IRC log of tt on 2018-05-31

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Meeting: Timed Text Working Group Teleconference
14:01:18 [trackbot]
Date: 31 May 2018
14:01:24 [nigel]
Log: https://www.w3.org/2018/05/31-tt-irc
14:02:09 [nigel]
Present: Nigel, Glenn, Cyril
14:02:15 [nigel]
Regrets: Pierre, Andreas, Thierry
14:02:21 [nigel]
Chair: Nigel
14:02:25 [nigel]
scribe: nigel
14:02:29 [nigel]
Topic: This Meeting
14:02:44 [nigel]
Glenn: The main thing I want to do today is review #794 with a view to merging early.
14:03:41 [nigel]
Nigel: Today we have some regrets, so let's make what progress we can.
14:04:02 [nigel]
.. On the agenda is TTWG Charter, TTML2, and I'm not sure what else we can cover.
14:04:19 [nigel]
.. Aside from #794 is there anything else you'd like to make sure we look at, or any other
14:04:20 [nigel]
.. business?
14:04:31 [nigel]
Glenn: #770.
14:04:32 [nigel]
Nigel: OK
14:04:49 [nigel]
Glenn: In the remainder of the time I'd like to go over the ones ready to go pending
14:05:00 [nigel]
.. approval of recent updates to address comments, that are marked as pending re-review
14:05:23 [nigel]
.. in the pull request list for TTML2. There are a couple of older ones with Nigel's name on
14:05:27 [nigel]
.. that maybe we can do in realtime.
14:05:30 [nigel]
Nigel: OK
14:05:49 [nigel]
Glenn: #703 and #755 I think.
14:06:06 [nigel]
Cyril: Nothing more from me.
14:06:11 [nigel]
Topic: TTWG Charter
14:06:22 [nigel]
Nigel: Just to note for the minutes we are now operating under a new Charter:
14:06:38 [nigel]
-> https://www.w3.org/2018/05/timed-text-charter.html TTWG Charter 2018
14:06:50 [nigel]
Nigel: Thanks everyone for contributing to that and working on it.
14:06:53 [nigel]
Glenn: When does it go to?
14:06:57 [nigel]
Nigel: 31 May 2020.
14:07:33 [nigel]
.. One other thing for the notes only given the attendees today: there's no change in scope
14:07:56 [nigel]
.. so any invited experts should _not_ be ejected and need to request re-invitation. If that
14:08:01 [nigel]
.. does happen please let me know ASAP.
14:08:41 [nigel]
Topic: Clean up and refactor features (#688, #763, #789, #790, #791, #792, #… ttml2#794
14:08:46 [nigel]
github: https://github.com/w3c/ttml2/pull/794
14:09:20 [nigel]
Glenn: Summarising the changes, there were some comments on how to factor the condition
14:09:35 [nigel]
.. features and I adopted as you suggested, pretty much exactly, and also for the rubyAlign-withBase
14:09:48 [nigel]
.. I adopted your proposal. On the animate you had a question about if animate covers
14:10:00 [nigel]
.. everything, and it was ambiguous to me as well. In a previous meeting we had discussed
14:10:13 [nigel]
.. animate-related features and I said I would do some work to tie it to the calculation mode
14:10:25 [nigel]
.. and that discrete and linear would be in the minimal features, and paced and spline would
14:10:36 [nigel]
.. be separate features. I refactored animate to do that and to make sure that the animate
14:11:02 [nigel]
.. feature did include those things. I took out the `#animate-calcMode`, `#animate-keySplines`
14:11:36 [nigel]
.. and `#animate-calcMode` and added `#animate-minimal` which includes discrete
14:11:55 [nigel]
.. and linear calc modes and by virtue of that implies support for keyTimes attribute.
14:12:04 [nigel]
.. We don't need a separate feature for keyTimes since it is in the minimal set.
14:12:25 [nigel]
.. The second thing I added was `#animate-paced` for paced mode.
14:12:44 [nigel]
.. And I added `#animate-spline` which implies supporting the keySpline attribute.
14:13:01 [nigel]
.. I redefined the `#animate` feature to include all those features plus `#animate-fill` and `#animate-repeat`.
14:13:13 [nigel]
.. In my mind at this point animate is all wrapped up and doesn't make use of any negative
14:13:16 [nigel]
.. definitions.
