Editing Digital video

{{Short description|Digital electronic representation of moving visual images}}
{{about|digital techniques applied to video|the standard format for storing digital video|DV (video format)|other uses}}
{{Use American English|date=December 2024}}

[[File:Sony_Handycam_DCR-VX700E_MiniDV_camcorder.jpg|thumb|Sony digital video camera used for recording content]]

'''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 signal]]s. Digital video comprises a series of [[digital image]]s displayed in rapid succession, usually at 24, 25, 30, or 60 [[frames per second]]. Digital video has many advantages such as easy copying, multicasting, sharing and storage.

Digital video was first introduced commercially in 1986 with the [[Sony D1]] format, which recorded an uncompressed [[standard-definition]] [[component video]] signal in digital form. In addition to [[Uncompressed video|uncompressed formats]], popular [[Data compression|compressed]] digital video formats today include [[MPEG-2]], [[H.264]] and [[AV1]]. Modern interconnect standards used for playback of digital video include [[HDMI]], [[DisplayPort]], [[Digital Visual Interface]] (DVI) and [[serial digital interface]] (SDI).

Digital video can be copied and reproduced with no degradation in quality. In contrast, when analog sources are copied, they experience [[generation loss]]. Digital video can be stored on digital media such as [[Blu-ray Disc]], on [[computer data storage]], or [[streaming video|streamed]] over the [[Internet]] to [[end user]]s who watch content on a personal computer or mobile device screen or a digital [[smart TV]]. Today, digital video content such as [[TV show]]s and [[movie]]s also includes a [[digital audio]] soundtrack.

==History==
===Cameras===
{{Further|Digital cinematography|Image sensor|Video camera}}

The basis for [[digital video camera]]s is [[metal–oxide–semiconductor]] (MOS) [[image sensors]].<ref name="Williams">{{cite book |last1=Williams |first1=J. B. |title=The Electronics Revolution: Inventing the Future |date=2017 |publisher=Springer |isbn=9783319490885 |pages=245–8 |url=https://books.google.com/books?id=v4QlDwAAQBAJ&pg=PA245}}</ref> The first practical [[semiconductor]] image sensor was the [[charge-coupled device]] (CCD), invented in 1969<ref>{{Cite book | title = Scientific charge-coupled devices | author = James R. Janesick | publisher = SPIE Press | year = 2001 | isbn = 978-0-8194-3698-6 | pages = 3–4 | url = https://books.google.com/books?id=3GyE4SWytn4C&pg=PA3 }}</ref> by Willard S. Boyle, who won a Nobel Prize for his work in physics.<ref>{{Cite journal|date=2009|title=2009 Nobel Prize in Physics awarded to Kao, Boyle, and Smith|url=http://dx.doi.org/10.1063/pt.5.023739|journal=Physics Today|issue=10 |page=14182 |doi=10.1063/pt.5.023739|bibcode=2009PhT..2009j4182. |issn=1945-0699}}</ref> Following the commercialization of CCD sensors during the late 1970s to early 1980s, the [[entertainment industry]] slowly began transitioning to [[digital imaging]] and digital video from analog video over the next two decades.<ref>{{cite book |last1=Stump |first1=David |title=Digital Cinematography: Fundamentals, Tools, Techniques, and Workflows |date=2014 |publisher=[[CRC Press]] |isbn=978-1-136-04042-9 |pages=83–5 |url=https://books.google.com/books?id=c-MjAwAAQBAJ&pg=PA83}}</ref> The CCD was followed by the [[CMOS]] [[active-pixel sensor]] ([[CMOS sensor]]),<ref>{{cite book |last1=Stump |first1=David |title=Digital Cinematography: Fundamentals, Tools, Techniques, and Workflows |date=2014 |publisher=[[CRC Press]] |isbn=978-1-136-04042-9 |pages=19–22 |url=https://books.google.com/books?id=c-MjAwAAQBAJ&pg=PA19}}</ref> developed in the 1990s.<ref name="Fossum2014">{{cite journal |last1=Fossum |first1=Eric R. |author1-link=Eric Fossum |last2=Hondongwa |first2=D. B. |title=A Review of the Pinned Photodiode for CCD and CMOS Image Sensors |journal=IEEE Journal of the Electron Devices Society |date=2014 |volume=2 |issue=3 |pages=33–43 |doi=10.1109/JEDS.2014.2306412 |doi-access=free }}</ref><ref name=fossum93>{{cite book |last1=Fossum |first1=Eric R. |chapter=Active pixel sensors: Are CCDS dinosaurs? |author1-link=Eric Fossum |title=Charge-Coupled Devices and Solid State Optical Sensors III |journal=SPIE Proceedings Vol. 1900: Charge-Coupled Devices and Solid State Optical Sensors III |volume=1900 |date=12 July 1993 |doi=10.1117/12.148585 |bibcode=1993SPIE.1900....2F |citeseerx=10.1.1.408.6558 |publisher=International Society for Optics and Photonics |pages=2–14 |s2cid=10556755 |editor1-last=Blouke |editor1-first=Morley M.}}</ref>

