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RE: [SVGMobile12] STZLC3-4 animation of xlink:href of a media

From: Doug Schepers <doug@schepers.cc>
Date: Fri, 3 Mar 2006 17:22:12 +0100
To: "'Jean-Claude Dufourd'" <jcdufourd@gmail.com>, <www-svg@w3.org>
Message-Id: <20060303162213.C879560C0B@filch.dreamhost.com>

Hi, Jean-Claude-

We agree that this is a serious issue, and since it is outside the scope of
the SVG WG to define this behavior, we will coordinate with the SYMM WG to
address these and related issues. In the meantime, this should not affect
the ability to conformantly implement SVGTiny1.2, since we normatively refer
to SMIL2.1 for this range of behaviors, and any changes to SMIL will only be
relevant to later SVG Specifications.

In the interim, UAs should define their own behavior, even if it might not
currently be interoperable. It is anticipated that further coordination with
the SYMM WG based on feedback from implementor experience will yeild an
acceptable and interoperable solution for future specifications.

Please tell us within two weeks if this response does not address these
issues.

Regards-
Doug, on behalf of the SVG WG
 
Jean-Claude Dufourd wrote:
| 
| 
| We are wondering about the consequences of animating the xlink:href 
| attribute of a running media.
| 
| Ex. :
| <video xlink:href="vid1.3gp" begin="0s" dur="media">
|   <set attributeName="xlink:href" to="vid2.3gp" begin="1s" dur="2s"/>
| </video>
| 
| - at 0s, <video> renders "vid1.3gp"
| - at 1s, <video> renders "vid2.3gp". Is "vid2.3gp" started at 1s into 
| the media, or at its beginning ?
| Should "vid1.3gp" be kept active in background ?
| - at 3s, <video> renders "vid1.3gp" again. Does it restart at the 
| beginning or at 3s ?
| Should "vid2.3gp" be kept active in background ?
| 
| What is the effect on the timing of <video> if the implicit 
| durations of 
| "vid1.3gp" and "vid2.3gp" are different ?
| Should the 'active end' be reevaluated at each change of the 
| xlink:href 
| attribute ?
| What is the consequence of the connexion and buffering phase which 
| appears at the change between "vid1.3gp" and "vid2.3gp" ?
| 
| We do not think the list of questions ends here. We believe this is a 
| Pandora's box.
| One possible solution is to adopt text to the effect that changes to 
| xlink:href are only taken into account when the media element 
| is not active.
| 
| Thanks
| 
| Nicolas Pierre, Erwann Gouesbet, Julien Tranchant and
| Jean-Claude Dufourd
| 
Received on Friday, 3 March 2006 16:22:29 GMT

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