Editing Digital video (section)

===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>