Major films{{efn|Defined as the top 200 grossing live-action films}} shot on digital video overtook those shot on film in 2013. Since 2016 over 90% of major films were shot on digital video.<ref>{{Cite web |date=2019-02-11 |title=The use of digital vs celluloid film on Hollywood movies |url=https://stephenfollows.com/digital-vs-film-on-hollywood-movies/ |access-date=2019-10-23 |website=Stephen Follows |language=en-GB}}</ref><ref>{{Cite web |title=Robert Rodriguez Film Once Upon a Time in Mexico This is a structural review. |url=http://www.writework.com/essay/robert-rodriguez-film-once-upon-time-mexico-structural-rev |access-date=2013-04-22 |publisher=WriteWork}}</ref> {{As of|2017}}, 92% of films are shot on digital.<ref>{{Cite news |date=23 August 2018 |title=Maybe the war between digital and film isn't a war at all |language=en-us |work=[[The A.V. Club]] |url=https://www.avclub.com/maybe-the-war-between-digital-and-film-isn-t-a-war-at-a-1828527569 |access-date=26 November 2019}}</ref> Only 24 major films released in 2018 were shot on 35mm.<ref>{{Cite web |last=Rizov |first=Vadim |date=24 April 2019 |title=24 Films Shot on 35mm Released in 2018 |url=https://filmmakermagazine.com/107353-23-films-35mm-released-in-2018/ |access-date=2019-09-14 |website=Filmmaker Magazine |language=en-US}}</ref> Today, cameras from companies like [[Sony]], [[Panasonic]], [[JVC]] and [[Canon (company)|Canon]] offer a variety of choices for shooting high-definition video. At the high end of the market, there has been an emergence of cameras aimed specifically at the digital cinema market. These cameras from [[Sony]], [[Vision Research Phantom|Vision Research]], [[Arri]], [[Blackmagic Design]], [[Panavision]], [[Grass Valley (company)|Grass Valley]] and [[Red Digital Cinema Camera Company|Red]] offer resolution and [[dynamic range]] that exceeds that of traditional video cameras, which are designed for the limited needs of [[broadcast television]].<ref>{{Cite web|title=The Heart of a Phone Camera: The CMOS Active Pixel Image Sensor|url=http://large.stanford.edu/courses/2012/ph250/lu2/|access-date=2021-03-26|website=large.stanford.edu}}</ref>
[[File:Betacam_SP_camera.jpg|thumb|A Betacam SP camera, originally developed in 1986 by Sony]]

===Coding===
{{Further|Video coding format#History}}

In the 1970s, [[pulse-code modulation]] (PCM) induced the birth of digital [[video coding]], demanding high [[bit rate]]s of 45-140&nbsp;Mbit/s for [[standard-definition]] (SD) content. By the 1980s, the [[discrete cosine transform]] (DCT) became the standard for digital [[video compression]].<ref>{{Cite book |last=Hanzo |first=Lajos |url=https://www.worldcat.org/oclc/181368622 |title=Video compression and communications: from basics to H.261, H.263, H.264, MPEG2, MPEG4 for DVB and HSDPA-style adaptive turbo-transceivers |date=2007 |publisher=IEEE Press |others=Peter J. Cherriman, Jürgen Streit, Lajos Hanzo |isbn=978-0-470-51992-9 |edition=2nd |location=Hoboken, NJ |oclc=181368622}}</ref>

The first digital [[video coding standard]] was [[H.120]], created by the (International Telegraph and Telephone Consultative Committee) or [[CCITT]] (now ITU-T) in 1984. H.120 was not practical due to weak performance.<ref name="history">{{cite web |title=The History of Video File Formats Infographic |url=http://www.real.com/resources/digital-video-file-formats/ |website=[[RealNetworks]] |access-date=5 August 2019 |date=22 April 2012}}</ref> H.120 was based on [[differential pulse-code modulation]] (DPCM), a compression algorithm that was inefficient for video coding. During the late 1980s, a number of companies began experimenting with DCT, a much more efficient form of compression for video coding. The CCITT received 14 proposals for DCT-based video compression formats, in contrast to a single proposal based on [[vector quantization]] (VQ) compression. The [[H.261]] standard was developed based on DCT compression,<ref name="Ghanbari">{{cite book|last1=Ghanbari|first1=Mohammed|url=https://books.google.com/books?id=7XuU8T3ooOAC&pg=PA1|title=Standard Codecs: Image Compression to Advanced Video Coding|date=2003|publisher=[[Institution of Engineering and Technology]]|isbn=9780852967102|pages=1–2}}</ref> becoming first practical video coding standard.<ref name="history" /> Since H.261, DCT compression has been adopted by all the major video coding standards that followed.<ref name="Ghanbari"/>

