16:01:30 RRSAgent has joined #tt 16:01:30 logging to https://www.w3.org/2021/02/04-tt-irc 16:01:32 present+ 16:02:48 glenn has joined #tt 16:02:51 zakim, start meeting 16:02:51 RRSAgent, make logs Public 16:02:53 Meeting: Timed Text Working Group Teleconference 16:02:59 mike has joined #tt 16:03:13 Present: Andreas, Atsushi, Glenn, Gary, Nigel 16:03:24 Chair: Gary, Nigel 16:03:27 scribe: nigel 16:03:28 atai has joined #tt 16:03:38 Agenda: https://github.com/w3c/ttwg/issues/173 16:03:40 sorry for the nuisance, but I don't seem to have any webex coordinates for this meeting 16:03:50 Previous meeting: https://www.w3.org/2021/01/21-tt-minutes.html 16:04:38 send coords to me alsoo 16:05:50 Present+ Cyril, Pierre 16:05:58 Topic: This meeting 16:06:38 Nigel: For today, we have some TTML2 items to discuss, and I've left the 2021 workplan placeholder in. 16:06:49 .. Also switching master to main git branch names 16:07:07 .. Any other business? Or points to make sure we cover? 16:07:10 the "private channel" is not connected to me apparently... 16:09:23 Topic: TTML2 Open PRs 16:09:40 github: https://github.com/w3c/ttml2/issues/1215 16:10:03 Present+ Mike 16:10:21 Nigel: As far as I can tell we have consensus on this. 16:10:52 .. The pull request is 1216. https://github.com/w3c/ttml2/pull/1216 16:11:21 q+ 16:11:39 ack atai 16:11:51 Andreas: I looked at the discussion and the imscJS change. Looks good to me. 16:11:58 .. Clarifies what is implied, how lineHeight is computed. 16:12:07 .. When looking through I wondered, and we could discuss perhaps. 16:12:30 .. Why in 10.2.27 tts:lineHeight, there is a very detailed algorithm for "normal" and how the different properties work together, 16:12:38 .. but we don't have it for other values. 16:12:55 .. I think that was part of the confusion before. Now it is clear that fontSize applies to p, that's fine. 16:13:11 .. But in the lineHeight section it is not that clear how fontSize is used when the value is not "normal". 16:13:29 Glenn: Are you commenting on this PR or raising this issue to discuss again? I thought we had consensus on how to handle it. 16:13:42 Andreas: It's a question, not an opposition to the PR. 16:13:50 Glenn: Okay then you support the PR? 16:13:59 Andreas: I would like to discuss the question first. 16:14:32 .. It's of course related. If we fix this problem, I would like the explanation why we don't have some explanation in this section. 16:14:51 Glenn: Okay. I agree we don't say anything about the non-normal case specifically. 16:14:58 .. It isn't covered by the multi-point algorithm. 16:15:40 .. The only thing that could mean is that the semantics of line height (see the note about line stacking too) is the derivation section, 16:16:00 .. refers to XSL-FO which refers to CSS. So the only thing one can do is interpret it from that information. 16:16:20 .. There's also a statement about the intent underneath the derivation. 16:16:39 .. It discusses the idea of being compatible with XSL-FO 1.1 and CSS 2. 16:17:02 .. I interpret that intention to be that it comes from the derivation, and that's for both normal and non-normal. 16:17:04 q+ 16:17:22 .. That generally applies to many of our other properties like fontFamily, fontSize, fontWeight. 16:17:33 cyril has joined #tt 16:17:38 .. We don't go into a whole discussion of the semantics. We effectively delegate to XSL-FO as a default. 16:17:47 rrsagent, pointer 16:17:47 See https://www.w3.org/2021/02/04-tt-irc#T16-17-47 16:18:56 q+ 16:19:19 Nigel: The question that would excite me, additional to this issue and PR, is has CSS moved on from the CSS2 semantic, and what are the deltas, 16:19:24 .. and what should we do about them? 16:19:26 ack ni 16:19:27 ack pi 16:19:55 Pierre: Changing imscJS to make these attributes applicable to p, and regenerating all the text vectors, it results in sometimes 16:20:15 .. significant change, in a way that isn't always easily predictable. So the algorithm is likely not trivial. 16:20:19 ack at 16:20:22 q+ glenn 16:20:40 Andreas: The issue is really complex. It's not easy to go through XSL-FO etc and it isn't intuitive. 16:21:01 .. The PR solves this concrete implementation problem where fontSize was not applied to p and there was an undesired rendering behaviour. 16:21:06 .. The Pull Request is fine. 16:21:23 .. But in general for the general reader it is not really clear how fontSize on p is really used. 16:21:46 .. I agree with Nigel that it is a bigger problem, and again, like in writingMode, the combination of TTML, XSL-FO, CSS2 (not 2.1!) and what 16:22:06 .. CSS does now and what is used for rendering. As it seems, I think I have heard or read that on purpose it is possibly a bit weak. 16:22:22 .. It is maybe not deterministic what is going on there. For a spec it is not satisfying, but I don't have an answer. 