IRC log of tt on 2023-09-28

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Meeting: Timed Text Working Group Teleconference
15:01:21 [nigel]
Agenda: https://github.com/w3c/ttwg/issues/263
15:01:59 [nigel]
Previous meeting: https://www.w3.org/2023/09/12-tt-minutes.html
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15:03:05 [nigel]
scribe: nigel
15:03:13 [nigel]
Present: Nigel, Gary, Cyril, Pierre
15:03:20 [nigel]
Regrets: Andreas
15:03:37 [nigel]
Topic: This meeting
15:03:43 [nigel]
Nigel: Today our agenda is:
15:03:55 [nigel]
.. TPAC 2023 reflections
15:04:37 [nigel]
.. IMSC-HRM - do we have anything to cover on this today?
15:04:37 [nigel]
Pierre: We received feedback from one content provider, which was positive.
15:04:46 [nigel]
.. I am working with three others.
15:05:00 [nigel]
.. So far, it's been pretty good.
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.. Bugs were found in the reference implementation, which were fixed.
15:05:19 [nigel]
.. There are also bugs in some content providers' libraries.
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.. I'm cautiously optimistic that there are no major issues with the spec itself.
15:05:40 [nigel]
.. Now everybody is back from IBC and vacation I'm going to try to get it done by end of October.
15:05:49 [nigel]
Cyril: You said one provider - that's Netflix, right?
15:05:58 [nigel]
Pierre: Yes, the only one who has provided feedback to the group.
15:06:07 [nigel]
.. One of the three others has provided me with some results privately.
15:06:33 [nigel]
Cyril: I don't know what we decided - when we did the test Nigel there were bugs, but that's okay.
15:06:45 [nigel]
.. The Netflix content did not invalidate the IMSC-HRM model, so it is probably good.
15:06:57 [nigel]
.. One thing we found that was interesting, but still does not jeopardise the model,
15:07:21 [nigel]
.. for some content, Netflix produces content with very small cues - I ran about 3000 pieces of content -
15:07:30 [nigel]
.. and we decided the content should have been authored differently.
15:07:41 [nigel]
.. The issue is with 2 speakers speaking almost at the same time, they have cues that overlap,
15:07:47 [nigel]
.. but not completely, in time.
15:08:00 [nigel]
.. If you have 2 speakers, one speaks, then the other starts speaking, then the first stops,
15:08:19 [nigel]
.. Netflix splits that into 3 non-overlapping ISDs. If they are very short, that was creating a
15:08:25 [nigel]
.. content validation error according to the HRM.
15:08:33 [nigel]
.. I suggest we keep that as an issue and keep talking about it.
15:08:38 [nigel]
Pierre: Yes, I think that's worth discussing.
15:09:00 [nigel]
.. The bottom line is that the HRM model does not assume that the renderer can detect identical
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.. regions or parts of ISDs.
15:09:25 [nigel]
Nigel: It does assume some level of caching, at least.
15:09:41 [nigel]
Pierre: Yes but it has no notion of identical content, so background redraws are not cached, for example.
15:09:45 [nigel]
.. I'm not sure it's a problem.
15:10:02 [nigel]
.. The Netflix approach, which Cyril will raise as an issue, was introduced to work around some
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.. limitations of some clients.
15:10:30 [nigel]
Nigel: I think we just completed that agenda topic!
15:10:55 [nigel]
i/Pierre: We received/Subtopic: IMSC-HRM review feedback
15:11:03 [nigel]
Subtopic: Agenda continued
15:11:16 [nigel]
Nigel: We may also have a few things to discuss on DAPT.
15:11:33 [nigel]
.. In AOB, Andreas sent an email reminder about the DVB liaison, and I have responded
15:11:45 [nigel]
.. on the member-tt list. Not sure if we have anything more to discuss during this call?
15:12:13 [nigel]
group: no request to discuss further today
15:12:26 [nigel]
Nigel: Is there any other business, or points to make sure we cover?
15:13:09 [nigel]
Pierre: What's the plan wrt that liaison?
15:13:22 [nigel]
Nigel: Let's cover in TPAC 2023 reflections
15:13:40 [nigel]
Present+ Atsushi
15:13:47 [nigel]
Topic: TPAC 2023 reflections
15:13:59 [nigel]
Nigel: Just want to open up to any thoughts or observations anyone had?
15:14:18 [nigel]
.. I should comment about the joint meeting with APA WG and MEIG on the Thursday afternoon.
15:14:52 [nigel]
.. We had a good discussion, and it included the liaison from DVB, which APA WG was interested in also.
