14:00:04 RRSAgent has joined #tt 14:00:04 logging to http://www.w3.org/2017/10/19-tt-irc 14:00:06 RRSAgent, make logs public 14:00:06 Zakim has joined #tt 14:00:08 Meeting: Timed Text Working Group Teleconference 14:00:08 Date: 19 October 2017 14:00:46 Present: Nigel 14:00:48 scribe: nigel 14:00:50 Chair: Nigel 14:00:53 Regrets: None 14:01:21 pal has joined #tt 14:01:35 Present+ Cyril 14:01:50 mike has joined #tt 14:02:01 Present+ Pierre 14:02:54 Present+ Mike 14:03:57 Present+ Mike 14:05:02 Regrets+ Andreas 14:06:49 Topic: This meeting 14:07:05 cyril has joined #tt 14:07:31 Nigel: Today, we have TPAC planning (if there is any - reminder there are 2 calls between 14:07:36 .. now and the face to face meeting). 14:07:45 Present+ David_Ronca 14:08:02 David_Ronca: [will be present for first hour only] 14:08:28 Nigel: That's apart from today. 14:09:07 .. We should review Cyril's compatibility document, and look at TTML2 Wide Review issues, 14:09:11 .. to work out our disposition. 14:09:35 .. For IMSC, there were some comments raised on the vNext Requirements doc to go through. 14:09:47 .. Then hopefully resolve to publish as a WG Note 14:10:15 David has joined #tt 14:10:16 .. We have some pull requests to look at for TTML2 also. 14:11:11 .. I don't see anyone who can discuss WebVTT today but we will try to get to that if they join. 14:11:23 .. Any other topics to mention, or other business? 14:11:26 group: [no] 14:11:38 Pierre: [will have to drop off after the first hour too] 14:11:55 Cyril: In IMSC 1.1 we should revisit the issue about subsetting of TTML2. 14:12:16 Pierre: I thought that was the primary topic. 14:12:33 Nigel: I see this as two questions (or three): 14:12:43 .. 1) Compatibility between TTML1 and TTML2, 14:12:59 .. 2) Inclusion of IMSC features in TTML2 14:13:12 .. 3) Subsetting of TTML2 to generate IMSC vNext 14:13:59 Topic: TPAC planning 14:14:20 Nigel: I don't think there's anything to do here? Not everyone has put their names on the wiki yet. 14:14:44 Topic: TTML1 and TTML2 compatibility in practice 14:15:03 Cyril: I want to go through the document, but not in too much detail (that's for offline). 14:15:15 .. Just for recapping: I did a side by side manual comparison of TTML1 and TTLM2 to 14:15:30 .. identify changes, and then assessed if they are critical for compatibility, i.e. whether an 14:15:44 .. TTML1 document would be rendered by a TTML2 processor in an acceptable way according 14:15:58 .. to TTML1, taking into account fonts, rendering etc. 14:16:06 .. I hope you all had a chance to look at the document. 14:16:18 .. My general feeling after this is that there are some subtle differences but either TTML2 14:16:33 .. is more precise because TTML1 was ambiguous, in which case it's okay, TTML2 rendering 14:16:47 .. would be acceptable as a TTML1 rendering; OR there are features that are different, but 14:17:13 .. for features that are specified in TTML1 but not used in IMSC1, like pixelAspectRatio, 14:17:38 .. that is, the features with differences are not actually used. 14:18:17 .. The problems I identified are the orange ones - pixelAspectRatio, direction (TTML2 14:18:37 .. fixes a TTML1 problem, maybe a good candidate for TTML1 Third Edition), overflow - a 14:18:54 .. MUST statement has been removed in TTML2, then a section on computed style set 14:19:08 .. processing, where a filtering step in which TTML1 does not filter elements but 14:19:20 .. TTML2 does filter them, so the computed value would be different. My understanding is 14:19:31 .. that's a problem in TTML1, so could be fixed in TTML1 Third Edition. That's it. 14:20:06 Nigel: For `` exclusion I think that was an omission in TTML1. 14:21:22 Mike: This all came about to ensure IMSC 1.1 compatibility with TTML2. The exclusion of 14:21:26 .. set becomes a problem. 14:22:14 Nigel: You should check the impact of this - I believe it was an oversight in TTML1 and 14:22:23 .. you could say it was implied. 