ISO/IEC 23090-5:2021

INTERNATIONAL ISO/IEC
STANDARD 23090-5
First edition
2021-06
Information technology — Coded
representation of immersive media —
Part 5:
Visual volumetric video-based coding
(V3C) and video-based point cloud
compression (V-PCC)
Technologie de l'information — Représentation codée de média
immersifs —
Partie 5: Codage basé sur la vidéo volumétrique (V3C) et compression
de nuage de points basée sur la vidéo (V-PCC)
Reference number
©
ISO/IEC 2021
© ISO/IEC 2021
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ii © ISO/IEC 2021 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Abbreviated terms .15
5 Conventions .16
5.1 General .16
5.2 Arithmetic operators .16
5.3 Logical operators .16
5.4 Relational operators .17
5.5 Bit-wise operators.17
5.6 Assignment operators .18
5.7 Other operators .18
5.8 Mathematical functions .18
5.9 Order of operation precedence .19
5.10 Variables, syntax elements and tables .19
5.11 Text description of logical operations .21
5.12 Processes .22
6 Overall V3C characteristics, decoding operations and post-decoding processes .23
6.1 V3C characteristics .23
6.2 V3C bitstream characteristics, decoding operations and post-decoding processes .25
7 Bitstream format, partitioning and scanning processes .26
7.1 General .26
7.2 V3C bitstream formats .26
7.3 NAL bitstream formats .27
7.4 Partitioning of atlas frames into tiles .27
7.5 Tile partition scanning process .28
8 Syntax and semantics .29
8.1 Method of specifying syntax in tabular form .29
8.2 Specification of syntax functions and descriptors .30
8.3 Syntax in tabular form .32
8.3.1 General.32
8.3.2 V3C unit syntax .33
8.3.3 Byte alignment syntax .34
8.3.4 V3C parameter set syntax .35
8.3.5 NAL unit syntax .38
8.3.6 Raw byte sequence payloads, trailing bits and byte alignment syntax .38
8.3.7 Atlas tile data unit syntax .44
8.3.8 Supplemental enhancement information message syntax.48
8.4 Semantics .49
8.4.1 General.49
8.4.2 V3C unit semantics.49
8.4.3 Byte alignment semantics .51
8.4.4 V3C parameter set semantics .51
8.4.5 NAL unit semantics .57
8.4.6 Raw byte sequence payloads, trailing bits and byte alignment semantics .66
8.4.7 Atlas tile data unit semantics .79
8.4.8 Supplemental enhancement information message semantics .87
9 Decoding process .87
9.1 General decoding process .87
© ISO/IEC 2021 – All rights reserved iii

9.2 Atlas data decoding process .88
9.2.1 General atlas data decoding process .88
9.2.2 Decoding process for a coded atlas frame .89
9.2.3 Atlas NAL unit decoding process .90
9.2.4 Atlas tile header decoding process .90
9.2.5 Decoding process for patch data units .95
9.2.6 Decoding process of the block to patch map .110
9.2.7 Conversion of tile level patch information to atlas level patch information .111
9.3 Occupancy video decoding process .113
9.4 Geometry video decoding process .114
9.5 Attribute video decoding process .116
9.6 Sub-bitstream extraction process .119
9.6.1 General.119
9.6.2 V3C unit extraction .119
9.6.3 NAL unit extraction process .120
10 Pre-reconstruction process .120
11 Reconstruction process .120
12 Post-reconstruction process .120
13 Adaptation process .120
14 Parsing process .121
14.1 General .121
14.2 Parsing process for 0-th order Exp-Golomb codes .121
14.2.1 General.121
14.2.2 Mapping process for signed Exp-Golomb codes .122
Annex A (normative) Profiles, tiers and levels .123
Annex B (normative) Post-decoding conversion to nominal video formats .137
Annex C (normative) V3C sample stream format .158
Annex D (normative) NAL sample stream format .160
Annex E (normative) Atlas hypothetical reference decoder .162
Annex F (normative) Supplemental enhancement information .179
Annex G (normative) Volumetric usability information .236
Annex H (normative) Video-based point cloud coding .247
Bibliography .331
iv © ISO/IEC 2021 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that
are members of ISO or IEC participate in the development of International Standards through
technical committees established by the respective organization to deal with particular fields of
technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC
list of patent declarations received (see http:// patents .iec .ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO/IEC 23090 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO/IEC 2021 – All rights reserved v

Introduction
Advances in 3D capturing and rendering technologies have unleashed a new wave of innovation in
virtual/augmented/mixed reality (VR/AR/MR) content creation and communication, of which visual
volumetric video is an integral part.
