Video is a 'picture' in motion. It is an output of a certain
light or electrical signal . From this report we will learn about the
evolution and development of storage, and transmission of videos as well
as the different types of technlogy that evolved that is used for output.
Different formats will also be covered and the person behind the development
of this area.
People Involved & Their Contribution
Anglo-American photographer and moving picture pioneer, known for his
photographs of animals and people in motion. He was born Edward James
Muggeridge in Kingston-on-Thames, where he was educated. After emigrating
to the United States, he became a photographer for the Coast and Geodetic
Survey. In 1872 he was accused of murdering his wife's lover, and although
he was acquitted, he was obliged to travel in Central and South America
for several years, photographing railway construction. In 1877 he demonstrated
through photographs that when a horse runs, there is a moment when all
of the animal's feet are off the ground, and that the feet are tucked
beneath the animal at that moment. In 1881 he invented the zoopraxiscope,
a device by which he reproduced on a screen horse races, the flights of
birds, and athletic contests. He wrote The Horse in Motion (1878) and
Animal Locomotion (11 vols., including 100,000 photographic plates, 1887).
Portions of the latter work were published under the titles Animals in
Motion and The Human Figure in Motion (1901).
American inventor and philanthropist, who played a leading role in transforming
photography from an expensive hobby of a few devotees into a relatively
inexpensive and immensely popular pastime. He was born in Waterville,
New York, and was self-educated. In 1884 Eastman patented the first film
in roll form to prove practicable; in 1888 he perfected the Kodak camera,
the first camera designed specifically for roll film. In 1892 he established
the Eastman Kodak Company, at Rochester, New York, one of the first firms
to mass-produce standardized photography equipment. This company also
manufactured the flexible transparent film, devised by Eastman in 1889,
which proved vital to the subsequent development of the motion picture
industry. Eastman was associated with the company in an administrative
and an executive capacity until his death, and he contributed much to
the development of its notable research facilities. He was also one of
the outstanding philanthropists of his time, donating more than US$75
million to various projects. Notable among his contributions were a gift
to the Massachusetts Institute of Technology and endowments for the establishment
of the Eastman School of Music in 1918 and a school of medicine and dentistry
in 1921 at the University of Rochester.
Thomas Alva (1847-1931),
American inventor, whose development of a practical electric light bulb,
electric generating system, sound-recording device, and film projector
had profound effects on the shaping of modern society.
In 1888 he invented the kinetoscope, the first machine
to produce films by a rapid succession of individual views. Among his
later noteworthy inventions was the Edison storage battery (an alkaline,
nickel-iron storage battery), the result of many thousands of experiments.
The battery was extremely rugged and had a high electrical capacity per
unit of weight. He also developed a gramophone in which the sound was
impressed on a disc instead of a cylinder. This gramophone had a diamond
needle and other improved features. By synchronizing his gramophone and
kinetoscope, he produced, in 1913, the first sound film.
(1864-1948) and Auguste Lumiere (1862-1954),
French photographic manufacturers, inventors, and pioneer film-makers
who invented an early picture camera in 1895 that also functioned as a
projector and printer. They called their device the Cinématographe, from
which the word "cinema" is derived. Their short film, La Sortie des Usines
Lumière (Workers Leaving the Lumière Factory), was shown in public for
the first time in 1895 at the Grand Café on the Boulevard des Capuchines
in Paris and is considered to be the first film. The brothers produced
many such films in the same year, for example, L'Arrivée d'un Train en
Gare (The Arrival of a Train at the Station) and Le Repas de Bébé (Feeding
the Baby), as well as the first newsreel and the first documentaries.
Sir William (1832-1919),
British chemist and physicist, born in London and educated at the Royal
College of Chemistry. In 1859 he founded the Chemical News, and in 1864
he became editor of the Quarterly Journal of Science. Crookes was knighted
in 1897 and received the Order of Merit in 1910. Crookes conducted research
in a number of fields. He discovered the element thallium and developed
a sodium amalgamation process for the separation of silver and gold from
their ores. In applied chemistry he worked on such problems as the treatment
of sewage, the manufacture of beet sugar, and the dyeing of textiles.
His most important work, however, was in the investigation of the conduction
of electricity in gases. He developed the Crookes tube and in it produced
cathode rays for the first time. He also invented the radiometer and the
spinthariscope, a particle detector.
