High-definition video

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High-definition video (HDTV Video or HD video) is video of higher resolution and quality than standard-definition. While there is no standardized meaning for high-definition, generally any video image with considerably more than 480 vertical scan lines (North America) or 576 vertical lines (Europe) is considered high-definition. 480 scan lines is generally the minimum even though the majority of systems greatly exceed that. Images of standard resolution captured at rates faster than normal (60 frames/second North America, 50 fps Europe), by a high-speed camera may be considered high-definition in some contexts. Some television series shot on high-definition video are made to look as if they have been shot on film, a technique which is often known as filmizing.

Contents

History

The first electronic scanning format, 405 lines, was the first "high definition" television system, since the mechanical systems it replaced had far fewer. From 1939, Europe and the US tried 605 and 441 lines until, in 1941, the FCC mandated 525 for the US. In wartime France, René Barthélemy tested higher resolutions, up to 1,042. In late 1949, official French transmissions finally began with 819. In 1984, however, this standard was abandoned for 625-line color on the TF1 network.

Analog

Modern HD specifications date to the early 1980s, when Japanese engineers developed the HighVision 1,125-line interlaced TV standard (also called MUSE) that ran at 60 frames per second. The Sony HDVS system was presented at an international meeting of television engineers in Algiers, April 1981 and Japan's NHK presented its analog high-definition television (HDTV) system at a Swiss conference in 1983.

The NHK system was standardized in the United States as Society of Motion Picture and Television Engineers (SMPTE) standard #240M in the early 1990s, but abandoned later on when it was replaced by a DVB analog standard. HighVision video is still usable for HDTV video interchange, but there is almost no modern equipment available to perform this function. Attempts at implementing HighVision as a 6 MHz broadcast channel were mostly unsuccessful. All attempts at using this format for terrestrial TV transmission were abandoned by the mid-1990s.[ citation needed ]

Europe developed HD-MAC (1,250 lines, 50 Hz), a member of the MAC family of hybrid analogue/digital video standards; however, it never took off as a terrestrial video transmission format. HD-MAC was never designated for video interchange except by the European Broadcasting Union.

Digital

High-definition digital video was not possible with uncompressed video due to impractically high memory and bandwidth requirements, with a bit-rate exceeding 1  Gbps for full HD video. [1] Digital HDTV was enabled by the development of discrete cosine transform (DCT) video compression. [2] The DCT is a lossy compression technique that was first proposed by Nasir Ahmed in 1972, [3] and was later adapted into a motion-compensated DCT algorithm for video coding standards such as the H.26x formats from 1988 onwards and the MPEG formats from 1993 onwards. [4] [5] Motion-compensated DCT compression significantly reduced the amount of memory and bandwidth required for digital video, capable of achieving a data compression ratio of around 100:1 compared to uncompressed video. [6] By the early 1990s, DCT video compression had been widely adopted as the video coding standard for HDTV. [2]

The current high-definition video standards in North America were developed during the course of the advanced television process initiated by the Federal Communications Commission in 1987 at the request of American broadcasters. In essence, the end of the 1980s was a death knell for most analog high definition technologies that had developed up to that time.

The FCC process, led by the Advanced Television Systems Committee (ATSC) adopted a range of standards from interlaced 1,080-line video (a technical descendant of the original analog NHK 1125/30 Hz system) with a maximum frame rate of 30 Hz, (60 fields per second) and 720-line video, progressively scanned, with a maximum frame rate of 60 Hz. In the end, however, the DVB standard of resolutions (1080, 720, 480) and respective frame rates (24, 25, 30) were adopted in conjunction with the Europeans that were also involved in the same standardization process. The FCC officially adopted the ATSC transmission standard in 1996 (which included both HD and SD video standards).

In the early 2000s, it looked as if DVB would be the video standard far into the future. However, both Brazil and China have adopted alternative standards for high-definition video[ citation needed ] that preclude the interoperability that was hoped for after decades of largely non-interoperable analog TV broadcasting.

Technical details

This chart shows the most common display resolutions, with the color of each resolution type indicating the display ratio (e.g., red indicates a 4:3 ratio) Vector Video Standards2.svg
This chart shows the most common display resolutions, with the color of each resolution type indicating the display ratio (e.g., red indicates a 4:3 ratio)

High definition video (prerecorded and broadcast) is defined threefold, by:

Often, the rate is inferred from the context, usually assumed to be either 50 Hz (Europe) or 60 Hz (USA), except for 1080p, which denotes 1080p24, 1080p25, and 1080p30, but also 1080p50 and 1080p60.

