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ISSUE-2145 (media/document timeline): Clarify media timeline and document timeline [Last Call: SVG 1.2 Tiny ]

From: SVG Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Mon, 13 Oct 2008 13:39:19 -0400 (EDT)
To: public-svg-wg@w3.org
Message-Id: <20081013173919.C45334DD62@crusher.w3.org>

ISSUE-2145 (media/document timeline): Clarify media timeline and document timeline [Last Call: SVG 1.2 Tiny ]


Raised by: Doug Schepers
On product: Last Call: SVG 1.2 Tiny 

Cyril Concolato
* Section 12.1.1 Media timeline and document timeline
The specification says that media elements which are loaded only when they become visible for the fist time may introduce delay. In that case, what document time corresponds to the beginning of the media timeline ? The begin value or the begin value + the delay ? Is it correct to say that assuming timelines are locked, then the UA has to adjust playback to cope with the load time (similarly to a timelineBegin=onStart)?

"the value of the 'syncBehavior' attribute are replaced from the default one ('default', interpreted as 'locked' in that case since the 'syncBehaviorDefault' is not specified) to 'independent'."
"the value of the 'syncBehavior' attribute are set to 'independent'."
The current wording 'interpreted as locked' is ambiguous. The actual interpretation of 'default' is implementation specific and the spec seems to imply that it should be interpreted as locked all the time.

Could you clarify what the exact locking behavior is ? If a media timeline is locked to the document timeline and if the video is paused, what happens ? Is the document timeline locked? 

The xlink:href of audio and video says:
"When the value of the attribute is animated or otherwise modified, if the media play time can be controlled, then the media timeline is restarted. "
First, the term 'play time' is not defined. I suggest changing "media play time" to "media timeline". But if the media timeline is locked, changing the xlink:href to a new value, without changing the begin value, will not restart the media timeline (or it will restart it but at time = the document time when the change happened). What happens if the media timeline cannot be controlled?

The specification should say what happens when a video/audio element points to a file or a set of streams containing multiple audio tracks (english and french, or AAC and AC3) or multiple video tracks.

Received on Monday, 13 October 2008 17:39:28 UTC

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