Simple Delivery Profile for Closed Captions

Abstract

TTML 1.0 provides many features to satisfy captioning and subtitling requirements, not all of which are intended for end user display. Requirements have been identified by key video and content communities to define an interoperable delivery profile using the core features specifically designed for online presentation of TTML. Such a profile allows the community of TTML users to construct constrained presentation engines for TTML. This document defines the behavior expected of a presentation processor using the player constraints for such an online delivery profile.

The Simple Delivery Profile for Closed Captions focuses interoperability using TTML 1.0 to support delivery of closed captions for video content. Other profiles based on TTML 1.0 may target other types of subtitles such as on-screen text or graphics. This interoperability profile is a proper subset of TTML 1.0 plus features required to support US Government closed captioning requirements for online presentation.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This document is a draft member contribution.

This document applies 3 guiding principles for online delivery of closed captions.

Promote interoperability.
Provide mandatory functionality based on a specified set of TTML features.
Use this functionality to apply constraints on usage of a specified set of TTML features.

This document was published by the Timed Text Working Group as a Note. If you wish to make comments regarding this document, please send them to public-tt@w3.org (subscribe, archives). All feedback is welcome.

Publication as a Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3CPatent Policy. W3Cmaintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3CPatent Policy.

1. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words must, must not, required, should, should not, recommended, may, and optional in this specification are to be interpreted as described in [RFC2119].

Simple Delivery Profile for Closed Captions

This profile identifies the content and player constraints for closed captioning using TTML. To conform to this profile, a presentation engine must:

Satisfy the requirements specified by Section 3.2.1 Generic Processor Conformance [TTML] that are required to implement:

The mandatory TTML 1.0 features referenced in Table E-3, Section D.2 Feature Support
Supports the semantics defined for those features in the context of this profile.

Satisfy all requirements specified in Sections 4-8 and any references from those sections in this document.

This constrained profile enumerates a set of required TTML features, some of which may be constrained in behavior, and the capabilities required of a Presentation Processor in TTML 1.0. The semantics defined in TTML 1.0 apply unless otherwise constrained in this profile. Claims of conformance must use this URI and implement the required features and constraints of use and processing outlined in this profile.

Name	Designator
simple-delivery	http://www.w3.org/TR/profile/simple-delivery

Conformance to this profile does not preclude the use of other features defined in TTML 1.0 but such behavior is not defined here.

2. Terms and Definitions

The terms and definitions in TTML 1.0 serve as the basis for this interoperability profile. Terms found here are in addition to those found in TTML 1.0.

Name	Definition
Required feature	A TTML feature is required for use.
Required feature with constraints	A TTML feature is required but constrained by this profile for use and/or processing.
Optional feature	Any TTML feature not included in this profile.

3. Simple Delivery Profile for Closed Captions

This profile represents a minimum set of required functionality using specified TTML features to deliver closed captions for online-delivery. This profile does not preclude optional features from use.

The functionality is described in how it constrains the use of TTML features and how a processor provides those captions. An example implementing this constrained profile exists in Profile designator; error handling behavior is found in Error Handling.

3.1 Use of TTML Constrained Feature Template

This profile identifies functionality in the context of the required TTML 1.0 features used and applies constraints. Each function is defined by:

Usage scenario
Constraints

The template is as follows:

Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint

Usage Constraints

4. Structural Constraints

Processors must support the capability to present documents where the following constraints apply:

A document must contain both a head and body element

A document must contain both a styling and a layout element.

A document must not use a div element inside a div element.

A document must contain only a single level of span element within a p element

<span style="s1">A</span>
<span style="s3">B</span>
<span style="s1">C</span>

A document must reference all styles using a style attribute to a style element.

A document must have all elements are in order of time. That is, in a par context, no element shall lexically precede another element with an earlier start time.

5. Constrained Features

5.1 Use of Constrained TTML Feature core

5.1.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#core	required

5.1.2 Constraints

None

5.2 Use of Constrained TTML Feature content

5.2.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#content	Required with constraint	Specified elements are used.