A frame or field rate can also be specified without a resolution. For example, 24p means 24 progressive scan frames per second and 50i means 25 progressive frames per second, consisting of 50 interlaced fields per second. Most HDTV systems support some standard resolutions and frame or field rates. The most common are noted below. High-definition signals require a high-definition television or computer monitor in order to be viewed. High-definition video has an aspect ratio of 16:9 (1.78:1). The aspect ratio of regular widescreen film shot today is typically 1.85:1 or 2.39:1 (sometimes traditionally quoted at 2.35:1). Standard-definition television (SDTV) has a 4:3 (1.33:1) aspect ratio, although in recent years many broadcasters have transmitted programs "squeezed" horizontally in 16:9 anamorphic format, in hopes that the viewer has a 16:9 set which stretches the image out to normal-looking proportions, or a set which "squishes" the image vertically to present a "letterbox" view of the image, again with correct proportions.

Common high-definition video modes

Video modeFrame size in pixels (W×H)Pixels per image1Scanning typeFrame rate (Hz)
720p (also known as HD Ready) 1,280×720921,600 Progressive 23.976, 24, 25, 29.97, 30, 50, 59.94, 60, 72
1080i (also known as Full HD) 1,920×1,0802,073,600 Interlaced 25 (50 fields/s), 29.97 (59.94 fields/s), 30 (60 fields/s)
1080p (also known as Full HD) 1,920×1,0802,073,600 Progressive 24 (23.976), 25, 30 (29.97), 50, 60 (59.94)
1440p (also known as Quad HD) 2,560×1,4403,686,400 Progressive 24 (23.976), 25, 30 (29.97), 50, 60 (59.94)

Ultra high-definition video modes

Video modeFrame size in pixels (W×H)Pixels per image1Scanning typeFrame rate (Hz)
2000 2,048×1,5363,145,728 Progressive 24, 60
2160p (also known as 4K UHD) 3,840×2,1608,294,400 Progressive 60, 120
2540p 4,520×2,54011,480,800 Progressive 24, 30
4000p 4,096×3,07212,582,912 Progressive 24, 30, 60
4320p (also known as 8K UHD) 7,680×4,32033,177,600 Progressive 60, 120

Note: 1 Image is either a frame or, in case of interlaced scanning, two fields (EVEN and ODD).

Also, there are less common but still popular UltraWide resolutions, such as 2560×1080p (1080p UltraWide).

HD content

High-definition image sources include terrestrial broadcast, direct broadcast satellite, digital cable, high definition disc (BD), digital cameras, Internet downloads, and video game consoles.

Blu-ray Discs were jointly developed by 9 initial partners including Sony and Phillips (which jointly developed CDs for audio), and Pioneer (which developed its own Laser-disc previously with some success) among others. HD-DVD discs were primarily developed by Toshiba and NEC with some backing from Microsoft, Warner Bros., Hewlett Packard, and others. On February 19, 2008 Toshiba announced it was abandoning the format and would discontinue development, marketing and manufacturing of HD-DVD players and drives.

Types of recorded media

The high resolution photographic film used for cinema projection is exposed at the rate of 24 frames per second but usually projected at 48, each frame getting projected twice helping to minimise flicker. One exception to this was the 1986 National Film Board of Canada short film Momentum , which briefly experimented with both filming and projecting at 48 frame/s, in a process known as IMAX HD.

Depending upon available bandwidth and the amount of detail and movement in the image, the optimum format for video transfer is either 720p24 or 1080p24. When shown on television in PAL system countries, film must be projected at the rate of 25 frames per second by accelerating it by 4.1 percent. In NTSC standard countries, the projection rate is 30 frames per second, using a technique called 3:2 pull-down. One film frame is held for three video fields (1/20 of a second), and the next is held for two video fields (1/30 of a second) and then the process is repeated, thus achieving the correct film projection rate with two film frames shown in one twelfth of a second.

Older (pre-HDTV) recordings on video tape such as Betacam SP are often either in the form 480i60 or 576i50. These may be upconverted to a higher resolution format, but removing the interlace to match the common 720p format may distort the picture or require filtering which actually reduces the resolution of the final output.

