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all photos are from flickr, for more information about them, click the *
'''Video''' is the technology of electronically capturing, scenes in motion. HistoryVideo technology was first developed for cathode ray tube television systems, but several new technologies for video display devices have since been invented. 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.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. 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[[Image:NTSC-PAL-SECAM.svg|thumb|300px|Analog video standards worldwide ]]The term ''video'' (from Latin: "I see") commonly refers to several storage formats for moving eye pictures: digital video formats, including analog videotapes, including VHS and Betamax. 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.Quality of video essentially depends on the capturing method and storage used. Digital television ''(DTV)'' is a relatively recent format with higher quality than earlier television formats and has become a standard for television video. ''(See List of digital television deployments by country.)''''3D-video'', digital video in three dimensions, premiered at the end of 20th century. 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).In the UK, video cassettes; the meaning is normally clear from the context.Characteristics of video streamsNumber of frames per secondVideo can be progressive. 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 TFT TV-sets, projectors, and plasma panels. Deinterlacing cannot, however, produce a video quality that is equivalent to true progressive scan source material.Display resolutionthumb|240px|List of common resolutions|Common computer and TV display resolutions. The size of a video image is measured in SDTV) is specified as ''720/704/640أ—480i60'' for NTSC and ''768/720أ—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 ''1920أ—1080p60'', i.e. 1920 pixels per scan line by 1080 scan lines, progressive, at 60 frames per second.Video resolution for 3D-video is measured in PDAs.Aspect ratiothumbnail|250px|Comparison of common cinematography and traditional (green) aspect ratios.">television">(green) aspect ratios. 120px|thumb|left|Many arcade games use 3:4 portrait mode to efficiently utilize the entire display area. Aspect ratio describes the dimensions of video screens and video picture elements. 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. Ratios where the height is taller than the width are uncommon in general everyday use, but do have application in computer systems where the screen may be better suited for a vertical layout. The most common tall aspect ratio of 3:4 is referred to as ''portrait mode'' and is created by physically rotating the display device 90 degrees from the normal position. Other tall aspect ratios such as 9:16 are technically possible but rarely used. (For a more detailed discussion of this topic please refer to the page orientation article.)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. 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 pixelVideo quality can be measured with formal metrics like PSNR or with subjective video quality using expert observation.The subjective video quality of a video processing system may be evaluated as follows:
Video connectors, cables, and signal standards
=Digital television= New formats for digital television broadcasts use the MPEG-2 video codec and include:
Analog tape formats
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