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

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Publication Date
13-Oct-2020
Current Stage
9599 - Withdrawal of International Standard
Completion Date
27-Sep-2022
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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 21122-5:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 21122-5:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© 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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 21122-5:2020(E)
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
---------------------- Page: 3 ----------------------
ISO/IEC 21122-5:2020(E)
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
---------------------- Page: 4 ----------------------
ISO/IEC 21122-5:2020(E)
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.

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
---------------------- Page: 5 ----------------------
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
---------------------- Page: 6 ----------------------
ISO/IEC 21122-5:2020(E)
+ 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
---------------------- Page: 7 ----------------------
ISO/IEC 21122-5:2020(E)
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
...

DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 21122-5
ISO/IEC JTC 1/SC 29 Secretariat: JISC
Voting begins on: Voting terminates on:
2019-10-28 2020-01-20
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
ICS: 35.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/IEC DIS 21122-5:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO/IEC 2019
---------------------- Page: 1 ----------------------
ISO/IEC DIS 21122-5:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2019

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC DIS 21122-5:2019(E)
CONTENTS
Page

Foreword ................................................................................................................................................................. ii

1. Scope ............................................................................................................................................................ 1

2. Normative references ................................................................................................................................... 1

3. Definitions, abbreviations and symbols ....................................................................................................... 1

3.1. Definitions .................................................................................................................................................... 1

3.2. Abbreviations ............................................................................................................................................... 1

4. Conventions.................................................................................................................................................. 2

4.1. Operators ...................................................................................................................................................... 2

4.1.1. Arithmetic operators ..................................................................................................................................... 2

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 ............................................................................................................................................................... 4

A.1. Unpacking the software ................................................................................................................................ 4

A.2. Prerequisites for building the software ......................................................................................................... 4

A.2.1. Prerequisites for building the software under a POSIX compliant system ................................................... 4

A.2.2. Prerequisites for building the software under Windows ........................................................................... 4

A.3. Compiling the software ................................................................................................................................ 4

A.3.1. Compiling the software under a POSIX compliant operating system .......................................................... 4

A.3.2. Compiling the software under Windows .................................................................................................. 4

B.1. General ......................................................................................................................................................... 5

B.2. ppm format ................................................................................................................................................... 5

B.2.1. ppm capabilities ........................................................................................................................................... 5

B.2.2. Description of the ppm header ..................................................................................................................... 5

B.2.3. Description of the ppm body ........................................................................................................................ 5

B.3. yuv format description ................................................................................................................................. 5

ANNEX C ............................................................................................................................................................... 7

C.1. Introduction .................................................................................................................................................. 7

C.2. Running the sample software encoder .......................................................................................................... 7

C.3. Running the reference software decoder ...................................................................................................... 8

Bibliography ................................................................................................................................................. 9

© ISO 2019 - All rights reserved i
---------------------- Page: 3 ----------------------
ISO/IEC DIS 21122-5:2019(E)
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. In the field of information technology, ISO and IEC have established a joint technical committee,

ISO/IEC JTC 1.

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).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on 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 the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by 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.
ii © ISO 2019 - All rights reserved
---------------------- Page: 4 ----------------------
ISO/IEC DIS 21122-5:2019(E)
Introduction

This International Standard 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 JPEG XS standard.
© ISO 2019 - All rights reserved iii
---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/IEC DIS 21122-5:2019(E)
Information technology — JPEG XS low-latency lightweight
image coding system —
Part 5:
Reference software
1. Scope

The ISO/IEC 21122 standard, also known under the term JPEG XS, specifies a low-latency, lightweight image

compression system offering compression tools for high-speed, ultra-low online compression of images and image

sequences.

This document contains the reference software of JPEG XS. Its purpose is to act as a guideline for implementations and

as a reference for conformance testing. It has been successfully compiled and tested on Linux and Windows operating

systems at the time of writing.
2. Normative references

The following Recommendations and International Standards contain provisions which, through reference in this text,

constitute provisions of this document. At the time of publication, the editions indicated were valid. All

Recommendations and Standards are subject to revision, and parties to agreements based on this document are

encouraged to investigate the possibility of applying the most recent edition of the Standards listed below. Members of

IEC and ISO maintain registers of currently valid International Standards.

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. Definitions, abbreviations and symbols
3.1. Definitions

For the purposes of this Recommendation | International Standard, the terms, definitions and abbreviated terms given in

ISO/IEC 21122-1, ISO/IEC 21122-2, ISO/IEC 21122-4 and the following apply.
3.1.1.
reference software decoder
software decoder provided as an electronic attachment to this document.
3.1.2.
testing
process of evaluating conformance
3.2. Abbreviations
For the purposes of this document, the following abbreviations apply.
MSE Mean Square Error
PSNR Peak Signal to Noise Ratio
© ISO 2019 - All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/IEC DIS 21122-5:2019(E)
4. Conventions
4.1. Operators

NOTE – Many of the operators used in this document are similar to those used in the C programming language.

4.1.1. Arithmetic operators
+ 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 standard. Requirements established in ISO/IEC 21122-1 and ISO/IEC 21122-2

take precedence over the behaviour of the reference software.

The reference software is normative in the sense that the output its decoder generates is the normative output of the

decoding process specified by ISO/IEC 21122-1. ISO/IEC 21122-4 therefore defines conformance testing by means of

comparing the output of a candidate implementation by that of the reference software specified in this document. It is

also normative in the sense that it allows validation of the codestream syntax by attempting to decode a candidate

codestream with the reference software decoder. A candidate codestream that is not decodable by the reference software

decoder is not conforming to the syntax specified in ISO/IEC 21122-1.
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 (Conformance Testing). 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

2 © ISO 2019 - All rights reserved
---------------------- Page: 7 ----------------------
ISO/IEC DIS 21122-5:2019(E)

conformance to ISO/IEC 21122-1 and ISO/IEC 21122-2, such as for example testing the conformance to the buffer

models specified there.
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 implem
...

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