Dubbing and Audio description Profiles of TTML2

Abstract

This specification defines DAPT , a TTML -based file format for the exchange of timed text content in dubbing and audio description workflows.

This section is non-normative.

In general usage, one meaning of the word script is the written text of a film, television programme, play etc. A script can be either a record of the completed production, also known as a transcript, or as a plan for a yet to be created production. In this document, we use domain-specific terms, and define more specifically that:

a transcript is the text representation of pre-existing media in another form, for example the dialogue in a video;
a script is a text representation of the intended content of media prior to its creation, for example to guide an actor in recording an audio track.

The term DAPT script is used generically to refer to both transcripts and scripts , and is a point of conformance to the formal requirements of this specification. DAPT Scripts consist of timed text and associated metadata, such as the character speaking.

In dubbing workflows, a transcript is generated and translated to create a script . In audio description workflows, a transcript describes the video image, and is then used directly as a script for recording an audio equivalent.

DAPT is a TTML -based format for the exchange of transcripts and scripts (i.e. DAPT Scripts ) among authoring, prompting and playback tools in the localization and audio description pipelines. A DAPT document is a serializable form of a DAPT Script designed to carry pertinent information for dubbing or audio description such as type of DAPT script , dialogue, descriptions, timing, metadata, original language transcribed text, translated text, language information, and audio mixing instructions, and to be extensible to allow user-defined annotations or additional future features.

This specification defines the data model for DAPT scripts and its representation as a [ TTML2 ] document (see 4. DAPT Data Model and corresponding TTML syntax ) with some constraints and restrictions (see 5. Constraints ).

A DAPT script is expected to be used to make audio visual media accessible or localized for users who cannot understand it in its original form, and to be used as part of the solution for meeting user needs involving transcripts , including accessibility needs described in [ media-accessibility-reqs ], as well as supporting users who need dialogue translated into a different language via dubbing.

Every part of the DAPT script content is required to be marked up with some indication of what it represents in the related media, via the Represents property; likewise the DAPT Script as a whole is required to list all the types of content that it represents, for example if it represents audio content or visual content, and if visual, then if it represents text or non-text etc. A registry of hierarchical content descriptors is provided.

The authoring workflow for both dubbing and audio description involves similar stages, that share common requirements as described in [ DAPT-REQS ]. In both cases, the author reviews the content and writes down what is happening, either in the dialogue or in the video image, alongside the time when it happens. Further transformation processes can change the text to a different language and adjust the wording to fit precise timing constraints. Then there is a stage in which an audio rendering of the script is generated, for eventual mixing into the programme audio. That mixing can occur prior to distribution, or in the player directly.

The dubbing process which consists in creating a dubbing script is a complex, multi-step process involving:

Transcribing and timing the dialogue in its own language from a completed programme to create a transcript ;
Notating dialogue with character information and other annotations;
Generating localization notes to guide further adaptation;
Translating the dialogue to a target language script ;
Adapting the translation to the dubbing; for example matching the actor’s lip movements in the case of dubs.

A dubbing script is a transcript or script (depending on workflow stage) used for recording translated dialogue to be mixed with the non-dialogue programme audio, to generate a localized version of the programme in a different language, known as a dubbed version, or dub for short.

Dubbing scripts can be useful as a starting point for creation of subtitles or closed captions in alternate languages. This specification is designed to facilitate the addition of, and conversion to, subtitle and caption documents in other profiles of TTML , such as [ TTML-IMSC1.2 ], for example by permitting subtitle styling syntax to be carried in DAPT documents . Alternatively, styling can be applied to assist voice artists when recording scripted dialogue.

Creating audio description content is also a multi-stage process. An audio description , also known as video description or in [ media-accessibility-reqs ] as described video , is an audio service to assist viewers who can not fully see a visual presentation to understand the content. It is the result of mixing the main programme audio with the audio rendition of each description , authored to be timed when it does not clash with dialogue, to deliver an audio description mixed audio track. Main programme audio refers to the audio associated with the programme prior to any further mixing. A description is a set of words that describes an aspect of the programme presentation, suitable for rendering into audio by means of vocalisation and recording or used as a text alternative source for text to speech translation, as defined in [ WCAG22 ]. More information about what audio description is and how it works can be found at [ BBC-WHP051 ].

Writing the audio description script typically involves:

watching the video content of the programme, or series of programmes,
identifying the key moments during which there is an opportunity to speak descriptions,
writing the description text to explain the important visible parts of the programme at that time,
creating an audio version of the descriptions, either by recording a human actor or using text to speech,
defining mixing instructions (applied using [ TTML2 ] audio styling) for combining the audio with the programme audio.

The audio mixing can occur prior to distribution of the media, or in the client. If the audio description script is delivered to the player, the text can be used to provide an alternative rendering, for example on a Braille display, or using the user's configured screen reader.

DAPT Scripts can be useful in other workflows and scenarios. For example, Original language transcripts could be used as:

the output format of a speech to text system, even if not intended for translation, or for the production of subtitles or captions;
a document known in the broadcasting industry as a "post production script", used primarily for preview, editorial review and sales purposes;

Both Original language transcripts and Translated transcripts could be used as:

an accessible transcript presented alongside audio or video in a web page or application; in this usage, the timings could be retained and used for synchronisation with, or navigation within, the media or discarded to present a plain text version of the entire timeline.

The top level structure of a document is as follows:

The <tt> root element in the namespace http://www.w3.org/ns/ttml indicates that this is a TTML document and the ttp:contentProfiles attribute indicates that it adheres to the DAPT content profile defined in this specification.
The daptm:scriptRepresents attribute indicates what the contents of the document are an alternative for, within the original programme.
The daptm:scriptType attribute indicates the type of transcript or script but in this empty example, it is not relevant, since only the structure of the document is shown.
The daptm:langSrc attribute indicates the default text language source, for example the original language of the content, while the xml:lang attribute indicates the default language in this script, which in this case is the same. Both of these attributes are inherited and can be overridden within the content of the document.

The structure is applicable to all types of DAPT scripts , dubbing or audio description .

Example 1

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-top-level.xml</pre>
</body>

</

html

>

The following examples correspond to the timed text transcripts and scripts produced at each stage of the workflow described in [ DAPT-REQS ].

The first example shows an early stage transcript in which timed opportunities for descriptions or transcriptions have been identified but no text has been written; the daptm:represents attribute present on the <body> element here is inherited by the <div> elements since they do not specify a different value:

Example 2

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-times-only.xml</pre>
</body>

</

html

>

The following examples will demonstrate different uses in dubbing and audio description workflows.

When descriptions are added this becomes a Pre-Recording Script . Note that in this case, to reflect that most of the audio description content transcribes the video image where there is no inherent language, the Text Language Source , represented by the daptm:langSrc attribute, is set to the empty string at the top level of the document. It would be semantically equivalent to omit the attribute altogether, since the default value is the empty string:

Example 3

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-times-and-text.xml</pre>
</body>

</

html

>

Audio description content often includes text present in the visual image, for example if the image contains a written sign, a location, etc. The following example demonstrates such a case: Script Represents is extended to show that the script 's contents represent textual visual information in addition to non-textual visual information. Here a more precise value of Represents is specified on the Script Event to reflect that the text is in fact a location, which is allowed because the more precise value is a sub-type of the new value in Script Represents . Finally, since the text has an inherent language, the Text Language Source is set to reflect that language.

Example 4

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-times-and-text-with-visual-text.xml</pre>
</body>

</

html

>

After creating audio recordings, if not using text to speech, instructions for playback mixing can be inserted. For example, The gain of "received" audio can be changed before mixing in the audio played from inside the <span> element, smoothly animating the value on the way in and returning it on the way out:

Example 5

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-script-with-gain.xml</pre>
</body>

</

html

>

At the document level, the daptm:scriptRepresents attribute indicates that the document represents both visual text and visual non-text content in the related media. It is possible that there are no Script Events that actually represent visual text, for example because there is no text in the video image.

In the above example, the <div> element's begin attribute defines the time that is the "syncbase" for its child, so the times on the <animate> and <span> elements are relative to 25s here. The first <animate> element drops the gain from 1 to 0.39 over 0.3s, freezing that value after it ends, and the second one raises it back in the final 0.3s of this description. Then the <span> element is timed to begin only after the first audio dip has finished.

If the audio recording is long and just a snippet needs to be played, that can be done using clipBegin and clipEnd. If we just want to play the part of the audio from file from 5s to 8s it would look like:

Example 6

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-script-with-audio-clipped.xml</pre>
</body>

</

html

>

Or audio attributes can be added to trigger the text to be spoken:

Example 7

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-script-with-speak.xml</pre>
</body>

</

html

>

It is also possible to embed the audio directly, so that a single document contains the script and recorded audio together:

Example 8

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-script-with-embedded-audio.xml</pre>
</body>

</

html

>

From the basic structure of Example 1 , transcribing the audio produces an original language dubbing transcript , which can look as follows. No specific style or layout is defined, and here the focus is on the transcription of the dialogue. Characters are identified within the <metadata> element. Note that the language and the text language source are defined using xml:lang and daptm:langSrc attributes respectively, which have the same value because the transcript is not translated.

Example 9

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-original-language.xml</pre>
</body>

</

html

>

After translating the text, the document is modified. It includes translation text, and in this case the original text is preserved. The main document's default language is changed to indicate that the focus is on the translated language. The combination of the xml:lang and daptm:langSrc attributes are used to mark the text as being original or translated. In this case, they are present on both the <tt> and <p> elements to make the example easier to read, but it would also be possible to omit them in some cases, making use of the inheritance model:

Example 10

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-original-language-with-dub-language.xml</pre>
</body>

</

html

>

The process of adaptation, before recording, could adjust the wording and/or add further timing to assist in the recording. The daptm:scriptType attribute is also modified, as in the following example:

Example 11

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/intro-original-language-with-dub-language-and-adaptation.xml</pre>
</body>

</

html

>

This section specifies the data model for DAPT and its corresponding TTML syntax. In the model, there are objects which can have properties and be associated with other objects. In the TTML syntax, these objects and properties are expressed as elements and attributes, though it is not always the case that objects are expressed as elements and properties as attributes.

Figure 1 illustrates the DAPT data model, hyperlinking every object and property to its corresponding section in this document. Shared properties are shown in italics. All other conventions in the diagram are as per [ uml ].

Error



Cannot


GET

/uploads/kKtNbK/figures/

/uploads/

HLKPCi

/figures/


class

-diagram.

svg

Figure 1 (Informative) Class diagram showing main entities in the DAPT data model.

Issue 116 : Add non-inlined embedded audio resources to the Data Model? question PR-must-have

See also #115 - if we are going to support non-inline embedded audio resources, should we make an object for them and add it into the Data Model?

A DAPT Script is a transcript or script that corresponds to a document processed within an authoring workflow or processed by a client, and conforms to the constraints of this specification. It has properties and objects defined in the following sections: Script Represents , Script Type , Default Language , Text Language Source , Script Events and, for Dubbing Scripts , Characters .

A DAPT Document is a [ TTML2 ] timed text content document instance representing a DAPT Script . A DAPT Document has the structure and constraints defined in this and the following sections.

Note

A [ TTML2 ] timed text content document instance has a root <tt> element in the TT namespace.

The Script Represents property is a mandatory property of a DAPT Script which indicates which components of the related media object the contents of the document represent. The contents of the document could be used as part of a mechanism to provide an accessible alternative for those components.

Note

Script Events have a related property, Represents , and there are constraints about the permitted values of that property that are dependent on the values of Script Represents .

To represent this property, the daptm:scriptRepresents attribute MUST be present on the <tt> element, with a value conforming to the following syntax:

daptm:scriptRepresents
: <content-descriptor> ( <lwsp>+ <content-descriptor>)*

<lwsp>

#
as
TTML2

The Default Language is a mandatory property of a DAPT Script which represents the default language for the Text content of Script Events . This language may be one of the original languages or a Translation language. When it represents a Translation language, it may be the final language for which a dubbing or audio description script is being prepared, called the Target Recording Language or it may be an intermediate, or pivot, language used in the workflow.

