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Re: Is longdesc a good solution? (was: Acessibility of <audio> and <video>)

From: Leif Halvard Silli <lhs@malform.no>
Date: Sun, 07 Sep 2008 21:31:16 +0200
Message-ID: <48C42C04.8070202@malform.no>
To: Henri Sivonen <hsivonen@iki.fi>
CC: David Poehlman <david.poehlman@handsontechnologeyes.com>, John Foliot <foliot@wats.ca>, 'James Craig' <jcraig@apple.com>, 'Lachlan Hunt' <lachlan.hunt@lachy.id.au>, public-html@w3.org, 'W3C WAI-XTECH' <wai-xtech@w3.org>

Henri Sivonen 2008-09-07 14.54:

> On Sep 7, 2008, at 14:56, David Poehlman wrote:
>
>> and what is the "something else"?
>
> Oops. I misunderstood which part of my message was being referred to.
>
> "something else" in the last sentence could be:
> * Merely juxtaposed text that restates whatever it is the image
> illustrates.
> * Juxtaposed text associated with aria-describedby.

> * Link to a different page phrased as a "more information" link for all
> audiences as opposed to a [D]-link.
> * <object> element with HTML fallback content.

1+ for mentioning <object>.

Draft: Both @longdesc and the <object/> fallback should represent 
a "long @alt text". Thus I assume you agree that the 
How-to-use-the-@alt section of the draft needs to be extended with 
info about when to use @longdesc and/or <object/> instead of @alt.

<video>: Would you propose the use of <object> instead of <video> 
when HTML fallback for videos is wanted as well? (The current 
discussion started with a proposal to add @longdesc to <video>.)

<img>: The reasons to let <object/> replace <img> should roughly 
be identical to the reasons for adding @longdesc, namely:
* impossible to represent the equivalent fallback in the @alt,
* not fitting to textually *duplicate* the message of the graphic 
in the juxtaposing text of the <img>.

Juxtaposed text: Can juxtaposing replace the use of @longdesc or 
<object/>? That question in my view falls into the same category 
as the question about whether @alt can be dropped when @alt text 
is "unavailable". Currently, the draft advices against ever 
dropping the @alt, but says one may drop it still if the 
surrounding text fulfills som criterias (use of heading etc).

Consequently, I don't think juxtaposing text ever should count as 
replacement for @longdesc or <object/>.

For example, consider that an <img> has a so complex - or 
condensed - graphical message, that a description in the 
juxtaposed text is needed. Would that text then be equal to a 
@longdesc fallback?  I don't think so. A short table might require 
a long description. But that doesn't make the long description a 
fallback for the table.
-- 
leif halvard silli
Received on Sunday, 7 September 2008 19:32:18 UTC

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