ISSUE-188: Bounding TTML (was: SDP-US) rendering complexity

render-complexity

Bounding TTML (was: SDP-US) rendering complexity

State:
POSTPONED
Product:
TTML Simple Delivery Profile for Closed Captions (US)
Raised by:
Pierre-Anthony Lemieux
Opened on:
2012-09-26
Description:
Bounding SDP-US rendering complexity
====================================

What
----

SDP-US is a profile of TTML that specifies constraints such as supported TTML features and number of regions active at any given time. It does not however impose bounds on key aspects of rendering complexity, such as character and background drawing rates. Without such bounds, a valid SDP-US document might not successfully play on all implementations or, equivalently, determining the processing requirements of an implementation is not possible.

CFF-TT is a profile of TTML developed by the DECE consortium (http://uvvu.com) for internet delivery of subtitles and captions. Consumer devices implementing CFF-TT are expected to be widely deployed. The CFF-TT specification is publicly available at http://uvvu.com/docs/public/tspec/CFFMediaFormat-1.0.4.pdf.

As with SDP-US, CFF-TT specifies supported TTML features -- largely a superset of the features supported by SDP-US. To further simplify implementation and improve interoperability, CFF-TT also imposes bounds on rendering complexity through the use of an hypothetical rendering model.

SDP-US should consider adopting, a subset of or in its entirety, the rendering complexity bounds (and rendering model) defined by CFF-TT.

Why
---

Such adoption would futher:
- simplify implementations and improve interoperability by bounding rendering (and thus document) complexity
- encourage adoption of SDP-US and TTML by ensuring that SDP-US content can be played on any CFF-compliant CE device

How
---

Adopting the CFF-TT hypothetical renderer and bounds on document complexity could be achieved in a number of ways, including:

(a) mapping the CFF-TT rendering model to the existing (XSL-based) TTML rendering model
(b) referencing the relevant sections of the CFF-TT specification defining the CFF-TT rendering model
(c) importing the CFF-TT rendering model into the SDP-US specification
Related Actions Items:
Related emails:
  1. TTML Minutes for 15/11/13 (from nigel.megitt@bbc.co.uk on 2013-11-21)
  2. {minutes} TTML Meeting of 24/10/13 (from glenn@skynav.com on 2013-10-24)
  3. RE: TTML Agenda for 24/10/13 (from mdolan@newtbt.com on 2013-10-23)
  4. TTML Agenda for 24/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-23)
  5. TTWG Minutes Dec 6, 2012 (from momartin@microsoft.com on 2012-12-12)
  6. TTWG Meeting Minutes Dec 6 (from momartin@microsoft.com on 2012-12-06)
  7. RE: TTML Agenda for 28/11/12 (from mdolan@newtbt.com on 2012-11-29)
  8. TTML Agenda for 28/11/12 (from Sean.Hayes@microsoft.com on 2012-11-29)
  9. TTWG Meeting Minutes Nov 15, 2012 (from momartin@microsoft.com on 2012-11-15)
  10. RE: TTML Agenda for 15/11/12 (from mdolan@newtbt.com on 2012-11-15)
  11. TTML Agenda for 15/11/12 (from Sean.Hayes@microsoft.com on 2012-11-15)
  12. RE: Suggested Text for Issue-188 to Close Action-128 (from momartin@microsoft.com on 2012-11-12)
  13. RE: Suggested Text for Issue-188 to Close Action-128 (from Sean.Hayes@microsoft.com on 2012-11-12)
  14. RE: Suggested Text for Issue-188 to Close Action-128 (from momartin@microsoft.com on 2012-11-12)
  15. Re: Suggested Text for Issue-188 to Close Action-128 (from glenn@skynav.com on 2012-11-12)
  16. Suggested Text for Issue-188 to Close Action-128 (from momartin@microsoft.com on 2012-11-07)
  17. RE: TTWG Meeting Minutes Nov 1: http://www.w3.org/2012/11/01-tt-minutes.html (from momartin@microsoft.com on 2012-11-05)
  18. TTML Agenda for 1/11/12 (from Sean.Hayes@microsoft.com on 2012-11-01)
  19. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-10-04)
  20. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-10-03)
  21. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-10-03)
  22. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-10-03)
  23. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-10-03)
  24. Re: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-10-02)
  25. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-10-02)
  26. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from Sean.Hayes@microsoft.com on 2012-10-02)
  27. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-10-02)
  28. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from Sean.Hayes@microsoft.com on 2012-10-02)
  29. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-10-02)
  30. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-10-01)
  31. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-09-28)
  32. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-09-28)
  33. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-09-28)
  34. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-09-28)
  35. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from mdolan@newtbt.com on 2012-09-27)
  36. RE: ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from John.Birch@screensystems.tv on 2012-09-27)
  37. ISSUE-188 (render-complexity): Bounding SDP-US rendering complexity [Simple Delivery Profile for Closed Captions] (from sysbot+tracker@w3.org on 2012-09-26)

Related notes:

TTWG Oct 4: http://www.w3.org/2012/10/04-tt-minutes.html
Relates to Action-113: https://www.w3.org/AudioVideo/TT/tracker/actions/113

Monica Martin, 4 Oct 2012, 16:00:02

TTWG Nov 1: http://lists.w3.org/Archives/Public/public-tt/2012Nov/0008.html (updated minutes)

Resolved Nov 1 to:
a. Frame text in future needs section on use of a future rendering model.
b. Consider whether to develop a separate technical report on rendering model.
c. Open action to mmartin3 on text for item a (Action-128).

