Standard-definition television

Standard-definition television (SDTV or SD) is a television system which uses a resolution that is not considered to be either high or enhanced definition. The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions.

In North America, digital SDTV is broadcast in the same 4:3 aspect ratio as NTSC signals, with widescreen content being center cut.[1] However, in other parts of the world that used the PAL or SECAM color systems, standard-definition television is now usually shown with a 16:9 aspect ratio, with the transition occurring between the mid-1990s and mid-2000s depending on region. Older programs with a 4:3 aspect ratio are broadcast with a flag that switches the display to 4:3.[a]

Standards that support digital SDTV broadcast include DVB, ATSC, and ISDB. The last two were originally developed for HDTV, but are more often used for their ability to deliver multiple SD video and audio streams via multiplexing, than for using the entire bitstream for one HD channel.

SDTV refresh rates can be 24, 25, 30, 50 or 60 frames per second with a possible rate multiplier of 1000/1001 for NTSC. 50 and 60 rates are generally frame doubled versions of 25 and 30 rates for jitter issues when using non-interlaced lines.

Digital SDTV in 4:3 aspect ratio has the same appearance as regular analog TV (NTSC, PAL, SECAM) without the ghosting, snowy images and white noise. However, if the reception has interference or is poor, where the error correction cannot compensate one will encounter various other artifacts such as image freezing, stuttering or dropouts from missing intra-frames or blockiness from missing macroblocks. The audio encoding is the last to suffer loss due to the lower bandwidth requirements.

SDTV resolution by nation; due to historical reasons, different countries use either 480i or 576i as the standard-definition picture format.

Pixel aspect ratio

Television signals are transmitted in digitally encoded form, and the lines are scaled to fit SMPTE SDI bandwidth requirements, as opposed to unrestricted uses such as when lines are rendered or overlaid to a modern computer monitor and modern SMPTE implementations of HDTV. The table below summarizes pixel aspect ratios for the scaling of various kinds of SDTV video lines. Note that the actual image (be it 4:3 or 16:9) is always contained in the center 704 horizontal pixels of the digital frame, regardless of how many horizontal pixels (704 or 720) are used. In case of digital video line having 720 horizontal pixels, only the center 704 pixels contain actual 4:3 or 16:9 image, and the 8-pixel-wide stripes from either side are called nominal analogue blanking for horizontal blanking and should be discarded before displaying the image. Nominal analogue blanking should not be confused with overscan, as overscan areas are part of the actual 4:3 or 16:9 image.

Video format Display aspect ratio (DAR) Resolution Pixel aspect ratio (PAR) After horizontal scaling
480i 4:3 704×480
(horizontal blanking cropped)
10:11 640×480
720×480 (full frame) 654×480
480i 16:9 704×480
(horizontal blanking cropped)
40:33 854×480
720×480 (full frame) 872×480
576i 4:3 704×576
(horizontal blanking cropped)
12:11 768×576
720×576 (full frame) 786×576
576i 16:9 704×576
(horizontal blanking cropped)
16:11 1024×576
720×576 (full frame) 1048×576

The pixel aspect ratio is always the same for corresponding 720 and 704 pixel resolutions because the center part of a 720-pixel-wide image is equal to the corresponding 704-pixel-wide image.

For SMPTE 259M-C compliance, a SDTV broadcast image is scaled to 720 pixels wide[b] for every 480 NTSC (or 576 PAL) lines of the image with the amount of non-proportional line scaling dependent on either the display or pixel aspect ratio. The display ratio for broadcast widescreen is commonly 16:9,[c] the display ratio for a traditional or letterboxed broadcast is 4:3.[d]

An SDTV image outside the constraints of the SMPTE standards requires no non-proportional scaling with 640 pixels[e] for every line of the image. The display and pixel aspect ratio is generally not required with the line height defining the aspect. For widescreen 16:9, 360 lines define a widescreen image and for traditional 4:3, 480 lines define an image.

See also


  1. ^ Some broadcasters prefer to reduce the horizontal resolution by anamorphically scaling the video into a pillarbox.
  2. ^ Only 704 center pixels contain the image and 16 pixels are reserved for horizontal blanking. A number of broadcasters fill the whole 720 frame.
  3. ^ Pixel aspect ratio of 40:33 for anamorphic
  4. ^ Pixel aspect ratio of 10:11
  5. ^ Defined by the adopted IBM VGA standard


  1. ^ All-Digital Television Is Coming (And Sooner Than You Think!)

External links


480i is a shorthand name for the video mode used for standard-definition analog or digital television in Caribbean, Myanmar, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay and Uruguay). The 480 identifies a vertical resolution of 480 lines, and the i identifies it as an interlaced resolution. The field rate, which is 60 Hz (or 59.94 Hz when used with NTSC color), is sometimes included when identifying the video mode, i.e. 480i60; another notation, endorsed by both the International Telecommunication Union in BT.601 and SMPTE in SMPTE 259M, includes the frame rate, as in 480i/30. The other common standard, used in the other parts of the world, is 576i.