5.2.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

A document must contain only the following elements:

tt
head
body
div
p
span
br
set
layout
styling
region
style

5.3 Use of Constrained TTML Feature presentation

5.3.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#presentation	required

5.3.2 Constraints

None

5.4 Use of Constrained TTML Feature profile

5.4.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#profile	required

5.4.2 Constraints

Processors must support the capability to present documents referencing this profile using the following URI: http://www.w3.org/TR/profile/simple-delivery

NOTE: See also Conformance

NOTE: The use attribute could indicate the geographical region for which the profile is used. For example, specific styling capabilities could be used in a particular geographical region. See also Other Constraints.

5.5 Use of Constrained TTML Feature structure

5.5.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#structure	required

5.5.2 Constraints

None

6. Style Constraints

6.1 Use of Constrained TTML Feature backgroundColor-*

6.1.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#backgroundColor-block #backgroundColor-inline	Required with constraints	p element region element

6.1.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

The backgroundColor must be expressed in #rrggbbaa format exclusively using the <hexdigit> style value expression.

The backgroundColor must support the colors outlined in Color Values.

Note: These colors are identical to those identified in the CEA708-D, Section 8.8 [RBG resolution of 4 bits for each primary (03)].

The alpha component of backgroundColor must support the opacity values outlined in Color Values .

The alpha component of backgroundColor for a region must be 00.

The player must allow the user to specify a backgroundColor for p and span elements based on a minimum of an 8-color palette of white, black, red, green, blue, yellow, magenta, and cyan (See Minimum Color List in Color Values ).

The player must allow the user to specify a backgroundColor for p and span elements to allow for semi-transparent and transparent opacities.

6.2 Use of Constrained TTML Feature color

6.2.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#color	Required with constraints

6.2.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

The color must be expressed in #rrggbbaa format exclusively using the <hexdigit> style value expression.

The color must support the colors outlined in Color Values.

Note: These colors are identical to those identified in the CEA708-D, Section 8.8 [RBG resolution of 4 bits for each primary (03)].

The alpha component of color must support the opacity values outlined in Color Values .

The player must allow the user to specify a color for p and span elements based on a minimum of an 8-color palette of white, black, red, green, blue, yellow, magenta, and cyan (See Minimum Color List in Color Values ).

The player must allow the user to specify a color for p and span elements to allow for semi-transparent and transparent opacities.

6.3 Use of Constrained TTML Feature display-region

6.3.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#display-region	required

6.3.2 Constraints

None

6.4 Use of Constrained TTML Feature display-region

6.4.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#display-region	Required with constraints	region root

6.4.2 Constraints

Processors must support the capability to present documents in the following common forms:

Pop-up
Roll-up
Paint-on

Examples are provided of each style to aid in understanding the common forms.

Pop-up style

<tt xml:lang="en-us" xmlns="http://www.w3.org/ns/ttml" 
    xmlns:s='http://www.w3.org/ns/ttml#styling' 
    xmlns:p='http://www.w3.org/ns/ttml#parameter' >
  <head>
    <p:profile use="http://www.w3.org/ns/ttml/profile/online-delivery"/>
    <styling>
      <!-- A typical transparent region with centered text that has an outline -->
      <style xml:id="bottomMidStyle" s:textAlign="center" s:textOutline="#000000ff 5%" s:backgroundColor="#00000000" s:color="#ffffffff" s:origin='20% 58%' s:extent='60% 18%'/>
    </styling>
    <layout>
      <!-- typical 'pop on' type region -->
      <region xml:id="bottomMid" style="bottomMidStyle" />
    </layout>
  </head>
  <body>
    <div style="defaultFont">
      <p region="bottomMid" begin='00:00:00.101' end='00:00:03.000'> This is a pop on caption. </p>
    </div>
  </body>
</tt>

Positioned style. An off-screen narrator is present and no graphics are used. Content placed in a single region in the bottom one-third of that region.

<style xml:id="bottomMidStyle" s:textAlign="center" s:textOutline="black 1px" s:backgroundColor="transparent" s:color="white" s:origin='20% 58%' s:extent='60% 18%'/>
<style xml:id="topMidStyle" s:textAlign="center" s:textOutline="black 1px" s:backgroundColor="transparent" s:color="white" s:origin='20% 10%' s:extent='60% 18%'/>

Moving regions. Content is positioned based on location of speaker, visible in the bottom two lines individually positioned in region(s) so as to avoid background content..