16:22:26 ack gl 16:22:49 Glenn: To comment on it not being intuitive, I would agree wholeheartedly and I would go farther and say it is highly impractical to do 16:23:08 .. anything about it. It is such a complex piece of semantics that it is never going to be intuitive. Even if you only look at CSS this is true. 16:23:19 .. So you're asking for something we can't deliver if you want an intuitive explanation. 16:23:45 .. However historically we had information about derivation about each style property, that refers to a particular section of XSL-FO or CSS. 16:23:57 .. Nigel did a lot of work to move it into the appendix and elaborate it. 16:24:17 .. We have a normative table entry from the style to the derivation appendix information, which happens to be non-normative, 16:24:39 .. because we did not want to demand it, but in effect we do demand it. That's an area where we could entertain making the derivation 16:24:50 .. section normative in the future, because in practice we treat it as normative. 16:25:23 .. The other thing, regarding Nigel's comment about changing from CSS2 to CSS3, that is also impractical. We're so embedded to 16:25:43 .. XSL-FO semantically, which is tied to CSS2, so I think what we would have to do practically is consider on a case by case basis some specific 16:26:04 .. upgrades to semantics. But if we did that we would have to find a way to accommodate any breaking changes that would reflect in our 16:26:24 .. tests. Then we would need a migration path that does not invalidate existing content. You can't simply change that and invalidate the old 16:26:47 .. behaviour (or deprecate). It would need to be a new major version, maybe even a different namespace URI to distinguish the semantic change. 16:27:19 github-bot, end topic 16:27:54 github: https://github.com/w3c/ttml2/pull/1210 16:28:07 Topic: Draft language to address font fingerprinting mitigation (#1202). w3c/ttml2#1210 16:28:09 github: https://github.com/w3c/ttml2/pull/1210 16:29:19 Nigel: I reviewed this (opened since July), and think it is an improvement and a step on the way but maybe not the end of the changes we need. 16:29:47 Andreas: I added one comment to the pull request where the addition is to strongly recommend not to dereference external fonts. 16:29:58 .. In the current pull request it says "should consider not dereferencing" 16:30:06 .. I think the "consider" should be removed. 16:30:20 .. The reasoning is that we had a long discussion with PING, who asked for more, they wanted it normative. 16:30:27 .. It is now strong language in a non-normative section. 16:30:44 .. I think we should not weaken it more, and it would be better to say "should not do it". 16:31:02 Nigel: I think Glenn already indicated he would accept it, and I certainly would. 16:31:07 Glenn: I don't like it but I could live with it. 16:31:53 Nigel: I can't see Andreas's comment on the pull request, only my proposal. 16:32:12 Andreas: I commented it but I maybe need to complete the review. 16:32:57 Nigel: If we make that change then my change would not be needed. 16:33:37 .. I would like to merge this - any requests for more time to review? 16:33:45 group: [no requests for more time] 16:34:09 Nigel: In that case when Andreas's change has been processed we should be good to merge. 16:34:18 mike_ has joined #tt 16:34:24 SUMMARY: Andreas's proposal to be applied 16:34:28 github-bot, end topic 16:34:55 Topic: Exiting TTML2 CR 16:35:14 Nigel: I made the modifications to the IR we discussed last time. 16:35:22 .. I didn't remove the other content but that would be my next step. 16:35:45 -> https://www.w3.org/wiki/TimedText/TTML2SecondEditionImplementationReport TTML2 IR 16:37:38 Nigel: [shows new table] 16:38:10 .. For example #audio points to two tests, and has one pass per test, and I would be claiming that particular change is a pass for CR exit. 16:38:33 .. One question is: does this help? 16:38:48 .. Second question: would it be improved by subdividing further by pull request? 16:38:56 Cyril: Not sure the pull request would bring anything 16:40:23 Nigel: I am wondering if there are any other implementations we could add? 16:42:11 Pierre: I need to look in detail. I need to see what's needed and how much work it is. 16:42:24 Nigel: Note that in some cases tests are listed multiple times when they apply to multiple features. 16:43:18 Pierre: Basically all of them? 16:43:21 Nigel: Yes! 16:44:06 Pierre: Thanks. 16:44:16 Glenn: I expect to fill in the presentation for at least the Skynav implementation. 