[[MPEG-1]], developed by the [[Motion Picture Experts Group]] (MPEG), followed in 1991, and it was designed to compress [[VHS]]-quality video. It was succeeded in 1994 by [[MPEG-2]]/[[H.262]],<ref name="history"/> which became the standard video format for [[DVD]] and SD [[digital television]].<ref name="history"/> It was followed by [[MPEG-4 Visual|MPEG-4]] in 1999, and then in 2003 it was followed by [[H.264/MPEG-4 AVC]], which has become the most widely used video coding standard.<ref>{{Cite book |last=Christ |first=Robert D. |url=https://www.worldcat.org/oclc/861797595 |title=The ROV manual : a user guide for remotely operated vehicles |date=2013 |others=Robert L. Wernli |isbn=978-0-08-098291-5 |edition=2nd |location=Oxford |oclc=861797595}}</ref>

The current-generation video coding format is [[HEVC]] (H.265), introduced in 2013. While AVC uses the integer DCT with 4x4 and 8x8 block sizes, HEVC uses integer DCT and [[Discrete sine transform|DST]] transforms with varied block sizes between 4x4 and 32x32.<ref name="apple">{{cite web |last1=Thomson |first1=Gavin |last2=Shah |first2=Athar |year=2017 |title=Introducing HEIF and HEVC |url=https://devstreaming-cdn.apple.com/videos/wwdc/2017/503i6plfvfi7o3222/503/503_introducing_heif_and_hevc.pdf |access-date=5 August 2019 |publisher=[[Apple Inc.]]}}</ref> HEVC is heavily patented, with the majority of patents belonging to [[Samsung Electronics]], [[GE]], [[Nippon Telegraph and Telephone|NTT]] and [[JVC Kenwood]].<ref name="hevc-patents">{{cite web |title=HEVC Patent List |url=https://www.mpegla.com/wp-content/uploads/hevc-att1.pdf |access-date=6 July 2019 |website=[[MPEG LA]]}}</ref> It is currently being challenged by the aiming-to-be-freely-licensed [[AV1]] format. {{As of|2019}}, AVC is by far the most commonly used format for the recording, compression and distribution of video content, used by 91% of video developers, followed by HEVC which is used by 43% of developers.<ref name="Bitmovin">{{cite web |year=2019 |title=Video Developer Report 2019 |url=https://cdn2.hubspot.net/hubfs/3411032/Bitmovin%20Magazine/Video%20Developer%20Report%202019/bitmovin-video-developer-report-2019.pdf |access-date=5 November 2019 |website=[[Bitmovin]]}}</ref>

===Production===
Starting in the late 1970s to the early 1980s, [[video production]] equipment that was digital in its internal workings was introduced. These included [[time base corrector]]s (TBC){{efn|For example, the [[Thomson-CSF]] 9100 Digital Video Processor, an internally all-digital full-frame TBC introduced in 1980.}} and [[digital video effects]] (DVE) units.{{efn|For example the [[Ampex]] ADO, and the [[Nippon Electric Corporation]] (NEC) E-Flex.}} They operated by taking a standard analog [[composite video]] input and digitizing it internally. This made it easier to either correct or enhance the video signal, as in the case of a TBC, or to manipulate and add effects to the video, in the case of a DVE unit. The digitized and processed video information was then converted back to standard analog video for output.

Later on in the 1970s, manufacturers of professional video broadcast equipment, such as [[Robert Bosch GmbH|Bosch]] (through their [[Fernseh]] division) and [[Ampex]] developed prototype digital [[videotape recorder]]s (VTR) in their research and development labs. Bosch's machine used a modified [[Type B videotape|1-inch type B videotape]] transport and recorded an early form of [[CCIR 601]] digital video. Ampex's prototype digital video recorder used a modified [[2-inch quadruplex videotape]] VTR (an Ampex AVR-3) fitted with custom digital video electronics and a special ''octaplex'' 8-head headwheel (regular analog 2" quad machines only used 4 heads). Like standard 2" quad, the audio on the Ampex prototype digital machine, nicknamed ''Annie'' by its developers, still recorded the audio in analog as linear tracks on the tape. None of these machines from these manufacturers were ever marketed commercially.