The Default Language is represented in a DAPT Document by the following structure and constraints:

the xml:lang attribute MUST be present on the <tt> element and its value MUST NOT be empty.

Note

All text content in a DAPT Script has a specified language. When multiple languages are used, the Default Language can correspond to the language of the majority of Script Events , to the language being spoken for the longest duration, or to a language arbitrarily chosen by the author.

Example 13

An Original Language Transcript of dialogue is prepared for a video containing dialogue in Danish and Swedish. The Default Language is set to Danish by setting


xml:lang="da"

on the


<tt>

element. Script Events that contain Swedish Text override this by setting


xml:lang="sv"

on the

<p>

element. Script Events that contain Danish Text can set the


xml:lang

attribute or omit it, since the inherited language is the Default Language of the document. In both cases the Script Events' Text objects are

<p>

elements that represent untranslated content that had an inherent language (in this case dialogue) and therefore set the



daptm:langSrc

attribute to their source language, implying that they are in the Original language.

The Script Type property is a mandatory property of a DAPT Script which describes the type of documents used in Dubbing and Audio Description workflows, among the following: Original Language Transcript , Translated Transcript , Pre-recording Script , As-recorded Script .

To represent this property, the daptm:scriptType attribute MUST be present on the <tt> element:

daptm:scriptType
  : "originalTranscript"
  | "translatedTranscript"
  | "preRecording"
|
"asRecorded"

The definitions of the types of documents and the corresponding daptm:scriptType attribute values are:

Original Language Transcript :
When the daptm:scriptType attribute value is originalTranscript, the document is a literal transcription of the dialogue and/or on-screen text in their inherent spoken/written language(s), or of non-dialogue sounds and non-linguistic visual content.

Script Events in this type of transcript :
- SHOULD contain Original Text objects;
- SHOULD NOT contain Translation Text objects.
Example 14
If a programme contains dialogue in English and Hebrew, the Original Language Transcript will contain some Script Events in English and some in Hebrew, all containing Original Text objects. The document contains no Translation Text objects.
Translated Transcript :
When the daptm:scriptType attribute value is translatedTranscript, the document represents a translation of the Original Language Transcript in a common language.

It can be adapted to produce a Pre-Recording Script , and/or used as the basis for a further translation into the Target Recording Language .

Script Events in this type of transcript :
- SHOULD contain Translation Text objects;
- MAY also contain Original Text objects.
Example 15
If a programme contains dialogue in English and Hebrew, the French Translated Transcript will contain at least the translation in French of all Script Events . It may still retain text content in Hebrew and English to assist further processing.

Example 16
If an audio description Original Language Transcript contains Original language Script Events that describe in-image text content, and the desired audio description output needs to be in a different language, the Text objects can be Translation Text objects. In that case, it is appropriate to mark the transcript as a Translated Transcript . It may also be appropriate, as part of the translation activity, to describe within the translated text content the original language of that text, to inform the audience, for example, "A Japanese newspaper headline that means: sailor completes ocean crossing".
Pre-recording Script :
When the daptm:scriptType attribute value is preRecording, the document represents the result of the adaptation of an Original Language Transcript or a Translated Transcript for recording, e.g. for better lip-sync in a dubbing workflow, or to ensure that the words can fit within the time available in an audio description workflow.

Script Events in this type of script :
- SHOULD contain Text objects in the Target Recording Language ;
- MAY also contain Original Text objects from the Original Language Transcript in the case that their language is not the Target Recording Language , for context, to assist further processing;
- SHOULD NOT contain Audio objects.
Note

The Script Type of a DAPT Script cannot necessarily be detected by inspecting the text content of the document. For example, the adaptation of a Translated Transcript into a Pre-recording Script can consist in replacing some words in the text content of a Script Event without altering the rest of the document. In either case, Translation Text objects have their Text Language Source properties set to the source language from which they were translated.

Note

The Original Text objects in Audio Description Script Events have an empty Text Language Source property if they represent visual elements of the scene that do not have an inherent language. Otherwise if they do represent visual elements with an inherent language, such as in-image text, they are required to have a Text Language Source that specifies a language. If audio description scripts are translated, their translations would be represented by Translation Text objects.
As-recorded Script :
When the daptm:scriptType attribute value is asRecorded, the document represents the actual audio recording.

Script Events in this type of script :
- SHOULD contain Text objects in the Target Recording Language ;
- MAY also contain Original Text objects from the Original Language Transcript or Translation Text objects in other languages for context and quality verification;
- MAY also contain links to audio and mixing instructions for the purpose of producing an audio track incorporating the recordings;
- SHOULD contain Audio Recording objects;
- SHOULD NOT contain Synthesized Audio objects.
Note

Translation Text objects within As-recorded Scripts retain their Text Language Source , so that the source language from which they were translated remains available.

Editor's note

The following example is orphaned - move to the top of the section, before the enumerated script types?

Example 17

<tt daptm:scriptType="originalTranscript">
...

</

tt

>

A DAPT Script MAY contain zero or more Script Event objects, each corresponding to dialogue, on screen text, or descriptions for a given time interval.

If any Script Events are present, the DAPT Document MUST have one <body> element child of the <tt> element.

A DAPT Script MAY contain zero or more Character objects, each describing a character that can be referenced by a Script Event .

If any Character objects are present, the DAPT Document MUST have one <head> element child of the <tt> element, and that <head> element MUST have at least one <metadata> element child.

Note

4.2 Character recommends that all the Character objects be located within a single <metadata> element parent, and in the case that there are more than one <metadata> element children of the <head> element, that the Character objects are located in the first such child.

Some of the properties in the DAPT data model are common within more than one object type, and carry the same semantic everywhere they occur. These shared properties are listed in this section.

Some of the value sets in DAPT are reused across more than one property, and have the same constraints everywhere they occur. These shared value sets are also listed in this section.

Editor's note

Would it be better to make a "Timed Object" class and subclass Script Event, Mixing Instruction and Audio Recording from it?

The following timing properties define when the entities that contain them are active:

The Begin property defines when an object becomes active, and is relative to the active begin time of the parent object. DAPT Scripts begin at time zero on the media timeline.
The End property defines when an object stops being active, and is relative to the active begin time of the parent object.
The Duration property defines the maximum duration of an object.

Note

If both an End and a Duration property are present, the end time is the earlier of End and Begin + Duration , as defined by [ TTML2 ].

Note

If any of the timing properties is omitted, the following rules apply, paraphrasing the timing semantics defined in [ TTML2 ]:

The default value for Begin is zero, i.e. the same as the begin time of the parent object.
The default value for End is indefinite, i.e. it resolves to the same as the end time of the parent timed object, if there is one.
The default value for Duration is indefinite, i.e. the end time resolves to the same as the end time of the parent object.

Note

The end time of a DAPT Script is for practical purposes the end of the Related Media Object .

The values permitted in the Script Represents and Represents properties depend on the < content-descriptor > syntactic definition and its associated registry table.

< content-descriptor > has a value conforming to the following syntax:

<content-descriptor>  # see registry table below
: <descriptor-token> ( <descriptor-delimiter> <descriptor-token> )*
<descriptor-token>
: (descriptorTokenChar)+
descriptorTokenChar  # xsd:NMtoken without the "."
: NameStartChar | "-" | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
<descriptor-delimiter>
:
"."
#
FULL
STOP
U+002E

< content-descriptor > has values that are delimiter separated ordered lists of tokens.

A < content-descriptor > value B is a content descriptor sub-type ( sub-type ) of another <content-descriptor> value A if A's ordered list of descriptor-tokens is present at the beginning of B's ordered list of descriptor-tokens .

Example 18

Table demonstrating example values of `< content-descriptor >` and whether each is a sub-type of the other.
`<content-descriptor>` A	`<content-descriptor>` B	Is B a sub-type of A?
`visual.text`	`visual`	No
`visual.text`	`visual.text`	Yes
`visual.text`	`visual.text.location`	yes

For example, in this table, A could be one of the values listed in Script Represents property, and B could be the value of a Represents property.

The permitted values for < content-descriptor > are either those listed in the following registry table , or can be user-defined.

Valid user-defined values MUST begin with x- or be sub-types of values in the content-descriptor registry table, where the first additional < descriptor-token > component begins with x-.

Registry table for the `< content-descriptor >` component whose Registry Definition is at H.2.2 `<content-descriptor>` registry table definition
`< content-descriptor >`	Status	Description	Example usage
`audio`	Provisional	Indicates that the DAPT content represents any part of the audio programme.	Dubbing, translation and hard of hearing subtitles and captions, pre- and post- production scripts
`audio.dialogue`	Provisional	Indicates that the DAPT content represents verbal communication in the audio programme, for example, a spoken conversation.	Dubbing, translation and hard of hearing subtitles and captions, pre- and post- production scripts
`audio.nonDialogueSounds`	Provisional	Indicates that the DAPT content represents a part of the audio programme corresponding to sounds that are not verbal communication, for example, significant sounds, such as a door being slammed in anger.	Translation and hard of hearing subtitles and captions, pre- and post- production scripts
`visual`	Provisional	Indicates that the DAPT content represents any part of the visual image of the programme.	Audio Description
`visual.dialogue`	Provisional	Indicates that the DAPT content represents verbal communication, within the visual image of the programme, for example, a signed conversation.	Dubbing or Audio Description, translation and hard of hearing subtitles and captions, pre- and post- production scripts
`visual.nonText`	Provisional	Indicates that the DAPT content represents non-textual parts of the visual image of the programme, for example, a significant object in the scene.	Audio Description
`visual.text`	Provisional	Indicates that the DAPT content represents textual content in the visual image of the programme, for example, a signpost, a clock, a newspaper headline, an instant message etc.	Audio Description
`visual.text.title`	Provisional	A sub-type of `visual.text` where the text is the title of the related media.	Audio Description
`visual.text.credit`	Provisional	A sub-type of `visual.text` where the text is a credit, e.g. the name of an actor.	Audio Description
`visual.text.location`	Provisional	A sub-type of `visual.text` where the text indicates the location where the content is occurring.	Audio Description

Some entities in the data model include unique identifiers. A Unique Identifier has the following requirements:

it is unique within the DAPT Script , i.e. the value of a Unique Identifier can only be used one time within the document, regardless of which specific kind of identifier it is.

If a Character Identifier has the value "abc" and a Script Event Identifier in the same document has the same value, that is an error.
its value has to conform to the requirements of Name as defined by [ XML ]
Note
It cannot begin with a digit, a combining diacritical mark (an accent), or any of the following characters:
```
    .
    -
    ·  // #xB7
    ‿  // #x203F
⁀

//
#x2040
```
but those characters can be used elsewhere.

A Unique Identifier for an entity is expressed in a DAPT Document by an xml:id attribute on the corresponding element.

Note

The formal requirements for the semantics and processing of xml:id are defined in [ xml-id ].

This section is mainly relevant to Dubbing workflows.

A character in the programme can be described using a Character object which has the following properties:

a mandatory Character Identifier which is a Unique Identifier used to reference the character from elsewhere in the document, for example to indicate when a Character participates in a Script Event .
a mandatory Name which is the name of the Character in the programme
an optional Talent Name , which is the name of the actor speaking dialogue for this Character .

A Character is represented in a DAPT Document by the following structure and constraints:

The Character is represented in a DAPT Document by a <ttm:agent> element present at the path /tt/head/metadata/ttm:agent, with the following constraints:
- The type attribute MUST be set to character.
- The xml:id attribute MUST be present on the <ttm:agent> element and set to the Character Identifier .
- The <ttm:agent> element MUST contain a <ttm:name> element with its type attribute set to alias and its content set to the Character Name .
- If the Character has a Talent Name , it MUST contain a <ttm:actor> child element. That child element MUST have an agent attribute set to the value of the xml:id attribute of a separate <ttm:agent> element corresponding to the Talent Name , that is, whose type attribute is set to person.
  
