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RE: [media] Moving forward with captions / subtitles

From: Geoff Freed <geoff_freed@wgbh.org>
Date: Sun, 14 Feb 2010 09:40:23 -0500
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
CC: Philip Jägenstedt <philipj@opera.com>, Eric Carlson <eric.carlson@apple.com>, HTML Accessibility Task Force <public-html-a11y@w3.org>
Message-ID: <B3526F4AC3C3C64388BF661A8B2112A75EE20ABB86@EXCHCCR.wgbh.org>


From: Silvia Pfeiffer [silviapfeiffer1@gmail.com]
Sent: Sunday, February 14, 2010 9:26 AM
To: Geoff Freed
Cc: Philip Jägenstedt; Eric Carlson; HTML Accessibility Task Force
Subject: Re: [media] Moving forward with captions / subtitles

Hi Geoff,

On Mon, Feb 15, 2010 at 12:18 AM, Geoff Freed <geoff_freed@wgbh.org> wrote:
> Comments preceded by GF.
> GF:  I would prefer that we allow multiple tracks to be active simultaneously, regardless of language or role.  There are already
> real use cases today where various combinations of subtitles, captions and audio descriptions are simultaneously active;
> production agencies in the US are offering multi-track accessibility as a service so we need to support this.

I agree.

> Also, I wouldn't be so quick to say that all tracks of the same role should be mutually exclusive.  Most of the time, only one track
> per role *will* be all that is necessary.  However, there may be cases where, for example, someone will want to use a caption
> track and a subtitle track simultaneously in order to learn a new language.  Or have an audio track of descriptions running
> alongside directorial commentary.

Indeed with the current spec that we have at
http://www.w3.org/WAI/PF/HTML/wiki/Media_TextAssociations, caption and
subtitle track can be shown in parallel. All we are excluding is
showing multiple caption tracks at the same time. Or multiple textual
audio descriptions. Or multiple subtitles. The latter one is the only
case where it may make sense to have multiple tracks in parallel. 

GF:  Sorry, I didn't make myself very clear-- I *am* advocating for the simultaneous display of multiple of tracks with the same role (captions and subtitles are different roles; my apologies for using that in my example).  While multiple subtitle tracks is an obvious case today, I don't want to rule out other cases with other roles in the future.

the current state of the spec that would need to be done through
JavaScript. But if we introduced a @src attribute on a <track> element
as discussed earlier in the thread, without a subhierarchy of <source>
elements, we could even make this possible.

Are people for/against introducing the @src attribute on <track> in
http://www.w3.org/WAI/PF/HTML/wiki/Media_TextAssociations ?

GF:  It definitely sounds like we should consider this option.

> I don't know exactly what it would take to allow multiple roles to be active in this way, but we shouldn't abandon the idea so soon.
> Tthe idea of having the author solve the problem through the use of scripts has been floated, but is that a good solution?  If the
> goal of <video> and related elements/attributes is to make it easier for authors to integrate multimedia-- and *accessible*
> multimedia, at that-- into the Web, does pushing multi-track-role capability to scripts contribute to that goal?

I agree and the current spec provides support for the parallel display
of different roles.

I'd actually say that since a parallel display of tracks with
different roles is already possible when they come through a
encasulated media file (e.g. through MP4), it only makes sense to also
allow this with externally referenced files. 

GF:  Absolutely.  I think we're in violent agreement here!

Interestingly, MP4 also
has a notion of grouping that is similar to the one we have introduced
through the <track> element with the @role attribute. I am currently
working with Xiph people to see if something similar could be
introduced in Ogg.

Received on Sunday, 14 February 2010 14:41:13 UTC

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