Digital video was first introduced commercially in 1986 with the Sony [[D-1 (Sony)|D1]] format, which recorded an uncompressed standard definition [[component video]] signal in digital form. Component video connections required 3 cables, but most [[television]] facilities were wired for composite NTSC or PAL video using one cable. Due to this incompatibility the cost of the recorder, D1 was used primarily by large [[television network]]s and other component-video capable video studios.
[[File:A_todo_o_nada_Chile_Studio_(20200130_194157).jpg|thumb|A professional television studio set in Chile]]
In 1988, Sony and Ampex co-developed and released the [[D-2 (video)|D2]] digital videocassette format, which recorded video digitally without compression in [[ITU-601]] format, much like D1. In comparison, D2 had the major difference of encoding the video in composite form to the NTSC standard, thereby only requiring single-cable composite video connections to and from a D2 VCR. This made it a perfect fit for the majority of television facilities at the time. D2 was a successful format in the [[television broadcast]] industry throughout the late '80s and the '90s. D2 was also widely used in that era as the master tape format for mastering [[laserdiscs]].{{efn|Prior to D2, most laserdiscs were mastered using analog [[1" Type C videotape]]}}

D1 & D2 would eventually be replaced by cheaper systems using video compression, most notably Sony's [[Digital Betacam]], that were introduced into the network's [[television studio]]s. Other examples of digital video formats utilizing compression were Ampex's [[DCT (videocassette format)|DCT]] (the first to employ such when introduced in 1992), the industry-standard [[DV (video format)|DV]] and MiniDV and its professional variations, Sony's [[DVCAM]] and Panasonic's [[DVCPRO]], and [[Betacam SX]], a lower-cost variant of Digital Betacam using MPEG-2 compression.<ref>{{Cite book|last=Roger|first=Jennings|title=Special Edition Using Desktop Video|publisher=Que Books, Macmillan Computer Publishing|year=1997|isbn=978-0789702654}}</ref>
[[File:Sony_logo.svg|thumb|The Sony logo, creator of the Betacam]]
One of the first digital video products to run on personal computers was ''PACo: The PICS Animation Compiler'' from The Company of Science & Art in Providence, RI. It was developed starting in 1990 and first shipped in May 1991. PACo could stream unlimited-length video with synchronized sound from a single file (with the ''.CAV'' [[file extension]]) on CD-ROM. Creation required a Mac, and playback was possible on Macs, PCs, and Sun [[SPARCstation]]s.<ref>{{cite news |title=CoSA Lives: The Story of the Company Behind After Effects |newspaper=Motionworks Digital Marketing Agency Melbourne |url=http://www.motionworks.com.au/2009/11/cosa-lives/ |archive-url=https://web.archive.org/web/20110227132422/http://motionworks.com.au/2009/11/cosa-lives/ |archive-date=2011-02-27 |access-date=2009-11-16 |url-status=live }}</ref>

[[QuickTime]], [[Apple Computer]]'s multimedia framework, was released in June 1991. [[Audio Video Interleave]] from [[Microsoft]] followed in 1992. Initial consumer-level content creation tools were crude, requiring an analog video source to be digitized to a computer-readable format. While low-quality at first, consumer digital video increased rapidly in quality, first with the introduction of playback standards such as MPEG-1 and MPEG-2 (adopted for use in television transmission and DVD media), and the introduction of the [[DV (video format)|DV]] tape format allowing recordings in the format to be transferred directly to digital video files using a [[FireWire]] port on an editing computer. This simplified the process, allowing [[non-linear editing system]]s (NLE) to be deployed cheaply and widely on [[desktop computer]]s with no external playback or recording equipment needed.

The widespread adoption of digital video and accompanying compression formats has reduced the [[Bandwidth (computing)|bandwidth]] needed for a [[high-definition video]] signal (with [[HDV]] and [[AVCHD]], as well as several professional formats such as [[XDCAM]], all using less bandwidth than a standard definition analog signal). These savings have increased the number of channels available on [[cable television]] and [[direct broadcast satellite]] systems, created opportunities for [[spectrum reallocation]] of [[terrestrial television]] broadcast frequencies, and made [[tapeless camcorder]]s based on [[flash memory]] possible, among other innovations and efficiencies.