Non-cinematic HDTV video recordings are recorded in either the 720p or the 1080i format. The format used is set by the broadcaster (if for television broadcast). In general, 720p is more accurate with fast action, because it progressively scans frames, instead of the 1080i, which uses interlaced fields and thus might degrade the resolution of fast images.

720p is used more for Internet distribution of high-definition video, because computer monitors progressively scan; 720p video has lower storage-decoding requirements than either the 1080i or the 1080p. This is also the medium for high-definition broadcasts around the world and 1080p is used for Blu-ray movies.

HD in filmmaking

Film as a medium has inherent limitations, such as difficulty of viewing footage while recording, and suffers other problems, caused by poor film development/processing, or poor monitoring systems. Given that there is increasing use of computer-generated or computer-altered imagery in movies, and that editing picture sequences is often done digitally, some directors have shot their movies using the HD format via high-end digital video cameras. While the quality of HD video is very high compared to SD video, and offers improved signal/noise ratios against comparable sensitivity film, film remains able to resolve more image detail than current HD video formats. In addition some films have a wider dynamic range (ability to resolve extremes of dark and light areas in a scene) than even the best HD cameras. Thus the most persuasive arguments for the use of HD are currently cost savings on film stock and the ease of transfer to editing systems for special effects.

Depending on the year and format in which a movie was filmed, the exposed image can vary greatly in size. Sizes range from as big as 24 mm × 36 mm for VistaVision/Technirama 8 perforation cameras (same as 35 mm still photo film) going down through 18 mm × 24 mm for Silent Films or Full Frame 4 perforations cameras to as small as 9 mm × 21 mm in Academy Sound Aperture cameras modified for the Techniscope 2 perforation format. Movies are also produced using other film gauges, including 70 mm films (22 mm × 48 mm) or the rarely used 55 mm and CINERAMA.

The four major film formats provide pixel resolutions (calculated from pixels per millimeter) roughly as follows:

In the process of making prints for exhibition, this negative is copied onto other film (negative → interpositive → internegative → print) causing the resolution to be reduced with each emulsion copying step and when the image passes through a lens (for example, on a projector). In many cases, the resolution can be reduced down to 1/6 of the original negative's resolution (or worse).[ citation needed ] Note that resolution values for 70 mm film are higher than those listed above.

HD on the World Wide Web/HD streaming

A number of online video streaming/on demand and digital download services offer HD video, among them YouTube, Vimeo, dailymotion, Amazon Video On Demand, Netflix Watch Instantly, and others. Due to heavy compression, the image detail produced by these formats is far below that of broadcast HD, and often even inferior to DVD-Video (3-9 Mbit/s MP2) upscaled to the same image size. [7] The following is a chart of numerous online services and their HD offering:

World Wide Web HD resolutions

SourceCodecHighest resolution (W×H)Total bit rate/bandwidthVideo bit rateAudio bit rate
Amazon Video [note 1] VC-1 [8] 1280×720 [9] 2.5-6 Mbit/s
BBC iPlayer H.264 [10] 1280×720 [11] [note 2] 3.2 Mbit/s [10] 3 Mbit/s [10] 192 kbit/s [10]
blinkbox1280×7202.25 Mbit/s (SD) and 4.5 Mbit/s (HD)2.25 - 4.5 Mbit/s192 kbit/s
Blockbuster Online 1280×720
CBS.com/TV.com 1920×1080 [12] 3.5 Mbit/s and 2.5 Mbits (720p) [12]
Dacast VP6, H.264 [13] Unknown5 Mbit/s [14]
Hulu On2 Flash VP6 [15] 1280×720 [16] 2.5 Mbit/s [17]
iPlayerHD FLV, QuickTime H.264, MP4 H.264 [18] 1920×1080 [19] 2 Mbit/s and 5 Mbit/s [20]
iTunes/Apple TV QuickTime H.264 [21] 1920×1080 [21]
MetaCDN MPEG-4, FLV, OGG, WebM, 3GP [22] No Limit [23]
Netflix Watch Instantly VC-1 [24] 3840×2160 [25] 25 Mbit/s [26] 2.6 Mbit/s and 3.8 Mbit/s (1080p) [27]
PlayStation Video H.264/MPEG-4 AVC [28] 1920×1080 [28] 8 Mbit/s [28] 256 kbit/s [28]
StreamShark H.264, FLV, OGV, WebM, VP8, VP9 [29] 1920×1080 [30]
Vimeo H.264 [31] 1920×1080 [32] 4 Mbit/s [33] 320 kbit/s [34]
Vudu H.264 [35] 1920×1080 [36] 4.5 Mbit/s [37]
Xbox Video [note 3] 1920×1080 [38]
YouTube H.264/MPEG-4 AVC, VP9 7680×4320
StreamHash Mp4 [39] 1920×1080 [40]
  1. Formerly "Amazon Unbox", which now refers to a video player software, and later "Amazon Video on Demand".
  2. During live events "BBC iPlayer" streams have a resolution of 1024×576.
  3. Formerly "Xbox Live Marketplace Video Store", but replaced by "Xbox Video" in 2012.