14:13:40 [nigel]
.. And then the final comment is you had expected language about processor profiles and
14:13:55 [nigel]
.. I commented that it doesn't work because there's no such thing as prohibiting a feature
14:14:07 [nigel]
.. in a processor profile. If you don't require support then it is optional. If you require some
14:14:21 [nigel]
.. superset of a set of features then it implies that all are present, and making them optional
14:14:34 [nigel]
.. does not take them out so to speak. So there's no need to add something for processor
14:14:37 [nigel]
.. profiles by my reading.
14:15:01 [nigel]
.. I have a set of pulls stacked up pending this and Pierre suggested that we merge it ASAP.
14:15:07 [nigel]
.. So I need it to go out quickly.
14:15:27 [nigel]
Nigel: Thank you for that, good summary, it's substantive, and 8 days old.
14:15:48 [nigel]
Nigel: [looks at the changes]
14:16:26 [nigel]
Nigel: Did you fix `#display-version-2` too?
14:16:35 [nigel]
Glenn: Yes, and I spotted and fixed a typo in one of the links too.
14:16:39 [nigel]
Nigel: Thank you!
14:17:20 [nigel]
Nigel: I have some concerns about merging early, because of the nature of the changes,
14:17:27 [nigel]
.. but it's reasonable to ask in the circumstances.
14:17:43 [nigel]
Cyril: I'm fine with it since it is early but not very early. It's been more than a week.
14:19:09 [nigel]
Nigel: There's a lot to review here - I'm happy in principle with what you've described but
14:20:00 [nigel]
.. need to look at the detail - if we can close the call early today then I will complete that
14:20:02 [glenn]
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14:20:08 [nigel]
.. review, but don't foresee any problems.
14:20:49 [nigel]
SUMMARY: @nigelmegitt to complete review and add updated review status
14:21:21 [nigel]
Topic: Add features for standard and high dynamic range PNG images (#694, #6… ttml2#770
14:21:28 [nigel]
github: https://github.com/w3c/ttml2/pull/770
14:21:53 [nigel]
Glenn: The only outstanding piece on this is the reference. My opinion is we should make
14:22:08 [nigel]
.. a normative ref to the WG Note. Given the loosening of policies from HTML5 I'm pretty
14:22:24 [nigel]
.. sure that it is no longer a no-no. We can't define an HDR feature unless we can point
14:22:40 [nigel]
.. to a normative reference to a format. There's no generic format. We either put it in with
14:23:00 [nigel]
.. the WG Note as a normative ref or we don't include any HDR PNG feature.
14:23:25 [nigel]
Nigel: Ok, @plhegar didn't get back to me.
14:23:39 [nigel]
Glenn: It's been more than 14 days and we have @nigelmegitt's approval but nothing from
14:23:53 [nigel]
.. Pierre or Mike. Since this is still hanging I didn't want to merge it without group input.
14:25:34 [nigel]
Nigel: This is also related to a separate issue that I am not up to date on where I began
14:25:46 [nigel]
.. working on a pull request and realised that we probably do not want luminanceGain
14:26:21 [nigel]
.. to apply to PQ HDR image at all.
14:26:37 [nigel]
Glenn: It sounds like we can't resolve this until that's worked through.
14:26:39 [nigel]
Nigel: +1
14:27:28 [nigel]
Nigel: I've dismissed my review.
14:27:45 [nigel]
Glenn: Does IMSC 1.1 use this?
14:27:51 [nigel]
Nigel: IMSC 1.1 will need to be updated too.
14:31:22 [nigel]
Glenn: Is it really orthogonal?
14:32:23 [nigel]
Nigel: The impact comes from the comment you made Glenn about testing luminanceGain
14:32:33 [nigel]
.. without supporting PQ PNG images.
14:32:53 [nigel]
.. (also there's no way to make luminanceGain have no effect, i.e. be unity, where it is known
14:33:06 [nigel]
.. that images generate PQ pixels already).
14:33:29 [nigel]
Glenn: If we don't resolve this soon then there's a risk of needing a CR3 which I'm wary of
14:33:35 [nigel]
.. because of the time implications.
14:33:49 [nigel]
Nigel: Yes me too, I hope to be able to process this by the end of tomorrow so we can progress.
14:35:14 [nigel]
Nigel: Back to this particular topic, I think we may not need the png pq hdr feature at all,
14:35:35 [nigel]
.. though we might need a processor feature that can support identification of pq pixels
14:35:48 [nigel]
.. output from image processing, as defined by the ITU spec. That would get around the
14:37:04 [nigel]
.. need to reference the WG Note.
