14:59:26 RRSAgent has joined #tt 14:59:26 logging to https://www.w3.org/2020/05/28-tt-irc 14:59:28 RRSAgent, make logs Public 14:59:30 Meeting: Timed Text Working Group Teleconference 15:01:00 scribe: nigel 15:01:03 Agenda: https://github.com/w3c/ttwg/issues/117 15:01:12 Previous meeting: https://www.w3.org/2020/05/21-tt-minutes.html 15:01:20 present+ 15:01:25 Present: Vladimir, Nigel, Atsushi 15:01:48 Chair: Nigel 15:02:04 Present+ Pierre 15:02:43 Present+ Andreas 15:03:03 Present+ Gary 15:04:07 Vladimir has joined #tt 15:04:17 present+ 15:04:27 Topic: This meeting 15:05:03 Nigel: Today we have some IMSC topics: PR transition, vNext requirements window, 15:05:27 .. and ARIB issues. We also have a placeholder for TTML2 IR but I don't think there's 15:05:29 .. much to discuss there. 15:05:43 .. AOB or points to remind the Chair to make sure get covered? 15:06:14 Pierre: Admin: can we talk about the pull requests that are updating links on the published Rec.? 15:06:28 .. They say the PR is not for release. Can we take 5 minutes on this. 15:06:29 cyril has joined #tt 15:06:32 Nigel: Right, on IMSC? 15:06:42 Pierre: Yes, old IMSC, 1.0.1, 1.1 15:06:48 Present+ Cyril 15:07:23 Topic: IMSC 1.2 CfC to request transition to PR 15:07:33 Nigel: Reminder that the CfC is open until 5th June. 15:07:46 -> https://lists.w3.org/Archives/Public/public-tt/2020May/0033.html CfC to request transition of IMSC 1.2 to PR 15:08:04 -> https://github.com/w3c/transitions/issues/245 Draft transition request 15:08:17 Nigel: Anything to raise on this topic? 15:08:41 Topic: IMSC vNext requirements window 15:08:59 Nigel: 2 current drivers for this (so far): 15:09:15 .. 1. Netflix requirements provided by Cyril a few weeks back 15:09:19 .. 2. ARIB liaison 15:09:25 .. Of course there may be other requirements. 15:09:43 .. Historically we have opened a window for people to register new requirements, 15:09:54 atai has joined #tt 15:09:55 .. and I propose doing the same thing again. The question is the time window for 15:09:58 .. doing this. 15:10:05 .. Any proposals? 15:10:42 Pierre: It would help if we as a community try to guess what the scope would be. 15:10:50 .. It's hard before calling for requirements, but it would help on the timing. 15:11:01 .. We have contributions from Disney and Netflix that are very specific. 15:11:13 .. We have ARIB which are very specific too and potentially the changes will be more significant. 15:11:17 .. Do we foresee anything else? 15:11:33 Nigel: I don't think I'm aware of any right now. 15:12:26 .. Something else that's relevant is that CSS is working on Ruby stuff at the moment 15:12:34 .. so we potentially have a sync point with their work. 15:12:43 (sorry for delay of my email on these, Nigel) 15:13:31 .. It feels that there may be a need to get agreement with multiple parties who might 15:13:36 .. take a while to respond. 15:13:41 Pierre: That's my feeling too. 15:13:54 .. We could adopt a new more flexible process where we could issue regular snapshots 15:14:06 .. and address issues as they come up, and decide to go to Rec or not Rec based on 15:14:11 .. how much we have. 15:14:28 .. If we do the traditional process for Rec like we did with IMSC 1.2 then it will be many months. 15:14:45 .. Question for Netflix is how urgent the fontShear work is for Rec publication. 15:14:57 Cyril: Good question, I would say the sooner the better because I want to avoid divergence 15:15:03 .. between actual implementation and content deployed. 15:15:14 .. But alignment with CSS is important, at the same time. 15:15:36 Pierre: Thinking out loud, a more iterative process is not incompatible with the idea of 15:15:45 .. a requirements window for establishing the scope of what we are doing. 15:15:50 .. We could freeze them now! 15:15:51 q+ just a comment on font shear in Japanese 15:16:03 Nigel: Not sure that's wise! 15:16:15 Pierre: I'm saying a short period, give people 2 months rather than 6. 