<?xml version="1.0" encoding="utf-8"?>
<tt xml:lang="en-us" xmlns="http://www.w3.org/ns/ttml" xmlns:s='http://www.w3.org/ns/ttml#styling'>
  <head>
    <styling>
      <style xml:id="s1" s:display="none" s:extent='40% 18%'/>
    </styling>
    <layout>
      <region xml:id="r1" style="s1">
        <set begin='00:00:10.000' end='00:00:12.000' s:display='auto'/>
        <set begin='00:00:10.000' end='00:00:12.000' s:origin='10% 10%'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:display='auto'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:origin='10% 10%'/>
      </region>
      <region id="r2" style="s2">
        <set begin='00:00:10.330' end='00:00:10.670' s:display='auto'/>
        <set begin='00:00:10.330' end='00:00:10.670' s:origin='50% 10%'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:display='auto'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:origin='50% 10%'/>
      </region>
      <region id="r3" style="s3">
        <set begin='00:00:10.670' end='00:00:11.000' s:display='auto'/>
        <set begin='00:00:10.670' end='00:00:11.000' s:origin='10% 78%'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:display='auto'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:origin='10% 78%'/>
      </region>
      <region id="r4" style="s4">
        <set begin='00:00:11.000' end='00:00:11.330' s:display='auto'/>
        <set begin='00:00:11.000' end='00:00:11.330' s:origin='50% 78%'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:display='auto'/>
        <set begin='00:00:11.670' end='00:00:12.000' s:origin='50% 78%'/>
      </region>
    </layout>
  </head>
  <body>
    <div>
      <!--four speakers count off, and then all call 'Jump' together -->
      <p begin='00:00:10.000' end='00:00:10.330' region="r1" >One</p>
      <p begin='00:00:10.330' end='00:00:10.670' region="r2" >Two</p>
      <p begin='00:00:10.670' end='00:00:11.000' region="r3">Three</p>
      <p begin='00:00:11.000' end='00:00:11.330' region="r4" >Four</p>
      <p begin='00:00:11.670' end='00:00:12.000' region="r1" >Jump!</p>
      <p begin='00:00:11.670' end='00:00:12.000' region="r2" >Jump!</p>
      <p begin='00:00:11.670' end='00:00:12.000' region="r3">Jump!</p>
      <p begin='00:00:11.670' end='00:00:12.000' region="r4" >Jump!</p>
    </div>
  </body>
</tt>

Rollup and Paint on style. Content is presented a word at a time and lines scroll up in a small fixed window (typically 3 or 4 lines). The paint-on text is often embodied in roll-up content.

<p region='rollup' begin='00:00:13.000' dur='00:00:11.000'>
  <span begin='00:00:01.000'>rollup</span>
  <span begin='00:00:02.000'>style</span>
  <span begin='00:00:03.000'>caption</span>
  <span begin='00:00:04.000'>support</span>
</p>
<p region='rollup' begin='00:00:17.000' dur='00:00:11.000'>
  <span begin='00:00:01.000'>with</span>
  <span begin='00:00:02.000'>word</span>
  <span begin='00:00:03.000'>at</span>
  <span begin='00:00:04.000'>a</span>
  <span begin='00:00:05.000'>time</span>
  <span begin='00:00:06.000'>temporal</span>
</p>
<p region='rollup' begin='00:00:23.000' dur='00:00:11.000'>
  <span begin='00:00:01.000'>placement</span>
  <span begin='00:00:02.000'>this</span>
  <span begin='00:00:03.000'>could</span>
  <span begin='00:00:04.000'>go</span>
</p>
<p region='rollup' begin='00:00:27.000' dur='00:00:11.000'>
  <span begin='00:00:01.000'>on</span>
  <span begin='00:00:02.000'>all</span>
  <span begin='00:00:03.000'>day</span>
</p>

Note: As shown in the rollup example, a function of time for a k line rollup of content: The begin time of the N+kth p element is equal to the begin time plus duration of the Nth p element less the begin time of the first span in the N+kth p.

