Re: TTML after March

As David alludes, the whole business of TTML dependency on XSL-FO is based
on a poor reading of the spec. The only use made (and intended to be made)
of XSL-FO was for the purpose of defining formatting semantics without
having to do so directly in TTML. Further, for the most part, the style
properties adopted in TTML are properties which XSL-FO borrows from CSS. In
doing this, TTML does not make use of the CSS Box Model, but instead makes
use of the XSL-FO Area Model, which are distinct, but similar models (and
conceptual vocabularies) for describing formatting and presentation.

It is true, however, that TTML explicitly avoided the use of CSS grammars
(except for property value grammars for those properties adopted from CSS
via XSL-FO). The rationale for this choice was to avoid having to have two
different parsers: an XML parser and a CSS parser.

If there were sufficient industry interest in doing so, and, in particular,
if this would produce a positive impact on TTML take-up, then it would be
relatively straightforward to define a CSS binding for TTML that employs
CSS for style association rather than the existing mechanism defined in
TTML.

G.

On Mon, Jan 16, 2012 at 12:04 AM, Glenn Adams <gadams@xfsi.com> wrote:

>
>
> ---------- Forwarded message ----------
> From: David Singer <singer@apple.com>
> Date: Wed, Jan 11, 2012 at 5:37 PM
> Subject: Re: TTML after March
> To: Philippe Le Hegaret <plh@w3.org>
> Cc: public-tt <public-tt@w3.org>
>
>
> I'd like to move to a CG for a while.  I think that there is some work to
> be done; the one that comes immediately to mind is documenting the profile
> of TTML as she is used.  A full-on WG may not be needed.
>
>
> On Jan 11, 2012, at 13:40 , Philippe Le Hegaret wrote:
>
> > The charter of the TTML Working Group will expire at the end of March
> > 2012 [1] (it was extended for one year in 2011). I'm curious about the
> > thoughts from individuals here about what to do, if anything, beyond the
> > end of March.
> >
> > For example, SMPTE did some extensions to SMPTE-TT back in 2010. Should
> > we look at those and fold them back in the specification?
>
> maybe…
>
> >
> > Dynamic flow was removed from the specification due to lack of
> > implementation experience. Should it be reconsidered?
> >
> > Should we switch from XSL FO to CSS?
>
> or document how CSS styling can be used.  People think that XSL is
> intrinsic, and I am not sure the group agrees.
>
> >
> > Should we do a profile of TTML as well and retaining features that are
> > the most deployed?
>
> Yes!  This is urgent!
>
> >
> > Or should the group just declare victory and go home?
> >
> > Thank you,
> >
> > Philippe
> >
> > [1] http://www.w3.org/2008/01/timed-text-wg.html
> > [2]
> >
> http://www.w3.org/TR/2010/CR-ttaf1-dfxp-20100223/#style-attribute-dynamicFlow
> >
> > PS: if someone wants to ask the Timed Text Community Group for feedback
> > on this matter as well, feel free to forward this message. Input is
> > welcome!
> >
> >
>
> David Singer
> Multimedia and Software Standards, Apple Inc.
>
>
>
>