Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical Videography refers to the process of capturing moving Images on Electronic media (e In TV and movies, a scene is a part of the action in a single location
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History
Video technology was first developed for cathode ray tube television systems, but several new technologies for video display devices have since been invented. Technology is a broad concept that deals with a Species ' usage and knowledge of Tools and Crafts and how it affects a species' ability to control and adapt The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Standards for television sets and computer monitors have tended to evolve independently, but advances in computer performance and digital television broadcasting and recording are producing some convergence. A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by
Computers can now display television and film-style video clips and streaming media, encouraged by increased processor speed, storage capacity, and broadband access to the Internet. This page is about the visual medium for the Thai film see Video Clip (2007 film. Streaming multimedia is Multimedia that is constantly received by and normally presented to an end-user while it is being delivered by a streaming provider (the The term broadband can have different meanings in different contexts The Internet is a global system of interconnected Computer networks General-purpose computing hardware can now be used to capture, store, edit, and transmit television and movie content, as opposed to older dedicated analog technologies.
Description of video
The term video (from Latin: "I see") commonly refers to several storage formats for moving eye pictures: digital video formats, including DVD, QuickTime, and MPEG-4; and analog videotapes, including VHS and Betamax. NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system The term digital signal is used to refer to more than one concept DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is QuickTime is a Multimedia framework developed by Apple Inc, capable of handling various formats of Digital video, Media clips sound text MPEG-4 is a collection of methods defining compression of audio and visual (AV digital data An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other Videotape is a means of recording images and sound onto Magnetic tape as opposed to movie film. ---- Betamax is a home Videocassette tape recording format developed by Sony, and released on May 10, 1975. Video can be recorded and transmitted in various physical media: in magnetic tape when recorded as PAL or NTSC electric signals by video cameras, or in MPEG-4 or DV digital media when recorded by digital cameras. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico A video camera is a Camera used for electronic Motion picture acquisition initially developed by the Television industry but now common in other applications MPEG-4 is a collection of methods defining compression of audio and visual (AV digital data Digital Video (DV is a Digital video format created by Sony JVC Panasonic and other video camera procuers and launched in 1995 and in its smaller tape Form factor Many compact digital still cameras can record Sound and moving Video as well as still Photograph.
Quality of video essentially depends on the capturing method and storage used. Video quality is a characteristic of a Video passed through a video transmission/processing system a formal or informal measure of perceived video degradation (typically compared Digital television (DTV) is a relatively recent format with higher quality than earlier television formats and has become a standard for television video. Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by (See List of digital television deployments by country. This is a list of Digital television deployments by country, which summarises the process and progress of transition from analogue to digital broadcasting )
3D-video, digital video in three dimensions, premiered at the end of 20th century. See also [[stereoscopy]] In film the term 3-D (or 3D) is used to describe any visual presentation system that attempts to maintain or recreate moving images Six or eight cameras with realtime depth measurement are typically used to capture 3D-video streams. The format of 3D-video is fixed in MPEG-4 Part 16 Animation Framework eXtension (AFX). MPEG-4 is a collection of methods defining compression of audio and visual (AV digital data
In the UK, Australia, The Netherlands, Finland, Hungary and New Zealand, the term video is often used informally to refer to both Videocassette recorders and video cassettes; the meaning is normally clear from the context. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located For a topic outline on this subject see List of basic Australia topics. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands Finland, officially the Republic of Finland ( is a Nordic country situated in the Fennoscandian region of northern Europe. Hungary (Magyarország 'mɔɟɔrorsaːg) officially in English the Republic of Hungary ( Magyar Köztársaság, literally Magyar (Hungarian Republic New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island PLEASE BEAR IN MIND THAT THIS IS A GENERAL ARTICLE ABOUT VCRs/VIDEOCASSETTE RECORDERS Videotape is a means of recording images and sound onto Magnetic tape as opposed to movie film.
Characteristics of video streams
Number of frames per second
Frame rate, 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. Frame rate, or frame frequency, is the measurement of the Frequency (rate at which an imaging device produces unique consecutive images called frames The PAL (Europe, Asia, Australia, etc. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world ) and SECAM (France, Russia, parts of Africa etc. SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system ) standards specify 25 frame/s, while NTSC (USA, Canada, Japan, etc. NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico ) specifies 29. 97 frame/s. Film is shot at the slower frame rate of 24frame/s, which complicates slightly the process of transferring a cinematic motion picture to video. The minimum frame rate to achieve the illusion of a moving image is about fifteen frames per second.
