ISO/IEC 21122-1:2024/Amd 1:2026

Technologies de l'information — Système de codage d'images léger à faible latence JPEG XS — Partie 1: Système de codage de noyau — Amendement 1: Titre manque

General Information

• Status: Published
• Publication Date: 12-May-2026
• ICS: 35.040.30 - Coding of graphical and photographical information
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29/WG 1 - JPEG Coding of digital representations of images
• Current Stage: 6060 - International Standard published
• Start Date: 13-May-2026
• Due Date: 06-Jan-2027
• Completion Date: 13-May-2026

Relations

• Amends: ISO/IEC 21122-1:2024 - Information technology — JPEG XS low-latency lightweight image coding system — Part 1: Core coding system
• Effective Date: 16-Aug-2025

Overview

ISO/IEC 21122-1:2024/Amd 1:2026 is an international standard amendment published by ISO and IEC that updates the JPEG XS low-latency lightweight image coding system, specifically augmenting Part 1: Core coding system. This amendment introduces the concept of slice synchronous metadata, enabling the attachment of metadata segments that are synchronized with image slices during the encoding and decoding process.

JPEG XS is designed for applications demanding low latency and lightweight compression, such as live video broadcasting, professional media transport, and real-time image streaming. The introduction of slice synchronous metadata in this amendment adds new capabilities for embedding generic or vendor-specific information within the image codestream.

Key Topics

• JPEG XS Codestream Structure: The amendment further details the organization and syntax of the JPEG XS codestream, updating how markers are processed for capabilities, headers, and component information.
• Slice Synchronous Metadata Marker (SYM): This new marker allows metadata segments to be inserted immediately after each slice, providing additional information synchronized with the image data.
• Capabilities Extension: The cap[] array is expanded to indicate whether slice synchronous metadata is required, among other advanced feature flags.
• Metadata Flexibility: The SYM marker supports both standard and vendor-specific metadata types, increasing adaptability for diverse applications. Standard types include vendor identification and copyright statements.
• Backward Compatibility and Optional Use: The amendment is designed as an optional extension; conforming decoders can ignore this metadata if not supported.

Applications

ISO/IEC 21122-1:2024/Amd 1:2026 is highly relevant for industries and solutions where precise control, annotation, or vendor-specific signaling needs to be integrated with low-latency image transmission. Example use cases include:

• Live Broadcast and Production: Embedding synchronization data, time codes, or provenance metadata with individual slices can streamline workflows in live video production pipelines.
• Professional Media Transport: OTT platforms, studios, and broadcasters can use slice synchronous metadata to ensure frame-accurate tracking and automated content processing.
• Medical and Scientific Imaging: Facilitates insertion of real-time supplementary information (e.g., timestamps, sensor data, annotations) on a per-slice basis for high-precision analysis.
• Security and Surveillance: Enables immediate and secure binding of authentication or event metadata to image slices transmitted in surveillance or monitoring systems.
• Vendor-Specific Integrations: Manufacturers and solution providers can attach proprietary metadata, device IDs, or custom instructions directly into the codestream, enhancing system flexibility and interoperability.

Related Standards

For best practices and effective implementation, ISO/IEC 21122-1:2024/Amd 1:2026 should be considered within the context of these related standards:

• ISO/IEC 21122-1:2024: Core coding system for JPEG XS, specifying baseline encoder and decoder operation.
• ISO/IEC 21122-2: Profiles and levels for JPEG XS, providing further granularity and compliance management.
• ISO/IEC 21122 Series: Full suite covering system integration, transport, and advanced features for JPEG XS.
• ISO/IEC 10646: Unicode standard referenced for encoding string metadata in slice synchronous segments.

Practical Value

By defining slice synchronous metadata, this amendment to JPEG XS gives developers and system integrators a standard approach to embed per-slice information efficiently and reliably. Whether for intellectual property tracking, real-time analytics, or equipment integration, ISO/IEC 21122-1:2024/Amd 1:2026 enhances the flexibility, transparency, and interoperability of low-latency image transport and broadcasting workflows.

