ft (1.5 m) in diameter. This format is superior to broadcast HDTV due to its higher bandwidth and, of course, the ability to do non-realtime optimization of the encoding, which is not possible with broadcast HDTV. The Crown glass process was used up to the mid-1800s. Comprising less than 100 titles and utilizing a 28-Mbit/s MPEG2 stream at 720p or 1080i with either Dolby Digital 5.1 or DTS encoding, D-Theater is an encrypted D-VHS format, and only D-Theater capable D-VHS players can play back these tapes. Eventually some of the Venetian glass workers moved to other areas of northern Europe and glass making spread with them. Aside from scarce Japanese analog MUSE-encoded laser discs that are no longer produced, as of 2005 the only current available prerecorded HD media is D-Theater.

The centre for glass making from the 14th century was Venice, which developed many new techniques and became the centre of a lucrative export trade in dinner ware, mirrors, and other luxury items. This encryption can prevent someone from recording content at all or simply limit the number of copies. Until the 12th century, stained glass (i.e., glass with some colouring impurities, usually metals) was not widely used. This content is protected by encryption known as 5C. This technique was perfected in 13th century Venice. As of July 2004, boxes are not included in the FCC mandate. The 11th century saw the emergence, in Germany, of new ways of making sheet glass by blowing spheres, swinging these out to form cylinders, cutting these while still hot, and then flattening the sheets. None of the DBS providers have offered this feature on any of their supported boxes.

From this point on, northern glass differed significantly from that made in the Mediterranean area, where soda remained in common use. As part of the FCC's "plug and play" agreement, cable companies are required to provide customers that rent HD set-top boxes with a set-top box with "functional" Firewire (IEEE 1394) upon request. About 1000 AD, an important technical breakthrough was made in Northern Europe when soda glass was replaced by glass made from a much more readily available material: potash obtained from wood ashes. Analog tape recorders with bandwidth capable of recording analog HD signals such as W-VHS recorders are no longer produced for the consumer market and are both expensive and scarce in the secondary market. These form an important link between Roman times and the later importance of that city in the production of the material. Realtime MPEG-2 compression of an uncompressed digital HDTV signal is also prohibitively expensive for the consumer market at this time, but should become inexpensive within several years (although this is more relevant for consumer HD camcorders than recording HDTV). Glass objects from the 7th and 8th centuries have been found on the island of Torcello near Venice. However, the massive amount of data storage required to archive uncompressed streams make it unlikely that an uncompressed storage option will appear in the consumer market soon.

When gem-cutters learned to cut glass, they found clear glass was an excellent refractor of light, the popularity of cut clear glass soared, that of coloured glass diminished. D-VHS digitally records a 28.2-Mbit stream onto a classic VHS tape, using a FireWire (IEEE 1394) digital transport to carry a compressed MPEG-2 Transport Stream from the tuning device to the recorder. Glassmakers learned to make coloured glass by adding metallic compounds and mineral oxides to produce brilliant hues of red, green, and blue - the colours of gemstones. In the U.S., the only current archival option is D-VHS. Common glass today usually has a slight green or blue tint, arising from these same impurities. HDTV can be recorded to D-VHS (Data-VHS), W-VHS, to an HDTV-capable digital video recorder such as DirecTV's high-definition TiVo or Dish Network's DVR 921 or 942, or to a computer equipped with an HDTV capture card. This colour is caused by the varying amounts of naturally occurring iron impurities in the sand. Lower-resolution sources like regular DVDs may be upscaled to the native resolution of the TV.

The colour of "natural glass" is green to bluish green. An HDTV-compatible TV usually uses a 16:9 aspect ratio display with an integrated ATSC tuner. This was the discovery of glassblowing, both free-blowing and mould-blowing. In the United States, HDTV specifications are defined by the ATSC. In the first century BC, somewhere at the eastern end of the Mediterranean, a new invention caused a true revolution in the glass industry. Viewers without HDTV sets will continue to receive their television programming through analog transmission approaches. As time passed, it was discovered (most likely by a potter) that if glass is heated until it becomes semi-liquid, it can be shaped and left to cool in a new, solid, independently standing shape. Viewers with HDTV sets will receive picture resolution six times sharper than standard definition analog sets.

