15:09:07 RRSAgent has joined #tt 15:09:07 logging to https://www.w3.org/2018/11/29-tt-irc 15:09:09 RRSAgent, make logs public 15:09:09 Zakim has joined #tt 15:09:11 Meeting: Timed Text Working Group Teleconference 15:09:12 Date: 29 November 2018 15:11:08 glenn has joined #tt 15:11:35 Log: https://www.w3.org/2018/11/29-tt-irc 15:12:21 Topic: This meeting 15:12:39 Present: Andreas, Cyril, Gary, Glenn, Pierre, Thierry, Nigel 15:12:41 Chair: Nigel 15:12:46 Regrets: none 15:12:59 Nigel: Apologies for the late start today. 15:13:21 .. Our agenda today is at https://github.com/w3c/ttwg/issues/6 15:14:46 .. [iterates through agenda]. Any other business or particular points to raise? 15:15:13 Pierre: It might be too late, but we have this plan for requirements, but have not formally informed other organisations 15:15:29 .. who have cared in the past. I think the announcement was public so we can point people to it but maybe we ought 15:15:47 .. to at least alert SMPTE, EBU. SMPTE meets next week. I wonder if a really quick liaison might be worth it, later today 15:16:01 .. or tomorrow, saying we're gathering requirements, see this email for detail. For discussion if there's time. 15:16:06 Nigel: Thanks, that's a really good point. 15:16:16 .. Anything else for the agenda? 15:16:19 group: [silence] 15:16:30 Topic: TTML Profile Registry Actions, Pull Requests and Issues 15:17:03 Nigel: I don't think there's anything to discuss here, I did give Glenn the prod he requested. 15:17:18 Glenn: I just got back from travelling and am catching up, I'm afraid I'm behind on this but will push on this next week. 15:17:23 Nigel: Okay. 15:18:00 Topic: TTWG Future requirements 15:18:09 Nigel: Pierre's comment above relates to this agenda item. 15:18:30 .. I'm happy to draft something lightweight and send it out tomorrow, it's a good point. 15:19:01 .. Organisations who should receive it are, off the top of my head, SMPTE, EBU. DVB, ATSC, HbbTV, ARIB. Any others? 15:19:10 .. I will also check the liaisons page. 15:19:38 q+ 15:20:03 ack at 15:20:23 Andreas: I just wanted to comment that my colleague Peter tho Pesch recently added two issues in the requirements 15:20:43 .. repository of the XR Community Group on subtitles, especially on requirements for 360ยบ videos. 15:21:02 .. He will send the link to the issues. This is a good place to discuss what could also be covered in a future version TTML. 15:21:19 q+ 15:21:26 Nigel: Thanks that sounds good, if you could ask Peter to raise at least one issue on tt-reqs so we can track that please? 15:21:30 ack glenn 15:22:00 Glenn: I'm wondering if it's worth discussing what are ground rules are for, say, TTML2 2nd Ed vs a new version of TTML, 15:22:18 .. e.g. TTML3 in particular whether or not we are considering new features in TTML2 2nd Ed or if we are considering 15:22:36 .. those only for TTML3. In other words is TTML2 2nd Ed just bug fixes or are we going to try to slot new features there. 15:22:47 .. We haven't discussed this yet. I don't know if we need to discuss it right now. 15:23:07 Nigel: A quick response on that: first let's gather the requirements and then work out how we're going to deliver them. 15:23:17 .. I think this is one of the agenda topics for our face to face meeting. 15:23:31 .. We said we wouldn't work this out immediately. 15:23:36 Glenn: I'm comfortable with that. 15:23:51 .. The only reason I mention it is because as I try to incorporate requirements into the draft requirements document I 15:24:07 .. need to frame them somehow. I can delay doing that for the time being. 15:24:09 Nigel: Sounds good. 15:24:31 Topic: Add generic CSS property functionality tt-reqs#2 15:24:48 Nigel: (I haven't updated github-bot with the tt-reqs repo yet) 15:25:21 .. The discussion here is about if we should only add specific known CSS properties into TTML or one of its profiles or 15:25:47 .. if we should do as the issue requests which is to allow for generic CSS properties to be specified in document instances. 15:26:43 .. The point here is that there's a class of use cases where waiting for new CSS properties to be added to the spec on an 15:26:50 .. annual cycle isn't feasible. 15:27:08 Pierre: That's a good point. I think in this case the way to do it is to create attributes in foreign namespaces so folks 15:27:15 .. can experiment to their hearts' content. 15:27:16 q+ 15:27:41 q+ 15:27:43 .. A new feature is going to require a change to implementations regardless. Using existing CSS vocabulary does not make 15:27:47 .. things easier. 15:28:08 .. I'm trying to think of a scenario where importing CSS would be easier than dealing with specific new attributes. 