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Re: [Bug 5758] insufficient accessibility fallback for <audio> or <video>

From: Joe D Williams <joedwil@earthlink.net>
Date: Sun, 14 Mar 2010 08:09:59 -0700
Message-ID: <28526C61D99C41EBA6679D059DE87393@joe1446a4150a8>
To: <public-html@w3.org>
> accessibility fallback

I think it is unfortunate that both of these words are used together 
here. Accessibitlity is what we want when the thing is running. 
Fallback is what we want when the thing won't run.

<video> should have two layers of "fallback". The first fallbeck steps 
happen when the UA chooses between one of several resources the author 
has named. This step of fallback allows the author to specify multiple 
resources and the UA tries the choices in sequence until a usable 
resource is found. The next step of fallback is what happens when the 
<video> element is not recognized and the UA produces the author's 
alternate content.

This follows the model set by <object> and could result in use of the 
following construction:

.<video autoplay controls>
 <source src="tgif.vid">
 <source src="lgif.zvid">
  <p><a href="tgif.vid">Download the video file.from this 

In this example if the UA did not recognize the <video> element then 
the html "fallback" content enclosed in <p> and <a> element would be 
shown. This operation is more than just a specification for <video>, 
<audio>, or <object> but just intrinsically how the web UA should 
work: Skip elements that are not in the vocabulary. So, here, an old 
UA would just naturally skip <video ... >, <source ... >, and <source 
... > and end up showing the html link according to the <p> and <a> 
style, although the UA will probalbly also apply CSS specified for 

In this example if the UA recognizes <video ...> but does not 
recognize .vid content then the the potential fallback video content 
.zvid will be tried. If still no go, then the html "fallback" content 
enclosed in <p> element would be shown according to the <video>, <p>, 
and <<a> styles.

Again, that is basically the model for <object> where the contained 
html is shown if the UA cannot produce the <object> content. This is a 
well-proven and mostly reliable technique.

So, accessibility is not "fallback" but appears to the author and 
client as something built-in to the <video> object and closely linked 
to the content that is actually being played.

Thanks to All and Best Regards,

----- Original Message ----- 
From: <bugzilla@wiggum.w3.org>
To: <public-html@w3.org>
Sent: Sunday, March 14, 2010 6:32 AM
Subject: [Bug 5758] insufficient accessibility fallback for <audio> or 

> http://www.w3.org/Bugs/Public/show_bug.cgi?id=5758
> Michael(tm) Smith <mike@w3.org> changed:
>           What    |Removed                     |Added
> ----------------------------------------------------------------------------
>           Keywords|                            |TrackerIssue
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Received on Sunday, 14 March 2010 15:10:41 UTC

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