  Note
  
  The requirement for an additional <ttm:agent> element corresponding to the Talent Name is defined in the following bullet list.
Example 19
```
...
<metadata>
  <ttm:agent type="character" xml:id="character_1">
    <ttm:name type="alias">DESK CLERK</ttm:name>
  </ttm:agent>
</metadata>
...
```
Example 20
```
...
<metadata>
  <ttm:agent type="person" xml:id="actor_A">
    <ttm:name type="full">Matthias Schoenaerts</ttm:name>
  </ttm:agent>
  <ttm:agent type="character" xml:id="character_2">
    <ttm:name type="alias">BOOKER</ttm:name>
    <ttm:actor agent="actor_A"/>
  </ttm:agent>
</metadata>
...
```
If the Character has a Talent Name property:
- A <ttm:agent> element corresponding to the Talent Name MUST be present at the path /tt/head/metadata/ttm:agent, with the following constraints:
  - its type attribute MUST be set to person
  - its xml:id attribute MUST be set.
  - it MUST have a <ttm:name> child element whose type MUST be set to full and its content set to the Talent Name
- If more than one Character is associated with the same Talent Name there SHOULD be a single <ttm:agent> element corresponding to that Talent Name , referenced separately by each of the Characters .
- Each <ttm:agent> element corresponding to a Talent Name SHOULD appear before any of the Character <ttm:agent> elements whose <ttm:actor> child element references it.
All <ttm:agent> elements SHOULD be contained in the first <metadata> element in the <head> element.

Note

There can be multiple <metadata> elements in the <head> element, for example to include proprietary metadata but the above recommends that only one is used to define the characters.

Editor's note

The group is considering updating the rule(s) around which metadata element is used to carry DAPT information. The group would like to balance simplicity of implementation (e.g. locating the DAPT metadata in one place) vs. flexibility of authoring (e.g. having different metadata elements for series vs episodes). One approach is the current one: "only one metadata element, the first one". Another approach is "only one metadata element, identified by an attribute". Another approach is "any number of metadata elements". The group welcomes feedback from implementers and users.

Note

As indicated in 5.2.1 Unrecognised vocabulary ,


ttm:agent

elements can have foreign attributes and elements. This can be used to provide additional, proprietary character information.

Issue 44 : Define DAPT-specific conformant implementation types CR must-have

We should define our own classes of conformant implementation types, to avoid using the generic "presentation processor" or "transformation processor" ones. We could link to them.
At the moment, I can think of the following classes:

DAPT Authoring Tool: tool that produces compliant DAPT documents or consumes DAPT compliant document. I don't think they map to TTML2 processors.
DAPT Audio Recorder/Renderer: tool that takes DAPT Audio Description scripts, e.g. with mixing instruction, and produces audio output, e.g. a WAVE file. I think it is a "presentation processor"
DAPT Validator: tool that verify that a DAPT document is compliant to the specification. I'm not sure what it maps to in TTML2 terminology.

A Script Event object represents dialogue, on screen text or audio descriptions to be spoken and has the following properties:

A mandatory Script Event Identifier which is a Unique Identifier .
An optional Begin property and an optional End and an optional Duration property that together define the Script Event 's time interval in the programme timeline

Note

Typically Script Events do not overlap in time. However, there can be cases where they do, e.g. in Dubbing Scripts when different Characters speak different text at the same time.
A Represents property used to identify what content the event represents (e.g. dialogue, on screen text, etc.). Every Script Event MUST have a valid Represents property.

Note

The Represents property is inheritable, so the value does not need to be specified on every Script Event explicitly.
Zero or more Character Identifiers indicating the Characters involved in this Script Event .

Note

While typically, a Script Event corresponds to one single Character , there are cases where multiple characters can be associated with a Script Event . This is when all Characters speak the same text at the same time.

Note

In a transcript , when the event corresponds to in-image content, for example an audio description , no Character Identifier is needed. However it may be helpful in a Pre-recording Script or an As-recorded Script context to indicate a Character signifying who voices the recording.
Zero or more Text objects, each being either Original or Translation .

Note

A Script Event with no Text objects can be created as part of an initial phase of authoring, in workflows where it is helpful to block out the time intervals during which some content could be present. For example, an empty Script Event with timing properties can be created to identify an opportunity for creating an audio description. See also [ DAPT -REQS] Process Step 1 .

Note

Empty Text objects, i.e. ones that have no text content, can be used to indicate explicitly that there is no text content. It is recommended that empty Text objects are not used as a workflow placeholder to indicate incomplete work.
zero or more Script Event Description objects, each being a human-readable description of the Script Event .
an optional On Screen property, which is an annotation indicating the position of the subject (e.g. a character ) of the Script Event
Zero or more Mixing Instruction objects used to adjust playback of the programme audio during the Script Event .

A Script Event is represented in a DAPT Document at the path /tt/head/body//div, with the following structure and constraints:

Issue 233 : Consider improving identification of divs corresponding to script events CR must-have

Based on discussion at #216 (comment) , I think we should have an explicit signal to indicate when a div represents a Script Event.

There MAY be any number of nested <div> element ancestors in the path between the <body> element and the <div> element corresponding to the Script Event . No further semantic is defined for such elements.
There MUST be one <div> element corresponding to the Script Event , with the following constraints:
- The xml:id attribute MUST be present containing the Script Event Identifier .
- The begin, end and dur attributes represent respectively the Begin , End and Duration of the Script Event .
  
  The begin and end attributes SHOULD be present. The dur attribute MAY be present.
  
  Note
  
  See 4.1.6.1 Timing Properties for additional notes on timing properties.
- The ttm:agent attribute MAY be present and if present, MUST contain a reference to each ttm:agent attribute that represents an associated Character .
  
  Note
  
  Multiple references are specified using a space-separated list.
  Example 21
```
...
<div xml:id="event_1"
     begin="9663f" end="9682f" 
     ttm:agent="character_4">
...
</div>
...
```
- The daptm:represents attribute MAY be present representing the Represents property.
  Example 22
```
...
<div xml:id="event_1"
     begin="9663f" end="9682f" 
     daptm:represents="audio.dialogue">
...
</div>
...
```
- The computed value of the the daptm:represents attribute MUST be a valid non-empty value.
  
  Note
  
  It is possible to specify the daptm:represents attribute on an ancestor element, since Represents is an inheritable property.
- It MAY contain zero or more <p> elements representing each Text object.
- It MAY contain a <metadata> element representing the On Screen property.
- It MUST NOT contain any <div> element children.

The Text object contains text content typically in a single language. This language may be the Original language or a Translation language.

Text is defined as Original if it is any of:

the same language as the dialogue that it represents in the original programme audio;
a transcription of text visible in the programme video, in the same language as that text;
an untranslated representative of non-dialogue sound;
an untranslated description of the scene in the programme video.

Note

Text is defined as Translation if it is a representation of an Original Text object in a different language.

Text can be identified as being Original or Translation by inspecting its language and its Text Language Source together, according to the semantics defined in Text Language Source .

The source language of Translation Text objects and, where applicable, Original Text objects is indicated using the Text Language Source property.

A Text object may be styled.

Zero or more Mixing Instruction objects used to modify the programme audio during the Text MAY be present.

A Text object is represented in a DAPT Document by a <p> element at the path /tt/head/body//div/p, with the following constraints:

The Text of the Script Event is represented by the character content of the <p> element and of all of its <span> descendant elements, after <metadata> elements and foreign elements have been pruned, after replacing <br> elements by line breaks, and after applying White Space Handling as defined in [ XML ].

Note

The text content of the paragraph can be structured using TTML elements such as <br> or <span> which can include or reference TTML style attributes such as tts:ruby used to alter the layout or styling of sections of text within each paragraph. Mixed direction text, for example interleaved left to right (ltr) and right to left (rtl) text, can be specified by using the tts:direction attribute on <span> elements. Similarly metadata can be added using attributes or <metadata> elements.
The <p> element SHOULD have a daptm:langSrc attribute representing the Text object's Text Language Source , that is, indicating whether the Text is Original or a Translation and if its source had an inherent language.

Note

If a <p> element omits the daptm:langSrc attribute then its computed value is derived by inheritance from its parent element, and so forth up to the root <tt> element.

In scripts that have very little variation in source language, the daptm:langSrc attribute can be set on the root element and omitted from <p> elements except where its value differs.

Care should be taken if using this approach, especially when moving between Script Types , because changing it at the root element could affect the interpretation of descendant elements unexpectedly. In tools that allow fine-grained control, authors can mitigate this risk by explicitly setting the daptm:langSrc attribute on all <p> elements.

Implementers should take care to ensure that, when changing the daptm:langSrc attribute on an element, they check down the tree and if appropriate specify the attribute on descendant elements so that their meaning does not change unintentionally.

Note

A document that does not specify the daptm:langSrc attribute at all implies that all of the text is a transcript of content with no inherent language, for example audio description where no in-image text is transcribed, and which has not been translated.
The <p> element SHOULD have an xml:lang attribute corresponding to the language of the Text object.

Note

If a <p> element omits the xml:lang attribute then its computed language is derived by inheritance from its parent element, and so forth up to the root <tt> element, which is required to set the Default Language via its xml:lang attribute.

Care should be taken if changing the Default Language of a DAPT Script in case doing so affects descendant elements unexpectedly. In tools that allow fine-grained control, authors can mitigate this risk by explicitly setting the xml:lang attribute on all <p> elements.

Implementers should take care to ensure that, when changing the xml:lang attribute on an element, they check down the tree and if appropriate specify the attribute on descendant elements so that their meaning does not change unintentionally.
Example 23
```
<div xml:id="event_3"
     begin="9663f" end="9682f" 
     ttm:agent="character_3">
  <p xml:lang="pt-BR">Você vai ter.</p>
  <p xml:lang="fr" daptm:langSrc="pt-BR">Bah, il arrive.</p>

</

div

>
```
Note

In some cases, a single section of untranslated dialogue can contain text in more than one language. Rather than splitting a Script Event into multiple Script Events to deal with this, Text objects in one language can also contain some words in a different language. This is represented in a DAPT Document by setting the xml:lang and daptm:langSrc attributes on inner <span> elements.

Note

<span> elements can be used to add specific timing as illustrated in Example 10 to indicate the timing of the audio rendering of the relevant section of text. Per [ TTML2 ], timing of the <span> element is relative to the parent element's computed begin time.
It MAY contain zero or more <audio> elements representing each Audio Recording object.
It MAY contain zero or more <animate> elements representing each Mixing Instruction object.

The Text Language Source property is an annotation indicating the source language of a Text object, if applicable, or that the source content had no inherent language:

If it is empty, the Text represents content without an inherent language, such as untranslated descriptions of a visual scene or captions representing non-dialogue sounds.
Otherwise (if it is not empty):
- if its value is the same as the language of the Text object, the Text is Original .
- otherwise (if the value is different to the language of the Text ), the Text is a Translation , whose source language is the Text Language Source property's value.

Text Language Source is an inheritable property.

The Text Language Source property is represented in a DAPT Document by a daptm:langSrc attribute with the following syntax, constraints and semantics:

daptm:langSrc
: <empty-string> | <language-identifier>
<empty-string>
: ""                    # default
<language-identifier>
#
valid
BCP-47
language
tag

The value MUST be an empty string or a language identifier as defined by [ BCP47 ].
The default value is the empty string.
It applies to <p> and <span> elements.
It MAY be specified on the following elements: <tt>, <p> and <span>.
The inheritance model of the daptm:langSrc attribute is as follows:
- If it is present on an element, the computed value is the specified value.
- Otherwise (if it is not present on an element), the computed value of the attribute on that element is the computed value of the same attribute on the element's parent, or if the element has no parent it is the default value.
Note

The inheritance model of the daptm:langSrc attribute is intended to match the inheritance model of the xml:lang attribute [ XML ].
The semantics of the computed value are as follows:
- If the computed value is the empty string then it indicates that the Text is Original and sourced from content without an inherent language.
- Otherwise (the computed value is not empty)
  - if the computed value is the same as the computed value of the xml:lang attribute, then it indicates that the Text is Original and sourced from content with an inherent language.
  - Otherwise (the computed value differs from the computed value of the xml:lang attribute), it indicates that the Text is a translation , and the computed value is the language from which the Text was translated.

