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

2. INTRODUCTION 8/28/20152Timed Media Accessibility

3. The 3 legs of good accessibility Specifications and tutorials Authors Users and user agents 8/28/20153Timed 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! 8/28/20154Timed Media Accessibility

5. The problem space Timed accessibility – captions, audio, sign language Untimed accessibility – transcripts, alternatives 8/28/20155Timed Media Accessibility

6. TIMED ACCESSIBILITY 8/28/20156Timed Media Accessibility

7. Audio Captions (Subtitles) Sign language Contrast etc. issues 8/28/20157Timed Media Accessibility

8. Video Audible description of video Contrast etc. issues Seizure avoidance (e.g. Epilepsy susceptibility) 8/28/20158Timed Media Accessibility

9. General and Time Management ‘Slide-flipping’ in parallel with the media Rate preferences (e.g. normally at 80%) 8/28/20159Timed Media Accessibility

10. UNTIMED ACCESSIBILITY 8/28/201510Timed Media Accessibility

11. Two un-timed challenges Links to transcripts Alternative, longdesc and fallback content 8/28/201511Timed Media Accessibility

12. INSIDE OR OUTSIDE THE MEDIA CONTAINER? 8/28/201512Timed Media Accessibility

13. Inside Burned-in (open) captions ‘Overlay’ Timed text tracks Audio narration (description) Sign-language (video) tracks 8/28/201513Timed Media Accessibility

14. Outside Captions – scripted or second player 8/28/201514Timed Media Accessibility

15. MEETING NEEDS 8/28/201515Timed 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 8/28/201516Timed Media Accessibility

17. User selection By preference By action Either/Both? 8/28/201517Timed Media Accessibility

18. Hypothesis ‘Somewhere’ there can be user preferences Axes: – Captions (subtitles?) – Audio description of video – Sign language – Seizure avoidance, contrast, etc. 8/28/201518Timed Media Accessibility

19. Source selection Use media query Allow it to enquire the user’s presentational needs 8/28/201519Timed 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) 8/28/201520Timed Media Accessibility

21. In Tabular Form I want need X satisfied I don’t mention need X targeted for need X √X known not to support need X X√ don’t know about need X √√ 8/28/201521Timed Media Accessibility

22. Examples 8/28/201522Timed 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’) 8/28/201523Timed Media Accessibility

24. PRESENTATION ISSUES 8/28/201524Timed Media Accessibility

25. Who renders captions? In media file: media engine Handled by script and placed into DOM: web engine 8/28/201525Timed Media Accessibility

26. Scripted Accessibility Enables custom controllers to turn provisions on/off Sync’ing slides, scripted captions etc. – Cue ranges, where art thou? 8/28/201526Timed Media Accessibility

27. LEVERAGE AND ACTION 8/28/201527Timed 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? 8/28/201528Timed 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 8/28/201529Timed Media Accessibility