14:22:46 Pierre: We came to a decision on this - see ttml1#216 - the plan is to include it in TTML1 14:23:01 .. Third Edition. It's just a bug in TTML1, and would have been in TTML2 if we had not found it in TTML1. 14:23:16 Cyril: I'd like to know if anyone thinks I've missed something? 14:23:29 Pierre: A good thing to check is if every difference has an issue in TTML1. 14:23:35 Cyril: I'll do that to make sure. 14:23:48 Pierre: If yes then you have agreement, otherwise we should go over them. 14:24:03 Cyril: Assuming I haven't missed anything, do you share the feeling that there's no 14:24:05 q+ 14:24:16 .. significant gap between TTML1 Third Edition and TTML2 and that the renderings can be compatible? 14:24:18 ack pal 14:24:30 Pierre: That was the goal from the beginning. So I agree with you - that's why those issues 14:24:40 .. were filed against TTML1 and TTML2 was corrected accordingly. 14:25:15 Mike: I'm not sure what "significant" means here - we've identified some areas that could 14:25:37 q+ 14:26:21 .. be done differently depending on which version is being used. 14:26:58 .. We still need the [statement about no differences] 14:27:11 Nigel: Why do we need that statement? Put another way, if TTML1 is ambiguous and 14:27:17 .. TTML2 is less ambiguous, is that a problem? 14:27:33 Mike: If we publish TTML1 Third Ed and then the differences are removed, it's not a problem. 14:27:36 ack pal 14:27:53 Pierre: I'm with Mike in the sense that we should capture that goal, because we seem to 14:28:04 .. keep coming back to it even though everyone agrees that its the goal. I don't understand 14:28:08 .. the reluctance. 14:28:45 Nigel: My reluctance is "unintended consequences" - especially if there are multiple goals 14:29:07 .. and they could come into conflict, it's a hostage to fortune if we state them; it's the work 14:29:21 .. of this WG to resolve them, and if we intend TTML1 Third Edition and TTML2 to be 14:29:39 .. compatible in the way that we agree, we just make it so, without having to state it in the spec. 14:31:31 Mike: This isn't about us, it's about the readers of the spec. 14:31:40 Cyril: There's section §3.4.2 in the spec about backwards compatibility. 14:32:27 Mike: I had an action to propose some wording. 14:32:36 Nigel: That's issue ttml2#458. 14:32:40 Cyril: Where's the actual text proposal? 14:34:47 Nigel: The only tonal difference I want to see are that we don't state a guiding principle 14:34:56 .. but a statement of our understanding of what we have achieved. 14:35:12 Cyril: Why don't we put something like I put in the top of my analysis document, that 14:35:28 .. a TTML1 document processed by a TTML2 processor would produce an acceptable 14:35:50 .. result when processed by a TTML1 Third Edition processor. 14:36:24 .. I don't care where that goes - in §3.4.2 or in the Scope. 14:36:40 Nigel: We have a dependency on TTML1 Third Edition here, which needs some work on it. 14:37:17 Mike: We're not jumping to TTML2 Rec tomorrow so we have some time. 14:37:42 .. I know Glenn has done some work on TTML1 Third Edition. 14:37:52 Pierre: May I encourage the Chair to follow up with Glenn offline? 14:37:56 Nigel: Yes, I will. 14:38:11 Mike: It doesn't change the principle here - we can still state the same principle regardless 14:38:17 tmichel has joined #tt 14:38:18 .. of TTML1, because that's our intent. 14:38:21 Cyril: I agree. 14:39:13 Present+ Thierry 14:39:33 Cyril: If the wording is about TTML2 being designed for acceptable results except for edge 14:39:41 .. cases X, Y and Z would that work for you Nigel? 14:39:44 Nigel: Yes, sounds good. 14:39:52 Cyril: Everyone else? 14:39:56 Mike: Yes, sounds good. 14:40:04 Cyril: I'll propose text in ttml2#458. 14:40:58 Topic: TTML2 Wide Review 14:41:00 action-508? 