ISO/IEC 21122-5:2020

Information technology - JPEG XS low-latency lightweight image coding system - Part 5: Reference software

This document contains the reference software of the ISO/IEC 21122 series. It acts as a guideline for implementation and as a reference for conformance testing.

Technologies de l'information — Système de codage d’images léger à faible latence JPEG XS — Partie 5: Logiciel de référence

General Information

• Status: Withdrawn
• Publication Date: 13-Oct-2020
• 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: 9599 - Withdrawal of International Standard
• Start Date: 27-Sep-2022
• Completion Date: 30-Oct-2025

Relations

• Revised: ISO/IEC 21122-5:2022 - Information technology - JPEG XS low-latency lightweight image coding system - Part 5: Reference software
• Effective Date: 26-Nov-2021

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 21122-5
First edition
2020-10
Information technology — JPEG XS
low-latency lightweight image coding
system —
Part 5:
Reference software
Technologies de l'information — Système de codage d’images léger à
faible latence JPEG XS —
Partie 5: Logiciel de référence
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 1
4 Conventions . 1
4.1 Operators . 1
4.2 Typesetting . 2
5 Reference software . 2
5.1 Purpose . 2
5.2 Examples of use . 2
5.3 Layout of this document . 3
6 Copyright, licensing and intellectual property . 3
Annex A (informative) Unpacking and compiling the reference software .4
Annex B (informative) File formats read and written by the reference software .6
Annex C (informative) Using the reference software . 9
Bibliography .12
© ISO/IEC 2020 – All rights reserved iii

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 https:// 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 21122 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.
iv © ISO/IEC 2020 – 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 provides the reference software of the ISO/IEC 21122 series. It has been successfully
1) TM1)
compiled and tested on Linux® and Windows operating systems at the time of writing.
TM
1) Linux® and Windows are examples of suitable products available commercially. This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO or IEC of these products.
© ISO/IEC 2020 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 21122-5:2020(E)
Information technology — JPEG XS low-latency lightweight
image coding system —
Part 5:
Reference software
1 Scope
This document contains the reference software of the ISO/IEC 21122 series. It acts as a guideline for
implementation and as a reference for conformance testing.
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/IEC 21122-1, Information technology — JPEG XS low-latency lightweight image coding system —
Part 1: Core coding system
ISO/IEC 21122-2, Information technology — JPEG XS low-latency lightweight image coding system —
Part 2: Profiles and buffer models
ISO/IEC 21122-4, Information technology — JPEG XS low-latency lightweight image coding system —
Part 4: Conformance testing
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 21122-1, ISO/IEC 21122-2,
ISO/IEC 21122-4 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/
3.2 Abbreviated terms
MSE mean square error
PSNR peak signal to noise ratio
4 Conventions
4.1 Operators
NOTE Many of the operators used in this document are similar to those used in the C programming language.
© ISO/IEC 2020 – All rights reserved 1

+ addition
− subtraction (as a binary operator) or negation (as a unary prefix operator)
× multiplication
/ division without truncation or rounding
4.2 Typesetting
Regular face fonts as this text describe informative text that provides instructions, comments or details
for the reader.
Monospaced text as this paragraph indicates program input or output as necessary to either
run the software, or as generated by the software on the console.
5 Reference software
5.1 Purpose
The purpose of this document is to provide the following.
— Provide a reference decoder software capable of decoding codestreams that conform to
ISO/IEC 21122-1, or to ISO/IEC 21122-1 and ISO/IEC 21122-2.
— Provide a sample encoder software capable of producing codestreams that conform to
ISO/IEC 21122-1 and ISO/IEC 21122-2.
The use of the reference software is not required for making an implementation of an encoder or
decoder in conformance to any of the parts of the ISO/IEC 21122 series. Requirements established in
ISO/IEC 21122-1 and ISO/IEC 21122-2 take precedence over the behaviour of the reference software.
The reference software decoder generates the output of the decoding process specified by
ISO/IEC 21122-1. It therefore allows conformance testing by means of comparing the output of a
candidate implementation by that of the reference software specified in this document. Conformance
testing is specified in ISO/IEC 21122-4. The reference software decoder can also be used to validate
the syntactic correctness of a codestream by attempting to decode a candidate codestream with the
reference software.
5.2 Examples of use
Some examples of use for the reference decoder software implementations are as follows:
— As an illustration of how to perform the decoding processes specified in ISO/IEC 21122-1.
— As the starting basis for the implementation of a decoder that conforms to ISO/IEC 21122-1.
— For testing the conformance of a decoder implementation to ISO/IEC 21122-1 with the procedures
specified in ISO/IEC 21122-4. Details on reference testing can be found in ISO/IEC 21122-4.
— For (non-exhaustive) testing of the conformance of a codestream (or file) to the constraints specified
in ISO/IEC 21122-1.
The lack of detection of any conformance violation by any reference software implementation should not
be considered as a definite proof that the codestream under testing conforms to all constraints required
for it be conforming to ISO/IEC 21122-1. In fact, ISO/IEC 21122-4 defines additional testing procedures
that can be used to test a codestream for conformance to ISO/IEC 21122-1 and ISO/IEC 21122-2, such as
for example testing the conformance to the buffer models specified there.
2 © ISO/IEC 2020 – All rights reserved

Some examples of use for a sample encoder software are as follows:
— As an illustration of how to implement an encoding process that produces codestreams that are
conforming to ISO/IEC 21122-1 and ISO/IEC 21122-2.
— As starting point for an implementation of an encoder that conforms to ISO/IEC 21122-1 and
ISO/IEC 21122-2.
— As a means of generating codestreams conforming to ISO/IEC 21122-1 and ISO/IEC 21122-2 for
testing purposes.
— As a means of demonstrating and evaluating examples of the quality that can be achieved by an
encoding process that conforms to ISO/IEC 21122-1 and ISO/IEC 21122-2.
However, no guarantee of the quality that will be achieved by an encoder is provided by its conformance
to ISO/IEC 21122-1 as the conformance is only defined in terms of specific constraints imposed on the
syntax of the generated codestream. In particular, while sample encoder software implementations
may suffice to provide some illustrative examples of which quality can be achieved within the
ISO/IEC 21122 series, they provide neither an assurance of minimum guaranteed image encoding
quality nor maximum achievable image encoding quality.
Similarly, the computation resource characteristics in terms of program or data memory usage,
execution speed, etc. of sample software encoder or decoder implementations should not be construed
as a representative of the typical, minimal or maximal computational resource characteristics to be
exhibited by implementations of ISO/IEC 21122-1.
5.3 Layout of this document
Annex A describes unpacking, configuration and compiling the reference software. Annex B describes
the file formats in which the sample encoder accepts images and into which the reference decoder
reconstructs images. Annex C describes its use as encoder or decoder. In addition to the main text, the
reference software is available at https:// standards .iso .org/ iso -iec/ 21122/ -5/ ed -1/ en.
6 Copyright, licensing an
...