15:16:19 ack ats 15:16:39 Atsushi: Comment on font shear. In i18n JLREQ task force we discussed font shear in 15:16:57 .. Japanese. But our knowledge was that font shear is not used in Japanese typography 15:17:08 .. so the TF decided not to state any requirement for font shear in JLREQ. 15:17:29 .. There is a common way to share font in Japanese typography used for publishing, 15:17:41 .. but we haven't had mutual agreement to state something to CSS WG yet. Just for information. 15:18:13 Cyril: That's interesting because it is exactly the opposite of the conversation I had with 15:18:29 .. the CSS WG member from Google who is from Japan. Koji Ishi maybe. The way we want 15:18:42 .. to do shearing in general is exactly the way it is done in Japanese typography so we 15:18:45 .. probably need to resolve that. 15:18:59 Atsushi: I think he mentioned the common way that font shear is done in recent Japanese 15:19:12 .. books. For input to CSS WG we may need to state something from some sort of 15:19:26 .. Japanese group. We failed to get to agreement in the JLREQ TF. To have some statement 15:19:44 .. we have to get input from a digital publishing group in Japan. I think I need to go back 15:19:56 .. to W3C Keio with this to complete the coordination. 15:20:39 Nigel: Another question about a requirements gathering phase is how we make it known 15:20:57 .. to the world. For example liaisons, as we have done previously, or a W3 blog post etc 15:21:08 .. It seems that some folk have come to us without any need for this. 15:22:10 .. Can we say now that the requirements window is open, and think about the closing date 15:22:18 .. and comms for it in the next few days? 15:23:01 PROPOSAL: The window for new requirements for future versions of IMSC after 1.2 is now open. 15:23:10 Nigel: Any objections? 15:23:18 +1 15:23:21 Cyril: no 15:23:24 Pierre: Sounds good to me 15:23:27 RESOLUTION: The window for new requirements for future versions of IMSC after 1.2 is now open. 15:23:41 (+1 means go ahead w/ no objection) 15:23:42 Nigel: Thank you. 15:24:52 Topic: [WR/ARIB] Mixture of text and image w3c/imsc#543 15:24:57 github: https://github.com/w3c/imsc/issues/543 15:26:22 Vladimir: Just for clarification, can we clarify exactly what they mean by inline graphics? 15:26:26 .. I'm not sure what they really mean. 15:27:37 Nigel: I understand it to be the kind of requirement where a company logo is inserted as 15:27:41 .. a graphic inline with text. 15:27:54 Vladimir: If someone wants to use a PUA code point in a user defined font for this, then 15:28:10 .. there is nothing we can do to stop them. I would say that would be a pretty unobjectionable 15:28:23 .. use of PUA codes because that's exactly what they're for. It's not going to hinder text 15:28:34 this IMSC requirement has an example https://github.com/w3c/tt-reqs/issues/15 15:28:40 .. processing or editing or search. I think that is not really a concern. 15:28:41 q+ 15:29:00 .. My concern was about GSUB substitution when you need to select the right form. 15:29:14 .. Anything that would be used to avoid doing standard processing for truly text content. 15:29:27 .. If they want to simplify things by missing some functionality I would say that's a bad idea. 15:30:33 q+ 15:30:43 .. They say that if GSUB is used before IVS is used then, it sounds like they want to simplify 15:30:56 .. by avoiding the need to do it. I think they just want to use PUA to see something they 15:31:07 .. want to be displayed. I would say that is a bad idea. It might work in a closed system 15:31:19 .. where the Timed Text is authored in the same environment but as soon as you attempt 15:31:33 .. to make it something more interoperable then you can't expect everyone to do it the same way. 15:32:01 Nigel: I wanted to note that PUA use can impact text processing, for example if a company 15:32:15 .. name is being substituted for its logo, then you might reasonably want to do things like 15:32:23 .. Text to Speech of the text, 15:32:29 .. Searching by text name, 15:32:42 .. all before any substitution. If PUA is used that really will break those use cases. 