--- a/ttml-ww-profiles/ttml-ww-profiles.source.html Mon Jul 28 15:51:29 2014 +0200
+++ b/ttml-ww-profiles/ttml-ww-profiles.source.html Thu Jul 31 15:45:00 2014 +0200
@@ -72,11 +72,26 @@
</section>
<section id="conformance">
- <p>A subtitle document SHALL conform to a profile defined herein if it meets all normative provisions associated with the
+ <p>A subtitle document that conforms to a profile defined herein SHALL satisfy all normative provisions specified by the
profile.</p>
- <p>A TTML presentation processor SHALL conform to a profile if it is capable of presenting any subtitle document conforming to
- the profile, i.e. if it implements all features and provisions of the profile</p>
+ <p>A presentation processor that conforms to a profile defined herein SHALL:</p>
+
+ <ul>
+ <li>satisfy all normative provisions specified by the profile; and</li>
+
+ <li>be capable of presenting any subtitle document that conforms to the profile, i.e. if it implements all features and
+ provisions of the profile.</li>
+ </ul>
+
+ <p>A transformation processor that conforms to a profile defined herein SHALL:</p>
+
+ <ul>
+ <li>satisfy all normative provisions specified by the profile; and</li>
+
+ <li>be capable of transforming any subtitle document that conforms to the profile, i.e. if it implements all features and
+ provisions of the profile.</li>
+ </ul>
</section>
<section id='profiles'>
@@ -86,29 +101,31 @@
<h3>General</h3>
<p>A subtitle document SHALL NOT conform to the Text and Image Profiles simultaneously.</p>
-
- <p>In applications that require subtitle/caption content in image form to be simultaneously available in text form, two distinct subtitle documents, one conforming to the Text Profile and the other conforming to the Image Profile, SHOULD be offered. In addition, the Text Profile subtitle document SHOULD be associated with the Image Profile subtitle document such that, when image content is encountered, assistive technologies have access to its corresponding text form.</p>
-
-
- <p class='note'>The <code>ittm:altText</code> element specified <a href='#ttm-altText'></a> also allows text equivalent string to be associated with an image, e.g. to support indexation of the content and also facilitate quality checking of the document during authoring.</p>
-
-
- <p>Annex <a href='#wcag-applications'></a> specifically discusses this specification in the context of the [[WCAG20]] guidelines.</a>
-
+
+ <p>In applications that require subtitle/caption content in image form to be simultaneously available in text form, two
+ distinct subtitle documents, one conforming to the Text Profile and the other conforming to the Image Profile, SHOULD be
+ offered. In addition, the Text Profile subtitle document SHOULD be associated with the Image Profile subtitle document such
+ that, when image content is encountered, assistive technologies have access to its corresponding text form.</p>
+
+ <p class='note'>The <code>ittm:altText</code> element specified <a href='#ttm-altText'></a> also allows text equivalent
+ string to be associated with an image, e.g. to support indexation of the content and also facilitate quality checking of the
+ document during authoring.</p>
+
+ <p>Annex <a href='#wcag-applications'></a> specifically discusses this specification in the context of the [[WCAG20]]
+ guidelines.</p>
</section>
<section>
<h3>Text Profile</h3>
- <p>A subtitle document conforming to the Text Profile SHALL conform to Sections <a href="#common-constraints"></a> and
- <a href="#text-profile-constraints"></a>.</p>
+ <p>The Text Profile consists of Sections <a href="#common-constraints"></a> and <a href="#text-profile-constraints"></a>.</p>
</section>
<section>
<h3>Image Profile</h3>
- <p>A subtitle document conforming to the Image Profile SHALL conform to Sections <a href="#common-constraints"></a> and
- <a href="#image-profile-constraints"></a>.</p>
+ <p>The Image Profile consists of Sections <a href="#common-constraints"></a> and <a href=
+ "#image-profile-constraints"></a>.</p>
</section>
</section>
@@ -209,8 +226,8 @@
<td><em>This specification</em></td>
</tr>
-
- <tr>
+
+ <tr>
<td>IMSC 1.0 Metadata</td>
<td>ittm</td>
@@ -268,15 +285,22 @@
<p>Each intermediate synchronic document of the subtitle document is intended to be displayed on a specific frame and removed
on a specific frame of the related video object.</p>
-
- <p>When mapping a media time expression M to a frame F of a related video object, e.g. for the purpose of rendering a subtitle document onto the related video object, a presentation processor SHALL map M to the frame F with the presentation time that is the closest to, but not less, than M.</p>
-
+
+ <p>When mapping a media time expression M to a frame F of a related video object, e.g. for the purpose of rendering a
+ subtitle document onto the related video object, a presentation processor SHALL map M to the frame F with the presentation
+ time that is the closest to, but not less, than M.</p>
+
<aside class="example">
A media time expression of 00:00:05.1 corresponds to frame ceiling(5.1 × ( 1000 / 1001 × 30) = 153 of a related video
object with a frame rate of 1000 / 1001 × 30 ≈ 29.97.
