- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Thu, 12 Nov 2020 17:23:22 +0000
- To: TTWG <public-tt@w3.org>
- Message-ID: <492579AC-D380-4FF8-B6DB-D30A8528C625@bbc.co.uk>
Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2020/11/12-tt-minutes.html In text format: [1]W3C [1] https://www.w3.org/ Timed Text Working Group Teleconference 12 November 2020 [2]Previous meeting. [3]Agenda. [4]IRC log. [2] https://www.w3.org/2020/11/05-tt-minutes.html [3] https://github.com/w3c/ttwg/issues/158 [4] https://www.w3.org/2020/11/12-tt-irc Attendees Present Andreas, Atsushi, Cyril, Gary, Nigel, Pierre Regrets - Chair Gary, Nigel Scribe nigel Contents 1. [5]This Meeting 2. [6]Remove applicability of tts:direction on <p> w3c/ttml2#1214 3. [7]Process 2020 - Living Standards 4. [8]Process 2020 - Patent Policy 2020 5. [9]AOB - text tracks and MSE 6. [10]Meeting close Meeting minutes This Meeting <atsushi> (will come shortly) Nigel: [iterates through agenda] TTML2 - maybe we need to discuss the pull request for 1212 … Do we need to discuss MPEG liaison? Cyril: I don't think you've received it yet, I'm trying to track it down. I don't think we need … it on the agenda, I think I have an action to work with Pierre on the wording, which we … can discuss next time maybe. Nigel: Ok, let's remove that from the agenda. … Next is 2 Process2020 topics, default branch name, and AOB. … Is there any other business? Cyril: There was a Media WG meeting the other day and I raised the idea of text track … support in MSE and there was some good feedback. Nigel: OK, AOB+ that. … One from me: status of TTML Profile Registry publication. Remove applicability of tts:direction on <p> w3c/ttml2#1214 github: [11]https://github.com/w3c/ttml2/pull/1214 [11] https://github.com/w3c/ttml2/pull/1214 Pierre: My summary: long discussion on #1211. Boils down to what does tts:direction … actually do when applied to p. 4 options available: … 1. Keep things exactly as is by having tts:direction on p have no effect on the inline progression direction. … This is probably what TTML and XSL-FO have in mind but is incompatible with CSS3. … 2. Make things consistent with current CSS by having tts:direction on p override the inline … progression direction set by the writing mode. … This is inconsistent with existing TTML and XSL-FO. … 3. Make tts:direction not applicable to p and instead set the paragraph embedding levels differently. … 4. Keep things as is but note that the result of applying tts:direction on p is implementation-dependent. … The PR I propose is a compromise, option 3 here. … It makes tts:direction not applicable on p, removes the opportunity for inconsistency. … Instead the paragraph embedded level is set from the computed value of the … writingMode on region, so it is always set to the inline progression direction as determined on region. … It's consistent with the spirit of TTML, and compatible with modern CSS, and if we ever … change our mind we can make tts:direction applicable again and maybe then it will be … more obvious what to do. … As an aside, we have to decide what to do with unicodeBidi on p, which should be easier … to deal with. Andreas: I have minor comments on the pull request but in general I fully agree with the … intent, for the reasons Pierre mentioned. Nigel: What's the impact in terms of potentially breaking existing documents? Pierre: It's really hard to tell. I've not seen many if any right to left IMSC documents in the wild. … The few I have seen I think just set the writingMode and that's it, without any direction. … I don't know, in terms of hard numbers. … If we're going to settle on something now is a good time. Nigel: Not quite what I meant - rather, if there were a document with direction on p, and … we made this change, what would be the impact? Pierre: If the author set direction to explicitly set the paragraph embedding level explicitly, … presumably that would be consistent with the writingMode, because it would be unusual … to set the two unequal, so there would be no change. … If an author had used tts:direction on p to override the inline progression direction set … by writingMode that would break those documents. Why would someone do that? Maybe … because they think they're in CSS? This approach would break those documents, possibly. Andreas: If you specify tts:direction on p or reference a style through some inheritance then … it is actually specified for p. It is not an error - you can do it even if there is no effect. … The question about the change breaking, my interpretation is that you would set direction … on p and there is a deterministic behaviour expected for the rendering. From the long … long thread we had on that, where all the experts were discussing and could not really … get a grip on it and agree, it seems to be agreed that there's no deterministic behaviour … so therefore it doesn't break anything. On the contrary, if you do that, it might not even … break an existing application. I would argue that if an application would render it the … way CSS3 does it, it would maybe be okay, but at least not an error. … If you now fix and make normative a deterministic behaviour then it is very clear that … some implementation is no longer conformant. Nigel: Thanks, that's a good point, definitely food for thought. … I think what you're saying is that this change removes from reachability some features … of CSS, in that you couldn't get a mapping from a TTML2 document by a processor … conformant to this PR, which would end up setting the direction property on a p element. … If you're mapping from TTML to HTML + CSS, say. … Is that fair? Pierre: exactly. The only place where you would set the direction property would be the … equivalent of the region TTML element, which is fine because that's where the inline … progression direction is set. Cyril: When Pierre said he hadn't seen Arabic documents in the wild I was wondering what … we do at Netflix. We have 100,000s Arabic documents. I picked one completely at random … and it uses direction on p. … I will paste the example. … The document I have has no writingMode on the region at all. <cyril> <p xml:id="p1" begin="00:02:15:02" end="00:02:16:16"><span tts:unicodeBidi="embed" tts:direction="rtl">اجعل نوم أخيك...</span></p> Andreas: The direction is on span not p Cyril: Sorry, I need to wake up! Andreas: Exactly how it should be used. Cyril: I will try to see if we ever use direction on a p Pierre: In general that's the question. Nigel: It seems like Netflix is the best placed to give us real world data. Cyril: I'm looking. I think the difficulty is checking various vendors. I suspect that if all … vendors use the same tool, given there's a restricted set of production tools, once we have … looked at the output of all those tools, if none of them use direction on p then we're … probably in good shape. <cyril> <p style="style.default" region="region.after.center" begin="00:00:12:00" end="00:00:14:07"><span tts:direction="rtl">مسلسلات NETFLIX الأصلية</span></p> Pierre: If they use it on a p and it is consistent with writingMode then it's not terrible. Cyril: Another example above, again nothing on the p or region … I will run some queries before expressing an opinion on the change. Andreas: It's also important to see what would happen if you removed it if you do find it. … It should be an interoperable behaviour, and at least it should be tested. Pierre: I will work on implementing Andreas's suggestions - they don't change really the … fundamental proposal. … I do want to understand why the group concluded that unicodeBidi is not applicable on p … when CSS does say some values are applicable to p. I'm happy either way. It would be … good to get confirmation there. Andreas: I've seen in your comments you asked for a reference. I couldn't find the discussion … part but in one of Glenn's latest comment he said he considered removing the application … of unicodeBidi from p in a later version and that's my recollection from the discussion as … well, and there's issue #1212 that says to do this. Pierre: If you go to the latest CSS drafts, some values of unicode-bidi that do have an impact … on p, including embed. We should point to some discussion or assessment in the PR I think. Andreas: There is a part of the minutes where Elika explained what they do if it is applied to p. Pierre: yes, it's in the CSS spec. I think that's less urgent. … My goal is to close this by end of year. Nigel: Good discussion on this given the PR is only 11 hours old so already a massive step … forward, let's keep reviewing. SUMMARY: Continue reviewing Process 2020 - Living Standards Gary: I wanted to get your thoughts on Living Standards in particular because of how … tied WebVTT is to the web platform, and because of how it seems that living standards, … if you've never been a Rec then it's a bit easier to become a living standard. … It seems like adopting it for WebVTT makes sense, since it allows us to get a minimal … release out and then add features as we go along. Nigel: By living standard do you mean continual CR or a Rec that can be updated. Gary: I imagined Rec that allows us to update, and provides a path for moving ahead with WebVTT. … It allows new features to be added. Nigel: Thanks, any views? Andreas: Just for my understanding, isn't this what Nigel calls a continuously updated CR? … The other way round would be to come to Rec status, but is that what you mean? <atsushi> [12]https://www.w3.org/2020/ Process-20200915/#publishing-crrs [12] https://www.w3.org/2020/Process-20200915/#publishing-crrs Gary: Process2020 does have a new feature for Recs where you say that new features … can be added. Nigel: My reading is that both models exist. <atsushi> [13]https://www.w3.org/2020/ Process-20200915/#rec-track [13] https://www.w3.org/2020/Process-20200915/#rec-track Gary: Atsushi put a link above - there's a section about it Nigel: My understanding is that P2020 allows new features to be added to a Rec but … labelled as being like CR status features, and when they've met the requirements … for Rec the labels can be removed. Atsushi: The group can publish CR snapshots Nigel: I think Gary's proposal is not about CR snapshots? Andreas: Currently WebVTT is still in CR status? Gary: yes Andreas: But you still intend to bring it to Rec? Gary: Yes that would be good for it. Andreas: And then you have the possibility to add features after Rec? Gary: Yes so you can add features individually instead of going through the