ISSUE-2145: Clarify media timeline and document timeline

media/document timeline

Clarify media timeline and document timeline

SVG 1.2 Tiny: Last Call
Raised by:
Doug Schepers
Opened on:
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.

Related Actions Items:
Related emails:
  1. Re: [1.2T-LC] Comments on Last Call WD of SVG T1.2 (ISSUE-2145) (from on 2008-11-04)
  2. Re: [1.2T-LC] Comments on Last Call WD of SVG T1.2 (ISSUE-2145) (from on 2008-11-03)
  3. SVG/profiles/1.2T/publish multimedia.html,1.127,1.128 single-page.html,1.188,1.189 (from on 2008-11-03)
  4. SVG/profiles/1.2T/master multimedia.html,1.119,1.120 (from on 2008-11-03)
  5. SVG/profiles/1.2T/master multimedia.html,1.118,1.119 (from on 2008-11-03)
  6. SVG/profiles/1.2T/publish multimedia.html,1.126,1.127 single-page.html,1.187,1.188 (from on 2008-11-03)
  7. SVG/profiles/1.2T/master multimedia.html,1.117,1.118 text.html,1.160,1.161 (from on 2008-11-03)
  8. Re: [1.2T-LC] Comments on Last Call WD of SVG T1.2 (ISSUE-2145) (from on 2008-10-29)
  9. SVG/profiles/1.2T doc-svgt12.html,NONE,1.1 (from on 2008-10-28)
  10. Minutes, 23 Oct SVG WG f2f (from on 2008-10-24)
  11. SVG/profiles/1.2T/master multimedia.html,1.107,1.108 (from on 2008-10-23)
  12. Minutes, SVG Marathon telcon Friday October 17 2008 (from on 2008-10-18)
  13. Re: Logistics of Open Issues (from on 2008-10-16)
  14. Logistics of Open Issues (from on 2008-10-16)
  15. Summary of my comments (from on 2008-10-14)
  16. Re: [1.2T-LC] Comments on Last Call WD of SVG T1.2 (from on 2008-10-13)
  17. ISSUE-2145 (media/document timeline): Clarify media timeline and document timeline [Last Call: SVG 1.2 Tiny ] (from on 2008-10-13)

Related notes:

Compromise. Made certain changes, explained that SMIL covers the rest.

Doug Schepers, 31 Oct 2008, 12:59:12

Compromise, most requested changes made. Commenter satisfied:

Doug Schepers, 3 Nov 2008, 18:10:53

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