In analogue contexts, this resolution is often called "525 lines". It is mandated by CCIR Systems M and J, which are usually paired with NTSC color - which led to the "NTSC" name being often inaccurately used to refer to this video mode. Other color encodings have also been used with System M, notably PAL-M in Brazil.


576i is a standard-definition video mode originally used for broadcast television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because of its close association with the color encoding system, it is often referred to as simply PAL, PAL/SECAM or SECAM when compared to its 60 Hz (typically, see PAL-M) NTSC-color-encoded counterpart, 480i. In digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines", and the aspect ratio is usually 4:3 in analogue transmission and 16:9 in digital transmission.

The 576 identifies a vertical resolution of 576 lines, and the i identifies it as an interlaced resolution. The field rate, which is 50 Hz, is sometimes included when identifying the video mode, i.e. 576i50; another notation, endorsed by both the International Telecommunication Union in BT.601 and SMPTE in SMPTE 259M, includes the frame rate, as in 576i/25.

Its basic parameters common to both analogue and digital implementations are: 576 scan lines or vertical pixels of picture content, 25 frames (giving 50 fields) per second.

In analogue 49 additional lines without image content are added to the displayed frame of 576 lines to allow time for older cathode ray tube circuits to retrace for the next frame, giving 625 lines per frame. Digital information not to be displayed as part of the image can be transmitted in the non-displayed lines; teletext and other services and test signals are often implemented.

Analogue television signals have no pixels; they are rastered in scan lines, but along each line the signal is continuous. In digital applications, the number of pixels per line is an arbitrary choice as long as it fulfils the sampling theorem. Values above about 500 pixels per line are enough for conventional free-to-air television; DVB-T, DVD and DV allow better values such as 704 or 720.

The video format can be transported by major digital television formats, ATSC, DVB and ISDB, and on DVD, and it supports aspect ratios of standard 4:3 and anamorphic 16:9.

Aspect ratio

The aspect ratio of a geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side – the ratio of width to height, when the rectangle is oriented as a "landscape".

The aspect ratio is most often expressed as two integer numbers separated by a colon (x:y), less commonly as a simple or decimal fraction. The values x and y do not represent actual widths and heights but, rather, the proportion between width and height. As an example, 8:5, 16:10, 1.6:1, ​8⁄5 and 1.6 are all ways of representing the same aspect ratio.

In objects of more than two dimensions, such as hyperrectangles, the aspect ratio can still be defined as the ratio of the longest side to the shortest side.

Bell TV

Bell TV (French: Bell Télé; formerly known as Bell ExpressVu, Dish Network Canada, ExpressVu Dish Network, and now sometimes known as Bell Satellite TV to distinguish the service from Bell's IPTV Fibe TV service), is the division of BCE Inc. that provides satellite television service across Canada. It launched on September 10, 1997 and as of 2004 it has been providing "Bell TV for Condos", a VDSL service provided to select multidwelling units (condominiums and apartments) in Montreal, Ottawa and Toronto. Bell TV provides over 500 digital video and 100 HD and audio channels to, as of May 2010, over 1.8 million subscribers. Its major competitors include satellite service Shaw Direct, as well as various cable and communications companies across Canada, such as Rogers Cable, EastLink, Shaw Communications, Vidéotron and Cogeco.

Bell TV services are also repackaged and resold by Telus as Telus Satellite TV, in areas where the latter company's Optik IPTV services are unavailable.

Composite video

Composite video is an analog video transmission that carries standard definition video typically at 480i or 576i resolution as a single channel. Video information is encoded on one channel, unlike the higher-quality S-video (two channels) and the even higher-quality component video (three or more channels). In all of these video formats, audio is carried on a separate connection.

Composite video is also known by the initials CVBS for composite video baseband signal or color, video, blanking and sync, or is simply referred to as SD video for the standard-definition television signal it conveys.

There are three dominant variants of composite video: NTSC, PAL, and SECAM.

Enhanced-definition television

Enhanced-definition television, or extended-definition television (EDTV) is an American Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).

The term refers to devices capable of displaying 480-line or 576-line signals in progressive scan, commonly referred to as 480p (NTSC-HQ) and 576p (PAL) respectively, as opposed to interlaced scanning, commonly referred to as 480i (NTSC) or 576i (PAL). High-motion is optional for EDTV.In other countries definitions may vary.

