- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Thu, 23 Mar 2017 16:15:38 +0000
- To: Timed Text Working Group <public-tt@w3.org>
- CC: r12a <ishida@w3.org>
- Message-ID: <D4F9A4D1.3B315%nigel.megitt@bbc.co.uk>
Thanks all for attending today's TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2017/03/23-tt-minutes.html In text format: [1]W3C [1] http://www.w3.org/ Timed Text Working Group Teleconference 23 Mar 2017 See also: [2]IRC log [2] http://www.w3.org/2017/03/23-tt-irc Attendees Present Nigel, dae, Pierre, Thierry, Glenn, r12a, Andreas Regrets Mike Chair Nigel Scribe nigel Contents * [3]Topics 1. [4]This meeting 2. [5]TTML 3. [6]IMSC * [7]Summary of Action Items * [8]Summary of Resolutions __________________________________________________________ <scribe> scribe: nigel This meeting nigel: For today we have some TTML issues and hopefully we will have r12a joining us ... shortly. For IMSC I think we need to record publication of the WR and think briefly ... about the next steps. I will leave that until later in the meeting. Any other business, or ... constraints? Thierry: Someone from VideoLan sent me a few messages yesterday, and he said that the ... IMSC spec has a lot of issues, not only considering the two additional features, but also ... the Rec. He said that the test suite is not good enough, so I have asked him to raise ... those questions to the mailing list. ... So he should send something. Pierre: Jean-Baptiste? Thierry: Yes Pierre: In the context of imscjs I've created a more thorough test suite based on the TTML ... test suite (with bug fixes and made compliant with IMSC1) and the IRT test suite, and I ... have slowly been adding additional tests as people bring up additional test cases. The ... suite consists of the TTML documents and some intermediate documents and output ... images. I can point to that, and my goal is to submit that back to W3C as a complete ... IMSC test suite. Just time has been stopping me from doing that. There are a couple of ... bugs and some tests to add and then it should be good. ... Please let me know if there are any obstacles to doing that. Thierry: It is probably not clear that the goal of the W3C test suite is for interop not for <pal> [9]https://github.com/sandflow/imscJS/tree/master/src/test/reso urces/reference-files [9] https://github.com/sandflow/imscJS/tree/master/src/test/resources/reference-files Thierry: product testing. I'm not sure how we explain that, but maybe I could look at it and ... add some words to explain that. It is good for our purposes not for implementors. nigel: However a test suite that is good for implementors will suffice for our purposes too? Thierry: yes. Nigel: Just closing off on this meeting, any other points to raise? group: [silence] Nigel: Just a reminder, in 2 weeks on 6th April I will be unable to join the meeting so if ... anyone wants to step in to Chair, please let me know. TTML <r12a> [10]https://github.com/w3c/ttml2/issues/277 [10] https://github.com/w3c/ttml2/issues/277 r12a: If we had agreement on this then it might make things easier to discuss in other areas. Dae: Link to the CSS document please? <r12a> [11]https://drafts.csswg.org/css-writing-modes-3/#block-flow [11] https://drafts.csswg.org/css-writing-modes-3/#block-flow r12a: The reason I raised the issue in the first place is because TTML says it is following ... CSS but CSS has recently changed before going to CR. The change was that instead of ... using the vertical-lr and vertical-rl and then fiddling with text-orientation to make ... latin text run up the page for example there are two new values for writing-mode, which ... are sideways-rl and sideways-lr and they are specifically for horizontal text in a vertical ... arrangement, e.g. for text running alongside a table these would be useful. If you had ... some latin text running up the page and you text-align it to the end of the line, in the ... old way the text would drop to the bottom, but with sideways-lr the text rises to the top ... as you would expect. It also makes it easier for line breaking and the default orientation ... for characters is much easier to handle. This makes things much easier. ... This leaves text-orientation only applicable to vertical-* writing modes, which are what ... you would use for Chinese, Japanese and Mongolian most of the time. They determine ... the default orientation of characters according to Unicode TR. ... So the text-orientation property becomes a way of influencing what's happening in ... those vertical- modes, so for text to stand upright you would apply text-orientation. ... But normally you would use the sideways- values. Glenn: Right now the writingMode property in TTML is based on the XSL-FO spec rather ... than CSS. Nigel: Doesn't it fall through to CSS? Glenn: No, and certainly not to the current version. Actually it enumerates all the values. ... At the time there was no writing mode in