Interlacing
Video can be interlaced or progressive. For the method of incrementally displaying Raster graphics, see Interlace (bitmaps. Progressive or noninterlaced scanning is a method for displaying storing or transmitting Moving images in which all the lines of each frame are drawn in Interlacing was invented as a way to achieve good visual quality within the limitations of a narrow bandwidth. The horizontal scan lines of each interlaced frame are numbered consecutively and partitioned into two fields: the odd field (upper field) consisting of the odd-numbered lines and the even field (lower field) consisting of the even-numbered lines. 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 specified as 576i50, where 576 indicates the vertical line resolution, i indicates interlacing, and 50 indicates 50 fields (half-frames) per second.
In progressive scan systems, each refresh period updates all of the scan lines. The result is a higher perceived resolution and a lack of various artifacts that can make parts of a stationary picture appear to be moving or flashing.
A procedure known as deinterlacing can be used for converting an interlaced stream, such as analog, DVD, or satellite, to be processed by progressive scan devices, such as TFT TV-sets, projectors, and plasma panels. Deinterlacing is the process of converting Interlaced video like common Analog television signals into a non-interlaced form Liquid-crystal display televisions ( LCD TV) are Television sets that use LCD technology to produce images Deinterlacing cannot, however, produce a video quality that is equivalent to true progressive scan source material. Video quality is a characteristic of a Video passed through a video transmission/processing system a formal or informal measure of perceived video degradation (typically compared
Display resolution
The size of a video image is measured in pixels for digital video, or horizontal scan lines and vertical lines of resolution for analog video. The display resolution of a Digital television or Computer display typically refers to the number of distinct pixels in each dimension that can be displayed See also Display resolution This is a list of image resolutions sorted by the horizontal Pixel dimension in ascending numerical order In Digital imaging, a pixel ( pict ure el ement is the smallest piece of information in an image In the digital domain (e. g. DVD) standard-definition television (SDTV) is specified as 720/704/640×480i60 for NTSC and 768/720×576i50 for PAL or SECAM resolution. However in the analog domain, the number of visible scanlines remains constant (486 NTSC/576 PAL) while the horizontal measurement varies with the quality of the signal: approximately 320 pixels per scanline for VCR quality, 400 pixels for TV broadcasts, and 720 pixels for DVD sources. Aspect ratio is preserved because of non-square "pixels".
New high-definition televisions (HDTV) are capable of resolutions up to 1920×1080p60, i. High-definition television (HDTV is a Digital television Broadcasting system with higher resolution than traditional television systems (standard-definition e. 1920 pixels per scan line by 1080 scan lines, progressive, at 60 frames per second.
Video resolution for 3D-video is measured in voxels (volume picture element, representing a value in three dimensional space). A voxel (a Portmanteau of the words Volumetric and Pixel) is a volume element representing a value on a Regular grid in For example 512×512×512 voxels resolution, now used for simple 3D-video, can be displayed even on some PDAs.
Aspect ratio
Aspect ratio describes the dimensions of video screens and video picture elements. The aspect ratio of an Image is its width divided by its height All popular video formats are rectilinear, and so can be described by a ratio between width and height. The screen aspect ratio of 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 "Academy standard") is around 2. 37:1.
Pixels on computer monitors are usually square, but pixels used in digital video often have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video standard, and the corresponding anamorphic widescreen formats. Digital video is a type of Video recording system that works by using a Digital rather than an analog video signal ITU-R Recommendation BT601, more commonly know by the abbreviations Rec Therefore, an NTSC DV image which is 720 pixels by 480 pixels is displayed with the aspect ratio of 4:3 (which is the traditional television standard) if the pixels are thin and displayed with the aspect ratio of 16:9 (which is the anamorphic widescreen format) if the pixels are fat.
Color space and bits per pixel
Color model name describes the video color representation. YIQ was used in NTSC television. YIQ is the Color space used by the NTSC color TV system employed mainly in North and Central America, and Japan. It corresponds closely to the YUV scheme used in NTSC and PAL television and the YDbDr scheme used by SECAM television. YDbDr is the Colour space used in the SÉCAM colour Television broadcasting standard which is used in France and some countries of the former
The number of distinct colours that can be represented by a pixel depends on the number of bits per pixel (bpp). A common way to reduce the number of bits per pixel in digital video is by chroma subsampling (e. Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information g. 4:4:4, 4:2:2, 4:2:0). Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information
Video quality
Video quality can be measured with formal metrics like PSNR or with subjective video quality using expert observation. Video quality is a characteristic of a Video passed through a video transmission/processing system a formal or informal measure of perceived video degradation (typically compared The phrase peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power Subjective video quality is a subjective characteristic of Video quality.
The subjective video quality of a video processing system may be evaluated as follows:
- Choose the video sequences (the SRC) to use for testing.