Freeview (UK)

Freeview is the United Kingdom's digital terrestrial television platform. It is operated by DTV Services Ltd, a joint venture between the BBC, ITV, Channel 4, Sky and transmitter operator Arqiva. It was launched in 2002, taking over the licence from ITV Digital which collapsed that year. The service provides consumer access via an aerial to the six DTT multiplexes covering the United Kingdom. In April 2014 it had some 60 DVB-T TV channels, 26 digital radio channels, 10 HD channels, six text services, 11 streamed channels, and one interactive channel. A number of new HD channels launched in 2014, from a new group of multiplexes awarded to Arqiva. The new HD channels were launched in selected areas on 10 December 2013 with a further roll-out during 2014.

DTV Services' delivery of standard-definition television and radio is labelled Freeview, while its delivery of HDTV is called Freeview HD. Reception of Freeview requires a Freeview tuner, either in a separate set-top box or built into the TV set. Since 2008 all new TV sets sold in the United Kingdom have a built-in Freeview tuner. Freeview HD requires a HDTV-capable tuner. Digital video recorders (DVRs) with a built-in Freeview tuner are labelled Freeview+. Depending on model, DVRs and HDTV sets with a Freeview tuner may offer standard Freeview or Freeview HD.

The technical specification for Freeview is published and maintained by the Digital TV Group, the industry association for digital TV in the UK which also provide the test and conformance regime for Freeview, Freeview + and Freeview HD products. DMOL (DTT Multiplex Operators Ltd.), a company owned by the operators of the six DTT multiplexes (BBC, ITV, C4, and Arqiva) is responsible for technical platform management and policy, including the electronic programme guide and channel numbering.Since the completion of the digital switch-over on 24 October 2012, there is no terrestrial analogue television being broadcast in the United Kingdom, and all broadcast terrestrial TV is delivered through digital terrestrial television.

High-definition television

High-definition television (HDTV) is a television system providing an image resolution that is of substantially higher resolution than that of standard-definition television. This can be either analog or digital. HDTV is the current standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television, Blu-rays, and streaming video.

HDTV may be transmitted in various formats:

720p 1280×720p: 923,600 pixels (~0.92 MP) per frame

1080i 1920×1080i: 1,036,800 pixels (~1.04 MP) per field or 2,073,600 pixels (~2.07 MP) per frame

1080p 1920×1080p: not a broadcast standard for ATSC 1.0

Some countries also use a non-standard CEA resolution, such as 1440×1080i: 777,600 pixels (~0.78 MP) per field or 1,555,200 pixels (~1.56 MP) per frameThe letter "p" here stands for progressive scan, while "i" indicates interlaced.

When transmitted at two megapixels per frame, HDTV provides about five times as many pixels as SD (standard-definition television). The increased resolution provides for a clearer, more detailed picture. In addition, progressive scan and higher frame rates result in a picture with less flicker and better rendering of fast motion. HDTV as is known today first started official broadcasting in 1989 in Japan, under the MUSE/Hi-Vision analog system. HDTV was widely adopted worldwide in the late 2000s.

Low-definition television

Low-definition television (LDTV) refers to television systems that have a lower screen resolution than standard-definition television systems. The term is usually used in reference to digital television, in particular when broadcasting at the same (or similar) resolution as low-definition analog TV systems. Mobile DTV systems usually transmit in low definition, as do all slow-scan TV systems.


NTSC, named after the National Television System Committee, is the analog television color system that was used in North America from 1954 and until digital conversion, was used in most of the Americas (except Brazil, Argentina, Paraguay, Uruguay, and French Guiana); Myanmar; South Korea; Taiwan; Philippines; Japan; and some Pacific island nations and territories (see map).

The first NTSC standard was developed in 1941 and had no provision for color. In 1953 a second NTSC standard was adopted, which allowed for color television broadcasting which was compatible with the existing stock of black-and-white receivers. NTSC was the first widely adopted broadcast color system and remained dominant until the 2000s, when it started to be replaced with different digital standards such as ATSC and others.

Most countries using the NTSC standard, as well as those using other analog television standards, have switched to, or are in process of switching to newer digital television standards, there being at least four different standards in use around the world. North America, parts of Central America, and South Korea are adopting or have adopted the ATSC standards, while other countries (such as Japan) are adopting or have adopted other standards instead of ATSC. After nearly 70 years, the majority of over-the-air NTSC transmissions in the United States ceased on January 1, 2010, and by August 31, 2011 in Canada and most other NTSC markets. The majority of NTSC transmissions ended in Japan on July 24, 2011, with the Japanese prefectures of Iwate, Miyagi, and Fukushima ending the next year. After a pilot program in 2013, most full-power analog stations in Mexico left the air on ten dates in 2015, with some 500 low-power and repeater stations allowed to remain in analog until the end of 2016. Digital broadcasting allows higher-resolution television, but digital standard definition television continues to use the frame rate and number of lines of resolution established by the analog NTSC standard.

