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Accessibility/Video a11y requirements: Difference between revisions
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Accessibility/Video a11y requirements (view source)
Revision as of 18:45, 5 November 2008
, 5 November 2008added section on specification language
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* For text that can be toggled on, default icons need to be specified. | * For text that can be toggled on, default icons need to be specified. | ||
* Use style sheet mechanisms and style tags for displayable text. | * Use style sheet mechanisms and style tags for displayable text - maybe select a simple subpart of CSS to provide styling. | ||
[http://www.masternewmedia.org/news/2007/02/06/subtitling_and_dubbing_your_internet.htm Here] is an example of two services that have solved the display challenge. | [http://www.masternewmedia.org/news/2007/02/06/subtitling_and_dubbing_your_internet.htm Here] is an example of two services that have solved the display challenge. | ||
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* An alternative is to enable the inclusion of a hyperlink for a fragment of time and display in some special way that a hyperlink is present. (see e.g. [http://annodex.net/TR/draft-pfeiffer-cmml-03.html#anchor48 CMML] for an example) | * An alternative is to enable the inclusion of a hyperlink for a fragment of time and display in some special way that a hyperlink is present. (see e.g. [http://annodex.net/TR/draft-pfeiffer-cmml-03.html#anchor48 CMML] for an example) | ||
=== Specification language === | |||
A text codec as is required for the specification of captions, subtitles, textual audio description, annotations requires some textual markup language for authoring. A few opinions on the choice of markup language are floating around which are captured here. | |||
* Typically for Web purposes a XML based language - preferrably even a HTML-like language - is preferred. | |||
* If a subset of HTML is selected as a choice for the markup language, parsing and rendering engines of Web browsers can be re-used. | |||
* XML based markup of text codecs however often renders the text specification unreadable. Examples: [http://wiki.xiph.org/index.php/OggKate#Overview_of_the_Kate_bitstream_format Kate] chose a C-like tree that was easy to parse with lex & yacc; [http://www.w3.org/DesignIssues/Notation3 RDF has a N3 notation as a RDF-XML alternative]; [http://en.wikipedia.org/wiki/Subrip srt] and other simple subtitle/caption formats avoid XML] | |||
* When encapsulating text codecs into a binary audio/video file such as Ogg, where compression is everything that counts, a "talkative" XML codec may not be the best choice. | |||
Solution: | |||
* For specification languages, it may be possible to do both, a XML and a non-XML specification (similar to RDF). | |||
* For encapsulation (e.g. into Ogg), it may be best to provide the encapsulation framework in a denser way than XML, but to allow XML fragments to appear as codec pages. | |||
* For decoding into a Web application / browser, there must be a simple way to provide the text codec in a DOM structure. | |||
< [https://wiki.mozilla.org/Accessibility/Video_Accessibility Back to main video accessibility page] | < [https://wiki.mozilla.org/Accessibility/Video_Accessibility Back to main video accessibility page] | ||