Note

An example of the usage of Text Language Source in a document is present in the Text section.

Example 24

Table enumerating example values of the `xml:lang` and `daptm:langSrc` attributes for different Original transcript sources and their inherent languages.
Transcript source	Inherent language of the transcript source	`xml:lang`	`daptm:langSrc`
In-image text	English	`en`	`en`
Video image (non text)	none	`en`	empty
Sound effect	none	`en`	empty
Dialogue	Arabic	`ar`	`ar`

If any of these transcripts were translated, the resulting Text would have its daptm:langSrc attribute set to the computed value of the xml:lang attribute of the source.

For example, if the Arabic dialogue were translated into Japanese, it would result in xml:lang="ja" and daptm:langSrc="ar".

The On Screen property is an annotation indicating the position in the scene relating to the subject of a Script Event , for example of the character speaking:

ON - the Script Event 's subject is on screen for the entire duration
OFF - the Script Event 's subject is off screen for the entire duration
ON_OFF - the Script Event 's subject starts on screen, but goes off screen at some point
OFF_ON - the Script Event 's subject starts off screen, but goes on screen at some point

If omitted, the default value is "ON".

Note

When the


daptm:represents

attribute value begins with


visual

the subject of each Script Event , i.e. what is being described, is expected to be in the video image, therefore the default of "ON" allows the property to be omitted in those cases without distortion of meaning.

The On Screen property is represented in a DAPT Document by a daptm:onScreen attribute on the <div> element, with the following constraints:

The following attribute corresponding to the On Screen Script Event property may be present:
```
daptm:onScreen
  : "ON"     # default
  | "OFF"
  | "ON_OFF"
|
"OFF_ON"
```

The Represents property indicates which component of the related media object the Script Event represents.

The Represents property is represented in a DAPT Document by a daptm:represents attribute, whose value MUST be a single < content-descriptor >.

The Represents property is inheritable. If it is absent from an element then its computed value is the computed value of the Represents property on its parent element, or, if it has no parent element, it is the empty string. If it is present on an element then its computed value is the value specified.

Note

Since there is no empty < content-descriptor >, this implies that an empty computed Represents property can never be valid; one way to construct a valid DAPT Document is to specify a Represents property on the DAPT Script so that it is inherited by all descendants that do not have a Represents property.

It is an error for a Represents property value not to be a content descriptor sub-type of at least one of the values in the Script Represents property.

The Script Event Description object is an annotation providing a human-readable description of some aspect of the content of a Script Event . Script Event Descriptions can themselves be classified with a Description Type .

A Script Event Description object is represented in a DAPT Document by a <ttm:desc> element at the <div> element level.

Zero or more <ttm:desc> elements MAY be present.

Script Event Descriptions SHOULD NOT be empty.

Note

The Script Event Description does not need to be unique, i.e. it does not need to have a different value for each Script Event . For example a particular value could be re-used to identify in a human-readable way one or more Script Events that are intended to be processed together, e.g. in a batch recording.

The <ttm:desc> element MAY specify its language using the xml:lang attribute.

Note

In the absence of an


xml:lang

attribute the language of the Script Event Description is inherited from the parent Script Event object.

Example 25

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/event-desc.xml</pre>
</body>

</

html

>

Each Script Event Description can be annotated with one or more Description Types to categorise further the purpose of the Script Event Description.

Each Description Type is represented in a DAPT Document by a daptm:descType attribute on the <ttm:desc> element.

The <ttm:desc> element MAY have zero or one daptm:descType attributes. The daptm:descType attribute is defined below.


daptm:descType
:
string

The permitted values for daptm:descType are either those listed in the following registry table , or can be user-defined:

Registry table for the `daptm:descType` attribute whose Registry Definition is at H.2.1 `daptm:descType` registry table definition
`daptm:descType`	Status	Description	Notes
pronunciationNote	Provisional	Notes for how to pronounce the content.
scene	Provisional	Contains a scene identifier
plotSignificance	Provisional	Defines a measure of how significant the content is to the plot.	Contents are undefined and may be low, medium or high, or a numerical scale.

Valid user-defined values MUST begin with x-.

Example 26

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/event-desc-descType.xml</pre>
</body>

</

html

>

Amongst a sibling group of <ttm:desc> elements there are no constraints on the uniqueness of the daptm:descType attribute, however it may be useful as a distinguisher as shown in the following example.

Example 27

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/event-desc-multiple-descType.xml</pre>
</body>

</

html

>

An Audio object is used to specify an audio rendering of a Text . The audio rendering can either be a recorded audio resource, as an Audio Recording object, or a directive to synthesize a rendering of the text via a text to speech engine, which is a Synthesized Audio object. Both are types of Audio object.

It is an error for an Audio not to be in the same language as its Text .

A presentation processor that supports audio plays or inserts the Audio at the specified time on the related media object 's timeline.

Note

The Audio object is "abstract": it only can exist as one of its sub-types, Audio Recording or Synthesized Audio .

An Audio Recording is an Audio object that references an audio resource. It has the following properties:

One or more alternative Sources , each of which is either 1) a link to an external audio resource or 2) an embedded audio recording;
For each Source , one mandatory Type that specifies the type ([ MIME-TYPES ]) of the audio resource, for example audio/basic ;
An optional Begin property and an optional End and an optional Duration property that together define the Audio Recording 's time interval in the programme timeline, in relation to the parent element's time interval;
An optional In Time and an optional Out Time property that together define a temporal subsection of the audio resource;
The default In Time is the beginning of the audio resource.

The default Out Time is the end of the audio resource.

If the temporal subsection of the audio resource is longer than the duration of the Audio Recording 's time interval, then playback MUST be truncated to end when the Audio Recording 's time interval ends.

Note

"Extended descriptions" (known in [ media-accessibility-reqs ] as "Extended video descriptions") are longer than the allocated time within the related media. A presentation processor that supports extended descriptions can allow the effective play rate of the audio resource to differ from the play rate of the related media object so that the resulting interval has a long enough duration to accommodate the audio resource's temporal subsection. For example it could pause or slow down playback of the related media object while continuing playback of the audio resource, or it could speed up playback of the audio resource, so that the Audio Recording 's time interval does not end before the audio resource's temporal subsection. This behaviour is currently unspecified and therefore implementation-defined.

If the temporal subsection of the audio resource is shorter than the duration of the Audio Recording 's time interval, then the audio resource plays once.
Zero or more Mixing Instructions that modify the playback characteristics of the Audio Recording .

When a list of Sources is provided, a presentation processor MUST play no more than one of the Sources for each Audio Recording .

This feature may contribute to browser fingerprintability. Implementations can use the Type , and if present, any relevant additional formatting information, to decide which Source to play. For example, given two Sources , one being a WAV file, and the other an MP3, an implementation that can play only one of those formats, or is configured to have a preference for one or the other, would select the playable or preferred version.

An Audio Recording is represented in a DAPT Document by an <audio> element child of a <p> or <span> element corresponding to the Text to which it applies. The following constraints apply to the <audio> element:

The begin, end and dur attributes represent respectively the Begin , End and Duration properties;
The clipBegin and clipEnd attributes represent respectively the In Time and Out Time properties, as illustrated by Example 5 ;
For each Source , if it is a link to an external audio resource, the Source and Type properties are represented by exactly one of:
1. A src attribute that is not a fragment identifier, and a type attribute respectively;
  This mechanism cannot be used if there is more than one Source .
  Example 28
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/audio-single-external-source.xml</pre>
</body>

</

html

>
```
2. A <source> child element with a src attribute that is not a fragment identifier and a type attribute respectively;
  Example 29
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/audio-multiple-external-source.xml</pre>
</body>

</

html

>
```
A src attribute that is not a fragment identifier is a URL that references an external audio resource, i.e. one that is not embedded within the DAPT Script . No validation that the resource can be located is specified in DAPT .

Editor's note

Do we need both mechanisms here? It's not clear what semantic advantage the child <source> element carries in this case. Consider marking use of that child <source> element as "at risk"?
Issue 113: Support both `@src` and `<source>` child of `<audio>` (external resources)? question PR-must-have
```
          While working on the specification for adding audio recordings I reminded myself of the various ways in which an audio recording can be embedded and referenced, of which there are at least 5 in total. Requirement R15 of [DAPT](https://www.w3.org/TR/dapt-reqs/#requirements) is clear that both referenced and embedded options need to be available, but should we be syntactically restricting the options for each? Will raise as separate issues.
```
Originally posted by @nigelmegitt in #105 (comment)

The following two options exist in TTML2 for referencing external audio resources:
1. src attribute in <audio> element.
```
<audio
src="https://example.com/audio_recording.wav"
type="audio/wave"/>
```
1. <source> element child of <audio> element.
```
<audio>
    <source src="https://example.com/audio_recording.wav" type="audio/wave"/>
</audio>
```
This second option has an additional possibility of specifying a format attribute in case type is inadequate. It also permits multiple <source> child elements, and we specify that in this case the implementation must choose no more than one.

[Edited 2023-03-29 to account for the "play no more than one" constraint added after the issue was opened]
Issue 218 : At-risk: support for `src` attribute in `<audio>` for external resource PR-must-have

Possible resolution to #113 .

Issue 219 : At-risk: support for `<source>` element child of `<audio>` for external resource PR-must-have

Possible resolution to #113 .
If the Source is an embedded audio resource, the Source and Type properties are represented together by exactly one of:
1. A src attribute that is a fragment identifier that references either an <audio> element or a <data> element, where the referenced element is a child of /tt/head/resources and specifies a type attribute and the xml:id attribute used to reference it;
  This mechanism cannot be used if there is more than one Source .
  Example 30
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/audio-single-embedded-referenced-source.xml</pre>
</body>

</

html

>
```
2. A <source> child element with a src attribute that is a fragment identifier that references either an <audio> element or a <data> element, where the referenced element is a child of /tt/head/resources and specifies a type attribute and the xml:id attribute used to reference it;
  Example 31
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/audio-multiple-embedded-referenced-source.xml</pre>
</body>

</

html

>
```
3. A <source> child element with a <data> element child that specifies a type attribute and contains the audio recording data.
  Example 32
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/audio-single-embedded-inline-source.xml</pre>
</body>

