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Re: Survey ready on Media Text Associations proposal

From: Dick Bulterman <Dick.Bulterman@cwi.nl>
Date: Mon, 08 Mar 2010 21:21:03 +0100
Message-ID: <4B955C2F.9020607@cwi.nl>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
CC: Eric Carlson <eric.carlson@apple.com>, Michael Smith <mike@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
Hi Silvia,

Thanks for the summary. One important point:

> If we were to introduce the SMIL approach, we would require the
> introduction of the following elements:
> * par
> * switch
> * textstream
> 
> instead of introducting:
> * track
> * trackgroup

This is not really true. Because of SMIL's modularization, you would 
only need to take <switch>; <par> and <textstream> have nothing to do 
with the <switch> mechanism itself -- they are also defined in different 
modules. <switch> is a-temporal and does not rely on or require other 
aspects of SMIL timing. (I put these in the example for clarity.>

 From what you describe, <switch> seems to provide all of the 
functionality of <track>/<trackgroup>. It has the advantage that it is 
more general than simple media control: it can be used to structure all 
sorts of underlying content, such as:

...
<switch>
  <div systemLanguage="aa"> ... </div>
  <div systemLanguage="bb"> ... </div>
  <div> ... </div>
</switch>
...
(The last <div> does not have a predicate, so that it will always be 
activated if no earlier element was -- this is equivalent to your 
'enable' example.)

The 'allowReorder' attribute was added at the explicit request of 
another W3C group during last call: someone felt that the strict lexical 
ordering should be relaxed to accommodate a UI-regulated user 
preference. I can dig up the reference, if you like. (It is in a 
separate module, and does not constrain the further use of <switch>.)

Whichever way the group goes, I'd recommend also allowing 
predicate-style activation on statements NOT wrapped in a <switch> or 
<track>/<trackgroup>: this is a very convenient way of handling 
conditional content.

hopefully, food for thought.

-d.
Received on Monday, 8 March 2010 20:21:42 GMT

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