</aside>
-
- <p class="note">In typical scenario, the same video program (the related video object) will be used for subtitle document authoring, delivery and user playback. The mapping from media time expression to related video object above allows the author to precisely associate subtitle video content with video frames, e.g. around scene transitions. In circumstances where the video program is downsampled during delivery, the application can specify that, at playback, the relative video object be considered the delivered video program upsampled to is original rate, thereby allowing subtitle content to be rendered at the same temporal locations it was authored.</p>
+
+ <p class="note">In typical scenario, the same video program (the related video object) will be used for subtitle document
+ authoring, delivery and user playback. The mapping from media time expression to related video object above allows the author
+ to precisely associate subtitle video content with video frames, e.g. around scene transitions. In circumstances where the
+ video program is downsampled during delivery, the application can specify that, at playback, the relative video object be
+ considered the delivered video program upsampled to is original rate, thereby allowing subtitle content to be rendered at the
+ same temporal locations it was authored.</p>
<p>If <code>ttp:frameRate</code> is specified, then the product of <code>ttp:frameRate</code> and
<code>ttp:frameRateMultiplier</code> SHALL be the frame rate of the related video object.</p>
@@ -382,9 +406,15 @@
<section id='tts-forcedDisplay'>
<h4>itts:forcedDisplay</h4>
- <p><code>itts:forcedDisplay</code> identifies forced content, which represents audio (e.g. foreign language) or text (e.g. a sign) that is not translated in the audio/video presentation. The presentation of elements based their computed <code>itts:forcedDisplay</code> value is controlled using the <code>displayForcedOnlyMode</code> application parameter. Annex <a href='#forced-content'></a> illustrates the use of <code>itts:forcedDisplay</code>.</p>
-
- <table class="simple">
+ <p><code>itts:forcedDisplay</code> allows the processor to override the computed value of <code>itts:forcedDisplay</code>
+ attribute in conjunction with an application parameter <code>displayForcedOnlyMode</code>.</p>
+
+ <p>If the value of <code>displayForcedOnlyMode</code> is "true", a content element with a
+ <code>itts:forcedDisplay</code> computed value of "false" shall be assumed to have a <code>tts:visibility</code>
+ computed value equal to "hidden", even if <code>tts:visibility</code> would otherwise be computed to
+ "true".</p>
+
+ <table class="simple">
<colgroup>
<col style="width:25%" span="1">
<col span="1">
@@ -428,27 +458,40 @@
</tr>
</tbody>
</table>
-
- <p>The presentation processor SHALL accept an optional boolean parameter called <code>displayForcedOnlyMode</code>, whose value MAY be set by the application. If not set, the value of <code>displayForcedOnlyMode</code> SHALL be assumed to be equal to "false".</p>
-
- <p>If the value of <code>displayForcedOnlyMode</code> is "true", a content element with a <code>itts:forcedDisplay</code> computed value of "false" shall be assumed to have a <code>tts:visibility</code> computed value equal to "hidden", even if <code>tts:visibility</code> is otherwise set to "true".</p>
-
- <p class='note'>A region will remain visible even if all content elements have a computed <code>tts:visibility</code> value of "hidden" unless <code>tts:showBackground</code> is set to "whenActive" (the initial value of <code>tts:showBackground</code> is "always".)</p>
-
+
+ <p>Annex <a href='#forced-content'></a> illustrates the use of <code>itts:forcedDisplay</code> in an application in which a
+ single document contains both hard of hearing captions and translated foreign language subtitles, using
+ <code>itts:forcedDisplay</code> to display translation subtitles always, independently of whether the hard of hearing
+ captions are displayed or hidden.</p>
+
+ <p>The presentation processor SHALL accept an optional boolean parameter called <code>displayForcedOnlyMode</code>, whose