CSS. ... Also, since this is based on TTML1 we don't have a lot of room for changes there because ... it is already deployed in the field. The second point is that textOrientation right now ... has a default of "mixed" so horizontal scripts would be in sideways mode. So right now ... if you use tbrl or tblr with Latin text it would put it in sideways mode so you would end ... up getting what is apparently (I haven't read the details of the new CSS specs) the same ... as the sideways mode, and you don't have to specify that since it is the default. ... So I think it works exactly like you sais. ... Also the textAlign default is start which would mean that if it were bidi Arabic it would ... put it at the bottom in a vertical mode. ... Again it would work correctly for both lr and rl paragraphs and would derive the textAlign ... from that so Latin script in vertical lr would be aligned at the top, and Arabic at the bottom, ... so it would get the same result. So I don't see any particular advantage in pulling in those ... values from CSS at this point given the functional similarities. r12a: I suspected there would be some legacy here so I put in the issue that perhaps one ... issue would be to keep the legacy and if you want to introduce the new sideways modes. Dae: One question about the CSS document. It says the sideways values link to level 4 but ... all those links are broken. r12a: I thought it said they are at risk. Dae: The newer editor's version seems to defer them. I'm not sure which version is newer. ... A general to the question: how do we deal with values that are at risk or being deferred. Glenn: textOrientation is a new property in TTML2 but writingMode was there previously ... so we have to work around that a bit. The current definition is that the default initial ... value is "mixed" which is defined as [reads definition from TTML2]. [12]https://w3c.github.io/ttml2/spec/ttml2.html#style-attribute -textOrientation [12] https://w3c.github.io/ttml2/spec/ttml2.html#style-attribute-textOrientation Glenn: So you don't need to use sideways because you get the same default behaviour. ... The only time you would need to use sideways is... hmm, that raises in my mind the question. ... I guess if you had set the default to upright and you wanted to override with sideways ... you might do that explicitly. r12a: The mixed default is perfect. It says "glyphs ... are set 90º clockwise" which is fine, ... but then it does not clarify in my mind whether if the word "Hello" would have H above ... or below e - it sounds like only the glyphs are changed so you might end up with olleH ... in the text. That was a stumbling issue in CSS and why they moved to the new model. ... The other thing is "Hello world" in English and sideways-left is applied and then ... textAlign is applied then there is the question of which way does the text move if it is ... smaller than the box? That's not a glyph thing, it's a box thing if you like. Not just a ... question of turning the glyphs around but applying a different mechanism to the way ... the box is working. Glenn: I think you're talking about the baseline and referring to the fact that in vertical ... scripts you will sit on a centre baseline whereas a roman script will have a non-centred ... Latin baseline? r12a: No I'm referring to the distinction between twiddling the orientation of the glyphs and ... changing the line direction. The TTML2 spec only seems to talk about changing the glyphs ... individually not the group of glyphs. Glenn: So if you had sideways-left then you would expect Hello to have H on the bottom and ... ascenders pointing right? r12a: The worry is that might not be the case, and that might not be the case in CSS. ... You might still read H e l l o down the page and the descenders would point to the left ... instead of the right, in sideways left mode. Glenn: I guess I did not say "clockwise" or "anticlockwise" relative to what. I meant relative ... to an upright position. That would mean counterclockwise 90º would put the ascender ... to the left. r12a: Right. Glenn: In both cases I don't see anything about if it affects the entire line box as well. In ... other words model as though setting horizontal text and rotate the line instead of the ... glyphs. OK that's a fair point. r12a: When the CSS folk realised that they switched to new values for writing-mode instead, ... because that affects alignment, position of characters in the line box, etc. so it turned ... out to be a convenient way of looking at the world. Specifically for use with what are ... normally horizontal scripts - there are plenty of situations where you want them to run ... up or down the page rather than horizontally. Glenn: That's fair. In TTML1 we had an example of a latin script in a vertical mode and we ... used upright glyphs in the example which raises the point of if it is valid to change to ... mixed for TTML2 and have "mixed" cause