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.. Since the liaison wasn't clearly targeted at any one group, but several might be interested,
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.. I asked for a single team contact to bring together the responses and look after sending them.
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.. François (tidoust) offered to do this or identify someone else who would.
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.. In that context I think we should bring him in on the reflector discussions.
15:16:52 [nigel]
.. Does anyone have any comments on the response draft from Andreas and my reply?
15:17:01 [nigel]
Pierre: Yes, sounds like a good idea to refresh our collective memory.
15:17:27 [nigel]
-> https://lists.w3.org/Archives/Member/member-tt/2023Sep/0002.html DVB Liaison (member only reflector link)
15:20:40 [nigel]
Nigel: [iterates through the liaison input]
15:22:03 [nigel]
Pierre: On the point of audio track language, and the interaction between the audio signalled in the
15:22:19 [nigel]
.. content and user preference, I think any metadata document that describes what to signal in the content
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.. is not useful unless there's an algorithm indicating how that metadata is used by the client.
15:22:43 [nigel]
.. There are subtle interactions between choice of language on the client, whether or not the client
15:23:01 [nigel]
.. has indicated it would like captions or subtitles, and there have been attempts at doing that.
15:23:07 [nigel]
.. it's a surprisingly really hard problem.
15:23:23 [nigel]
.. It would be great to standardise something, and the algorithm should be standardised to, for the client.
15:23:41 [nigel]
Nigel: I would like to say that too.
15:23:56 [nigel]
Pierre: We should say it plainly: unless there's an algorithm that specifies the interaction between
15:24:04 [nigel]
.. user choices and signalling then it is incomplete work.
15:24:21 [nigel]
.. There was an algorithm created back in the Ultraviolet/DECE days, and it's quite complex.
15:24:29 [nigel]
Nigel: Yes, I tried reading that once!
15:24:33 [nigel]
Pierre: We should really emphasise that point.
15:24:41 [nigel]
.. It's particularly important when forced narrative is available.
15:24:43 [nigel]
Nigel: Yes
15:25:09 [nigel]
.. Any more on that, or on TPAC more generally?
15:25:24 [nigel]
Pierre: On TPAC more generally, I was there for the discussion about Apple's suggestion on an API
15:25:40 [nigel]
.. for improving TextTrackCue. Do you know if this is going to be turned into an effort within this
15:25:44 [nigel]
.. group or another group?
15:26:13 [nigel]
Gary: I think it's on Apple to take the action of updating all the relevant specs like HTML, WebVTT etc
15:26:52 [nigel]
-> https://github.com/whatwg/html/pull/9771 WHATWG pull request on HTML
15:27:06 [nigel]
Nigel: They have opened the above pull request on HTML.
15:27:36 [nigel]
.. There's a lot of HTML spec complexity in there, but in terms of the basic requirements I have
15:27:47 [nigel]
.. added a couple of comments, and recommend others review too.
15:29:32 [nigel]
Nigel: The issue I have with this now is that without full CSS support for fillLineGap and linePadding I don't know how we could use it.
15:29:56 [nigel]
Pierre: In creating imscJS we spent a lot of time working out how to make it match the TTML expectations.
15:30:08 [nigel]
.. I'm not aware of any effort being done to validate this API, is my summary.
15:30:22 [nigel]
Gary: From my understanding, the API doesn't preclude any of that, the only change in IMSC is to add
15:30:41 [nigel]
.. the attribute tags to the output HTML from imscJS, so the styling should just be carried over.
15:30:55 [nigel]
Pierre: I can believe that theoretically, but we need to see a comparison between the rendered output and
15:31:00 [nigel]
.. the test references.
15:31:09 [nigel]
Gary: I guess that's part of getting the pull request approved.
15:31:20 [nigel]
Pierre: The reason I'm raising it is that HTML and CSS and TTML are each complex.
15:31:27 [nigel]
.. I've surprised myself in the past with corner cases.
15:31:44 [nigel]
Gary: They brought up that there can be conflicts between the user setting overrides and the
15:32:09 [nigel]
.. IMSC presentation. That's another issue - they said there's nothing they can do about that.
15:32:29 [nigel]
Nigel: Two things. Firstly, without CSS support for fillLineGap and linePadding, I think it will be impossible
15:32:46 [nigel]
.. to make the tests all render correctly, because the imscJS code that works around those HTML and CSS
15:32:59 [nigel]
.. limitations cannot run without the HTML fragment being homed to some DOM element.
15:33:15 [nigel]
.. And in the proposal, no client code can run on it when that is the case.