=== Culture ===
Culturally, digital video has allowed video and film to become widely available and popular, beneficial to entertainment, education, and research.<ref name=":1">{{Cite journal|last=Garrett|first=Bradley L.|date=2018|title=Videographic geographies: Using digital video for geographic research|url=http://journals.sagepub.com/doi/10.1177/0309132510388337|journal=Progress in Human Geography|language=en|volume=35|issue=4|pages=521–541|doi=10.1177/0309132510388337|s2cid=131426433|issn=0309-1325}}</ref> Digital video is increasingly common in schools, with students and teachers taking an interest in learning how to use it in relevant ways.<ref>{{Cite journal|last1=Bruce|first1=David L.|last2=Chiu|first2=Ming Ming|date=2015|title=Composing With New Technology: Teacher Reflections on Learning Digital Video|url=http://journals.sagepub.com/doi/10.1177/0022487115574291|journal=Journal of Teacher Education|language=en|volume=66|issue=3|pages=272–287|doi=10.1177/0022487115574291|s2cid=145361658|issn=0022-4871}}</ref> Digital video also has healthcare applications, allowing doctors to track infant heart rates and oxygen levels.<ref>{{Cite journal|last1=Wieler|first1=Matthew E.|last2=Murphy|first2=Thomas G.|last3=Blecherman|first3=Mira|last4=Mehta|first4=Hiral|last5=Bender|first5=G. Jesse|date=2021-03-01|title=Infant heart-rate measurement and oxygen desaturation detection with a digital video camera using imaging photoplethysmography|url=http://dx.doi.org/10.1038/s41372-021-00967-1|journal=Journal of Perinatology|volume=41|issue=7|pages=1725–1731|doi=10.1038/s41372-021-00967-1|pmid=33649437|s2cid=232070728|issn=0743-8346}}</ref>

In addition, the switch from analog to digital video impacted media in various ways, such as in how businesses use cameras for surveillance. [[Closed circuit television]] (CCTV) switched to using [[digital video recorder]]s (DVR), presenting the issue of how to store recordings for evidence collection. Today, digital video is able to be [[Compressed video|compressed]] in order to save storage space.<ref>{{Cite journal|last1=Bruehs|first1=Walter E.|last2=Stout|first2=Dorothy|date=2020|title=Quantifying and Ranking Quality for Acquired Recordings on Digital Video Recorders|url=https://onlinelibrary.wiley.com/doi/10.1111/1556-4029.14307|journal=Journal of Forensic Sciences|language=en|volume=65|issue=4|pages=1155–1168|doi=10.1111/1556-4029.14307|pmid=32134510|s2cid=212417006|issn=0022-1198}}</ref>

=== Digital television ===
[[Digital television]] (DTV) is the production and transmission of digital video from networks to consumers. This technique uses digital encoding instead of analog signals used prior to the 1950s.<ref>{{Cite book|last=Kruger|first=Lennard G.|url=https://www.worldcat.org/oclc/50684535|title=Digital television : an overview|date=2002|publisher=Novinka Books|others=Peter F. Guerrero|isbn=1-59033-502-3|location=New York|oclc=50684535}}</ref> As compared to analog methods, DTV is faster and provides more capabilities and options for data to be transmitted and shared.<ref>{{Cite journal|last=Reimers|first=U.|date=1998|title=Digital video broadcasting|url=https://ieeexplore.ieee.org/document/685371|journal=IEEE Communications Magazine|volume=36|issue=6|pages=104–110|doi=10.1109/35.685371}}</ref>

Digital television's roots are tied to the availability of inexpensive, high-performance [[computers]]. It was not until the 1990s that digital TV became a real possibility.<ref name="benton">{{cite web |date=2008-12-23 |title=The Origins and Future Prospects of Digital Television |url=http://www.benton.org/initiatives/obligations/charting_the_digital_broadcasting_future/sec1 |publisher=[[Benton Foundation]]}}</ref> Digital television was previously not practically feasible due to the impractically high bandwidth requirements of [[uncompressed video]],<ref name="Barbero">{{cite journal |last1=Barbero |first1=M. |last2=Hofmann |first2=H. |last3=Wells |first3=N. D. |date=14 November 1991 |title=DCT source coding and current implementations for HDTV |url=https://tech.ebu.ch/publications/trev_251-barbero |journal=EBU Technical Review |publisher=[[European Broadcasting Union]] |issue=251 |pages=22–33 |access-date=4 November 2019}}</ref> requiring around 200{{nbsp}}[[Mbit/s]] for a [[standard-definition television]] (SDTV) signal,<ref>{{cite web |title=NextLevel signs cable deal - Dec. 17, 1997 |url=https://money.cnn.com/1997/12/17/technology/nextlevel/ |access-date=9 August 2018 |website=money.cnn.com}}</ref><ref>{{cite web |title=TCI faces big challenges - Aug. 15, 1996 |url=https://money.cnn.com/1996/08/15/companies/tci_pkg/ |access-date=9 August 2018 |website=money.cnn.com}}</ref> and over 1{{nbsp}}[[Gbit/s]] for [[high-definition television]] (HDTV).<ref name="Barbero" /><ref>{{cite journal |last1=Barbero |first1=M. |last2=Stroppiana |first2=M. |date=October 1992 |title=Data compression for HDTV transmission and distribution |url=https://ieeexplore.ieee.org/document/193745 |journal=IEE Colloquium on Applications of Video Compression in Broadcasting |pages=10/1–10/5}}</ref>

