Video is an
electronic
Electronic may refer to:
*Electronics, the science of how to control electric energy in semiconductor
* ''Electronics'' (magazine), a defunct American trade journal
*Electronic storage, the storage of data using an electronic device
*Electronic co ...
medium for the recording,
copying
Copying is the duplication of information or an artifact based on an instance of that information or artifact, and not using the process that originally generated it. With analog forms of information, copying is only possible to a limited degree o ...
, playback,
broadcasting
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...
, and display of
moving visual
The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the ...
media
Media may refer to:
Communication
* Media (communication), tools used to deliver information or data
** Advertising media, various media, content, buying and placement for advertising
** Broadcast media, communications delivered over mass el ...
. Video was first developed for
mechanical television
Mechanical television or mechanical scan television is a television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a si ...
systems, which were quickly replaced by
cathode-ray tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictur ...
(CRT) systems which, in turn, were replaced by
flat panel display
A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment.
Flat-panel displays are thin, lightweight, provide better li ...
s of several types.
Video systems vary in
display resolution
The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is ...
,
aspect ratio,
refresh rate
The refresh rate (or "vertical refresh rate", "vertical scan rate", terminology originating with the cathode ray tubes) is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate ...
, color capabilities and other qualities. Analog and digital variants exist and can be carried on a variety of media, including
radio broadcast
Radio broadcasting is transmission of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based radio sta ...
,
magnetic tape
Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magne ...
,
optical disc
In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc that encodes binary data (bits) in the form of pits and lands on a special material, often aluminum, on one of its flat surfaces. ...
s,
computer files
A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and transf ...
, and
network streaming.
History
Analog video
Video technology was first developed for
mechanical television
Mechanical television or mechanical scan television is a television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a si ...
systems, which were quickly replaced by
cathode-ray tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictur ...
(CRT)
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
systems, but several new technologies for video
display device
A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal the ...
s have since been invented. Video was originally exclusively a
live
Live may refer to:
Arts, entertainment, and media Films
* ''Live!'' (2007 film), 2007 American film
* ''Live'' (2014 film), a 2014 Japanese film
*'' ''Live'' (Apocalyptica DVD)
Music
*Live (band), American alternative rock band
* List of albums ...
technology.
Charles Ginsburg
Charles Paulson Ginsburg (July 27, 1920 – April 9, 1992) was an American engineer and the leader of a research team at Ampex which developed one of the first practical videotape recorders.
Biography
Ginsburg was born on July 27, 1920 in San ...
led an
Ampex
Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name AMPEX is a portmanteau, created by its founder, which stands for Alexander M. Poniatoff Excellence.AbramsoThe History ...
research team developing one of the first practical
video tape recorder
A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were use ...
s (VTR). In 1951, the first VTR captured live images from
television camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). O ...
s by writing the camera's electrical signal onto magnetic
videotape
Videotape is magnetic tape used for storing video and usually sound in addition. Information stored can be in the form of either an analog or digital signal. Videotape is used in both video tape recorders (VTRs) and, more commonly, videocassett ...
.
Video recorders were sold for US$50,000 in 1956, and videotapes cost US$300 per one-hour reel. However, prices gradually dropped over the years; in 1971, Sony began selling
videocassette recorder
A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette
Videotape is magnetic tape ...
(VCR) decks and tapes into the
consumer market
A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. T ...
.
Digital video
Digital video is capable of higher quality and, eventually, much lower cost than earlier analog technology. After the invention of the
DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
in 1997, and later the
Blu-ray Disc
The Blu-ray Disc (BD), often known simply as Blu-ray, is a Digital media, digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and c ...
in 2006, sales of videotape and recording equipment plummeted. Advances in
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
technology allows even inexpensive
personal computer
A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
s and
smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
s to capture, store, edit and transmit digital video, further reducing the cost of
video production
Video production is the process of producing video content for video. It is the equivalent of filmmaking, but with video recorded either as analog signals on videotape, digitally in video tape or as computer files stored on optical discs, hard dri ...