+ value MAY be set by a context external to the presentation processor. If not set, the value of
+ <code>displayForcedOnlyMode</code> SHALL be assumed to be equal to "false".</p>
+
+ <p>The algorithm for setting the <code>displayForcedOnlyMode</code> parameter based on the circumstances under which the
+ subtitle document is presented is left to the application.</p>
+
+ <p class='note'>A region will remain visible even if all content elements have a computed <code>tts:display</code> value of
+ "none" unless <code>tts:showBackground</code> is set to "whenActive" (the initial value of
+ <code>tts:showBackground</code> is "always".)</p>
+
<p class='note'>Although <code>itts:forcedDisplay</code>, like all the TTML style attributes, has no defined semantics on a
<code>br</code> content element, <code>itts:forcedDisplay</code> will apply to a <code>br</code> content element if it is
either defined on an ancestor content element of the <code>br</code> content element or it is applied to a region element
corresponding to a region that the <code>br</code> content element is being flowed into.</p>
-
- <p class='note'>It is expected that the functionality of <code>itts:forcedDisplay</code> will be mapped to a conditional style construct in a future revision of this specification.</p>
+
+ <p class='note'>It is expected that the functionality of <code>itts:forcedDisplay</code> will be mapped to a conditional
+ style construct in a future revision of this specification.</p>
</section>
-
- <section id='ttm-altText'>
+
+ <section id='ttm-altText'>
<h4>ittm:altText</h4>
- <p><code>ittm:altText</code> allows an author to provide a text string equivalent for an element, typically an image. This text equivalent MAY be used to support indexation of the content and also facilitate quality checking of the document during authoring.</p>
-
- <p>The <code>ittm:altText</code> element SHALL conform to the following syntax:</p>
+ <p><code>ittm:altText</code> allows an author to provide a text string equivalent for an element, typically an image. This
+ text equivalent MAY be used to support indexation of the content and also facilitate quality checking of the document
+ during authoring.</p>
+
+ <p>The <code>ittm:altText</code> element SHALL conform to the following syntax:</p>
<table class="syntax">
<tbody>
@@ -469,14 +512,14 @@
</tr>
</tbody>
</table>
-
- <p><a href="#image-profile-constraints"></a> specifies the use of the <code>ittm:altText</code> element with images.</p>
-
- <p class='note'>In contrast to the common use of <code>alt</code> attributes in [[HTML5]], the <code>ittm:altText</code> attribute content is not intended to be displayed in place of the element if the element is not loaded. The <code>ittm:altText</code> attribute content can however be read and used by assistive technologies.</code>
- .</p>
+
+ <p><a href="#image-profile-constraints"></a> specifies the use of the <code>ittm:altText</code> element with images.</p>
+
+ <p class='note'>In contrast to the common use of <code>alt</code> attributes in [[HTML5]], the <code>ittm:altText</code>
+ attribute content is not intended to be displayed in place of the element if the element is not loaded. The
+ <code>ittm:altText</code> attribute content can however be read and used by assistive technologies. .</p>
</section>
-
- </section>
+ </section>
<section>
<h3>Region</h3>
@@ -964,8 +1007,8 @@
<td>MAY be used.</td>
</tr>
-
- <tr>
+
+ <tr>
<td><code>#altText</code></td>
<td>MAY be used.</td>
@@ -1348,7 +1391,8 @@
<section>
<h4>Definition</h4>
- <p>A presented image is a <code>div</code> element with a <code>smpte:backgroundImage</code> attribute that does not extend beyond a presented region.</p>
+ <p>A presented image is a <code>div</code> element with a <code>smpte:backgroundImage</code> attribute that does not extend
+ beyond a presented region.</p>
</section>
<section>
@@ -1363,18 +1407,19 @@
<h3><code>div</code> element</h3>
<p>If a <code>smpte:backgroundImage</code> attribute is applied to a <code>div</code> element:</p>
-
- <ul>
- <li>