15:28:39 Nigel: The idea is for a class of processor that simply passes the CSS properties to a CSS based implementation without 15:28:57 .. having to process them any further, and also to put this processor functionality behind a feature designator. 15:29:14 .. I don't think it is especially helpful for standard subtitle and caption presentation for example where the use case is 15:29:18 .. much more tied down. 15:29:23 ack glenn 15:29:44 Glenn: A couple of comments. One is that supporting this feature entails having a CSS processor and integrating that 15:29:59 .. into whatever implementation we're talking about. This would have for example a fairly big impact on TTPE and TTV 15:30:04 .. for example. 15:30:22 .. The other is that in order to make use of any CSS features from a standardisation perspective we would end up having 15:30:50 .. to document each CSS style property that would be used in this feature that describes how it fits into the TTML 15:31:09 .. rendering model. We have based everything conceptually on the XSL model but it has semantics that have in some ways 15:31:26 .. stayed close to CSS. I can certainly see how this might work for edge scenarios for example the one Nigel brought up 15:31:44 .. in his proposal, like specifying a left and right border independently of all borders, for example. But let's say you want 15:32:01 .. to support flex display mode via this mechanism. Now all of a sudden you need to figure out how flex semantics 15:32:20 .. fit into TTML formatting. It may work better in some cases than others and will potentially have interop problems. 15:32:30 .. Those are just the concerns that come to the top of my thinking right now. 15:32:31 ack atai 15:32:49 Andreas: I actually like Nigel's proposal, actually everything that brings us closer to the evolution of CSS and gives us 15:33:04 .. a more direct way of using this process in our standardisation work. I agree we maybe need to play through a concrete 15:33:19 .. example and see how it works but in general I think it's a worthwhile proposal to check. 15:33:36 q+ 15:33:39 .. I think that we agreed, at least the majority of the group agreed, to have a closer mapping to CSS in the future. 15:33:56 .. Nobody knows how it could be done because as Glenn says TTML is not built on CSS but on XSL-FO. It's a step in the 15:34:05 .. right direction. After a concrete example we should reconsider it. 15:34:08 ack glenn 15:34:12 Glenn: 2 more things. 15:34:26 .. The syntactic proposal that is on the table, or something like it, I think would be quite straightforward to support. 15:34:41 .. The semantic one is the more problematic one. Another point I didn't mention before is that such a mechanism would 15:35:01 .. have to entertain the possibility of users using this mechanism to specify properties that are already defined in TTML 15:35:29 .. but slightly differently, lineHeight etc. Now you have a problem what to do. There's a lot of detail to deal with to 15:35:43 .. effectively do this. 15:35:50 Nigel: The order of precedence point is already in the issue. 15:39:08 i/Log/scribe: nigel 15:39:38 Pierre: If only the BBC wants to do this in their own code this doesn't need to be in the standard. 15:39:49 .. There's already an extension mechanism. 15:40:08 Nigel: That's true, my preference is to standardise but you're right if the BBC is the only organisation with a use case here 15:40:12 .. we can do our own thing. 15:40:59 Glenn: I think it's useful to continue on this to the extent that we potentially scope out and spec out a syntactic mechanism. 15:41:19 .. In the end, if the WG doesn't decide to include it in some v.next then if we've defined a reasonable syntactic mechanism 15:41:34 .. then BBC could in fact employ that in their own namespace. Whatever is done here I would insist on it being in a 15:41:51 .. qualified namespace not an unqualified attribute for example. Adding a bare class attribute would be something I would 15:42:03 .. oppose. I would want to see this being in some namespace qualified attribute space. 15:42:28 Pierre: One additional point in response to Andreas. If the long term goal is alignment with CSS then I'd rather spend 15:42:46 .. effort pursuing that. Maybe the long term goal should be for TTML to use CSS period. If that's the goal let's just go 15:42:47 .. there. 