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15:00:17 <trackbot> Zakim, this will be TTML
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15:00:18 <trackbot> Meeting: Timed Text Working Group Teleconference
15:00:18 <trackbot> Date: 09 March 2017
15:00:47 <nigel> Chair: Nigel
15:00:50 <nigel> Present: Nigel
15:00:52 <nigel> Regrets: Mike
15:00:56 <nigel> scribe: nigel
15:02:23 <nigel> nigel has changed the topic to: TTML meeting beginning at 1500 UTC
15:03:08 <nigel> Present+ Dae
15:05:15 <nigel> Present+ Pierre, Andreas
15:07:20 <atai> atai has joined #tt
15:07:31 <nigel> Topic: This meeting
15:08:40 <nigel> Nigel: We have one main issue to discuss for IMSC, though Mike sent his regrets.
15:08:46 <nigel> Andreas: I won't be able to join next week.
15:09:00 <nigel> Nigel: Okay lets get the views from here then and discuss it briefly without fully concluding
15:09:06 <nigel> .. until Mike has been able to contribute.
15:09:35 <nigel> Nigel: That's all on IMSC. On TTML2 we have a number of issues to cover.
15:10:18 <nigel> Nigel: I don't think there are any other main agenda topics, I can give an update under AOB
15:10:24 <nigel> .. on my trip to CSUN last week.
15:10:55 <nigel> .. There's been some progress on moving WebVTT to the next working draft but I don't
15:11:11 <nigel> .. think that's an agenda item for us today. You'll have seen David's encouragement by email
15:11:24 <nigel> .. to review and look at the dispositions.
15:11:57 <nigel> .. Any other business, or specific points to raise?
15:12:37 <nigel> Dae: For IMSC 1.next we are introducing fillLineGap? Will this carry forward to TTML2?
15:12:49 <nigel> Nigel: Yes we need the semantic in TTML2, and I believe that Glenn has begun some work
15:13:25 <nigel> .. on it in TTML2.
15:13:32 <nigel> Dae: There's no support for it in CSS yet though?
15:13:38 <nigel> Nigel: No, I did raise an issue on CSS.
15:14:18 <nigel> Present+ Thierry
15:14:20 <tmichel> present+
15:15:25 <nigel> Pierre: I started a wiki listing CSS features that are needed for subtitles. I encourage us to
15:15:27 <nigel> .. lobby for this.
15:15:34 <nigel> Nigel: +1
15:15:45 <nigel> Present+ Glenn
15:16:18 <atai> q+
15:16:47 <nigel> ack atai
15:17:02 <nigel> Andreas: A question for Nigel as BBC representative: It's clear that BBC guidelines have a
15:17:13 <nigel> .. clear requirement documented for this feature. Could this be brought to the awareness
15:17:29 <nigel> .. of the CSS WG? I think it is nowhere more obvious than in the BBC guidelines. It is just
15:17:37 <nigel> .. an example but you made a strong point for it too.
15:17:45 <nigel> Nigel: Yes absolutely, very happy to do that.
15:18:13 <nigel> -> https://github.com/w3c/imsc/wiki/TTML2-features-for-inclusion-in-IMSC2
15:18:48 <nigel> Pierre: That's the list of TTML2 features for inclusion in IMSC2.
15:19:02 <nigel> Nigel: There's no pointer to which features are or are not doable in CSS?
15:19:19 <nigel> Pierre: No, I started doing that with textEmphasis but I haven't with anything else.
15:19:50 <nigel> .. I can help with the mapping but ultimately Glenn is the expert there in terms of TTML2,
15:19:56 <nigel> .. so it requires his participation.
15:20:33 <nigel> Glenn: If you're talking about CSS mapping I have no interest in doing that.
15:20:47 <nigel> Dae: I don't mind volunteering to take a first go at this because most of the features have
15:21:01 <nigel> .. a straightforward mapping or fallback. I wonder how robust the fallback has to be?
15:22:14 <nigel> Glenn: My solution to mapping to HTML is to map to SVG in HTML.