Small pieces of coloured glass were considered valuable and often rivalled precious gems as jewellery items. In January 2006, Televisa's XEFB-TV and Multimedios' XHAW-TV in Monterrey, Nuevo Leon began HDTV transmissions on UHF channels 48 and 50, respectively. The earliest use of glass was as a coloured, opaque, or transparent glaze applied to ceramics before they were fired. San Antonio in Tijuana, Mexico with 403,000 watts, directed primarily northward at San Diego. Glass was made from sand, plant ash and lime. This affiliate of the American Fox TV Network is on UHF channel 23 broadcasting from Mt. During the Roman Empire many forms of glass were created, usually for vases and bottles. XETV in Tijuana, Baja California - across the border from San Diego, California - is on the air in HDTV using 720p format.

In the first century BC the technique of blowing glass was developed and what had once been an extremely rare and valuable item became much more common. And one retailer, Elektra, started shipping televisions with HDTV receivers to support this broadcast. Glass making instructions were first documented in Egypt around 1500 BC, when glass was used as a glaze for pottery and other items. Also, TV Azteca has planned to broadcast the Mexican football tournament in HDTV. Naturally occurring glass, such as obsidian, has been used since the stone age. Phase Two of the national rollout will bring HDTV services to six additional cities (Matamoros, Reynosa, Nuevo Laredo, Ciudad Juarez, Mexicali and Tijuana) through the first half of 2006. New coloured glasses are frequently discovered. By the third quarter of 2006, HDTV transmissions will be available in Mexico City, Guadalajara and Monterrey.

The chemistry involved is complex and not well understood. The launch will be carried out in two phases. The way the glass is heated and cooled can significantly affect the colors produced by these compounds. In 2005, TV Azteca signed a deal with Harris Corporation's broadcast communications division for digital TV transmitters and HDTV encoding equipment to bring high-definition TV to nine Mexican cities. Silver compounds (notably silver nitrate) can produce a range of colors from orange-red to yellow. During the first half of 2005, at least one cable provider in Mexico City (Cablevision) has begun to offer 5 HDTV channels to subscribers purchasing a digital video recorder (DVR). Uranium glass is typically not radioactive enough to be dangerous, but if ground into a powder, such as by polishing with sandpaper, and inhaled, it can be carcinogenic. Some events are now broadcast in high definition.

Uranium (0.1 to 2%) can be added to give glass a fluorescent yellow or green colour. Mexican television company Televisa made experimental HDTV broadcasts in the early-1990s, in collaboration with Japan's NHK. Metallic gold, in very small concentrations (around 0.001%), produces a rich ruby-coloured glass, while lower concentrations produces a less intense red, often marketed as "cranberry". It is required that at least 10 hours of HD content to be broadcast on a weekly basis during the first year of commercial digital service. Adding titanium produces yellowish-brown glass. From 2005, digital services are available in all the country. Nickel, depending on the concentration, produces blue, or violet, or even black glass. After a long controversy between the government and broadcasters, ATSC was chosen over DVB-T.

Pure metallic copper produces a very dark red, opaque glass, which is sometimes used as a substitute for gold in the production of ruby-coloured glass. It is reported that two million HD receivers have been sold in Japan already. 2 to 3% of copper oxide produces a turquoise colour. Japan terrestrial broadcast of HD via ISDB-T started in December 2003. Tin oxide with antimony and arsenic oxides produce an opaque white glass, first used in Venice to produce an imitation porcelain. The old system is not compatible with the new digital standards. Small concentrations of cobalt (0.025 to 0.1%) yield blue glass. Japan had pioneered HDTV for decades with an analog implementation.

Like manganese, selenium can be used in small concentrations to decolorize glass, or in higher concentrations to impart a reddish colour. The purpose of the label is create a single norm to simplify the purchase of a HDTV in Europe. Manganese can be added in small amounts to remove the green tint lent by iron, or in higher concentrations to give glass an amethyst colour. A label "HD-ready" has been created to inform consumers of the benefits of High Definition. Metals and metal oxides are added to glass during its manufacture to change its colour. Although most of these channesl are pay tv, there are some free to air hd stations available(Prosieben & Sat 1), as well as technical transmissions by satellite. sol gel is a good example of glass prepared in this way. As for 2006, there has been a slow but steady increase in the number of HD channels available to european viewers in many countries.

By polymerizing glass it is possible to embed active molecules, such as enzymes, to add a new level of functionality to the glass vessels. Commercial HDTV services began in 2004 with Euro1080, an Belgian MPEG2/DVB-S pay channel. Putting in additives that modify the properties of glass is problematic, because the high temperature of preparation destroys most of them. CBC officially launched HDTV programming on March 5, 2005. An innovative way for making glass involves preparation by polymerization. as of early-2005. Large amounts of iron are used in glass that absorbs infrared energy, such as heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths (biologically damaging ionizing radiation). CHUM Limited's Citytv in Toronto was the first HDTV broadcaster in Canada, however very few shows are shown in HDTV beyond the well-known ones such as CSI, ER, etc.

