W3C

Timed Text Working Group Teleconference

19 December 2024

Attendees

Present
Andreas, Atsushi, Cyril, Nigel, Pierre
Regrets
Gary
Chair
Nigel
Scribe
nigel

Meeting minutes

This meeting

Nigel: Today we have some DAPT stuff, IMSC 1.3 and Charter.
… And an end of year AOB.
… Anyone for anything else, or points to make sure we get to?

Pierre: IMSC and ARIB

Nigel: That's on the agenda

DAPT

CR publication status

Nigel: I don't believe Atsushi has opened the transition request GitHub issue yet.
… We have a late substantive PR, and there's a publication moratorium I think next week and the week after

Atsushi: I haven't heard from Security WG and will ping Simone for this shortly.

Nigel: I'm hoping we can get this published really soon in January

Atsushi: I believe so. I plan to file the transition request issue , which is already 1.5 months ago
… so I believe we can set a deadline of 0.5 or 1 month from now
… In any case I will ping them - a normal amount of time has already elapsed.

Add an XSD w3c/dapt#273

github: w3c/dapt#273

Cyril: I thought there would be a quick way to run a command line tool to validate
… a document against an XSD.
… I didn't find one.
… Maybe we should document that for people

Nigel: I still feel sure there are command line tools.
… I found a python library called xmlschema and another Java app that wraps native Java
… functionality that should do it.
… It's really easy to write a few lines of python to validate against the schema,
… so one option is to create a validator and put it in the repo, or in a separate repo.
… What's most useful here?

Cyril: If I struggle, others would too. Obviously you can write a wrapper around a library,
… and people might not be confident.
… I agree, if you have a python wrapper it would help people.
… Could be in the same repo, I don't know.

Andreas: Usually a command line utility would work. I'm not sure what's wrong with this schema.

Cyril: I tried xmllint and it didn't work. Saxon EE may have it, but Saxon HE doesn't.

Andreas: Saxon EE definitely, it's well known, but it's not a free tool.
… I can also check. As you say, it's not only an issue for DAPT but all other TTML schemas.
… Pierre, you are also implementing an online schema validator, right?

Pierre: Yes, just the Java one. It's a wrapper.
… Very few command line validators work with more than one XSD.
… If you have dependencies between XSDs it's much harder.
… Online is best, right, because it's easiest for people to run.
… But a command line wrapper that includes all the XSDs and loads them properly is probably easiest for the end user.

Nigel: If it's going to help validate the PR I can add a few lines of Python and install instructions
… into the repo.

Cyril: I support that.

SUMMARY: @nigelmegitt to add a validator script that uses the XSD

Nigel: Any other recommendations for command line validators also very welcome!

Add daptm:descType feature and permit user-defined values w3c/dapt#278

github: w3c/dapt#278

Nigel: This has an approval and has been open for 13 days, so my plan is to merge it tomorrow.
… I wanted to raise it in a call because it's substantive.
… And to give the opportunity for comment.

Cyril: It feels like the Registry definition should state if user defined values should be allowed,
… I mean guidance to registry authors to think about allowing user defined values.

Nigel: We had it in one registry and not in the other.

Cyril: Yes, we just missed it.

Nigel: But this is more than that - we were missing an extension feature for descType,
… so this adds that.
… Once it's merged I'll add it to the implementation report.
… [describes the PR as per the PR description]
… Does anyone need more time for this? If not I'll merge it tomorrow.

no requests for more time

SUMMARY: @nigelmegitt to merge tomorrow if no new requests for change

IMSC 1.3

Pierre: I plan to create an initial draft after the break

Nigel: Great. Do you need any new repos?

Pierre: No I don't think so

Nigel: It's just about creating the document then

Pierre: Yes. Sorry for the delay.
… We're about to run out of time for any ARIB stuff
… so unless there's something concrete in the next couple of weeks its not going to make it.
… The window is closing.

Nigel: We had some communication with ARIB. Are we expecting anything from them?

Atsushi: We can send a liaison and continue with private conversations.
… I suppose it is quite hard for them to make official statements in the timescale.