14:38:20 [nigel]
SUMMARY: Resolve #796 and then revisit this based on the conclusion to that issue.
14:39:05 [nigel]
Topic: Remove @style from animate and set (#703). ttml2#707
14:39:14 [nigel]
github: https://github.com/w3c/ttml2/pull/707
14:39:31 [nigel]
Glenn: Nigel you asked for minimum two values in an animation-value-list and I did that.
14:39:38 [nigel]
.. I changed the * to a + in the syntax.
14:41:11 [nigel]
Nigel: Great, and I see that I made a later comment that if you do that then it would be
14:41:25 [nigel]
.. consistent to complete the resolution of the issue by removing @style from the animate element.
14:41:31 [nigel]
.. Did you do that as part of #707?
14:41:36 [nigel]
Glenn: I did it in the schemas...
14:41:43 [nigel]
.. Yes, it's been removed from both set and animate.
14:42:19 [nigel]
Nigel: Looks good to me, I'll approve the pull request.
14:43:18 [nigel]
SUMMARY: Discussed and agreed.
14:43:21 [nigel]
github-bot, end topic
14:43:47 [nigel]
Topic: Describe generically compliant processors that support only external … ttml2#755
14:43:53 [nigel]
github: https://github.com/w3c/ttml2/pull/755
14:44:45 [nigel]
Glenn: It's tricky - in some places we have to use TTML without qualification and in others
14:44:52 [nigel]
.. it is relevant to qualify as TTML2.
14:44:54 [nigel]
Nigel: Yes!
14:46:11 [nigel]
.. I need a bit of offline time to check through that but I think it's fine.
14:46:23 [nigel]
SUMMARY: Review to continue offline
14:46:27 [nigel]
github-bot, end topic
14:46:58 [nigel]
Topic: Exclude vertical length offset as 1st component in 2 component positi… ttml2#769
14:47:03 [nigel]
github: https://github.com/w3c/ttml2/pull/769
14:47:36 [nigel]
Glenn: I made a change in the syntax as Pierre suggested.
14:53:08 [nigel]
.. Either we need to dismiss his review or wait on him for a few days. I'm willing to wait.
14:53:21 [nigel]
Nigel: I assume he'll do that, and that seems like the right approach.
14:53:47 [nigel]
Glenn: Basically the change was to match the CSS exclusions to syntactical combinations,
14:53:54 [nigel]
.. by not allowing the excluded syntax at all.
14:53:58 [nigel]
Nigel: Makes sense to me.
14:54:26 [nigel]
SUMMARY: DIscussed in WG meeting, review to continue offline
14:54:29 [nigel]
github-bot, end topic
14:54:47 [nigel]
Topic: Add explicit exceptions to ignoring element semantics with condition … ttml2#772
14:54:51 [nigel]
github: https://github.com/w3c/ttml2/pull/772
14:54:59 [nigel]
Glenn: I just did a commit last night to address comments.
14:55:14 [nigel]
.. Nigel you pointed out that the use of content element wasn't sufficiently inclusive and
14:55:25 [nigel]
.. suggested that we bring in all timed elements including region, so I introduced the
14:55:38 [nigel]
.. term timed element. I had to review all the candidates for timed elements and decide
14:55:54 [nigel]
.. what the distinguishing features were. I first thought timeContainer, but animate and set
14:56:03 [nigel]
.. have begin and end but not timeContainer, since they don't have timed children.
14:56:20 [nigel]
.. On the other hand everything had a begin, dur and end and I picked begin as a criterion.
14:56:31 [nigel]
.. Then I changed content element ref to timed element so that should address your last
14:56:36 [nigel]
.. comment and this should be ready to go.
14:56:40 [nigel]
Nigel: Sounds good to me.
14:57:06 [nigel]
Glenn: This just needs an approval - we've already passed 14 days on this one.
14:57:56 [nigel]
Nigel: OK, interesting we don't have a class that corresponds to these.
14:58:11 [nigel]
Glenn: Not in the spec - in TTV we have an IsTimedElement that does that, so implementations
14:58:22 [nigel]
.. have to do it. I'm loathe to add another class just for this purpose. A definition should
14:58:23 [nigel]
.. suffice.
14:59:42 [nigel]
Nigel: Okay, I'll review.
