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Re: [media] Moving forward with captions / subtitles

From: Philip Jägenstedt <philipj@opera.com>
Date: Wed, 17 Feb 2010 21:15:53 +0800
To: "Geoff Freed" <geoff_freed@wgbh.org>, "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: "Eric Carlson" <eric.carlson@apple.com>, "HTML Accessibility Task Force" <public-html-a11y@w3.org>
Message-ID: <op.u79wgrqiatwj1d@philip-pc>
On Wed, 17 Feb 2010 21:04:37 +0800, Geoff Freed <geoff_freed@wgbh.org>  

> ________________________________________
> From: Silvia Pfeiffer [silviapfeiffer1@gmail.com]
> Sent: Wednesday, February 17, 2010 6:56 AM
> To: Philip Jägenstedt
> Cc: Geoff Freed; Eric Carlson; HTML Accessibility Task Force
> Subject: Re: [media] Moving forward with captions / subtitles
> On Wed, Feb 17, 2010 at 7:00 PM, Philip Jägenstedt <philipj@opera.com>  
> wrote:
>> On Wed, 17 Feb 2010 15:10:06 +0800, Silvia Pfeiffer
>> <silviapfeiffer1@gmail.com> wrote:
>>> Maybe we have converged?
>> Yes, and for the record this is what I think we agree on:
>> <track> is used to reference an external text track.
> GF:  Agreed.
>> <trackgroup> is used to group several tracks which are mutually  
>> exclusive.
>> Often they will have the same role="", but this isn't necessarily so.
> GF:  So role is *not* a requirement for <trackgroup>, correct?


>> Your example with active changed to enabled:
>> <video src="video.ogv">
>>  <track src="cc.en.srt" srclang="en" role="CC" enabled>
>>  <track src="tad.en.srt" srclang="en" role="TAD">
>>  <trackgroup role="SUB">
>>    <track src="subs.de.srt" srclang="de">
>>    <track src="subs.sv.srt" srclang="sv">
>>    <track src="subs.jp.srt" srclang="jp">
>>  </trackgroup>
>> </video>
>> <track> is a void element (no end tag), if there any reason to think  
>> that it
>> would ever need child elements then now is the time to give it an end  
>> tag.
> GF:  I can't think of a reason today, but there may be reasons in the  
> future.  Is it a big deal to require an end tag?  If not, I think we  
> should require one now.

I'm not a fan of void elements and wouldn't mind <track> having an  
end-tag. The case that might happen is that <track> is used for external  
additional audio/video tracks (e.g. sign language overlays) and we need  
<source> to provide fallback because we don't have a baseline audio/video  
codec (just like for <audio>/<video>, not in the sense that we've been  
using <source> in this discussion).

> Re enabling/disabling:  in the example above, the CC track is enabled by  
> default while the others are enabled at the user's discretion.  Would it  
> not be more logical, and more consistent with other attribute  
> structures, to use markup to make this explicit?  That would require the  
> use of enable="on" or enable="off" on each track.  Hmmm.  This is akin  
> to SMIL's systemCaptions="on/off".  And that brings up the SMIL argument  
> again.

Boolean attributes are a pretty standard thing in HTML, where the only way  
to express false is to not have the attribute at all. This is consistent  
with e.g. the attributes "selected", "autoplay", etc.

Philip Jägenstedt
Core Developer
Opera Software
Received on Wednesday, 17 February 2010 13:16:33 UTC

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