16:02:14 RRSAgent has joined #tt 16:02:14 logging to https://www.w3.org/2021/03/04-tt-irc 16:02:17 RRSAgent, make logs Public 16:02:18 Meeting: Timed Text Working Group Teleconference 16:02:31 Previous meeting: https://www.w3.org/2021/02/04-tt-minutes.html 16:02:39 Agenda: https://github.com/w3c/ttwg/issues/175 16:02:41 scribe: nigel 16:02:50 Present: Gary, Nigel. Pierre 16:02:55 Chair: Gary, Nigel 16:03:42 Present+ Atsushi 16:03:49 Present+ Cyril 16:03:57 Topic: This meeting 16:04:34 Gary: Today we have TTML2, to discuss the updated CR. 16:04:47 .. Then WebVTT, to discuss the current status, talk about outstanding PRs 16:04:55 .. and a new feature request, and what the next steps are. 16:05:07 .. We have GitHub Pages updates and then AOB. 16:05:23 Nigel: You added DST Gary. 16:05:43 .. I would also, if time allows, give an update on the AD profile of TTML2 and implementation state as AOB. 16:06:16 Atsushi: For info share, I need to work on the config updates for some repos. 16:06:29 Nigel: Any other AOB? 16:06:38 s/AOB/other business 16:06:57 Topic: TTML2 - publication of updated CR 16:07:27 Atsushi: I've updated the transition req with the completed document 16:07:51 .. I hope for approval on Friday East Coast US time, and then plan to republish next Tuesday 16:07:54 .. which is the next slot. 16:08:03 .. For now I've run all checks including pubrules and link validator 16:08:09 .. so we're only waiting for approval. 16:08:16 Nigel: Great, thank you. 16:08:30 Atsushi: Sorry for taking time to fix the XSL. 16:08:33 Nigel: Significant changes? 16:08:45 Atsushi: Yes, pubrules have changed for process 2020 so we had to change some headers 16:08:57 .. and some metadata lines, and all of them are handled by the XSL and the DTD. 16:09:11 .. We may need to think about disseminating those changes to TTML1 and TTML3 for the future. 16:09:17 Nigel: Sounds like a good idea! 16:09:29 .. Would be helpful if you could pull request them in. 16:09:38 Atsushi: Yes, you can raise an action item against me. 16:10:32 -> https://github.com/w3c/ttwg/issues/181 Update XSL and DTD for TTML1 and TTML3 w3c/ttwg#181 16:10:42 Nigel: Thank you! 16:10:59 Topic: WebVTT status 16:11:30 Gary: The current status is: last time WebVTT was updated there was a new CR marking some items as at risk. 16:11:53 .. There are more things to mark as at risk, and those items are being built off snapshots of HTML in the repo 16:12:09 .. and are published on /TR, but that output is slightly different than the gh-pages output. 16:12:22 .. I think to make it easier to work on it we probably need to figure out how to bring those two back in line. 16:12:37 .. I don't really know much about the specifics. Maybe for me and Atsushi offline to figure it out. 16:13:08 .. Basically we need to get the changes in that fix the implementation report inline so that we can start progressing the spec forward. 16:13:16 .. However there are a couple of feature requests as well. 16:13:39 .. On the bright side if I understand correctly with P2020 we can republish CRs as often as we want until we want to move to the 16:13:49 .. next step, and then we need to move to the larger CR review. Is that right? 16:14:21 Atsushi: I suppose we need to go through the CR process. 16:14:34 Gary: It sounds like the next update will need to go through the CR process, but updates to that 16:14:41 .. won't need it until we try to go past CR. 16:14:50 Atsushi: I propose to publish as a CR Draft. 16:14:57 Gary: Yes, that's exactly what I was thinking. 16:15:09 Atsushi: Then the CR Draft could be a good pointer for wide review. 16:15:21 Gary: Yes, which I think would be useful because of the feature changes. 16:15:35 Atsushi: Yes, a CRD (not a CRS) can be published by group decision here. 16:15:48 Gary: Perfect, yes. I think probably we'd want to go through several iterations of CRD as we bring 16:15:55 .. in some of these features, until we're ready to proceed. 16:16:19 .. I think that's it for that agenda item. 16:16:28 Topic: WebVTT Outstanding Pull Requests 16:16:47 Gary: I mainly brought them up to remind people they exist, and if anyone has any objection or support, to 16:17:07 .. allow them to voice them. I think they've all been approved, by Silvia. 