IRC log of tt on 2018-10-22

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Meeting: Timed Text Working Group Teleconference
06:39:53 [trackbot]
Date: 22 October 2018
06:40:01 [nigel]
06:42:27 [nigel]
Present: Glenn, Nigel, Andreas
06:42:29 [nigel]
Chair: Nigel
06:42:32 [nigel]
scribe: nigel
06:42:39 [nigel]
Topic: Agenda bash
06:43:14 [glenn]
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06:44:08 [nigel]
Nigel: Looking at our agenda:
06:44:25 [nigel]
-> TTWG TPAC Agenda page
06:44:41 [nigel]
Nigel: I don't think we will have a joint meeting with CSS WG
06:45:17 [nigel]
Andreas: Tomorrow I'd like to discuss closer alignment with CSS
06:45:28 [nigel]
Glenn: I'd like to consider TTML2 2nd Ed requirements
06:46:10 [nigel]
Nigel: We have an agenda topic for that tomorrow - I have a use case to bring also.
06:46:56 [nigel]
Andreas: For the agenda, I don't think we need anything for TTML <--> WebVTT mapping.
06:47:05 [nigel]
Nigel: Yes, we took that off the agenda already.
06:47:53 [nigel]
Nigel: Glenn asked to discuss Karaoke.
06:48:05 [nigel]
Glenn: I don't have anything prepared for that, so we can scratch that off the agenda
06:48:10 [nigel]
.. or cover it very quickly.
06:48:33 [nigel]
Andreas: There will be topics relative to the TTWG that will come up during the M&E IG,
06:48:42 [nigel]
.. like 360º VR and AR.
06:49:03 [nigel]
.. I have to be at the AC tomorrow from 3 so I will not be able to join the future requirements
06:49:05 [nigel]
.. session.
06:49:25 [nigel]
.. Can we move the future requirements to after lunch and then audio profiles later?
06:49:26 [nigel]
Nigel: OK
06:55:43 [nigel]
Andreas: I need to go to the M&E IG now, see you there later!
06:56:18 [glenn]
Note: is undergoing technical problems, see
06:56:30 [nigel]
Nigel: I will start to prepare some slides for our joint meeting with M&E IG now.
06:59:41 [nigel]
Present+ David_Singer, Pierre
07:05:09 [nigel]
Glenn: I think we need to cover WebVTT and the status
07:05:20 [nigel]
Pierre: We should discuss the TTML ballots also
07:07:13 [nigel]
.. If it helps we could walk people through the implementations
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07:20:09 [nigel]
Nigel: When should we cover WebVTT?
07:20:22 [nigel]
David: My feeling now is that we won't get enough input to get to PR and Rec so we
07:20:32 [nigel]
.. should leave it there and propose that we drop the work and publish as a WG Note.
07:20:48 [nigel]
.. If nobody comes forward to say "I'm willing to do the work" then we should go with
07:20:50 [nigel]
.. that proposal.
07:21:05 [nigel]
Nigel: Do we need an agenda topic to take that any further?
07:23:04 [nigel]
David: I will check if anyone else from Apple is likely to attend today or tomorrow.
07:23:49 [nigel]
Nigel: The main body of our meeting is tomorrow - I have prepared some material for
07:24:10 [nigel]
.. the discussion on live subtitle topic.
07:24:22 [nigel]
Pierre: If the group decides to tackle this, the first step should be for the WG to accept
07:24:30 [nigel]
.. the system model, as the basis for the work.
07:24:31 [nigel]
Nigel: +1
07:25:08 [nigel]
Pierre: I think there's real confusion about the production process vs the "broadcast encoder"
07:25:24 [nigel]
.. for want of a better term. Once it hits ISOBMFF, what happens, for example? Does
07:25:35 [nigel]
.. anything special have to happen after the emission encoder or is it really upstream.
07:25:51 [nigel]
.. Even if we could publish a Note and tell people to look for it before asking questions
07:25:55 [nigel]
.. that would be helpful.
07:26:26 [nigel]
Nigel: I feel I will be able to answer that question!
07:34:46 [nigel]
David: On the WebVTT proposal, I will take an action to send a note to the mailing list
07:35:43 [nigel]
.. explaining the proposal. If we get no response we should take silence as assent.