==Overview ==
Digital video comprises a series of [[digital image]]s displayed in rapid succession. In the context of video, these images are called [[film frame|frames]].{{efn|In fact the still images correspond to frames only in the case of progressive scan video. In interlaced video, they correspond to fields. See {{slink||Interlacing}} for clarification.}} The rate at which frames are displayed is known as the [[frame rate]] and is measured in [[frames per second]]. Every frame is a digital image and so comprises a formation of [[pixel]]s. The color of a pixel is represented by a fixed number of bits of that color where the information of the color is stored within the image.<ref>{{Cite web |last=Winkelman |first=Roy |date=2018 |title=TechEase, What is bit depth? |url=https://etc.usf.edu/techease/win/images/what-is-bit-depth/ |access-date=2022-04-18 |language=en-US}}</ref> For example, 8-bit captures 256 levels per channel, and 10-bit captures 1,024 levels per channel.'''<ref>{{Cite web |last=Steiner |first=Shawn |date=12 December 2018 |title=B&H, 8-Bit, 10-Bit, What Does It All Mean for Your Videos? |url=https://www.bhphotovideo.com/explora/video/tips-and-solutions/8-bit-10-bit-what-does-it-all-mean-your-videos}}</ref>''' The more bits, the more subtle variations of colors can be reproduced. This is called the [[color depth]], or bit depth, of the video.

===Interlacing===
In [[interlaced video]] each ''frame'' is composed of two halves of an image. The first half contains only the odd-numbered lines of a full frame. The second half contains only the even-numbered lines. These halves are referred to individually as ''fields''. Two consecutive fields compose a full frame. If an interlaced video has a frame rate of 30 frames per second the field rate is 60 fields per second, though both part of interlaced video, frames per second and fields per second are separate numbers.
[[File:Pavek_Museum_-_TV_Camera.jpg|thumb|A broadcast television camera at the Pavek Museum in Minnesota.]]

===Bit rate and BPP===
By definition, [[bit rate]] is a measurement of the rate of information content from the digital video stream. In the case of uncompressed video, bit rate corresponds directly to the quality of the video because bit rate is proportional to every property that affects the [[video quality]]. Bit rate is an important property when transmitting video because the transmission link must be capable of supporting that bit rate. Bit rate is also important when dealing with the storage of video because, as shown above, the video size is proportional to the bit rate and the duration. Video compression is used to greatly reduce the bit rate while having little effect on quality.<ref>{{Cite book |last=Acharya |first=Tinku |url=https://www.worldcat.org/oclc/57585202 |title=JPEG2000 standard for image compression: concepts, algorithms and VLSI architectures |date=2005 |publisher=Wiley-Interscience |others=Ping-Sing Tsai |isbn=0-471-65375-6 |location=Hoboken, N.J. |oclc=57585202}}</ref>

Bits per pixel (BPP) is a measure of the efficiency of compression. A true-color video with no compression at all may have a BPP of 24 bits/pixel. [[Chroma subsampling]] can reduce the BPP to 16 or 12 bits/pixel. Applying [[JPEG]] compression on every frame can reduce the BPP to 8 or even 1&nbsp;bits/pixel. Applying video compression algorithms like [[MPEG1]], [[MPEG2]] or [[MPEG4]] allows for fractional BPP values to exist.

====Constant bit rate versus variable bit rate====
BPP represents the ''average'' bits per pixel. There are compression algorithms that keep the BPP almost constant throughout the entire duration of the video. In this case, we also get video output with a [[constant bitrate]] (CBR). This CBR video is suitable for real-time, non-buffered, fixed bandwidth video streaming (e.g. in videoconferencing). Since not all frames can be compressed at the same level, because quality is more severely impacted for scenes of high complexity, some algorithms try to constantly adjust the BPP. They keep the BPP high while compressing complex scenes and low for less demanding scenes.<ref>{{Cite book |last=Weise |first=Marcus |url=https://www.worldcat.org/oclc/1295602475 |title=How video works |date=2013 |others=Diana Weynand |isbn=978-1-136-06982-6 |edition=2nd |location=New York |oclc=1295602475}}</ref> This way, it provides the best quality at the smallest average bit rate (and the smallest file size, accordingly). This method produces a [[variable bitrate]] because it tracks the variations of the BPP.

