SIST EN 62731:2018

SLOVENSKI STANDARD
SIST EN 62731:2018
01-november-2018
1DGRPHãþD
SIST EN 62731:2013
Pretvorba besedila v govor (govorna sinteza) za televizijo - Splošne zahteve
Text to speech for television - General requirements
Text-zu-Sprache für Fernsehen - Allgemeine Anforderungen
Synthèse vocale pour télévision - Exigences générales
Ta slovenski standard je istoveten z: EN IEC 62731:2018
ICS:
33.160.25 Televizijski sprejemniki Television receivers
SIST EN 62731:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Synthèse vocale pour télévision - Exigences générales Text-zu-Sprache für Fernsehen - Allgemeine

This European Standard was approved by CENELEC on 2018-02-14. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

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© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

The text of document 100/2989/FDIS, future edition 2 of IEC 62731, prepared by IEC/TC 100 "Audio,

video and multimedia systems and equipment" was submitted to the IEC-CENELEC parallel vote and

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

The text of the International Standard IEC 62731:2018 was approved by CENELEC as a European

In the official version, for Bibliography, the following note has to be added for the standard indicated:

Warning! Make sure that you obtained this publication from an authorized distributor.

FOREWORD ........................................................................................................................... 3

1 Scope .............................................................................................................................. 5

2 Normative references ...................................................................................................... 5

3 Terms, definitions and abbreviated terms ........................................................................ 5

3.1 Terms and definitions .............................................................................................. 5

3.2 Abbreviated terms ................................................................................................... 6

4 Guiding principles and conventions ................................................................................. 7

5 User requirements of visually impaired people ................................................................. 7

5.1 Users' needs ........................................................................................................... 7

5.2 Navigating channels ................................................................................................ 8

5.3 Navigating TV inputs ............................................................................................... 8

5.4 Additional data services .......................................................................................... 8

5.5 Operating the TV .................................................................................................... 8

5.6 TV use .................................................................................................................... 8

6 Functional requirements .................................................................................................. 9

6.1 Functionality for TV, TTS device combination ......................................................... 9

6.2 Functionality: TTS device/engine .......................................................................... 10

6.3 Functionality: TV ................................................................................................... 10

6.4 Setting up: TV, TTS device combination ................................................................ 11

7 TV events and TTS data ................................................................................................ 11

7.1 TV context and events .......................................................................................... 11

7.2 TTS data per event ............................................................................................... 12

7.2.1 Details ........................................................................................................... 12

7.2.2 Channel change ............................................................................................ 12

7.2.3 Additional information .................................................................................... 13

7.2.4 Navigation and selection ................................................................................ 13

7.2.5 Context switch ............................................................................................... 14

7.2.6 Pop-up message ............................................................................................ 16

8 TTS profiles ................................................................................................................... 16

8.1 Basic profile .......................................................................................................... 16

8.2 Main profile ........................................................................................................... 16

8.3 Enhanced profile ................................................................................................... 17

8.4 Summary .............................................................................................................. 18

Bibliography .......................................................................................................................... 19

Figure 1 – TV – TTS device system diagram ........................................................................... 9

Figure 2 – Context event state diagram ................................................................................. 12

Table 1 – Overview of profiles ............................................................................................... 18

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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 62731 has been prepared by IEC technical committee 100: Audio,

This second edition cancels and replaces the first edition published in 2013. This edition

This edition includes the following significant technical changes with respect to the previous

a) in 6.2, the levels of announcement quality were revised as well as considerations for ways

b) in 6.3, the following TV functionality was added: the TV can receive updated words,

associated conversions and updated conversion rules for the TTS engine via a network

Full information on the voting for the approval of this International Standard can be found in

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

This International Standard specifies the text-to-speech functionality for a (broadcast) receiver

with a text-to-speech system. Such a system may be one device, i.e. a receiver with an

integrated text-to-speech generator, or may be two devices, i.e. a receiver interfacing with an

external text-to-speech device. This document applies only to completely functional stationary

(or semi-stationary) digital TV receivers such as set top boxes, integrated digital TVs,

recorders and other products whose primary function is to receive TV content. Where this

This document does not apply to products that are capable of receiving TV as a secondary

function (e.g. PCs or game consoles with digital television receivers). It also does not apply to

ISO and IEC maintain terminological databases for use in standardization at the following

filter that organises or reduces the list of displayed EPG items according to certain criteria

• programmes for a given time period (for instance "today", "tomorrow", "next 7 days").

sequence of programmes under the control of a broadcaster which can be broadcast as part

textual representation of the dialogue (and frequently additional auditory information),

Note 1 to entry: Subtitles can be a textual rendering in the same language as the spoken dialogue, or can provide

Note 2 to entry: In some parts of the world, subtitles are called "(closed) captions", and subtitling is referred to as

Note 1 to entry: If the TV uses an external TTS converter, TTS audio is interpreted as TTS data.

audio information for immediate output typically related to emergency information

This document describes the required basic behaviour for a TV text-to-speech combination in

a basic profile, but also provides for enhanced profiles. It also gives a short introduction into

the basic problems of visually impaired people: i.e. what are the problems visually impaired

Providing text-to-speech functionality for a broadcast receiver, for example a TV or an STB,

can be of great help to (visually) disabled people. Such speech functionality may be

integrated in the receiver or may be external to the receiver in a separate device.