</

html

>
```
In each of the cases above the type attribute represents the Type property.

A src attribute that is a fragment identifier is a pointer to an audio resource that is embedded within the DAPT Script

If <data> elements are defined, each one MUST contain either #PCDATA or <chunk> child elements and MUST NOT contain any <source> child elements.

<data> and <source> elements MAY contain a format attribute whose value implementations MAY use in addition to the type attribute value when selecting an appropriate audio resource.

Editor's note

Do we need all 3 mechanisms here? Do we need any? There may be a use case for embedding audio data, since it makes the single document a portable (though large) entity that can be exchanged and transferred with no concern for missing resources, and no need for e.g. manifest files. If we do not need to support referenced embedded audio then only the last option is needed, and is probably the simplest to implement. One case for referenced embedded audio is that it more easily allows reuse of the same audio in different document locations, though that seems like an unlikely requirement in this use case. Another is that it means that all embedded audio is in an easily located part of the document in tt/head/resources, which potentially could carry an implementation benefit? Consider marking the embedded data features as "at risk"?
Issue 114: Support both `@src` and `<source>` child of `<audio>` (embedded resources)? question PR-must-have
```
          While working on the specification for adding audio recordings I reminded myself of the various ways in which an audio recording can be embedded and referenced, of which there are at least 5 in total. Requirement R15 of [DAPT](https://www.w3.org/TR/dapt-reqs/#requirements) is clear that both referenced and embedded options need to be available, but should we be syntactically restricting the options for each? Will raise as separate issues.
```
Originally posted by @nigelmegitt in #105 (comment)

Given some embedded audio resources:
```
<head>
  <resources>
    <audio xml:id="audioRecording1" type="audio/wave">
      <source>
        <data>[base64 encoded audio data]</data>
      </source>
    </audio>
    <data xml:id="audioRecording2" type="audio/wave">
      [base64 encoded audio data]
    </data>
  </resources>
</head>
```
The following two options exist in TTML2 for referencing embedded audio resources:
1. src attribute in <audio> element referencing embedded <audio> or <data>:
```
<audio src="#audioRecording1"/>
...
<audio src="#audioRecording2"/>
```
1. <source> element child of <audio> element.
```
<audio>
    <source src="#audioRecording1"/>
</audio>
```
This second option has an additional possibility of specifying a format attribute in case type is inadequate. It also permits multiple <source> child elements, though it is unclear what the semantic is intended to be if multiple resources are specified - presumably, the implementation gets to choose one somehow.
Issue 115: Support both referenced and inline embedded audio recordings? question PR-must-have
```
          While working on the specification for adding audio recordings I reminded myself of the various ways in which an audio recording can be embedded and referenced, of which there are at least 5 in total. Requirement R15 of [DAPT](https://www.w3.org/TR/dapt-reqs/#requirements) is clear that both referenced and embedded options need to be available, but should we be syntactically restricting the options for each? Will raise as separate issues.
```
Originally posted by @nigelmegitt in #105 (comment)

If we are going to support embedded audio resources, they can either be defined in /tt/head/resources and then referenced, or the data can be included inline.

Do we need both options?

Example of embedded:
```
<head>
  <resources>
    <audio xml:id="audioRecording1" type="audio/wave">
      <source>
        <data>[base64 encoded audio data]</data>
      </source>
    </audio>
    <data xml:id="audioRecording2" type="audio/wave">
      [base64 encoded audio data]
    </data>
  </resources>
</head>
```
This would then be referenced in the body content using something like (see also #114 ):
```
<audio src="#audioRecording2"/>
```
Example of inline:
```
<audio type="audio/wave">
  <source type="audio/wave">
    <data>[base64 encoded audio data]</data>
  </source>
</audio>
```
Issue 220 : At-risk: support for `src` attribute of `<audio>` element pointing to embedded resource PR-must-have

Possible resolution to #114 and #115 .

The link to #115 is that this implies the existence of some referenceable embedded audio resource too, which one of the options described in #115 .

Issue 221 : At-risk: support for `<source>` child of `<audio>` element pointing to embedded resource PR-must-have

Possible resolution to #114 and #115 .

The link to #115 is that this implies the existence of some referenceable embedded audio resource too, which one of the options described in #115 .

Issue 222 : At-risk: support for inline audio resources PR-must-have

Possible resolution to #115 .

Issue 116 : Add non-inlined embedded audio resources to the Data Model? question PR-must-have

See also #115 - if we are going to support non-inline embedded audio resources, should we make an object for them and add it into the Data Model?
Issue 117 : Embedded data: Do we need to support all the permitted encodings? What about length? question PR-must-have

In TTML2's <data> element, an encoding can be specified, being one of:
- base16
- base32
- base32hex
- base64
- base64url
Do we need to require processor support for all of them, or will the default base64 be adequate?

Also, it is possible to specify a length attribute that provides some feasibility of error checking, since the decoded data must be the specified length in bytes. Is requiring support for this a net benefit? Would it be used?
Issue 223 : At-risk: each of the potential values of `encoding` in `<data>` PR-must-have

Possible resolution to #117 .

Issue 224 : At-risk: support for the `length` attribute on `<data>` PR-must-have

Possible resolution to #117 .
Mixing Instructions MAY be applied as specified in their TTML representation ;
The computed value of the xml:lang attribute MUST be identical to the computed value of the xml:lang attribute of the parent element and any child <source> elements and any referenced embedded <data> elements.

A Synthesized Audio is an Audio object that represents a machine generated audio rendering of the parent Text content. It has the following properties:

A mandatory Rate that specifies the rate of speech, being normal, fast or slow ;
An optional Pitch that allows adjustment of the pitch of the speech.

A Synthesized Audio is represented in a DAPT Document by the application of a tta:speak style attribute on the element representing the Text object to be spoken, where the computed value of the attribute is normal, fast or slow. This attribute also represents the Rate Property.

The tta:pitch style attribute represents the Pitch property.

The TTML representation of a Synthesized Audio is illustrated by Example 6 .

Note

A tta:pitch attribute on an element whose computed value of the tta:rate attribute is none has no effect. Such an element is not considered to have an associated Synthesized Audio .

Note

The semantics of the Synthesized Audio vocabulary of DAPT are derived from equivalent features in [ SSML ] as indicated in [ TTML2 ]. This version of the specification does not specify how other features of [ SSML ] can be either generated from DAPT or embedded into DAPT documents . The option to extend [ SSML ] support in future versions of this specification is deliberately left open.

A Mixing Instruction object is a static or animated adjustment of the audio relating to the containing object. It has the following properties:

Zero or more Gain properties. The gain acts as a multiplier to be applied to the related Audio ;
Zero or more Pan properties. The pan adjusts the stereoscopic (left/right) position;
An optional Begin and an optional End and an optional Duration property that together define the time interval during which the Mixing Instruction applies;
An optional Fill property that specifies whether, at the end time of an animated Mixing Instruction , the specified Gain and Pan properties should be retained ( freeze ) or reverted ( remove ).

A Mixing Instruction is represented by applying audio style attributes to the element that corresponds to the relevant object, either inline, by reference to a <style> element, or in a child (inline) <animate> element:

The tta:gain attribute represents the Gain property;
The tta:pan attribute represents the Pan property.

If the Mixing Instruction is animated, that is, if the adjustment properties change during the containing object's active time interval, then it is represented by one or more child <animate> elements. This representation is required if more than one Gain or Pan property is needed, or if any timing properties are needed.

The <animate> element(s) MUST be children of the element corresponding to the containing object, and have the following constraints:

The begin, end and dur attributes represent respectively the Begin , End and Duration properties;
The fill attribute represents the Fill property;
The tta:gain attribute represents the Gain property, and uses the animation-value-list syntax to express the list of values to be applied during the animation period;
The tta:pan attribute represents the Pan property, and uses the animation-value-list syntax to express the list of values to be applied during the animation period.

The TTML representation of animated Mixing Instructions is illustrated by Example 4 .

See also E. Audio Mixing .

A DAPT Document MUST be serialised as a well-formed XML 1.0 [ xml ] document encoded using the UTF-8 character encoding as specified in [ UNICODE ].

The resulting [ xml ] document MUST NOT contain any of the following physical structures:

entity declarations ; and
entity references other than to predefined entities .

Note

The resulting [ xml ] document can contain character references , and entity references to predefined entities .

The predefined entities are (including the leading ampersand and trailing semicolon):

& for an ampersand & (unicode code point U+0026)
' for an apostrophe ' (unicode code point U+0027)
> for a greater than sign > (unicode code point U+003E)
< for a less than sign < (unicode code point U+003C)
" for a quote symbol " (unicode code point U+0022)

Note

A DAPT Document can also be used as an in-memory model for processing, in which case the serialisation requirements do not apply.

The requirements in this section are intended to facilitate forwards and backwards compatibility, specifically to permit:

DAPT processors targeted at one version of the specification to process DAPT documents that include vocabulary or semantics defined in future versions, albeit without supporting the later features;
DAPT processors targeted at one version of the specification to process DAPT documents authored for an earlier version with similar or identical behaviour to a DAPT processor targeted at that earlier version.

A DAPT document that conforms to more than one version of the specification could specify conformance to multiple DAPT content profiles .

Unrecognised vocabulary is the set of elements and attributes that are not associated with features that the processor supports.

A transformation processor MUST prune unrecognised vocabulary that is neither an attribute nor a descendant of a <metadata> element.

A transformation processor SHOULD preserve unrecognised vocabulary that is either an attribute or a descendant of a <metadata> element.

Note

See also 5.6.2 ttp:contentProfiles which prohibits the signalling of profile conformance to profiles that the transformation processor does not support.

After attribute value computation , a presentation processor SHOULD ignore unrecognised vocabulary .

Note

The above constraint is specified as being after attribute value computation because it is possible that an implementation recognises and supports attributes present only on particular elements, for example those corresponding to the DAPT data model. As described in 6.4 Using computed attribute values it is important that processor implementations do not ignore such attributes when present on other elements.

Foreign vocabulary is the subset of unrecognised vocabulary that consists of those elements and attributes whose namespace is not one of the namespaces listed in 5.3 Namespaces and those attributes whose namespace has no value that are not otherwise defined in DAPT or in [ TTML2 ].

A DAPT Document MAY contain foreign vocabulary that is neither specifically permitted nor forbidden by the profiles signalled in ttp:contentProfiles .

Note

For validation purposes it is good practice to define and use a specification for all foreign vocabulary used within a DAPT Document , for example a content profile .

Many dubbing and audio description workflows permit annotation of Script Events or documents with proprietary metadata. Metadata vocabulary defined in this specification or in [ TTML2 ] MAY be included. Foreign vocabulary MAY also be included, either as attributes of <metadata> elements or as descendant elements of <metadata> elements.

Note

It is possible to add information such as the title of the programme using [ TTML2 ] constructs.

Example 33

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/metadata-ttml2.xml</pre>
</body>

</

html

>

Note

It is possible to add workflow-specific information using a foreign namespace. In the following example, a fictitious namespace vendorm from an "example vendor" is used to provide document-level information not defined by DAPT .

Example 34

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/metadata-proprietary.xml</pre>
</body>

</

html

>

It is strongly recommended not to place data whose semantics depend on the contents of the document within <metadata> elements.

Such data can be invalidated by transformation processors that modify the contents of the document but preserve metadata while being unaware of their semantics.

This section is non-normative.

If foreign vocabulary is included in locations other than <metadata> elements it will be pruned by transformation processors that do not support features associated with that vocabulary, as required in 5.2.1 Unrecognised vocabulary .

A mechanism is provided to prevent such pruning, and to define semantics for such foreign vocabulary , allowing it to be located outside a <metadata> element without being pruned, and to indicate content and processor conformance:

Define a profile including a feature definition for that semantic and vocabulary, with a profile designator.
Signal document conformance to that profile using the 5.6.2 ttp:contentProfiles

This allows processors that support the feature to process the vocabulary in whatever way is appropriate, to avoid pruning it, and allows processors that do not support the feature to take appropriate action, for example warning users that some functionality may be lost.

The following namespaces (see [ xml-names ]) are used in this specification:

Name	Prefix	Value	Defining Specification
XML	`xml`	`http://www.w3.org/XML/1998/namespace`	[ xml-names ]
TT	`tt`	`http://www.w3.org/ns/ttml`	[ TTML2 ]
TT Parameter	`ttp`	`http://www.w3.org/ns/ttml#parameter`	[ TTML2 ]
TT Audio Style	`tta`	`http://www.w3.org/ns/ttml#audio`	[ TTML2 ]
TT Metadata	`ttm`	`http://www.w3.org/ns/ttml#metadata`	[ TTML2 ]
TT Feature	none	`http://www.w3.org/ns/ttml/feature/`	[ TTML2 ]
DAPT Metadata	`daptm`	`http://www.w3.org/ns/ttml/profile/dapt#metadata`	This specification
DAPT Extension	none	`http://www.w3.org/ns/ttml/profile/dapt/extension/`	This specification
EBU-TT Metadata	`ebuttm`	`urn:ebu:tt:metadata`	[ EBU-TT-3390 ]

The namespace prefix values defined above are for convenience and DAPT Documents MAY use any prefix value that conforms to [ xml-names ].

The namespaces defined by this specification are mutable as described in [ namespaceState ]; all undefined names in these namespaces are reserved for future standardization by the W3C .

Within DAPT , the common language terms audio and video are used in the context of a programme. The audio and video are each a part of what is defined in [ TTML2 ] as the Related Media Object that provides the media timeline and is the source of the main programme audio , and any visual timing references needed when adjusting timings relevant to the video image, such as for lip synchronization.

Note

A DAPT document can identify the programme acting as the Related Media Object using metadata. For example, it is possible to use the <ebuttm:sourceMediaIdentifier> element defined in [ EBU-TT-3390 ].

Example 35

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/sourceMediaIdentifier.xml</pre>
</body>

</

html

>

If the DAPT Document is intended to be used as the basis for producing an [ TTML-IMSC1.2 ] document, the synchronization provisions of [ TTML-IMSC1.2 ] apply in relation to the video.

Timed content within the DAPT Document is intended to be rendered starting and ending on specific audio samples.

Note

In the context of this specification rendering could be visual presentation of text, for example to show an actor what words to speak, or could be audible playback of an audio resource, or could be physical or haptic, such as a Braille display.

In constrained applications, such as real-time audio mixing and playback, if accurate synchronization to the audio sample cannot be achieved in the rendered output, the combined effects of authoring and playback inaccuracies in timed changes in presentation SHOULD meet the synchronization requirements of [ EBU-R37 ], i.e. audio changes are not to precede image changes by more than 40ms, and are not to follow them by more than 60ms.

Likewise, authoring applications SHOULD allow authors to meet the requirements of [ EBU-R37 ] by defining times with an accuracy such that changes to audio are less than 15ms after any associated change in the video image, and less than 5ms before any associated change in the video image.

Taken together, the above two constraints on overall presentation and on DAPT documents intended for real-time playback mean that content processors SHOULD complete audio presentation changes no more than 35ms before the time specified in the DAPT document and no more than 45ms after the time specified.

This section defines how a TTML Document Instance signals that it is a DAPT Document and how it signals any processing requirements that apply. See also 7.1 Conformance of DAPT Documents , which defines how to establish that a DAPT Document conforms to this specification.

This profile is associated with the following profile designators:

Profile Name	Profile type	Profile Designator
DAPT 1.0 Content Profile	content profile	`http://www.w3.org/ns/ttml/profile/dapt1.0/content`
DAPT 1.0 Processor Profile	processor profile	`http://www.w3.org/ns/ttml/profile/dapt1.0/processor`

The ttp:contentProfiles attribute is used to declare the [ TTML2 ] profiles to which the document conforms.

DAPT Documents MUST specify a ttp:contentProfiles attribute on the <tt> element including at least one value equal to a content profile designator specified at 5.6.1 Profile Designators . Other values MAY be present to declare conformance to other profiles of [ TTML2 ], and MAY include profile designators in proprietary namespaces.

It is an error for a DAPT Document to signal conformance to a content profile to which it does not conform.

Transformation processors MUST NOT include values within the ttp:contentProfiles attribute associated with profiles that they (the processors) do not support; by definition they cannot verify conformance of the content to those profiles.

The ttp:profile attribute is a mechanism within [ TTML1 ] for declaring the processing requirements for a Document Instance . It has effectively been superceded in [ TTML2 ] by ttp:processorProfiles .

DAPT Documents MUST NOT specify a ttp:profile attribute on the <tt> element.

The ttp:processorProfiles attribute is used to declare the processing requirements for a Document Instance .

DAPT Documents MAY specify a ttp:processorProfiles attribute on the <tt> element. If present, the ttp:processorProfiles attribute MUST include at least one value equal to a processor profile designator specified at 5.6.1 Profile Designators . Other values MAY be present to declare additional processing constraints, and MAY include profile designators in proprietary namespaces.

Note

The ttp:processorProfiles attribute can be used to signal that features and extensions in additional profiles need to be supported to process the Document Instance successfully. For example, a local workflow might introduce particular metadata requirements, and signal that the processor needs to support those by using an additional processor profile designator.

Note

If the content author does not need to signal that additional processor requirements than those defined by DAPT are needed to process the DAPT document then the ttp:processorProfiles attribute is not expected to be present.

[ TTML2 ] specifies a vocabulary and semantics that can be used to define the set of features that a document instance can make use of, or that a processor needs to support, known as a Profile .

Except where specified, it is not a requirement of DAPT that this profile vocabulary is supported by processors; nevertheless such support is permitted.

The majority of this profile vocabulary is used to indicate how a processor can compute the set of features that it needs to support in order to process the Document Instance successfully. The vocabulary is itself defined in terms of TTML2 features. Those profile-related features are listed within F. Profiles as being optional. They MAY be implemented in processors and their associated vocabulary MAY be present in DAPT Documents .

Note

Unless processor support for these features and vocabulary has been arranged (using an out-of-band protocol), the vocabulary is not expected to be present.

The additional profile-related vocabulary for which processor support is not required (but is permitted) in DAPT is:

the <ttp:profile> element;
the <ttp:feature> and <ttp:extension> elements;
the ttp:permitFeatureNarrowing attribute;
the ttp:permitFeatureWidening attribute;
the ttp:contentProfileCombination attribute;
the ttp:inferProcessorProfileSource attribute;
the ttp:processorProfileCombination attribute.

Within a DAPT Script, the following constraints apply in relation to time attributes and time expressions:

The only permitted ttp:timeBase attribute value is media, since F. Profiles prohibits all timeBase features other than #timeBase-media .

This means that the beginning of the document timeline, i.e. time "zero", is the beginning of the Related Media Object .

The only permitted value of the timeContainer attribute is the default value, par.

Documents SHOULD omit the timeContainer attribute on all elements.

Documents MUST NOT set the timeContainer attribute to any value other than par on any element.

Note

This means that the begin attribute value for every timed element is relative to the computed begin time of its parent element, or for the <body> element, to time zero.

If the document contains any time expression that uses the f metric, or any time expression that contains a frames component, the ttp:frameRate attribute MUST be present on the <tt> element.

Note

[ TTML2 ] specifies the


ttp:frameRateMultiplier

attribute for defining non-integer frame rates.

If the document contains any time expression that uses the t metric, the ttp:tickRate attribute MUST be present on the <tt> element.

All time expressions within a document SHOULD use the same syntax, either clock-time or offset-time as defined in [ TTML2 ], with DAPT constraints applied.

Note

A DAPT clock-time has one of the forms:

hh:mm:ss.sss
hh:mm:ss

where hh is hours, mm is minutes, ss is seconds, and ss.sss is seconds with a decimal fraction of seconds (any precision).

Note

Clock time expressions that use frame components, which look similar to "time code", are prohibited due to the semantic confusion that has been observed elsewhere when they are used, particularly with non-integer frame rates, "drop modes" and sub-frame rates.

Note

An offset-time has one of the forms:

nn metric
nn.nn metric

where nn is an integer, nn.nn is a number with a decimal fraction (any precision), and metric is one of:

h for hours,
m for minutes,
s for seconds,
ms for milliseconds,
f for frames, and
t for ticks.

When mapping a media time expression M to a frame F of the video, e.g. for the purpose of accurately timing lip synchronization, the content processor SHOULD map M to the frame F with the presentation time that is the closest to, but not less, than M.

A media time expression of 00:00:05.1 corresponds to frame ceiling( 5.1 × ( 1000 / 1001 × 30) ) = 153 of a video that has a frame rate of 1000 / 1001 × 30 ≈ 29.97.

This specification does not put additional constraints on the layout and rendering features defined in [ TTML-IMSC1.2 ].

Note

Layout of the paragraphs may rely on the default TTML region (i.e. if no


<layout>

element is used in the


<head>

element) or may be explicit by the use of the


region

attribute, to refer to a


<region>

element present at


/tt/head/layout/region

Style references or inline styles MAY be used, using any combination of style attributes, <style> elements and inline style attributes as defined in [TTML2] or [ TTML -IMSC1.2].

The following metadata elements are permitted in DAPT and specified in [ TTML2 ] as containing #PCDATA, i.e. text data only with no element content. Where bidirectional text is required within the character content within such an element, Unicode control characters can be used to define the base direction within arbitrary ranges of text.

<ttm:copyright>
<ttm:desc>
<ttm:item>
<ttm:name>
<ttm:title>

Note

More guidance about usage of this mechanism is available at Inline markup and bidirectional text in HTML .

The <p> and <span> content elements permit the direction of text to be specified using the tts:direction and tts:unicodeBidi attributes. Document authors should use this more robust mechanism rather than using Unicode control characters.

Note

The following example taken from [ TTML2 ] demonstrates the syntax for bidirectional text markup within the <p> and <span> elements.

Example 36

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/bidi-in-p.xml</pre>
</body>

</

html

>

An example rendering of the above fragment is shown below.

4. DAPT Data Model and corresponding TTML syntax defines how objects and properties of the DAPT data model are represented in [ TTML2 ], i.e. in a DAPT Document . However, a DAPT data model instance can be represented by multiple [ TTML2 ] document instances .

For example, 4. DAPT Data Model and corresponding TTML syntax does not mandate that a <div> element representing a Script Event be a direct child of the <body> element. That <div> element could be nested in another <div> element. Therefore, it is possible to serialize the objects and properties of a DAPT Script into various DAPT Documents . This section defines how to interoperably and unambiguously reconstruct a DAPT model instance from a DAPT Document .

Note

DAPT does not define a complete serialization of the DAPT data model for extensibility reasons, to allow future versions to do so if needed. Additionally, a DAPT Document can contain elements or attributes that are not mentioned in the representations of DAPT objects or properties. This could be because it has been generated by a processor conformant to some future version of DAPT , or through a generic [ TTML2 ] process, or because it uses optional features, for example to add styling or layout. This section defines how to process those elements or attributes.

Note

It is also possible to process DAPT Documents using generic [ TTML2 ] processors, which do not necessarily map the documents to the DAPT data model. For example a generic TTML2 presentation processor could render an audio mix based on a DAPT document without needing to model Script Events per se . In that case, this section can be ignored.

This section is non-normative.

Normative provisions relating to this section are defined in [ TTML2 ].

Since it is a requirement of DAPT that DAPT Documents include a ttp:contentProfiles attribute on the root element, and that the attribute includes a DAPT content profile designator, as specified at 5.6.2 ttp:contentProfiles , it follows that any TTML document that does not include such an attribute, or does not include such a profile designator, can be considered not to be a DAPT Document ; therefore a processor requiring strict adherence to DAPT could stop processing such a document.

A processor that takes as its input a DAPT document that contains vocabulary relating to features that it does support, but where support for those features is excluded from the content profiles to which the document claims conformance, SHOULD NOT implement those features in the context of that document.