15:23:15 <nigel> Nigel: To an extent that does not fully resolve the problem since CSS affects the presentatoin
15:23:27 <nigel> .. of text in SVG in any case and may be used to make it more accessible.
15:23:35 <nigel> s/oin/ion
15:23:53 <nigel> Glenn: I don't recognise that, metadata can be added to SVG to make it accessible.
15:27:06 <nigel> Nigel: Since IMSC2 is a subset of TTML2 then any features that we want to be in IMSC2 need
15:27:28 <nigel> .. to be in TTML2. If we need IMSC2 to be mapped to CSS then we need to make sure the
15:27:32 <nigel> .. fallbacks and limitations are clear.
15:28:26 <nigel> Glenn: We decided some time ago to make HTML/CSS mapping orthogonal to TTML2
15:28:29 <nigel> .. development.
15:28:52 <nigel> Dae: I will aim to do a first draft of the CSS mapping before next week's meeting.
15:29:08 <nigel> Glenn: I don't disagree that it is useful to know where the challenges are. If there are tweaks
15:29:21 <nigel> .. that can be made to make things a little easier I don't generally object to doing that.
15:30:52 <nigel> Nigel: We need to pragmatic here - if we are forced to wait for a normative reference to
15:31:03 <nigel> .. a CSS spec for everything then we will be waiting for a long time.
15:31:10 <nigel> Dae: I think this is about a fallback in some cases.
15:31:20 <nigel> Pierre: For example what is the CSS equivalent of fontShear?
15:31:26 <nigel> Glenn: There is none.
15:31:31 <nigel> Pierre: We should note it then.
15:31:49 <nigel> Glenn: We have not done that in the past. For example in TTML1 XSL-FO does not support
15:32:04 <nigel> .. all the semantics, and there's a note that declares that such unmappable semantics exist.
15:32:21 <nigel> .. We did not let that gate us for TTML1.
15:33:11 <nigel> Pierre: In the scope of IMSC1 features there is in fact a clear mapping via XSL-FO to CSS.
15:33:27 <nigel> .. XSL says what the differences are between it and CSS. That's the case for TTML1 now and
15:34:00 <atai> q+
15:34:17 <nigel> Pierre: it made the mapping clear and easy to do.
15:34:36 <nigel> Glenn: It's under §9.3.3 under synchronic flow processing, a note about there being no
15:34:45 <nigel> .. XSL counterpart.
15:35:25 <nigel> Glenn: We've had to go beyond XSL-FO and CSS in TTML2 due to new requirements that
15:35:31 <nigel> .. still are not satisfied in CSS land.
15:35:35 <nigel> ack atai
15:35:50 <nigel> Andreas: What we need to acknowledge is that since TTML1 started as a standard the
15:36:03 <nigel> .. importance of CSS mapping has increased in general in the domain and for members and
15:36:18 <nigel> .. for W3C. For IMSC1 and IMSC2 there may be the situation where the industry will not
15:36:31 <nigel> .. support a feature without a clear CSS mapping, so I can support that for everything we
15:36:32 <pal> pal has joined #tt
15:36:34 <pal> q+
15:36:44 <nigel> .. want to include especially in IMSC we should do everything we should do to make it
15:36:49 <nigel> .. work with web technology.
15:37:03 <nigel> ack pal
15:37:33 <nigel> Pierre: Are you opposing doing the mapping work Glenn?
15:37:43 <nigel> Glenn: I am not opposing it, I just don't think it is a necessary part of TTML2 and can be
15:37:46 <nigel> .. done elsewhere.
15:38:02 <nigel> Pierre: So you will not object to that or to PRs on TTML2?
15:38:15 <nigel> Glenn: Sure, I will consider PRs on TTML2.
15:38:26 <nigel> .. The other question that is deeper is that during that mapping process there may be a
15:38:38 <nigel> .. suggestion to make changes in TTML2, and that's reasonable, but we have to ask ourselves
15:39:04 <nigel> .. the practical question if waiting for that to be completed could become a blocking or gating factor for wide review.