, allowing program-makers and broadcasters to move to
tapeless production
In the field of professional broadcasting, an end-to-end workflow (from ingest to playout) is called ''tapeless'' when part, or all of it, is made without any use of audio tape recorders or videotape machines; video and audio sources being inges ...
. The advent of
digital broadcasting
Digital broadcasting is the practice of using digital signals rather than analogue signals for broadcasting over radio frequency bands. Digital television broadcasting (especially satellite television) is widespread. Digital audio broadcasting is ...
and the subsequent
digital television transition
The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is conv ...
is in the process of relegating analog video to the status of a
legacy technology
In computing, a legacy system is an old method, technology, computer system, or application program, "of, relating to, or being a previous or outdated computer system", yet still in use. Often referencing a system as "legacy" means that it paved ...
in most parts of the world. The development of high-resolution video cameras with improved
dynamic range
Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-1 ...
and
color gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circ ...
s, along with the introduction of high-dynamic-range
digital intermediate
Digital intermediate (typically abbreviated DI) is a motion picture finishing process which classically involves digitizing a motion picture and manipulating the color and other image characteristics.
Definition and overview
A digital intermediat ...
data formats with improved
color depth
Color depth or colour depth (see spelling differences), also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring to ...
, has caused digital video technology to converge with film technology. the usage of
digital cameras
A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile device ...
in
Hollywood
Hollywood usually refers to:
* Hollywood, Los Angeles, a neighborhood in California
* Hollywood, a metonym for the cinema of the United States
Hollywood may also refer to:
Places United States
* Hollywood District (disambiguation)
* Hollywood, ...
has surpassed use of film cameras.
Characteristics of video streams
Number of frames per second
''
Frame rate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...
'', the number of still pictures per unit of time of video, ranges from six or eight frames per second (''frame/s'') for old mechanical cameras to 120 or more frames per second for new professional cameras.
PAL
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
standards (Europe, Asia, Australia, etc.) and
SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
(France, Russia, parts of Africa etc.) specify 25 frame/s, while
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
standards (USA, Canada, Japan, etc.) specify 29.97 frame/s. Film is shot at the slower frame rate of 24 frames per second, which slightly complicates the process of transferring a cinematic motion picture to video. The minimum frame rate to achieve a comfortable illusion of a
moving image
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...
is about sixteen frames per second.
Interlaced vs progressive
Video can be
interlaced
Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This ...
or
progressive. In progressive scan systems, each refresh period updates all scan lines in each frame in sequence. When displaying a natively progressive broadcast or recorded signal, the result is optimum spatial resolution of both the stationary and moving parts of the image. Interlacing was invented as a way to reduce flicker in early
mechanical
Mechanical may refer to:
Machine
* Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement
* Mechanical calculator, a device used to perform the basic operations of ...
and
CRT video displays without increasing the number of complete
frames per second
A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent.
Frame and FRAME may also refer to:
Physical objects
In building construction
*Framing (con ...
. Interlacing retains detail while requiring lower
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
compared to progressive scanning.
In interlaced video, the horizontal
scan line
A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube (CRT) display of a television set or computer monitor.
On CRT screens the horizontal scan lines are visually discernible ...
s of each complete frame are treated as if numbered consecutively, and captured as two ''fields'': an ''odd field'' (upper field) consisting of the odd-numbered lines and an ''even field'' (lower field) consisting of the even-numbered lines. Analog display devices reproduce each frame, effectively doubling the frame rate as far as perceptible overall flicker is concerned. When the image capture device acquires the fields one at a time, rather than dividing up a complete frame after it is captured, the frame rate for motion is effectively doubled as well, resulting in smoother, more lifelike reproduction of rapidly moving parts of the image when viewed on an interlaced CRT display.
NTSC, PAL and SECAM are interlaced formats. Abbreviated video resolution specifications often include an ''i'' to indicate interlacing. For example, PAL video format is often described as ''576i50'', where ''576'' indicates the total number of horizontal scan lines, ''i'' indicates interlacing, and ''50'' indicates 50 fields (half-frames) per second.
When displaying a natively interlaced signal on a progressive scan device, overall spatial resolution is degraded by simple
line doubling
A line doubler is a device or algorithm used to deinterlace video signals prior to display on a progressive scan display.