- Choose the settings of the system to evaluate (the HRC).
- Choose a test method for how to present video sequences to experts and to collect their ratings. Scientific method refers to bodies of Techniques for investigating phenomena
- Invite a sufficient number of experts, preferably not fewer than 15.
- Carry out testing.
- Calculate the average marks for each HRC based on the experts' ratings.
Many subjective video quality methods are described in the ITU-T recommendation BT. Subjective video quality is a subjective characteristic of Video quality. The ITU Telecommunication Standardization Sector ( ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication 500. One of the standardized method 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)
A wide variety of methods are used to compress video streams. Video compression refers to reducing the quantity of Data used to represent video images and is a straightforward combination of Image compression and Motion Video compression refers to reducing the quantity of Data used to represent video images and is a straightforward combination of Image compression and Motion Video data contains spatial and temporal redundancy, making uncompressed video streams extremely inefficient. Redundancy in Information theory is the number of bits used to transmit a message minus the number of bits of actual information in the message Broadly speaking, spatial redundancy is reduced by registering differences between parts of a single frame; this task is known as intraframe compression and is closely related to image compression. Image compression is the application of Data compression on Digital images In effect the objective is to reduce redundancy of the image data in order to be able to Likewise, temporal redundancy can be reduced by registering differences between frames; this task is known as interframe compression, including motion compensation and other techniques. One method used by various video formats to reduce file size is motion compensation. The most common modern standards are MPEG-2, used for DVD and satellite television, and MPEG-4, used for home video. MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information" DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is Satellite television is Television delivered by the means of Communications satellites as compared to conventional Terrestrial television and Cable MPEG-4 is a collection of methods defining compression of audio and visual (AV digital data
Bit rate (digital only)
Bit rate is a measure of the rate of information content in a video stream. In Telecommunications and Computing, bitrate (sometimes written bit rate, data rate or as a Variable R or f b It is quantified using the bit per second (bit/s or bps) unit or Megabits per second (Mbit/s). A higher bit rate allows better video quality. Video quality is a characteristic of a Video passed through a video transmission/processing system a formal or informal measure of perceived video degradation (typically compared For example VideoCD, with a bit rate of about 1 Mbit/s, is lower quality than DVD, with a bit rate of about 5 Mbit/s. HDTV has a still higher quality, with a bit rate of about 20 Mbit/s.
Variable bit rate (VBR) is a strategy to maximize the visual video quality and minimize the bit rate. Variable bitrate ( VBR) or less commonly variable bit rate, is a term used in Telecommunications and Computing that relates to the On fast motion scenes, a variable bit rate uses more bits than it does on slow motion scenes of similar duration yet achieves a consistent visual quality. For real-time and non-buffered video streaming when the available bandwidth is fixed, e. g. in videoconferencing delivered on channels of fixed bandwidth, a constant bit rate (CBR) must be used. Constant bitrate (CBR is a term used in Telecommunications, relating to the Quality of service.
Stereoscopic
Stereoscopic video requires either two channels — a right channel for the right eye and a left channel for the left eye or two overlayed 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. * New HD DVD and Blu-ray Discs will greatly improve the 3D effect, in color coded stereo programs. not insert the publicly disclosed HD DVD key into this article for the time being The first commercially available HD players were expected to debut at the 2006 NAB Show in Las Vegas in April. National Association of Broadcasters (NAB is a trade association representing the interests of for-profit over-the-air radio and television broadcasters in the United States See articles Stereoscopy and 3-D- Max film. Stereoscopy, stereoscopic imaging or 3-D (three-dimensional imaging is any technique capable of recording three-dimensional visual
Video formats
There are different layers of video transmission and storage, each with its own set of formats to choose from.
For transmission, there is a physical connector and signal protocol ("video connection standard" below). A given physical link can carry certain "display standards" which specify a particular refresh rate, display resolution, and color space. The display resolution of a Digital television or Computer display typically refers to the number of distinct pixels in each dimension that can be displayed 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 There are a number of analog and digital tape formats, though digital video files can also be stored on a computer file system which have their own formats. In Computing, a file system (often also written as filesystem) is a method for storing and organizing Computer files and the data they contain to make In addition to the physical format used by the storage or transmission medium, the stream of ones and zeros that is sent must be in a particular digital video "encoding", of which a number are available.
Video connectors, cables, and signal standards
- See List of video connectors for information about physical connectors and related signal standards. This is a list of physical video connectors and related video signal standards.