15:39:17 <nigel> .. If during the WR process progress is made on this then we can look at that and decide
15:39:26 <nigel> .. if we want to make any changes as we come to CR to accommodate that.
15:39:57 <nigel> Nigel: [draws this discussion to a close]
15:40:21 <nigel> Topic: IMSC
15:40:29 <nigel> -> https://github.com/w3c/imsc/issues/213
15:41:24 <nigel> Nigel: I am not sure what the outstanding points are with this that need to be discussed.
15:41:35 <nigel> Andreas: I think the last edit from Pierre would be fine. Nigel you brought in an extra
15:41:52 <nigel> .. issue which is how far you give a recommendation or requirement for how far foreign
15:42:04 <nigel> .. namespace content should be defined. My view is this is not in scope of IMSC or TTML
15:42:48 <nigel> .. so would not be necessary, but it is just a recommendation so I wouldn't object to it.
15:43:40 <nigel> Nigel: It's even weaker than that - it's an informative note only to say that it is a good idea
15:43:55 <nigel> .. to define a content specification but I agree that we cannot force people to make good
15:43:57 <nigel> .. implementations!
15:44:09 <nigel> .. It's in a pull request:
15:44:11 <nigel> -> https://github.com/w3c/imsc/issues/217
15:44:24 <nigel> Pierre: Now Mike has told me he wants to be specific about exactly which elements
15:44:35 <nigel> .. support foreign namespace elements and which do not, but I do not want to rewrite
15:44:37 <nigel> .. TTML1!
15:45:02 <nigel> Nigel: There are 3 new things since last time:
15:45:10 <nigel> .. 1. If we should remove the exception for the tt element?
15:46:08 <nigel> .. 2. Clarify that foreign namespace attributes are permitted on all TTML1 elements.
15:46:49 <atai> q+
15:47:52 <nigel> Nigel: 3. Add an informative note about good practice for content specification.
15:48:10 <nigel> Pierre: I think there's a dispute that has not been resolved where Mike wants to introduce
15:48:17 <nigel> .. consideration of XML Schema validation.
15:48:25 <nigel> Nigel: I think that's further than we should go.
15:48:27 <nigel> ack atai
15:48:43 <nigel> Andreas: First I thought we do not need to be as specific as in TTML1 but now when I look
15:48:58 <nigel> .. at it maybe it would be good to document it wherever it is, because for example
15:49:14 <nigel> .. <style> does not allow <tt:metadata> as a child element, which differs from what the
15:49:27 <nigel> .. EBU group does, and has done for years, so there are people making mistakes on this.
15:49:52 <nigel> Pierre: So you're supporting Mike's idea of explicitly listing the elements where metadata
15:49:54 <nigel> .. is permitted?
15:50:08 <nigel> Andreas: I can understand not wanting to put too much in the IMSC spec but somewhere
15:50:12 <nigel> .. it should be documented.
15:50:24 <nigel> Pierre: My reluctance is simply that it requires interpretation of TTML1, which I typically
15:50:36 <nigel> .. recommend we don't do, but if we feel it is useful and Mike thinks so then maybe it
15:50:39 <nigel> .. is enough.
15:51:59 <nigel> Nigel: I really like the way it is done now by referring to Table 3 in TTML1.
15:52:11 <nigel> Pierre: It is wrong though because for example <head> permits metadata. Maybe we should
15:52:18 <nigel> .. for simplicity just list the elements directly.
15:52:51 <nigel> Nigel: OK, I'm fine with listing in an informative note the elements. That's probably a service
15:52:53 <nigel> .. to the world.
15:53:01 <nigel> Pierre: In that case I'm happy to do it.
15:54:15 <nigel> Nigel: The second point is to be clear that foreign namespace attributes are permitted on
15:54:18 <nigel> .. all TTML1 elements.
15:55:10 <nigel> Nigel: I think if we are going to summarise what TTML1 permits we should do it accurately.
