Advanced Video Coding: Difference between revisions

Revision as of 08:09, 5 June 2025

Revision as of 06:14, 8 June 2025

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** Weighted prediction, allowing an encoder to specify the use of a scaling and offset when performing motion compensation, and providing a significant benefit in performance in special cases—such as fade-to-black, fade-in, and cross-fade transitions. This includes implicit weighted prediction for B-frames, and explicit weighted prediction for P-frames.

* Spatial prediction from the edges of neighboring blocks for [[Intra-frame|"intra"]] coding, rather than the "DC"-only prediction found in MPEG-2 Part 2 and the transform coefficient prediction found in H.263v2 and MPEG-4 Part 2. This includes luma prediction block sizes of 16×16, 8×8, and 4×4 (of which only one type can be used within each [[macroblock]]).

* Integer [[discrete cosine transform]] (integer DCT),<ref name="Wang">{{cite journal |last1=Wang |first1=Hanli |last2=Kwong |first2=S. |last3=Kok |first3=C. |s2cid=2060937 |title=Efficient prediction algorithm of integer DCT coefficients for H.264/AVC optimization |journal=IEEE Transactions on Circuits and Systems for Video Technology |date=2006 |volume=16 |issue=4 |pages=547–552 |doi=10.1109/TCSVT.2006.871390}}</ref><ref name="Stankovic">{{cite journal |last1=Stanković |first1=Radomir S. |last2=Astola |first2=Jaakko T. |title=Reminiscences of the Early Work in DCT: Interview with K.R. Rao |journal=Reprints from the Early Days of Information Sciences |date=2012 |volume=60 |page=17 |url=http://ticsp.cs.tut.fi/reports/ticsp-report-60-reprint-rao-corrected.pdf#page=18 |access-date=13 October 2019}}</ref><ref>{{cite book |last1=Kwon |first1=Soon-young |last2=Lee |first2=Joo-kyong |last3=Chung |first3=Ki-dong |title=Image Analysis and Processing – ICIAP 2005 |chapter=Half-Pixel Correction for MPEG-2/H.264 Transcoding |series=Lecture Notes in Computer Science |date=2005 |volume=3617 |pages=576–583 |doi=10.1007/11553595_71 |publisher=Springer Berlin Heidelberg|isbn=978-3-540-28869-5 |doi-access=free }}</ref> a type of discrete cosine transform (DCT)<ref name="Stankovic"/> where the transform is an integer approximation of the standard DCT.<ref name="Britanak2010">{{cite book |last1=Britanak |first1=Vladimir |last2=Yip |first2=Patrick C. |last3=Rao |first3=K. R. |author3-link=K. R. Rao |title=DiPropertiesDiscrete Cosine and Sine Transforms: General Properties, Fast Algorithms and Integer Approximations |date=2010 |publisher=[[Elsevier]] |isbn=9780080464640 |pages=ix, xiii, 1, 141–304 |url=https://books.google.com/books?id=iRlQHcK-r_kC&pg=PA141}}</ref> It has selectable block sizes<ref name="apple">{{cite web |last1=Thomson |first1=Gavin |last2=Shah |first2=Athar |title=Introducing HEIF and HEVC |url=https://devstreaming-cdn.apple.com/videos/wwdc/2017/503i6plfvfi7o3222/503/503_introducing_heif_and_hevc.pdf |publisher=[[Apple Inc.]] |year=2017 |access-date=5 August 2019}}</ref> and exact-match integer computation to reduce complexity, including:

** An exact-match integer 4×4 spatial block transform, allowing precise placement of [[residual frame|residual]] signals with little of the "[[ringing artifact|ringing]]" often found with prior codec designs. It is similar to the standard DCT used in previous standards, but uses a smaller block size and simple integer processing. Unlike the cosine-based formulas and tolerances expressed in earlier standards (such as H.261 and MPEG-2), integer processing provides an exactly specified decoded result.

** An exact-match integer 8×8 spatial block transform, allowing highly correlated regions to be compressed more efficiently than with the 4×4 transform. This design is based on the standard DCT, but simplified and made to provide exactly specified decoding.

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[[Category:ITU-T H Series Recommendations|H.264]]

[[Category:H.26x]]

[[Category:ISO standstandards]]

[[Category:MPEG-4|MPEG-4 Part 10]]

[[Category:IEC standards]]