14:59:48 [nigel]
.. There are 16 uses of "timed element" in the spec.
14:59:54 [nigel]
Glenn: I just noticed that, I'll update to add links to it.
15:00:30 [nigel]
Nigel: Since we refer to this before, was it deemed to be an obvious concept or did we
15:00:33 [nigel]
.. inherit it from SMIL?
15:00:45 [nigel]
Glenn: I don't recall inheriting it from SMIL, but our usage would be different anyway.
15:00:52 [nigel]
Cyril: Timed Element is a concept in SMIL I think.
15:01:05 [nigel]
Glenn: It could be but the glossary section is very weak. In any case now that we have
15:01:16 [nigel]
.. introduced timed element we should link those 16 places back to the definition now that
15:01:19 [nigel]
.. we've added a term.
15:01:20 [nigel]
Nigel: +1
15:02:08 [nigel]
Nigel: Notices we should take care with 12.4
15:02:34 [nigel]
Glenn: Yes
15:02:41 [nigel]
Nigel: Aside from that, I think this looks good.
15:03:00 [nigel]
SUMMARY: @skynavga to update to include references to the timed element term, then review to continue.
15:03:02 [nigel]
github-bot, end topic
15:03:26 [nigel]
Topic: Clarify distinction between validation processing, validation process… ttml2#777
15:03:31 [nigel]
github: https://github.com/w3c/ttml2/pull/777
15:03:50 [nigel]
Glenn: I did a commit last night in which I think I addressed Nigel's comments.
15:03:53 [glenn]
https://github.com/w3c/ttml2/pull/777/commits/4aaf65d902fc70f374e31751074a18d26389f6f2
15:04:57 [nigel]
Nigel: [reviews in real time] Looks good to me.
15:05:28 [nigel]
.. I've approved.
15:05:44 [nigel]
SUMMARY: Pull request satisfies merge requirements.
15:06:04 [nigel]
Topic: Collapse language for style application to paragraph text nodes; add … ttml2#803
15:06:10 [nigel]
github: https://github.com/w3c/ttml2/pull/803
15:06:39 [nigel]
Glenn: I added a comment to this.
15:09:17 [nigel]
Cyril: Can we add a link from the sentence in 8.1.5 to the process for creating anonymous spans?
15:09:33 [nigel]
Glenn: Yes, and come to think of it we should add the same text to the span element to
15:09:37 [nigel]
.. make it complete. Right now it is incomplete.
15:10:31 [nigel]
Cyril: I don't want it to look like there's a separate procedure.
15:10:41 [nigel]
Glenn: That gives me a tbd on this before you sign off on it Nigel
15:10:44 [nigel]
Nigel: OK
15:12:31 [nigel]
.. Should we add a note pointing the reader to anonymous spans beneath the new text?
15:12:56 [nigel]
Glenn: I don't want another place where we paraphrase what the construct anonymous span
15:12:58 [nigel]
.. procedure does.
15:13:07 [nigel]
Nigel: I was thinking of a note with a reference, but I take your point.
15:13:36 [nigel]
Glenn: The terms anonymous span and span already take you to the right definitions.
15:13:54 [nigel]
Nigel: Yes, if you add that anonymous span text from p to span then yes, I'm okay with that.
15:14:43 [nigel]
SUMMARY: Duplicate anonymous span text from p element into span element (for @skynavga) and reference the [create anonymous span] procedure from both.
15:15:02 [nigel]
Topic: Add xml:base to core vocabulary (#804). ttml2#808
15:15:07 [nigel]
github: https://github.com/w3c/ttml2/pull/808
15:15:27 [nigel]
Glenn: This adds `xml:base`. Previously in TTML1 the `features` and `extensions` elements
15:15:41 [nigel]
.. admitted `xml:base` and those were unusual in that we defined a default value in the
15:16:01 [nigel]
.. element information item that specifies using the TTML feature namespace and the extensions
15:16:17 [nigel]
.. namespace respectively. Those were kind of special uses that had a default.
15:16:29 [nigel]
.. This PR and issue is for, now that we have URLs in a variety of other places such as
15:16:51 [nigel]
.. xlink:href and the source element and audio, data and image, we potentially have some
15:17:14 [nigel]
.. uses that are related to the media query support in the condition function for media functions,
15:17:41 [nigel]
.. my conclusion was we need to add `xml:base` to the core attributes list so it is everywhere.