For more information or to purchase the standard, visit the ISO website and IEC website.

Standards Content (Sample)

International
Standard
ISO/IEC 21122-1
Third edition
Information technology — JPEG
2024-07
XS low-latency lightweight image
coding system —
AMENDMENT 1
2026-05
Part 1:
Core coding system
AMENDMENT 1: Slice synchronous
metadata
Reference number
ISO/IEC 21122-1:2024/Amd. 1:2026(en) © ISO/IEC 2026

ISO/IEC 21122-1:2024/Amd. 1:2026(en)
© ISO/IEC 2026
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© ISO/IEC 2026 – All rights reserved
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ISO/IEC 21122-1:2024/Amd. 1:2026(en)
Foreword
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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.
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© ISO/IEC 2026 – All rights reserved
iii
ISO/IEC 21122-1:2024/Amd. 1:2026(en)
Information technology — JPEG XS low-latency lightweight
image coding system —
Part 1:
Core coding system
AMENDMENT 1: Slice synchronous metadata

A.2.1, Table A.1
Replace Table A.1 with the following table:
Table A.1 — JPEG XS codestream syntax overview
Syntax Notes Defined in
Picture() {
Identifies this codestream as JPEG XS code-
SOC_marker()
Table A.3
stream
Identifies the capabilities a decoder needs to
capabilities_marker()
Table A.6
support to be able to decode the codestream
Defines the overall structure of the code-
picture_header()
Table A.7
stream
Defines the precision and sampling factors of
component_table()
Table A.15
all components in the image
Defines weight and gain factors that steer
weights_table() Table A.25
the decoding process.
Defines weights and gain factors for forcibly
intra_weights_table()
Table A.26
refreshed bands in TDC-enabled slices
Optional definition of non-linearities for
nonlinearity_marker()
Table A.16
component reconstruction
Optionally disable wavelet decomposition on
cwd_marker()
Table A.18
some components
Colour transformation specification for the
cts_marker()
Table A.19
star-tetrix transformation
Optional component registration, mandatory
crg_marker()
Table A.21
if the star-tetrix transformation is used
Optional indication of TDC modes and re-
tpc_marker()
fresh groups, mandatory if SLI markers are Table A.22
used.
extension_marker()
Zero or more extension makers Table A.23
Loop over all slices until all wavelet coef-
ficients of the image have been decoded,
for(t=0,p=0;!endofimage;t=t+1) {

where t is the slice index and p the precinct
index
© ISO/IEC 2026 – All rights reserved
ISO/IEC 21122-1:2024/Amd. 1:2026(en)
TTabablele A A.11 ((ccoonnttiinnueuedd))
Syntax Notes Defined in
Identifies the ordering of slices and identifies
slice_header()
Table A.27,
the TDC mode of the slice. The slice header
or
shall be either an SLH or SLI header, depend-
Table A.28
tdc_slice_header()
ing on the profile of the codestream.
Loops over all precincts in a slice, where t is
for(u=0;u the slice index, p is the precinct index and u
p
enumerates precincts within a slice
Determine the packets that are part of this
compute_packet_inclusion(p) Table B.4
precinct.
Defines prediction modes and the quantiza-
precinct_header(p)
Table C.1
tion of the precinct
for(s=0;s pc
packet_header(p,s) Defines flags and sizes of the packet Table C.4
Contains the entropy coded data of this
packet_body(p,s)
Table C.4
packet
}
End of loop over subpackets
Possible byte-aligned filler bytes at the end
of the precinct to reach the target bitrate.
fill()
A decoder shall ignore this data. Clause C.2 Clause C.2
specifies how to determine the number of
filler bytes.
}
End of loop over precincts within a slice
Zero or more slice syncronous metadata
sym_marker()
Table A.29
markers
} End of loop over slices
EOC_marker()
Identifi
...