==Technical overview==
Standard [[film stock]]s typically record at 24 frames per second. For video, there are two frame rate standards: [[NTSC]], at 30/1.001 (about 29.97) frames per second (about 59.94 fields per second), and [[PAL]], 25 frames per second (50 fields per second). Digital video cameras come in two different image capture formats: interlaced and [[progressive scan]]. Interlaced cameras record the image in alternating sets of lines: the odd-numbered lines are scanned, and then the even-numbered lines are scanned, then the odd-numbered lines are scanned again, and so on.

One set of odd or even lines is referred to as a ''field'', and a consecutive pairing of two fields of opposite parity is called a ''frame''. Progressive scan cameras record all lines in each frame as a single unit. Thus, interlaced video captures the scene motion twice as often as progressive video does for the same frame rate. Progressive scan generally produces a slightly sharper image, however, motion may not be as smooth as interlaced video.

Digital video can be copied with no generation loss; which degrades quality in analog systems. However, a change in parameters like frame size, or a change of the digital format can decrease the quality of the video due to [[image scaling]] and [[transcoding]] losses. Digital video can be manipulated and edited on [[non-linear editing]] systems.

Digital video has a significantly lower cost than 35&nbsp;mm film. In comparison to the high cost of [[film stock]], the digital media used for digital video recording, such as [[flash memory]] or [[hard disk drive]] is very inexpensive. Digital video also allows footage to be viewed on location without the expensive and time-consuming chemical processing required by film. Network transfer of digital video makes physical deliveries of tapes and film reels unnecessary. 
[[File:Menger16K 9000p60 Testsequenz 20211231 VP9 fast006.webm|thumb|A short video sequence in native 16K.]]
[[File:Cinemascope_4_perf_35_mm_film.svg|thumb|A diagram of 35 mm film as used in Cinemscope cameras.]]
Digital television (including higher quality [[HDTV]]) was introduced in most developed countries in early 2000s. Today, digital video is used in modern [[mobile phone]]s and [[video conferencing]] systems. Digital video is used for [[Internet]] distribution of media, including [[streaming video]] and [[peer-to-peer]] movie distribution.

Many types of video compression exist for serving digital video over the internet and on optical disks. The file sizes of digital video used for professional editing are generally not practical for these purposes, and the video requires further compression with codecs to be used for recreational purposes.

{{As of|2017}}, the highest [[image resolution]] demonstrated for digital video generation is 132.7 [[megapixel]]s (15360 x 8640 pixels). The highest speed is attained in industrial and scientific [[high-speed camera]]s that are capable of filming 1024x1024 video at up to 1 million frames per second for brief periods of recording.

== Technical properties ==
Live digital video consumes bandwidth. Recorded digital video consumes data storage. The amount of bandwidth or storage required is determined by the frame size, color depth and frame rate. Each pixel consumes a number of bits determined by the color depth. The data required to represent a frame of data is determined by multiplying by the number of pixels in the image. The bandwidth is determined by multiplying the storage requirement for a frame by the frame rate. The overall storage requirements for a program can then be determined by multiplying bandwidth by the duration of the program.

These calculations are accurate for uncompressed video, but due to the relatively high bit rate of uncompressed video, video compression is extensively used. In the case of compressed video, each frame requires only a small percentage of the original bits. This reduces the data or bandwidth consumption by a factor of 5 to 12 times when using [[lossless compression]], but more commonly, [[lossy compression]] is used due to its reduction of data consumption by factors of 20 to 200.<ref>{{Cite web |last=Vatolin |first=Dmitriy |title=Lossless Video Codecs Comparison 2007 |url=https://www.compression.ru/video/codec_comparison/lossless_codecs_2007_en.html |access-date=2022-03-29 |website=www.compression.ru}}</ref>{{Failed verification|date=July 2023}} Note that it is not necessary that all frames are equally compressed by the same percentage. Instead, consider the ''average'' factor of compression for ''all'' the frames taken together.

==Interfaces and cables==
{{broader|Audio and video interfaces and connectors}}

Purpose-built digital video interfaces
*[[Digital component video]]
*[[Digital Visual Interface]] (DVI)
*[[DisplayPort]]
*[[HDBaseT]]
*[[High-Definition Multimedia Interface]] (HDMI)
*[[Unified Display Interface]]

General-purpose interfaces use to carry digital video
*[[FireWire]] (IEEE 1394)
*[[Universal Serial Bus]] (USB)

The following interface has been designed for carrying [[MPEG]]-Transport compressed video:
* [[DVB]]-[[Asynchronous serial communication|ASI]]