15:18:00 [nigel]
.. Now `xml:base` is hierarchical so you can have multiple relative levels. It can build up
15:18:17 [nigel]
.. hierarchically from the most nested reference to the root level element. You need to
15:18:31 [nigel]
.. populate it everywhere (ability to populate).
15:18:49 [nigel]
.. Especially if you're embedding content that has some URLs in it you might nest that in
15:19:05 [nigel]
.. another document and put a relative base on it at the highest level node. It turns out to
15:19:14 [nigel]
.. be quite useful and is supported in SVG and SMIL as well.
15:19:50 [nigel]
Nigel: Did you fix Cyril's issue about isd:css and isd:region too?
15:20:03 [nigel]
Glenn: Yes. I know Cyril had suggested just supporting on the root level but as you see that
15:20:06 [nigel]
.. won't quite work.
15:20:20 [nigel]
Cyril: I understand the feature, I don't think it's a priority. You could default it to the base
15:20:24 [nigel]
.. of the document itself.
15:20:42 [nigel]
Glenn: That is the default default if there are relative URLs in the document with no xml:base specified.
15:20:48 [nigel]
.. We don't have to say anything to support that.
15:21:02 [nigel]
Cyril: I don't have a strong preference. It's mainly useful for images and audio content right?
15:21:07 [nigel]
Glenn: Exactly.
15:21:51 [nigel]
Nigel: I don't have strong view either, but don't have a particular use case. I don't think it
15:21:58 [nigel]
.. is especially harmful. Is there a profile feature for it?
15:22:09 [nigel]
Cyril: There is #base and #base-version-2
15:22:12 [nigel]
Nigel: Ok
15:22:13 [cyril]
https://rawgit.com/w3c/ttml2/0c93c4dfa88e85a61d1c2cf1bae9a530c1e7e25c/index.html
15:22:27 [nigel]
Glenn: I defined it that way because we already had base in TTML1 but with no feature so
15:22:40 [nigel]
.. I defined in TTML2 a feature that mapped to the original TTML1 support for base and then
15:22:45 [nigel]
.. extended it with the version-2.
15:22:49 [nigel]
Nigel: Makes sense.
15:23:29 [nigel]
Cyril: I think we should move on from this - it was opened yesterday.
15:23:42 [nigel]
.. Seems consistent, not harmful, we should approve if there's no objection. I would like
15:23:56 [nigel]
.. some input from the SMPTE image users to see if they have any views on this.
15:24:03 [nigel]
Glenn: Yes, I'm not asking for early merger on this.
15:24:14 [nigel]
SUMMARY: Offline review to continue.
15:24:16 [nigel]
github-bot, end topic
15:24:38 [nigel]
Topic: Add #unicodeBidi-version-2 feature designator (#679). ttml2#759
15:24:49 [nigel]
github: https://github.com/w3c/ttml2/pull/759
15:25:47 [nigel]
Glenn: Nigel you made a statement about this but did not approve.
15:25:58 [nigel]
Nigel: Yes, that was 2 weeks ago, pending a discussion of the approach to defining features
15:26:10 [nigel]
.. by reference to their TTML1 definition. We had that discussion and agreed to proceed
15:26:24 [nigel]
.. on that basis so I can now complete the review of this pull request.
15:27:50 [nigel]
.. [does a rescan] Looks good to me.
15:28:29 [nigel]
.. I've approved it.
15:28:54 [nigel]
SUMMARY: Pull request meets criteria for merging
15:29:13 [nigel]
Topic: Add and update element derivations (#380). ttml2#805
15:29:21 [nigel]
github: https://github.com/w3c/ttml2/pull/805
15:29:26 [nigel]
Glenn: I don't have any reviews on this yet.
15:29:39 [nigel]
Cyril: The reason I didn't review it is I don't really consider it necessary. There's no impact
15:29:43 [nigel]
.. if there's a bug in this one.
15:29:51 [nigel]
Glenn: Exactly, this is a non-normative appendix.
15:30:03 [nigel]
Cyril: I can approve it if you want but I thought Nigel was best placed to do it.
15:31:02 [nigel]
Nigel: I need more time to review this.
15:31:21 [nigel]
Glenn: That's fine with me - I just need a review. It's an editorial pull request that's only 2
15:31:30 [nigel]
.. days old, so there's a day to go minimally before merge anyway.
