W3C home > Mailing lists > Public > public-html@w3.org > September 2008

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

From: Robert J Burns <rob@robburns.com>
Date: Tue, 9 Sep 2008 20:11:07 +0200
Cc: David Poehlman <david.poehlman@handsontechnologeyes.com>, Henri Sivonen <hsivonen@iki.fi>, Matt Morgan-May <mattmay@adobe.com>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Message-Id: <A373267A-44A0-4008-9C33-D258E93C6B7D@robburns.com>
To: Leif Halvard Silli <lhs@malform.no>

Hi Leif,

On Sep 9, 2008, at 7:31 PM, Leif Halvard Silli wrote:

>
> David Poehlman 2008-09-09 17.55:
>
>> Barring this, I am not certain that *@longdesc* is appropriate for  
>> either since replacement/substitution is not *description*.  I fear  
>> we vear from the value of @longdesc if we use it in a manner which  
>> provides substitution. an @longdesc of a video would be something  
>> achin to textual audio description.
>
>
> I complained that Henri took <video> to mean commercial video. But I  
> think here you mix the name "longdesc" with "long description".  
> "longdesc" is a bad name for something which is meant to represent   
> "a long or complex alt".

As I argued before, I think longdesc is currently used in three  
different ways: 1) as you say as "a long or complex alt"; 2) also as a  
supplementary descriptive text equivalent, when other alt text is  
already available from the alt attribute; and 3) even at times in the  
same way as describedby is intended to be used to explicitly associate  
an image with the surrounding text that describes it.

>
>
>> A transcript or a manuscript is the full text or in the case of a  
>> transcript, perhaps an annotated full text of what is said in the  
>> <video> which provide proper substitution.  In any case, even what  
>> is in the @longdesc in this case is replacement and description  
>> probably needs to confine its self to describing the activity and  
>> the surroundings etcettera without including the content.  We'd get  
>> the names of the characters, the colors and sizes, what they are  
>> dressed like, where the event is being held etc.
>
> This is not in line with what @longdesc is in HTML 4. In fact, if  
> anything, it would have been the @alt which contained what you say  
> the @longdesc resource should contain. Consider the  example code in  
> the HTML 4 specification:
>
> <BODY>
> <P>
> <IMG src="sitemap.gif"
>     alt="HP Labs Site Map"
>     longdesc="sitemap.html">
> </BODY>

This example underscores the 2nd use of longdesc. In other words this  
is not a long or complex alt text, but rather a text equivalent that  
is supplementary to the alt text and descriptive. I think HTML5 should  
really understand these subtle distinctions and try to disentangle  
these uses. For example 2 and 3 are needed for all embedded media.  
However, 1 (long or complex alt text) is only needed for images that  
are void (IMG and EMBED). I think the second use is often better  
handled through adding support for exposing the media files immanent  
metadata[2] because such description is typically independent of the  
circumstances of embedding in the document (unlike alt text). However,  
there may still be a need for such a separate URI ref valued attribute  
for descriptions (for example when a user doesn't want to have to  
download an entire video file over HTTP or other protocols just to get  
the text description immanent to the file).

Take care,
Rob

[1]: <http://lists.w3.org/Archives/Public/public-html/2008Sep/0263.html>
[2]: <http://esw.w3.org/topic/HTML/UANormAndDOMForMediaPropeties>
Received on Tuesday, 9 September 2008 18:12:36 UTC

This archive was generated by hypermail 2.3.1 : Monday, 29 September 2014 09:38:58 UTC