Thorium oxide gives glass a high refractive index and low dispersion, and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern glasses. Other networks are continuing to announce availability of HD signals. Adding barium also increases the refractive index. Global joined the crowd in late-2004. Lead glass, such as lead crystal or flint glass, is more 'brilliant' because the increased refractive index causes noticeably more "sparkles", while boron may be added to change the thermal and electrical properties, as in Pyrex. They were also the first to broadcast a terrestrial HD digital ATSC signal in Canada. As well as soda and lime, most common glass has other ingredients added to change its properties. CTV Toronto broadcast in HD along with its western counterpart, BC CTV.

Soda-lime glasses account for about 90% of manufactured glass. stations plus some PBS feeds and a couple of pay-TV movie channels. The resulting glass contains about 70% silica and is called a soda-lime glass. Bell ExpressVu, a Canadian satellite company, Rogers Cable and Videotron provide somewhat more than 21 HDTV channels to their subscribers including TSN HD, SportsNet HD, Discovery HD (Canadian Edition), The Movie Network HD, and several U.S. However, the soda makes the glass water-soluble, which is obviously undesirable, so lime (calcium oxide, CaO) is the third component, added to restore insolubility. In Canada, on November 22, 2003, CBC had their first broadcast in HD, in the form of the Heritage Classic outdoor NHL game between the Edmonton Oilers and the Montreal Canadiens. One is soda (sodium carbonate Na₂CO₃), or potash, the equivalent potassium compound, which lowers the melting point to about 1000 °C (1800 °F). A complete testbed is expected for 2006 (see http://sbtvd.cpqd.com.br/ for updates).

Pure silica (SiO₂) has a melting point of about 2000 °C (3600 °F), and while it can be made into glass for special applications (see fused quartz), two other substances are always added to common glass to simplify processing. Brazilian universities, research and government institutions are discussing the best policies for a digital television system for use in Brazil. Collecting obsidian from national parks and some places may be prohibited by law, but the same toolmaking techniques can be applied to industrially-made glass. However, most Australian DTV broadcasters are still experimenting with HDTV transmission and DTV delivery. Obsidian is a raw material for flint knappers, who have used it to make extremely sharp knives since the stone age. Most cities in Australia that have a population of 40,000 or greater have at least one terrestrial DTV channel available (for example, Albany, Western Australia, has had DTV available for almost a year as of May, 2005). This glass is called obsidian, and is usually black with impurities. Australia started HD broadcasting in January 2001, but only in August 2003 was HD content mandated.

Glass is sometimes created naturally from volcanic magma. See also: COUNCIL DIRECTIVE 92/38/EEC of 11 May 1992. The glasses are arranged by composition, refractive index, and Abbe number. The HD-MAC standard was abandoned in 1993, and since then all EU and EBU efforts have focused on the DVB system (Digital Video Broadcasting), which allows both SDTV and HDTV. For example, BK7 is a low-dispersion borosilicate crown glass, and SF10 is a high-dispersion dense flint glass. Thus, analogue HDTV could not replace conventional SDTV (terrestrial) PAL/SECAM, making HD-MAC sets unattractive to potential consumers. Glasses used for making optical devices are commonly categorized using a six-digit glass code, or alternatively a letter-number code from the Schott Glass catalogue. HD-MAC could be used only by cable and satellite providers, where there is a wider bandwidth available.

Amorphous SiO₂ is also used as a dielectric material in integrated circuits, due to the smooth and electrically neutral interface it forms with silicon. Another reason for HD-MAC's failure is that it was not realistic to use 36 MHz for a high-definition signal in terrestrial broadcasting (SDTV uses 6-, 7- (VHF), or 8-MHz (UHF)). Undersea cables have sections doped with erbium, which amplify transmitted signals by laser emission from within the glass itself. HD-MAC (the high-definition variant of MAC) was left for transcontinental satellite links, however. Individual fibres are given an equally transparent core of SiO₂/GeO₂ glass, which has only slightly different optical properties (the germanium contributing to a higher index of refraction). Owing to the advance of technology and the launch of middle-powered satellites by SES Astra, broadcasters could avoid MAC, and lower transmission costs. This type of glass can be made so pure that hundreds of kilometres of glass are transparent at infrared wavelengths in fibre optic cables. It was required that all high-powered satellite broadcasters use MAC from that year.