John Logie (1888-1946),
Scottish engineer, pioneer in the development of television. Born in Helensburgh,
Argyll and Bute, on August 13, 1888, Baird was forced to resign from his
position as an electrical engineer through persistent ill health, and
he retired early, in 1922, to Hastings, East Sussex. Under these circumstances,
he used his time to research ways of transmitting pictures. Although various
scientists in different parts of the world, for example, in Germany and
the United States, were also conducting experiments around the same time,
Baird was the first to hold a successful public demonstration, on January
27, 1926, of his primitive television system, in Soho, London. Later that
year he also became the first to transmit pictures of objects in motion,
at the Royal Institution in London, and to show his "noctovision", a system
that used infrared rays to communicate pictures from a darkened room.
From then on Baird continued his research: he transmitted pictures between
London and Glasgow using telephone lines in 1927 and between London and
New York the following year using radio waves; he also helped to pioneer
colour television and stereoscopic television, which gave greater depth
and solidity to the picture. His company, Baird Television Development
Company, provided the first programme for the British Broadcasting Corporation
(BBC) on September 30, 1929. The early television systems transmitted
pictures made up of 30 lines; Baird was instrumental in developing a more
complex system that used more lines and gave the picture greater definition.
Eventually, however, his 240-line mechanical system was supplanted by
the 405-line electronic system invented by EMI in conjunction with Marconi
(nowadays, television pictures consist of between 525 and 819 lines).
Video Recording, process of recording still or
moving images electronically, rather than photochemically as in photographic
The techniques used to record images on videotape are
similar to those used in sound recording and reproduction. Electrical
signals from a television camera (or from a television camera via a television
receiver) are stored as patterns of magnetized regions of iron oxide on
magnetic tape. When the recorded tape is played back, the original signals
are generated. These signals can then be disseminated by broadcast antenna
or by cable to television receivers that translate the signals into images
and sounds. Videotape recorder/playback systems for domestic use are connected
directly to a television receiver. Unlike motion picture film, videotape
does not require processing, and so may be played back immediately. This
makes possible the instant replay common to televised sporting events.
Audio signals have a bandwidth, or frequency range, of about 20,000 Hz
and can be recorded on magnetic tape that passes over the record/playback
head relatively slowly. Video signals, on the other hand, such as the
signal that modulates the carrier wave of a television transmitter, have
a bandwidth as high as 6 MHz and therefore require a much higher scanning
speed to accommodate the 300-fold increase in information to be recorded
or played back. The first magnetic video recorders, built in the early
1950s, relied on very fast tape speeds-up to 914 cm (360 in) per second-to
record and reproduce images of an acceptable quality. Such recorders were
not really practical, and the television industry continued to use motion
picture film for recording live television programmes. These were referred
to as kinescope recordings.
However, in 1956 a transverse scanning system of video
recording and playback was developed by engineers of the Ampex company
in the United States. In this system, called quadruplex, four record/playback
tape heads are mounted on the circumference of a drum that rotates rapidly
(14,400 rpm) at a right angle to the direction of tape movement. In this
manner, the heads scan the video tracks on the tape with head-to-tape
speeds equivalent to 3,810 cm (1,500 in) per second. The tape itself travels
slowly: either 38 cm (15 in) or 19 cm (7 1/2 in) per second. The sound
track and the picture control track run linearly near the edges of the
tape and are scanned by fixed heads. The picture control track generates
signals that serve to adjust the speed of the rotating drum so that each
head is aligned directly over the correct part of each recorded video
track. The tape used in quadruplex systems is 5 cm (2 in) wide, and a
2.5-cm (1-in) length of tape contains 64 transverse tracks-enough for
two frames of 525 lines each. This system came to be generally used in
the television industry from the end of the 1950s.
Helical Video Tape
The early helical scan systems employed tape widths of 1.25 cm (y in)
or 1.9 cm (• in) housed in tape cassettes. In the early 1990s, new helical
scan recorders that record the television signal in digital form were
In the 1960s a variant of this scanning principle was developed, called
helical scan (or slant-track scan). At first this had a much slower head-to-tape
speed than the quadruplex system, and the maximum bandwidth was only 3
MHz. Picture resolution was therefore inferior to that of quadruplex.
In helical scan, one or two record/playback heads are mounted on the circumference
of a drum that rotates rapidly in the same direction as the tape transport.
