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re-rewrite Action-503 - 2.9.2 Time-Based Media Load-only

From: Jim Allan <jimallan@tsbvi.edu>
Date: Wed, 9 Mar 2011 17:33:44 -0600
Message-ID: <AANLkTinM2uk2z67hh7SCZPbbq3di6o=qPtaYPsTRXmyp@mail.gmail.com>
To: WAI-ua <w3c-wai-ua@w3.org>
2.9.2 Time-Based Media Load-Only: The user can override the play on
load of recognized time-based media content such that the content is not played
until explicit user request. (Level A)

Intent
As an opt-in user setting, autoplay for media is off/paused, until the
user activates 'play'. The user agent provides a global control that
sets a state equivalent to "paused waiting for user interaction" for
all recognized media when a page loads.This prevents media from
playing without explicit request from the user. This helps users who
need to avoid signals that may trigger seizures, users who are easily
distracted, and users who have difficulty interacting with the
controls provided for playing media. The user agent provides a visual
or auditory (as appropriate) indicator that the video is in paused
state and needs user interaction to start.

There may times when media doesn't have a native control in the page.
That is, the media is not in the actual document, but rather has
simply been created with document.createElement('audio'). Here, the
user agent does not recognize that the media exists. The user agent
cannot give a visual indication by default, as it wouldn't be clear
where that indication should appear in the page. At that stage, it
will be up to the author to provide the controls See WCAG in resources
below.

Examples
1. Stuart, a screen reader user, opens a page with an audio element
that starts playing immediately. He cannot hear the screen reader
because of the noise from the audio element, and must search through
the page to find the 'noisy' element to pause or turn it off. Once
the screen reader is the sole source of audio the he can read the page
and determine if the audio is important and choose to play it.

2. Using similar techniques that are used for pop-up blockers, the
user agent checks to see if the play() request was from user
interaction or a background script. If  it isn't from direct user
interaction, the user agent could ask the user to explicitly allow the
media to play, perhaps remembering the choice for the site.

3. Playback of a <video> or <audio> element can only be triggered in
response to a user gesture on a touch screen device with no keyboard
(like pop-up blockers).

4. The user agent provides a global control that calls "paused for
user interaction" for all media when a page loads.

Resources
HTML5 4.8.10.8 Playing the media resource
(http://dev.w3.org/html5/spec/Overview.html#playing-the-media-resource)
WCAG 2.0 - 1.4.2 Audio Control
http://www.w3.org/TR/WCAG20/#visual-audio-contrast



-- 
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 Wednesday, 9 March 2011 23:34:18 GMT

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