Pure SiO₂ glass (also called fused quartz) does not absorb UV light and is used for applications that require transparency in this region, although it is more expensive. However, it never became popular among broadcasters. This is due to the addition of compounds such as soda ash (sodium carbonate). The European Commission established a European standard for uncompressed digital HDTV in a 1986 directive (MAC). Ordinary glass does not allow light at a wavelength of lower than 400 nm, also known as ultraviolet light or UV, to pass. It broadcasts the same programs as BS-digital channel 103, but will end sometime in 2007. The transparency is due to an absence of electronic transition states in the range of visible light, and to the fact that such glass is homogeneous on all length scales greater than about a wavelength of visible light (inhomogeneities cause light to be scattered, breaking up any coherent image transmission). Though Japan has since switched to a digital HDTV system based on ISDB, the original MUSE-based BS Satellite channel 9 (NHK BS Hi-vision) is still being broadcast.

One of the most obvious characteristics of ordinary glass is that it is transparent to visible light (not all glassy materials are). The Japanese MUSE system, developed by NHK Science and Technical Research Laboratories (STRL) in the 1980s, employed filtering tricks to reduce the original source signal to decrease bandwidth utilization. Common glass contains about 70% amorphous silicon dioxide (SiO₂), which is the same chemical compound found in quartz, and its polycrystalline form, sand. Japan began broadcasting analog HDTV signals in the early 1990s using an interlaced resolution of 1035 lines (1035i). These properties can be modified, or even changed entirely, with the addition of other compounds or heat treatment. Japan has the earliest working HDTV system still in use, with design efforts going back to 1979. Glass is, however, brittle and will break into sharp shards. It was transmitted only on VHF channels, and a French 819-line TV channel occupied 14 MHz of bandwidth.

These desirable properties lead to a great many uses of glass. It was used only for black-and-white TV; color TV in 819-line SECAM never went beyond the experimental stage. In its pure form, glass is a transparent, relatively strong, hard-wearing, essentially inert, and biologically inactive material which can be formed with very smooth and impervious surfaces. It was discontinued in 1986. The remainder of this article will be concerned with a specific type of glass—the silica-based glasses in common use as a building, container or decorative material. The French "755i" 819-line HDTV system was used in only France, Belgium and Monaco, and in France only for the first French TV channel. The term enamel is used to describe glass fused as a decorative or functional coating on metal. When, in the late-1960s, a second TV channel and color TV were introduced in Europe, the UK dropped its 405-line TV system (completely in 1985) and France dropped its 819-line system, making all European countries agree to use 625 lines (576i) for their TV transmissions.

Germanic tribes used the word glaes to describe amber, recorded by Roman historians as glaesum. Anglo-Saxons used the word glaer for amber. The French 819-line (or 755i) HDTV system was introduced in the 1950s. glaes. The French TV system thus became the world's first HDTV system, and, by today's standards, the French system could be called 755i (not all lines could be used for the actual image — some lines were lost during the vertical retrace). glas, A.S. The UK used 405 lines, most other countries 625 lines (both numbers include the vertical gap, the actual resolution were lower), but France decided in 1948 to go for 819 lines. The word glass comes from Latin glacies (ice) and corresponds to German Glas, M.E. in the late-1940s and early-1950s, different countries used different resolutions.

The resulting solid is amorphous, not crystalline like the sugar was originally, which can be seen in its conchoidal fracture. When Europe resumed TV transmissions after WWII, i.e. A simple example is when table sugar is melted and cooled rapidly by dumping the liquid sugar onto a cold surface. Most professionals in 3D technology foresee greater use of stereo visuals and animation as HDTV becomes the norm. The materials definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly to below its glass transition temperature, thereby not giving enough time for a regular crystal lattice to form. The Discovery HD channel has already provided a small amount of science programing in 3D. . A number of 3D stereoscopic major animation films like Polar Express, Disney's Chicken Little and 6 more scheduled for 2006 release, will be likely to be sold for home display in one or more of the new HD disk systems in 3D.

