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Issue 517 recap

From: Al Gilman <asgilman@iamdigex.net>
Date: Thu, 12 Jul 2001 13:22:06 -0400
Message-Id: <200107121711.NAA2268925@smtp2.mail.iamworld.net>
To: w3c-wai-ua@w3.org
At 03:24 PM 2001-07-10 , Jon Gunderson wrote:
>    8.Issue 517: Need clarification of issue (Al Gilman or SVG people)
>

AG::

I can't replace the SVG group or make any definitive statements.  So let's
make
this Al and SVG people, not 'or.'  But here is my impression of what is going
on and a possible next step toward resolving this one.

I think that this may involve a miscommunication about the granularity of
content scopes that the required control of play is supposed to apply to.

I suspect that the SVG group interpreted 'elements' as XML elements such as
'g'
elements which take on the role of dependend time containers in an animated
SVG.  It is in this context that they objected.

I think the UA working group meant that these controls should be available for
separately playable media objects, not for every 'g' element involved in the
construction of an SVG animation, even if in the timing structure that element
is a time container.  It may well be that there are no independently playable
components below the level of the "root time container" in this case.  It
would
seem to be a misunderstanding of the scopes of content over which these
controls would be exercised as a unit.  See my remarks on issue 516 -- that
may
be clearer.  Subissue a.

In 2.3 I believe we set the precedent that user on/off control was only
required for the substructures that actually play a role in the content
control
functions of the format.  Each chunk of conditional content that is suject to
one condition is treated as a whole.  Finer subdivisions unconditionally
included in that substructure are not items to be separately, interactively
controlled under 2.3.

In 4.4 and 4.5 I think that what the user needs to have this control over are
at least the independently playable [multi-] media presentations as grouped
into synchronous presentations by the author, with the possible extension to
independently playable substructures that may be isolated pursuant to 2.3.
The
latter takes care of playing just one audio track, or just one video track in
isolation as a relatively extreme but feasible recourse to try to understand a
SMIL presentation when operating under duress of some sort or another.

I think we should informally approach the SVG people with this perception of a
possible miscommunication, and if this is in fact an important clarification,
then we take a fresh look at do we perhaps have some feasible path to a
mutually agreeable resolution.

Al

PS:  Ian has repeatedly asked, what is the technicality that the UA group
didn't understand.

I don't really think it is a 'technicality,' quite.  It is more like a
significant difference in performance.  In SMIL proper, one has a relatively
small number of relatively strongly-encapsulated constituents.  Many of these
things it makes sense to play individually.  In an SVG animation, although it
uses the same language constructs to build its time relationships, one finds a
relatively large number of relatively weakly-encapsulated constituents.  One
doesn't that much know where in the 'g' tree to stop.  And 'playing' just one
makes vanishingly little sense.  We had thought a lot about the SMIL case and
hadn't thought much about the animated SVG case.  So what we said can be
interpreted (and they did) as an overly-demanding descent into the bowels
of an
animation to perform play actions that don't come naturally.  That isn't
really
what we meant.
Received on Thursday, 12 July 2001 13:11:48 GMT

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