ISSUE-341: ambiguous definition for determination of descendant region identifier

ambiguous definition for determination of descendant region identifier

State:
OPEN
Product:
TTML 1.0
Raised by:
Glenn Adams
Opened on:
2014-08-27
Description:
Step 3 of the [association region] procedure in Section 9.3.2 is ambiguous if multiple descendants are associated with a region (possibly distinct).

Suggest changing from:

"if the element contains a descendant element that specifies a region attribute, then the element is associated with the region referenced by that attribute;"

to

"if the element contains a descendant element that specifies a region attribute, then the element is associated with the first region referenced by that attribute using a breadth-first pre-traversal search of descendant elements;"
Related Actions Items:
Related emails:
  1. {minutes} TTWG Meeting 2016-06-09 (from nigel.megitt@bbc.co.uk on 2016-06-09)
  2. Re: {agenda} TTWG Meeting 2016-06-09 (from pal@sandflow.com on 2016-06-09)
  3. {agenda} TTWG Meeting 2016-06-09 (from nigel.megitt@bbc.co.uk on 2016-06-07)
  4. {agenda} TTWG Meeting 2016-05-26 (from nigel.megitt@bbc.co.uk on 2016-05-24)
  5. {agenda} TTWG Meeting 2016-05-19 (from nigel.megitt@bbc.co.uk on 2016-05-17)
  6. Re: {agenda} TTWG Meeting 2016-05-05 (from nigel.megitt@bbc.co.uk on 2016-05-04)
  7. {agenda} TTWG Meeting 2016-05-05 (from nigel.megitt@bbc.co.uk on 2016-05-03)
  8. Re: {agenda} TTWG Meeting 2016-04-28 (from nigel.megitt@bbc.co.uk on 2016-04-27)
  9. {agenda} TTWG Meeting 2016-04-28 (from nigel.megitt@bbc.co.uk on 2016-04-27)
  10. {agenda} TTWG Meeting 2016-04-21 (from nigel.megitt@bbc.co.uk on 2016-04-19)
  11. {agenda} TTWG Meeting 2016-04-14 (from nigel.megitt@bbc.co.uk on 2016-04-12)
  12. {agenda} TTWG Meeting 2016-04-07 (from nigel.megitt@bbc.co.uk on 2016-04-06)
  13. Re: {agenda} TTWG Meeting 2016-03-24 (from tai@irt.de on 2016-03-23)
  14. {agenda} TTWG Meeting 2016-03-24 (from nigel.megitt@bbc.co.uk on 2016-03-23)
  15. Re: {agenda} TTWG Meeting 2016-03-17 (from nigel.megitt@bbc.co.uk on 2016-03-17)
  16. {agenda} TTWG Meeting 2016-03-17 (from nigel.megitt@bbc.co.uk on 2016-03-15)
  17. {agenda} TTWG Meeting 2016-03-10 (from nigel.megitt@bbc.co.uk on 2016-03-08)
  18. {agenda} TTWG Meeting 2016-03-03 (from nigel.megitt@bbc.co.uk on 2016-03-01)
  19. {agenda} TTWG Meeting 2015-12-25 (from nigel.megitt@bbc.co.uk on 2016-02-23)
  20. {agenda} TTWG Meeting 2016-02-18 (from nigel.megitt@bbc.co.uk on 2016-02-16)
  21. {agenda} TTWG Meeting 2016-02-11 (from nigel.megitt@bbc.co.uk on 2016-02-09)
  22. {agenda} TTWG Meeting 2016-02-04 [30 minutes later than usual] (from nigel.megitt@bbc.co.uk on 2016-02-03)
  23. {agenda} TTWG Meeting 2016-01-28 (from nigel.megitt@bbc.co.uk on 2016-01-26)
  24. {agenda} TTWG Meeting 2016-01-21 (from nigel.megitt@bbc.co.uk on 2016-01-19)
  25. Re: {agenda} TTWG Meeting 2016-01-14 (from dronca@netflix.com on 2016-01-14)
  26. {agenda} TTWG Meeting 2016-01-14 (from nigel.megitt@bbc.co.uk on 2016-01-12)
  27. Re: {agenda} TTWG Meeting 2016-01-07 (from tmichel@w3.org on 2016-01-05)
  28. {agenda} TTWG Meeting 2016-01-07 (from nigel.megitt@bbc.co.uk on 2016-01-05)
  29. {agenda} TTWG Meeting 2015-12-17 (from nigel.megitt@bbc.co.uk on 2015-12-16)
  30. {agenda} TTWG Meeting 2015-12-10 (from nigel.megitt@bbc.co.uk on 2015-12-09)
  31. {agenda} TTWG Meeting 2015-12-03 (from nigel.megitt@bbc.co.uk on 2015-12-02)
  32. Re: {agenda} TTWG Meeting 2015-11-26 (from nigel.megitt@bbc.co.uk on 2015-11-26)
  33. Re: {agenda} TTWG Meeting 2015-11-26 (from tmichel@w3.org on 2015-11-25)
  34. {agenda} TTWG Meeting 2015-11-26 (from nigel.megitt@bbc.co.uk on 2015-11-25)