Video display standards
Digital television
New formats for digital television broadcasts use the MPEG-2 video codec and include:
- ATSC - USA, Canada, etc. Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information" A video Codec is a device or Software that enables Video compression and/or decompression for digital video ; a DVB video standard
- Digital Video Broadcasting (DVB) - European
- Integrated Services Digital Broadcasting (ISDB) - Japanese; also a DVB video standard
Analog television
Analog television broadcast standards include:
- Multiplexed Analogue Components (MAC) - Europe, obsolete
- Multiple sub-nyquist sampling Encoding (MUSE) - Japan, analog HDTV
- NTSC - USA, Canada, Japan, etc. For the chemical compound see Divinylbenzene. Digital Video Broadcasting ( DVB) is a suite of internationally accepted For the chemical compound see Divinylbenzene. Digital Video Broadcasting ( DVB) is a suite of internationally accepted Integrated Services Digital Broadcasting (ISDB is a Japanese standard for Digital television (DTV and Digital radio used by the country's radio For the chemical compound see Divinylbenzene. Digital Video Broadcasting ( DVB) is a suite of internationally accepted Analog (or analogue) television encodes Television picture and sound information and transmits it as an Analog signal: one in which the Multiplexed Analogue Components (MAC was a Satellite television transmission standard originally proposed for use on a Europe-wide terrestrial HDTV system although it was MUSE ( Multiple Sub-nyquist Sampling Encoding System also known as Hi-Vision for marketing purposes was an early high-definition analog television standard developed NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico
- PAL - Europe, Asia, Australia, etc. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world
- SECAM - France, ex-USSR, Central Africa
- Field-sequential color system - USA, Russia; obsolete
- RS-343 (military)
An analog video format consists of more information than the visible content of the frame. |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system A field-sequential color system is a color Television system in which the primary color information is transmitted in successive images and which relies on the human vision Here is a list of Electronic Industries Alliance (EIA Standards EIA-232 RS-232 electrical characteristics single-ended voltage digital interface circuit Preceding and following the image are lines and pixels containing synchronization information or a time delay. 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. Front Porch Inc provides services to Internet Service Providers. Back porch refers to the portion in each scan line of a video signal between the end (rising edge of the horizontal sync pulse and the start of active video
Many countries are planning a digital switchover to cease using these analog formats via terrestrial television broadcast. Terrestrial television is a term which refers to modes of television broadcasting which do not involve satellite transmission However, analog television sets expecting these older standards as input will be able to display standard definition digital signals if coupled with a converter box.
Computer displays
See Computer display standard for a list of standards used for computer monitors and comparison with those used for television. Various computer display standards or display modes have been used in the history of the Personal computer.
Analog tape formats
- Ampex
- VERA (BBC experimental format ca. Ampex ( is an American electronics company founded in 1944 by Alexander M VERA (Vision Electronic Recording Apparatus was an early Videotape format developed by the BBC beginning in 1952 1958)
- Philips videotape recorder EL3400 1" helical scan ca. 1963
- U-matic (Sony)
- Betamax (Sony)
- Betacam
- Betacam SP
- 2" Quadruplex videotape (Ampex)
- 1" Type C videotape (Ampex and Sony)
- 1" Type B video tape (Bosch)
- VCR, VCR-LP, SVR
- VHS (JVC)
- S-VHS (JVC)
- VHS-C (JVC)
- Video 2000 (Philips)
- Video8
- Video Hi8
Digital tape formats
- D1 (Sony)
- D2 (Sony)
- D3
- D5 HD
- Digital Betacam (Sony)
- Betacam IMX (Sony)
- HDV
- ProHD (JVC)
- D-VHS (JVC)
- DV
- MiniDV
- MicroMV
- Digital8 (Sony)
Optical disc storage formats
- DVD (was Super Density Disc, DVD Forum)
- Laserdisc (old, MCA and Philips)
- Blu-ray Disc (Sony)
- Enhanced Versatile Disc (EVD, Chinese government-sponsored)
- HD DVD (NEC and Toshiba)
Digital encoding formats
- CCIR 601 (ITU-T)
- M-JPEG (ISO)
- MPEG-1 (ISO)
- MPEG-2 (ITU-T + ISO)
- MPEG-4 (ISO)
- H.261 (ITU-T)
- H.263 (ITU-T)
- H.264/MPEG-4 AVC (ITU-T + ISO)
- VC-1 (SMPTE)
- Ogg-Theora
- See also: Video codec
- See also: List of codecs
See also
- Video format
- Video usage
- Video screen recording
External links
- Video as Media Production at the Open Directory Project
- Video as Arts at the Open Directory Project
- Programmer's Guide to Video Systems: in-depth technical info on 480i,576i,1080i,720p,etc.
Dictionary
video
-noun
- Television, television show, movie.
- motion picture stored on VHS or some other format.
- (dated) VHS.
-verb
- To record using video equipment
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