15:58:00 RRSAgent has joined #tt 15:58:04 logging to https://www.w3.org/2025/01/30-tt-irc 15:58:04 RRSAgent, make logs Public 15:58:05 Meeting: Timed Text Working Group Teleconference 15:58:17 agenda: https://github.com/w3c/ttwg/issues/299 15:58:19 scribe: nigel 15:58:24 Chair: Nigel 15:58:30 Regrets: Gary 15:58:33 Present: Nigel 15:58:43 Previous meeting: https://www.w3.org/2025/01/16-tt-minutes.html 16:02:08 Present+ Andreas, Atsushi, Pierre 16:04:56 Present+ Cyril 16:05:18 Topic: This meeting 16:05:41 Nigel: Today we have some DAPT, some IMSC items. 16:05:54 .. Any other business, or points to make sure we get to within those topics? 16:06:59 no other business 16:07:00 atai has joined #tt 16:07:12 Topic: DAPT 16:07:37 Nigel: Regarding CR publication there has been some movement in getting the Security review completed. 16:08:04 -> https://github.com/w3c/security-request/issues/59 Security review for DAPT 16:08:34 .. There has been some discussion, even up to 5 minutes ago 16:09:50 .. It seems there is a conversation happening, which I hope we can conclude soon. 16:11:01 .. For example there is a question about whether there is provision for data integrity so that 16:11:13 .. it can be determined whether a file has been modified on the way to the processor. 16:11:18 .. My response would be that is out of scope. 16:11:27 Cyril: I agree. You can do an MD5 or whatever. 16:11:37 Nigel: It should not be part of the file specification itself. 16:12:39 .. He also answers the question about metadata manipulation. 16:12:47 Cyril: It's interesting, we have a good threat model now. 16:12:56 .. It's nothing on top of TTML2. 16:13:05 .. What do we need to do to call the security review done? 16:13:14 .. Do we need them to tell us it's ok or something needs changing? 16:13:26 Atsushi: Usually yes for everything to be okay. 16:13:58 .. This should be first of all not such a common review request for a data format. 16:14:12 .. Mostly the discussion is focused on data handling and browsers. 16:14:26 .. I suppose there might be some need for teaching them about our fundamentals. 16:14:46 .. At this point I can't say what comment or background information we should provide. 16:15:14 Nigel: I sense that we should continue the thread until all questions have been answered, 16:15:32 .. and then check back in with the reviewer to confirm he's happy for us to proceed. 16:15:51 .. I am expecting some kind of yes/no from the reviewer though. 16:16:28 Cyril: I agree, continue the conversation and then ask him if we need to change the spec or if we are good to go, 16:16:35 .. and then take on his response. 16:17:03 Nigel: I agree 16:17:10 .. Any other points about the reviews or moving to CR? 16:17:25 Cyril: Not about that, but last time we talked about producing test vectors. 16:17:33 .. We should maybe do a session and produce them. 16:17:35 Nigel: Yes 16:17:41 Cyril: Let's coordinate offline Nigel 16:17:48 Nigel: Yes let's do that. 16:18:16 .. We have an Implementation Report but there's nothing to add - no change since last meeting. 16:18:32 Cyril: We said we wanted to add at-risk features. 16:18:41 Nigel: Yes we did, I haven't got around to doing it. 16:19:27 .. I have an AOB I will raise about DAPT. 16:19:42 Topic: IMSC 1.3 16:20:01 Nigel: The only thing on the agenda is the Update namespace documents ticket 16:20:24 Subtopic: Update namespace documents w3c/imsc#589 16:20:26 github: https://github.com/w3c/imsc/pull/589 16:21:19 Nigel: I think we're waiting on Atsushi for how to update namespace documents 16:21:28 Atsushi: I'm still getting up to speed on this. 16:21:42 .. I think I will open a PR onto the W3C repo directly and see what will happen 16:21:48 Pierre: Sounds like a good idea 16:22:06 Atsushi: I'm not sure what kind of DTD or supporting material we should attach to it. 16:22:45 .. I suppose nobody in industry will expect material or DTDs from the namespace URLs, right? 16:23:04 .. I had several identity-related libraries getting DTDs from namespace URLs 16:23:18 .. but for our case in TT we just use them to define a namespace. 16:23:26 .. I'm not familiar with the tools for implementations. 16:23:41 Pierre: I think that the requirement is that every time a namespace is created in a document 16:23:54 .. that it be formally reserved, set aside, and the way to do that is by publishing a namespace document. 