16:17:25 .. Should I list them here? They're all in the agenda. 16:18:21 -> https://github.com/w3c/webvtt/pull/461 Make VTTRegion lines be a long. 16:18:40 -> https://github.com/w3c/webvtt/pull/470 Update region lines parsing to round to +/- MAX_VALUE 16:18:54 -> https://github.com/w3c/webvtt/pull/460 New snapshot with new at-risk items 16:19:09 -> https://github.com/w3c/webvtt/pull/493 Added unbounded TextTrackCue.endTime 16:19:39 Gary: The end time is the new feature. 16:20:00 .. The items being marked at risk are text-wrap: balance, which I think everyone agrees might be nice but not 16:20:07 .. implementable or verifiable, so just remove it. 16:20:29 .. Then there's text-combine: upright, which might be worth looking at. At the time it was marked at risk because of insufficient 16:20:42 .. browser support, and CSS WG said not to consider vendor prefixes as a good alternative. 16:21:23 .. The snapshot PR adds the new features and adds those at risk items to the existing list. 16:22:17 Nigel: The text-combine: upright - not sure the impact of that? 16:22:36 Gary: Yes, it's not great for Japanese support, and things might have improved, but this may be one where we remove 16:22:52 .. it for the initial release and then add it back in as an "evergreen" feature. 16:23:20 Nigel: I think the term is "candidate feature", i.e. a CR-stage feature that can be marked like that in the Rec. 16:23:39 Gary: Yes, and eventually I think you can do a new snapshot to mark it as a regular feature. 16:23:44 Nigel: Yes, I think there's a process for that. 16:24:30 Topic: [WebVTT] Added unbounded TextTrackCue.endTime w3c/webvtt#493 16:24:39 github: https://github.com/w3c/webvtt/pull/493 16:24:54 Gary: The idea is that a cue can start with a defined time but with an undefined (infinity) end time. 16:25:14 .. The idea is for live streams where a cue, say a chapter, can show up, but then because the end isn't in the live stream yet 16:25:25 .. you want the cue to reflect the end time of the video, which is also infinity for the video. 16:25:42 .. It also aligns it with WebVMT which is a fork of WebVTT which has done that already. 16:25:52 .. I think the change makes sense and is fairly uncontroversial. 16:26:11 Nigel: Is the semantic well defined for updating the end time to a definite value? 16:26:38 Gary: I believe it is, but the fun part is that is defined in HTML! 16:26:47 .. I think it does account for updating the times of the cue. 16:27:05 Nigel: So the change was already made in HTML and we are just tracking it here, is that right? 16:27:16 Gary: There's a pull request out for it, so I guess they want to get it all in at once. 16:27:55 Cyril: Just a remark - do you know that there's a related change request on the carriage of WebVTT in MP4 by Dave Singer, to match this? 16:27:59 Gary: I do not 16:28:04 Cyril: I can tell you there is! 16:28:07 Gary: Makes sense. 16:28:25 Cyril: I see that the HTML pull request is not approved - should we wait for that before we do it in case they make a change? 16:28:45 Gary: Given that the change in WebVTT is 3 words, basically, we can wait to merge it until the WebVTT HTML part is approved. 16:29:11 .. It would be good to make sure all the ducks are in a row on WebVTT, which means figuring out the IPR and checking no-one objects to the change. 16:29:33 Nigel: Unless there is a circular reference it must be clear which one has to move first. 16:29:56 Gary: They sound kind of separate. The HTML one updates Text Track Cue constructor and object to allow the end time to be unbounded. 16:30:32 cyril has joined #tt 16:30:44 .. VTTCue is separate. No, I guess you need both. 16:30:44 rrsagent, pointer 16:30:44 See https://www.w3.org/2021/03/04-tt-irc#T16-30-44-1 16:31:06 Nigel: I can see that the change is to the type of the end time, to be unrestricted double, and defining the interpretation. 16:31:08 Gary: Yes 16:31:31 Cyril: I don't see a change to the serialisation - how would it be shown, as Infinity? 16:31:38 Pierre: JSON can represent infinity 16:31:52 s/can/cannot 16:32:05 Nigel: Right, but this is not JSON 16:32:21 Pierre: Right, but having gone through something similar recently, unbounded/infinity is poorly supported. 