15:33:35 [nigel]
.. Secondly, if CSS support were added for those features, then that could work around some of the
15:34:01 [nigel]
.. oddities that could result from user settings being unexpected, in respect of those two styling features.
15:34:22 [nigel]
.. I haven't even thought about ruby and text decoration but I think that ought to work, in principle.
15:34:37 [nigel]
.. So maybe the feedback to Apple is yes, but we need CSS support for those missing features.
15:34:52 [nigel]
Gary: Yes, and I think that was discussed and maybe we need to bring that in more strongly that as
15:34:59 [nigel]
.. part of this the CSS related discussions need to be restarted.
15:35:13 [nigel]
.. To the first point, potentially, and I guess this is the question, the document fragment we give to the API,
15:35:30 [nigel]
.. there's nothing disallowing it from being added to the DOM first to apply the workaround beforehand.
15:35:54 [nigel]
.. Theoretically this could be done, as a workaround.
15:36:22 [nigel]
Nigel: Yes, though if the user makes the text size bigger then it would break.
15:36:43 [nigel]
Pierre: I don't think anyone has implemented imscJS this way and tested it fully.
15:37:00 [nigel]
Gary: I think Eric did implement it this way, but maybe did not cover all the edge cases.
15:37:14 [nigel]
Pierre: This API is definitely a bit different from what I saw 4 or 5 years ago.
15:37:26 [nigel]
Gary: I don't disagree that a lot more testing is needed, especially with more complex inputs.
15:37:59 [nigel]
Nigel: Sounds like an action to land this point somehow, not sure who is best placed to do so.
15:38:28 [nigel]
.. I'm certainly happy to send a message to Eric and James from Apple, as well as Marcos.
15:39:16 [nigel]
Gary: Final point: they link to some tests they wrote for WebKit in their PR, but it does seem to be on the simple side.
15:39:54 [nigel]
Nigel: Any other TPAC discussion points?
15:39:58 [nigel]
group: none
15:40:08 [nigel]
Topic: DAPT
15:40:15 [nigel]
s/DAPT/IMSC-HRM
15:40:22 [nigel]
Cyril: What are the next steps to move forward?
15:40:29 [nigel]
.. One more content provider reporting and that is it?
15:41:00 [nigel]
Nigel: Good question - what are the exit criteria?
15:41:03 [nigel]
.. We have tests
15:41:06 [nigel]
Pierre: Yes.
15:41:13 [nigel]
.. I think we need 2 content providers. We have one.
15:41:24 [nigel]
.. I'm hoping that we can, in a month, decide whether or not we need changes.
15:41:57 [nigel]
Nigel: [reads CR exit criteria]
15:42:07 [nigel]
Cyril: So we already meet the criteria?
15:42:17 [nigel]
Nigel: Apparently so, though in the weakest way we possibly could!
15:42:35 [nigel]
Atsushi: I'm not sure what the first criteria means - do we need a content document
15:42:49 [nigel]
.. produced by a content producing implementation and validated by a content validator,
15:43:22 [nigel]
.. but I am not sure. We have a manual set of test suites and validated by [scribe missed]
15:43:37 [nigel]
.. but if current criteria are that the same document needs to be produced by one implementation
15:44:00 [nigel]
.. and validated separately, then we need some other set of content.
15:44:18 [nigel]
Nigel: We discussed at the top of the meeting, and mentioned that Netflix has an implementation
15:44:40 [nigel]
.. that they have verified by processing about 3,300 documents through the validator.
15:44:45 [nigel]
Atsushi: That's great!
15:45:01 [nigel]
Cyril: I did send an email. There were ~20 languages, some subtitles for deaf and hard of hearing,
15:45:16 [nigel]
.. some forced narratives, some translation subtitles.
15:45:45 [nigel]
Pierre: As another data point:
15:45:59 [pal]
From another content platform: I ran the tool over the weekend on 25,000 randomly selected samples from our library. I recorded 100 failures and I have attached the output of the tool for those failures.
15:46:11 [nigel]
Pierre: I'm trying to get them to release those results.
15:46:24 [nigel]
.. So far I think all the failures are in the files themselves. That gives a sense of the scale.
15:46:30 [nigel]
.. 25,000 TTML files.
15:46:47 [nigel]
.. So far all the failures were errors in the TTML that probably came from errors in translation from 608,
15:46:53 [nigel]
.. by my guess.
15:47:01 [nigel]
Nigel: Syntactical errors, or something like that?
15:47:23 [nigel]
Pierre: Not sure what you'd call them - for example, timestamps in hh:mm:ss:ff and the frame counter
15:47:37 [nigel]
.. goes beyond the frame rate, e.g. if 30fps, and a frame count of 30!