Visual volumetric video, a sequence of visual volumetric frames, if uncompressed, can be represented
by a large amount of data, which can be costly in terms of storage and transmission. This has led to the
need for a high coding efficiency standard for the compression of visual volumetric data.
Visual volumetric frames can be coded by converting the 3D volumetric information into a collection of
2D images and associated data. The converted 2D images can be coded using widely available video and
image coding specifications, such as ISO/IEC 14496-10 and ISO/IEC 23008-2 and the associated data
can be coded with mechanisms specified in this document. The coded images and the associated data
can then be decoded and used to reconstruct the 3D volumetric information. This document specifies
a generic mechanism for visual volumetric video coding, i.e. visual volumetric video-based coding. The
generic mechanism can be used by applications targeting volumetric content, such as point clouds,
immersive video with depth, mesh representations of visual volumetric frames, etc.
In addition to the generic mechanism of coding volumetric content, this document specifies one of the
applications of visual volumetric video-based coding targeting point cloud representations of visual
volumetric frames. In a point cloud sequence, each point cloud frame contains a collection of points.
Each point has a 3D position, i.e., geometry information, and each point can also be associated with a
number of attributes, such as colour, reflectance, surface normal, etc.
The International Organization for Standardization (ISO) and International Electrotechnical
Commission (IEC) draw attention to the fact that it is claimed that compliance with this document may
involve the use of a patent.
ISO and IEC take no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO and IEC that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this
respect, the statement of the holder of this patent right is registered with ISO and IEC. Information may
be obtained from the patent database available at www .iso .org/ patents.
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights other than those in the patent database. ISO and IEC shall not be held responsible for
identifying any or all such patent rights.
vi © ISO/IEC 2021 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 23090-5:2021(E)
Information technology — Coded representation of
immersive media —
Part 5:
Visual volumetric video-based coding (V3C) and video-
based point cloud compression (V-PCC)
1 Scope
This document specifies the syntax, semantics and decoding for visual volumetric media using
video-based coding methods. This document also specifies processes that can be needed for
reconstruction of visual volumetric media, which can also include additional processes such as
post-decoding, pre-reconstruction, post-reconstruction and adaptation.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitute requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
IEEE 754-2019, IEEE Standard for Floating-Point Arithmetic
IETF RFC 1321The MD5 Message-Digest Algorithm
IETF RFC 5646Tags for Identifying Languages
ISO/IEC 10646, Information technology — Universal Coded Character Set (UCS)
ISO/IEC 14496-10:2020, Information technology — Coding of audio-visual objects — Part 10: Advanced
Video Coding
ISO/IEC 14496-12, Information technology — Coding of audio-visual objects — Part 12: ISO base media
file format
ISO/IEC 14496-15, Information technology — Coding of audio-visual objects — Part 15: Carriage of
