Download presentation
Presentation is loading. Please wait.
Published bySteven Rice Modified over 9 years ago
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
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.