15:42:51 q+ 15:43:06 Glenn: We do have a precedent in W3C for something similar to this, in SVG. It has a set of XML defined properties just 15:43:21 .. like TTML that do not depend on CSS. Then many implementations added support for CSS stylesheets on top of SVG. 15:43:39 .. Most implementations support user specified stylesheets. That's a deployed existence proof for doing something like 15:43:55 .. this. I don't know what transitioning to pure CSS means. We made a design decision in the beginning of this group to 15:44:14 .. use XML syntax and not CSS syntax. Short of going back on that underpinning principle we still have an XML syntax 15:44:30 .. for style properties and I don't know how we could move away from that without a non-backward-compatible revision 15:44:45 .. of the current syntax. I fear that if we dive into that discussion it is going to derail the immediate goal of what BBC is 15:44:48 .. proposing here as well. 15:45:05 Pierre: Glenn, my point is that BBC's proposal here has implications on semantics that will force us to solve the bigger 15:45:24 .. issue. There is no perfect 1:1 mapping here. It's close, but applying CSS semantics to TTML is going to be 15:45:31 .. straightforward in some cases and not at all in others. 15:45:33 Glenn: I agree. 15:45:54 Pierre: This will force us to solve the deeper issue, of using CSS period. 15:45:56 ack at 15:46:11 Andreas: In general I agree with Pierre I think. Possibly the BBC proposal is a good opportunity to discuss this question 15:46:25 .. and elaborate how we can use CSS more directly in TTML. Glenn is right that over 10 years ago there was a decision 15:46:40 .. to use XML and base styling on XSL-FO but the situation has changed a lot since then so we need to face the new 15:46:47 .. situation and find an answer for a future-proof model. 15:47:03 Nigel: Thanks everyone for the great discussion, shall we move on from this topic? 15:47:20 Glenn: One last comment. I haven't looked at what SVG did to accommodate CSS usage but it's a really important 15:47:43 .. precedent given that it mixes XML styling with CSS, which mirrors TTML in terms of the overlap between properties. 15:48:00 .. Perhaps Nigel or somebody promoting this can take a look at SVG to see if there's any guidance there. 15:48:03 Nigel: Good point, thank you. 15:48:35 q+ 15:48:38 Topic: f2f meeting and Joint f2f meeting with EBU Timed Text, Feb 1 2019 15:48:41 ack g 15:48:57 Glenn: A quick comment on requirements in general, I had written in the guidelines about the requirements that 15:49:18 .. people are encouraged to create a marked up document with more guidance on the issue. I'd ask people raising 15:49:23 .. requirements to try to undertake that. 15:49:38 Nigel: Noted, I did intend to do that. 15:49:50 q+ 15:49:53 Nigel: On the topic of the meeting, the dates and location are all confirmed. 15:49:56 ack a 15:50:18 Andreas: We discussed this week the joint f2f meeting and had the idea to kick off the joint meeting with some 15:50:37 .. short presentations, on implementation work, the EBU-TT Live Toolkit, some requirements from broadcasters about 15:50:54 .. contribution of live subtitles to web streams. BBC, Red Bee Media and IRT are interested in giving short presentations. 15:51:12 .. Is this okay with the TTWG members? If yes then we can allocate time later. I think it should not be too long, maybe 15:51:17 .. half an hour maximum. 15:51:34 Nigel: Any objections to doing that? Any requests or proposals for additional presentations? 15:51:55 Andreas: I think it would be interesting to hear if there are requirements from outside Europe that are not covered, for 15:52:07 .. example from north America. That could be interesting if there is anyone to present it. 15:52:26 Glenn: I know I've mentioned it a couple of times in the past. One thing people have kicked around in the past is some 15:52:44 .. support for karaoke. That's a possibility. I'm not volunteering but will try to reach out to those folk. 15:53:01 .. We haven't logged an issue yet that records a requirement in this area. I haven't received any concrete proposal yet 15:53:06 .. but it is possible that one will appear before then. 15:53:33 Nigel: I'm hearing no objections or proposals for other presentations so right now I believe we have consensus to go 15:53:38 .. ahead with that idea Andreas. 15:54:30 -> https://www.w3.org/wiki/TimedText/F2F-jan-2019 F2F wiki page 15:55:04 Nigel: Thanks for raising that Andreas, if you want to go into the wiki page and add those in, that would be great. 15:55:31 Andreas: Yes, I will check back with the presenters and then add them. 15:55:33 Nigel: Thank you! 15:55:46 Topic: CSS Actions Review 15:56:02 Nigel: I just want to say something quickly about this. Yesterday there was a special CSS WG meeting to discuss 15:56:31 .. line sizing, whose minutes should be out soon if not already. In particular I raised the question about whether ruby 15:56:45 .. reserve is included in the line height calculation or not, and if so, how. 15:57:18 .. This got raised as an issue, and the initial view was that any ruby reserve space should be added to the leading 15:57:23 https://lists.w3.org/Archives/Public/www-style/2018Nov/0032.html 15:57:25 .. to achieve the necessary effect. 