network abstraction layer (NAL) unit structured video in the ISO base media file format
ISO/IEC 23008-2:2020, Information technology — High efficiency coding and media delivery in
heterogeneous environments — Part 2: High efficiency video coding
ISO/IEC 23090-3, Information technology — Coded representation of immersive media — Part 3: Versatile
video coding
ISO/IEC 23091-2, Coding-independent code points for video signal type identification
Rec. ITU-T T.35:2000, Procedure for the allocation of ITU-T defined codes for non standard facilities
Rec. ITU-T H.271:2006, Video back-channel messages for conveyance of status information and requests
from a video receiver to a video sender
© ISO/IEC 2021 – All rights reserved 1

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
3D bounding box
volume defined as a cuboid solid having six rectangular faces placed at right angles
3.2
associated non-ACL NAL unit
non-ACL NAL unit (3.78) that is associated with an ACL NAL unit (3.6) for the purpose of decoding or
other operations specified by this document
3.3
associated ACL NAL unit
preceding ACL NAL unit (3.6) in decoding order for a non-ACL NAL unit (3.78) with nal_unit_type equal
to NAL_EOS, NAL_EOB, NAL_FD, NAL_SUFFIX_NSEI, or NAL_SUFFIX_ESEI, or in the ranges of NAL_
RSV_NACL_48.NAL_RSV_NACL_52 or NAL_UNSPEC_53.NAL_UNSPEC_63; or otherwise the next ACL
NAL unit (3.6) in decoding order
3.4
atlas
collection of 2D bounding boxes and their associated information placed onto a rectangular frame and
corresponding to a volume in 3D space on which volumetric data is rendered
3.5
atlas bitstream
sequence of bits that forms the representation of atlas frames (3.8) and associated data forming one or
more CASs (3.36)
3.6
atlas coding layer NAL unit
ACL NAL unit
collective term for coded atlas tile layer NAL units (3.76) and the subset of NAL units (3.76) that have
reserved values of nal_unit_type that are classified as being of type class equal to ACL in this document
3.7
atlas coordinates
two scalars (x, y) with finite precision and dynamic range that indicate the location of an atlas sample
relative to the top left corner of an atlas frame, with x and y indicating the horizontal and vertical
direction, respectively
3.8
atlas frame
2D rectangular array of atlas samples onto which patches (3.85) are projected and additional
information related to the patches (3.85), corresponding to a volumetric frame (3.138)
3.9
atlas frame parameter set
AFPS
syntax structure (3.120) containing syntax elements (3.119) that apply to zero or more entire coded atlas
frames (3.8) as determined by the content of a syntax element (3.119) found in each tile header
2 © ISO/IEC 2021 – All rights reserved

3.10
atlas sample
position on the rectangular frame onto which patches (3.85) that are associated with an atlas (3.4) are
projected
3.11
atlas sequence
collection of atlas frames (3.8)
3.12
atlas sequence parameter set
ASPS
syntax structure (3.120) containing syntax elements (3.119) that apply to zero or more entire coded atlas
sequences (3.35) as determined by the content of a syntax element (3.119) found in the AFPS referred to
by a syntax element found in each tile header
3.13
atlas sub-bitstream
extracted sub-bitstream (3.108) from the V3C bitstream (3.128) containing a part of an atlas NAL
bitstream
3.14
atlas unit
set of NAL units (3.76) that contain all ACL NAL units (3.6) of a coded atlas (3.34) and their associated
non-ACL NAL units (3.2)
3.15
attribute
scalar or vector property optionally associated with each point in a volumetric frame (3.138) such as
colour, reflectance, surface normal, transparency, material ID, etc.