HD in video surveillance

An increasing number of manufacturers of security cameras now offer HD cameras. The need for high resolution, color fidelity, and frame rate is acute for surveillance purposes to ensure that the quality of the video output is of an acceptable standard that can be used both for preventative surveillance as well as for evidence purposes. These needs, however, must be balanced against the additional storage capacity required by HD video.

HD in video gaming

Both the PlayStation 3 game console and Xbox 360 can output native 1080p through HDMI or component cables, but the systems have few games which appear in 1080p; most games only run natively at 720p or less, but can be upscaled to 1080p. The Wii can output up to 480p (enhanced-definition) over component, which while not HD, is very useful for HDTVs as it avoids de-interlacing artifacts. The Wii can also output 576i in PAL regions.

Visually, native 1080p produces a sharper and clearer picture compared to upscaled 1080p. Though only a handful of games available have the native resolution of 1080p, all games on the Xbox 360 and PlayStation 3 can be upscaled up to this resolution. Xbox 360 and PlayStation 3 games are labeled with the output resolution on the back of their packaging, although on Xbox 360 this indicates the resolution it will upscale to, not the native resolution of the game.

Generally, PC games are only limited by the display's resolution size. Drivers are capable of supporting very high resolutions, depending on the chipset of the video card. Many game engines support resolutions of 5760×1080 or 5760×1200 (typically achieved with three 1080p displays in a multi-monitor setup) and nearly all will display 1080p at minimum. 1440p and 4K are typically supported resolutions for PC gaming as well.

Currently all consoles, Nintendo's Wii U and Nintendo Switch, Microsoft's Xbox One, and Sony's PlayStation 4 display games 1080p natively. The Nintendo Switch is an unusual case, due to its hybrid nature as both a home console and a handheld: the built-in screen displays games at 1080p maximum, but the console can natively display imagery at 1080p when docked. PlayStation 4 is able to display in 4K, though strictly only for displaying pictures.

See also

Related Research Articles

Video electronic medium for the recording, copying and broadcasting of moving visual images

Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode ray tube (CRT) systems which were later replaced by flat panel displays of several types.

Interlaced video technique for doubling the perceived frame rate of a video display without consuming extra bandwidth

Interlaced video 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 enhances motion perception to the viewer, and reduces flicker by taking advantage of the phi phenomenon.

Progressive scanning is a format of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence. This is in contrast to interlaced video used in traditional analog television systems where only the odd lines, then the even lines of each frame are drawn alternately, so that only half the number of actual image frames are used to produce video. The system was originally known as "sequential scanning" when it was used in the Baird 240 line television transmissions from Alexandra Palace, United Kingdom in 1936. It was also used in Baird's experimental transmissions using 30 lines in the 1920s. Progressive scanning became universally used in computer screens beginning in the early 21st century.

Telecine process of transferring motion picture film into video

Telecine is the process of transferring motion picture film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process. Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as television sets, video cassette recorders (VCR), DVD, Blu-ray Disc or computers. Initially, this allowed television broadcasters to produce programmes using film, usually 16mm stock, but transmit them in the same format, and quality, as other forms of television production. Furthermore, telecine allows film producers, television producers and film distributors working in the film industry to release their products on video and allows producers to use video production equipment to complete their filmmaking projects. Within the film industry, it is also referred to as a TK, because TC is already used to designate timecode.

Advanced Television Systems Committee (ATSC) standards are a 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 standard, used mostly in the United States, Mexico and Canada. Other former users of NTSC, like Japan, have not used ATSC during their digital television transition because they adopted their own system called ISDB.

Enhanced-definition television, or extended-definition television (EDTV) is a 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).