15:32:37 [nigel]
Nigel: OK I'll take a look.
15:32:44 [nigel]
SUMMARY: Offline review to continue
15:32:49 [glenn]
https://github.com/w3c/ttml2/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+milestone%3ACR2+-label%3A%22pr+open%22
15:32:49 [nigel]
github-bot, end topic
15:33:23 [nigel]
Topic: CR2 issues with no pr open label on them
15:33:29 [nigel]
-> https://github.com/w3c/ttml2/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+milestone%3ACR2+-label%3A%22pr+open%22
15:33:37 [nigel]
Glenn: I've marked a couple of them for agenda
15:34:31 [nigel]
Topic: Time containment semantics for smpte time base. ttml2#377
15:34:39 [nigel]
github: https://github.com/w3c/ttml2/issues/377
15:34:55 [nigel]
Glenn: Nigel, you're original complaint was that we prematurely deprecated the use of
15:35:16 [nigel]
.. the sequential time containment in smpte discontinuous mode and you have argued that
15:35:29 [nigel]
.. there is a potential interpretation of that. I argue that even if that is the case then it
15:35:38 [nigel]
.. doesn't make any sense to use it and it shouldn't be used anyway.
15:36:05 [nigel]
.. In my mind smpte discontinuous indicates that there is no time container at all.
15:36:18 [nigel]
Nigel: I don't think there's no time containment.
15:36:42 [nigel]
Glenn: For example if you have a span in a p and the span says begin=0s and the p says begin=10s
15:36:57 [nigel]
.. for me the 0s on the begin relates to the document timeline not to the p.
15:37:32 [nigel]
.. Any time you find a time in a smpte discontinuous document then it relates to the
15:37:58 [nigel]
.. document context. This is from markerMode. The problem with what you're suggesting
15:38:24 [nigel]
.. Nigel is that it backs out that. Under markerMode it says that time expressions must not
15:38:46 [nigel]
.. be calculated etc. in discontinuous mode. All time expressions are interpreted as time
15:39:01 [nigel]
.. events which cause a temporal interval to begin or end accordingly.
15:42:33 [nigel]
Nigel: I don't disagree with that but my point is that time expression calculation is orthogonal
15:44:18 [nigel]
.. to time containment, and that there is a logical processing model for sequential time
15:45:22 [nigel]
.. containment with smpte discontinuous, treating the time expressions as events.
15:45:39 [nigel]
.. I don't believe that there is any data presented to deprecate this potential usage.
15:45:56 [nigel]
Glenn: If we take out the deprecation, I don't really want to tweak this language or add
15:46:27 [nigel]
.. more language?
15:47:42 [nigel]
Nigel: I don't think we need to do anything particular to the spec and I wouldn't prioritise
15:48:08 [nigel]
.. this niche use case, just back out the deprecation.
15:48:12 [nigel]
Glenn: Is this editorial?
15:48:28 [nigel]
Nigel: Although we apparently did not have consensus for this when #647 was merged
15:48:44 [nigel]
.. in February, this is a substantive change relative to CR1 unfortunately.
15:48:55 [nigel]
Glenn: Okay I can accept backing out the deprecation, I may ask for early merge next week.
15:49:49 [nigel]
SUMMARY: Back out the deprecation of seq time containment in smpte discontinuous
15:50:31 [nigel]
Topic: Negative feature designators aren't future proof. ttml2#697
15:50:36 [nigel]
github: https://github.com/w3c/ttml2/issues/697
15:50:40 [nigel]
Nigel: I still have the action on this.
15:50:51 [nigel]
Glenn: To some extent #794 overtakes this because we are already backing out some
15:51:04 [nigel]
.. negative feature designations. I'm not sure if there are potential action items.
15:51:15 [nigel]
Nigel: Let me keep it and think further on this please.
15:52:14 [nigel]
.. The action on me is to demonstrate that there is a specific problem.
15:52:31 [nigel]
Glenn: The only remark I have is that one of the reasons we use the phrase "all defined values"
15:52:44 [nigel]
.. is that not all values are enumerable, e.g. floating point values, and the primary condition
15:52:58 [nigel]
.. expressions are infinite in their number of possibilities, so we can't enumerate every
15:53:01 [nigel]
.. value set.
15:53:09 [nigel]
Nigel: There are ways to group value sets finitely.
15:53:50 [nigel]
Glenn: In the condition refactoring, where you suggested using "non-function" expressions,
15:53:57 [nigel]
.. there probably isn't any other way to do it.
