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Accessibility/Video a11y Study08: Difference between revisions
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Revision as of 08:38, 5 February 2009
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=== 3. Dealing with Out-of-band Time-aligned Text === | === 3. Dealing with Out-of-band Time-aligned Text === | ||
In the accessibility requirements document and the OggText proposal, a large number of categories of time-aligned text that have been seen in online video and audio applications, were identified: | In the [https://wiki.mozilla.org/Accessibility/Video_a11y_requirements accessibility requirements document; and the [http://wiki.xiph.org/index.php/OggText OggText proposal], a large number of categories of time-aligned text that have been seen in online video and audio applications, were identified: | ||
* CC: closed captions (for the deaf) | * CC: closed captions (for the deaf) | ||
* SUB: subtitles | * SUB: subtitles | ||
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The ability to dynamically associate a time-aligned text file with an audio or video file at the moment of playback is very powerful. It has allowed the creation of a whole community of subtitling fans, the fansubbers, to be created which provides accessibility to almost all movies and feature files. | The ability to dynamically associate a time-aligned text file with an audio or video file at the moment of playback is very powerful. It has allowed the creation of a whole community of subtitling fans, the fansubbers, to be created which provides accessibility to almost all movies and feature files. | ||
To provide such a functionality inside a Web browser, it is necessary to specify out-of-band time-aligned text files with the video. A proposal has been made to the WHATWG as a result of the study to support a "text" sub-element of the "video" and "audio" elements that allows the specification of such an external text file. There are a some details at this blog post. An example looks as follows: | To provide such a functionality inside a Web browser, it is necessary to specify out-of-band time-aligned text files with the video. A proposal has been made to the WHATWG as a result of the study to support a "text" sub-element of the "video" and "audio" elements that allows the specification of such an external text file. There are a some details at [http://blog.gingertech.net/2008/12/12/attaching-subtitles-to-html5-video/ this blog post]. An example looks as follows: | ||
<pre> | <pre> | ||
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How this will actually work is as yet unclear. One approach is to render the out-of-band text files as HTML straight into the DOM of the current Web page. This raises security issues. Another approach is to render it into a kind of iframe. Also, SVG has a "text" element that serves a similar purpose, so the specification could be aligned with that. | How this will actually work is as yet unclear. One approach is to render the out-of-band text files as HTML straight into the DOM of the current Web page. This raises security issues. Another approach is to render it into a kind of iframe. Also, SVG has a "text" element that serves a similar purpose, so the specification could be aligned with that. | ||
There are experimental implementations in javascript of this proposal, one for srt through Wikipedia and one for dfxp through the W3C TimedText working group. Both map the respective out-of-band file into the DOM of the current Web page. | There are experimental implementations in javascript of this proposal, one for srt through [http://metavid.org/w/extensions/MetavidWiki/skins/mv_embed/example_usage/sample_timed_text.php Wikipedia] and one for dfxp through the [http://www.w3.org/2008/12/dfxp-testsuite/web-framework/START.html W3C TimedText working group]. Both map the respective out-of-band file into the DOM of the current Web page. | ||
Further analysis, experiments, and a proper specification of this new element are required. | Further analysis, experiments, and a proper specification of this new element are required. | ||
'''Recommendation 3:''' Develop a detailed specification and experimental implementations of how to handle out-of-band time-aligned text files for the "video" and "audio" elements of HTML5. In the WHATWG group, it was suggested that a first step may be a mapping of typical file formats to HTML (and CSS), which should include at minimum sub, srt, lrc, trs and dfxp. | '''Recommendation 3:''' Develop a detailed specification and experimental implementations of how to handle out-of-band time-aligned text files for the "video" and "audio" elements of HTML5. In the WHATWG group, it was suggested that a first step may be a mapping of typical file formats to HTML (and CSS), which should include at minimum sub, srt, lrc, trs and dfxp. | ||
=== 4. Developing a comprehensive Time-aligned Text Format === | === 4. Developing a comprehensive Time-aligned Text Format === | ||