16:44:39 .. Most of those that are blank under presentation are implemented. I need to verify those and enter them into this table. 16:44:42 Pierre: Okay, thanks. 16:44:52 Glenn: That doesn't help us with the second implementation. 16:45:21 Nigel: Thanks, just wanted to share progress. 16:45:29 Topic: TTML2: Publish updated CR? 16:46:38 Nigel: Given that we have two worthwhile pull requests to merge, and it is unlikely to practically affect our exit date, 16:46:45 .. I propose to publish a new CR. 16:47:00 Glenn: Seems like a good idea. I believe all the changes since last CR are editorial. 16:47:06 Nigel: I haven't reviewed but I think that's true. 16:47:17 Glenn: I agree, and can roll it out as soon as we wrap up these current PRs. 16:47:31 .. There may be some other issues we don't have PRs for, but we can do those later. 16:47:44 Nigel: Agreed. Any other views? 16:48:00 Cyril: I'm wondering if we want to take the opportunity to mark features as at risk? 16:48:34 Nigel: We can't easily mark a feature as at risk because all the features are in TTML2 already. They're just changes to the features 16:48:42 .. and we don't have an easy way to indicate the change as being at risk. 16:48:49 Cyril: Ok I will think about it, thank you. 16:49:20 PROPOSAL: After merging the open pull requests, republish TTML2 2nd Ed CR with earliest exit date as publication date + 4 weeks. 16:49:26 Nigel: Any objections? 16:49:37 RESOLUTION: After merging the open pull requests, republish TTML2 2nd Ed CR with earliest exit date as publication date + 4 weeks. 16:49:48 Nigel: There will be our 2 week decision review period starting now. 16:50:08 Topic: Switching master to main branch names 16:50:16 Nigel: Atsushi has been preparing this. 16:50:44 Atsushi: I hope you all read my email. Most of all it is work my side, and you just need to change your local changes to be against main not master. 16:50:52 .. Change your local checkout from github. 16:50:58 Gary: Also any forks if you have them 16:51:02 Atsushi: Yes 16:51:55 glenn has joined #tt 16:51:59 Nigel: I think we should just go ahead and do this now, and deal with any problems later. 16:52:03 .. It's for all TTWG's repos. 16:52:08 .. Any reason not to? 16:52:10 need to drop off 16:53:13 Atsushi: One point - I have opened a PR to add w3c.json on the webvtt.js - it is related to WebVTT. Is this fine? 16:53:30 Nigel: I've never heard of that repo. 16:53:42 Gary: Me neither. I have seen the page it links to, but I did not realise it was a w3c repo. 16:53:51 Nigel: Is it a fork? 16:53:51 -> https://github.com/w3c/webvtt.js webvtt.js 16:53:54 Atsushi: No 16:54:01 https://github.com/w3c/webvtt.js/issues/29 16:54:30 Nigel: I have no view 16:54:36 .. Looks like Dom has been working on this 16:54:56 Nigel: In conclusion, please go ahead with changing master to main. 16:55:02 Atsushi: Sure, it will be tomorrow. 16:55:14 Nigel: Thank you, and you'll let us know when you've done it. 16:55:30 Atsushi: I did a similar thing on Immersive Web CG so no issues should happen, I believe. 16:56:51 Topic: Meeting close 16:57:11 Nigel: The 2021 workplan topic was a placeholder - it seems we have nothing to discuss there, so we've completed our agenda. 16:57:30 .. So let's adjourn. See you in two weeks everyone. [adjourns meeting] 16:57:35 rrsagent, make minutes v2 16:57:35 I have made the request to generate https://www.w3.org/2021/02/04-tt-minutes.html nigel_ 17:13:55 s/sorry for the nuisance, but I don't seem to have any webex coordinates for this meeting// 17:14:03 s/send coords to me alsoo// 17:14:17 s/the "private channel" is not connected to me apparently...// 17:17:33 s/github-bot, end topic//g 17:17:52 s|github: https://github.com/w3c/ttml2/pull/1210|githubX: https://github.com/w3c/ttml2/pull/1210 17:18:10 s|github: https://github.com/w3c/ttml2/pull/1210|| 17:19:30 rrsagent, make minutes v2 17:19:30 I have made the request to generate https://www.w3.org/2021/02/04-tt-minutes.html nigel_ 17:22:19 s/githubX/github 17:22:21 rrsagent, make minutes v2 17:22:21 I have made the request to generate https://www.w3.org/2021/02/04-tt-minutes.html nigel_ 17:23:10 scribeOptions: -final -noEmbedDiagnostics 17:23:16 zakim, end meeting 17:23:16 As of this point the attendees have been Andreas, Atsushi, Glenn, Gary, Nigel, Cyril, Pierre, Mike 17:23:18 RRSAgent, please draft minutes v2 17:23:18 I have made the request to generate https://www.w3.org/2021/02/04-tt-minutes.html Zakim 17:23:21 I am happy to have been of service, nigel_; please remember to excuse RRSAgent. Goodbye 17:23:25 Zakim has left #tt 17:25:51 rrsagent, excuse us 17:25:51 I see no action items