07:49:41 [nigel]
Topic: M&E IG joint meeting preparation
07:49:45 [nigel]
Nigel: [bashes presentation deck for joint M&E IG]
07:51:28 [nigel]
Pierre: For future requirements for TTML, it would be useful to think about the language
07:51:43 [nigel]
.. in the core about style attributes, and allowing for additional modules.
07:52:02 [nigel]
Glenn: If we have modules that try to apply diffs to the core, that becomes messy.
07:52:14 [nigel]
Pierre: Maybe we would choose not to support that, but to support plugins for example
07:52:27 [nigel]
.. new style attributes that participate in the style resolution algorithm.
07:54:52 [nigel]
Glenn: I don't know if anyone wants to discuss 3D and adding a z-value dimension to
07:54:55 [nigel]
.. text positioning.
07:55:57 [nigel]
Glenn: I'm having a conversation about future requirements concerning a DOM API
07:56:16 [nigel]
.. for TTML, from an organisation interested in translation and localisation.
07:56:32 [nigel]
.. It would be to support Javascript processing of TTML for example.
07:56:46 [nigel]
.. Perhaps that's the conceptual model that the organisation I'm talking to has in mind.
08:05:20 [nigel]
Nigel: I've uploaded that to
08:09:32 [nigel]
Topic: TTML Profile Registry issues
08:09:41 [nigel]
Nigel: Given that GitHub is down, this may not work too well...
08:09:58 [nigel]
.. I can see we have some new issues.
08:10:46 [nigel]
Glenn: Nigel had a question about #52
08:11:08 [nigel]
.. It's a portmanteau issue where the details will be in the Pull Request
08:11:21 [nigel]
Nigel: Please don't do that - you're asserting there's something wrong with the text
08:11:43 [nigel]
.. and planning to go ahead with a pull request before getting any discussion that
08:11:58 [nigel]
.. concurs with your review. Be prepared to get push back from the WG on that.
08:12:02 [nigel]
Pierre: But what is wrong with the text?
08:12:18 [nigel]
Glenn: For example Respec complains about a normative reference in a non-normative section.
08:12:23 [nigel]
.. Another is inconsistent capitalisation.
08:12:29 [nigel]
Pierre: OK, editorial things.
08:12:37 [nigel]
Glenn: I'll throw them in the summary to help with review.
08:12:44 [nigel]
Pierre: Are there any non-editorial issues?
08:12:59 [nigel]
Glenn: If there are then I will open a separate issue for them.
08:13:12 [nigel]
.. There's also some language in the prologue to the media registration part that talks
08:13:26 [nigel]
.. about plans for sending to IANA but we have already done that so it no longer applies.
08:13:34 [nigel]
.. It can either be removed or truncated.
08:13:44 [nigel]
.. The biggest change I'm going to propose is changing §4.2 to informative. I'm not sure
08:13:55 [nigel]
.. how it got in there, I wasn't paying attention apparently. It's quite problematic.
08:14:04 [nigel]
.. It purports to describe how to resolve the profile of a document.
08:14:14 [nigel]
Pierre: That was before TTML2
08:14:20 [nigel]
.. We should just fix it.
08:15:28 [nigel]
Glenn: I'm willing to keep it in as an informative section.
08:15:41 [nigel]
Nigel: It precedes TTML2 and the referenced specifications describe their own ways of
08:15:56 [nigel]
.. identifying the document instance's profile. In that sense it is informative because it's
08:16:01 [nigel]
.. a gathering of other information.
08:16:10 [nigel]
Pierre: One possibility is to remove §4.2 - that would be my preference.
08:16:16 [nigel]
Glenn: That would be my preference too.
08:16:31 [nigel]
Pierre: This is trying to be helpful, I understand.
08:16:55 [nigel]
David: It seems like a good answer to help people derive what profile a TTML document instance is.
08:16:58 [nigel]
.. It should be informative.
08:17:07 [nigel]
Glenn: The trouble is that it is not what TTML1 or TTML2 says.
08:17:16 [nigel]
David: It shouldn't be wrong!
08:17:32 [nigel]
Pierre: Right, it is possible to summarise, and should not be too much trouble, to say
08:17:43 [nigel]
.. where to look at in a TTML document instance to find what kind of thing it is.
08:17:56 [nigel]
Glenn: I don't even mind suggesting one possibility of using XPath. Maintaining this
08:18:02 [nigel]
.. data is not part of the registry.
08:18:06 [nigel]
Pierre: And its wrong!
08:18:11 [nigel]
Nigel: Is it?
