- From: Jim Allan <jimallan@tsbvi.edu>
- Date: Tue, 4 May 2010 14:16:24 -0500
- To: "'Jim Allan'" <jimallan@tsbvi.edu>, "'HTML Accessibility Task Force'" <public-html-a11y@w3.org>
- Cc: "'WAI-UA list'" <w3c-wai-ua@w3.org>, "'John Foliot'" <jfoliot@stanford.edu>
Just a slight title change to better reflect the scope. And a shout out to Mark Hakkinen for collaborating on this document. > -----Original Message----- > From: Jim Allan [mailto:jimallan@tsbvi.edu] > Sent: Tuesday, May 04, 2010 1:51 PM > To: 'HTML Accessibility Task Force' > Cc: 'WAI-UA list'; 'John Foliot' > Subject: UAAG 2.0 guidelines for video > > The UAAG Guidelines[1] in their present form are organized by basic > principles that, when applied as a whole, provide guidance in ensuring > that a user agent and the (accessible) content it renders, and provides > interaction with, is accessible. As such, specific guidelines that > apply to multimedia, or as we call it, time-based media, rendering and > interaction are found across several of the principles. This document > is a first pass at extracting the guidelines of relevance to the media > accessibility subgroup. Feedback on these guidelines, as well as the > overall UAAG document is welcome. The UAAG Implementation document [2] > is also available for review. > > > PRINCIPLE 2. Facilitate programmatic access > > 2.1.1 Platform Accessibility Architecture: Support an platform > accessibility architecture relevant to the operating environment. > (Level A) > > 2.1.2 Name, Role, State, Value, Description: 2.1.2 Name, Role, State, > Value, Description: For all user interface components including the > user interface, rendered content, and alternative content, make > available the name, role, state, value, and description via an platform > accessibility architecture. (Level A) > > 2.1.3 Accessible Alternative: If a feature is not supported by the > accessibility architecture(s), provide an equivalent feature that does > support the accessibility architecture(s). Document the equivalent > feature in the conformance claim. (Level A) > > 2.1.4 Programmatic Availability of DOMs: If the user agent implements > one or more DOMs, they must be made programmatically available to > assistive technologies. (Level A) > > 2.1.5 Write Access: If the user can modify the state or value of a > piece of content through the user interface (e.g., by checking a box or > editing a text area), the same degree of write access is available > programmatically. (Level A) > > 2.1.6 Properties: If any of the following properties are supported by > the accessibility platform architecture, make the properties available > to the accessibility platform architecture: (Level A) > > (a) the bounding dimensions and coordinates of rendered graphical > objects > (b) font family of text > (c) font size of text > (d) foreground color of text > (e) background color of text. > (f) change state/value notifications > > 2.1.7 Timely Communication: For APIs (for non-web-based user agents) > implemented to satisfy the requirements of this document, ensure that > programmatic exchanges proceed at a rate such that users do not > perceive a delay. (Level A). > > PRINCIPLE 3: Perceivable - The user interface and rendered content must > be presented to users in ways they can perceive > > 3.1.1 Identify Presence of Alternative Content The user has the ability > to have indicators rendered along with rendered elements that have > alternative content (e.g. visual icons rendered in proximity of content > which has short text alternatives, long descriptions, or captions). In > cases where the alternative content has different dimensions than the > original content, the user has the option to specify how the > layout/reflow of the document should be handled. (Level A). > > 3.1.2 Configurable Default Rendering: The user has a global option to > specify which types of alternative content by default and, in cases > where the alternative content has different dimensions than the > original content, how the layout/reflow of the document should be > handled. (Level A) > > 3.1.3 Browse and Render: The user can browse the alternatives, switch > between them, and render them according to the following (Level A): > > 1. synchronized alternatives for time-based media (e.g., captions, > audio descriptions, sign language) can be rendered at the same time as > their associated audio tracks and visual tracks, and > 2. non-synchronized alternatives (e.g., short text alternatives, > long descriptions) can be rendered as replacements for the original > rendered content. > > 3.1.4 Rendering Alternative (Enhanced): Provide the user with the > global option to configure a cascade of types of alternatives to render > by default, in case a preferred type is unavailable. If the alternative > content has a different height or width, then the user agent will > reflow the viewport. (Level AA) > > 3.6.1 Configure Text: The user can globally set the following > characteristics of visually rendered text content, overriding any > specified by the author or user agent defaults (Level A): > > * (a) text scale (i.e., the general size of text) , > * (b) font family, and > * (c) text color (i.e., foreground and background). > > PRINCIPLE 4. Ensure that the user interface is operable > > 4.1.1 Keyboard Operation: All functionality can be operated via the > keyboard using sequential or direct keyboard commands that do not > require specific timings for individual keystrokes, except where the > underlying function requires input that depends on the path of the > user's movement and not just the endpoints (e.g., free hand drawing). > This does not forbid and should not discourage providing mouse input or > other input methods in addition to keyboard operation. (Level A) > > 4.9.2 Time-Based Media Load-Only: The user has the option to load time- > based media content @@DEFINE@@ such that the first frame is displayed > (if video), but the content is not played until explicit user request. > (Level A) > > 4.9.5 Playback Rate Adjustment for Prerecorded Content: The user can > adjust the playback rate of prerecorded time-based media content, such > that all of the following are true (Level A): > > * The user can adjust the playback rate of the time-based media > tracks to between 50% and 250% of real time. > * Speech whose playback rate has been adjusted by the user > maintains pitch in order to limit degradation of the speech quality. > * Audio and video tracks remain synchronized across this required > range of playback rates. > * The user agent provides a function that resets the playback rate > to normal (100%). > > 4.9.6 Stop/Pause/Resume Multimedia: The user can stop, pause, and > resume rendered audio and animation content (including video and > animated images) that last three or more seconds at their default > playback rate. (Level A) > > 4.9.6 Navigate Multimedia: The user can navigate along the timebase > using a continuous scale, and by relative time units within rendered > audio and animations (including video and animated images) that last > three or more seconds at their default playback rate. (Level A) > > 4.9.7 Semantic Navigation of Time-Based Media. The user can navigate by > semantic structure within the time-based media, such as by chapters or > scenes, if present in the media (AA). > > 4.9.8 Track Enable/Disable of Time-Based Media. During time-based media > playback, the user can determine which tracks are available and select > or deselect tracks. These selections may override global default > settings for captions, audio descriptions, etc. > > > > 4.9.9 Sizing Playback Viewport: User has the ability to adjust the size > of the time-based media up to the full height or width of the > containing viewport, with the ability to preserve aspect ratio and to > adjust the size of the playback viewport to avoid cropping, within the > scaling limitations imposed by the media itself. (Level AA) > > 4.9.10 Scale and position alternative media tracks. User has ability to > scale and position alternative media tracks independent of base video. > (Level AAA) > > 4.9.11 Adjust Playback Contrast and Brightness. User has ability to > control the contrast and brightness of the content within the playback > viewport. > > 1. http://www.w3.org/WAI/UA/2010/ED-UAAG20-20100430/ > 2. http://www.w3.org/WAI/UA/2010/ED-IMPLEMENTING-UAAG20-20100430/ > > Jim Allan, Accessibility Coordinator & Webmaster > Texas School for the Blind and Visually Impaired > 1100 W. 45th St., Austin, Texas 78756 > voice 512.206.9315 fax: 512.206.9264 http://www.tsbvi.edu/ > "We shape our tools and thereafter our tools shape us." McLuhan, 1964 >
Received on Tuesday, 4 May 2010 19:12:52 UTC