Pixel aspect ratio

Pixel aspect ratio (often abbreviated PAR) is a mathematical ratio that describes how the width of a pixel in a digital image compares to the height of that pixel.

Most digital imaging systems display an image as a grid of tiny, square pixels. However, some imaging systems, especially those that must be compatible with standard-definition television motion pictures, display an image as a grid of rectangular pixels, in which the pixel width and height are different. Pixel aspect ratio describes this difference.

Use of pixel aspect ratio mostly involves pictures pertaining to standard-definition television and some other exceptional cases. Most other imaging systems, including those that comply with SMPTE standards and practices, use square pixels.


Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, and in two or three dimensions and sound. The term can refer to a television set, a television program ("TV show"), or the medium of television transmission. Television is a mass medium for advertising, entertainment and news.

Television became available in crude experimental forms in the late 1920s, but it would still be several years before the new technology would be marketed to consumers. After World War II, an improved form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US and most other developed countries. The availability of multiple types of archival storage media such as Betamax, VHS tape, local disks, DVDs, flash drives, high-definition Blu-ray Discs, and cloud digital video recorders has enabled viewers to watch pre-recorded material—such as movies—at home on their own time schedule. For many reasons, especially the convenience of remote retrieval, the storage of television and video programming now occurs on the cloud. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity. Another development was the move from standard-definition television (SDTV) (576i, with 576 interlaced lines of resolution and 480i) to high-definition television (HDTV), which provides a resolution that is substantially higher. HDTV may be transmitted in various formats: 1080p, 1080i and 720p. Since 2010, with the invention of smart television, Internet television has increased the availability of television programs and movies via the Internet through streaming video services such as Netflix, Amazon Video, iPlayer and Hulu.

In 2013, 79% of the world's households owned a television set. The replacement of early bulky, high-voltage cathode ray tube (CRT) screen displays with compact, energy-efficient, flat-panel alternative technologies such as LCDs (both fluorescent-backlit and LED), OLED displays, and plasma displays was a hardware revolution that began with computer monitors in the late 1990s. Most TV sets sold in the 2000s were flat-panel, mainly LEDs. Major manufacturers announced the discontinuation of CRT, DLP, plasma, and even fluorescent-backlit LCDs by the mid-2010s. In the near future, LEDs are expected to be gradually replaced by OLEDs. Also, major manufacturers have announced that they will increasingly produce smart TVs in the mid-2010s. Smart TVs with integrated Internet and Web 2.0 functions became the dominant form of television by the late 2010s.Television signals were initially distributed only as terrestrial television using high-powered radio-frequency transmitters to broadcast the signal to individual television receivers. Alternatively television signals are distributed by coaxial cable or optical fiber, satellite systems and, since the 2000s via the Internet. Until the early 2000s, these were transmitted as analog signals, but a transition to digital television is expected to be completed worldwide by the late 2010s. A standard television set is composed of multiple internal electronic circuits, including a tuner for receiving and decoding broadcast signals. A visual display device which lacks a tuner is correctly called a video monitor rather than a television.

Television standards conversion

Television standards conversion is the process of changing one type of television system to another. The most common is from NTSC to PAL or the other way around. This is done so television programs in one nation may be viewed in a nation with a different standard. The video is fed through a video standards converter that changes the video to a different video system.

Converting between different numbers of lines and different frame rates in video pictures is a complex technical problem. However, the international exchange of television programming makes standards conversion necessary and in many cases mandatory.

The Score (Philippine TV program)

The Score is a Philippine English-language sports news television program broadcast on ABS-CBN Sports and Action (S+A), debuting on January 20, 2014, just two days after the network began operating. The show premiered on January 20, 2014 and airs every Mondays to Fridays at 6:00 PM (PST).

Video editing

Video editing is the manipulation and arrangement of video shots. Video editing is used to structure and present all video information, including films and television shows, video advertisements and video essays. Video editing has been dramatically democratized in recent years by editing software available for personal computers.


XHNAT-TDT is a Grupo Multimedios owned and operated station in Nuevo Laredo, Tamaulipas. The station is primarily affiliated to Multimedios Plus. It serves the Laredo, Texas — Nuevo Laredo areas. When XHNAT first went on the air it was a Galavisión-rebroadcaster Televisa affiliate, part of the Grupo Multimedios concession of 1994, before they decided to switch to their own television network Multimedios Televisión. Milenio TV and Teleritmo are available on its subchannels 45.2 and 45.3.


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-difference and red-difference chroma components. Y′ (with prime) is distinguished from Y, which is luminance, meaning that light intensity is nonlinearly encoded based on gamma corrected RGB primaries.

Y′CbCr color spaces are defined by a mathematical coordinate transformation from an associated RGB color space. If the underlying RGB color space is absolute, the Y′CbCr color space is an absolute color space as well; conversely, if the RGB space is ill-defined, so is Y′CbCr.


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