15:55:21 <nigel> .. I went to the trouble of checking TTML1 and in fact every element defined in that spec
15:55:25 <nigel> .. permits foreign namespace attribtues.
15:55:32 <nigel> s/btue/bute
15:55:57 <nigel> Pierre: The risk is that people should go and read TTML1.
15:56:15 <nigel> Glenn: I agree that we should not paraphrase TTML1, it's okay to have a generic note saying
15:56:19 <nigel> .. to see TTML1.
15:56:59 <nigel> Nigel: Summarising, there's a concern that we should not list things that are defined in TTML1.
15:57:33 <nigel> .. For me, I think we should either summarise correctly or not at all.
15:57:39 <nigel> Pierre: I think you and Mike are agreed on that.
15:57:51 <nigel> .. I will list all the elements that permit foreign namespace metadata and change the lsit
15:58:04 <nigel> .. of elements in TTML1 that permit foreign namespace attributes.
15:58:23 <nigel> Nigel: Moving on to the note about content specifications, the note I have added is:
15:58:27 <nigel> .. "For validation purposes it is good practice to define and use a content specification for all foreign namespace elements and attributes used within a Document Instance. "
15:59:51 <nigel> .. The reason I think we should do this is from going back to the text in TTML1 about
16:00:05 <nigel> .. validation, you may end up with non-pruned foreign namespace elements that should
16:00:21 <nigel> .. be validated against a content specification, and this provides a small hint to plug that gap.
16:00:39 <nigel> Andreas: I will not object, but I would prefer not to do this. It could be good practice also
16:00:45 <nigel> .. to ignore unexpected content.
16:01:52 <nigel> Pierre: I will add that paragraph, update the PR. If Mike is happy then we go ahead. If not then maybe the solution is to remove that paragraph.
16:02:37 <nigel> .. if that also satisfies Mike.
16:02:48 <nigel> Nigel: Ok I wouldn't object to that if it gets us to consensus.
16:03:19 <atai> atai has left #tt
16:03:55 <nigel> Nigel: OK that's all for IMSC, let's take 2 minutes and come back for the next hour on TTML.
16:03:59 <nigel> rrsagent, make minutes
16:03:59 <RRSAgent> I have made the request to generate http://www.w3.org/2017/03/09-tt-minutes.html nigel
16:08:42 <nigel> Topic: TTML
16:09:05 <nigel> Dae: I'd like to clarify if we are addressing horizontal review comments before CR?
16:09:42 <nigel> Glenn: When I made that comment I did not plan to have to resolve all HR comments prior
16:09:55 <nigel> .. to going to WR. I did not mean I would not address them if possible. I think it is still an
16:10:27 <nigel> .. open issue about if we need to resolve them prior to going to WR.
16:10:47 <nigel> Nigel: We will need to make a call when we want to resolve to publish the WR for WD.
16:10:52 <nigel> Pierre: I recommend assigning issues.
16:11:07 <nigel> Glenn: I don't object to assigning issues to get more people working on them however I
16:11:32 <nigel> .. will need to do the merge so that will depend on the effort I have to do the editorial tasks.
16:12:12 <nigel> .. I have no objection to others preparing PRs. I might delegate the merge task to others if
16:12:22 <nigel> .. time is limited. I need to have oversight on the final text.
16:15:14 <nigel> Nigel: I don't think we should have a blanket policy on pushing all HR issues out to after WR.
16:15:23 <nigel> .. We need to be able to take it on a case by case basis.
16:15:37 <nigel> Pierre: For issue 233 on HDR that's a blocking issue for Movielabs.
16:15:43 <nigel> .. I'm happy to prepare a PR for it.
16:15:46 <nigel> Glenn: Sure.
16:16:00 <nigel> -> https://github.com/w3c/ttml2/issues/233
16:16:29 <nigel> Pierre: I will prepare a PR for that.
16:16:46 <nigel> Nigel: I expect a BBC proposal also, for the non-absolute luminance case.