- the width and height of the region extent associated with the <code>div</code> element SHALL be specified and SHALL be equal to the width and height of the image source referenced by the <code>smpte:backgroundImage</code>;
- </li>
- <li>
- the <code>metadata</code> element of the <code>div</code> element SHOULD contain an instance of <code>ittm:altText</code> that is a verbatim text equivalent of the image referenced by the <code>smpte:backgroundImage</code> attribute; and
- </li>
- <li>
- The <code>smpte:backgroundImage</code> attribute SHALL reference a complete image that conforms to the PNG image coding as specified in Sections 7.1.1.3 and 15.1 of [[!MHP]]. If a pHYs chunk is present, it SHALL indicate square pixels. Note: If no pixel aspect ratio is carried, the default of square pixels is assumed.<br>
- </li>
- </ul>
+
+ <ul>
+ <li>the width and height of the region extent associated with the <code>div</code> element SHALL be specified and SHALL be
+ equal to the width and height of the image source referenced by the <code>smpte:backgroundImage</code>;</li>
+
+ <li>the <code>metadata</code> element of the <code>div</code> element SHOULD contain an instance of
+ <code>ittm:altText</code> that is a verbatim text equivalent of the image referenced by the
+ <code>smpte:backgroundImage</code> attribute; and</li>
+
+ <li>The <code>smpte:backgroundImage</code> attribute SHALL reference a complete image that conforms to the PNG image coding
+ as specified in Sections 7.1.1.3 and 15.1 of [[!MHP]]. If a pHYs chunk is present, it SHALL indicate square pixels. Note:
+ If no pixel aspect ratio is carried, the default of square pixels is assumed.<br></li>
+ </ul>
</section>
<section>
@@ -1526,13 +1571,11 @@
</tr>
<tr>
-
<td><code>#image</code></td>
<td><code>smpte:backgroundImage</code> MAY be used.<br>
<code>smpte:backgroundImageHorizontal</code> and <code>smpte:backgroundImageVertical</code> SHALL NOT be used.<br>
<code>smpte:image</code> SHALL NOT be used.</td>
-
</tr>
</tbody>
</table>
@@ -2368,44 +2411,64 @@
</tbody>
</table>
</section>
-
- <section class='appendix' id='forced-content'>
-
- <h2>Forced content</code></h2>
-
- <p><a href='#fig-forced-content'></a> below illustrates the use of forced content, i.e. <code>itts:forcedDisplay</code> and <code>displayForcedOnlyMode</code>. The content with <code>itts:forcedDisplay</code>="true" is the French translation of the "High School" sign. The content with <code>itts:forcedDisplay</code>="false" are French subtitles capturing a voiceover.</p>
-
- <figure id='fig-forced-content'>
- <img src="forced-example-figure-1.png" alt="Illustration of the use of itts:forcedDisplay">
-
- <figcaption>
- Illustration of the use of itts:forcedDisplay
- </figcaption>
- </figure>
-
- <p>When the user selects French as the playback language but does not select French subtitles, <code>displayForcedOnlyMode</code> is set to "true", causing the display of the sign translation, which is useful to any French speaker, but hiding the voiceover subtitles as the voiceover is heard in French.</p>
-<p>If the user selects French as the playback language and also selects French subtitles, e.g. if the user is hard-of-hearing, <code>displayForcedOnlyMode</code> is set to "false", causing the display of both the sign translation and the voiceover subtitles.</p>
-
-<p>The algorithm for selecting the value <code>displayForcedOnlyMode</code> and the appropriate combination of subtitle and audio tracks is not specified here and left to the application.</p>
- </section>
-
-
- <section class='appendix' id='wcag-applications'>
+
+ <section class='appendix' id='forced-content'>
+ <h2>Forced content (informative)</h2>
+
+ <p><a href='#fig-forced-content'></a> below illustrates the use of forced content, i.e. <code>itts:forcedDisplay</code> and
+ <code>displayForcedOnlyMode</code>. The content with <code>itts:forcedDisplay</code>="true" is the French translation
+ of the "High School" sign. The content with <code>itts:forcedDisplay</code>="false" are French subtitles
+ capturing a voiceover.</p>
+
+ <figure id='fig-forced-content'>
+ <img src="forced-example-figure-1.png" alt="Illustration of the use of itts:forcedDisplay">