6.5 Use of Constrained TTML Feature fontFamily-generic

6.5.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#fontFamily-generic	Required with constraints	tts:fontFamily attribute	span

6.5.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

The document must use the tts:fontFamily attribute using only the following values:

Default
monospaceSerif
proportionalSerif
monospaceSansSerif
proportionalSansSerif
Casual
Cursive
Smallcap

Note: fontStyle strings(s) not bound to generic classes in TTML 1.0, such as casual, cursive and smallcap styles, may be used. These would be interpreted as local font names, if not found then the default style would be used.

A player must map the generic font names to fonts as follows

Style	Style Name	Comments
Default	Default	One of the below
monospace	Serif Monospaced with serifs	Similar to Courier
proportional	Serif Proportionally spaced with serifs	Similar to Times New Roman
monospaceSansSerif	Monospaced without serifs	Similar to Helvetica Monospaced
proportionalSansSerif	Proportionally spaced without serifs	Similar to Arial and Swiss
Casual	Casual font type	Similar to Dom and Impress
Cursive	Cursive font type	Similar to Coronet and Marigold
Smallcap	Small types	Similar to Engravers Gothic

The player must allow the user to specify a generic fontFamily for the document using the fontStyle(s) shown in the preceding table.

The player must allow the user to specify character edge attributes and types for the generic fontFamily names for the fontStyle(s) shown in the preceding table.

Note: Player and Unicode code point support is in Code Point support

6.6 Use of Constrained TTML Feature fontSize

6.6.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#fontSize	Required with constraints		span div (root)

6.6.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

document must only specify tts:fontSize(s) using a value of 50, 75%, 100%, 150% or 200%.

Note: Use of a fontSize of less than 75% (i.e. 50%) could result in unreadable content for a user.

Note: Specifying a fontSize is used for a document could allow the user to select a preferred fontSize.

Example to show how to specify an initial font.

The default font height of the player must be 5% of the root container height

Note: This is equivalent to one cell using the default grid. A player is however not required to support the grid metric.

6.7 Use of Constrained TTML Feature fontStyle-italics

6.7.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#fontStyle-italics	Required with constraints	span	span	Support 7 font family values.

6.7.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

Processors must support the capability to provide presentation semantic support for values of the tts:fontStyle attribute as defined for the fontFamily-generic feature.

Note: Various fontStyle(s) unspecified in TTML 1.0, such as casual, cursive and smallcap styles, may be used. Players that recognize the string as a particular font style could use a comparable style.

Note: A default fontStyle - white, mid-weight san serif with an initial font height of 5% of the video height and with a black outline using textOutline-unblurred of 10% of the fontSize - is suggested.

The capability must exist for the user to specify the italic style for the fontStyle(s) identified in this profile.

6.8 Use of Constrained TTML Feature length-percentage

6.8.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#length-percentage	Required

6.8.2 Constraints

None

Note: Using 10% for the tts:extent of the root container region (for example, of an 720x640 region), the equivalence to pixel units (px) could be obtained. For example, using this snippet:

<style xml:id="topLeftStyle" s:fontSize="150%" s:textAlign="left" s:backgroundColor="#ffffffff" s:color="#ff0000ff" s:origin='10% 10%' s:extent='40% 18%'/>

Convert the percentage value to a fraction (i.e. .40), multiply the numerator by 16 and divide by 100 to obtain px (pixel units).

6.9 Use of Constrained TTML Feature length-positive

6.9.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#length-positive	Required

6.9.2 Constraints

None

6.10 Use of Constrained TTML Feature styling-*

6.10.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#styling #styling-referential #styling-inline	Required with constraints

6.10.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

Styles must be applied either by reference or through use of inline styling.

Styles must be applied with a single style element using the style attribute.

Style elements must not reference other styles.

Style elements must not be child elements of region elements.

Note: The constraints in this section result in a document that contains style blocks that are complete and self-contained.