The tape is wrapped round the drum in a helical manner. The wrap angle
(that is, the angle between initial and final contact with the drum) is
anywhere from 180° to 360°, depending on the make of the recorder. The
early helical scan systems, developed for domestic or professional use,
employed tape widths of 1.25 cm (1/2 in) or 1.9 cm (3/4 in) housed in
tape cassettes. Video cassette recorders (VCRs) became relatively inexpensive
by the early 1980s and were commonly sold for domestic use. Watching videos
changed trends in television viewing; in Britain, around three quarters
of households have at least one VCR. From the late 1980s onward, 8-mm
(3/10-in) magnetic tapes became much more common, especially for use in
camcorders (combination video cameras and tape recorders). The smaller
tape cassette size and long recording time of 2 hours makes the 8-mm format
attractive for use in lightweight, portable equipment. Since their introduction,
both the 1/2-in and the 8-mm formats used for domestic VCRs have been
augmented by improved versions-Super-VHS, Hi8 and Digital8, respectively-that
can handle greater bandwidths. The result is better picture definition
or detail approaching that of professional video recorders. At the end
of the 1970s new models of helical scan recorders using 2.54-cm (1-in)
tape and higher-tape speeds than domestic VCRs were developed that could
finally equal the quality of quadruplex machines. Manufacturers eventually
standardized on two variants called "B format" and "C format", with the
latter proving more popular with television broadcasters as the new standard
recording device that has displaced quadruplex machines.
An example of digital recording in a Digital8 format. CX Systems Advertisement.
Starting from 1991, new helical scan recorders that record the television
signal in digital form began to be adopted by broadcasters. There are
many varieties from different manufacturers, but at the highest-quality
end the agreed international standards are the D1, D2, and D3 formats.
All of these use tape in cassettes, with widths of 19 mm (3/4 in) in the
first two cases, and 13 mm (1/2 in) in the latter. Before being recorded
on to the tape, the television signal in its standard analogue form is
digitized by an analogue-to-digital convertor, and then further encoding
for error correction is applied to the resulting string of bits. After
recording and playback, the process can be reversed to give an analogue
signal for broadcasting. However, the signal can be retained in its digital
form for other purposes, such as applying computer-generated effects.
(TV), system of mass communication, involving the transmission of images
and sounds to distant screens, by electronic means over electrical or
fibre-optic transmission lines or by electromagnetic radiation (radio
waves). TV is a vastly important medium, for a number of reasons: the
amount of time that many people spend watching it (31 hours per week,
for average United States adults, 25 for Britons); its ability to bring
together diverse groups of people in a sense of shared national identity;
and its powerful role as a source of information about experiences other
than the viewer's own. It was the first medium to relay, via communications
satellites, pictures across continents, and it is the prime route to the
public for presenting news and current affairs, including the progress
of wars and political campaigns. It is thus a powerful influence on public
perception and opinion. TV developed in Western Europe and North America,
but has spread across the world. In 1992 there were roughly 16 TV receivers
for every 100 people. However, the distribution of TV is very uneven:
there are around 80 sets per 100 US citizens, but only 2.3 per 100 people
in non-Arab Africa. TV has in general been a very centralized form of
communication, which does not easily permit access and participation.
This is partly because TV transmission and production have been so expensive
that only a few companies could become involved, and also because governments
have strictly regulated who could gain access to the relatively scarce
parts of the electromagnetic spectrum allocated for TV transmission. In
the 1980s, many new forms of TV-related technology, such as cable television
and Direct Broadcast Satellite, began to allow other forms of transmission
and reception, and many governments began to relax their regulations about
who could broadcast. These technological changes have helped bring about
shifts in the cultural significance of TV. For more than 40 years, many
of the most important national events, in a number of countries, have
been experienced as TV events. Examples include the coronation of Queen
Elizabeth II in 1953, the royal wedding of Prince Akihito in Japan in
1959, the annual Super Bowl football match in the United States, and the
reporting of various international crises and political assassinations.
However, some commentators have claimed that the era when TV served as
a source of national bonding is coming to an end, as TV begins to appeal
to smaller and more specific segments of the audience, rather than to
entire societies. In spite of these changes, TV remains probably the most
important form of mass communication of the late 20th century.
Organic EL Screen
Developments on Video Output
Liquid Crystal Displays or LCD can be used as an output for
video much like on a Television. A television uses cathode ray tube as it's
gun to produce an image while an LCD uses liquid crystals. The liquid crystals
are liquified due to the pressure inside it's casing. When an electric current
electrifies a liquid crystal molecule, it produces certain color. Liquid
crystals emit wavelengths of color depending on the temperature and pressure.
temperature is controlled by the electric current that conducts the crystal.
The same manner applies to Plasma Screens. In this medium,
a chemical which is neither in a liquid or in solid state is struck by
electric current and produces color. The difference is that pictures in
plasma screens are sharper, clearer and higher in quality.
Newest development in video output is the Organic EL.
This is developed by Sanyo Electric. Instead of an LCD or plasma, a carbon
compound is used. Though not much information is still gathered on this
new technology, it is believed that Organic EL screens are a lot thinner
than LCD screens and will be used primarily for Mobile phones and computers.