16:16:54 <nigel> .. I've assigned that issue to you and me, Pierre.
16:17:40 <nigel> Dae: If anyone else feels there is a specific issue that we must resolve as soon as possible
16:17:46 <nigel> .. then it would be good to make that known.
16:18:13 <nigel> Pierre: Assigning issues is an approach that works well, where the assignee needs to propose
16:18:17 <nigel> .. a disposition.
16:18:35 <nigel> Nigel: By the way I have one, the audio description one:
16:18:37 <nigel> -> https://github.com/w3c/ttml2/issues/195
16:19:15 <nigel> Pierre: We need to document any deferred issues and agree them in the group based on the rationale.
16:20:35 <nigel> Nigel: On the AD issue I have done the pre-editing work to define the semantics and Glenn
16:20:40 <nigel> .. is in progress on the editing.
16:20:54 <nigel> Pierre: For the TTML1 issues that flow into TTML2 also then in my view they all must be
16:21:01 <nigel> .. resolved. They're bugs.
16:21:10 <nigel> Glenn: I have probably different criteria for bugs.
16:21:19 <nigel> Pierre: There are a bunch of "discussed and agreed" issues.
16:21:30 <nigel> Glenn: They're well up on my priority list and I'm trying to get through them whether they
16:21:36 <nigel> .. are labelled as bugs or not.
16:27:48 <nigel> Glenn: I'm working on the 58 issues marked TTML2WR but I have no objection to anyone
16:27:57 <nigel> .. else assigning themselves to an issue.
16:28:34 <nigel> Pierre: An efficient solution is not to ignore issues and respond to them sooner otherwise
16:28:50 <nigel> .. things will get worse in the future and people might get angry.
16:29:45 <nigel> Glenn: I'm not trying to make any decisions for the group by the way, I'm just labelling
16:29:49 <nigel> .. what I am working on.
16:29:55 <nigel> Pierre: I have to leave now.
16:30:11 <nigel> Nigel: By the way Andreas left before the TTML agenda item too.
16:30:23 <nigel> Dae: I would like to raise the bopomofo issue
16:30:35 <nigel> -> https://github.com/w3c/ttml2/issues/253
16:31:19 <nigel> Glenn: This refers to a particular script which is used in Taiwan to annotate Chinese
16:31:31 <nigel> .. in pedagogical works. I would not expect it to be seen in subtitling except possibly in
16:31:45 <nigel> .. educational programmes for children. It is only really used when teaching children in
16:31:51 <nigel> .. Taiwan how to read Chinese.
16:33:42 <nigel> Nigel: I think we should put this on hold until Richard's request to @bobbytung gets a
16:34:02 <nigel> .. response, and act on that response when it comes. It may be that we decide this is not
16:34:19 <nigel> .. high enough on our priority list and we choose to go ahead without Bopomofo support.
16:35:33 <nigel> Nigel: I did want also to discuss the em units issue:
16:35:38 <nigel> -> https://github.com/w3c/ttml2/issues/216
16:36:31 <nigel> Glenn: On that particular issue there is an editorial point on the text which I would like to
16:36:36 <nigel> .. be opened as a new issue.
16:37:16 <nigel> .. That one wasn't an early merge.
16:38:22 <nigel> Nigel: That's strange, I commented that it was an early merge and marked as one, but the
16:38:30 <nigel> .. history doesn't show that. I'm a bit confused about that.
16:38:42 <nigel> .. It turns out that Pierre and I had similar editorial comments, so I guess we can raise those
16:38:44 <nigel> .. as new issues.
16:39:08 <nigel> Nigel: There may be some consensus on the 3D and images issue:
16:39:09 <nigel> -> https://github.com/w3c/ttml2/issues/216
16:39:14 <nigel> s/216/239
16:41:21 <nigel> Nigel: The last points by Mike, Pierre and I are that we do not need to have left/right images.
16:41:34 <nigel> Glenn: On the point about using condition I would like to add named parameters there.
