TTML2：下一代字幕标准，ATSC3.0必备

ATSC3.0

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2017/11/23 Timed Text Markup Language 2 (TTML2)

https://www.w3.org/TR/ttml2/ 16/358

Example Fragment

–

TTML Styling

<style xml:id="s1"

tts:color="white"

tts:fontFamily="proportionalSansSerif"

tts:fontSize="22px"

tts:textAlign="center"

</styling>

Layout information defines one or more regions into which content is intended to be presented. A

region definition may reference one or more sets of style specifications in order to permit content

flowed in the region to inherit from these styles. In

Example Fragment

–

TTML Layout

, the region

definition makes reference to style specification s1 augmented by specific inline styles which,

together, allow content flowed into the region to inherit from the region's styles (in the case that

a style is not already explicitly specified on content or inherited via the content hierarchy.)

Example Fragment

–

TTML Layout

<region xml:id="subtitleArea"

style="s1"

tts:extent="560px 62px"

tts:padding="5px 3px"

tts:backgroundColor="black"

tts:displayAlign="after"

</layout>

The content of a document instance is expressed in its body, which is organized in terms of block

and inline text elements. The hierarchical organization of content elements serves a primary role in

determining both spatial and temporal relationships. For example, in

Example Fragment

–

TTML Body

each paragraph (p element) is flowed into its target region in the specified lexical order;

furthermore, the active time interval of each paragraph is timed in accordance to its parent or

sibling according to the applicable time containment semantics — in this case, the division parent

is interpreted (by default) as a parallel time container.

2017/11/23 Timed Text Markup Language 2 (TTML2)

https://www.w3.org/TR/ttml2/ 17/358

Example Fragment

–

TTML Body

<div>

It seems a paradox, does it not,

</p>

that the image formed on<br/>

the Retina should be inverted?

</p>

It is puzzling, why is it<br/>

we do not see things upside-down?

</p>

You have never heard the Theory,<br/>

then, that the Brain also is inverted?

</p>

No indeed! What a beautiful fact!

</p>

But how is it proved?

</p>

Thus: what we call

</p>

the vertex of the Brain<br/>

is really its base

</p>

and what we call its base<br/>

is really its vertex,

</p>

it is simply a question of nomenclature.

</p>

How truly delightful!

</p>

</div>

</body>

The first subtitle

Subtitle 1

–

Time Interval [0.76, 3.45)

is presented during the time interval

0.76 to 3.45 seconds. This subtitle inherits its font family, font size, foreground color, and text

alignment from the region into which it is presented. Since no region is explicitly specified on the

paragraph, the nearest ancestor that specifies a region determines the targeted region. Note also

that content is presented at the bottom (after edge) of the containing region due to the

tts:displayAlign="after" being specified on the region definition.

Note:

The notation "[

]" denotes a closed interval from

, including

and

; "[

denotes a right half-open interval from

, including

but not including

; "(

denotes a left half-open interval from

, not including

but including

; "(

denotes an open interval from

, not including

2017/11/23 Timed Text Markup Language 2 (TTML2)
https://www.w3.org/TR/ttml2/ 20/358
TTML
Timed Text Markup Language
TTAF
Timed Text Authoring Format
TTWG
Timed Text Working Group
2.2 Terminology
[absolute dimension]
A scalar value that denotes a length on either the horizontal axis or the vertical axis.
[abstract document instance]
An instance of an abstract data set as represented by a reduced xml infoset.
[abstract document type]
A set of constraints that defines a class of 
XML Information Sets
 [XML InfoSet].
[anonymous profile]
See undesignated profile.
[attribute information item]
Each specified or defaulted attribute of an XML document corresponds with an attribute
information item as defined by [XML InfoSet], §2.3.
[audio defining context]
The context in which an audio element is specified to serve as a sharable definition to be
referenced by another audio element in an audio presentation context.
[audio generating element]
An audio element in an audio presentation context or a span element whose character content is
used to generate a speech data resource.
[audio presentation context]
The context in which an audio element is specified for the purpose of being presented
(rendered). Such an audio element may specify the audio data inline by using a data element
within a source element child, or it may reference another audio element specified in a audio
defining context, or it may do both.
[audio resource]
A data resource that contains coded or unencoded audio samples.
[audio stream]
A sequence of audio samples.
[background painting rectangle]
A rectangle in the document coordinate space with respect to which a background presentation
artifact, e.g., color or image, is (possibly) clipped and painted; more specifically, one of
three rectangles: the border rectangle, the padding rectangle, or the content rectangle of an
area generated by an element associated with a background. The computed value of the style
property specified by the tts:backgroundClip attribute determines which rectangle applies.
[background positioning rectangle]
A rectangle in the document coordinate space with respect to which a background presentation
artifact, e.g., color or image, is positioned or sized; more specifically, one of three
rectangles: the border rectangle, the padding rectangle, or the content rectangle of an area
generated by an element associated with a background. The computed value of the style property
specified by the tts:backgroundOrigin attribute determines which rectangle applies.
[baseline profile]