The main function of a deinterlacer is to take an interlaced video frame which consists of 60 two-field interlaced fields ...
—artifacts such as flickering or "comb" effects in moving parts of the image which appear unless special signal processing eliminates them.
A procedure known as
deinterlacing
Deinterlacing is the process of converting interlaced video into a non-interlaced or Progressive scan, progressive form. Interlaced video signals are commonly found in analog television, digital television (HDTV) when in the 1080i format, some D ...
can optimize the display of an interlaced video signal from an analog, DVD or satellite source on a progressive scan device such as an
LCD television
Liquid-crystal-display televisions (LCD TVs) are television sets that use liquid-crystal displays to produce images. They are, by far, the most widely produced and sold television display type. LCD TVs are thin and light, but have some disadvantag ...
, digital
video projector
A video projector is an image projector that receives a video signalling (telecommunication), signal and projects the corresponding image on a projection screen using a lens (optics), lens system. Video projectors use a very bright ultra-high-per ...
or plasma panel. Deinterlacing cannot, however, produce
video quality
Video quality is a characteristic of a video passed through a video transmission or processing system that describes perceived video degradation (typically, compared to the original video). Video processing systems may introduce some amount of dist ...
that is equivalent to true progressive scan source material.
Aspect ratio
Aspect ratio describes the proportional relationship between the width and height of video screens and video picture elements. All popular video formats are
rectangular
In Euclidean geometry, Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°); or a par ...
, and so can be described by a ratio between width and height. The ratio width to height for a traditional television screen is 4:3, or about 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack (also known as the
Academy ratio
The Academy ratio of 1.375:1 (abbreviated as 1.37:1) is an aspect ratio of a frame of 35 mm film when used with 4-perf pulldown.Monaco, James. ''How to Read a Film: The Art, Technology, Language, History and Theory of Film and Media''. Rev. ...
) is 1.375:1.
Pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the smal ...
s on computer monitors are usually square, but pixels used in
digital video
Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...
often have non-square aspect ratios, such as those used in the PAL and NTSC variants of the
CCIR 601
ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601 (or its former name CCIR 601) is a standard originally issued in 1982 by the Comité consultatif international pour la radio, CCIR (an organization, ...
digital video standard, and the corresponding anamorphic widescreen formats. The
720 by 480 pixel raster uses thin pixels on a 4:3 aspect ratio display and fat pixels on a 16:9 display.
The popularity of viewing video on mobile phones has led to the growth of
vertical video
A vertical video is a video created either by a camera or computer that is intended for viewing in portrait mode, producing an image that is taller than it is wide. It thus sits in opposition to the multiple horizontal formats normalised by ci ...
. Mary Meeker, a partner at Silicon Valley venture capital firm
Kleiner Perkins Caufield & Byers
Kleiner Perkins, formerly Kleiner Perkins Caufield & Byers (KPCB), is an American venture capital firm which specializes in investing in incubation, early stage and growth companies. Since its founding in 1972, the firm has backed entrepreneurs ...
, highlighted the growth of vertical video viewing in her 2015 Internet Trends Report growing from 5% of video viewing in 2010 to 29% in 2015. Vertical video ads like
Snapchat
Snapchat is an American multimedia instant messaging app and service developed by Snap Inc., originally Snapchat Inc. One of the principal features of Snapchat is that pictures and messages are usually only available for a short time before the ...
’s are watched in their entirety nine times more frequently than landscape video ads.
Color model and depth
The
color model
A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components. When this model is associated with a precise description of how the compon ...
the video color representation and maps encoded color values to visible colors reproduced by the system. There are several such representations in common use: typically
YIQ
YIQ is the color space used by the analog NTSC color TV system, employed mainly in North and Central America, and Japan.
''I'' stands for ''in-phase'', while ''Q'' stands for ''quadrature'', referring to the components used in quadrature amplitud ...
is used in NTSC television,
YUV
YUV is a color model typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, compared to a "direct" RGB-representation. H ...
is used in PAL television,
YDbDr
YDbDr, sometimes written YDBDR, is the colour space used in the SECAM analog terrestrial colour television broadcasting standard (adopted in France and some countries of the former Eastern Bloc) and PAL-N (adopted in Argentina, Paraguay and Urugu ...
is used by SECAM television and
YCbCr
YCbCr, Y′CbCr, or Y Pb/Cb Pr/Cr, also written as YCBCR or Y′CBCR, is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-diffe ...
is used for digital video.
