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Re: Missing src on img/audio/video and fallback content

From: Ian Hickson <ian@hixie.ch>
Date: Fri, 20 Jun 2008 22:05:49 +0000 (UTC)
To: Philip Jägenstedt <philipj@opera.com>
Cc: HTML WG <public-html@w3.org>
Message-ID: <Pine.LNX.4.62.0806202203350.13974@hixie.dreamhostps.com>
On Fri, 20 Jun 2008, Philip Jägenstedt wrote:
> http://www.w3.org/html/wg/html5/#video
> "If the element has a src attribute: transparent.
> If the element does not have a src attribute: one or more source
> elements, then, transparent."

This is the content model, and shouldn't affect you (it's for authors and 
conformance checkers only).

> "Note: In particular, this content is not fallback content intended to 
> address accessibility concerns. To make video content accessible to the 
> blind, deaf, and those with other physical or cognitive disabilities, 
> authors are expected to provide alternative media streams and/or to 
> embed accessibility aids (such as caption or subtitle tracks) into their 
> media streams."
> That's fine, but what is the fallback when there is no src/source.

The spec says:

# When no video data is available (the element's networkState attribute is 
# either EMPTY, LOADING, or LOADED_METADATA), video elements represent 
# either the image given by the poster attribute, or nothing.
 -- http://www.whatwg.org/specs/web-apps/current-work/#video

...and CSS 2.1 defines the size of a replaced element with no intrinsic 
ratio as being 300x150.

> There are several options, and I'm not sure how others are implementing.
> 1. display nothing (equivialent to css display:none)
> 2. display a 300x150 px transparent box
> 3. display a small icon, red X or similar

Option 2 is the correct option according to the spec at the moment.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Friday, 20 June 2008 22:06:28 UTC

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