ISSUE-330: Is Presented Region a synonym for temporally active region?

Is Presented Region a synonym for temporally active region?

Is Presented Region a synonym for temporally active region?

State:
CLOSED
Product:
TTML IMSC 1.0
Raised by:
Nigel Megitt
Opened on:
2014-07-28
Description:
This issue is related to Issue-314 and was generated as part of the resolution to Issue-313.

TTML 1 SE §9.3.2 [1] uses the term "temporally active region" to define regions that are included in the construction of intermediate synchronic documents "for the purposes of performing presentation processing". Issue-314 covers the point that this term is not defined.

[1] http://www.w3.org/TR/ttml1/#semantics-region-layout-step-1

IMSC 1 editor's draft §4.6.1 [2] defines and uses the term "presented region" to define regions that may be presented at any moment, and in all but one case references presented region with respect to an intermediate synchronic document.

[2] https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml-ww-profiles/ttml-ww-profiles.html#presented-region

It looks as though these two terms may be synonyms, or very closely related to each other. If this is the case then IMSC 1 should reference the defined term in TTML 1 SE (if need be, after the resolution to Issue-314). If it is not the case then the difference should be clarified making reference to the similar concept.

For example, if the resolution to Issue-314 is to define temporally active region in TTML 1 SE as any region that is either temporally active or has content selected into it that is temporally active, or has showBackground="always", then Presented Region in IMSC 1 may be defined as:
any temporally active region which satisfies all of the following conditions...,
where those conditions include [those currently specified] and those noted additionally by Glenn in response to Issue-313 [3], i.e. the values of the attributes tts:display, tts:visibility, tts:extent and tts:opacity are such that marks may be made by the region or its contents.

[3] http://lists.w3.org/Archives/Public/public-tt/2014Jul/0036.html

This issue created as per Action-308.
Related Actions Items:
Related emails:
  1. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from glenn@skynav.com on 2014-08-21)
  2. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-20)
  3. {agenda} TTWG Meeting 21/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-20)
  4. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-15)
  5. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-15)
  6. {minutes} TTWG Meeting 14/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-14)
  7. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-14)
  8. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-14)
  9. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-14)
  10. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-14)
  11. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-14)
  12. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-14)
  13. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-14)
  14. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-14)
  15. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-14)
  16. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-13)
  17. {agenda} TTWG Meeting 14/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-13)
  18. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-13)
  19. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from glenn@skynav.com on 2014-08-13)
  20. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-13)
  21. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-13)
  22. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-13)
  23. Re: ISSUE-310 (progressivelyDecodable needs hierarchical definition): Forward reference rule doesn't take into account child elements [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-13)
  24. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-13)
  25. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-08-13)
  26. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from pal@sandflow.com on 2014-08-12)
  27. Re: {agenda} TTWG Meeting 7/8/2014 (from pal@sandflow.com on 2014-08-06)
  28. {agenda} TTWG Meeting 7/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-06)
  29. {agenda} TTWG Meeting 31/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-30)
  30. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-07-28)
  31. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from nigel.megitt@bbc.co.uk on 2014-07-28)
  32. Re: ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from glenn@skynav.com on 2014-07-28)
  33. ISSUE-330 (Is Presented Region a synonym for temporally active region?): Is Presented Region a synonym for temporally active region? [TTML IMSC 1.0] (from sysbot+tracker@w3.org on 2014-07-28)

Related notes:

The phrase "temporally active region" is not synonymous with "presented region", since a temporally active region that contains no content will not produce any rendering unless showBackground is "always". See further details in Issue-314 comments.

Glenn Adams, 28 Jul 2014, 15:19:14

In that case it would make sense to define 'presented region' in terms of a 'temporally active region' that either contains visible content with opacity >0 or has showBackground="always" and a backgroundColour with opacity >0.

Nigel Megitt, 28 Jul 2014, 15:54:08

Addressed at https://dvcs.w3.org/hg/ttml/rev/ceaa219bfbcc

Pierre-Anthony Lemieux, 12 Aug 2014, 14:51:38

The updated text uses phrases such as ‘earlier/later in the document’ - this does not address my original concern, that the test for earlier and later is not precisely enough defined. Do you mean to compare the byte locations of the opening tag of the elements in the flattened document structure, for example?

It is also unclear in the new wording (list item 2) how an ISD “maps” to a content element. An ISD is typically constructed from multiple elements simultaneously. There seems to be an assumption that an ISD can only relate to a single p, which is such a significant constraint that I wonder if it was intended.

Take this example:

<p id="p1" begin="00:01:00" end="00:02:00">
[some stuff]
</p>
<p id="p2" begin="00:01:30" end="00:01:45">
[some other stuff]
</p>

We have here the following ISDs:
1. 00:01:00 containing p1
2. 00:01:30 containing p1 and p2
3. 00:01.45 containing p1
4. 00:02:00 containing nothing

Is this progressively decodable? Did the 3rd ISD above 'map' to p2? It doesn't itself contain p2: it simply has its timing derived from p2.

Nigel Megitt, 13 Aug 2014, 09:34:50

Apologies the previous note should have been on Issue-310.

Nigel Megitt, 13 Aug 2014, 09:37:02

Review comment: this edit resolves the issue, for me.

Nigel Megitt, 13 Aug 2014, 09:41:12

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