3.16
attribute access unit
collection of attribute maps (3.18) and auxiliary attribute frames, if available, for a specific attribute
(3.15) that correspond to the same time instance
3.17
attribute frame
2D rectangular array created through the aggregation of patches (3.85) containing values of a specific
attribute (3.15)
3.18
attribute map
attribute frame (3.17) containing attribute patch (3.85) information projected at a particular depth
indicated by the corresponding geometry map (3.59)
3.19
auxiliary attribute frame
2D rectangular array that is associated with RAW patches (3.103) and EOM patches (3.51), and contains
values of a specific attribute (3.15)
3.20
auxiliary geometry frame
2D rectangular array that is associated with RAW patches (3.103) and contains geometry (3.56) values
3.21
auxiliary video component
video component (3.125) indicated as being of auxiliary type through an appropriate flag in the VPS
(3.134) and containing data only associated with RAW patches (3.103) or EOM patches (3.51), or both
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3.22
auxiliary video sub-bitstream
video sub-bitstream (3.127) indicated as being of auxiliary type through an appropriate flag in the VPS
(3.134) and containing data only associated with RAW patches (3.103) or EOM patches (3.51), or both
3.23
bitstream
ordered series of bits that forms the coded representation of the data
3.24
byte
sequence of 8 bits, within which, when written or read as a sequence of bit values, the left-most and
right-most bits represent the most and least significant bits, respectively
3.25
broken link access access unit
BLA access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a BLA coded atlas (3.26)
3.26
broken link access coded atlas
BLA coded atlas
IRAP coded atlas (3.73) frame for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_BLA_W_
LP, NAL_GBLA_W_LP, NAL_BLA_W_RADL NAL_GBLA_W_RADL, NAL_BLA_N_LP or NAL_GBLA_N_LP.
Note 1 to entry: A BLA coded atlas does not use inter prediction in its decoding process, and could be the first
coded atlas in the bitstream in decoding order, or could appear later in the bitstream. Each BLA coded atlas
begins a new CAS, and has the same effect on the decoding process as an instantaneous decoding refresh (IDR)
coded atlas. However, a BLA coded atlas contains syntax elements that specify a non-empty DAB. When a BLA
coded atlas frame for which each ACL NAL unit has nal_unit_type equal to NAL_BLA_W_LP or NAL_GBLA_W_LP,
it may have associated random access skipped leading (RASL) coded atlas frames, which are not output by the
decoder and may not be decodable, as they may contain references to atlas frames that are not present in the
bitstream. When a BLA coded atlas frame for which each ACL NAL unit has nal_unit_type equal to NAL_BLA_W_
LP or NAL_GBLA_W_LP, it may also have associated RADL coded atlas frames, which are specified to be decoded.
When a BLA coded atlas frame for which each ACL NAL unit has nal_unit_type equal to NAL_BLA_W_RADL or
NAL_GBLA_W_RADL, it does not have associated RASL coded atlas frames but may have associated random
access decodable leading (RADL) coded atlas frames. When a BLA coded atlas frame for which each ACL NAL unit
has nal_unit_type equal to NAL_BLA_N_LP or NAL_GBLA_N_LP, it does not have any associated leading coded
atlas frames.
3.27
byte-aligned
positioned as an integer multiple of 8 bits from the position of the first bit in the bitstream (3.23)
3.28
byte-aligned position
position in a bitstream (3.23) that is byte-aligned (3.27)
3.29
byte-aligned byte
byte (3.24) that appears in a position in a bitstream (3.23) that is byte-aligned (3.27)
3.30
Cartesian coordinates
three scalars (x, y, z) with finite precision and dynamic range that indicate the location of a point relative
to a fixed reference point (the origin)
3.31
clean random access access unit
CRA access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a CRA coded atlas (3.32)
4 © ISO/IEC 2021 – All rights reserved

3.32
clean random access coded atlas
CRA coded atlas
IRAP coded atlas (3.73)for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_CRA or
NAL_GCRA
Note 1 to entry: A CRA coded atlas does not use inter prediction in its decoding process, and could be the first
coded atlas in the bitstream in decoding order, or could appear later in the bitstream. A CRA coded atlas could
have associated RADL or RASL coded atlas frames. When a CRA coded atlas has NoOutputBeforeRecoveryFlag
equal to 1, the associated RASL coded atlas frames are not output by the decoder, because they might not be
decodable, as they could contain references to coded atlas frames that are not present in the bitstream.
