ISO/IEC TS 20071-25:2017
(Main)Information technology — User interface component accessibility — Part 25: Guidance on the audio presentation of text in videos, including captions, subtitles and other on-screen text
Information technology — User interface component accessibility — Part 25: Guidance on the audio presentation of text in videos, including captions, subtitles and other on-screen text
ISO/IEC TS 20071-25:2017 provides recommendations on the audio presentation of captions/subtitles and other on-screen text for use in all type of videos regardless of the language and technology being used to transmit and present the recorded or live video. ISO/IEC TS 20071-25:2017 applies to making captions/subtitles and other on-screen text accessible to users with various needs, including but not limited to people with learning and reading disabilities, people with cognitive disabilities, people who are blind or have low vision, older people, and non-native language speakers. It does not apply to captions/subtitles or other on-screen text whose content is already provided in the soundtrack in a language and a way users can access. ISO/IEC TS 20071-25:2017 provides guidance on spoken captions/subtitles as a stand-alone access service but it also provides guidance on how to integrate spoken captions/subtitles, other spoken on-screen text and audio description, if needed, in different types of videos. NOTE 1 Extensive guidance on audio description is provided in ISO/IEC/TS 20071‑21. ISO/IEC TS 20071-25:2017 does not consider the devices or transmission mechanisms used to deliver and play the content or the audio presentation of text in videos. These devices include, but are not limited to televisions, computers, wireless devices, projection equipment, DVD and home cinema equipment, cinema equipment and other forms of user interfaces technology. Therefore, this document does not consider transcoding files for the various video and audio outputs. NOTE 2 Technical matters of transmission and distribution are covered by other documents (e.g. MPEG standards and other technical standards such as IEC 62731:2013). ISO/IEC TS 20071-25:2017 acknowledges the various needs and preferences of users, as well as the different approaches to the audio presentation of text in videos. It applies to audio presentations intended to be heard simultaneously along with the original video.
Technologies de l'information — Accessibilité du composant interface utilisateur — Partie 25: Lignes directrices sur la présentation audio de texte dans des vidéos, y compris les légendes, sous-titres et autres textes à l'écran
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TECHNICAL ISO/IEC TS
SPECIFICATION 20071-25
First edition
2017-02
Information technology — User
interface component accessibility —
Part 25:
Guidance on the audio presentation
of text in videos, including captions,
subtitles and other on-screen text
Technologies de l’information — Accessibilité du composant interface
utilisateur —
Partie 25: Lignes directrices sur la présentation audio de texte dans
des vidéos, y compris les légendes, sous-titres et autres textes à l’écran
Reference number
©
ISO/IEC 2017
© ISO/IEC 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO/IEC 2017 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 2
3.2 Audio-specific terms . 2
3.3 Language of presentation terms . 2
3.4 Production terms . 3
4 Framework and process considerations . 3
4.1 General . 3
4.1.1 Alternate names for the audio presentation of text in videos . 3
4.1.2 Motivation for the audio presentation of text in videos. 4
4.2 Types of text in videos . 4
4.2.1 Captions/subtitles . 4
4.2.2 Other on-screen text . 5
4.3 Types of audio presentations of text in videos . 5
4.3.1 Live and recorded spoken captions/subtitles and spoken on-screen text . 5
4.3.2 Pre-mixed and receiver-mixed productions. 6
4.4 Creating and delivering audio presentations of text in videos . 6
4.4.1 Narrator preparation . 6
4.4.2 Volume . 6
4.4.3 Audio quality . 7
4.4.4 Inclusion of users in creating the audio presentation of text in videos . 7
4.4.5 Inclusion of users in evaluating the audio presentation of text in videos . 7
4.5 Synchronization . 7
4.6 Text-files . 7
5 Guidance on the audio presentation of text in videos . 8
5.1 General considerations . 8
5.1.1 Different strategies . 8
5.1.2 User considerations. 8
5.1.3 Availability across technologies . 8
5.1.4 Consistency within a video and programme series . 9
5.2 Developing the audio presentation of text in videos . 9
5.2.1 Clarity in the audio presentation of text in videos . 9
5.2.2 Reading/delivering the audio presentation of text in videos . 9
5.3 Levels of importance . 9
5.4 Guidance on identifying the audio presentation of text in videos . 9
5.5 Guidance on identifying characters .10
5.6 Guidance on text and speech adjustments .10
Bibliography .12
© ISO/IEC 2017 – 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. 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 ISO documents 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 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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by ISO/JTC1, Information technology, Subcommittee SC 35, User interfaces.
