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'''High Efficiency Video Coding tiers and levels''' are constraints that define a [[High Efficiency Video Coding]] (HEVC) bitstream in terms of maximum bit rate, maximum luma sample rate, maximum luma picture size, minimum compression ratio, maximum number of slices allowed, and maximum number of tiles allowed.<ref name=OverviewHEVCIEEE2012>{{cite news |title=Overview of the High Efficiency Video Coding (HEVC) Standard |author=G.J. Sullivan |author2=J.-R. Ohm |author3=W.-J. Han |author4=T. Wiegand |publisher=IEEE Trans. on Circuits and Systems for Video Technology |url=http://iphome.hhi.de/wiegand/assets/pdfs/2012_12_IEEE-HEVC-Overview.pdf |format=PDF |date=2012-05-25 |accessdate=2012-09-14}}</ref><ref name=HEVCdraft10HEVCITURecommendationH265>{{cite news |title=HighH.265 Efficiency: VideoHigh Codingefficiency (HEVC)video text specification draft 10 (for FDIS & Consent)coding |publisher=JCT-VCITU |url=http://phenixwww.it-sudparisitu.euint/jctrec/doc_end_user/current_documentT-REC-H.php?id=7243 265|date=2013-0106-1707 |accessdate=2013-0106-2407}}</ref> Lower tiers are more constrained than higher tiers and lower levels are more constrained than higher levels.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/>
==Tiers==
The January 2013 HEVC draftstandard defines two tiers: '''Main''' and '''High'''.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> The Main tier is a lower tier than the High tier.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> The tiers were made to deal with applications that differ in terms of their maximum bit rate.<ref name=OverviewHEVCIEEE2012/> The Main tier was designed for most applications while the High tier was designed for very demanding applications.<ref name=OverviewHEVCIEEE2012/>
==Levels==
The January 2013 HEVC draftstandard defines thirteen levels.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> A level is a set of constraints for a bitstream.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> For levels below level 4 only the Main tier is allowed.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> A decoder that conforms to a given tier/level is required to be capable of decoding all bitstreams that are encoded for that tier/level and for all lower tiers/levels.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/>
{| class="wikitable" cellpadding="1" cellspacing="1" style="text-align:right; "
|+ Tiers and levels with maximum property values<ref name=HEVCdraft10HEVCITURecommendationH265/>
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!rowspan="2"| Level
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:{{note label|MaxFrameRate|A|A}} The maximum frame rate supported by HEVC is 300 [[frames per second]] (fps).<ref name=HEVCdraft10HEVCITURecommendationH265/>
:{{note label|MaxDpbSize|B|B}} The MaxDpbSize, maximum number of pictures in the [[High Efficiency Video Coding#Decoded picture buffer|decoded picture buffer]], for the maximum luma picture size of that level is 6 for all levels.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/> The MaxDpbSize can increase to a maximum of 16 frames if the luma picture size of the video is smaller than the maximum luma picture size of that level in incremental steps of 4/3×, 2×, or 4×.<ref name=OverviewHEVCIEEE2012/><ref name=HEVCdraft10HEVCITURecommendationH265/>
:{{note label|MinCR|C|C}} The MinCR, minimum compression ratio, for that level.<ref name=HEVCdraft10HEVCITURecommendationH265/>
:{{note label|Slices|D|D}} The maximum number of slice segments is the number of slices allowed per picture at both the maximum resolution and maximum frame rate.<ref name=HEVCdraft10HEVCITURecommendationH265/><ref name=HEVCOctober2012K0201>{{cite news |title=AHG9: on number of slices constraint |author=Minhua Zhou |publisher=JCT-VC |url=http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=6572 |date=2012-10-01 |accessdate=2012-11-27}}</ref>
:{{note label|Tiles|E|E}} The maximum number of tiles allowed per picture.<ref name=HEVCdraft10HEVCITURecommendationH265/> The maximum number of tiles allowed per second is the maximum number of tiles allowed per picture times 120.<ref name=HEVCdraft10HEVCITURecommendationH265/><ref name=HEVCOctober2012K0202>{{cite news |title=AHG9: on number of tiles constraint |author=Minhua Zhou |publisher=JCT-VC |url=http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=6573 |date=2012-10-01 |accessdate=2012-11-27}}</ref>
==See also==
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