[ TTML2 ] allows <div> elements to contain any combination of <div> elements and <p> elements. The DAPT data model describes how each Script Event is represented by a <div> element that contains zero or more <p> elements. It also permits other intermediate <div> elements in the path between the <body> element and those Script Event <div> elements. In addition, attributes not corresponding to properties in the DAPT data model are permitted.

This gives rise to possibilities such as:

<div> elements that contain children that are not Text objects, for example other <div> elements or <metadata> elements;
<div> elements that do not have attributes required for Script Events , like xml:id ;
<div> elements that have attributes absent from the DAPT data model for Script Events , like xml:space ;
<p> elements whose parent <div> element does not appear to be a Script Event .

The following processing rules resolve these cases.

Rules for identifying Script Events :

A <div> element that has no <div> element children and includes the TTML representations of all the mandatory properties of a Script Event MUST be mapped to a Script Event , such as having a valid xml:id representing the Script Event Identifier , even if it also contains additional unrecognised vocabulary ;
A <div> element that contains any <div> element children MUST NOT be mapped to a Script Event ; the processor instead MUST iterate through those <div> element children (recursively, in a depth-first traversal) and consider if each one meets the requirements of a Script Event ;
Any remaining unmapped <div> elements MUST NOT be mapped to a Script Event .

Rules for identifying Text objects:

A <p> element that is a child of a <div> element that maps to a Script Event MUST be mapped to a Text object.
A <p> element that is not a child of a <div> element that maps to a Script Event MUST NOT be mapped to a Text object.

Note

Future versions of DAPT could include features that use these structural possibilities differently, and therefore define other processing rules that are mutually exclusive with the rules defined here.

Example 37

This example demonstrates the above possibilities, and the application of the rules:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/non-dapt-divs.xml</pre>
</body>

</

html

>

The result of applying the above rules to this example is:

d1 is a Script Event and its child <p> element is a Text object;
The <div> element between d1 and d2 's parent <div> element is not a Script Event and its child <p> element is not a Text object;
d2 is a Script Event and its parent <div> element is not;
d3 is a Script Event and its parent and its grandparent <div> elements are not;
d4_1 is not a Script Event and its child <p> element is not a Text object;
d4_2 is a Script Event .

Some attributes have semantics for computing their value that depend on the computed value of the attribute on some other element. For example if the xml:lang attribute is not specified on an element then its computed value is the computed value of the same attribute on the element's parent.

Or, for another example, the computed times of an element in a DAPT document are relative to the begin time of the element's parent. If a <div> element specifies a begin attribute, then the computed times of its child <div> elements are relative to that parent <div> element's begin time, and so on down the hierarchy. It is important to include those "intermediate" <div> elements' times in the computation even if the processing target is an instance of the DAPT data model in which they have no direct equivalent; otherwise the Script Event Begin and End times would be wrong.

Considering this situation more generally, it is possible that, within a DAPT document, there can be TTML elements that do not directly correspond to objects in the DAPT data model, and those elements can specify attributes that affect the computation of attribute values that apply to elements that do correspond to objects in the DAPT data model.

The semantics defined by [ TTML2 ] or, for vocabulary defined herein, this specification, take precedence in this scenario. Implementations MUST compute attribute values based on the contents of the document instance before applying those computed values to DAPT data model objects. For example a processor that supports TTML2 styling features would need to implement the TTML2 semantics for inheritance and computing relative values of attributes like tts:fontSize.

Example 38

This example demonstrates these possibilities, which a processor might need to handle:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/examples/non-dapt-div-with-begin-and-lang.xml</pre>
</body>

</

html

>

Here, the <div> elements that correspond to Script Events , which have ids d1 and d2, are otherwise (apart from their identifiers) identical, yet their language and Begin properties have different computed values, due to the attributes specified on the <div> element parent of d2.

If an implementation internally creates DAPT data model objects, such as the Script Events shown in the example above, it is important for interoperability that they use the computed values.

This section is non-normative.

As per 5.2.1 Unrecognised vocabulary , implementers of DAPT processors are encouraged to maintain unrecognised vocabulary within <metadata> elements in DAPT Documents . In practice it is possible that an implementation which both inputs DAPT documents and outputs DAPT documents might modify the input document structure and contents, and while doing so, effectively prune those entities with unrecognised vocabulary from the output document.

Normative provisions relating to this section are defined in [ TTML2 ].

[ TTML2 ] defines a validation processor , a class of implementation whose purpose is to assess a document instance and decide if it is valid or not. Typically this would be used within a processing workflow to check that documents are acceptable for onward usage. A real world example would likely not return simply "good" or "bad", but also output informational, warning and error messages describing unusual, unexpected or problematic contents in the input document.

When implementing a validation processor for a DAPT document , strict [ TTML2 ] validation processing rules can be applied. Doing this involves checking for the presence and semantic validity of syntax and content associated with required or optional features defined in the profile, and checking for the absence of syntax associated with prohibited features.

The [ TTML2 ] mechanism for dealing with vocabulary in unrecognised namespaces is to prune it prior to validation. This approach can be used; additionally it could be reasonable for an implementation to report as information those attributes and elements that have been pruned.

Note

The term "vocabulary" here refers to XML elements and attributes.

Validation warnings could be issued when unsupported or deprecated vocabulary in recognised namespaces is encountered after pruning, or when supported vocabulary contains unexpected but not invalid content, but in these scenarios errors are not expected.

Validation errors are expected when prohibited vocabulary is present, or when semantically invalid content within permitted vocabulary is encountered.

This section defines a [ TTML2 ] content profile and a processor profile by expressing dispositions against a set of features and extensions . The DAPT extensions are defined in G. Extensions .

The Profile Semantics specified in [ TTML2 ] apply.

A TTML Profile specification is a document that lists all the features of TTML that are required / optional / prohibited within “document instances” (files) and “processors” (things that process the files), and any extensions or constraints.

A timed text content document instance that conforms to the content profile defined herein:

MUST satisfy all normative provisions specified by the profile;
MAY include any vocabulary, syntax or attribute value associated with a feature or extension whose disposition is permitted or optional in the profile;
MUST include any vocabulary, syntax or attribute value associated with a feature or extension whose disposition is required in the profile.
MUST NOT include any vocabulary, syntax or attribute value associated with a feature or extension whose disposition is prohibited in the profile.

Note

A timed text content document instance , by definition, satisfies the requirements of Section 3.1 at [ TTML2 ], and hence a timed text content document instance that conforms to a profile defined herein is also a conforming TTML2 Document Instance .

A Presentation processor that conforms to the processor profile defined in this specification:

MUST satisfy the Generic Processor Conformance requirements at Section 3.2.1 of [ TTML2 ]
MUST satisfy all normative provisions specified by the profile; and
MUST implement presentation semantic support for every feature or extension designated as permitted or required by the profile, subject to any additional constraints on each feature as specified by the profile.
MAY implement presentation semantic support for every feature or extension designated as optional or prohibited by the profile, subject to any additional constraints on each feature as specified by the profile.

A Transformation processor that conforms to the processor profile defined in this specification:

MUST satisfy the Generic Processor Conformance requirements at Section 3.2.1 of [ TTML2 ];
MUST satisfy all normative provisions specified by the profile; and
MUST implement transformation semantic support for every feature or extension designated as permitted or required by the profile, subject to any additional constraints on each feature as specified by the profile.
MAY implement transformation semantic support for every feature or extension designated as optional or prohibited by the profile, subject to any additional constraints on each feature as specified by the profile.

The dispositions required, permitted, optional and prohibited as used in this specification map to the [ TTML2 ] <ttp:feature> and <ttp:extension> elements' value attribute values as follows:

DAPT disposition	`<ttp:feature>` or `<ttp:extension>` element `value` attribute value in
DAPT disposition	content profile	processor profile
required	required	required
permitted	optional	required
optional	optional	optional
prohibited	prohibited	optional

Note

The use of the terms presentation processor and transformation processor within this document does not imply conformance per se to any of the Standard Profiles defined in [ TTML2 ]. In other words, it is not considered an error for a presentation processor or transformation processor to conform to the profile defined in this document without also conforming to the TTML2 Presentation Profile or the TTML2 Transformation Profile.

Note

The use of the [ TTML2 ] profiling sub-system to describe DAPT conformance within this specification is not intended imply that DAPT processors are required to support any features of that system other than those for which support is explicitly required by DAPT .

Note

This document does not specify presentation processor or transformation processor behavior when processing or transforming a non-conformant timed text content document instance .

Note

The permitted and prohibited dispositions do not refer to the specification of a <ttp:feature> or <ttp:extension> element as being permitted or prohibited within a <ttp:profile> element.

The features and extensions listed in this section express the minimal requirements for DAPT Documents , Presentation Processors , and Transformation Processors . DAPT Documents MAY additionally conform to other profiles, and include syntax not prohibited by the DAPT content profile . Presentation Processors and Transformation Processors MAY support additional syntax and semantics relating to other profiles.

Note

For example, a DAPT Script can include syntax permitted by the IMSC ([ TTML-IMSC1.2 ]) profiles of [ TTML2 ] to enhance the presentation of scripts to actors recording audio, or to add styling important for later usage in subtitle or caption creation.

Editor's note

Editorial task: go through this list of features and check the disposition of each. There should be no prohibited features that are permitted in IMSC.

Feature or Extension	Disposition	Additional provision
Relative to the TT Feature namespace
`#animate-fill`	permitted
`#animate-minimal`	permitted
`#animation-out-of-line`	prohibited	See 4.10 Mixing Instruction .
`#audio`	permitted
`#audio-description`	permitted
`#audio-speech`	permitted
`#bidi`	permitted
`#bidi-version-2`	permitted
`#chunk`	permitted
`#clockMode`	prohibited
`#clockMode-gps`	prohibited
`#clockMode-local`	prohibited
`#clockMode-utc`	prohibited
`#content`	permitted
`#contentProfiles`	permitted	See 5.6.2 `ttp:contentProfiles` and G.3 #contentProfiles-root .
`#contentProfiles-combined`	optional	See 5.6.5 Other TTML2 Profile Vocabulary .
`#core`	permitted
`#data`	permitted
`#direction`	permitted
`#dropMode`	prohibited
`#dropMode-dropNTSC`	prohibited
`#dropMode-dropPAL`	prohibited
`#dropMode-nonDrop`	prohibited
`#embedded-audio`	permitted
`#embedded-data`	permitted
`#frameRate`	permitted	See 5.7.3 `ttp:frameRate` .
`#frameRateMultiplier`	permitted
`#gain`	permitted
`#markerMode`	prohibited
`#markerMode-continuous`	prohibited
`#markerMode-discontinuous`	prohibited
`#metadata`	permitted
`#metadata-item`	permitted
`#metadata-version-2`	permitted
`#pan`	permitted
`#permitFeatureNarrowing`	optional	See 5.6.5 Other TTML2 Profile Vocabulary .
`#permitFeatureWidening`	optional	See 5.6.5 Other TTML2 Profile Vocabulary .
`#pitch`	permitted
`#presentation-audio`	permitted
`#processorProfiles`	optional	See 5.6.4 `ttp:processorProfiles` .
`#processorProfiles-combined`	optional	See 5.6.5 Other TTML2 Profile Vocabulary .
`#profile`	partially permitted	See 5.6.3 `ttp:profile` .
`#profile-full-version-2`	partially permitted	See 5.6.5 Other TTML2 Profile Vocabulary .
`#profile-version-2`	partially permitted	See 5.6.5 Other TTML2 Profile Vocabulary .
`#resources`	permitted
`#set`	permitted
`#set-fill`	permitted
`#set-multiple-styles`	permitted
`#source`	permitted
`#speak`	permitted
`#speech`	permitted
`#structure`	required
`#styling`	permitted
`#styling-chained`	permitted
`#styling-inheritance-content`	permitted
`#styling-inline`	permitted
`#styling-referential`	permitted
`#subFrameRate`	prohibited
`#tickRate`	permitted	See 5.7.4 `ttp:tickRate` .
`#time-clock`	permitted
`#time-clock-with-frames`	prohibited
`#time-offset-with-frames`	permitted	See 5.7.3 `ttp:frameRate` .
`#time-offset-with-ticks`	permitted	See 5.7.4 `ttp:tickRate` .
`#time-offset`	permitted
`#time-wall-clock`	prohibited
`#timeBase-clock`	prohibited
