Editing Motion compensation (section)

===Motion-compensated DCT===
Practical motion-compensated [[video compression]] emerged with the development of motion-compensated [[Discrete cosine transform|DCT]] (MC DCT) coding,<ref name="Lea">{{cite book |last1=Lea |first1=William |title=Video on demand: Research Paper 94/68 |date=1994 |publisher=[[House of Commons Library]] |url=https://researchbriefings.parliament.uk/ResearchBriefing/Summary/RP94-68 |access-date=20 September 2019 |archive-url=https://web.archive.org/web/20190920082623/https://researchbriefings.parliament.uk/ResearchBriefing/Summary/RP94-68 |archive-date=20 September 2019 |url-status=dead }}</ref> also called block motion compensation (BMC) or DCT motion compensation. This is a hybrid coding algorithm,<ref name="ITU"/> which combines two key [[data compression]] techniques: [[discrete cosine transform]] (DCT) coding<ref name="Lea"/> in the [[spatial dimension]], and predictive motion compensation in the [[temporal dimension]].<ref name="ITU"/> DCT coding is a [[lossy compression|lossy]] block compression [[transform coding]] technique that was first proposed by [[N. Ahmed|Nasir Ahmed]], who initially intended it for [[image compression]], in 1972.<ref name="Ahmed">{{cite journal |last=Ahmed |first=Nasir |author-link=N. Ahmed |title=How I Came Up With the Discrete Cosine Transform |journal=[[Digital Signal Processing (journal)|Digital Signal Processing]] |date=January 1991 |volume=1 |issue=1 |pages=4–5 |doi=10.1016/1051-2004(91)90086-Z |bibcode=1991DSP.....1....4A |url=https://www.scribd.com/doc/52879771/DCT-History-How-I-Came-Up-with-the-Discrete-Cosine-Transform}}</ref>

In 1974, Ali Habibi at the [[University of Southern California]] introduced hybrid coding,<ref>{{cite journal |last1=Habibi |first1=Ali |title=Hybrid Coding of Pictorial Data |journal=IEEE Transactions on Communications |date=1974 |volume=22 |issue=5 |pages=614–624 |doi=10.1109/TCOM.1974.1092258}}</ref><ref>{{cite journal |last1=Chen |first1=Z. |last2=He |first2=T. |last3=Jin |first3=X. |last4=Wu |first4=F. |title=Learning for Video Compression |journal=IEEE Transactions on Circuits and Systems for Video Technology |volume=30 |issue=2 |pages=566–576 |doi=10.1109/TCSVT.2019.2892608 |arxiv=1804.09869 |year=2020 |s2cid=13743007 }}</ref> which combines predictive coding with transform coding.<ref name="ITU"/><ref>{{cite book |last1=Ohm |first1=Jens-Rainer |title=Multimedia Signal Coding and Transmission |date=2015 |publisher=Springer |isbn=9783662466919 |pages=364 |url=https://books.google.com/books?id=e7xnBwAAQBAJ&pg=PA364}}</ref> However, his algorithm was initially limited to [[intra-frame]] coding in the spatial dimension. In 1975, John A. Roese and Guner S. Robinson extended Habibi's hybrid coding algorithm to the temporal dimension, using transform coding in the spatial dimension and predictive coding in the temporal dimension, developing [[inter-frame]] motion-compensated hybrid coding.<ref name="ITU"/><ref name="Roese">{{cite journal |last1=Roese |first1=John A. |last2=Robinson |first2=Guner S. |editor-first1=Andrew G. |editor-last1=Tescher |title=Combined Spatial And Temporal Coding Of Digital Image Sequences |journal=Efficient Transmission of Pictorial Information |date=30 October 1975 |volume=0066 |pages=172–181 |doi=10.1117/12.965361 |bibcode=1975SPIE...66..172R |publisher=International Society for Optics and Photonics|s2cid=62725808 }}</ref> For the spatial transform coding, they experimented with the DCT and the [[fast Fourier transform]] (FFT), developing inter-frame hybrid coders for both, and found that the DCT is the most efficient due to its reduced complexity, capable of compressing image data down to 0.25-[[bit]] per [[pixel]] for a [[videotelephone]] scene with image quality comparable to an intra-frame coder requiring 2-bit per pixel.<ref>{{cite book |last1=Huang |first1=T. S. |title=Image Sequence Analysis |date=1981 |publisher=[[Springer Science & Business Media]] |isbn=9783642870378 |page=29 |url=https://books.google.com/books?id=bAirCAAAQBAJ&pg=PA29}}</ref><ref name="Roese"/>

In 1977, Wen-Hsiung Chen developed a fast DCT algorithm with C.H. Smith and S.C. Fralick.<ref>{{cite journal |last1=Chen |first1=Wen-Hsiung |last2=Smith |first2=C. H. |last3=Fralick |first3=S. C. |title=A Fast Computational Algorithm for the Discrete Cosine Transform |journal=[[IEEE Transactions on Communications]] |date=September 1977 |volume=25 |issue=9 |pages=1004–1009 |doi=10.1109/TCOM.1977.1093941}}</ref> In 1979, [[Anil K. Jain (electrical engineer, born 1946)|Anil K. Jain]] and Jaswant R. Jain further developed motion-compensated DCT video compression,<ref>{{cite book |last1=Cianci |first1=Philip J. |title=High Definition Television: The Creation, Development and Implementation of HDTV Technology |date=2014 |publisher=McFarland |isbn=9780786487974 |page=63 |url=https://books.google.com/books?id=0mbsfr38GTgC&pg=PA63}}</ref><ref name="ITU"/> also called block motion compensation.<ref name="ITU"/> This led to Chen developing a practical video compression algorithm, called motion-compensated DCT or adaptive scene coding, in 1981.<ref name="ITU"/> Motion-compensated DCT later became the standard coding technique for video compression from the late 1980s onwards.<ref name="Ghanbari">{{cite book |last1=Ghanbari |first1=Mohammed |title=Standard Codecs: Image Compression to Advanced Video Coding |date=2003 |publisher=[[Institution of Engineering and Technology]] |isbn=9780852967102 |pages=1–2 |url=https://books.google.com/books?id=7XuU8T3ooOAC&pg=PA1}}</ref><ref name="Li"/>

The first digital [[video coding standard]] was [[H.120]], developed by the [[ITU-T|CCITT]] (now ITU-T) in 1984.<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 used motion-compensated DPCM coding,<ref name="ITU"/> which was inefficient for video coding,<ref name="Ghanbari"/> and H.120 was thus impractical due to low performance.<ref name="history"/> The [[H.261]] standard was developed in 1988 based on motion-compensated DCT compression,<ref name="Ghanbari"/><ref name="Li"/> and it was the first practical video coding standard.<ref name="history"/> Since then, motion-compensated DCT compression has been adopted by all the major video coding standards (including the [[H.26x]] and [[MPEG]] formats) that followed.<ref name="Ghanbari"/><ref name="Li"/>