3.33
codec
specification, device, or system that specifies or uses well defined instructions for encoding or decoding
a digital data, i.e. image or video, stream or signal
3.34
coded atlas
coded atlas frame
coded representation of an atlas (3.4)
3.35
coded atlas access unit
set of atlas NAL units (3.76) that are associated with each other according to a specified classification
rule, are consecutive in decoding order, and contain all atlas NAL units (3.76) pertaining to one
particular output time
3.36
coded atlas sequence
CAS
sequence of coded atlas access units (3.35), in decoding order, of an IRAP coded atlas access unit (3.74),
followed by zero or more coded atlas access units (3.35) that are not IRAP coded atlas access units (3.74),
including all subsequent access units (3.35) up to but not including any subsequent coded atlas access
unit (3.35) that is an IRAP coded atlas access unit (3.74)
3.37
coded volumetric frame
collection of coded representations of an atlas (3.4), occupancy (3.83), geometry access unit (3.57), and,
for each available attribute (3.15), attribute access unit (3.16), pertaining to one particular time instance
3.38
coded V3C sequence
CVS
sequence of V3C sub-bitstreams (3.133) identified and separated by appropriate delimiters, required to
start with a VPS (3.134), included in at least one V3C unit (3.135) or provided through external means,
and contains one or more V3C units that can be factored into V3C composition units (3.131), where the
first V3C composition unit is a V3C IRAP composition unit (3.132)
3.39
coded representation
data element as represented in its coded form
3.40
coded sub-bitstream sequence
sub-bitstream IRAP composition unit (3.110) followed by zero or more sub-bitstream composition
units (3.109)
3.41
coded V3C component
coded representation of a V3C component (3.129)
© ISO/IEC 2021 – All rights reserved 5

3.42
component bitstream
bitstream (3.23) representing a V3C component (3.129)
3.43
component sub-bitstream
portion of component bitstream (3.42)
3.44
composition time
time or time period at which a frame needs to be composed, used for reconstruction, or presented
3.45
composition time index
index to an ordered list of composition times (3.44)
3.46
composition unit
partition of a bitstream (3.23) that has a certain composition time (3.44)
3.47
decoder under test
DUT
decoder that is tested for conformance to this document by operating the hypothetical stream scheduler
to deliver a conforming bitstream (3.23) to the decoder and to the hypothetical reference decoder and
comparing the values and timing or order of the output of the two decoders
3.48
decoding unit
sub-set of a coded atlas access unit (3.35) consisting of one or more ACL NAL units in a coded atlas access
unit (3.35) and the associated non-ACL NAL units (3.2)
3.49
enhanced occupancy mode
EOM
patch coding mode where a patch (3.85) is associated with enhanced occupancy information
3.50
EOM coded points
coded representation of 3D points located at intermediate depth positions for which geometry (3.56)
values are stored as codewords in the occupancy frame (3.84) and their corresponding attributes values
are stored in additional patches, referred to as EOM patches (3.51), in the attribute frames (3.17)
3.51
EOM patch
patch (3.85) with patch mode (3.87) equal to I_EOM, P_EOM, or P_SKIP associated with EOM coded
points (3.50)
3.52
EOM patch type
patch type (3.88) indicating an EOM patch (3.51)
3.53
essential supplemental enhancement information
ESEI
SEI (3.117) that is deemed as essential by the decoding process and should not be ignored or discarded
6 © ISO/IEC 2021 – All rights reserved

3.54
essential supplemental enhancement information NAL unit
ESEI NAL unit
NAL unit (3.76) corresponding to an ESEI (3.53) and has nal_unit_type equal to NAL_PREFIX_ESEI or
NAL_SUFFIX_ESEI
3.55
flag
variable or single-bit syntax element that can take one of the two possible values: 0 and 1
3.56
geometry
set of Cartesian coordinates (3.30) associated with a volumetric frame (3.138)
3.57
geometry access unit
collection of geometry maps (3.59) and auxiliary geometry frames, if present, corresponding to the
same time instance
3.58
geometry frame
2D array created through the aggregation of the geometry (3.56) information associated with each