15:33:31 .. I think that is why we got to the point of using GSUB as a good idea before. 15:33:45 Vladimir: I absolutely agree with this. I don't think that PUA should be used in place of 15:33:52 .. a company name, because the implementation will break. 15:34:03 q+ Pierre 15:34:05 pal has joined #tt 15:34:05 ack n 15:34:27 Cyril: I agree with what Vlad said. I talked to my Netflix experts and they are of the same 15:34:37 .. opinion that we should avoid PUA as much as possible for all the reasons that were 15:34:49 .. explained. I am wondering how ARIB got the notion that we require GSUB, because I 15:34:59 .. don't think it is mentioned in the spec. Secondly maybe we should add something but 15:35:11 s/but 15:35:25 .. to limit the complexity of the implementation. I don't know if we can, for example limit 15:35:41 q+ 15:35:42 .. the font functionality required for IMSC. Are there profiles for this? I don't know. 15:35:52 ack v 15:36:05 Vladimir: Any attempt to do something to simplify implementation to let them off the hook 15:36:18 .. of a specific standardised feature, I think is not a good idea, because that feature may 15:36:26 .. manifest itself elsewhere that we cannot predict. 15:36:46 .. If normal text comes in and implementations drop a standardised case then 15:36:56 .. preprocessing would be needed. The short answer: I don't think it's a good idea to 15:37:06 .. simplify implementations if it goes against the standardised feature set. 15:37:12 ack Pier 15:37:25 Pierre: I think what we should do is get actual samples. It just occurred to me that there 15:37:36 .. are no examples of what they are trying to do. We should try to see how this works 15:37:48 .. in practice. We had a long thread on what we wanted to do with GSUB and we should 15:37:56 .. try it and assess how well supported and how easy it is. 15:38:09 .. We're at the point where we need to try it before we come up with a solution. 15:38:20 .. I would actually go back to ARIB and request a sample. 15:38:28 Nigel: That's a really good idea 15:38:40 Cyril: Are there tools that allow us to easily create fonts with a GSUB substitution? 15:38:59 Vladimir: Any font tool - most of them allow substitutions. You write your own rules as 15:39:13 .. a code entry, to substitute a sequence of glyphs. You don't know what those glyphs 15:39:36 .. represent. You just set a rule. Any sequence of input can be substituted. For example 15:39:44 .. a company name substituted by a logo is perfectly possible. 15:40:03 .. For example the Zapfino font, on most Macs I think, has a substitution entry that 15:40:16 .. substitutes the name of the font for the ligature. They do it just to showcase it. 15:40:26 .. You can substitute a ligature or anything else. 15:40:46 Nigel: That's an input sequence of code points? 15:40:55 Vladimir: The input is a sequence of unicode text points. 15:41:14 .. Then map those to glyph ids. 15:41:23 .. Then most of the time the substitution rules apply to those glyph ids 15:41:35 .. Then you have character codes, and depending on location and many other rules, the 15:41:42 .. base glyph can be substituted by something else. 15:41:59 .. For example in Arabic, a positional variant; for Japanese, a variation sequence definition. 15:42:17 .. If you have a ligature for example for a sequence of glyphs, that is applied to the glyph 15:42:22 q+ 15:42:25 .. id sequence mapped from the character codes. 15:42:47 .. You end up as part of this process as one code point entry mapped to a glyph that is 15:42:54 q- 15:42:55 .. one of a number of possibilities. 15:42:58 ack c 15:43:00 ack at 15:43:14 Andreas: A question re GSUB and PUA. Regarding the concerns that Nigel mentioned 15:43:26 .. for example using text for a screen reader, where is the difference between GSUB and 15:43:33 .. the use of PUAs? Both are not very accessible. 15:43:50 Vladimir: It's exactly opposite. Your accessibility is defined by the code point sequence. 