rotation, which would invalidate that example, ... even though the example was informative. That could be an issue we should document ... and talk about more. ... I understand the comments now, Richard, thanks for those. I want to give it some ... more consideration, but I think you also understand some of what TTML2 has done at this ... point. There are also some existing implementations of the new features that have been ... deployed so we have to be a little sensitive about those too. r12a: One more thing: these sideways values in CSS are best thought of as a way to ... rotate the box rather than the character glyphs. It helps with understanding what is ... going on. ... That's not necessarily what happens, but it's helpful for thinking about it. Glenn: There may be some value in that to do with the issue of whether you start at the ... top or the bottom. I need to cognate on that a bit more. The rotation of glyphs though ... is still a relevant point because fonts have rotated variants and in the case that a font ... does not have rotated variants it may perform the rotation manually on a glyph by glyph ... basis. This comes up in asian scripts more than in roman scripts. But the same rotation ... dimension applies to any font. r12a: CSS does still have a sideways value for text-orientation for that kind of scenario. Glenn: I had a conversation with @fantasai about this a few years ago, after which I think ... the sideways versions of text orientation were taken out. We had to rely on the state ... of the CSS definitions at that time. Dae: Do we know when Level 4 is coming out? Are we confident that the definition of ... sideways won't change? r12a: I don't know the a-z of that - I know she read this and agreed with what I was ... recommending. Firefox has implemented sideways-* already, so I am hoping that we ... would get Chrome to support those also, so I will follow up on the status of that. Glenn: Dae I think we cannot make any schedule dependent on a CSS document appearing ... at Rec, so keep that in mind. Pierre: Flipping the question around: can the CSS document reach Rec? And by what time? r12a: I know they have been talking this week about fast-tracking some specs including ... Writing Modes so I am hoping it will reach Rec. Pierre: It is hard for this group to follow a CSS spec without a clear schedule, because the ... risk is high. r12a: That is something to talk to CSS about - it would help them I think. ... Like Glenn said, it would be great for users as well if CSS and TTML work in similar ways ... because they would not need two ways to think about things. There is the possibility ... of moving ahead with this if they make sense. There are lots of examples of that in ... TTML2 for example with Ruby, alignment and so on. Glenn: I have brought some of those up in the past with Elika and Koji. Nigel: Let's move on to the next issue then: [13]https://github.com/w3c/ttml2/issues/240 [13] https://github.com/w3c/ttml2/issues/240 Nigel: Pierre I think last week you thought we may be able to conclude on this? Pierre: My conclusion from the thread is that there is a mapping for every option in CSS ... to every option in TTML and the discussion is about the best default. r12a: That's my understanding as well. There are three things that have been coming into ... the conversation. They are to do with things that sit alongside the vertical line. ... One things is text emphasis marks, another is Ruby, and another is "lines". Actually ... the position of those things may be different depending on which thing they are. ... There is a Ruby issue for #240 but that might not be appropriate until we've decided ... what to do with textEmphasis. Then for me the question is what is the default specifically ... for tblr - I'm not worried about tbrl. Pierre: The default in TTML2 for some writing mode might not be or might be what ... someone expects depending on language. The challenge is changing the value of ... the default based on the value of something else makes the processing algorithms very ... complex. That would be an implementation burden. If the issue is simply one of defaults ... we might have to accept what TTML is today. Glenn: I concur with Pierre. We need to have a default for each property, that's a given. ... There's no argument about whether "before" should be the effective default for tbrl or ... any of the horizontal modes. The only question is if it would be appropriate if you were ... using Mongolian, which apparently puts text emphasis on the after edge for tblr writing mode. ... Now Mongolian can also be written in tbrl where you would want it to be on the before ... side (the right side). r12a: That's not true - you never write Mongolian tbrl. Glenn: I have seen a number of manuscripts at Harvard that were directly from the imperial ... language in Beijing and those were all in tbrl. r12a: Were they Chinese documents? In that case you would see