patch (3.85)
3.59
geometry map
geometry frame (3.58) containing geometry patch (3.85) information projected at a particular depth
3.60
global broken link access access unit
GBLA access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a GBLA coded atlas (3.61)
3.61
global broken link access coded atlas
GBLA coded atlas
IRAP coded atlas (3.73) frame for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_
GBLA_W_LP, NAL_GBLA_W_RADL, or NAL_GBLA_N_LP respectively
3.62
global clean random access access unit
GCRA access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a GCRA coded atlas (3.63)
3.63
global clean random access coded atlas
GCRA coded atlas
IRAP coded atlas (3.73) frame for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_GCRA
3.64
global instantaneous decoding refresh access unit
GIDR access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a GIDR coded atlas (3.65)
3.65
global instantaneous decoding refresh coded atlas access unit
GIDR-coded atlas
coded atlas (3.34) for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_GIDR_W_RADL,
NAL_GBLA_N_LP, or NAL_GCRA, or in the range of NAL_GBLA_W_LP to NAL_GBLA_N_LP, inclusive, and
specify a random access association between the current coded atlas and its corresponding coded video
frames at the same composition time
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3.66
global intra random access point coded atlas
GIRAP coded atlas
IRAP coded atlas (3.73) for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_GIDR_W_RADL,
NAL_GBLA_N_LP, or NAL_GCRA, or in the range of NAL_GBLA_W_LP to NAL_GBLA_N_LP, inclusive, and
specify a random access association between the current coded atlas and the corresponding coded
video frames at the same composition time
3.67
hypothetical reference decoder
HRD
hypothetical decoder model that specifies constraints on the variability of conforming atlas NAL unit
(3.76) streams or conforming coded atlas (3.34) sample streams that an encoding process can produce
3.68
hypothetical stream scheduler
HSS
hypothetical delivery mechanism used for checking the conformance of an atlas sub-bitstream (3.13) or
a decoder with regards to the timing and data flow of the input of an atlas sub-bitstream (3.13) into the
hypothetical reference decoder (3.67)
3.69
instantaneous decoding refresh coded atlas access unit
IDR coded atlas access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is an IDR coded atlas (3.70)
3.70
instantaneous decoding refresh coded atlas
IDR coded atlas
IRAP coded atlas (3.73) for which each ACL NAL unit (3.6) has nal_unit_type equal to NAL_IDR_W_RADL,
or NAL_IDR_N_LP, NAL_GIDR_W_RADL, or NAL_GIDR_N_LP
Note 1 to entry: An IDR coded atlas does not refer to any atlases other than itself for inter prediction in its
decoding process, and may be the first atlas in the bitstream in decoding order, or may appear later in the
bitstream. Each IDR coded atlas is the first atlas of a CAS in decoding order. When an IDR coded atlas for which
each ACL NAL unit has nal_unit_type equal to NAL_IDR_W_RADL or NAL_GIDR_W_RADL, it may have associated
RADL coded atlases. When an IDR coded atlas for which each ACL NAL unit has nal_unit_type equal to NAL_
IDR_N_LP or NAL_GIDR_N_LP, it does not have any associated leading coded atlases. An IDR coded atlas does not
have associated RASL coded atlases.
3.71
inter atlas tile
atlas tile that can be decoded using both intra or inter prediction methods
3.72
intra atlas tile
atlas tile that is decoded using only intra prediction methods
3.73
intra random access point coded atlas
IRAP coded atlas
IRAP coded atlas frame
coded atlas (3.34) for which each ACL NAL unit (3.6) has nal_unit_type in the range of NAL_BLA_W_LP to
NAL_RSV_IRAP_ACL_29, inclusive
Note 1 to entry: An IRAP coded atlas does not refer to any coded atlases other than itself for prediction in its
decoding process, and may be a BLA coded atlas, a CRA coded atlas, or an IDR coded atlas. Provided the necessary
parameter sets are available when they need to be activated, the IRAP coded atlas and all subsequent non-RASL
coded atlas in decoding order can be correctly decoded without performing the decoding process of any coded
atlases that precede the IRAP coded atlas in decoding order.