This (along with chromatic aberration and other effects) limits the size of refracting telescopes, with the largest refractor in the World being the Yerkes Observatory telescope with a diameter of 102cm. For more technical details see the articles on HDV, ATSC, DVB, and ISDB, respectively. The result is a loss of focus and is sometimes argued to occur not because of the liquid properties of glass but rather sagging of the telescope itself, but this is not correct. New HD compression and recording formats such as HDV use rectanglar pixels for more efficient compression and to open HDTV aquisition for the consumer market. This sag happens because the lens is only supported around its edge. The pixel aspect ratio of native HD signals is 1.0, or 1 pixel length = 1 pixel width. Glass in Refracting Telescopes, with objective lenses greater than 105cm in diameter, is observed to sag under its own under weight over time. HDTV is capable of "theater-quality" audio because it uses the Dolby Digital (AC-3) format to support "5.1" surround sound.

Similarly, it should not be possible to see Newton's rings between decade-old fragments of window glass—but this can in fact be quite easily done. Recommended receiver is Humax PR-HD 1000, but others are announced as well as PCI cards. If glass flows at a rate that allows changes to be seen with the naked eye after centuries, then changes in optical telescope mirrors should be observable (by interferometry) in a matter of days—but this also is not observed. Some German broadcasters already use MPEG-4 together with DVB-S2 (ProSieben, Sat1 and Three Premiere Channels). If medieval glass has flowed perceptibly, then ancient Roman and Egyptian objects should have flowed proportionately more—but this is not observed. Some broadcasters also plan to use MPEG-4. In layperson's terms, he wrote that glass at room temperature is very strongly on the solid side of the spectrum from solids to liquids. Although MPEG-2 supports up to 4:2:2 YUV chroma subsampling and 10-bit quantization, HD broadcasts use 4:2:0 and 8-bit quantization to save bandwidth.

Phys, 66(5):392-5, May 1998). MPEG-2 is most commonly used as the compression codec for digital HDTV broadcasts. J. NBC, Universal-HD (both owned by General Electric), CBS, HBO-HD, INHD, HDNet and TNT currently broadcast 1080i content. Hence, the relaxation period (characteristic flow time) of cathedral glasses would be even longer" (Am. In North America, Fox, ABC, and ESPN (ABC and ESPN are both owned by Disney) currently broadcast 720p content. Zanotto states "...the predicted relaxation time for GeO₂ at room temperature is 10³² years. An LCD capable of native 1080i resolution still costs over a thousand US dollars.

Writing in the American Journal of Physics, physicist Edgar D. 720p appears at full resolution on a common 1280x1024 LCD, which can be found for under $250. double-glazing. 720p Video also has lower storage and decoding requirements than 1080i or 1080p, and few people possess displays capable of displaying the 1920x1080 resolution without scaling. application of a self-cleaning catylist. In addition, 720p is used more often with internet distribution of HD video, as all computer monitors are progressive, and most graphics cards do a sub-optimal job of de-interlacing video in real time. chemical strengthening. In general, 720p is more appropriate for fast action as it uses progressive fields, as opposed to 1080i which uses interlaced fields and thus can have a degredation of image quality with fast motion.

toughening. The format depends on the broadcast company if destined for television broadcast, however in other scenarios the format choice will vary depending on a variety of factors. laminating. Noncinematic HDTV video recordings are recorded in either 720p or 1080i format. figure rolled glass. (See also: Deinterlacing). float (annealed) glass. These may be upconverted to a higher resolution format (720i), but removing the interlace to match the common 720p format may distort the picture or require filtering which actually reduces the resolution of the final output.

polished plate glass. Older (pre-HDTV) recordings on video tape such as Betacam SP are often either in the form 480i60 or 576i50. rolled plate glass. (See also: Telecine). sheet glass. One film frame is held for three video fields, (1/20 of a second) and then the next is held for two video fields (1/30 of a second) and then the process repeats, thus achieving the correct film rate with two film frames shown in 1/12 of a second. cylinder glass. In countries using the NTSC standard, (60 fps) a technique called 3:2 pulldown is used.

When shown on television in countries using PAL, film must be converted to 25 frames per second by speeding it up by 4%. Depending on the available bandwidth and the amount of detail and movement in the picture, the optimum format for video transfer is thus either 720p24 or 1080p24. Photographic film destined for the theatre typically has a high resolution and is photographed at 24 frame/s. The lossy compression that is used in all digital HDTV systems will then cause the picture to be distorted.

On the other hand, a very high resolution may require more bandwidth than is available. The field and frame rate should match the source, as should the resolution. The optimum format for a broadcast depends on the type of media used for the recording and the characteristics of the content. In addition, the technical standards for broadcasting HDTV are also able to handle 16:9 aspect ratio pictures without using letterboxing, thus further increasing the effective resolution for such content.

