1、PD ISO/IEC TS 20071-25:2017 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 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/IEC
2、 TS 20071-25:2017 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO/IEC TS 20071-25:2017. The UK participation in its preparation was entrusted to Technical Committee ICT/-/6, Accessibility. A list of organizations represented on this committee can be obtained
3、on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 94128 3 ICS 35.240.20 Compliance wit
4、h a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017. Amendments/corrigenda issued since publication Date T e x t a f f e c t e dPD ISO/IEC TS 20071-25:2017 Informat
5、ion 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 linformation Accessibilit du composant interface utilisateur Partie 25: Lignes directrices sur la prsentation au
6、dio de texte dans des vidos, y compris les lgendes, sous-titres et autres textes lcran ISO/IEC TS 20071-25 First edition 2017-02 Reference number ISO/IEC TS 20071-25:2017(E) TECHNICAL SPECIFICATION ISO/IEC 2017 PD ISO/IEC TS 20071-25:2017ii ISO/IEC 2017 All rights reserved COPYRIGHT PROTECTED DOCUME
7、NT 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 writt
8、en permission. Permission can be requested from either ISO at the address below or ISOs 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 copyrightiso.org www.iso.org ISO/IEC TS
9、 20071-25:2017(E)PD ISO/IEC TS 20071-25:2017ISO/IEC TS 20071-25:2017(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms 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 con
10、siderations . 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 vi
11、deos 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
12、 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
13、.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
14、 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 Contents PagePD ISO/IEC TS 20071-25:2017ISO/
15、IEC TS 20071-25:2017(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
16、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
17、 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 parti
18、cular 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 o
19、f 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
20、 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 wel
21、l as information about ISOs 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
22、of all parts in the ISO/IEC/TS 20071 series can be found in the ISO website.iv ISO/IEC 2017 All rights reservedPD ISO/IEC TS 20071-25:2017ISO/IEC TS 20071-25:2017(E) Introduction Videos are omnipresent in our digital society and are used to inform, educate and entertain audiences. Videos often conta
23、in 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 pa
24、rt 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
25、 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
26、 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 a
27、ccess 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
28、 users are given the choice to select those best suited to their needs. ISO/IEC 2017 All rights reserved vPD ISO/IEC TS 20071-25:2017PD ISO/IEC TS 20071-25:2017Information technology User interface component accessibility Part 25: Guidance on the audio presentation of text in videos, including capti
29、ons, 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
30、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 languag
31、e 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
32、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 delive
33、r 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 do
34、es 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
35、 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. 2 Normative references There are no normative references in this document. 3 T erms a nd definiti ons For t
36、he purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .i
37、so .org/ obp TECHNICAL SPECIFICATION ISO/IEC TS 20071-25:2017(E) ISO/IEC 2017 All rights reserved 1PD ISO/IEC TS 20071-25:2017ISO/IEC TS 20071-25:2017(E) 3.1 General terms 3.1.1 video combination of audio and visual content presented together in a synchronized manner via ICT Note 1 to entry: While t
38、he visual content is often presented using a screen, it might also be presented via other technologies, e.g. a projected hologram. 3.1.2 programme complete unit of a recorded or live video 3.1.3 programme category classification of programmes Note 1 to entry: Programme categories are not necessarily
39、 mutually exclusive. EXAMPLE Programme categories include documentary, news and information, and drama. 3.2 A udio-specific t erms 3.2.1 spoken captions/subtitles audio captions/subtitles captions/subtitles that are voiced over the audiovisual content Note 1 to entry: In this document, the term “spo
40、ken captions/subtitles” will be used. 3.2.2 spoken on-screen text text, other than captions/subtitles, that is voiced over the audiovisual content 3.2.3 audio description descriptive audio audiovisual content described in an audio modality Note 1 to entry: Audio description can also be used to descr
41、ibe locations, directions, and objects. Note 2 to entry: Audio description can be used to describe sound not easily identified or coming from an unknown source or location. 3.2.4 narrator person(s) and/or technology which voices the alternative audio information Note 1 to entry: Alternative audio in
42、formation includes audio description and/or spoken captions/subtitles and/or spoken on-screen text. Note 2 to entry: In audio description, narrators are also referred to as describers or audio describers. 3.3 Language of presentation terms 3.3.1 original language language in which audiovisual conten
43、t is produced2 ISO/IEC 2017 All rights reservedPD ISO/IEC TS 20071-25:2017ISO/IEC TS 20071-25:2017(E) 3.3.2 dubbing secondary audio version of a video produced in a language other than the original language of the video and timed to match the voicing of the original actors Note 1 to entry: The secon
44、dary audio version is lip-synchronized and replaces the original dialogue, which cannot be heard. 3.3.3 voice-over secondary audio version of a video produced in a language other than the original language of the video which overlaps with the voicing of the original actors Note 1 to entry: The secon
45、dary audio version is not lip-synchronized and does not replace the original dialogue, which can still be heard. 3.3.4 captions/subtitles transcription or translation of audio content visually presented together with the content Note 1 to entry: Transcriptions or translations include speech and/or n
46、on-speech information. Note 2 to entry: Transcriptions or translations are often suitable for use as an alternative or a complement to the audio content. 3.4 Production terms 3.4.1 pre-mixed production process that involves delivering alternative audio information together with the audio stream of t
47、he video as one single audio track Note 1 to entry: Although pre-mixed is used in the definition to refer to the audio mix, it can also refer to a production process in which the original audio (including both the soundtrack and the dialogues), the alternative audio information in the video and the
48、original visual content are delivered together. Note 2 to entry: Pre-mixed productions are also referred to as broadcast-mixed productions. 3.4.2 receiver-mixed production process that involves delivering alternative audio information separately from the audio stream of the video and having them mix
49、ed in a device controlled by the user Note 1 to entry: Alternative audio information can be delivered to the user or be downloaded or streamed from the Internet as separate services or as services mixed in different combinations. 4 Framework and process considerations 4.1 General 4.1.1 Alternate names for the audio presentation of text in videos Terms used in this document vary according to country, language, region, video content and type of text in videos. They include audio subtitles, spoke
