ISO/IEC 21122-3:2022

INTERNATIONAL ISO/IEC
STANDARD 21122-3
Second edition
2022-03
Information technology — JPEG XS
low-latency lightweight image coding
system —
Part 3:
Transport and container formats
Reference number
© ISO/IEC 2022
© ISO/IEC 2022
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© ISO/IEC 2022 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.3
4.1 Symbols . 3
4.2 Abbreviated terms . 3
4.3 Naming conventions for numerical values . 3
5 Conformance . 4
6 Colour specification .4
7 Organization of the document .4
Annex A (normative) Use of JPEG XS codestreams in still image file format - JXS .5
Annex B (normative) Use of JPEG XS codestreams in the ISOBMFF - Motion JPEG XS .33
Annex C (normative) Use of JPEG XS codestreams in the HEIF image file format.37
Annex D (normative) Use of JPEG XS codestreams outside of file formats . 44
Bibliography .46
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© ISO/IEC 2022 – 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
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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 or
www.iec.ch/members_experts/refdocs).
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 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. In the IEC, see www.iec.ch/understanding-standards.
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.
This second edition cancels and replaces the first edition (ISO/IEC 21122-3:2019), which has been
technically revised.
The main changes are as follows:
— corrigenda;
— signalling for support of 4:2:0 images.
A list of all parts in the ISO/IEC 21122 series can be found on the ISO and IEC websites.
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 and
www.iec.ch/national-committees.
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© ISO/IEC 2022 – All rights reserved

Introduction
This document is part of a series of standards for a low-latency lightweight image coding system,
denoted JPEG XS.
In many use cases during production or transmission of a movie, limiting the latency and the
recompression loss is a more important aspect than the compression efficiency. The JPEG XS coding
system offers compression and recompression of image sequences with very moderate computational
resources while remaining robust under multiple compression and decompression cycles and mixing
of content sources, e.g. embedding of subtitles, overlays or logos. Typical target compression ratios
ensuring visually lossless quality are in the range of 2:1 to 10:1, depending on the nature of the source
material. The end-to-end latency can be confined to a fraction of a frame, typically between a small
number of lines down to below a single line.
This document specifies transport and container formats for JPEG XS codestreams. It also defines
metadata that enriches transport protocols for transmission of image sequences, in order to facilitate
transport, editing and presentation.
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© ISO/IEC 2022 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 21122-3:2022(E)
Information technology — JPEG XS low-latency lightweight
image coding system —
Part 3:
Transport and container formats
1 Scope
This document defines transport and container formats for JPEG XS codestreams as specified in
ISO/IEC 21122-1. It defines file formats for working with still image and motion image sequence files
on computer platforms and gives guidance on how to embed the codestream in transport streams,
allowing internet-based communication.
This document uses already existing specifications for file formats and extends them for the embedding
of JPEG XS codestreams.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes 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.
ISO 15076-1, Image technology colour management — Architecture, profile format and data structure —
Part 1: Based on ICC.1: 2010
ISO/IEC 646, Information technology — ISO 7-bit coded character set for information interchange
ISO/IEC 10646, Information technology — Universal coded character set (UCS)
ISO/IEC 11578, Information technology — Open Systems Interconnection — Remote Procedure Call (RPC)
ISO/IEC 14496-12, Coding of audio-visual objects — Part 12: ISO base media file format
ISO/IEC 21122-1, JPEG XS low-latency lightweight image coding system — Part 1: Core coding system
ISO/IEC 21122-2, JPEG XS low-latency lightweight image coding system — Part 2: Profiles and buffer
models
ISO/IEC 23008-12:2017, Information technology — High efficiency coding and media delivery in
heterogeneous environments — Part 12: Image File Format
ISO/CIE 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers
Rec. ITU-T H.273 | ISO/IEC 23091-2, Coding-independent code points — Part 2: Video
ANSI/CTA 861-G:2016, A DTV Profile for Uncompressed High Speed Digital Interfaces
W3C Recommendation, Extensible Markup Language (XML) 1.0 (Fifth Edition), 26 Nov. 2008 (https://
www .w3 .org/ TR/ REC -xml/ )
3 Terms and definitions
For the purposes of this document the terms and definitions given in ISO/IEC 14496-12, ISO/IEC 21122-1,
ISO/IEC 21122-2, ISO/IEC 23008-12 and the following apply.
© ISO/IEC 2022 – All rights reserved

ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
aux
auxiliary component channel typically used as opacity channel or alpha mask
3.2
big-endian
byte ordering from the most significant to the least significant byte of multi-byte value representations
3.3
box
structured collection of data describing the image or the image decoding process
3.4
box content
data wrapped within the box (3.3) structure
3.5
box type
kind of information stored with the box (3.3)
3.6
byte
group of 8 bits
3.7
coding-independent code point
code point based on enumerated values for the definition of the colourspaces
Note 1 to entry: Code points defined in Rec. ITU-T H.273 | ISO/IEC 23091-2.
3.8
high efficiency image file format
image file format which can embed still images and motion sequences (3.11)
Note 1 to entry: Based on ISO/IEC 23008-12.
3.9
image collection
unordered set of images without an implied or signalled presentation order or presentation time stamps
3.10
JXS
still image file format with JPEG XS compressed images
3.11
motion sequence
movie
timed sequence (3.15) of images
3.12
sample
single element in the two-dimensional image array which comprises a component
Note 1 to entry: This definition is used in Annex A.
[SOURCE: ISO/IEC 21122-1:2022, 3.1.45 modified – the domain and Note 1 to entry have been added.]
© ISO/IEC 2022 – All rights reserved

3.13
sample
all the data associated with a single time
Note 1 to entry: This definition is used in Annexes B and C as data associated with one coded image in a sequence.
3.14
superbox
box (3.3) that carries other boxes as payload data
3.15
timed sequence
linearly ordered sequence of media entities such as images where each entity is presented at a well
defined time stamp
4 Symbols and abbreviated terms
4.1 Symbols
N number of components in an image as defined in ISO/IEC 21122-1
c
Plev level a particular codestream conforms to as defined in ISO/IEC 21122-2
Ppih profile a particular codestream conforms to as defined in ISO/IEC 21122-2
Picture()
JPEG XS codestream as defined in ISO/IEC 21122-1
Codestream_Header()
codestream header preceding the image data in the codestream as defined
in A.5.5
Codestream_Body()
coded image data in the codestream without Codestream_Header() as
defined in A.5.5
4.2 Abbreviated terms
For the purposes of this document the abbreviated terms given in ISO/IEC 14496-12, ISO/IEC 21122-1,
ISO/IEC 21122-2, ISO/IEC 23008-12 and the following apply.
CICP coding-independent code points
CIE Commision Internationale de l’Eclairage
HEIF high efficiency image file format
ISOBMFF iso base media file format
LSB least significant bit
MSB most significant bit
UTF-8 8-bit Unicode transformation format as defined in ISO/IEC 10646
4.3 Naming conventions for numerical values
Integer numbers are expressed as bit patterns, hexadecimal values, or decimal numbers. Bit patterns
and hexadecimal values have both a numerical value and an associated particular length in bits.
Hexadecimal notation, indicated by prefixing the hexadecimal number by "0x", may be used instead
of binary notation to denote a bit pattern having a length that is an integer multiple of 4. For example,
© ISO/IEC 2022 – All rights reserved

0x41 represents an eight-bit pattern having only its second most significant bit and its least significant
bit equal to 1. Numerical values that are specified under a "Code" heading in tables that are referred to
as "code tables" are bit pattern values (specified as a string of digits equal to 0 or 1 in which the left-
most bit is considered the most-significant bit). Other numerical va
...