ISO/IEC 23008-2:2025

International
Standard
ISO/IEC 23008-2
Sixth edition
Information technology — High
2025-03
efficiency coding and media
delivery in heterogeneous
environments —
Part 2:
High efficiency video coding
Technologies de l'information — Codage à haute efficacité et
livraison des medias dans des environnements hétérogènes —
Partie 2: Codage vidéo à haute efficacité
Reference number
© ISO/IEC 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO/IEC 2025 – All rights reserved
ii
All rights reserved. Unless otherwise specified, or required in the context of its implementation,
no part of this publication may be reproduced or utilized otherwise in any form or by any means,
electronic or mechanical, including photocopying, or posting on the internet or an intranet,
without prior written permission. Permission can be requested from either ISO at the address
below or ISO's member body in the country of the requester.
ISO Copyright Office
CP 401 • CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland.
© ISO/IEC 2025 – All rights reserved
ii
Contents Page
Foreword . vii
Introduction . ix
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 22
5 Conventions. 24
5.1 General . 24
5.2 Arithmetic operators . 24
5.3 Logical operators . 25
5.4 Relational operators . 25
5.5 Bit-wise operators . 25
5.6 Assignment operators. 26
5.7 Range notation . 26
5.8 Mathematical functions . 26
5.9 Order of operation precedence . 27
5.10 Variables, syntax elements, and tables . 28
5.11 Text description of logical operations . 29
5.12 Processes . 31
6 Bitstream and picture formats, partitionings, scanning processes, and neighbouring
relationships . 31
6.1 Bitstream formats . 31
6.2 Source, decoded, and output picture formats . 31
6.3 Partitioning of pictures, slices, slice segments, tiles, CTUs, and CTBs . 34
6.3.1 Partitioning of pictures into slices, slice segments, and tiles . 34
6.3.2 Block and quadtree structures . 36
6.3.3 Spatial or component-wise partitionings . 37
6.4 Availability processes . 37
6.4.1 Derivation process for z-scan order block availability . 37
6.4.2 Derivation process for prediction block availability . 38
6.5 Scanning processes . 40
6.5.1 CTB raster and tile scanning conversion process . 40
6.5.2 Z-scan order array initialization process . 41
6.5.3 Up-right diagonal scan order array initialization process . 41
6.5.4 Horizontal scan order array initialization process . 42
6.5.5 Vertical scan order array initialization process . 42
© ISO/IEC 2025 – All rights reserved
iii
6.5.6 Traverse scan order array initialization process . 43
7 Syntax and semantics . 43
7.1 Method of specifying syntax in tabular form . 43
7.2 Specification of syntax functions and descriptors . 44
7.3 Syntax in tabular form . 46
7.3.1 NAL unit syntax . 46
7.3.2 Raw byte sequence payloads, trailing bits, and byte alignment syntax . 47
7.3.3 Profile, tier and level syntax . 56
7.3.4 Scaling list data syntax . 59
7.3.5 Supplemental enhancement information message syntax . 60
7.3.6 Slice segment header syntax . 60
7.3.7 Short-term reference picture set syntax . 65
7.3.8 Slice segment data syntax . 66
7.4 Semantics . 81
7.4.1 General . 81
7.4.2 NAL unit semantics . 81
7.4.3 Raw byte sequence payloads, trailing bits, and byte alignment semantics . 92
7.4.4 Profile, tier, and level semantics . 115
7.4.5 Scaling list data semantics . 119
7.4.6 Supplemental enhancement information message semantics . 122
7.4.7 Slice segment header semantics . 122
7.4.8 Short-term reference picture set semantics . 132
7.4.9 Slice segment data semantics . 135
8 Decoding process . 151
8.1 General decoding process . 151
8.1.1 General . 151
8.1.2 CVSG decoding process . 151

8.1.3 Decoding process for a coded picture with nuh_layer_id equal to 0 . 152
8.2 NAL unit decoding process . 154
8.3 Slice decoding process . 155
8.3.1 Decoding process for picture order count . 155
8.3.2 Decoding process for reference picture set . 156
8.3.3 Decoding process for generating unavailable reference pictures . 161
8.3.4 Decoding process for reference picture lists construction . 162
8.3.5 Decoding process for collocated picture and no backward prediction flag . 163
8.4 Decoding process for coding units coded in intra prediction mode . 164
8.4.1 General decoding process for coding units coded in intra prediction mode . 164
© ISO/IEC 2025 – All rights reserved
iv
8.4.2 Derivation process for luma intra prediction mode . 169
8.4.3 Derivation process for chroma intra prediction mode . 171
8.4.4 Decoding process for intra blocks . 172
8.5 Decoding process for coding units coded in inter prediction mode . 185
8.5.1 General decoding process for coding units coded in inter prediction mode . 185
8.5.2 Inter prediction process . 186
8.5.3 Decoding process for prediction units in inter prediction mode . 190
8.5.4 Decoding process for the residual signal of coding units coded in inter
prediction mode .22 3
8.6 Scaling, transformation and array construction process prior to deblocking filter
process .
...