16:41:43 <nigel> Nigel: I don't think that's necessary but I would not object to it.
16:41:55 <nigel> Glenn: I can do that very quickly and post a PR that does that and see what comments there are.
16:42:41 <nigel> Nigel: The only reason against doing that is if it generates additional test cases that we do
16:42:49 <nigel> .. not actually need. Otherwise I don't have a problem with that.
16:44:28 <nigel> Glenn: I'll add a comment to the effect that this is what I will do.
16:46:05 <nigel> nigel: The next issue I listed was the TTML1 pull request:
16:46:09 <nigel> -> https://github.com/w3c/ttml1/pull/233
16:46:25 <nigel> Nigel: This is one of Andreas's.
16:46:39 <nigel> Glenn: We had the whole issue of whether padding should be on the inside or the outside of regions.
16:46:54 <nigel> .. I see this is a note. I need to do more than just add this, I would need to add an errata
16:47:35 <nigel> .. info and change info, but I see you made a suggestion.
16:47:43 <nigel> Glenn: So we can mark this as discussed and agreed?
16:47:50 <nigel> Nigel: I think so.
16:47:59 <nigel> s/So/So, mutatis mutandis,
16:48:14 <nigel> Glenn: That means "the necessary changes having been made"
16:49:09 <nigel> Nigel: I've logged that on the issue.
16:53:03 <nigel> Nigel: What about the open pull request?
16:53:18 <nigel> -> https://github.com/w3c/ttml2/pull/273
16:53:30 <nigel> Dae: Richard raised issues 274 and 275 based on that.
16:53:49 <nigel> Nigel: Oh right I did not realise the relationship was there, there's no tracing in the issues or the pull request.
16:55:49 <nigel> Dae: I think there's another one too, it might not be 275.
16:56:04 <nigel> Topic: AOB
16:56:22 <nigel> Nigel: Last week I went to the CSUN annual conference on assistive technology and presented
16:56:39 <nigel> .. on AD in TTML2 (current status anyway, and desired end goal) and also on live subtitles
16:56:47 <nigel> .. in TTML via the EBU-TT Live work.
17:00:20 <nigel> .. There was a really good and engaged audience for the AD in TTLM2 talk, and in fact
17:00:34 <nigel> .. there were a number of AD talks over the conference. There turns out to be a use case
17:01:08 <nigel> .. for pan, and also for SSML for text to speech, for example to disambiguate different ways
17:01:21 <nigel> .. of processing a number like 1876 that could be a year or a number.
17:02:14 <nigel> Glenn: I do not want to embed the whole of another language into TTML2!
17:02:39 <nigel> .. Also it would be difficult where they have created new elements and put attributes on those.
17:02:54 <nigel> .. What I have done is to create new attributes only to keep it consistent with how TTML does things.
17:03:06 <nigel> .. We have very strongly avoided elaborating our element vocabulary.
17:05:29 <nigel> Nigel: Understood. Anyhow I thought it is worth mentioning this may be a good time to take advantage of the groundswell of good feeling.
17:08:07 <nigel> Nigel: Thanks everyone. [adjourns meeting]
17:08:11 <nigel> rrsagent, make minutes
17:08:11 <RRSAgent> I have made the request to generate http://www.w3.org/2017/03/09-tt-minutes.html nigel
17:12:54 <nigel> Present- tmichel
17:17:16 <nigel> s/.. done elsewhere./Glenn: done elsewhere.
17:24:10 <nigel> s/another one too/another one aside from 274
17:24:26 <nigel> s/TTLM/TTML
17:24:50 <nigel> rrsagent, make minutes
17:24:50 <RRSAgent> I have made the request to generate http://www.w3.org/2017/03/09-tt-minutes.html nigel
17:26:15 <nigel> ScribeOptions: -final -noEmbedDiagnostics
17:26:16 <nigel> rrsagent, make minutes
17:26:16 <RRSAgent> I have made the request to generate http://www.w3.org/2017/03/09-tt-minutes.html nigel