HDTV has at least twice the resolution of SDTV, thus allowing much more detail to be shown compared to analog television or regular DVD. The most common are:. Most HDTV systems support some standard resolutions and frame or field rates. For example 24p means 24 progressive frames per second and 50i means 25 interlaced frames per second.

A frame or field rate can also be specified without a resolution. It can then usually be assumed to be either 50 or 60, except for 1080p which is only supported as 1080p24, 1080p25 or 1080p30 by consumer HDTV displays. Often the frame or field rate is left out. The format 1080i50 is 1920 × 1080 pixels, interlaced encoding with 50 fields (25 frames) per second.

For example, the format 720p60 is 1280 × 720 pixels, progressive encoding with 60 frames per second. In the context of HDTV, the formats of the broadcasts are referred to using a notation describing:. . This is a confusing use of the terms HD and HDTV.

Even HD-ready sets do not necessarily have enough pixels to display video to the 1080-line (1920x1080) or 720-line (1280x720) HD standards in full resolution without interpolation, and HD-compatible sets are often just standard-definition sets with an HDMI input. They indicate that a TV or display is able to accept video over an HDMI connection, using a new connector design, the main purpose of which seems to be to ensure that digital video is only passed over an interface which, by agreement, incorporates copyright protection. The terms HD ready and HD compatible are being used around the industrial world for marketing purposes. The world used analog PAL, NTSC, SECAM and other standards for over half a century.

Most patents were expiring by the end of World War II leaving the market wide open and no worldwide standard for television agreed upon. It was patent interference lawsuits and deployment issues given the tumultuous financial climate of the late 20's and 30's. Farnsworth, John Logie Baird and Vladimir Zworkin had each developed competing TV systems but resolution was not the issue that separated their substantially different technologies. Historically, the term high-definition television was also used to refer to television standards developed in the 1930s to replace the early experimental systems, although, not so long afterwards, Philo T.

Except for early analog formats in Europe and Japan, HDTV is broadcast digitally, and therefore its introduction sometimes coincides with the introduction of digital television (DTV). High-definition television (HDTV) means broadcast of television signals with a higher resolution than traditional formats (NTSC, SÉCAM, PAL) allow. TV Azteca Plans HDTV Mexican Rollout. High Definition (HD) Image Formats for Television Production, technical report from the EBU.

High Definition for Europe - a progressive approach, article from the EBU technical review . Images formats for HDTV, article from the EBU technical review . DVB HDTV standard. DTV channel protection ratios.

United States Federal Standard 1037C. MUSE had a bit-reduced stereo audio transmission system that was notable in its design as it was not psychoacoustical like Musicam. Considering the technological limitations of the time, MUSE was a very cleverly-designed analog system. Whole-camera pans would result in a loss of 50% of horizontal resolution.

Stationary images were transmitted at full resolution. Moving images were thus blurred in a manner similar to using 16mm movie film for HDTV projection. In the typical setup, three picture elements on a line were actually derived from three separate scans. The increased clarity, and detail make larger screen sizes more comfortable and pleasing to watch.

Both systems will usually play current DVDs, and attempt to extract a near-HDTV-quality image from them, but they are not compatible with each other. One is called HD DVD, the other is Blu-ray. Two new pre-recorded disc formats will be available in spring 2006. The gaps between scaning lines are smaller or gone.

The visual information is about 2-5 times more detailed overall. The colors will generally look more realistic, due to the cleaner signal. Most HD programming and films will be presented in the 16x9 proportioned, semi-widescreen format (though some films created in even wider ratios will still display "letterbox" bars on the top and bottom of even 16:9 sets.) Older films and programming that retain their 4:3 ratio display will be presented in a version of letterbox commonly called "pillar box", displaying bars on the right and left of 16:9 sets (rendering the term "fullscreen" a misnomer.) Or, one can usually choose to enlarge the image to fill the screen, however this option will display a distorted, stretched-out picture. You would never get a snowy, washed out, image, or vertical rolling.

All commercial HD is digital, so the signal will either deliver a good picture, a picture with large pixelation, a series of frozen pictures, or no picture. 60i (NTSC). 50i (PAL). 60p.

50p. 30p. 25p. 24p (cinematic film).

NTSC is typically 720x480. Number of frames or fields per second. Progressive frames (p) or interlaced fields (i). The number of lines in the display resolution.