A list of all parts in the ISO/IEC/TS 20071 series can be found in the ISO website.
iv © ISO/IEC 2017 – All rights reserved
Introduction
Videos are omnipresent in our digital society and are used to inform, educate and entertain audiences.
Videos often contain text, which cannot be easily accessed by a wide section of the audience. This text
includes captions/subtitles and other on-screen text that is part of the visual content.
Captions/subtitles provide text alternatives to audio elements. Other on-screen text may have various
functions. It can be part of the story, as a message written on a piece of paper by one of the characters. It
can also provide additional information, such as graphs, emergency alerts or superimposed titles.
Persons who, for different reasons, cannot access on-screen text will benefit from an audio presentation.
This oral rendering is often part of audio description (see ISO/IEC/TS 20071-21), an access service
providing a description of audiovisual content auditorily, including captions/subtitles and other on-
screen text if present. However, some users may only require captions/subtitles and other on-screen
text to be made accessible because they already have access to other visual content such as the images.
This document provides guidance for video producers, distributors and exhibitors on the audio
presentation of captions/subtitles and other on-screen text. It acknowledges the relationship with
existing access services such as audio description. While considering current implementations, as well
as future possibilities suggested by research, and bearing in mind possible trade-offs between quantity
and quality, this document positions itself for situations in which various access services coexist and
users are given the choice to select those best suited to their needs.
© ISO/IEC 2017 – All rights reserved v
TECHNICAL SPECIFICATION ISO/IEC TS 20071-25:2017(E)
Information technology — User interface component
accessibility —
Part 25:
Guidance on the audio presentation of text in videos,
including captions, subtitles and other on-screen text
1 Scope
This document provides recommendations on the audio presentation of captions/subtitles and other
on-screen text for use in all type of videos regardless of the language and technology being used to
transmit and present the recorded or live video.
This document applies to making captions/subtitles and other on-screen text accessible to users with
various needs, including but not limited to people with learning and reading disabilities, people with
cognitive disabilities, people who are blind or have low vision, older people, and non-native language
speakers. It does not apply to captions/subtitles or other on-screen text whose content is already
provided in the soundtrack in a language and a way users can access.
This document provides guidance on spoken captions/subtitles as a stand-alone access service but it
also provides guidance on how to integrate spoken captions/subtitles, other spoken on-screen text and
audio description, if needed, in different types of videos.
NOTE 1 Extensive guidance on audio description is provided in ISO/IEC/TS 20071-21.
This document does not consider the devices or transmission mechanisms used to deliver and play
the content or the audio presentation of text in videos. These devices include, but are not limited to
televisions, computers, wireless devices, projection equipment, DVD and home cinema equipment,
cinema equipment and other forms of user interfaces technology. Therefore, this document does not
consider transcoding files for the various video and audio outputs.
NOTE 2 Technical matters of transmission and distribution are covered by other documents (e.g. MPEG
standards and other technical standards such as IEC 62731:2013).
This document acknowledges the various needs and preferences of users, as well as the different
approaches to the audio presentation of text in videos.
It applies to audio presentations intended to be heard
...