tbrl. Glenn: They were pure Mongolian with occasional Chinese characters in. They were created ... using the same writing practice as normal in Chinese with a scroll that gets unwound to ... the left and the right roll gets wound in. In Mongolian they shift the scrolls 90º counter-clockwise ... so in those scrolls they look tbrl in pure Mongolian. I've never seen a tblr Mongolian ... document in my own research but I haven't looked at modern Mongolian other than what ... I have seen in Chinese word processors in Inner Mongolia. I don't recall looking at text <r12a> [14]https://github.com/w3c/type-samples/issues/55 [14] https://github.com/w3c/type-samples/issues/55 Glenn: emphasis in those contexts though. ... For me it's like Pierre said, adding a variation in how to derive the default behaviour ... based on potentially a resolution of xml:lang would certainly complicate things and ... from an implementation perspective it would be much easier to apply "before" to all modes ... and then if one wants to do something different use the initial element in TTML. ... There's no argument about what Richard says. r12a: I just put a link into IRC by the way with some Mongolian text. I have been working ... with Mongolian experts over the last 2 years and seen a lot of Mongolian text. This example ... was sent to me a few days ago, with "underlining" that appears on the right hand side. ... All of the text I have seen goes tblr. Let me clarify that I'm not asking for a decision to ... be made based on the language. I am asking for the default to be dependent on whether ... we have tblr or tbrl as the value, which is what CSS does. Also to clarify that the requirements ... for Mongolian as I understand them from talking to Mongolian folks is that the same side ... is used for the emphasis as Japanese, which means that for horizontal the line appears ... on the other side, the same as Japanese, on the right for vertical or underneath for ... horizontal. CSS has the same default for Mongolian as for Japanese for underlining. ... For text emphasis I don't know if they actually do dots or sesame seeds or whatever in ... Mongolian. The picture in the link uses a line for emphasis. ... For Ruby, it is clear that it is always on the right hand side. I asked three Chinese experts ... this morning how this works. In Chinese the line is used for identifying names of people, ... book titles etc and it goes on the left hand side unlike Japanese or Mongolian. The text ... emphasis may go on the left hand side but typically would go on the opposite side from ... the line used for book titles etc. They said you don't see much vertical subtitling in Chinese ... at all, and where it is used the line progression is right to left rather than left to right. ... In Mongolian you would expect the line progression to be left to right. ... My worry is that in most usage these days, tblr is for Mongolian, but if we are using ... before or after then for every Mongolian subtitle you have to make sure you get things ... on the correct side. It is not quite so straightforward because in some cases things move. ... As I understand it in Mongolian the line goes on the left and the Ruby goes on the right. ... It seems unfair for these, the main users of this orientation, to have to set a different ... default. It is not based on the language but on the language model. Glenn: In a TTML2 document you just have to put one element up in the head of the ... document so it is not much of a burden to do that and it makes processing more ... consistent and reduces the implementation special cases to worry about. Pierre: Can we add a note pointing out Richard's observations? Glenn: That would be quite appropriate, and to advise on what to do. Would that work? r12a: That would help, yes. I agree it's only one change to make. The bigger concern is that ... it does not address the sensitivities of people who may think there is a western or a ... Chinese bias being introduced. Glenn: I understand that very well! ... I am also sensitive to implementers, and testing. It seems like an awful lot of work ... to change the behaviour to make the default sensitive to the writing mode and also as ... I have pointed out in the case of Chinese I have on many occasions seen tblr including ... Ruby on the left and text emphasis on the left. r12a: By the way text emphasis does typically occur on the left hand side but the Ruby ... would be very unusual especially if you are using Bopomofo so that's a difference between ... Japanese and Chinese. Glenn: One question: at least in Mongolian proper ("outer Mongolian") Cyrillic was the <r12a> [15]https://github.com/w3c/type-samples/issues/56 [15] https://github.com/w3c/type-samples/issues/56 Glenn: primary script used for many years, has there been much movement to going back to ... the primary script? r12a: There is a strong desire to go back to the original script and I can produce