The number of distinct colors a pixel can represent depends on
color depth
Color depth or colour depth (see spelling differences), also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring to ...
expressed in the number of bits per pixel. A common way to reduce the amount of data required in digital video is by
chroma subsampling
Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance.
It is us ...
(e.g., 4:4:4, 4:2:2, etc.). Because the human eye is less sensitive to details in color than brightness, the luminance data for all pixels is maintained, while the chrominance data is averaged for a number of pixels in a block and that same value is used for all of them. For example, this results in a 50% reduction in chrominance data using 2-pixel blocks (4:2:2) or 75% using 4-pixel blocks (4:2:0). This process does not reduce the number of possible color values that can be displayed, but it reduces the number of distinct points at which the color changes.
Video quality
Video quality
Video quality is a characteristic of a video passed through a video transmission or processing system that describes perceived video degradation (typically, compared to the original video). Video processing systems may introduce some amount of dist ...
can be measured with formal metrics like
Peak signal-to-noise ratio
Peak signal-to-noise ratio (PSNR) is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic ...
(PSNR) or through
subjective video quality
Subjective video quality is video quality as experienced by humans. It is concerned with how video is perceived by a viewer (also called "observer" or "subject") and designates their opinion on a particular video sequence. It is related to the fiel ...
assessment using expert observation. Many subjective video quality methods are described in the
ITU-T
The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Commu ...
recommendation
BT.500. One of the standardized methods is the ''Double Stimulus Impairment Scale'' (DSIS). In DSIS, each expert views an ''unimpaired'' reference video followed by an ''impaired'' version of the same video. The expert then rates the ''impaired'' video using a scale ranging from "impairments are imperceptible" to "impairments are very annoying".
Video compression method (digital only)
Uncompressed video
Uncompressed video is digital video that either has never been compressed or was generated by decompressing previously compressed digital video. It is commonly used by video cameras, video monitors, video recording devices (including general-pur ...
delivers maximum quality, but at a very high
data rate. A variety of methods are used to compress video streams, with the most effective ones using a
group of pictures
In video coding, a group of pictures, or GOP structure, specifies the order in which intra- and inter-frames are arranged. The GOP is a collection of successive pictures within a coded video stream. Each coded video stream consists of successive ...
(GOP) to reduce spatial and temporal
redundancy. Broadly speaking, spatial redundancy is reduced by registering differences between parts of a single frame; this task is known as ''
intraframe
Intra-frame coding is a data compression technique used within a video frame, enabling smaller file sizes and lower bitrates, with little or no loss in quality. Since neighboring pixels within an image are often very similar, rather than storing ...
compression'' and is closely related to
image compression
Image compression is a type of data compression applied to digital images, to reduce their cost for storage or transmission. Algorithms may take advantage of visual perception and the statistical properties of image data to provide superior r ...
. Likewise, temporal redundancy can be reduced by registering differences between frames; this task is known as ''
interframe compression'', including
motion compensation
Motion compensation in computing, is an algorithmic technique used to predict a frame in a video, given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video d ...
and other techniques. The most common modern compression standards are
MPEG-2
MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic video coding format, coding of moving pictures and associated audio information". It describes a combination of Lossy compression, lossy video compression and ...
, used for
DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
,
Blu-ray
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of sto ...
and
satellite television
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
, and
MPEG-4
MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related tec ...
, used for
AVCHD
AVCHD (Advanced Video Coding High Definition) is a file-based format for the digital recording and playback of high-definition video. It is H.264 and Dolby AC-3 packaged into the MPEG transport stream, with a set of constraints designed around t ...
, Mobile phones (3GP) and Internet.