15:54:05 [nigel]
Nigel: Ok the action is still with me.
15:54:20 [nigel]
Glenn: My point is even if you think we'd like to do this I don't think we can completely
15:55:22 [nigel]
.. do what you're suggesting, in the case of some infinite value sets.
15:55:57 [nigel]
Topic: tts:rubyReserve length component semantics ttml2#779
15:56:02 [nigel]
github: https://github.com/w3c/ttml2/issues/779
15:56:17 [nigel]
Cyril: Glenn can you clarify that we harmonised rubyReserve with rubyPosition using
15:56:34 [nigel]
.. `<annotation-position>`? Looking at the CR spec I couldn't find it.
15:56:50 [nigel]
Glenn: There's an optional length component in rubyReserve.
15:57:06 [nigel]
.. The set of keywords that are defined there are equal to or a subset of `<annotation-position>`.
15:57:11 [nigel]
.. We took out around and between.
15:57:35 [nigel]
Cyril: Did we change the examples?
15:58:49 [nigel]
Nigel: [checks spec] There's no mismatch between the examples in rubyReserve and the syntax.
15:58:58 [nigel]
Cyril: OK, sorry, I was looking at the wrong version.
15:59:33 [nigel]
Glenn: The example does need to be updated - around and between have gone.
15:59:42 [nigel]
Nigel: Sorry, I also looked at the wrong version.
15:59:52 [nigel]
Glenn: It looks like I just need to remove the around and between examples.
16:00:11 [nigel]
Cyril: OK, now about the behaviour or ruby, line area and lineHeight.
16:00:27 [nigel]
.. You clarified that the rubyReserve area is parented to the line area.
16:00:30 [nigel]
Glenn: Correct.
16:00:48 [nigel]
Cyril: But I remember that the CSS WG said that you also had to set the line-height and that
16:00:59 [nigel]
.. ruby-reserve did not affect the line height. Is that the case in TTML2 as well?
16:01:10 [nigel]
Glenn: I avoided going into the details of this in the spec.
16:01:15 [nigel]
Cyril: so it's implementation specific?
16:01:18 [nigel]
Glenn: Yes.
16:01:25 [nigel]
Cyril: Why don't we do the same with rubyReserve?
16:01:41 [nigel]
Glenn: TTP for example increases the line height based on the concept that the definition
16:01:52 [nigel]
.. of normal under line height maps to the per inline height rectangle in XSL-FO and that
16:02:06 [nigel]
.. is defined in such a way as to increase the line height on the per line area basis based on
16:02:19 [nigel]
.. the glyph areas contained in that so that the ascender, descender and half leadings on
16:02:31 [nigel]
.. both sides of every glyph area are included in the line height for that particular line.
16:02:46 [nigel]
.. The height of individual areas in "normal" varies based on what is inside them. The model
16:03:04 [nigel]
.. there is to extend the line height to enclose the descendants. I use the same model, if
16:03:18 [nigel]
.. lineHeight="normal" (including default) it will increase the line height of a box that has
16:03:32 [nigel]
.. ruby to include the ruby annotation inline areas. I avoided writing this into the spec at
16:03:44 [nigel]
.. this point. One thing you are suggesting is that we add a note maybe that it is implementation
16:03:55 [nigel]
.. dependent what effect rubyReserve has on lineHeight?
16:04:06 [nigel]
Cyril: I'm not sure if that is what I am suggesting. I am trying to understand how it works.
16:04:19 [nigel]
.. If I cannot understand it probably other readers cannot understand how it works.
16:04:43 [nigel]
Glenn: Interestingly Pierre is just mapping to CSS and letting CSS do it. What I implemented
16:04:57 [nigel]
.. is basically compatible with that. CSS doesn't define those details. It's basically what is
16:05:10 [nigel]
.. implemented in the wild is the de facto standard.
16:05:17 [nigel]
.. It would take a lot of work to define those requirements.
16:05:32 [nigel]
Cyril: I'm fine with not specifying it and maybe in a future version doing that when we have
16:05:40 [nigel]
.. converged on a processing model.
16:05:58 [nigel]
.. Pierre is saying that the length field is over-specified?
16:06:04 [nigel]
Nigel: I think we need Pierre here for that.
16:06:18 [nigel]
Glenn: My interpretation is that he has some issue with how we define the default value
16:06:46 [nigel]
.. for length.