entire process. Nigel: Imagine turning the clock back for IMSC 1.1 and allowing this to be done to add the … font feature - it would have made things much easier. As long as there's a dated versioned … link that can be referenced externally. Nigel: I think there has to be something in the document itself that says it will use this model? Gary: Yes there's a whole bunch of things that need to be updated and incorporated before … it can be moved on, and the new end time request from Rob that we can discuss another day. <atsushi> might be this one(?): [14]https://www.w3.org/2020/ Process-20200915/#revised-rec-features [14] https://www.w3.org/2020/Process-20200915/#revised-rec-features Nigel: CfC or proposal to make this change and allow people to consider it? Gary: Yes. … Atsushi that link above is the one to start with. Atsushi: Sorry I misunderstood - it's not CRS but a way to add new features to Recs, and … allow the change to be reviewed. Nigel: Yes, it would involve incorporating "Candidate Changes" Atsushi: Yes, 6.2.11.4 and 6.2.11.5 would need to be applied. Nigel: Suggest emailing a list of steps and CfC to allow people to think about it? Gary: Yes sounds good Atsushi: P2020 is already applied, and this is also about revising a Rec after publication. Nigel: I think the document itself needs to explain the working mode. Gary: I believe so, if we want to do it at Rec. Atsushi: First we need to go to Rec, and after that add in new features. Gary: Yes that's the plan, to get the pared down thing to Rec with the addition that says … new features can be amended, and then we can add new features. Nigel: Is your plan to move "at risk" features to Candidate Changes to allow transition to Rec … more easily? Gary: Yes I think so, at least the ones we think should definitely stay in. Nigel: Thanks that would be useful to explain. Gary: One final thing: maybe it makes sense to transitioning IMSC to this working mode. … I know it is more complicated but would be good for any other specs being maintained. Pierre: Gary, I think it's really worth exploring and look forward to seeing how it works for WebVTT! Gary: It should be easier for WebVTT because it isn't at Rec. Pierre: I would like to know what the game plan is for version numbers. Just a year, or a date? … Or a 1st Ed, 2nd Ed, etc. It's worth thinking about how we're going to do this. Gary: Good thought. Pierre: I don't particularly think that the CSS way is very helpful - I find it confusing. Gary: I'm not sure how it's done for the Rec. For the CR model there are dated snapshots. Pierre: That's clear at least. You pick one snapshot and implement it. Gary: That's something I will figure out before sending the email. Pierre: I'm happy to kick around ideas if you want to ping me. That's been a challenge for … IMSC, so maybe there's a better way of doing this going forward. Right now we're discussing … a potential change to TTML2 which is in CR. Do we withhold it, put it in the CR... The way … the world is going how to update the spec is really important. Process 2020 - Patent Policy 2020 Atsushi: We need to ask the question to W3M whether we need to do something. … Two options: … 1. W3C batch update on various WG Charters to update to patent policy 2020, soon. … or 2. postpone application until our next rechartering in 2022. … There will be a WBS on this. Nigel: From a practical perspective I'm not sure the impact on us? Pierre: Isn't there an interaction between the new patent policy and the ability to do CR snapshots etc? … To the extent that we want to consider the new mode of work we might need to switch. Atsushi: For CRD / CRS we would need Patent Policy 2020. Nigel: Nobody is proposing to use that at the moment. <atsushi> [15]https://lists.w3.org/Archives/Member/chairs/ 2020OctDec/0028.html (survey email) [15] https://lists.w3.org/Archives/Member/chairs/2020OctDec/0028.html AOB - text tracks and MSE Cyril: Quick update: the Media WG met and started triaging issues for MSE v2. … Three categories: editorial, in scope and out of scope backlog. … The Media WG encourages people to review the issues in scope, and the out of scope … ones if they care about them. The list doesn't include Text Track support in MSE in scope or … out of scope. I asked the group - they were curious to know what it meant but there was … no immediate position so I take it as a good sign. … I encourage TTWG participants who are also Media WG to create an issue if they are interested. Nigel: Maybe I could talk to you about this offline Cyril? Cyril: Yes Meeting close Nigel: Thanks, we haven't managed to cover Default Branch Name or the AOB on TTML Profile … Registry publication so will postpone those or cover offline. We're out of time for today, … so I'll adjourn. Thanks everyone! [adjourns meeting] Minutes manually created (not a transcript), formatted by [16]scribe.perl version 124 (Wed Oct 28 18:08:33 2020 UTC). [16] https://w3c.github.io/scribe2/scribedoc.html ---------------------------- http://www.bbc.co.uk This e-mail (and any attachments) is confidential and may contain personal views which are not the views of the BBC unless specifically stated. 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Received on Thursday, 12 November 2020 17:23:45 UTC