+
+ <figcaption>
+ Illustration of the use of itts:forcedDisplay
+ </figcaption>
+ </figure>
+
+ <p>When the user selects French as the playback language but does not select French subtitles,
+ <code>displayForcedOnlyMode</code> is set to "true", causing the display of the sign translation, which is useful to
+ any French speaker, but hiding the voiceover subtitles as the voiceover is heard in French.</p>
+
+ <p>If the user selects French as the playback language and also selects French subtitles, e.g. if the user is hard-of-hearing,
+ <code>displayForcedOnlyMode</code> is set to "false", causing the display of both the sign translation and the
+ voiceover subtitles.</p>
+
+ <p>The algorithm for setting the <code>displayForcedOnlyMode</code> parameter and selecting the appropriate combination of
+ subtitle and audio tracks depends on the application.</p>
+ </section>
+
+ <section class='appendix' id='wcag-applications'>
<h2>WCAG Considerations</h2>
-
- <p>In order to meet the guidelines in [[!WCAG20]], the following considerations apply.</p>
-
- <p>
-Guideline 1.1 of [[!WCAG20]] recommends that an implementation provide text alternatives for all non-text content. In the context of this specification, this text alternative is intended primarily to support users of the subtitles who cannot see images. Since the images of an Image Profile subtitle document usually represent subtitle or caption text, the guidelines for authoring text equivalent strings given at <span class='sec-no'>Images of text</span> of [[HTML5]] are appropriate.</p>
-
- <p>
-Thus, for each subtitle in an Image Profile subtitle document, a text equivalent content in a Text Profile subtitle document SHOULD be written so that it conveys all essential content and fulfills the same function as the corresponding subtitle image. In the context of subtitling and captioning, this content will be (as a minimum) the verbatim equivalent of the image without précis or summarization. However, the author MAY include extra information to the text equivalent string in cases where styling is applied to the text image with a deliberate connotation, as a <em>functional</em> replacement for the applied style.</p>
-
-<p>For instance, in subtitling and captioning, italics can be used to indicate an off screen speaker context (for example a voice from a radio). An author can choose to include this functional information in the text equivalent; for example, by including the word "Radio: " before the image equivalent text. It should also be noted that images in an Image Profile subtitle document that are intended for use as <em>captions</em>, i.e. intended for a hard of hearing audience, might already include this functional information in the rendered text.</p>
-
-<p>Guideline 1.1 of [[!WCAG20]] also recommends that accessible text alternatives must be "programmatically determinable." This means that the text must be able to be read and used by the assistive technologies (and the accessibility features in browsers) that people with disabilities use. It also means that the user must be able to use their assistive technology to find the alternative text (that they can use) when they land on the non-text content (that they can't use).</p>
-
- </section>
+
+ <p>In order to meet the guidelines in [[!WCAG20]], the following considerations apply.</p>
+
+ <p>Guideline 1.1 of [[!WCAG20]] recommends that an implementation provide text alternatives for all non-text content. In the
+ context of this specification, this text alternative is intended primarily to support users of the subtitles who cannot see
+ images. Since the images of an Image Profile subtitle document usually represent subtitle or caption text, the guidelines for
+ authoring text equivalent strings given at <span class='sec-no'>Images of text</span> of [[HTML5]] are appropriate.</p>
+
+ <p>Thus, for each subtitle in an Image Profile subtitle document, a text equivalent content in a Text Profile subtitle document
+ SHOULD be written so that it conveys all essential content and fulfills the same function as the corresponding subtitle image.