Stereoscopic
Stereoscopic
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the depth perception, illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any stere ...
video for
3d film
3D films are motion pictures made to give an illusion of three-dimensional solidity, usually with the help of special glasses worn by viewers. They have existed in some form since 1915, but had been largely relegated to a niche in the motion pict ...
and other applications can be displayed using several different methods:
* Two channels: a right channel for the right eye and a left channel for the left eye. Both channels may be viewed simultaneously by using
light-polarizing filters 90 degrees off-axis from each other on two video projectors. These separately polarized channels are viewed wearing eyeglasses with matching polarization filters.
*
Anaglyph 3D
Anaglyph 3D is the stereoscopic 3D effect achieved by means of encoding each eye's image using filters of different (usually chromatically opposite) colors, typically red and cyan. Anaglyph 3D images contain two differently filtered colored ...
where one channel is overlaid with two color-coded layers. This left and right layer technique is occasionally used for network broadcast or recent anaglyph releases of 3D movies on DVD. Simple red/cyan plastic glasses provide the means to view the images discretely to form a stereoscopic view of the content.
* One channel with alternating left and right frames for the corresponding eye, using
LCD shutter glasses
An active shutter 3D system (a.k.a. alternate frame sequencing, alternate image, AI, alternating field, field sequential or eclipse method) is a technique of displaying stereoscopic 3D images. It works by only presenting the image intended for th ...
that synchronize to the video to alternately block the image to each eye, so the appropriate eye sees the correct frame. This method is most common in computer
virtual reality
Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), educ ...
applications such as in a
Cave Automatic Virtual Environment, but reduces effective video framerate by a factor of two.
Formats
Different layers of video transmission and storage each provide their own set of formats to choose from.
For transmission, there is a physical connector and signal protocol (see
List of video connectors
This is a list of physical RF and video connectors and related video signal standards.
By signal standard
Physical connectors
D-subminiature family
DVI-related
DIN/Mini-DIN connector, Mini-DIN
Others
See also
*Computer display stan ...
). A given physical link can carry certain
display standards that specify a particular refresh rate,
display resolution
The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is ...
, and
color space
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital represent ...
.
Many analog and digital
recording format
A recording format is a format for encoding data for storage on a storage medium. The format can be container information such as sectors on a disk, or user/audience information (content) such as analog stereo audio. Multiple levels of encodin ...
s are in use, and digital
video clip
Video clips refer to mostly short videos, most of the time called memes, which are short videos of silly jokes and funny clips, most of the time coming from movies or any entertainment videos such as YouTube. The term is also used more loosely to ...
s can also be stored on a
computer file system
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
as files, which have their own formats. In addition to the physical format used by the
data storage device
Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are conside ...
or transmission medium, the stream of ones and zeros that is sent must be in a particular digital
video coding format
A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital video content (such as in a data file or bitstream). It typically uses a standardized video compression algo ...
, of which a number are available.
Analog video
Analog video is a video signal represented by one or more
analog signal
An analog signal or analogue signal (see spelling differences) is any continuous signal representing some other quantity, i.e., ''analogous'' to another quantity. For example, in an analog audio signal, the instantaneous signal voltage varies c ...
s. Analog color video signals include
luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...
, brightness (Y) and
chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying luma signal (or Y' for short). Chrominance is usually represente ...
(C). When combined into one channel, as is the case, among others with
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
,
PAL
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
and
SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
it is called
composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
. Analog video may be carried in separate channels, as in two channel
S-Video
S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channe ...
(YC) and multi-channel
component video
Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compon ...
formats.
Analog video is used in both consumer and professional
television production
A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite, or cable, excluding breaking news, advertisements, or trailers that are typically placed betw ...
applications.
Composite-video-cable.jpg, Composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...
(single channel RCA)
Close-up_of_S-video_female_connector.jpg, S-Video
S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channe ...
(2-channel YC)
Component-cables.jpg, Component video
Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compon ...
(3-channel YPbPr
YPbPr or Y'PbPr, also written as , is a color space used in video electronics, in particular in reference to component video cables. YPBPR is gamma corrected YCBCR color space (it is not analog YUV that was used for analog TV, though component ...
)
SCART_20050724_002.jpg, SCART
SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard and associated 21- ...
Vga-cable.jpg, VGA
Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the PC industry within three years. The term can no ...