  35. {agenda} TTWG Meeting 2015-11-19 (from nigel.megitt@bbc.co.uk on 2015-11-18)
  36. {agenda} TTWG Meeting 2015-11-12 (from nigel.megitt@bbc.co.uk on 2015-11-11)
  37. {agenda} TTWG Meeting 2015-10-22 (from nigel.megitt@bbc.co.uk on 2015-10-21)
  38. Re: TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-21)
  39. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  40. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  41. RE: TTML2 anonymous inline region creation (from John.Birch@screensystems.tv on 2015-10-21)
  42. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  43. RE: TTML2 anonymous inline region creation (from John.Birch@screensystems.tv on 2015-10-21)
  44. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  45. Re: TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-20)
  46. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  47. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  48. TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-20)
  49. {agenda} TTWG Meeting 2015-10-15 (from nigel.megitt@bbc.co.uk on 2015-10-14)
  50. RE: {agenda} TTWG Meeting 2015-10-08 (from mdolan@newtbt.com on 2015-10-08)
  51. {agenda} TTWG Meeting 2015-10-08 (from nigel.megitt@bbc.co.uk on 2015-10-07)
  52. {agenda} TTWG Meeting 2015-10-01 (from nigel.megitt@bbc.co.uk on 2015-10-01)
  53. {agenda} TTWG Meeting 2015-09-24 (from nigel.megitt@bbc.co.uk on 2015-09-23)
  54. {agenda} TTWG Meeting 2015-09-17 (from nigel.megitt@bbc.co.uk on 2015-09-16)
  55. {agenda} TTWG Meeting 2015-09-03 (from nigel.megitt@bbc.co.uk on 2015-09-03)
  56. {agenda} TTWG Meeting 2015-08-27 (from nigel.megitt@bbc.co.uk on 2015-08-26)
  57. Re: {agenda} TTWG Meeting 2015-08-20 (from nigel.megitt@bbc.co.uk on 2015-08-19)
  58. RE: {agenda} TTWG Meeting 2015-08-20 (from mdolan@newtbt.com on 2015-08-19)
  59. {agenda} TTWG Meeting 2015-08-20 (from nigel.megitt@bbc.co.uk on 2015-08-19)
  60. {agenda} TTWG Meeting 2015-08-13 (from nigel.megitt@bbc.co.uk on 2015-08-12)
  61. {agenda} TTWG Meeting 2015-08-06 (from nigel.megitt@bbc.co.uk on 2015-08-05)
  62. {agenda} TTWG Meeting 2015-07-30 (from nigel.megitt@bbc.co.uk on 2015-07-29)
  63. Re: {agenda} TTWG Meeting 2015-07-23 (from glenn@skynav.com on 2015-07-23)
  64. {agenda} TTWG Meeting 2015-07-23 (from nigel.megitt@bbc.co.uk on 2015-07-22)
  65. {minutes} TTWG Meeting 2015-07-09 (from nigel.megitt@bbc.co.uk on 2015-07-09)
  66. {agenda} TTWG Meeting 2015-07-09 (from nigel.megitt@bbc.co.uk on 2015-07-08)
  67. Re: {agenda} TTWG Meeting 2015-07-02 (from nigel.megitt@bbc.co.uk on 2015-07-02)
  68. Re: {agenda} TTWG Meeting 2015-07-02 (from glenn@skynav.com on 2015-07-02)
  69. Re: {agenda} TTWG Meeting 2015-07-02 (from pal@sandflow.com on 2015-07-01)
  70. {agenda} TTWG Meeting 2015-07-02 (from nigel.megitt@bbc.co.uk on 2015-07-01)
  71. {agenda} TTWG Meeting 2015-06-11 (from nigel.megitt@bbc.co.uk on 2015-06-10)
  72. Re: Pruning of content elements based on the Intermediate Synchronic Document Construction (from nigel.megitt@bbc.co.uk on 2015-06-08)
  73. Re: Pruning of content elements based on the Intermediate Synchronic Document Construction (from tai@irt.de on 2015-06-08)
  74. Re: Pruning of content elements based on the Intermediate Synchronic Document Construction (from tai@irt.de on 2015-06-05)
  75. {minutes} TTWG Meeting 2015-06-04 (from nigel.megitt@bbc.co.uk on 2015-06-04)
  76. {agenda} TTWG Meeting 2015-06-04 (from nigel.megitt@bbc.co.uk on 2015-06-03)
  77. {agenda} TTWG Meeting 4/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-03)
  78. ISSUE-341: ambiguous definition for determination of descendant region identifier [TTML 1.0] (from sysbot+tracker@w3.org on 2014-08-27)