In general as the guiding principle, when building a TTS interface in the context of this

document, implementers should aspire to achieve functional equivalence of the user

experience. This means that a person operating the device using the speech interface should

have access to similar information and be able to accomplish tasks similar to those they

• basic functional description for a TV-TTS device combination or TV with integrated TTS;

In this document, mandatory requirements are specified; optional and informative features are

A claim of conformity with this document requires conformity with all mandatory requirements.

A TV-TTS device combination or a TV with a TTS that is integrated may provide options for a

user to enable or disable each feature of a product. While options for user configurations may

This subclause explains the needs of visually impaired people as the primary target users for

a TV with TTS. Unless these needs are met, the system is not accessible to this user group.

Visually impaired people experience access barriers in the course of the following activities

f) using additional data (text) services provided by the broadcaster, e.g. an EPG;

Items a), b) and c) are outside the scope of this document. Item c) further relates to the fact

that, in some countries, foreign language programmes are translated via subtitles. For users

who cannot see the subtitles, supplementary audio services are sometimes used to deliver an

audio version of the subtitles. This document elaborates on the remaining four items, i.e. d),

NOTE 1 For DVB systems, item a) is already solved by audio description. Also, the use case of providing

supplementary audio services to deliver an audio version of the subtitles is covered in the DVB-SI specification

NOTE 2 For ATSC systems, the audio system includes a visually impaired (VI) associate service, which allows a

complete programme mix containing music, effects, dialogue, and additionally a narrative description of the picture

The problem is that a user does not know which channel the TV displays, i.e. the user gets

"lost during navigation". The TV is displaying navigation data on the screen but the user is

The problem is that a user is unable to select the required input to the TV, e.g. the user

wishes to select DTV or a specific external input linked to a recording or other device. The

With digital TV, a broadcaster may transmit additional data (text) services to augment TV

programming, provide additional information on programming, or provide news. Such

The items above are listed in order of importance with the most important item appearing first.

It is noted that this data provides additional convenience in using the TV, but that is non-

User settings are another needed function besides navigation. This can be done through

buttons on the remote control (out of scope of this specification), but also via on-screen

menus. For visually impaired people, on-screen menus are typically of little use.

A distinction exists between initial setup and daily operation of the TV. Initial setup is typically

a one-time operation during the lifetime of a TV. Daily operation is more frequent and more

important. Consequently, a distinction among menu items for daily operation exists, those

addressing specific accessibility functions, and TV setup menu items. However, the most

Use characterization of a TV helps in determining implementation profiles. Navigating

channels, for example, is done most often when watching TV, as well as commands such as

volume up and down. This may be supported by additional data services, but does not affect

the primary functions of the TV. Changing the TV's system settings is not done very often,

except perhaps for changing sound or video settings or switching audio description on and off.

Such settings may have an easy access mode through a special menu. TV installation is

typically performed only once during the lifetime of the TV. Often, visually impaired people

can benefit from specialized support for installing the TV, i.e. it is part of the service when

buying a new TV. Understanding this life- and usage cycle of a TV helps with defining the

most effective and efficient solutions and is reflected in the profiles. In the following

paragraphs, we refer to "basic", "main" and "enhanced" profiles, which are further defined and

Key operations for a minimum TTS implementation on a receiver for TV use are as set out in

a) channel number, name and event information – key for a user to identify which service

b) availability of audio description – key for a user to know about the availability of this

c) availability of subtitles – key for a user to know about the availability of this service

d) basic EPG – allow the user to navigate through the EPG, if such data is present in the

e) context changes – key for a user to understand if the TV went to another state or when a

Additional operations that shall be included in the main profile, in addition to all those in the

f) receiver menu functions allows the user to navigate receiver operations and functions.

Additional operations that shall be included in the enhanced profile, in addition to all those

h) additional EPG data – allows the user to get more info on the service or event;

i) operations of a recording device – allows the user to record future events, possibly

The TV-TTS device system diagram is illustrated in Figure 1. As shown in the figure, the TTS

device is a separate function from the TV, which can be implemented on a device connected

• the delay between an event and the resulting TTS audio related to that event shall be such

• the user should be able to move to the next operation even in the middle of currently

• the language of the TTS audio shall be the same as set for the TV’s UI, except when

signalled differently; the TTS device/engine may choose to pronounce the text or to

• TTS audio may not need to literally represent the related visual information on the screen

• priority audio information shall overrule currently playing TTS audio information.

NOTE For example, EAS (Emergency Alert System) [USA] or EWS (Emergency Warning System) [JPN] are higher

• an external TTS device should be designed to be fully accessible to visually impaired

• the volume level of the TTS device/engine shall be changeable by the user: the TTS

device shall announce the new volume level; it should be possible to do this independently

• the user should be able to adjust speech characteristics like speed, pitch, voice type,

• the TTS engine should announce abbreviations in a manner suited to the context, for

example: "IEC" should be announced "I E C"; and "IEEE" should be announced "I triple E".

The TTS engine may also pronounce common acronyms in full, e.g. "sub" could be spoken

• the TTS engine should announce numbers in a manner suited to the context, e.g. as a

• the TTS engine should announce proper nouns (e.g. names, place names) correctly;

• levels of announcement quality are at the discretion of the implementers; the following are

– consider ways to update the vocabulary database and conversion rules of the TTS

– consider provision of additional information (= metadata) to help the TTS engine for

– consider ways in which device users can provide service providers with feedback on

The TV determines the user interface, i.e. what is displayed on the screen, and how the TV

interacts with the user. The TV therefore also determines which text is sent to the TTS engine.

The TV can receive updated words, associated conversions and updated conversion rules for

The user should be able to control, via the TV TTS, settings such as volume, speed, pitch,