lots of ... examples quite easily. ... I have seen books and booklets in Mongolian, I don't know about newspapers. Glenn: It would be a useful point of note to hear what someone in a standards body in ... the mainland's position would be because they have an official use of the script for ... "inner Mongolia" on the Chinese side. r12a: Most of my conversation has been with them actually. Nigel: So one possibility is to note the option to use the initial element and another is ... to make the default writing mode dependent - is that what CSS uses? r12a: Yes, in CSS the terms are "over" and "under" and they are writing mode dependent. Glenn: We could add over and under, either now or at some point in the future. My ... preference is to add a note and not add over or under at this time. Nigel: Does that mean that the mapping to CSS will be harder if we do not add over and under now? Glenn: I'd have to think... If we add over and under in the future, how would that impact ... the default now? The default now is based on auto which already has a quirk based on ... the number of lines - it maps to "outside" for two lines which is definitely not in CSS, ... and that came about from subtitle usage in Japan, not considering Mongolian usage. ... If it is not two lines then it maps to "before". Even with what we have now it is not unlikely ... that you would end up specifying a different behaviour e.g. "before" if you don't want ... this outside behaviour. If we added over and under in the future that would not change ... the default setting so you would still end up having to specify e.g. over instead of before ... for the CSS behaviour now. Pierre: My 0th order concern that there is nothing missing in TTML is met. ... The choice of writing-mode dependent default is a departure from TTML so more ... error prone. Adding over and under seems a middle ground. Adding a note seems ... worthwhile regardless. The main point is that CSS diverged from XSL and TTML so we ... have to cover those gaps as we move along. Nigel: And you did not have a concern about mapping to CSS? Pierre: There is a static mapping, so no. Nigel: The group's view seems to be to go with a Note primarily, and that could be enough ... to address the sensitivies of Mongolian readers and writers? r12a: If you add the note then I will seek review of it. Pierre: It is more than that, the use of initial is the ultimate way to address cultural or ... personal preferences. Glenn: I agree. The question should be "can you live with specifying initial?" Nigel: Ok I have added a note to the issue about this. ... Now lets move on to: [16]https://github.com/w3c/ttml2/issues/254 [16] https://github.com/w3c/ttml2/issues/254 Nigel: Have we actually just discussed this? r12a: The default preference may be different for Ruby and lines and text emphasis. In ... Chinese the most likely thing is text emphasis on the left hand side regardless of lr or rl ... but Ruby would be on the right hand side. I'm not sure that the answer for #240 would ... provide the answer for this but I think that the final result is going to be the same. Nigel: Is this the same as the discussion we just had? r12a: It is, essentially the same and the thing that lead to #240. Nigel: Ok I've added a note to the issue on that. ... Moving on to #253 [17]https://github.com/w3c/ttml2/issues/253 [17] https://github.com/w3c/ttml2/issues/253 Nigel: My question is do we have enough data to agree if we need to support bopofo Ruby? r12a: We still need data about if bopomofo is used in subtitles for Chinese and I was not ... able to get an answer to this yet when I was talking to people from Taiwan. At a minimum ... we should not close out the possibility of adding it later if the need for it becomes stronger. Glenn: I don't see why we could not add support for character based Ruby in the future, ... either in IMSC or in TTML2. I've been watching [scribe missed audio] ... I wouldn't rule ... out the use for pedagogical purposes but I don't have any data points there. r12a: It is very much a Taiwanese thing, not used in mainland China. Nigel: Are we expecting a response to the question on the issue any time soon? r12a: I will take an action for myself to prompt him on that. Dae: I think this is a primary candidate for TTML.next - our major subtitle authors ... based in China never use bopomofo. r12a: One possibility is that again you could put a note in saying we know we do not ... support bopomofo ruby at the moment and even add a request for contact if anyone ... thinks it is important. At least this shows we have not been ignorant of it. Glenn: That's a good point. Nigel: Okay I have added a comment on the note explaining our default position on this ... in the absence of further data points. [18]https://github.com/w3c/ttml2/issues/253#issuecomment-288760 842 [18] https://github.com/w3c/ttml2/issues/253#issuecomment-288760842 Nigel: Thank you very much for joining