6.11 Use of Constrained TTML Feature styling-inheritance-content

6.11.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#styling-inheritance-content	Required

6.11.2 Constraints

None

6.12 Use of Constrained TTML Feature styling-inheritance-region

6.12.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#styling-inheritance-region	Required

6.12.2 Constraints

None

6.13 Use of Constrained TTML Feature textAlign-absolute

6.13.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#textAlign-absolute	Required

6.13.2 Constraints

None

6.14 Use of Constrained TTML Feature textDecoration-under

6.14.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#textDecoration-under	Required with Constraints

6.14.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

The tts:textDecoration-under attribute must support the fontStyle constraints identified in this profile.

The capability must exist for the user to specify the underline style for the fontStyle(s) identified in this profile.

Note: See also tts:fontStyle attribute.

6.15 Use of Constrained TTML Feature textOutline-unblurred

6.15.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#textOutline-unblurred	Required with Constraints

6.15.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

Character edge attributes must be expressed using textOutline-unblurred based on the settings identified in CEA-708-D, Section 8.5.8.

A text outline must be expressed using textOutline-unblurred of up to 10%.

The user must be able to specify character edge and type attributes using tts:textOutline attribute.

The user must be able to specify the rendering of character edge types of: None, raised, depressed, uniform or drop shadowed edges.

6.16 Use of Constrained TTML Feature writingMode-horizontal-lr

6.16.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#writingMode-horizontal-lr	Required

6.16.2 Constraints

None

7. Layout Constraints

7.1 Use of Constrained TTML Feature layout

7.1.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#layout	Required with constraints	region attribute	content

7.1.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

Active region(s) must not overlap.

No more than 4 region(s) must be active concurrently.

No more than four lines of text must be selected into a region at any given time.

7.2 Use of Constrained TTML Feature lineBreak-uax14

7.2.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#lineBreak-uax14	Required with constraints

7.2.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

At most 32 characters must be present in any displayed text line.

At most one p element must be selected into a region at a time.

NOTE: The fontStyle, fontSize and the characteristics of region impact how selected text flows into a region (i.e. selected text may flow outside of the region such as on a mobile device).

NOTE: Constraining one p element to a region logically places content from two different speakers to different region(s).

NOTE: When a document author wants to construct a single phrase from a speaker with more than one line in a region, the br within a p element can be used. This construction adheres to the constraints in this section. For example for one speaker with more than one line:

<p> I always get the fuzzy end<br/>of the lollipop</p>

8. Timing Constraints

8.1 Use of Constrained TTML Feature timing

8.1.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#timing	Required with constraints

8.1.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

Timing must be expressed in the hh:mm:ss.ms or hh:mm:ss:ff format used in the timeExpression.

Timing must be expressed in the same format throughout the document.

Durations (dur) shall only be used on the span element.

Note: The use of dur on a span supports rollup style content. For content other than rollup, the default behavior is to remain present until the end of the container. Therefore, durations are not needed on the span element.

For timing in hh:mm:ss.ms, the following format must be used:

Exactly 2 digits must be used in each of the hours, minutes, and second components (include leading zeros).
Exactly 3 decimal places must be used for the milliseconds component (include zeros).

<p begin='00:00:01.000' end='00:00:11.123' region="r1" >Test</p>

For timing in hh:mm:ss.ms, the following format must be used:

Exactly 2 digits shall be used in each of the hours, minutes, second, and frame components (include leading zeros).
A ttp:frameRate attribute must be present on the root element.
A ttp:frameRateMultiplier attribute may be present on the root element.

<p begin='00:00:01:00' end='00:00:11:22' region="r1" >Test</p>

8.2 Use of Constrained TTML Feature time-offset-*

8.2.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#time-offset #time-offset-with-frames	Required

8.2.2 Constraints

None

Note: Since the ttp:timebase attribute is outside of this profile, the implicit timebase used here is media as specified in TTML 1.0.

8.3 Use of Constrained TTML Feature frameRate and frameRateMultiplier

8.3.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#frameRate #frameRateMultiplier	Required

8.3.2 Constraints

See timing

8.4 Use of Constrained TTML Feature animation

8.4.1 Usage Scenario

TTML Feature	Usage type	Context of Usage	Scope	Constraint
#animation	Required with constraints

8.4.2 Constraints

Processors must support the capability to present documents where the following constraints apply:

The set element must only animate the region or span element.