Monica Martin, 6 Nov 2012, 01:12:53

Proposed text for "future work" is not acceptable.

Glenn Adams, 12 Nov 2012, 17:45:15

TTWG Nov 15: TTWG Nov 15 http://www.w3.org/2012/11/15-tt-minutes.html

Resolved to re-frame updated proposals from Monica and Sean to include text on constraints on authoring for graphics performance. Leave to discretion of the editor.

Sean's text updated from Monica's original post: http://lists.w3.org/Archives/Public/public-tt/2012Nov/0018.html

Monica Martin, 16 Nov 2012, 02:08:02

Done:

https://dvcs.w3.org/hg/ttml/rev/5c9941317402

Glenn Adams, 29 Nov 2012, 06:59:58

TTWG minutes: http://lists.w3.org/Archives/Public/public-tt/2012Nov/0029.html

Agreed on text to add to A.3 in SDP-US in anticipation of addressing Issue-188 in a future version of TTML.

Defer definition of a rendering model to TTML v.next.

Reassign target to TTML v.next.

Monica Martin, 2 Dec 2012, 23:20:30

Renaming from SDP-US to TTML as this has been assigned to TTML.next.

Monica Martin, 30 Jan 2013, 19:56:42

Will fall under IMSC as well
Nigel: P2 for TTML2, P1 for IMSC

Philippe Le Hégaret, 24 Oct 2013, 15:29:48

Agreed to postpone until SDP maintenance activity resumes, and add a note referencing the HRM in IMSC.

Nigel Megitt, 15 Nov 2013, 09:10:07

Changelog:

Created issue 'Bounding SDP-US rendering complexity' nickname render-complexity owned by Pierre-Anthony Lemieux on product Simple Delivery Profile for Closed Captions, description 'Bounding SDP-US rendering complexity
====================================

What
----

SDP-US is a profile of TTML that specifies constraints such as supported TTML features and number of regions active at any given time. It does not however impose bounds on key aspects of rendering complexity, such as character and background drawing rates. Without such bounds, a valid SDP-US document might not successfully play on all implementations or, equivalently, determining the processing requirements of an implementation is not possible.

CFF-TT is a profile of TTML developed by the DECE consortium (http://uvvu.com) for internet delivery of subtitles and captions. Consumer devices implementing CFF-TT are expected to be widely deployed. The CFF-TT specification is publicly available at http://uvvu.com/docs/public/tspec/CFFMediaFormat-1.0.4.pdf.

As with SDP-US, CFF-TT specifies supported TTML features -- largely a superset of the features supported by SDP-US. To further simplify implementation and improve interoperability, CFF-TT also imposes bounds on rendering complexity through the use of an hypothetical rendering model.

SDP-US should consider adopting, a subset of or in its entirety, the rendering complexity bounds (and rendering model) defined by CFF-TT.

Why
---

Such adoption would futher:
- simplify implementations and improve interoperability by bounding rendering (and thus document) complexity
- encourage adoption of SDP-US and TTML by ensuring that SDP-US content can be played on any CFF-compliant CE device

How
---

Adopting the CFF-TT hypothetical renderer and bounds on document complexity could be achieved in a number of ways, including:

(a) mapping the CFF-TT rendering model to the existing (XSL-based) TTML rendering model
(b) referencing the relevant sections of the CFF-TT specification defining the CFF-TT rendering model
(c) importing the CFF-TT rendering model into the SDP-US specification' non-public

Pierre-Anthony Lemieux, 26 Sep 2012, 20:15:58

Status changed to 'open'

Monica Martin, 4 Oct 2012, 16:11:16

Product changed to DFXP v.next

Monica Martin, 2 Dec 2012, 23:20:30

title changed to 'Bounding TTML (was: SDP-US) rendering complexity'

Monica Martin, 30 Jan 2013, 19:56:42

Product changed to Simple Delivery Profile for Closed Captions

Nigel Megitt, 15 Nov 2013, 09:10:07

Status changed to 'postponed'

Nigel Megitt, 15 Nov 2013, 09:10:07


David Singer <singer@apple.com>, Nigel Megitt <nigel.megitt@bbc.co.uk>, Chairs, Thierry Michel <tmichel@w3.org>, Philippe Le Hégaret <plh@w3.org>, Staff Contacts
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <w3t-sys@w3.org>.
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