14:41:00 action-508 -- Thierry Michel to Check if there are editorial/substantive labels for ttml2 issues and add if not. -- due 2017-10-12 -- OPEN 14:41:00 http://www.w3.org/AudioVideo/TT/tracker/actions/508 14:41:44 Thierry: I don't think I've done that yet. 14:41:50 Topic: IMSC 14:42:24 Pierre: There's been a lively discussion on the reflector; now we've addressed the TTML1/TTML2 14:42:39 .. compatibility, the outstanding issue is for IMSC 1.1 to be a subset of TTML2. It's been in 14:42:49 .. the requirement of IMSC 1.1. 14:43:00 Cyril: Please clarify "subsetting"? What is "subset"? 14:43:15 Pierre: It means it doesn't introduce any extension, it only constrains features of TTML2. 14:43:32 .. I thought that was the goal, but maybe that's the first question. Then there are two options 14:43:46 .. for getting there. One is to hoist into TTML2 the syntax of IMSC 1.0.1; the other is to 14:43:57 .. deprecate the syntax of IMSC 1.0.1 and use the syntax of TTML2. 14:44:13 .. First I want to check that IMSC 1.1 is supposed to be a subset of TTML2? 14:44:27 Cyril: Yes 14:44:40 Mike: It's contingent on the previous discussion and arriving at some language. 14:48:23 Nigel: I'm concerned both about the cleanliness and tidiness of TTML2 and the difficulty 14:48:34 q+ 14:48:57 .. of content providers creating documents that work in current IMSC 1.0.1 players and not 14:49:24 .. having to produce multiple flavours of the same document. 14:49:59 Pierre: What about IMSC 1.1 being a pure subset of TTML2 with the exceptions of IMSC 1.0.1 14:50:13 .. features that are deprecated for backward compatibility. That's what the requirements 14:50:15 .. currently state. 14:50:24 Cyril: I don't understand what this means. 14:50:45 Pierre: Take any IMSC 1.0.1 extension, say ittp:aspectRatio - we have two options, one to 14:50:58 .. import into TTML2 the syntax from IMSC 1.0.1, and stop there; the other option is to 14:51:12 .. support but deprecate the IMSC 1.0.1 feature and support the TTML2 feature. Those 14:51:41 .. options exist for every extension. 14:51:52 Nigel: I would also state what the mapping to the new syntax is and what the rule is if 14:51:55 .. both are present. 14:52:15 Pierre: It's even more complicated - fillLineGap doesn't say the same thing in TTML2 as 14:52:19 .. in IMSC 1.0.1. 14:52:29 .. For each extension, we can figure out what we want to do. 14:52:32 Nigel: Seems reasonable. 14:52:49 Pierre: I think the goal is for IMSC 1.0.1 to be a subset of TTML2. 14:53:23 s/IMSC 1.0.1 to be a subset of TTML2/IMSC 1.1 to be a subset of TTML2/ 14:54:37 Nigel: If we want to end up with IMSC 1.1 extension features having a mapping to TTML2 14:54:56 .. then we could do that either by choosing the option and putting into TTML2, so TTML2 14:55:12 .. can support IMSC 1.0.1 syntax, or we could state the rules directly into IMSC 1.1 and not 14:55:17 .. add the extensions into TTML2. 14:55:35 David_Ronca: I think I'm with Pierre that we can add the IMSC 1.0.1 features to TTML2 and 14:55:39 .. use a deprecation model. 14:55:57 Nigel: So you'd put the IMSC 1.0.1 extension features in TTML2 as deprecated? 14:56:25 David_Ronca: No, I don't think they need to be in TTML2. 14:56:35 Nigel: So you'd put the deprecation language in IMSC 1.1 then? 14:56:53 David_Ronca: Yes because the extension features wouldn't be in TTML2. 14:57:05 .. There are two ways forward, one pure TTML2 and one backwards compatible with IMSC 1.0.1 14:57:17 .. and they would both be supported by an IMSC 1.1 processor. 14:57:35 Pierre: Just to clarify, you're not objecting to move extensions into TTML2. right? 14:57:49 David_Ronca: It would be weird to put ittp:aspectRatio into TTML2 but for things that don't 14:58:06 .. exist in TTML2 they could be added. 14:58:19 Pierre: I'd like the flexibility to deal with each extension one by one. 14:58:32 David_Ronca: I agree with that. I'd expect TTML2 aspect ratio to have equivalent functionality 14:58:44 .. to IMSC 1.0.1 ittp:aspectRatio, and not have both in TTML2. 