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Timed Media Accessibility: Surveying the terrain

. Timed Media Accessibility: Surveying the terrain. David Singer, with help from the web media team Apple Inc. INTRODUCTION. The 3 legs of good accessibility. Specifications and tutorials Authors Users and user agents. Dream: do better than than TV. Good framework for accessibility

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Timed Media Accessibility: Surveying the terrain

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  1. Timed Media Accessibility: Surveying the terrain David Singer, with help from the web media team Apple Inc.

  2. INTRODUCTION Timed Media Accessibility

  3. The 3 legs of good accessibility • Specifications and tutorials • Authors • Users and user agents Timed Media Accessibility

  4. Dream: do better than than TV • Good framework for accessibility • immediate needs • innovation and increasingly effective future provisions • Use web technologies • Use preferences • Be bright! Timed Media Accessibility

  5. The problem space • Timed accessibility • captions, audio, sign language • Untimed accessibility • transcripts, alternatives Timed Media Accessibility

  6. TIMED ACCESSIBILITY Timed Media Accessibility

  7. Audio • Captions • (Subtitles) • Sign language • Contrast etc. issues Timed Media Accessibility

  8. Video • Audible description of video • Contrast etc. issues • Seizure avoidance (e.g. Epilepsy susceptibility) Timed Media Accessibility

  9. General and Time Management • ‘Slide-flipping’ in parallel with the media • Rate preferences (e.g. normally at 80%) Timed Media Accessibility

  10. UNTIMED ACCESSIBILITY Timed Media Accessibility

  11. Two un-timed challenges • Links to transcripts • Alternative, longdesc and fallback content Timed Media Accessibility

  12. INSIDE OR OUTSIDE THE MEDIA CONTAINER? Timed Media Accessibility

  13. Inside • Burned-in (open) captions • ‘Overlay’ Timed text tracks • Audio narration (description) • Sign-language (video) tracks Timed Media Accessibility

  14. Outside • Captions – scripted or second player Timed Media Accessibility

  15. MEETING NEEDS Timed Media Accessibility

  16. Handling timed accessibility • select the resource which has or can have the provision needed • configure it if it’s an optional feature Timed Media Accessibility

  17. User selection • By preference • By action • Either/Both? Timed Media Accessibility

  18. Hypothesis • ‘Somewhere’ there can be user preferences • Axes: • Captions (subtitles?) • Audio description of video • Sign language • Seizure avoidance, contrast, etc. Timed Media Accessibility

  19. Source selection • Use <source> media query • Allow it to enquire the user’s presentational needs Timed Media Accessibility

  20. Discussion • Simple rules: match prefs-source FAILS if either: • user has a need, and the source says it explicitly does not support it • user does not have a need, and the file is tagged to support it • Second rule is needed so users not wanting (mentioning) a need will skip sources tagged as explicitly for it (e.g. open captions) Timed Media Accessibility

  21. In Tabular Form Timed Media Accessibility

  22. Examples • <source media=“accessibility(captions:yes)” src=“A”/> • <source src=“Z”/> • <source media=“accessibility(captions:yes audio-description:no)” src=“A”/> • <source media=“accessibility(captions:no audio-description:yes)” src=“A”/> • <source src=“Z”/> Timed Media Accessibility

  23. Source Configuration • If source has ‘optional’ features (e.g. a separate text overlay stream for captions) • Let the media engine default enable/disable track the user preferences [out of scope] • Let scripts: • enquire user preference • enquire source provision (‘is there a caption track?’) • affect source configuration (‘turn on caption track’) Timed Media Accessibility

  24. PRESENTATION ISSUES Timed Media Accessibility

  25. Who renders captions? • In media file: media engine • Handled by script and placed into DOM: web engine Timed Media Accessibility

  26. Scripted Accessibility • Enables custom controllers to turn provisions on/off • Sync’ing slides, scripted captions etc. • Cue ranges, where art thou? Timed Media Accessibility

  27. LEVERAGE AND ACTION Timed Media Accessibility

  28. Resources • SMIL for synchronized media • Media queries for presentation needs • Media engine accessibility provisions • Scripting, the DOM and events • Dublin Core and IMS for user preferences? Timed Media Accessibility

  29. Action? • HTML: • revive cue ranges • describe using media queries to select for accessibility (informative) • describe using user preferences to configure for accessibility (informative) • Script access to or control of features of the media • CSS • Media queries for accessibility Timed Media Accessibility

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