The use of set elements applied to a region element must only animate the tts:display, tts:origin or tts:extent attribute.

The use of set elements applied to a span element must only animate the tts:color attribute.

No more than 6 set elements must be used within a given element

Note: Animation is constrained to the scenarios where the region needs to be moved – i.e. when the “snap” display effect is required.

Note: Animation is constrained to the scenarios to change the foreground color of content when flashing text is required.

9. Other Constraints

9.1 User Ease of Use Constraints

Constraints on reduced or simplified content are outside of this profile. External labeling could be used to support the user’s capability to select and use captions when available for:

Reduced or simplified content for “easy reader” or
Additional languages.

For example, external labeling could be used to identify simplified or reduced, or other language supported content on a text track in HTML5. Such labeling may also be used to identify when large font size is applied to content. Requirements to support user preview and retention of default or user defined settings of selected text are outside of the scope of this profile. These requirements are relevant in the environment to which the captions are deployed.

10. Features in TTML 1.0 Used in This Profile

<?xml version="1.0" encoding="utf-8"?>
<?xml version="1.0" encoding="utf-8"?>
<profile xmlns="http://www.w3.org/ns/ttml#parameter">
  <features xml:base="http://www.w3.org/ns/ttml/feature/">
    <!-- required (mandatory) feature support -->
    <feature value="required">#animation</feature>
    <feature value="required">#backgroundColor-block</feature>
    <feature value="required">#backgroundColor-inline</feature>
    <feature value="required">#color</feature>
    <feature value="required">#content</feature>
    <feature value="required">#core</feature>
    <feature value="required">#display-region</feature>
    <feature value="required">#fontFamily-generic</feature>
    <feature value="required">#fontSize</feature>
    <feature value="required">#fontStyle-italic</feature>
    <feature value="required">#frameRate</feature>
    <feature value="optional">#frameRateMultiplier</feature>
    <feature value="required">#layout</feature>
    <feature value="required">#length-percentage</feature>
    <feature value="required">#length-positive</feature>
    <feature value="required">#lineBreak-uax14</feature>
    <feature value="required">#presentation</feature>
    <feature value="required">#profile</feature>
    <feature value="required">#structure</feature>
    <feature value="required">#styling</feature>
    <feature value="required">#styling-inheritance-content</feature>
    <feature value="required">#styling-inheritance-region</feature>
    <feature value="required">#styling-inline</feature>
    <feature value="required">#styling-referential</feature>
    <feature value="required">#textAlign-absolute</feature>
    <feature value="required">#textDecoration-under</feature>
    <feature value="required">#textOutline-unblurred</feature>
    <feature value="required">#time-offset</feature>
    <feature value="required">#time-offset-with-frames</feature>
    <feature value="required">#timing</feature>
    <feature value="required">#writingMode-horizontal-lr</feature>
  </features>
</profile>

11. Error handling

A presentation process may be presented with documents that contain features that are not understood. The table that follows outlines the behavior expected under specific conditions. The pre-requisite if the caption file is syntactically valid XML.

Feature	Requirement	Action
Known	Required	must interpret
Unknown	Required	must ignore

A. Future Needs for TTML next for Simple Delivery

A.1 Values for fontFamily support

The casual, cursive and smallcap styles could be considered for addition to <genericFamilyName> expression in a future version of TTML.

B. Mapping of US Government Requirements to Constrained Profile Features

A key is provided that maps the US Government technical requirements for closed captions are mapped to the constrained features of this profile.