14:58:57 Pierre: At TPAC we will have to ensure that the TTML2 semantics achieve what is in IMSC 1.0.1 14:59:04 .. I'm proposing taking each extension one by one. 14:59:10 David_Ronca: I agree we have to do it that way. 14:59:52 Nigel: I think the result of that is that IMSC 1.1 would be a subset of TTML2 with the 14:59:56 .. exception of deprecated features. 15:00:01 Cyril: yes 15:00:09 Pierre: That's what the requirements say. 15:00:23 Cyril: And for each deprecated feature there is a mapping to a TTML2 feature. 15:00:34 Pierre: Each one may take some discussion. 15:00:42 Cyril: There are only 6 right. 15:00:48 s/t./t? 15:01:18 Pierre: As a result of this exercise some changes will be needed in TTML2. 15:01:34 .. I'm particularly thinking about fillLineGap. There have been some exchanges about that 15:01:45 .. in IMSC 1.0.1 and having different semantics in TTML2 would be really damaging. 15:01:58 .. My plan is to proceed with a game plan for the group to review for each extension. 15:02:01 Nigel: Sounds good. 15:03:36 Cyril: Mike, are you still concerned that an IMSC 1.1 document with tts:disparity might be rendered differently? 15:03:56 Mike: Given the history I'm sceptical but I'm also optimistic that you will come up with the right language! 15:03:59 Cyril: Ok 15:06:00 Topic: Add equivalent CSS properties to style attributes #406 15:06:05 github: https://github.com/w3c/ttml2/issues/406 15:06:23 Nigel: A couple of things here. First, I opened a Pull Request for review by anyone who can. 15:06:45 -> https://github.com/w3c/ttml2/pull/470 Pull request 15:07:12 Nigel: And Cyril, you found transform::skew for fontShear. 15:10:20 .. There are two actions. First, to update the CSS Requirements wiki to point to it; 15:11:05 .. second to create an issue linking to #406 mapping fontShear to transform::skew. 15:11:11 Cyril: I will create that issue. 15:11:21 Nigel: I don't mind doing the work to add it to the pull request. 15:11:27 Cyril: How can we review the pull request? 15:12:01 Nigel: I committed the regenerated HTML so it can be reviewed, so you can open it at: 15:12:32 -> https://rawgit.com/w3c/ttml2/178659af16ee4b8514adc7f16ea1ca786fcf38a1/spec/ttml2.html 15:12:45 Cyril: Great, thank you. 15:13:08 .. I'll have to review that. 15:13:19 .. So in principle you're building this annex based on the wiki page? 15:13:39 Nigel: Yes with the additional filter of the CSS 2017 Snapshot so I check each feature 15:13:45 .. against the latest snapshot version of the spec. 15:14:14 Cyril: At some point there should be a top level thing in the wiki page pointing to the 15:14:22 .. new section in TTML2 in case they diverge. 15:14:30 Nigel: Good idea, when we've merged the pull request. 15:14:52 .. However it's much easier to read in the wiki page so it might be worth updating. 15:15:05 Cyril: just having a sentence pointing to the more accurate information would be good. 15:15:07 Nigel: +1 15:18:14 Nigel: On this pull request I'd be interested in any suggestions for better formatting. 15:18:32 .. The new section N.2.1 has a bunch of small tables, which blend into each other a bit. 15:18:47 Cyril: Yes it's not very compact. 15:19:02 Nigel: I agree - it has the right information in it I believe, but I don't like how it looks. 15:20:48 Topic: Reference CSS color semantic #413 15:20:56 github: https://github.com/w3c/ttml2/issues/413 15:21:27 Nigel: It looks like Glenn doesn't want to add anything, but I don't know why we don't 15:21:51 .. just align with the CSS set while also keeping the additions already defined in TTML1. 15:22:53 Cyril: Eventually we should have the same list as in CSS, so we may need to ask CSS to add some new names. 15:23:04 Mike: I don't see any harm, and would be happy to get to alignment. 15:23:19 .. Taking out named colors would have no benefit. It's trivial enough to translate the 15:23:29 .. handful of named colors into the sRGB hex representation. 