+ In the context of subtitling and captioning, this content will be (as a minimum) the verbatim equivalent of the image without
+ précis or summarization. However, the author MAY include extra information to the text equivalent string in cases where
+ styling is applied to the text image with a deliberate connotation, as a <em>functional</em> replacement for the applied
+ style.</p>
+
+ <p>For instance, in subtitling and captioning, italics can be used to indicate an off screen speaker context (for example a
+ voice from a radio). An author can choose to include this functional information in the text equivalent; for example, by
+ including the word "Radio: " before the image equivalent text. It should also be noted that images in an Image
+ Profile subtitle document that are intended for use as <em>captions</em>, i.e. intended for a hard of hearing audience, might
+ already include this functional information in the rendered text.</p>
+
+ <p>Guideline 1.1 of [[!WCAG20]] also recommends that accessible text alternatives must be "programmatically
+ determinable." This means that the text must be able to be read and used by the assistive technologies (and the
+ accessibility features in browsers) that people with disabilities use. It also means that the user must be able to use their
+ assistive technology to find the alternative text (that they can use) when they land on the non-text content (that they
+ can't use).</p>
+ </section>
<section class='appendix' id='features-and-extensions'>
<h2>Extensions</h2>
@@ -2420,47 +2483,42 @@
<section class='appendix'>
<h3>#progressivelyDecodable</h3>
- <p>A TTML transformation processor supports the <code>#progressivelyDecodable</code> feature if it recognizes and is capable
- of transforming values of the <a href="#ttp-progressivelyDecodable"><code>ittp:progressivelyDecodable</code></a>.</p>
-
- <p>A TTML presentation processor supports the <code>#progressivelyDecodable</code> feature if it implements presentation
- semantic support for values of the <a href="#ttp-progressivelyDecodable"><code>ittp:progressivelyDecodable</code></a>
- attribute.</p>
+ <p>A transformation processor supports the <code>#progressivelyDecodable</code> feature if it recognizes and is capable of
+ transforming values of the <a href="#ttp-progressivelyDecodable"><code>ittp:progressivelyDecodable</code></a>.</p>
+
+ <p>A presentation processor supports the <code>#progressivelyDecodable</code> feature if it implements presentation semantic
+ support for values of the <a href="#ttp-progressivelyDecodable"><code>ittp:progressivelyDecodable</code></a> attribute.</p>
</section>
<section class='appendix'>
<h3>#aspectRatio</h3>
- <p>A TTML transformation processor supports the <code>#aspectRatio</code> feature if it recognizes and is capable of
- transforming values of the <a href="#ttp-aspectRatio"><code>ittp:aspectRatio</code></a>.</p>
-
- <p>A TTML presentation processor supports the <code>#aspectRatio</code> feature if it implements presentation semantic
- support for values of the <a href="#ttp-aspectRatio"><code>ittp:aspectRatio</code></a> attribute.</p>
+ <p>A transformation processor supports the <code>#aspectRatio</code> feature if it recognizes and is capable of transforming
+ values of the <a href="#ttp-aspectRatio"><code>ittp:aspectRatio</code></a>.</p>
+
+ <p>A presentation processor supports the <code>#aspectRatio</code> feature if it implements presentation semantic support for
+ values of the <a href="#ttp-aspectRatio"><code>ittp:aspectRatio</code></a> attribute.</p>
</section>
<section class='appendix'>
<h3>#forcedDisplay</h3>
- <p>A TTML transformation processor supports the <code>#forcedDisplay</code> feature if it recognizes and is capable of
+ <p>A transformation processor supports the <code>#forcedDisplay</code> feature if it recognizes and is capable of
transforming values of the <a href="#tts-forcedDisplay"><code>itts:forcedDisplay</code></a>.</p>
- <p>A TTML presentation processor supports the <code>#forcedDisplay</code> feature if it implements presentation semantic
- support for values of the <a href="#tts-forcedDisplay"><code>itts:forcedDisplay</code></a> attribute.</p>
+ <p>A presentation processor supports the <code>#forcedDisplay</code> feature if it implements presentation semantic support
+ for values of the <a href="#tts-forcedDisplay"><code>itts:forcedDisplay</code></a> attribute.</p>
</section>
-
- <section class='appendix'>
+
+ <section class='appendix'>
<h3>#altText</h3>
- <p>A TTML transformation processor supports the <code>#altText</code> feature if it recognizes and is capable of
- transforming values of the <a href="#ttm-altText"><code>ittm:altText</code></a> element.</p>
-
- <p>A TTML presentation processor supports the <code>#altText</code> feature if it implements presentation semantic
- support for values of the <a href="#ttm-altText"><code>ittm:altText</code></a> element.</p>
+ <p>A transformation processor supports the <code>#altText</code> feature if it recognizes and is capable of transforming
+ values of the <a href="#ttm-altText"><code>ittm:altText</code></a> element.</p>
+
+ <p>A presentation processor supports the <code>#altText</code> feature if it implements presentation semantic support for
+ values of the <a href="#ttm-altText"><code>ittm:altText</code></a> element.</p>
</section>
-
- </section>
-
-
</section>
</body>
</html>