See attached.
Silvia.
Presentation at Video Accessibility Workshop, 1st November 2009
Dr Silvia Pfeiffer
Mozilla/Xiph/Annodex/Vquence
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User Requirements: Video Accessibility
* accessibility of the <video> and <audio> element (solved)
* needs for hard of hearing (HoH):
- captions
- signing video
- signing captions (!)
* needs for foreigners:
- subtitles
* needs for vision impaired (VI):
- audio descriptions
- textual audio descriptions (timed transcript!) with screen reader
- textual audio descriptions (timed transcript!) with braille
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Related Video/Audio User Requirements
* usability:
- ticker text
- active regions (timed)
- chapter breakdown (cue ranges)
* searchability:
- annotations
- timed metadata
- timed transcript
* entertainment/education:
- karaoke
- lyrics
- linguistic markup
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Technical Requirements
Videa a11y creates more content tracks for video
* support of multi-track audio/video files
* support of multiple text tracks in video files
* standard JavaScript and DOM interface to a/v/t tracks
* content negotiation with server on required tracks
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Technical Requirements
Text tracks are special: text should be text and not binary
* edit-ability: crowd source text tracks
* integration: CMS requires text in DB
* extensibility: text track from other server/organisation
* sharability: embedding of video with associated text tracks
Requirement for an extension of HTML5 <video> to relate to external text tracks
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Proposal: <itext> element (V1)
<video src="example.ogv" poster="example.png" controls>
<itext lang="en" type="text/srt" charset="ISO-8859-1" display="auto"
src="example.english.srt" category="SUB"></itext>
<itext lang="es-mx" type="text/srt" charset="ISO-8859-1" display="auto"
src="example.spanish-us.srt" category="SUB"></itext>
<itext lang="zh" type="text/srt" charset="GB18030" display="auto"
src="example.chinese.srt" category="SUB"></itext>
<itext lang="ja" type="text/srt" charset="EUC-JP" display="auto"
src="example.japanese-euc.srt" category="SUB"></itext>
<itext lang="en" type="text/srt" charset="ISO-8859" display="yes"
src="audiodescription.srt" category="TAD"></itext>
<itext lang="en" type="text/srt" charset="ISO-8859" display="yes"
src="chapters.srt" category="CUE"></itext>
</video>
https://wiki.mozilla.org/Accessibility/HTML5_captions
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Categories
* CC: closed captions
* SUB: subtitles
* TAD: textual audio descriptions
* KTV: karaoke
* TIK: ticker text
* AR: active regions
* NB: semantic annotations, including speech bubbles and director comments
* META: metadata, mostly machine-readable
* TRX: transcripts / scripts
* LRC: lyrics
* LIN: linguistic markup
* CUE: cue points, DVD style chapter markers and similar navigational landmarks
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Demo: http://www.annodex.net/~silvia/itext/elephant_no_skin.html
* Note: extra menu
* Note: textual audio description
* Note: default display styles
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Analysis of the time-aligned text formats:
- sequence of text segments with start/end time markers
- potentially spatial positioning
- potentially styling
- default position, if visible
- default language
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Multitrack text support in Ogg
Demo: Firefox and Ogg Kate
file:///Users/silvia/Sites/mozilla/itext/elephants_dream/multitrack/elephant.vat_en_t_fr_t_de_t_sp.ogv
* Note: integrated menu
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Common JavaScript Interface
void fetch();
DOMString currentText(currentTime);
void enable();
void disable();
void delay(seconds);
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Proposal: <itext> element (V2)
<video class="v" src="elephants_dream/elephant.ogv"
poster="elephants_dream/elephant.png" >
<itextlist category="SUB">
<itext lang="en" type="text/srt" charset="ISO-8859-1"
src="example.english.srt">
</itext>
<itext lang="es-mx" type="text/srt" charset="ISO-8859-1"
src="example.spanish-us.srt">
</itext>
<itext lang="zh" type="text/srt" charset="GB18030"
src="example.chinese.srt">
</itext>
<itext lang="ja" type="text/srt" charset="EUC-JP"
src="example.japanese-euc.srt">
</itext>
</itextlist>
<itextlist category="TAD">
<itext lang="en" type="text/srt" charset="ISO-8859"
src="audiodescription.srt">
</itext>
</itextlist>
<itextlist category="SUB">
<itext lang="en" type="text/srt" charset="ISO-8859"
src="chapters.srt"></itext>
</itextlist>
https://wiki.mozilla.org/Accessibility/HTML5_captions_v2
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Demo: http://www.annodex.net/~silvia/itext/elephant_no_skin_v2.html
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Common JavaScript Interface:
iTextList:
attribute Function onenter;
attribute Function onleave;
iText:
interface HTMLItextElement : HTMLElement {
attribute DOMString src;
attribute DOMString lang;
attribute DOMString type;
attribute DOMString charset;
attribute float delay;
attribute unsigned long stretch;
readonly attribute boolean fetched;
readonly attribute ItextError error;
readonly attribute HTMLCollection allText;
readonly attribute langName;
DOMString currentText(currentTime);
};
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Demo: http://oggify.com/
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Proposal: Discuss text / itextlist proposal and move forward with specification
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My demos are at: http://www.annodex.net/~silvia/itext/
Thanks.