15:24:03 Mike: §4.2 of the SVG 1.1 spec has a big table of named colors. 15:24:11 Nigel: I think it doesn't include transparent. 15:24:20 Mike: It would be a disservice to remove named colors in TTML2. 15:24:24 Nigel: +1 15:24:36 Mike: It would make TTML1 documents non-conformant that would be a bad idea. 15:24:57 Cyril: SVG supports CSS2 plus an expanded list of names. I think it should not be too difficult 15:25:08 .. to have the CSS WG adopt the SVG color keywords. I might be wrong! 15:25:39 .. On top of these we're just defining transparent, because there's no alpha channel defined 15:26:10 .. in the SVG keywords. 15:26:52 Mike: We have to be careful about defining transparent because it is the initial value of the 15:26:57 .. tts:backgroundCOlor. 15:27:51 Nigel: I think we have consensus to get align with the CSS color set while not removing any existing colors. 15:28:00 Mike: I'm okay with that, if the goal is to better align with CSS. 15:28:17 Pierre: I'm not against it but I see no advantage in adding "orange'. 15:28:38 .. Recall that as long as there is a delta between CSS and TTML a lookup table is still needed. 15:28:44 .. I would rather not touch it. 15:30:16 Nigel: I think it's about direction of travel. 15:30:34 Pierre: Adding "orange" now would cost implementors time for no benefit, because we still 15:30:50 .. wouldn't be aligned with CSS, so that's no benefit now. 15:31:48 Nigel: I can see that, maybe we should go to CSS WG and ask them to align named colors 15:32:04 .. with SVG, and then defer any change to TTML until that decision has been made. 15:32:21 Cyril: I like that. 15:32:23 Pierre: +1 15:32:46 SUMMARY: We will not add "orange" now but ask CSS WG to align named colors with SVG and then look at this again. 15:34:13 Topic: Region constraints are the same as in IMSCvNext #262 15:34:23 github: https://github.com/w3c/imsc/issues/262 15:34:41 Nigel: this is also about imsc#260 15:35:45 .. The issue here is about the differences between IMSC 1.0.1 and IMSC 1.1 and about region constraints. 15:36:13 Pierre: The idea is to say IMSC 1.1 is IMSC 1.0.1 verbatim unless there's a divergence. 15:36:36 .. Whatever text helps I'm happy to put that in. 15:37:13 -> https://rawgit.com/w3c/imsc/297dcb3f5aa35889029bb10e5def87ca089407aa/imsc1/spec/ttml-ww-profiles.html draft proposal 15:38:50 Cyril: In the light of the discussion on TTML2 we will need to change that section. 15:39:08 .. We said we'd go for a model where IMSC 1.1 imports features from IMSC 1.0.1 and TTML2 15:39:24 .. and the IMSC 1.0.1 extensions to TTML1 are deprecated where there are alternatives in TTML2. 15:39:31 Pierre: That's a different issue but yes. 15:40:00 Cyril: The compatibility with 1.0.1 documents is true but is not always the preferred way, in the case of deprecations. 15:40:38 Pierre: #260 is handled by the appendix [L2] 15:40:47 Cyril: The pull request is okay to satisfy the two issues. 15:41:10 Pierre: except for Nigel's concerns about the new text. 15:41:30 .. If we removed that new text would the issues still be addressed? 15:41:47 Cyril: I would prefer for each section a sentence saying "this is the same as in IMSC 1.0.1" 15:41:57 Pierre: We don't do that in TTML, and some sections are numbered. 15:42:07 .. Purely for an implementor, they should be able to review the differences. 15:42:28 Nigel: Can I propose a minor change of wording, to: 15:43:00 .. Relative to [ttml-imsc1.0.1] any additions or deprecation of features are summarised at Append L. 15:43:06 Cyril: Okay, good. 15:43:11 Pierre: Fine with me. I'll change it. 15:43:33 Cyril: I'll raise a separate issue to clarify the relationship with TTML2 in the Abstract, so it doesn't get lost. 15:43:36 Pierre: OK 15:44:01 SUMMARY: Update wording in Abstract. 