Compressed video is also carried using [[User Datagram Protocol|UDP]]-[[Internet Protocol|IP]] over [[Ethernet]]. Two approaches exist for this:
* Using [[Real-time Transport Protocol|RTP]] as a wrapper for video packets as with [[SMPTE 2022]]
* 1–7 [[MPEG transport stream|MPEG Transport Packets]] are placed directly in the [[User Datagram Protocol|UDP]] packet

Other methods of carrying video over IP
* [[Network Device Interface]]
* [[SMPTE 2110]]

==Storage formats==

===Encoding===
{{see also|Video coding format|Video codec}}
*[[CCIR 601]] used for broadcast stations
*[[VC-2]] also known as ''Dirac Pro''
*[[MPEG-4]] good for online distribution of large videos and video recorded to [[flash memory]]
*[[MPEG-2]] used for DVDs, Super-VCDs, and many broadcast television formats
*[[MPEG-1]] used for video CDs
*[[H.261]]
*[[H.263]]
*[[H.264]] also known as ''MPEG-4 Part 10'', or as ''AVC'', used for [[Blu-ray Disc]]s and some broadcast television formats
*[[H.265]] also known as ''MPEG-H Part 2'', or as ''HEVC''
*[[QuickTime File Format|MOV]] used for [[QuickTime]] framework
*[[Theora]] used for video on Wikipedia

===Tapes===
{{main|Videotape}}
* [[Betacam|Betacam SX]], [[MPEG IMX]], [[Digital Betacam]], or DigiBeta — professional video formats by Sony, based on original [[Betamax]] technology
* [[D-VHS]] — MPEG-2 format data recorded on a tape similar to [[S-VHS]][[File:Video_tape_B-Format_(6498660779).jpg|thumb|An archived B-format video tape used in Danish broadcasting.]]
* [[D1 (Sony)|D1]], [[D2 (video format)|D2]], [[D3 (video)|D3]], [[D-5 (Panasonic)|D5]], [[DV (video format)#DVCPRO|D7]], [[D9 (video)|D9]] (also known as Digital-S) — various [[SMPTE]] professional digital video standards
* [[Digital8|D8]] — DV-format data recorded on [[Hi8]]-compatible cassettes; largely a consumer format
* [[DV (video format)|DV]], [[MiniDV]] — used in most of digital videocassette consumer camcorders; designed for high quality and easy editing; can also record high-definition data ([[HDV]]) in MPEG-2 format
* [[DVCAM]], [[DVCPRO]] — used in professional broadcast operations; similar to DV but generally considered more robust; though DV-compatible, these formats have better audio handling.
* [[DVCPRO]]50 and [[DVCPRO]] HD support higher bandwidths as compared to Panasonic's DVCPRO.
* [[HDCAM]] and [[HDCAM SR]] were introduced by Sony as a high-definition alternative to DigiBeta.
* [[MicroMV]] — MPEG-2-format data recorded on a very small, matchbook-sized cassette; obsolete
* [[ProHD]] — name used by JVC for its MPEG-2-based professional camcorders

=== Discs ===
[[File:Blu-ray_disc2.png|thumb|The Blu-ray disc, a type of optical disc used for media storage.]]
{{See also|Optical disc}}
* [[Blu-ray Disc]]
* [[DVD]]
* [[VCD]]

==See also==
{{Div col|colwidth=20em}}
*[[Digital audio]]
*[[Digital cinematography]]
*[[Display aspect ratio]]
*[[Display resolution]]
*[[Index of video-related articles]]
*[[Internet video]]
*[[Online video platform]]
*[[Video coding format]]
*[[Video editing software]]
*[[Webcam]]
{{Div col end}}

==Notes==
{{Notelist}}

==References==
{{reflist}}
{{refbegin}} 
*{{Cite book |last=Sadun |first=Erica |url=https://www.worldcat.org/oclc/630529114 |title=Digital Video Essentials : Shoot, Transfer, Edit, Share. |date=2006 |publisher=John Wiley & Sons |isbn=978-0-470-11319-6 |location=Hoboken |oclc=630529114}}
*{{Cite web |date=December 16, 2016 |title=Digital Video (DV) |url=https://www.techopedia.com/definition/5505/digital-video-dv |access-date=March 23, 2021 |website=Techopedia}}
{{refend}}

==External links==
* [http://www.adamwilt.com/DV.html The DV, DVCAM, & DVCPRO Formats – tech details, FAQ, and links]
* [https://web.archive.org/web/20161021230910/http://www.equasys.de/videoformats.html Standard digital TV and video formats.]

{{Digital systems}}
{{Video storage formats}}

{{DEFAULTSORT:Digital Video}}
[[Category:Film and video technology]]
[[Category:Video signal]]
[[Category:Television terminology]]
[[Category:Audiovisual introductions in 1986]]
[[Category:Film and video terminology]]

[[pl:Digital video]]