TECHNICAL ISO/IEC TS
SPECIFICATION 20071-25
First edition
2017-02
Information technology — User
interface component accessibility —
Part 25:
Guidance on the audio presentation
of text in videos, including captions,
subtitles and other on-screen text
Technologies de l’information — Accessibilité du composant interface
utilisateur —
Partie 25: Lignes directrices sur la présentation audio de texte dans
des vidéos, y compris les légendes, sous-titres et autres textes à l’écran
Reference number
©
ISO/IEC 2017
© ISO/IEC 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO/IEC 2017 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 2
3.2 Audio-specific terms . 2
3.3 Language of presentation terms . 2
3.4 Production terms . 3
4 Framework and process considerations . 3
4.1 General . 3
4.1.1 Alternate names for the audio presentation of text in videos . 3
4.1.2 Motivation for the audio presentation of text in videos. 4
4.2 Types of text in videos . 4
4.2.1 Captions/subtitles . 4
4.2.2 Other on-screen text . 5
4.3 Types of audio presentations of text in videos . 5
4.3.1 Live and recorded spoken captions/subtitles and spoken on-screen text . 5
4.3.2 Pre-mixed and receiver-mixed productions. 6
4.4 Creating and delivering audio presentations of text in videos . 6
4.4.1 Narrator preparation . 6
4.4.2 Volume . 6
4.4.3 Audio quality . 7
4.4.4 Inclusion of users in creating the audio presentation of text in videos . 7
4.4.5 Inclusion of users in evaluating the audio presentation of text in videos . 7
4.5 Synchronization . 7
4.6 Text-files . 7
5 Guidance on the audio presentation of text in videos . 8
5.1 General considerations . 8
5.1.1 Different strategies . 8
5.1.2 User considerations. 8
5.1.3 Availability across technologies . 8
5.1.4 Consistency within a video and programme series . 9
5.2 Developing the audio presentation of text in videos . 9
5.2.1 Clarity in the audio presentation of text in videos . 9
5.2.2 Reading/delivering the audio presentation of text in videos . 9
5.3 Levels of importance . 9
5.4 Guidance on identifying the audio presentation of text in videos . 9
5.5 Guidance on identifying characters .10
5.6 Guidance on text and speech adjustments .10
Bibliography .12
© ISO/IEC 2017 – 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. 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 ISO documents 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 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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by ISO/JTC1, Information technology, Subcommittee SC 35, User interfaces.
A list of all parts in the ISO/IEC/TS 20071 series can be found in the ISO website.
iv © ISO/IEC 2017 – All rights reserved
Introduction
Videos are omnipresent in our digital society and are used to inform, educate and entertain audiences.
Videos often contain text, which cannot be easily accessed by a wide section of the audience. This text
includes captions/subtitles and other on-screen text that is part of the visual content.
Captions/subtitles provide text alternatives to audio elements. Other on-screen text may have various
functions. It can be part of the story, as a message written on a piece of paper by one of the characters. It
can also provide additional information, such as graphs, emergency alerts or superimposed titles.
Persons who, for different reasons, cannot access on-screen text will benefit from an audio presentation.
This oral rendering is often part of audio description (see ISO/IEC/TS 20071-21), an access service
providing a description of audiovisual content auditorily, including captions/subtitles and other on-
screen text if present. However, some users may only require captions/subtitles and other on-screen
text to be made accessible because they already have access to other visual content such as the images.
This document provides guidance for video producers, distributors and exhibitors on the audio
presentation of captions/subtitles and other on-screen text. It acknowledges the relationship with
existing access services such as audio description. While considering current implementations, as well
as future possibilities suggested by research, and bearing in mind possible trade-offs between quantity
and quality, this document positions itself for situations in which various access services coexist and
users are given the choice to select those best suited to their needs.
© ISO/IEC 2017 – All rights reserved v
TECHNICAL SPECIFICATION ISO/IEC TS 20071-25:2017(E)
Information technology — User interface component
accessibility —
Part 25:
Guidance on the audio presentation of text in videos,
including captions, subtitles and other on-screen text
1 Scope
This document provides recommendations on the audio presentation of captions/subtitles and other
on-screen text for use in all type of videos regardless of the language and technology being used to
transmit and present the recorded or live video.
This document applies to making captions/subtitles and other on-screen text accessible to users with
various needs, including but not limited to people with learning and reading disabilities, people with
cognitive disabilities, people who are blind or have low vision, older people, and non-native language
speakers. It does not apply to captions/subtitles or other on-screen text whose content is already
provided in the soundtrack in a language and a way users can access.
This document provides guidance on spoken captions/subtitles as a stand-alone access service but it
also provides guidance on how to integrate spoken captions/subtitles, other spoken on-screen text and
audio description, if needed, in different types of videos.
NOTE 1 Extensive guidance on audio description is provided in ISO/IEC/TS 20071-21.
This document does not consider the devices or transmission mechanisms used to deliver and play
the content or the audio presentation of text in videos. These devices include, but are not limited to
televisions, computers, wireless devices, projection equipment, DVD and home cinema equipment,
cinema equipment and other forms of user interfaces technology. Therefore, this document does not
consider transcoding files for the various video and audio outputs.
NOTE 2 Technical matters of transmission and distribution are covered by other documents (e.g. MPEG
standards and other technical standards such as IEC 62731:2013).
This document acknowledges the various needs and preferences of users, as well as the different
approaches to the audio presentation of text in videos.
It applies to audio presentations intended to be heard
...
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