15:49:34 Topic: Is #ruby necessary, or #ruby-non-nested sufficient? #2 15:49:40 github: https://github.com/w3c/imsc-vnext-reqs/issues/2 15:49:59 Nigel: I was able to ask someone from NHK in Japan about this yesterday and he provided 15:50:17 .. a data point that in his opinion ruby on ruby is never used. He did think there may be a 15:50:25 .. use case for textEmphasis on ruby though. 15:51:14 Topic: IMSC vNext requirements 15:51:36 Nigel: There's no issue for this yet, but the ARIB-TT use case mixes image and text in the 15:51:49 .. same document, and my contact at NHK said that's really important for them, so this 15:52:01 .. may be relevant for us thinking about image vs text profile. 15:52:14 Mike: Currently that's forbidden of course. At odds with this are all the changes we're 15:52:28 .. making in IMSC 1.1, I think, that it will obviate the need for image profile at all. 15:52:46 Nigel: Good point, however his use case is that even in subtitles and captions they place 15:53:06 .. e.g. company logos next to the names, so imagine, say a Dolby logo or a Nike swoosh etc 15:53:12 .. placed next to the company name. 15:53:54 .. Apparently this is a matter of reflecting current practice. 15:54:05 Mike: That's an interesting situation - taking it to the extreme we could merge the two 15:54:06 .. profiles. 15:54:12 .. It would simplify the spec actually. 15:54:39 .. In US closed captions there's a symbol that folk came up with that doesn't exist in Unicode. 15:54:47 Nigel: Did they ask to add it to Unicode? 15:55:08 Mike: I don't think so. It's 2x "C" characters in the symbol to represent closed captions. 15:55:36 .. These days people just use (CC). Anyway it would be a way to implement it. 15:55:56 .. It's an interesting use case to put a non-Unicode symbol in on the fly. 15:56:10 Pierre: Another example I've been given in SE Asia is a symbol for a ringing telephone when 15:56:31 .. there's the sound of a telephone ringing. With a simplistic left-right-left animation. 15:56:54 Mike: Sounds like we need to file it as an issue and discuss it more. 15:56:58 Nigel: Yes, I will. 15:57:05 Pierre: It would be really good to get ARIB to contribute. 15:57:25 Mike: Especially if we have to merge Text and Image profiles to achieve it. 15:58:30 Topic: CLDR 15:58:46 Nigel: The same person suggested one way forward is to try to add the caption characters 15:58:56 .. into ISO 10646, which would have to be done quickly. 15:59:24 .. My sense is that the status quo is not ideal but is okay. 15:59:31 Pierre: It's not been a complaint so far. 16:00:48 Mike: Is there an issue for this? 16:01:12 Nigel: No, there's no action to take until CLDR does something. 16:02:34 .. The issue here is that IMSC 1 Appendix B refers to CLDR and we asked Unicode to keep 16:02:45 .. a record of code points commonly used in subtitles and captions as part of the CLDR 16:02:59 .. initiative, but they haven't really dealt with the request yet, at least we haven't seen any 16:03:03 .. usable outcome. 16:03:08 Topic: Meeting end 16:03:16 Nigel: OK, thanks, [adjourns meeting] 16:03:20 rrsagent, make minutes 16:03:20 I have made the request to generate http://www.w3.org/2017/10/19-tt-minutes.html nigel 16:07:18 Regrets- None 16:09:26 s/tonal difference I want to see are that/tonal difference I want to see is that 16:13:01 s/.. new section in TTML2 in case they diverge./Cyril: new section in TTML2 in case they diverge. 16:13:51 s/tts:backgroundCOlor/tts:backgroundColor 16:14:19 s/consensus to get align with the CSS color/consensus to get alignment with the CSS color 16:15:15 s/Append L./Appendix L. 16:17:21 s/OK, thanks, [adjourns meeting]/OK, thanks everyone, see you next week. [adjourns meeting] 16:17:26 rrsagent, make minutes 16:17:26 I have made the request to generate http://www.w3.org/2017/10/19-tt-minutes.html nigel 16:20:03 ScribeOptions: -final -noEmbedDiagnostics 16:20:04 rrsagent, make minutes 16:20:04 I have made the request to generate http://www.w3.org/2017/10/19-tt-minutes.html nigel 16:51:42 Zakim has left #tt 18:03:20 pal has joined #tt