08:18:24 [nigel]
Pierre: Yes, especially in TTML2 you have precedence rules about content profile, profile
08:18:27 [nigel]
.. attribute...
08:18:36 [nigel]
Glenn: profile override, outer context...
08:18:38 [nigel]
Pierre: yeah
08:19:16 [nigel]
Glenn: For example for tt1t it doesn't refer to what TTML1 or TTML2 does.
08:20:01 [nigel]
Nigel: The XPath thing doesn't say you must use XPath.
08:20:17 [nigel]
Pierre: IMSC does not use this technique for deciding if a document is IMSC compatible for instance.
08:20:30 [nigel]
Glenn: I don't know of any implementation that uses this technique.
08:20:44 [nigel]
Pierre: I would replace it with a more descriptive prose section.
08:21:01 [nigel]
David: It is useful to help find what kind of TTML document instance you have in front of you.
08:21:05 [nigel]
.. What the document claims to be.
08:21:22 [nigel]
Pierre: You can validate any document against any profile to see if it valid.
08:21:30 [nigel]
David: You need to know what a document claims conformance to.
08:21:44 [nigel]
Glenn: You're conflating content profile vs processor profile.
08:21:50 [nigel]
Nigel: I didn't hear that from David.
08:22:34 [nigel]
David: It seems like a reasonable question to ask what a document claims conformance to.
08:22:47 [nigel]
Glenn: It's out of place in the registry because the codecs profile does not refer to content profiles.
08:22:50 [nigel]
Nigel: That's true.
08:24:42 [nigel]
.. I would maybe rewrite it and put it in an appendix rather than have it in §4.2.
08:25:00 [nigel]
David: The codecs parameter is useful and you need to know how to specify it based on a document
08:25:15 [nigel]
Nigel: Subtle distinction: it's about knowledge of the document, not the document itself.
08:25:27 [nigel]
.. It may be that you know a doc is EBU-TT-D and IMSC but the document doesn't make
08:25:40 [nigel]
.. any claim internally. You can set codecs based on that.
08:25:53 [nigel]
Glenn: You also may know you don't need full processor support for every feature.
08:26:38 [nigel]
.. By the way the document doesn't set a precedence order for profile vs codecs
08:26:43 [nigel]
David: Why is it called codecs?
08:26:48 [nigel]
Pierre: So it can be used in MP4
08:26:55 [nigel]
David: You can copy the codecs value across?
08:26:58 [nigel]
Pierre: Yes
08:27:31 [glenn]
github outage incident report:
08:27:38 [nigel]
Nigel: This is what goes after stpp.
08:27:52 [nigel]
David: It's the sub-parameter for the codecs? Got it.
08:28:22 [nigel]
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08:28:35 [nigel]
Glenn: My action is I plan to make a PR for this based on the input I've heard today.
08:28:46 [nigel]
.. Instead of removing it entirely I'll take the approach that Pierre suggests, to try to
08:28:54 [nigel]
.. summarise it, and add a statement that it's a non-normative section.
08:29:03 [nigel]
Nigel: I would consider moving it to an appendix too.
08:29:14 [nigel]
Glenn: That would be my preference too. I may leave behind a pointer.
08:29:18 [nigel]
Nigel: I don't think that's needed.
08:31:42 [nigel]
Nigel: It would be useful to merge #43 before you do a pull for #53 Glenn
08:31:57 [nigel]
Glenn: I agree, please can we merge them soon?
08:32:28 [nigel]
Nigel: Any objections to merging the open pull requests?
08:32:41 [nigel]
Glenn: We will probably end up tweaking the result of that to deal with other issues.
08:32:50 [nigel]
Nigel: I'm not hearing any objections.
08:33:09 [nigel]
.. Please note Mike is the editor here and wants to continue with that.
08:33:20 [nigel]
Pierre: Just create a pull request and Mike can be in charge of merging it.
08:33:44 [nigel]
Nigel: Will you do the pull to add TTML2 profiles Glenn?
08:33:57 [nigel]
Glenn: Yes, and for #38 (Content Profiles vs Processor Profiles) too.
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08:35:24 [nigel]
Nigel: That's all on this topic. I propose we take a break and then join the M&E IG for
08:35:27 [nigel]
.. the rest of the day.
08:35:32 [nigel]
Glenn: I'm going to join that later.
08:35:38 [nigel]
Nigel: Okay!
08:35:56 [nigel]
Topic: Break, then Media and Entertainment IG.
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