ISSUE-306: Appendix N.2 omits fractional time expressions

Fractional time expressions in N.2 media timeBase

Appendix N.2 omits fractional time expressions

State:

OPEN

Product:

TTML 1.0

Raised by:

Nigel Megitt

Opened on:

2014-05-02

Description:

Appendix N.2 [1] describes the cases when time expressions include frames and subframes, and when it includes ticks, but not when it includes fractions of seconds. This usage is present in EBU-TT-D [2].

[1] http://www.w3.org/TR/ttml1/#time-expression-semantics-media
[2] https://tech.ebu.ch/docs/tech/tech3380.pdf

This could be fixed by adding the following alternative equation for M in the green box in this section immediately after the equation that uses frames and subFrames:

++++
OR

M = referenceBegin + 3600 * hours + 60 * minutes + seconds + fraction
++++

and changing

----
the hours, minutes, seconds, frames, subFrames components are extracted from time expression if present, or zero if not present;
----

to

====
the hours, minutes, seconds, frames, subFrames, fraction components are extracted from time expression if present, or zero if not present;
====

One could argue that this interpretation is obvious and does not require elaboration however I think it should be present for completeness. Otherwise when this appendix is made normative it could be interpreted that fractions of seconds are not permitted in time expressions when the timeBase is media, which I believe would be an error.

Related Actions Items:

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Related emails:

1. {minutes} TTWG Meeting 19/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-19)
2. RE: {agenda} TTWG Meeting 19/6/2014 (from mdolan@newtbt.com on 2014-06-18)
3. {agenda} TTWG Meeting 19/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-18)
4. RE: {agenda} TTWG Meeting 12/6/2014 (from mdolan@newtbt.com on 2014-06-12)
5. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
6. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
7. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
8. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
9. {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
10. RE: {agenda} TTWG Meeting 5/6/2014 (from mdolan@newtbt.com on 2014-06-04)
11. {agenda} TTWG Meeting 5/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-04)
12. {agenda} TTWG Meeting 29/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-28)
13. Re: {agenda} TTWG Meeting 8/5/2014 (from tmichel@w3.org on 2014-05-08)
14. {agenda} TTWG Meeting 8/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-07)
15. ISSUE-306 (Fractional time expressions in N.2 media timeBase): Appendix N.2 omits fractional time expressions [TTML 1.0] (from sysbot+tracker@w3.org on 2014-05-02)

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