15:57:45 .. So folk interested in line sizing and ruby reserve might want to go and take a look at that. 15:58:30 .. The issue of background area painting did not arise because it's orthogonal given that there's already a draft property 15:58:40 .. for setting the background height to extend to the line edges. 15:58:47 Glenn: What is that property, for the minutes? 15:59:26 -> https://www.w3.org/TR/css-inline-3/#line-fill CSS line-fill property 15:59:50 Nigel: The "stretch" value extends the background to the line box edges. 16:00:14 Topic: WebVTT 16:00:22 Nigel: We don't have David on the call, but let's do what we can. 16:00:40 .. The first thing to do (which everyone else did before I came late to the call) is to welcome Gary who is the new Editor 16:00:43 .. of the WebVTT spec. 16:01:12 Gary: There hasn't been much activity but I heard that there needs to be work done to move the spec forward for 16:01:28 .. Candidate Recommendation. I'm pretty new to this whole thing. If there wasn't anyone working on it the WG would 16:01:46 .. recharter without WebVTT but theoretically it could be re-added the following year. For me the most important thing 16:01:58 .. to work on is an implementation report and get it done as soon as possible. 16:02:21 Thierry: As you mentioned the spec is currently in CR so the next goal is to exit CR and move to Proposed Recommendation. 16:02:34 .. You're probably aware of the exit criteria in the CR SoTD section. 16:02:53 .. We need two tests per feature so we usually demonstrate that through an implementation report. I saw in your 16:03:12 .. slide that Silvia sent the URL for that the report you have is very similar to an implementation report. It would be 16:03:24 .. good enough but from what I've seen it is just a subset of the features. 16:03:41 .. Therefore what the group would be looking for is a full implementation report running the test suite against the 16:03:58 .. four browsers. That would certainly help and having the current status of the implementation experience. 16:04:14 .. Also Silvia mentioned non-browsers and I would like to understand if there are other products to use, such as VLC, 16:04:20 .. set top boxes or polyfills. 16:04:38 Gary: I think VLC is probably the biggest one. JB told me at FOMS he had implemented the spec fully. We would want 16:04:54 .. to ratify that. If we can use VLC then that's one implementation. Safari tech preview has most of the spec complete 16:05:04 .. as well and they seem to be onboard with updating things if there are any bugs. 16:05:22 .. Also dash.js and shaka and the vtt.js polyfill implement it and we can update the polyfill as necessary. 16:05:30 Thierry: So the tests can be run on VLC? 16:05:37 Gary: Probably they would need to be run manually. 16:05:54 Thierry: OK. Just to clarify, we are not looking for a product that implements the full spec. You could have one that does 16:06:13 .. half, another three fourths. We are looking for each feature to have two implementations. A full implementation 16:06:21 .. is great but not mandatory, to clarify. 16:06:33 .. Would you be able to provide such a report, running the tests on the players? 16:06:51 Gary: Yes, the slides were just the web platform test results. The rendering tests require manual review but the 16:06:58 .. parsing and API test results are complete. 16:07:05 .. I can go through that and collate a report. 16:07:20 Thierry: That would be great and would definitely help us to know the status of WebVTT against implementation experience. 16:07:30 .. If we are close to our goal of the exit criteria that would be good news. 16:08:42 .. Just to explain David has not much time so we are kind of missing a Chair for WebVTT but I am ready to help. First 16:09:00 .. let's start with this implementation report and understand more deeply and schedule your attendance to calls as needed. 16:09:13 .. You can attend all the calls, it's not a problem, but we're not going to talk about WebVTT every week I guess. We can 16:09:23 .. schedule calls with parts dedicated to WebVTT. 16:09:25 Nigel: +1 16:09:44 Pierre: Gary, thank you for joining today, it's great to see progress there. I think we really need a Chair somehow. Gary 16:10:06 .. that could be you. Don't quote me on it but it should not be much work. I think we really need a Chair for this effort. 16:10:11 .. Thierry I don't know how you want to do this. 16:10:30 Thierry: W3 Staff are not allowed to be Chairs. If Gary wants to do that I can request that of course. 16:10:52 Gary: I would be willing to do that. As Pierre said I don't think it's much extra work except for transition but I will help 16:11:03 .. you do that as I do with Nigel. 