8 © ISO/IEC 2021 – All rights reserved

3.74
intra random access point coded atlas access unit
IRAP coded atlas access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a IRAP coded atlas (3.73)
3.75
multi-component collection of V3C sub-bitstreams
V3C sub-bitstreams (3.133) of multiple V3C components (3.129) that, when decoded, enable the
reconstruction of volumetric content
3.76
network abstraction layer unit
NAL unit
syntax structure containing an indication of the type of data to follow and bytes (3.24) containing that
data in the form of an RBSP (3.100)
3.77
network abstraction layer unit stream
NAL unit stream
sequence of NAL units (3.76)
3.78
non-ACL NAL unit
NAL unit (3.76) that is not an ACL NAL unit (3.6).
3.79
non-auxiliary video component
regular video component
video component (3.125) indicated as being of non-auxiliary type through an appropriate flag in the
VPS (3.134)
3.80
non-auxiliary video sub-bitstream
regular video sub-bitstream
video sub-bitstream (3.127) indicated as being of non-auxiliary type through an appropriate flag in the
VPS (3.134)
3.81
non-essential supplemental enhancement information
NSEI
SEI (3.117) that is deemed as non-essential by the decoding process and may be ignored or discarded
without any adverse effects
3.82
non-essential supplemental enhancement information NAL unit
NSEI NAL unit
NAL unit (3.76) corresponding to a NSEI (3.81) and has nal_unit_type equal to NAL_PREFIX_NSEI or
NAL_SUFFIX_NSEI
3.83
occupancy
values that indicate whether atlas samples (3.10) correspond to associated samples in 3D space
3.84
occupancy frame
collection of occupancy (3.83) values that constitute a 2D array and represents the entire occupancy
(3.83) information of a single atlas frame (3.8)
3.85
patch
rectangular region within an atlas (3.4) associated with volumetric information
© ISO/IEC 2021 – All rights reserved 9

3.86
patch data
data in an atlas (3.4) associated with a patch (3.85) that enables the conversion of 2D projected data
back to 3D space
3.87
patch mode
syntax element (3.119) in the atlas bitstream (3.5) that indicates how a patch (3.85) is defined and
associated with other V3C components (3.129) and provides information of how to reconstruct such V3C
components (3.129)
3.88
patch type
classification of patch modes (3.87) based on how the characteristics of a patch (3.85) are signalled and
interpreted
3.89
prefix ESEI NAL unit
essential SEI NAL unit (3.54) that has nal_unit_type equal to NAL_PREFIX_ESEI
3.90
prefix NSEI NAL unit
non-essential SEI NAL unit (3.82) that has nal_unit_type equal to NAL_PREFIX_NSEI
3.91
prefix SEI message
SEI (3.117) message that is contained in a prefix NSEI NAL unit (3.90) or prefix ESEI NAL unit (3.89)
3.92
prefix SEI NAL unit
SEI NAL unit (3.118) that has nal_unit_type equal to NAL_PREFIX_NSEI or NAL_PREFIX_ESEI
3.93
projected patch
patch (3.85) with patch mode (3.87) equal to I_INTRA, P_INTRA, P_INTER, P_MERGE, or P_SKIP that is
associated with projected information onto a 2D image
3.94
projected patch type
patch type (3.88) indicating a projected patch (3.93)
3.95
random access
the act of starting the decoding process for a bitstream (3.23) at a point other than the beginning of
the stream
3.96
random access decodable leading access unit
RADL access unit
access unit in which the coded atlas (3.34) with nal_layer_id equal to 0 is a RADL coded atlas (3.97)
3.97
ran
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