[Bug 10642] No alternative text description for video key frame (poster)


--- Comment #74 from Silvia Pfeiffer <silviapfeiffer1@gmail.com> 2010-11-14 14:37:03 UTC ---
(In reply to comment #73)
> (In reply to comment #72)
> > Yes, but it is also impossible to render two different alternative texts for a
> > single element unit. It's not like the <video> element and the poster are two
> > separate elements - they are a single entity that is presented to sighted users
> > as a single object on screen. How should two different alternative texts for a
> > single object even be rendered?
> Hi Silvia,
> The User Agent Accessibility Guidelines may be helpful:
> Guideline 3.1 Provide access to alternative content.
> 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)
> http://www.w3.org/TR/UAAG20/#principle-perceivable

Hi Laura,

We are talking about two non-synchronized short text alternatives to a single
element that consists of a single image representation which is sourced
potentially from two different Web resources, but maybe not. I can't see where
such a situation is described in your quoted text nor can I think of a useful
way to render the two text alternatives for the one video through a screen
reader when tabbing onto the video. I don't think that situation has occurred
in other elements before.

Just to make sure: I totally believe we need to have multiple synchronized
alternatives for different purposes. But that is not the issue under

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Received on Sunday, 14 November 2010 14:37:07 UTC