16:32:32 .. There's no widely accepted representation - just a data point. 16:33:03 .. For instance as long as you stay within Javascript you can deal with Infinity, assuming the underlying platform supports IEEE floats. 16:33:24 Gary: I think the way WebVMT does it is by omitting the end time after the -> 16:33:37 Cyril: For WebVTT that's a breaking change though. 16:33:58 Gary: Yes, it's possible this is why it is just in the contract for the value, and not in the actual syntax itself. 16:34:18 Cyril: Maybe there should be information about ignoring the end value or having a special value or something? 16:34:37 Gary: Yeah you're right we should figure out whether and how we want to have a syntax for this. 16:35:17 .. Maybe not having the end time, even though it is a change, maybe it can be added on top without breaking things, I'm not sure. 16:36:06 Nigel: Is the requirement only for constructing the VTTCue object in client code, or for providing a serialised fragment of WebVTT? 16:36:31 Gary: Yeah if we only care about the javascript the current change should be enough, and maybe that's a good place to separate it. 16:36:47 .. Do the Javascript contract first and then figure out the syntax. 16:37:25 Nigel: Cyril, does the change you mentioned before about MP4 imply some form of serialisation requirement? 16:37:30 Cyril: I'll have to check. 16:37:47 Gary: Chris Needham's example is Javascript code constructing the cue object. 16:38:20 -> https://github.com/whatwg/html/issues/5297 HTML issue for Add TextTrackCue end time representing end of media 16:38:57 Cyril: The text I can see doesn't talk about serialisation - it talks about what to do if a cue with indefinite duration exists. 16:39:15 .. I don't understand it - it will need review. I don't think it answers your question Nigel, and it raises more. 16:39:46 Nigel: Perhaps it's just explaining how to handle the case, without saying how it might happen, so it's future-proof in that case! 16:41:06 Nigel: Interesting to know how a syntax change would be handled by existing parsers. 16:41:15 Pierre: Have any tests been provided? That might help answer the question. 16:41:28 Gary: The requested change is only to the Javascript contract. 16:41:38 Pierre: So there are no tests?. 16:41:44 s/?// 16:42:06 Gary: No, [checks wpt] there are no tests. 16:42:11 Nigel: Is it testable? 16:42:42 Gary: Yes, it's just create a new VTTCue with an infinite end time and verify that one was created with infinity for end time. 16:43:06 .. For the syntax it is possible that if we add the syntax of no end time the error correction might just ignore that cue. I need to check. 16:44:03 Nigel: Good shout about tests - our working model changed a couple of years ago to try to write tests alongside substantive 16:44:20 .. changes at the time of the PR, so we're not rushing to back-fill the IR at the end when we've forgotten the context. 16:44:25 Gary: Yes 16:45:27 SUMMARY: 1. Make sure we have tests for the change; 2. Enquire whether a syntax change is needed, and if so, investigate if it can be added in a non-breaking way. 16:45:35 Topic: WebVTT next steps 16:45:58 Gary: Some potential steps for moving forward - merge all the outstanding PRs, 16:46:12 .. update the snapshot, go through the CfC process for a new CRS. 16:46:15 Nigel: CRS not CRD? 16:46:32 Gary: I think once everything is in we'd want to go to a CRS before PR. 16:46:43 .. The one thing I'm unsure about is the stuff we want to remove as at risk. 16:46:51 .. Would that be before or after we make the CR. 16:47:18 Nigel: Need to decide whether to remove those features altogether or just mark them as a candidate feature. 16:47:42 Gary: Yeah I think remove text-wrap:balance but mark the text-combine: upright as a candidate feature. 16:47:53 .. That would make it easier than adding it back in later. 16:48:11 Nigel: Would be worth making explicit proposals for each one of these at risk features. 16:48:32 Gary: Yes, I'm describing my view of what I think makes sense to progress WebVTT. 