15:44:02 .. Then your Unicode sequence does not change and is used by the screen reader. 15:44:15 .. The font level modifications will only affect visible display, not the content itself. 15:44:24 .. That is why this is probably the only accessible way of doing things. 15:44:25 q+ 15:44:47 .. If you move visualisation decisions upstream and simply use a PUA code point to map 15:45:00 .. to a particular glyph, then you break accessibility, because now your screen reader has 15:45:04 .. no idea what that is. 15:45:05 ack at 15:45:19 Andreas: And there is no requirement that the mapping of the glyphs that people will read 15:45:29 .. will go with what is specified by the code points. 15:45:43 Vladimir: Exactly, which is why PUA should be avoided unless there is something that has 15:45:51 .. no meaning for somebody who cannot see the text. 15:46:05 Zapfino example: data:text/html,Zapfino
Zapfin%20o 15:46:16 .. If you have "company name, logo" where logo is a PUA then that's fine if the screen reader 15:46:28 .. ignores the PUA but if the company name is omitted then it will not be accessible. 15:47:05 Nigel: This reminds me of presentation-scheme based fallback options, and I think we 15:47:12 .. should avoid those if we possibly can. 15:47:33 Vladimir: Yes exactly, and that is the basis of the Unicode choice to let font engines 15:47:46 .. do substitutions where needed so that they only affect visual presentation. 15:47:57 Cyril: I asked my font expert if there is a limit to the length of the substitution, and he 15:48:05 .. told me it can be very long, like 30 glyphs. Is there a limit? 15:48:13 Vladimir: I don't think so, only practical limitations. 15:48:27 .. Substitution tables can define a chain of substitutions and it is only limited by 15:48:34 .. complexity and how far a font designer wants to go. 15:48:42 q? 15:49:00 Cyril: Vladimir you were asking for an example. Earlier on IRC I posted a link to one of the 15:49:13 .. requirements that we have. Nigel showed an example of the Twitter logo inline with the 15:49:15 .. text. 15:49:19 Nigel: Thanks for digging that out! 15:49:29 Cyril: It's w3c/tt-reqs#15 15:49:37 Pierre: That's the issue that led to the current situation in IMSC and TTML. 15:49:50 .. It would be good to get input from ARIB with sample text and corresponding render. 15:50:05 Vladimir: Yes, for example if someone wants to define the logo as a PUA code in additoin 15:50:14 .. to the name Twitter, then that would be fine. 15:50:28 .. But if you drop the name and only use the PUA for the logo, it breaks accessibility. 15:50:41 .. Better to do it as a font substitution, for visual presentation. 15:50:52 .. As far as content sequences are concerned the name Twitter is still there. 15:51:06 Cyril: Also graceful degradation, in case the font engine doesn't support substitution. 15:51:19 Vladimir: I agree. Any time substitution fails you see the original unsubstituted text. 15:51:53 .. For company names that's fine. For Devanagari almost everything is a substitution, so 15:51:56 .. the presentation would fail. 15:52:13 Cyril: I'm trying to get back to the ARIB issue and understand what exactly they wanted. 15:52:29 .. They end by saying to consider that PUA is a simple implementation and a clear indication 15:52:36 .. on the use of GSUB would be helpful. 15:52:50 .. On the first point I think we disagree with them. We don't want to recommend it. 15:53:02 Pierre: I can't even conclude that without seeing what they want to do and making sure 15:53:05 .. that we can do it. 15:53:07 q+ 15:53:20 Cyril: I agree that would be useful. I wonder if we should say that PUA is not recommended. 15:53:38 Pierre: Imagine they come back with a PUA example where we can't give a better alternative. 15:53:57 Cyril: You would want to say at this stage we cannot ... 15:54:03 Pierre: I would like to get a solid example. 