HD-MAC was a proposed broadcast television systems standard by the European Commission in 1986, a part of Eureka 95 project. It is an early attempt by the EEC to provide High-definition television (HDTV) in Europe. It is a complex mix of analogue signal, multiplexed with digital sound, and assistance data for decoding (DATV). The video signal was encoded with a modified D2-MAC encoder.

D5 HD

D-5 is a professional digital video format introduced by Panasonic in 1994. Like Sony's D-1 (8-bit), it is an uncompressed digital component system (10-bit), but uses the same half-inch tapes as Panasonic's digital composite D-3 format. A 120 min. D-3 tape will record 60 min. in D-5/D-5 HD mode. D-5 standard definition decks can be retrofitted to record high definition with the use of an external HD input/output box. The HD deck conversion does not allow for any error correction that exists on standard definition recordings, as the full bandwidth of the tape is required for the HD recording.

HDV format for recording of high-definition video on DV cassette tape

HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon, and Sharp. The four companies formed the HDV consortium in September 2003.

480p is the shorthand name for a family of video display resolutions. The p stands for progressive scan, i.e. non-interlaced. The 480 denotes a vertical resolution of 480 pixels, usually with a horizontal resolution of 640 pixels and 4:3 aspect ratio or a horizontal resolution of 854 or less pixels for an approximate 16:9 aspect ratio. Since a pixel count must be a whole number, in Wide VGA displays it is generally rounded up to 854 to ensure inclusion of the entire image. The frames are displayed progressively as opposed to interlaced. 480p was used for many early plasma televisions. Standard definition has always been a 4:3 aspect ratio with a pixel resolution of 640 × 480 pixels.

720p resolution

720p is a progressive HDTV signal format with 720 horizontal lines and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcasting standards include a 720p format, which has a resolution of 1280×720; however, there are other formats, including HDV Playback and AVCHD for camcorders, that use 720p images with the standard HDTV resolution. The frame rate is standards-dependent, and for conventional broadcasting appears in 50 progressive frames per second in former PAL/SECAM countries, and 59.94 frames per second in former NTSC countries.

1080i is an abbreviation referring to a combination of frame resolution and scan type, used in high-definition television (HDTV) and high-definition video. The number "1080" refers to the number of horizontal lines on the screen. The "i" is an abbreviation for "interlaced"; this indicates that only the odd lines, then the even lines of each frame are drawn alternately, so that only half the number of actual image frames are used to produce video. A related display resolution is 1080p, which also has 1080 lines of resolution; the "p" refers to progressive scan, which indicates that the lines of resolution for each frame are "drawn" in on the screen sequence.

576p is the shorthand name for a video display resolution. The p stands for progressive scan, i.e. non-interlaced, the 576 for a vertical resolution of 576 pixels, usually with a horizontal resolution of 768, 720 or 704 pixels. The frame rate can be given explicitly after the letter.

H.262 or MPEG-2 Part 2 is a video coding format standardised and jointly maintained by ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Moving Picture Experts Group (MPEG), and developed with the involvement of many companies. It is the second part of the ISO/IEC MPEG-2 standard. The ITU-T Recommendation H.262 and ISO/IEC 13818-2 documents are identical.

1080p Video mode

1080p is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vertically; the p stands for progressive scan, i.e. non-interlaced. The term usually assumes a widescreen aspect ratio of 16:9, implying a resolution of 2.1 megapixels. It is often marketed as Full HD or FHD, to contrast 1080p with 720p resolution screens. 1080p can sometimes also be informally referred to as 2K.

Progressive segmented Frame is a scheme designed to acquire, store, modify, and distribute progressive scan video using interlaced equipment.

In video, a field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame. When the fields are displayed on a video monitor they are "interlaced" so that the content of one field will be used on all of the odd-numbered lines on the screen and the other field will be displayed on the even lines. Converting fields to a still frame image requires a process called deinterlacing, in which the missing lines are duplicated or interpolated to recreate the information that would have been contained in the discarded field. Since each field contains only half of the information of a full frame, however, deinterlaced images do not have the resolution of a full frame.

HD Lite is the re-transmission of a particular HDTV channel at reduced picture quality compared to the source.

High-definition television describes a television system providing an image resolution of substantially higher resolution than the previous generation of technology. The term has been used since 1936, but in modern times refers to the generation following standard-definition television (SDTV), often abbreviated to HDTV or HD-TV. It is the current standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television, Blu-ray discs, and streaming video.

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Further reading