16:48:51 .. Another thing we need to consider is the WebVTT headers - that's another feature I think we should bring in, 16:49:07 .. so that e.g. HLS doesn't need to define its own WebVTT header and can just reference our spec. 16:49:37 Topic: GitHub Pages after switching master to main branch names 16:50:10 Nigel: I noticed a couple of repos using gh-pages were returning 404s on their published URLs, ADPT and IMSC. 16:50:26 .. I haven't checked the others. I managed to kick GitHub Pages into reprocessing them and then they were fine. 16:50:43 Atsushi: 2 things: 16:51:05 .. 1. I found discontinuities in the GitHub Pages API's log. There might be some issue on the GitHub side. 16:51:31 .. 2. I listed 4-5 repos in the agenda+ that refer 404s for GitHub Pages but have a setting. So we need to do a similar operation for them. 16:51:50 .. I somehow doubt that the current configuration for some of these repos is right - that they are pointing to the wrong branch names. 16:52:05 .. Let me check offline with you Nigel for what is the correct config for these repos. 16:52:27 Nigel: Ok - and the difference is whether to publish the main branch or a separate gh-pages branch? 16:52:39 Atsushi: Yes, some are pointing at gh-pages but there's no branch, only a main. 16:52:44 .. I think we need to check one by one. 16:52:59 .. Detailed list is in my email to you - please check. 16:53:08 Nigel: I just had a hard time parsing it! I will have another look. 16:53:17 Atsushi: I have no idea what happened yet. 16:54:18 Nigel: I think there's no point in having a separate gh-pages branch unless there's a build script that makes a separate web page. 16:54:30 .. If it's just respec then we can publish the main branch directly. 16:55:05 Atsushi: I checked the branches and the config, and there were discontinuities. 16:55:20 .. When a change is made GitHub takes the commit and builds something to be provided to the GitHub Pages web server. 16:55:35 s/s./s, from 2017 to Feb 2020. 16:56:17 .. If we use some build script like for TTML, once the CI commits the build result to gh-pages GitHub takes that commit into web server storage. 16:56:22 .. I will check the history of that. 16:57:16 Nigel: All I'm saying is that for respec or markdown documents we can publish main directly. 16:57:28 Atsushi: Yes exactly, I need to check for each repo. 16:57:31 Nigel: Thanks. 16:57:44 Topic: AOB - DST 16:58:11 Gary: DST changes in the US on March 14th, between this meeting and our next scheduled meeting. 16:58:24 Nigel: And it will change in Europe on a later date. 16:58:48 .. Probably Sunday 28th March. 16:59:59 Nigel: Need to confirm offline - I think we will most likely adjust our time to track DST, the only question is when. 17:00:15 Atsushi: I am fine to open a PR to update the calendar files. 17:02:18 Nigel: The only difference between previous DST switches is that we have Atsushi active in Japan. If we adjust to keep local time the same 17:02:30 .. in US and Europe then it will be 1 hour earlier in places like Japan without DST. 17:02:41 .. Will that cause a problem for you Atsushi? 17:02:52 Atsushi: I'm not sure - I will check. 17:03:26 Gary: The EU passed ending DST, but I don't know when that change will happen. The UK is doing something independently. 17:04:03 Nigel: I like to deal with each change as it comes and not worry about it too much in advance! 17:07:03 .. Gary, if you can get round to sending an email today, great, otherwise I will try to get around to it tomorrow. 17:07:13 Topic: Meeting close 17:07:22 Nigel: Thanks everyone! [adjourns meeting] 17:07:26 rrsagent, make minutes v2 17:07:26 I have made the request to generate https://www.w3.org/2021/03/04-tt-minutes.html nigel 17:23:52 s/Nigel. Pierre/Nigel, Pierre 17:23:53 rrsagent, make minutes v2 17:23:53 I have made the request to generate https://www.w3.org/2021/03/04-tt-minutes.html nigel 17:24:21 scribeOptions: -final -noEmbedDiagnostics 17:24:25 zakim, end meeting 17:24:25 As of this point the attendees have been Gary, Nigel., Pierre, Atsushi, Cyril 17:24:27 RRSAgent, please draft minutes v2 17:24:27 I have made the request to generate https://www.w3.org/2021/03/04-tt-minutes.html Zakim 17:24:30 I am happy to have been of service, nigel; please remember to excuse RRSAgent. Goodbye 17:24:34 Zakim has left #tt 17:27:07 rrsagent, excuse us 17:27:07 I see no action items