`#timeBase-media`	required	See 5.7.1 `ttp:timeBase` . NOTE: [ TTML1 ] specifies that the default timebase is `"media"` if the `ttp:timeBase` attribute is not specified on the `<tt>` element.
`#timeBase-smpte`	prohibited
`#timeContainer`	prohibited	See 5.7.2 `timeContainer` .
`#timing`	permitted	See 5.7.5 Time expressions .
`#transformation`	permitted	See constraints at #profile .
`#unicodeBidi`	permitted
`#unicodeBidi-isolate`	permitted
`#unicodeBidi-version-2`	permitted
`#xlink`	permitted
Relative to the DAPT Extension namespace
`#agent`	permitted	This is the profile expression of 4.2 Character .
`#contentProfiles-root`	required	This is the profile expression of 5.6.2 `ttp:contentProfiles` .
`#daptOriginTimecode`	permitted	This is the profile expression of D.1 DAPT Origin Timecode .
`#descType`	permitted	This is the profile expression of `daptm:descType` .
`#onScreen`	permitted	This is the profile expression of 4.6 On Screen .
`#profile-root`	prohibited	This is the profile expression of the prohibition of the `ttp:profile` attribute on the `<tt>` element as specified in 5.6.3 `ttp:profile` .
`#represents`	required	This is the profile expression of Represents as applied to Script Event .
`#scriptEventGrouping`	permitted	This is the profile expression of the permission to nest `<div>` elements described in 4.3 Script Event .
`#scriptEventMapping`	optional	This is the profile expression of 6.3 Handling `<div>` and `<p>` elements .
`#scriptRepresents`	required	This is the profile expression of Script Represents .
`#scriptType-root`	required	This is the profile expression of 4.1.3 Script Type .
`#serialization`	required	This is the profile expression of 5.1 Document Encoding .
`#source-data`	prohibited	This is the profile expression of the prohibition of `<source>` child elements of `<data>` elements as specified in 4.9.1 Audio Recording .
`#textLanguageSource`	permitted	This is the profile expression of 4.5 Text Language Source as required at 4.4 Text .
`#xmlId-div`	required	This is the profile expression of 4.3 Script Event .
`#xmlLang-audio-nonMatching`	prohibited	This is the profile expression of the prohibition of the `xml:lang` attribute on the `<audio>` element having a different computed value to the parent element and descendant or referenced `<source>` and `<data>` elements, as specified in 4.9.1 Audio Recording .
`#xmlLang-root`	required	This is the profile expression of 4.1.2 Default Language .

The DAPT Content Profile expresses the conformance requirements of DAPT Scripts using the profile mechanism of [ TTML2 ]. It can be used by a validating processor that supports the DAPT Processor Profile to validate a DAPT Document .

There is no requirement to include the DAPT Content Profile within a DAPT Document .

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/profiles/dapt-content-profile.xml</pre>
</body>

</

html

>

The DAPT Processor Profile expresses the processing requirements of DAPT Scripts using the profile mechanism of [ TTML2 ]. A processor that supports the required features and extensions of the DAPT Processor Profile can, minimally, process all permitted features within a DAPT Document .

There is no requirement to include the DAPT Processor Profile within a DAPT Document .

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /uploads/HLKPCi/profiles/dapt-processor-profile.xml</pre>
</body>

</

html

>

The following sections define extension designations, expressed as relative URIs (fragment identifiers) relative to the DAPT Extension Namespace base URI. These extension designations are used in F. Profiles to describe the normative provisions of DAPT that are not expressed by [ TTML2 ] profile features.

A transformation processor supports the #agent extension if it recognizes and is capable of transforming values of the following elements and attributes on the <ttm:agent> element:

xml:id attribute
<ttm:name> element

and if it recognizes and is capable of transforming each of the following value combinations:

<ttm:agent> element with type="person" and child <ttm:name> element with type="full" ;
<ttm:agent> element with type="character" and child <ttm:name> element with type="alias" ;

A presentation processor supports the #agent extension if it implements presentation semantic support of the above listed elements, attributes and value combinations.

A transformation processor supports the #contentProfiles-root extension if it recognizes and is capable of transforming values of the ttp:contentProfiles attribute on the <tt> element.

A presentation processor supports the #contentProfiles-root extension if it implements presentation semantic support of the ttp:contentProfiles attribute on the <tt> element.

Note

This extension is defined as a subset of




#contentProfiles

to avoid requiring processor support for the



ttp:profile

attribute and processor profile inference semantics.

A transformation processor supports the #daptOriginTimecode extension if it recognizes and is capable of transforming values of the < daptm:daptOriginTimecode > element.

No presentation processor behaviour is defined for the #daptOriginTimecode extension.

A transformation processor supports the #descType extension if it recognizes and is capable of transforming values of the daptm:descType attribute on the <ttm:desc> element.

A presentation processor supports the #descType extension if it implements presentation semantic support of the daptm:descType attribute on the <ttm:desc> element.

A transformation processor supports the #onScreen extension if it recognizes and is capable of transforming values of the daptm:onScreen attribute on the <div> element.

A presentation processor supports the #onScreen extension if it implements presentation semantic support of the daptm:onScreen attribute on the <div> element.

A transformation processor supports the #profile-root extension if it recognizes and is capable of transforming values of the ttp:profile attribute on the <tt> element.

A presentation processor supports the #profile-root extension if it implements presentation semantic support of the ttp:profile attribute on the <tt> element.

A transformation processor supports the #represents extension if it recognizes and is capable of transforming values of the daptm:represents attribute.

A presentation processor supports the #represents extension if it implements presentation semantic support of the daptm:represents attribute.

An example of a transformation processor that supports this extension is a validating processor that reports an error if the extension is permitted by a content profile but the timed text content document instance claiming conformance to that profile has a <div> element with a daptm:represents attribute whose value is not conformant with the requirements defined herein.

A transformation processor supports the #scriptEventGrouping extension if it recognises and is capable of transforming <div> elements that contain <div> elements.

Note

Support for the #scriptEventGrouping extension does not imply support for the #scriptEventMapping extension.

A presentation processor supports the #scriptEventGrouping extension if it implements presentation semantic support for <div> elements that contain <div> elements.

A transformation processor supports the #scriptEventMapping extension if, when mapping a DAPT document into an internal representation of the DAPT data model, it implements the processing requirements specified at 6.3 Handling <div> and <p> elements .

Note

No support for the #scriptEventMapping extension is required for presentation processors because there are no presentation semantics that either require, or depend upon, mapping a DAPT document into an internal representation of the DAPT data model. A presentation processor that does perform such a mapping can also be considered to be a transformation processor for the purpose of this extension.

A transformation processor supports the #scriptRepresents extension if it recognizes and is capable of transforming values of the daptm:scriptRepresents attribute on the <tt> element.

A presentation processor supports the #scriptRepresents extension if it implements presentation semantic support of the daptm:scriptRepresents attribute on the <tt> element.

An example of a transformation processor that supports this extension is a validating processor that reports an error if the extension is required by a content profile but the timed text content document instance claiming conformance to that profile either does not have a daptm:scriptRepresents attribute on the <tt> element or has one whose value is not conformant with the requirements defined herein.

A transformation processor supports the #scriptType-root extension if it recognizes and is capable of transforming values of the daptm:scriptType attribute on the <tt> element.

A presentation processor supports the #scriptType-root extension if it implements presentation semantic support of the daptm:scriptType attribute on the <tt> element.

An example of a transformation processor that supports this extension is a validating processor that provides appropriate feedback, for example warnings, when the SHOULD requirements defined in 4.1.3 Script Type for a DAPT Document 's daptm:scriptType are not met, and that reports an error if the extension is required by a content profile but the timed text content document instance claiming conformance to that profile either does not have a daptm:scriptType attribute on the <tt> element or has one whose value is not defined herein.

A serialized document that is valid with respect to the #serialization extension is an XML 1.0 [ xml ] document encoded using UTF-8 character encoding as specified in [ UNICODE ], that contains no entity declarations and no entity references other than to predefined entities.

A transformation processor or a presentation processor supports the #serialization extension if it can read a serialized document as defined above.

A transformation processor that writes documents supports the #serialization extension if it can write a serialized document as defined above.

A transformation processor supports the #source-data extension if it recognizes and is capable of transforming values of the <source> element child of a <data> element.

A presentation processor supports the #source-data extension if it implements presentation semantic support of the <source> element child of a <data> element.

A transformation processor supports the #textLanguageSource extension if it recognizes and is capable of transforming values of the daptm:langSrc attribute.

A presentation processor supports the #textLanguageSource extension if it implements presentation semantic support of the daptm:langSrc attribute.

A transformation processor supports the #xmlId-div extension if it recognizes and is capable of transforming values of the xml:id attribute on the <div> element.

A presentation processor supports the #xmlId-div extension if it implements presentation semantic support of the xml:id attribute on the <div> element.

A transformation processor supports the #xmlLang-audio-nonMatching extension if it recognizes and is capable of transforming values of the xml:lang attribute on the <audio> element that differ from the computed value of the same attribute of its parent element or any of its descendant or referenced <source> or <data> elements, known as non-matching values.

A presentation processor supports the #xmlLang-audio-nonMatching extension if it implements presentation semantic support of such non-matching xml:lang attribute values.

A transformation processor supports the #xmlLang-root extension if it recognizes and is capable of transforming values of the xml:lang attribute on the <tt> element and the additional semantics specified in 4.1.2 Default Language .

A presentation processor supports the #xmlLang-root extension if it implements presentation semantic support of the xml:lang attribute on the <tt> element and the additional semantics specified in 4.1.2 Default Language .

Dubbing and Audio description Profiles of TTML2

Abstract

Status of This Document

1. Scope

2. Introduction

2.1 Transcripts and Scripts

2.1.1 Dubbing scripts

2.1.2 Audio Description scripts

2.1.3 Other uses

2.2 Example documents

2.2.1 Basic document structure

2.2.2 Audio Description Examples

2.2.3 Dubbing Examples

3. Documentation Conventions

4. DAPT Data Model and corresponding TTML syntax

4.1 DAPT Script

4.1.1 Script Represents

4.1.2 Default Language

4.1.3 Script Type

4.1.4 Script Events

4.1.5 Characters

4.1.6 Shared properties and Value Sets

4.1.6.1 Timing Properties

4.1.6.2 <content-descriptor> values

4.1.6.3 Unique identifiers

4.2 Character

4.3 Script Event

4.4 Text

4.5 Text Language Source

4.6 On Screen

4.7 Represents

4.8 Script Event Description

4.9 Audio

4.9.1 Audio Recording

4.9.2 Synthesized Audio

4.10 Mixing Instruction

5. Constraints

5.1 Document Encoding

5.2 Processing of unrecognised or foreign elements and attributes

5.2.1 Unrecognised vocabulary

5.2.2 Special considerations for foreign vocabulary

5.2.3 Proprietary Metadata and Foreign Vocabulary

5.2.3.1 Defining and using foreign vocabulary that is not metadata

5.3 Namespaces

5.4 Related Media Object

5.5 Synchronization

5.6 Profile Signaling

5.6.1 Profile Designators

5.6.2 ttp:contentProfiles

5.6.3 ttp:profile

5.6.4 ttp:processorProfiles

5.6.5 Other TTML2 Profile Vocabulary

5.7 Timing constraints

5.7.1 ttp:timeBase

5.7.2 timeContainer

5.7.3 ttp:frameRate

5.7.4 ttp:tickRate

5.7.5 Time expressions

5.8 Layout and styles

5.9 Bidirectional text

6. Mapping from TTML to the DAPT Data Model

6.1 Early identification of non-conformant documents

6.2 Not supporting features excluded by the content profile

6.3 Handling <div> and <p> elements

6.4 Using computed attribute values

6.5 Considerations for transformation and validation processors

6.5.1 Retaining unrecognised vocabulary

6.5.2 Validation warnings and errors

7. Conformance

7.1 Conformance of DAPT Documents

7.2 Conformance of DAPT Processors

A. Index

A.1 Terms defined by this specification

A.2 Terms defined by reference

B. Privacy Considerations

B.1 Personal Information

B.2 Audio format preference

C. Security Considerations

D. Timecode-related metadata

D.1 DAPT Origin Timecode

4.1.6.2 `<content-descriptor>` values

5.6.2 `ttp:contentProfiles`

5.6.3 `ttp:profile`

5.6.4 `ttp:processorProfiles`

5.7.1 `ttp:timeBase`

5.7.2 `timeContainer`

5.7.3 `ttp:frameRate`

5.7.4 `ttp:tickRate`

6.3 Handling `<div>` and `<p>` elements

H.2.1 `daptm:descType` registry table definition

H.2.2 `<content-descriptor>` registry table definition