Related notes:

I would suggest that the element is duplicated for each region referenced by a descendant element.

This allows for example:

<style id="div_style" tts:backgroundColor="blue"/>
...
<div style="div_style">
<p region="r1">Hello</p>
<p region="r2">Goodbye</p>
</div>

to resolve effectively to:

<div tts:backgroundColor="blue" region="r1"><p>Hello</p></div>
<div tts:backgroundColor="blue" region="r2"><p>Goodbye</p></div>

Otherwise with the proposal in the Description above, the second p would be drawn without a background colour, which is non-obvious to the author.

As well as duplicating styles this would also apply the same metadata from the div to every p, in case that's used somehow - copyright, lang or role could be examples I suppose.

Nigel Megitt, 29 May 2015, 13:11:09

An additional issue that was discussed on the TTWG mailing list and discussed in the meeting on the 4th of June 2015:

The current algorithm for the construction of an Intermediate Synchronic Document would result in untintended pruning of content. Example:

Given the following simplified TTML document:

<tt>
<head>
<layout>
<region id="divRegion" ...../>
<region id="paragraphRegion" ...../>
</layout>
</head>
<body>
<div region="divRegion">
<p region="paragraphRegion" begin="00:00:00.000" end="00:00:02.000" >Hello world!</p>
</div>
</body>
</tt>

The corresponding ISD for the interval [0s, 2s) would look like this:

<tt>
<head>
<layout>
<region id="divRegion" ...../>
<region id="paragraphRegion" ...../>
</layout>
</head>
</tt>

Andreas Tai, 17 Jun 2015, 15:47:10

Before I can fully resolve my understanding of the intended semantics, I believe we need to determine which of the following semantics apply when @region is specified on an element A and one of its descendant elements D and the two specified regions, R(A) and R(D), are different:

1. R(D) (temporarily) OVERRIDES the region on A, forcing A to be selected into R(D); in this case, D is not selected when evaluating R(A), but A is selected when evaluating R(D): thus D is selected for R(D), but not selected for R(A)

2. R(A) (temporarily) OVERRIDES the region on D, forcing D to be selected into R(A); in this case, D is selected when evaluating R(A), but A is not selected when evaluating R(D): thus D is selected for R(A), but not selected for R(D)

3. R(D) DOES NOT OVERRIDE the region on A; in this case, D is not selected when evaluating R(A), and A is not selected when evaluating R(D): thus D is never selected

4. R(A) DOES NOT OVERRIDE the region on D; in this case, A is not selected when evaluating R(D), and D is not selected when evaluating R(A): thus D is never selected

Of these four options, I believe #1, R(D) overrides R(A), is the most intuitive and useful choice.

Glenn Adams, 7 Jun 2016, 19:22:26

Comment duplicated in the equivalent issue https://github.com/w3c/ttml1/issues/194

Nigel Megitt, 9 Jun 2016, 14:28:48

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