16:11:16 s/As Pierre/Thierry: As Pierre 16:11:24 tmichel has joined #tt 16:12:18 Nigel: I'd be happy to schedule a call Gary with you and Thierry if you want to discuss Chairing more. 16:12:22 Gary: That's a good idea. 16:12:59 Thierry: Just one more issue is: Gary are you aware of more comments that came in that we need to address with tweaks 16:13:05 .. in the spec? 16:13:18 .. For example anything substantive that would need a new CR? 16:13:34 Gary: I am not sure if there's anything new. There might be something that is currently an issue against WebVTT but 16:13:45 .. I'm not positive if changes are needed or not. I can talk with Silvia and find out. 16:14:04 Thierry: Okay. The last thing is if we don't fulfil the exit criteria, let's say there are 2-3 features not implemented, they 16:14:25 .. can be marked as at risk in a CR edition and removed to allow us to get to PR. The Rec would then miss those features. 16:14:36 .. Those are also possibilities if we don't meet 100% of features implemented. 16:14:41 Gary: That's good to know. 16:14:51 Topic: AD Community Group 16:15:26 Thierry: I know that Nigel is working Chairing the AD CG. I saw recently that it was put into the Strategy Funnel and 16:15:47 .. therefore I'd like to understand more about how you see this work entering the TTWG? 16:15:56 .. Would you like it in the next Charter? 16:16:25 Nigel: I think I've made this point before - there's issue #4 on tt-reqs for example. 16:16:47 .. The current status is there's a very rough draft spec for the AD profile and there's one implementation that I'm aware 16:16:53 .. of so far, which is the BBC's. 16:17:07 .. The AD CG has I think 19 members currently, one more joined today or yesterday. 16:17:33 .. My goal is to get to a point of "good enough" spec material to bring it into TTWG in the May 2019 Charter. Since it is 16:17:47 .. a relatively small profile of TTML2, I am hoping we can get to Rec very quickly. 16:18:21 .. It's challenging but feasible I think to have the ADPT profile at Rec by this time next year. 16:18:31 .. Does that help? 16:18:35 Thierry: It sure does! 16:18:51 .. Are there a lot of people in the AD CG who are not yet participants of the TTWG? If that is the case would you think 16:19:00 .. that some people would join in the TTWG and bring in new blood? 16:19:23 Nigel: Yes, possibly. I would hope so, if only because from the current active membership of TTWG I don't think there has 16:19:49 .. been a lot of input. The one exception is the Editor is currently John Birch who certainly was and may still be an 16:19:55 .. Invited Expert member of TTWG. 16:20:42 Thierry: That triggers a last question: how do you envision the way this spec will be specified? 16:20:59 .. Would you like to work like we currently do with the Media Track CG which does all the specification and editing and 16:21:10 .. then bring it to the TTWG or would you like the CG to join the TTWG and work within it? 16:21:31 Nigel: I would be open to different models but my preference is there is one clear home for this spec work and when we 16:21:54 .. move into TTWG then TTWG is that home. It would still be encouraged that AD CG members provide review feedback 16:22:08 .. and of course they can provide implementations too - there's nothing that says implementations need to be provided 16:22:16 .. only by WG members. 16:22:40 Thierry: That's a good point that it needs to be clear where it's defined. I think it is better to have it in the TTWG if 16:22:54 .. the current participants are okay with that and if there are new participants who come in and help that would be great. 16:23:27 Topic: Meeting close 16:23:45 Nigel: Thank you everyone for a productive meeting as always, and apologies again for the late start. [adjourns meeting] 16:24:12 rrsagent, make minutes 16:24:12 I have made the request to generate https://www.w3.org/2018/11/29-tt-minutes.html nigel 16:30:09 s/Thierry: As Pierre said I don't think it's much extra work except for transition but I will help// 16:30:45 i/.. you do that as I do with Nigel./Thierry: As Pierre said I don't think it's much extra work except for transition but I will help 16:30:48 rrsagent, make minutes 16:30:48 I have made the request to generate https://www.w3.org/2018/11/29-tt-minutes.html nigel 16:31:31 s/.. you do that as I do with Nigel./Thierry: you do that as I do with Nigel. 16:31:33 rrsagent, make minutes 16:31:33 I have made the request to generate https://www.w3.org/2018/11/29-tt-minutes.html nigel 16:32:45 scribeOptions: -final -noEmbedDiagnostics 16:32:46 rrsagent, make minutes 16:32:46 I have made the request to generate https://www.w3.org/2018/11/29-tt-minutes.html nigel 17:53:04 Zakim has left #tt