Presentation	#animation (set) #display-region #extent-region #frameRate #frameRateMultiplier #layout #length-percentage #length-positive #lineBreak-uax14 #textAlign-absolute #time-offset #time-offset-with-frames #timing #writingMode-lr
Character color	#animation #color
Character opacity	#color
Character size	#fontSize #fontStyle-italic #textDecoration-underline
Fonts	#fontFamily-generic #fontStyle-italic
Caption background color and opacity	#backgroundColor-*
Character edge attributes	#textOutline-unblurred
Caption window color	#backgroundColor-*
Language	#profile
Preview setting and retention	See Other Constraints,

TTML Mandatory Features

core
content
presentation
structure
time-offset
timing

TTML Features Required That Support Other Requirements

styling
styling-referential
styling-inline
styling-inheritance-content
styling-inheritance-region

C. Code points

Players should provide font glyph coverage for all characters in the “ISO 8859-1 Latin-1” space and those for ANSI INCITS 4 when mapped onto Unicode code points (see table).

Players should support the C0, G0, C1, and G1 code sets mapped onto Unicode as in the following table. See CEA 708, Section 7.1 including Table 11.

(

)

U+002_

0020

0021

0022

0023

0024

0025

0026

0027

0028

0029

002A

002B

002C

002D

002E

002F

;

U+003_

0030

0031

0032

0033

0034

0035

0036

0037

0038

0039

003A

003B

003C

003D

003E

003F

U+004_

0040

0041

0042

0043

0044

0045

0046

0047

0048

0049

004A

004B

004C

004D

004E

004F

[

]

U+005_

0050

0051

0052

0053

0054

0055

0056

0057

0058

0059

005A

005B

005C

005D

005E

005F

U+006_

0060

0061

0062

0063

0064

0065

0066

0067

0068

0069

006A

006B

006C

006D

006E

006F

{

}

♪

U+007_

0070

0071

0072

0073

0074

0075

0076

0077

0078

0079

007A

007B

007C

007D

007E

007F

U+00A_

00A0

00A1

00A2

00A3

00A4

00A5

00A6

00A7

00A8

00A9

00AA

00AB

00AC

00AD

00AE

00AF

U+00B_

00B0

00B1

00B2

00B3

00B4

00B5

00B6

00B7

00B8

00B9

00BA

00BB

00BC

00BD

00BE

00BF

U+00C_

00C0

00C1

00C2

00C3

00C4

00C5

00C6

00C7

00C8

00C9

00CA

00CB

00CC

00CD

00CE

00CF

U+00D_

00D0

00D1

00D2

00D3

00D4

00D5

00D6

00D7

00D8

00D9

00DA

00DB

00DC

00DD

00DE

00DF

U+00E_

00E0

00E1

00E2

00E3

00E4

00E5

00E6

00E7

00E8

00E9

00EA

00EB

00EC

00ED

00EE

00EF

U+00F_

00F0

00F1

00F2

00F3

00F4

00F5

00F6

00F7

00F8

00F9

00FA

00FB

00FC

00FD

00FE

00FF

U+015_

0152

0153

U+016_

0160

0161

U+017_

0178

017D

017E

U+019_

0192

U+02D_

02DC

‐

―

‖

U+201_

2010

2015

2016

‧

U+202_

2027

‰

›

U+203_

2030

203A

₡

₢

€

U+20A_

20A1

20A2

20AC

₳

U+20B_

20B3

°C

°F

U+210_

2103

2109

⅓

⅟

U+215_

2153

215F

□

U+25A_

25A1

♩

♫

U+266_

2669

266B

Players may support the extended G2 characters sets that map onto Unicode code points (See table).

708 Code(s)	glyph	Unicode	Unicode Description
7F	♪	266A	Eighth Note
1025	…	2026	Horizontal ellipsis
102A	Š	0160	Latin capital letter S with caron
102C	OE	0152	Latin capital ligature OE
1030	█	2588	Full block
1031	‘	2018	Left single quotation mark
1032	‘	2019	Right single quotation mark
1033	“	201C	Left double quotation mark
1034	“	201D	Right double quotation mark
1035	•	2022	Bullet
1039	™	2122	Trade mark sign
103A	š	0161	Latin small letter S with caron
103C	oe	0153	Latin small ligature OE
103D	℠	2120	Service mark sign
103F	Ÿ	0178	Latin capital letter Y with dieresis
1076	⅛	215B	Vulgar fraction one eighth
1077	⅜	215C	Vulgar fraction three eighths
1078	⅝	215D	Vulgar fraction five eighths
1079	⅞	215E	Vulgar fraction seven eighths
107A	│	2502	Box drawings light vertical
107B	┐	2510	Box drawings light down and left
107C	└	2514	Box drawings light up and right
107D	─	2500	Box drawings light horizontal
107E	┘	2518	Box drawings light up and left
107F	┌	250C	Box drawings light down and right