3.5mm.jpg, TRRS
D4_video_connector.jpg, D-Terminal
Digital video
Digital video
Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...
signal formats have been adopted, including
serial digital interface (SDI),
Digital Visual Interface
Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a co ...
(DVI),
High-Definition Multimedia Interface
High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
(HDMI) and
DisplayPort
DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...
Interface.
BNC_connector_%28male%29.jpg, Serial digital interface (SDI)
Dvi-cable.jpg, Digital Visual Interface
Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a co ...
(DVI)
HDMI-Connector.jpg, HDMI
High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
Displayport-cable.jpg, DisplayPort
DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...
Transport medium
Video can be transmitted or transported in a variety of ways including wireless
terrestrial television
Terrestrial television or over-the-air television (OTA) is a type of television broadcasting in which the signal transmission occurs via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an ant ...
as an analog or digital signal, coaxial cable in a closed-circuit system as an analog signal. Broadcast or studio cameras use a single or dual coaxial cable system using
serial digital interface (SDI). See
List of video connectors
This is a list of physical RF and video connectors and related video signal standards.
By signal standard
Physical connectors
D-subminiature family
DVI-related
DIN/Mini-DIN connector, Mini-DIN
Others
See also
*Computer display stan ...
for information about physical connectors and related signal standards.
Video may be transported over networks and other shared digital communications links using, for instance,
MPEG transport stream
MPEG transport stream (MPEG-TS, MTS) or simply transport stream (TS) is a standard digital container format for transmission and storage of audio, video, and Program and System Information Protocol (PSIP) data. It is used in broadcast systems ...
,
SMPTE 2022
SMPTE 2022 is a standard from the Society of Motion Picture and Television Engineers (SMPTE) that describes how to send digital video over an IP network. Video formats supported include MPEG-2 and serial digital interface The standard was introduc ...
and
SMPTE 2110
SMPTE 2110 is a suite of standards from the Society of Motion Picture and Television Engineers (SMPTE) that describes how to send digital media over an IP network.
SMPTE 2110 is intended to be used within broadcast production and distribution fac ...
.
Display standards
Digital television
Digital television
Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advanc ...
broadcasts use the
MPEG-2
MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic video coding format, coding of moving pictures and associated audio information". It describes a combination of Lossy compression, lossy video compression and ...
and other
video coding format
A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital video content (such as in a data file or bitstream). It typically uses a standardized video compression algo ...
s and include:
*
ATSC
Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
– United States,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
,
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
,
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
*
Digital Video Broadcasting
Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) ...
(DVB) –
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
*
ISDB
Integrated Services Digital Broadcasting (ISDB; Japanese language, Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio.
ISDB supersedes both the NTSC-J analog telev ...
–
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
**
ISDB-Tb
ISDB-T International, or SBTVD, short for Sistema Brasileiro de Televisão Digital ( en, Brazilian Digital Television System), is a technical standard for digital television broadcast used in Brazil, Argentina, Peru, Botswana, Chile, Honduras, Ve ...
– uses the MPEG-4 video coding format –
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
*
Digital Multimedia Broadcasting (DMB) –
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
Analog television
Analog television
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, instantaneous phase and frequency, ...
broadcast standards include:
* Field-sequential color system (FCS) – US, Russia; obsolete
*
Multiplexed Analogue Components
Multiplexed Analogue Components (MAC) was an analog television standard where luminance and chrominance components were transmitted separately. This was an evolution from older color TV systems (such as PAL or SECAM) where there was interferen ...
(MAC) – Europe; obsolete
*
Multiple sub-Nyquist sampling encoding
MUSE (Multiple sub-Nyquist Sampling Encoding), commercially known as Hi-Vision (a contraction of HIgh-definition teleVISION) was a Japanese analog HDTV system, with design efforts going back to 1979.
It used dot-interlacing and digital video co ...
(MUSE) – Japan
*
NTSC
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
–
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
**
EDTV-II "Clear-Vision" - NTSC extension, Japan
*
PAL
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
–
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
,
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
,
Oceania
Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
**
PAL-M
PAL-M is the analogue TV system used in Brazil since 19 February 1972. At that time, Brazil was the first South American country to broadcast in colour. Colour TV broadcast began on 19 February 1972, when the TV networks Globo and Bandeirantes t ...