us today Richard! Glenn: Thanks for your input Richard. r12a: Thanks, bye! Nigel: In the time remaining can we very quickly cover the open pull request on TTML1? [19]https://github.com/w3c/ttml1/pull/233 [19] https://github.com/w3c/ttml1/pull/233 Glenn: I believe this is something Andreas posted. I need to coordinate it with TTML2 actions ... around the same text and make sure we are consistent and we have dealt with the errata ... aspects of it. Andreas: I think this makes sense. It has been open for 1.5 months so I think we should ... make progress on this to clear it from the table. Nigel: Looking at the history this is an action for Glenn then. Glenn: My only concern there is I will probably edit it to shorten it quite considerably. It ... seems overly detailed as a note because I don't think we want to dive into some of the ... language around XSL-FO semantics like large allocation rectangle etc so I would like to ... say the same thing paraphrased to make it shorter. Andreas: Then this means it is not actually accepted. Nigel: We'll have to review the edited version. Pierre: As a matter of process it is weird to have a pull request open for so long. What is ... the deadline for getting this addressed? ... It is weird for the group to agree the essence of the pull request and then have nothing happen. Glenn: We need to have the language the same in TTML2 and TTML1 so there is a dependency. ... We haven't prioritised any updates on TTML1; TTML2 has a higher priority. Nigel: We generated a big list of discussed and agreed issues for TTML1 in London. Glenn: We don't have a schedule for a third edition. Nigel: We don't have an agreed date for it. Glenn: As soon as I have it addressed in TTML2 I will backfill into TTML1. Andreas: I would like to support what Pierre said - we are quite fast in merging pull requests ... in TTML2 and I would like to do the same in TTML1 also. Pierre: Can we prioritise this one? Glenn: Sure I will put it to the top of my list and do it today, in TTML2 and TTML1. Nigel: OK thanks. IMSC Nigel: Thank you to Pierre and Thierry for publishing the WD for WR. [20]https://www.w3.org/TR/2017/WD-ttml-imsc1.0.1-20170322/ [20] https://www.w3.org/TR/2017/WD-ttml-imsc1.0.1-20170322/ Nigel: That was published yesterday, and Thierry posted many messages to other W3C ... groups requesting wide or horizontal review. ... But not all groups - Thierry you need some input from the group? Thierry: I'm missing privacy and security and TAG. Nigel: Please could you do a first draft of the privacy and security questionnaire for the ... group to review? Thierry: Yes I will. Nigel: Okay, adding the issue... [21]https://github.com/w3c/imsc/issues/222 [21] https://github.com/w3c/imsc/issues/222 Nigel: Thank you, and I have an action as previously agreed to send outgoing liaisons to ... the usual groups based on the text that we agreed a while back. I think only the review ... response date needs to be edited. ... I will be able to do that probably on Monday if I can't find time to do it any sooner. Thierry: So we might receive some comments - I propose to track those and then if we ... need to come up with a document at the end then ... Pierre: Can we do it through GitHub with a Wide Review comment tag on the issue? Thierry: Do you want to use the Last Call tool or do something different? Pierre: I assume we should track it on GitHub. Is there a downside to that? Thierry: No I don't, at some point we need a disposition of comments document. Pierre: I assumed we could use labels on GitHub and then generate say a PDF to be the ... document. Thierry: We need the comment, our resolution, and agreement from the commenter. Nigel: I would suggest recording the issues in GitHub and also using something like the ... Last Call tool to generate the documentation that we need. Thierry: I am happy to maintain both, and I don't anticipate hundreds of comments. Pierre: What is important is that every change we make to the document is tied to an ... issue in GitHub. ... If you prefer to use the LC tool we can probably create a bunch of GitHub issues at the ... end and link back to the tool comment if we can, but a lot of folk look at GitHub to see ... what issues are open. My intuition is to enter the issues on GitHub to be transparent. Thierry: We'll start like that and if needed and there are a lot of comments I will use the ... tool. Even with 10 comments it is faster to do it manually. Nigel: Great I think that is everything for today and we have hit time, so thank you everyone. [adjourns meeting] Summary of Action Items Summary of Resolutions [End of minutes] __________________________________________________________ Minutes formatted by David Booth's [22]scribe.perl version 1.152 ([23]CVS log) $Date: 2017/03/23 16:05:52 $ [22] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm [23] http://dev.w3.org/cvsweb/2002/scribe/
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