16:24:21 .. Even though the chance of namespace reuse is very low, I understand this is a formal requirement of W3C. 16:24:35 Atsushi: If implementations will not look at the contents of the URL, we may 16:25:05 .. not need to pay strict attention to its content. 16:25:22 Pierre: There's no DTD here, or XSL or anything like that. It's just a web page. 16:25:27 Atsushi: Then let me go and try and see what happens. 16:25:44 SUMMARY: @himorin to open a pull request to add the new namespace pages 16:27:08 Subtopic: Add support for subscripts and superscripts w3c/imsc#585 16:27:16 github: https://github.com/w3c/imsc/pull/585 16:30:11 Nigel: [summarises https://github.com/w3c/imsc/pull/585#pullrequestreview-2536922277] 16:30:19 .. So the two main questions are: 16:30:34 .. 1. Do we need to fix up TTML2 before referring to fontVariant? 16:30:56 .. 2. How much do we care about what the UA actually does if it doesn't fully support this? 16:31:29 .. Or if the font doesn't fully support superscript and subscript for every glyph in the super or subscript text. 16:31:57 Pierre: Overall I think this is a feature in flux in CSS, it changed even in the past couple of months. 16:32:02 .. The semantic intent is pretty clear though. 16:32:15 .. The fallback is very specific today, to HTML and CSS as currently implemented. 16:32:29 .. My conclusion is not changed, that for the purpose of TTML and IMSC we can use fontVariant 16:32:44 .. and things like imscJS will probably implement the fallback, but it's an implementation detail that 16:32:47 .. might change in 2 months. 16:33:03 .. Separately we can improve TTML2, but it's a separate issue. 16:33:27 Nigel: OK, second question: what is the range of acceptable behaviour for the UA? 16:33:58 Pierre: Looking at the current text... 16:34:07 -> CSS Fonts Level 4 Subscript and superscript forms https://drafts.csswg.org/css-fonts/#font-variant-position-prop 16:34:48 Pierre: [reads text from CSS spec] 16:34:54 .. I think the intent is super clear 16:35:06 .. The dispute in the browser world is not the semantics, but about whether or not the UA 16:35:16 .. is expected to synthesise the font variant if it doesn't exist. 16:35:45 Nigel: OK, but there is no link through via TTML2 to this CSS spec text. 16:35:53 Pierre: You mean because the link is broken? 16:36:04 Nigel: Yes, but even if it weren't broken, it's informative and the TTML2 16:36:14 .. text on tts:fontVariant has a lot less information in it. 16:36:42 -> TTML2 tts:fontVariant specification https://www.w3.org/TR/ttml2/#style-attribute-fontVariant 16:37:16 .. It doesn't hint about synthesis or fallback 16:37:22 Pierre: There's a semantic basis in the table 16:37:37 Nigel: That's what's broken! 16:37:51 Pierre: I can raise a PR to fix the semantic basis link to CSS. 16:37:58 .. It links to CSS Fonts Level 3... 16:38:38 Nigel: It's missing from there 16:38:42 Pierre: No, it's in there. 16:38:54 Nigel: Did I make a mistake? Oh, it's just the section number that changed. 16:39:18 -> CSS Fonts Level 3 ยง6.5 Subscript and superscript forms https://www.w3.org/TR/2018/REC-css-fonts-3-20180920/#font-variant-position-prop 16:39:57 Nigel: Clearly they want to make some tweaks in Level 4 but this is fine. 16:40:27 .. TTML2 doesn't even hint at anything except for use of the OpenType features, 16:40:33 .. but CSS certainly does. 16:41:06 .. I'd be a lot happier if either TTML2 or IMSC said something about fallback alternatives, either way. 16:42:01 .. Basically, is it ok if a UA doesn't do anything when the sub or super variants are absent from the font? 16:42:21 Pierre: I think it's explicit on what it should look like, the fallback is an implementation detail I think. 16:42:40 Nigel: I could read it a different way, which is that the implementation should simply select the 16:43:02 .. variant glyphs using the OpenType feature, and if they're absent, there's no behaviour specified. 16:43:06 .. In other words, anything is ok. 16:43:24 Pierre: I think that's the point of contention in the browser community, last time I checked. 16:43:34 Nigel: OK, so what do we do? 16:43:47 Pierre: I think we should be happy with the semantic basis definition, and the syntax. 16:44:00 .. I don't think anyone disputes what superscript and subscript mean 16:44:14 .. I'd consider correcting the section reference in TTML2, but otherwise leave it as is. 16:44:24 .. If CSS settles in a couple of months maybe we'll have a reason to revise it. 16:44:51 Nigel: I think that's a good starting point, and like you say there's time for us to keep watching and thinking. 