– PAL variation,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
**
PAL-N
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
– PAL variation,
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
,
Paraguay
Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...
and
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
**
PALplus
PALplus (or ''PAL+'') is an analogue television broadcasting system aimed to improve and enhance the PAL format by allowing 16:9 (or 1.77:1) aspect ratio broadcasts, while remaining compatible with existing television receivers, defined by ITU re ...
– PAL extension,
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
*
RS-343
Here is a list of American Electronic Industries Alliance (EIA) Standards.
The EIA ceased operations on February 11, 2011, but the former sectors continue to serve the constituencies of EIA. EIA designated ECA to continue to develop standards f ...
(military)
*
SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''color sequential with memory''), is an analog color television system that was used in France, some parts of Europe and Africa, and Russia. It was one of th ...
–
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, former
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
,
Central Africa
Central Africa is a subregion of the African continent comprising various countries according to different definitions. Angola, Burundi, the Central African Republic, Chad, the Democratic Republic of the Congo, the Republic of the Congo, ...
*
CCIR System A
CCIR System A was the 405-line analog broadcast television system adopted in the UK and Ireland. System A service started in 1936 and was discontinued in 1985.
Specifications
Some of the important specs are listed below.
A frame is the t ...
*
CCIR System B
CCIR System B (originally known as the "Gerber Standard") was the 625-line VHF analog broadcast television system which at its peak was the system used in most countries. It's usually associated with CCIR System G for UHF broadcasts.
It is most ...
*
CCIR System G
CCIR System G is an analog broadcast television system used in many countries. There are several systems in use and letter G is assigned for the European UHF system which is also used in the majority of Asian and African countries. (However some ...
*
CCIR System H
CCIR System H is an analog broadcast television system primarily used in Belgium, the Balkans and Malta on the UHF bands.
Specifications
Some of the important specs are listed below.Reference Data for Radio Engineers, ITT Howard W.Sams Co., N ...
*
CCIR System I
CCIR System I is an analogue broadcast television system. It was first used in the Republic of Ireland starting in 1962 as the 625-line broadcasting standard to be used on VHF Band I and Band III, sharing Band III with 405-line System A signals ...
*
CCIR System M
An analog video format consists of more information than the visible content of the frame. Preceding and following the image are lines and pixels containing metadata and synchronization information. This surrounding margin is known as a ''blanking interval'' or ''blanking region''; the horizontal and vertical
front porch and back porch are the building blocks of the blanking interval.
Computer displays
Computer display standard
Computer display standards are a combination of aspect ratio, display size, display resolution, color depth, and refresh rate. They are associated with specific expansion cards, video connectors and monitors.
History
Various computer displa ...
s specify a combination of aspect ratio, display size, display resolution, color depth, and refresh rate. A
list of common resolutions
This article lists computer monitor screen resolutions that are defined by standards or in common use. Most of them use certain preferred numbers.
Computer graphics
; Pixel aspect ratio (PAR): The horizontal to vertical ratio of each pixel.
...
is available.
Recording
Early television was almost exclusively a live medium with some programs recorded to film for distribution of historical purposes using
Kinescope
Kinescope , shortened to kine , also known as telerecording in Britain, is a recording of a television program on motion picture film, directly through a lens focused on the screen of a video monitor. The process was pioneered during the 1940 ...
. The analog
video tape recorder
A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were use ...
was commercially introduced in 1951. The following list is in rough chronological order. All formats listed were sold to and used by broadcasters, video producers or consumers; or were important historically.
*
2" Quadruplex videotape (
Ampex
Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name AMPEX is a portmanteau, created by its founder, which stands for Alexander M. Poniatoff Excellence.AbramsoThe History ...
1956)
*
VERA (
BBC #REDIRECT BBC #REDIRECT BBC
Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
...
experimental format ca. 1958)
*
) (1994)
Digital video tape recorders offered improved quality compared to analog recorders.
Optical storage mediums offered an alternative, especially in consumer applications, to bulky tape formats.
. In the context of video compression, ''