Players may also provide Glyph coverage for additional Unicode code points

D. Color values

For color values of the form #rrggbbaa, players must support combinations where the rr, gg, bb components may be either 00 or ff; and the aa component may be 00, 54, A8 or FF. e.g: #00ffff54. Additionally players should support values for rr, gg, and bb of 54 or A8, and may support all possible values between 00 to ff.

Color	Value
Black	#000000ff
White	#fffffffff
Red	#ff0000ff
Green	#00ff00ff
Blue	#0000ffff
Yellow	#ffff00ff
Magenta	#ff00ffff
Cyan	#00ffffff

E. Acknowledgements

Many thanks to Robin Berjon for providing the respec.js tool used to format this document.

Simple Delivery Profile for Closed Captions

A profile of TTML for internet delivery

W3CNote 12 July 2012

Abstract

Status of This Document

Table of Contents

1. Conformance

Simple Delivery Profile for Closed Captions

2. Terms and Definitions

3. Simple Delivery Profile for Closed Captions

3.1 Use of TTML Constrained Feature Template

Usage Scenario

Usage Constraints

4. Structural Constraints

5. Constrained Features

5.1 Use of Constrained TTML Feature core

5.1.1 Usage Scenario

5.1.2 Constraints

5.2 Use of Constrained TTML Feature content

5.2.1 Usage Scenario

5.2.2 Constraints

5.3 Use of Constrained TTML Feature presentation

5.3.1 Usage Scenario

5.3.2 Constraints

5.4 Use of Constrained TTML Feature profile

5.4.1 Usage Scenario

5.4.2 Constraints

5.5 Use of Constrained TTML Feature structure

5.5.1 Usage Scenario

5.5.2 Constraints

6. Style Constraints

6.1 Use of Constrained TTML Feature backgroundColor-*

6.1.1 Usage Scenario

6.1.2 Constraints

6.2 Use of Constrained TTML Feature color

6.2.1 Usage Scenario

6.2.2 Constraints

6.3 Use of Constrained TTML Feature display-region

6.3.1 Usage Scenario

6.3.2 Constraints

6.4 Use of Constrained TTML Feature display-region

6.4.1 Usage Scenario

6.4.2 Constraints

6.5 Use of Constrained TTML Feature fontFamily-generic

6.5.1 Usage Scenario

6.5.2 Constraints

6.6 Use of Constrained TTML Feature fontSize

6.6.1 Usage Scenario

6.6.2 Constraints

6.7 Use of Constrained TTML Feature fontStyle-italics

6.7.1 Usage Scenario

6.7.2 Constraints

6.8 Use of Constrained TTML Feature length-percentage

6.8.1 Usage Scenario

6.8.2 Constraints

6.9 Use of Constrained TTML Feature length-positive

6.9.1 Usage Scenario

6.9.2 Constraints

6.10 Use of Constrained TTML Feature styling-*

6.10.1 Usage Scenario

6.10.2 Constraints

6.11 Use of Constrained TTML Feature styling-inheritance-content

6.11.1 Usage Scenario

6.11.2 Constraints

6.12 Use of Constrained TTML Feature styling-inheritance-region

6.12.1 Usage Scenario

6.12.2 Constraints

6.13 Use of Constrained TTML Feature textAlign-absolute

6.13.1 Usage Scenario

6.13.2 Constraints

6.14 Use of Constrained TTML Feature textDecoration-under

6.14.1 Usage Scenario

6.14.2 Constraints

6.15 Use of Constrained TTML Feature textOutline-unblurred

6.15.1 Usage Scenario

6.15.2 Constraints

6.16 Use of Constrained TTML Feature writingMode-horizontal-lr

6.16.1 Usage Scenario

6.16.2 Constraints

7. Layout Constraints