16:45:00 Pierre: I will have to pay attention to it. 16:46:57 Nigel: [hunts for CSS issues] 16:47:07 .. Too many to trawl through right now. 16:47:51 SUMMARY: Update the semantic basis reference in TTML2, keep watching for CSS updates on this feature 16:49:08 Nigel: It's w3c/ttml2#1277 16:49:15 Pierre: I'll prepare a pull request for that. 16:49:44 .. Any comments on the IMSC pull request? 16:49:49 Nigel: No, the text is super simple 16:49:59 Pierre: If you can approve it then I'll fix up TTML2 16:50:00 Nigel: OK 16:50:02 Pierre: Super 16:50:40 Topic: AOB - Assembling timed transcript of e.g. DAPT 16:51:13 Nigel: Use case is, you have a TTML document that describes how new words get added over time. 16:51:25 .. But then you want to present that in a non-TTML sort of view, 16:51:43 .. As a complete document, where you do something like highlighting active text at a particular time 16:51:49 .. during playback of related media. 16:51:55 .. Like a transcript view. 16:52:27 .. But then the source TTML might have content in different ISDs put into different `

` elements 16:52:36 .. even if that text is all part of the same sentence, for example. 16:52:55 .. Then when you assemble those `

` elements together the semantic connection between them 16:53:09 .. doesn't exist and you get weird paragraph breaks in the middle of sentences. 16:53:31 .. Really a problem for DAPT because of the timing structure we have defined. 16:54:35 .. I wonder if, maybe not in v1, we need to add markup to allow transformation processors to 16:54:49 .. understand that different block elements actually contain related text, e.g. part of the same sentence 16:54:58 .. spoken by the same person. 16:55:13 .. Has anyone else encountered this or developed any solutions? 16:55:51 cyril has joined #tt 16:55:55 RRSAgent, pointer 16:55:55 See https://www.w3.org/2025/01/30-tt-irc#T16-55-55 16:56:00 rrsagent, make minutes 16:56:01 I have made the request to generate https://www.w3.org/2025/01/30-tt-minutes.html nigel 16:56:36 Cyril: Like transcripts alongside videos that highlight the currently spoken text - like that? 16:56:40 Nigel: Yes, that sort of thing. 16:57:33 Cyril: What sort of relationship do you want to represent? 16:57:43 Nigel: Continuations really, where you don't want a line break. 16:57:53 Cyril: Could you use timing-based heuristics? 16:58:09 Nigel: Sometimes people leave gaps during sentences but you don't want a line break. 16:58:52 Cyril: It's subjective - I agree you would need to capture the author's intent. 16:59:02 Andreas: You are targeting a presentation out of scope of TTML, right? 16:59:13 .. You are looking for something that would be a different presentation form. 16:59:17 Nigel: Strictly, yes. 16:59:33 Andreas: So you would want to add some metadata to give the flexibility to make it possible? 16:59:38 Nigel: I think so, yes. 17:00:01 Andreas: I can only think that metadata to relate TTML content together, unrelated to TTML layout, 17:00:21 .. that you could use for whatever you want, could help. Some semantic unit ID or whatever, so you can make sense of it. 17:00:35 Nigel: Yes that's the sort of direction I was heading in. 17:01:28 .. Thanks, that was a useful discussion. 17:01:31 Topic: Meeting close 17:01:47 Nigel: Thanks everyone, we're at time so let's finish. 17:01:57 .. [adjourns meeting] 17:02:00 rrsagent, make minutes 17:02:01 I have made the request to generate https://www.w3.org/2025/01/30-tt-minutes.html nigel 17:06:50 s/confirm he's happy/confirm they're happy 17:07:06 s/and then ask him/and then ask them 17:07:22 s/take on his response/take on their response 17:10:15 s/.. It doesn't hint/Nigel: It doesn't hint 17:12:24 rrsagent, make minutes 17:12:25 I have made the request to generate https://www.w3.org/2025/01/30-tt-minutes.html nigel 17:13:10 scribeOptions: -final -noEmbedDiagnostics 17:13:14 zakim, end meeting 17:13:14 As of this point the attendees have been Nigel, Andreas, Atsushi, Pierre, Cyril 17:13:16 RRSAgent, please draft minutes v2 17:13:17 I have made the request to generate https://www.w3.org/2025/01/30-tt-minutes.html Zakim 17:13:24 I am happy to have been of service, nigel; please remember to excuse RRSAgent. Goodbye 17:13:24 Zakim has left #tt 17:13:59 rrsagent, excuse us 17:13:59 I see no action items