15:54:10 Cyril: Yes, okay that's good. 15:54:19 Pierre: If they cannot produce an example that also informs us a lot. 15:54:37 Vladimir: 2 final comments. One on what was just discussed. I don't think we can do anything 15:54:49 .. to stop them using PUA codes. If someone decides to use it we cannot prevent it. 15:55:16 .. On the substitution side, trying to define something in the TTML spec, all we can say 15:55:27 .. is we expect font engines to be conformant with the OFF standard. 15:55:41 .. If they support the standard then that's not a concern. 15:55:52 Cyril: I don't think we want to explain how substitution works in general, but maybe 15:56:07 .. an example of how to use substitution to explain how it can be used to produce 15:56:12 .. inline graphics could be useful in TTML. 15:56:29 Vladimir: That would be fine [assuming that the spec is stuck to] 15:56:32 Cyril: I agree. 15:57:28 SUMMARY: TTWG to request ARIB for examples, and consider adding a substitution example to IMSC or TTML. 15:57:40 Nigel: I think I heard no proposals for substantive language about support for particular 15:57:41 .. features. 15:57:54 Cyril: I think Pierre [who left a moment ago] was saying we should wait for examples first. 15:57:59 just an illustration to my previously used example: https://www.myfonts.com/fonts/linotype/zapfino-extra/ 15:58:27 Cyril: The action is to request this from ARIB as part of a general response? 15:58:28 the whole name is substituted with the glyph that represents the font name 15:58:40 Nigel: I would prefer to wait until we have covered the other ARIB issues but if it is going to 15:58:45 .. be many weeks then I would prefer to do it sooner. 15:58:50 Cyril: Yes that makes sense. 15:59:18 data:text/html,Zapfino
Zapfin%20o 16:00:02 Topic: Meeting close 16:00:31 Nigel: Thanks everyone. We're out of time so I'll adjourn now. 16:00:45 .. We didn't manage to get to Pierre's AOB point, so hopefully we can cover that off-line. 16:00:48 .. [adjourns meeting] 16:00:53 rrsagent, make minutes v2 16:00:53 I have made the request to generate https://www.w3.org/2020/05/28-tt-minutes.html nigel 16:05:28 Chair+ Gary 16:07:10 s|s/but|| 16:07:20 s/add something but/add something 16:07:44 s/additoin/addition 16:08:49 rrsagent, make minutes v2 16:08:49 I have made the request to generate https://www.w3.org/2020/05/28-tt-minutes.html nigel 16:15:17 scribeOptions: -final -noEmbedDiagnostics 16:15:21 zakim, end meeting 16:15:21 As of this point the attendees have been Vladimir, Nigel, Atsushi, Pierre, Andreas, Gary, Cyril 16:15:23 RRSAgent, please draft minutes v2 16:15:23 I have made the request to generate https://www.w3.org/2020/05/28-tt-minutes.html Zakim 16:15:26 I am happy to have been of service, nigel; please remember to excuse RRSAgent. Goodbye 16:15:30 Zakim has left #tt 16:15:44 github-bot, end 16:15:44 nigel, Sorry, I don't understand that command. Try 'help'. 16:15:49 github-bot, help 16:15:49 nigel, The commands I understand are: 16:15:49 help - Send this message. 16:15:49 intro - Send a message describing what I do. 16:15:50 status - Send a message with current bot status. 16:15:50 bye - Leave the channel. (You can /invite me back.) 16:15:50 end topic - End the current topic without starting a new one. 16:15:51 reboot - Make me leave the server and exit. If properly configured, I will then update myself and return. 16:15:59 github-bot, status 16:15:59 nigel, This is wgmeeting_github_ircbot version 0.3.8, compiled from b9408f2deaad9c21743302005be9c892f2611f44, which is probably in the repository at https://github.com/dbaron/wgmeeting-github-ircbot/ 16:15:59 I currently have data for the following channels: 16:15:59 #tt (18 lines buffered on "Meeting close") 16:16:00 no GitHub URL to comment on 16:16:06 github-bot, end topic 16:16:10 github-bot, status 16:16:10 nigel, This is wgmeeting_github_ircbot version 0.3.8, compiled from b9408f2deaad9c21743302005be9c892f2611f44, which is probably in the repository at https://github.com/dbaron/wgmeeting-github-ircbot/ 16:16:10 I currently have data for the following channels: 16:16:10 #tt (no topic data buffered) 16:16:25 rrsagent, excuse us 16:16:25 I see no action items