16:09:08 [nigel]
Glenn: We have the problem of length with lineHeight too, which is not dependent on font size either.
16:09:20 [nigel]
Nigel: OK so now we have the problem in two places!
16:09:38 [nigel]
.. Given the time and that this issue was raised by Pierre who is absent, we should not
16:09:41 [nigel]
.. continue with this issue.
16:09:46 [nigel]
github-bot, end topic
16:10:16 [nigel]
Topic: Use of maximum descendant font size in normal line height computation. ttml2#806
16:10:21 [nigel]
github: https://github.com/w3c/ttml2/issues/806
16:10:31 [nigel]
Glenn: I would like to spend 5 minutes on this for the record
16:10:44 [nigel]
.. The issue is lineHeight - what does "normal" mean?
16:11:00 [nigel]
.. We had some language in TTML1 that said the computed value is no less than the font
16:11:12 [nigel]
.. size that applies to the element and its descendant elements. When we recast that in TTML2
16:11:31 [nigel]
.. we inadvertently omitted mention of the descendant elements.
16:11:39 [nigel]
Nigel: No, we discussed it and decided that we didn't need it.
16:11:47 [nigel]
Glenn: Thanks for reminding me, I need to go back to the notes on that.
16:12:05 [nigel]
.. I decided to re-review the way that XSL-FO defines this, and the CSS semantics, and I
16:12:16 [nigel]
.. concluded that TTML1 semantics do not match CSS 2 or XSL-FO and TTML2 semantics
16:12:31 [nigel]
.. match none of them as defined. I marked this as a bug and something we need to deal with.
16:12:44 [nigel]
.. I was going to maybe today or tomorrow post a pull request to deal with this. The main
16:12:57 [nigel]
.. problem is that the current algorithm leads you to the conclusion that you can set a
16:13:12 [nigel]
.. uniform line height that is resolved from normal and that it applies to every line
16:13:24 [nigel]
.. irrespective of the inline areas on each line. In the XSL-FO language it says it should be
16:13:41 [nigel]
.. the minimum required to enclose the paragraph's requested line height and the line height
16:13:55 [nigel]
.. for each of the inline areas within the line area. In other words different line areas may
16:14:18 [nigel]
.. have different heights based on lineHeight="normal". The current text does not do what
16:14:23 [nigel]
.. CSS2 does or what XSL-FO says.
16:16:24 [nigel]
.. We're inconsistent.
16:16:39 [nigel]
Nigel: I recall Andreas making a presentation to us in a face to face meeting about this,
16:16:50 [nigel]
.. and pointing out that the line stacking strategy we use in TTML means that lines can
16:16:53 [nigel]
.. never overlap each other.
16:17:05 [nigel]
Glenn: I dispute that, and will have to go back and check.
16:17:27 [nigel]
.. "normal" is the most used value, and I'm pretty sure that the expectation would be the
16:17:37 [nigel]
.. same as in CSS, but that is not how it is specified now.
16:17:50 [nigel]
.. I don't know if say imsc.js would be able to do what the new language says.
16:19:45 [nigel]
Nigel: I would advocate looking for line stacking strategy and go back to where we discussed this before.
16:20:18 [nigel]
Glenn: In the case of "normal" you don't get bleed over between lines, but you might with a number.
16:20:33 [nigel]
Nigel: I thought the same line stacking strategy applies even with a number.
16:20:51 [nigel]
Glenn: If that's the case then XSL-FO would be inconsistent with CSS2. I would need to look at that.
16:22:07 [nigel]
Nigel: The line-stacking-strategy is line-height, regardless of the value of tts:lineHeight.
16:22:55 [nigel]
SUMMARY: @skynavga to continue investigating
16:22:59 [nigel]
github-bot, end topic
16:23:02 [nigel]
Topic: Meeting close
16:23:16 [nigel]
Glenn: We covered a lot today so thank you for that. I look forward to the pull request reviews.
16:23:26 [nigel]
.. #794 is my highest priority if you can take that into account.
16:23:41 [nigel]
Nigel: OK, thanks both, next meeting same time next week. [adjourns meeting]
16:23:54 [nigel]
rrsagent, make minutes
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nigel has changed the topic to: TTWG meetings Thursdays 1000 Boston time. Minutes for most recent meeting: https://www.w3.org/2018/05/31-tt-minutes.html