[whatwg] Alt attribute for <video> and <audio>

Philip Jägenstedt philipj at opera.com
Wed Aug 12 04:26:26 PDT 2009

On Wed, 12 Aug 2009 12:52:38 +0200, Remco <remco47 at gmail.com> wrote:

> On Wed, Aug 12, 2009 at 10:57 AM, Philip Jägenstedt<philipj at opera.com>  
> wrote:
>> Before suggesting any changes to the <source> element, make sure you  
>> have
>> read
>> http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#concept-media-load-algorithm
>> Put simply, the handling of <source> is already quite complex,  
>> overloading
>> it with completely different meanings is not a good idea. <video> won't
>> handle "text/html" as a source, but if you want different media files  
>> for
>> different audiences I suggest experimenting with <source media>.
> <source media> doesn't do anything useful for my case. It can't load
> textual data. Also, if the resources are unavailable, there will be
> nothing to see, since all resources are off-page. It also doesn't work
> for iframe, object, embed or img.
> Is it really the idea that the only way you're going to have
> alternative textual content, is to Build It Yourself? You have to
> abuse <details> or a hidden <div> with some Javascript to build a
> construction that has alternative content in case the
> video/audio/iframe/object/embed is not available or desirable. If you
> want it to be semantically accessible, you even have to build another
> layer on top of that, in the form of ARIA attributes.

No, in the long term we want native captions/subtitle support in the  
browsers. See  
and maybe http://lists.w3.org/Archives/Public/public-html/2009Aug/0439.html

> Nobody will do that. Even the <source> solution is harder, maybe too
> hard, to use than the alt="" solution. It requires authors to create
> additional elements or pages to house the alternative content. Since
> accessibility is often an afterthought, about the most an author will
> be willing to do, is filling in an alt attribute.

What do you suggest a browser do with the alt attribute? The resource  
selection algorithm never ends until a suitable source is found, so when  
should the alt text be displayed? By requiring anything at all, browsers  
can't do things like display a box with a direct download link, suggestion  
to install a specific codec, etc. If nothing at all is required of user  
agents for the alt attribute, then I have no opinion (but then I expect no  
one would use it either).

Philip Jägenstedt
Core Developer
Opera Software

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