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Re: Alt text / alternate image on embed (of QuicktimeVideo)

for

From: Jukka K. Korpela
Date: Apr 17, 2007 10:30AM

On Tue, 17 Apr 2007, Roberts, Vern wrote:

> It's my understanding, in accessibility guidelines, when you're page
> opens, do a check to see if the plugin exists and, if not, furnish a
> link to the place where the plugin can be downloaded.

Some guidelines might say such things, but real accessibility is something
different: it means being prepared to situation where the plugin is not
and will not be available or, more appropriately, _no_ support for some
special kind of media or software is available.

A link to a plugin would be just lip service to accessibility. Finding a
plugin on the net is surely not the key question, especially from the
accessibility point of view.

The correct approach is to make the _content_ accessible in a more robust,
more widely supported format, at least as alternative to some special
format that requires special support.

In theory, you can use the content of an <object> element to specify
fallback for the embedded content. You could even have nested <object>
elements for different levels of fallback. Browsers have spoiled this idea
with their lousy implementations for <object>.

Thus, what remains is that you should include the alternate presentation
or a link to it as normal page content. For example, if you have a
presentation embedded using <object> or <embed>, you could put a short
note about the situation before the embedding area. This means referring
to technicalities, but this cannot be avoided if you want to be
accessible.

For example, you could have text like the following:

<p>The system is illustrated by the animation below. There is also
<a href="explain.html">a textual description</a> of the system,
presenting the same basic features.</p>

(Of course the textual description may have static images, too, in a
well-planned manner.)

--
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/