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RRSAgent, pointer
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See https://www.w3.org/2023/09/28-tt-irc#T15-48-05
15:48:37 [nigel]
Nigel: Occasionally we see errors like that too, which we do catch.
15:48:57 [nigel]
Pierre: We are trying to complete the CR exit criteria report by the end of October.
15:49:35 [nigel]
Nigel: Yes, good idea, let's try to get this completed soon - does that timescale work for everyone?
15:50:02 [nigel]
.. I'm going to record assent by silence here!
15:50:19 [nigel]
.. That's great, gives us about a month to verify that we have met the exit criteria.
15:51:02 [nigel]
Topic: DAPT
15:52:34 [nigel]
Nigel: I have one question - anything from you Cyril?
15:52:40 [nigel]
Cyril: Wide review inputs
15:53:04 [nigel]
Nigel: Yes, I have been making the point generally, on email and to people at IBC, that now is the time
15:53:19 [nigel]
.. to review the spec and provide comments, while we're in WD and more easily can make changes.
15:53:56 [nigel]
.. I did talk to 3 or 4 organisations about DAPT specifically and some were very positive, and said they
15:54:03 [nigel]
.. would either be implementing or reviewing or both.
15:54:10 [nigel]
.. It was extremely positive.
15:54:42 [nigel]
Cyril: I did open the TAG review and the i18n review, since we last talked.
15:54:51 [nigel]
.. I haven't received any feedback yet, though it has not been long.
15:55:04 [nigel]
Atsushi: For i18n we just reviewed it and resolved it as completed, for information.
15:55:13 [nigel]
.. We will mark it as completed shortly.
15:55:15 [nigel]
Cyril: Great!
15:55:26 [nigel]
Atsushi: The action on GitHub might take a little time.
15:55:42 [nigel]
Cyril: I can see that aphilips moved it from in-review to completed an hour ago.
15:56:35 [nigel]
Nigel: One question from me: I thought we had resolved to make langSrc be absent or a language code,
15:56:40 [nigel]
.. but couldn't find it documented.
15:56:42 [nigel]
Cyril: Yes we did
15:56:47 [nigel]
Atsushi: It's in our minutes
15:56:54 [nigel]
Gary: You're not misremembering.
15:57:09 [nigel]
Nigel: Thank you! I think the action is on me to implement that, so I will go ahead with that.
15:57:39 [nigel]
.. The other thing I wanted to note was that I just opened an editorial pull request in response to an
15:57:59 [nigel]
.. issue raised by Andreas, about the definitions of script and transcript, so if anyone can review that,
15:58:06 [nigel]
.. it's only small, and that'd be helpful!
15:58:08 [atsushi]
https://www.w3.org/2023/09/12-tt-minutes.html#x959 ?
15:58:29 [nigel]
-> https://github.com/w3c/dapt/pull/183 Redraft opening section of §2.1 w3c/dapt#183
15:59:24 [nigel]
Cyril: Did you have any feedback from privacy and security reviews?
15:59:27 [nigel]
Nigel: No not yet
15:59:33 [nigel]
Cyril: We discussed removing styles too?
16:00:28 [nigel]
Nigel: Yes we agreed to do that, in w3c/dapt#124
16:01:04 [nigel]
Cyril: The language one was w3c/dapt#148
16:01:09 [nigel]
Nigel: Ah, thank you, I will do that.
16:01:14 [nigel]
Topic: Meeting close
16:01:30 [nigel]
Nigel: Thank you everyone, we're at time, and just completed the agenda. Let's adjourn. Be free!
16:01:37 [nigel]
.. [adjourns meeting]
16:01:38 [nigel]
rrsagent, make minutes
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I have made the request to generate https://www.w3.org/2023/09/28-tt-minutes.html nigel
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Chair: Gary, Nigel
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s|reads CR exit criteria|reads CR exit criteria at https://www.w3.org/TR/imsc-hrm/#sotd
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s/Occasionally we see errors like that too/Occasionally we see errors like that too in our tooling in the BBC
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rrsagent, make minutes
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I have made the request to generate https://www.w3.org/2023/09/28-tt-minutes.html nigel
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scribeOptions: -final -noEmbedDiagnostics
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zakim, end meeting
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As of this point the attendees have been Nigel, Gary, Cyril, Pierre, Atsushi
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RRSAgent, please draft minutes v2
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I have made the request to generate https://www.w3.org/2023/09/28-tt-minutes.html Zakim
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I am happy to have been of service, nigel; please remember to excuse RRSAgent. Goodbye
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rrsagent, excuse us
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I see no action items