Pierre: They've had 4 years! It's fine though, if they're not interested.

Atsushi: I will contact them directly in person.
… They need to get stamps from bottom to top for any official response, even if it's the same answer
… that they give unofficially.
… The easiest way is to ask them just in person about any updates and
… after we update our spec and we ask them via an official liaison if it is fine for them then they
… will say yes.

Pierre: I do have a philosophical question:
… So far we have done IMSC incrementally, incrementing version numbers.
… Every time we have added and deprecated features.
… The next version will presumably be 1.3.
… Do we really want that or adopt a different scheme.
… In 1.2 there was one feature in particular added, downloadable fonts.
… I've not seen that used in practice.
… Has it been used?
… If not, should we consider deprecating it or is there a different mechanism
… by which we can communicate to the world that it is not really used.
… 1.2 also did other things like improving the document structure.

Nigel: The need for a specific font is definitely something that the BBC has.
… The mechanism for this depends on the delivery route.
… In the UK there's an IP TV platform called Freely that uses a DASH implementation, and
… BBC signals subtitles in DASH manifests for that, and uses a DVB DASH feature external
… to the TTML document, which tells the player to load a font and associates it with a fontFamily name.
… So our subtitles come out in our font.

Pierre: The IMF (Interoperable Master Format) also does this.

Andreas: And DVB TTML has a mechanism too.

Pierre: Of all the features that's not one that's been requested.

Nigel: My philosophical reason for being a bit keen at least to keep it is:
… what if an IMSC document is referenced directly in a web page, that might have some kind of
… polyfill or whatever for playing IMSC documents? Without the feature, there's no other
… way to signal the need for a font.

Pierre: I don't disagree, but we're far from having native playback of TTML in pages.
… The question on my mind is do we want to carry around something that's aspirational, or not?
… There are pluses and minuses. The minus is that it's not great to have an unimplemented feature.
… It's a way to have bugs that we don't know, and a source for spec errors.
… There are tons of things in HTML and CSS that are in the spec and partially implemented.
… So we could go down that path.

Andreas: I'm hesitant on that feature because it's not an exotic one.
… The use case seems to be not very far away from what could be needed in operation.
… If it's really an issue to carry this feature around we should ask the community, rather than
… jumpting to deprecation.

Nigel: We should think about path to deprecation, and the community.
… The cost of retaining a feature already in a Rec is minimal.

Pierre: The cost could be in user surprise though, if document authors use it and find it doesn't work.
… It's only one feature among so many.
… It sounds like for the first draft at least it will stay in, and we can think about it.

Nigel: It's absolutely worth raising.

Pierre: The challenge more widely is around interop.
… Thanks for that, I appreciate the input.
… I will create a set of PRs, one for every issue, and send them for review.

Nigel: What will you raise them against?

Pierre: The head of the repo is 1.2, as soon as we merge one then it will become a 1.3 ED.

Nigel: In terms of timing, January should be fine.
… Otherwise getting it in the new Charter could be awkward

Pierre: It should be possible to merge at least one so we have a draft to point to.

Charter 2025

Nigel: My draft charter PR has had approvals from everyone who needs to.
… Atsushi, do you want me to merge it?

Atsushi: You can merge it.
… From now I need to issue advance notice to AC and update it in line with the Charter Template
… and request Horizontal Review which takes maybe 1 month.
… After that I don't think we will receive any comments but we may update minor things.
… Then I will request a 1 month AC review period.
… I will raise another pull request for the charter template changes.
… Also if anyone in the WG or anyone from participating organisations in TTWG has any comments
… on the current Charter please provide them as soon as possible.
… Before bringing it to AC!

<atsushi> check at htmlpreview

AOB - Thanks for all your work in 2024!

Nigel: Thanks for all your hard work this year everyone, a small number of us doing a lot.
… Have a good break if you're getting one.

Pierre: Warmest wishes for the holidays and the new year

Andreas: All the best from me for the new year - have a nice time

Cyril: Likewise!

Nigel: The next call will be 16th January. I cancelled the 2nd Jan one due to availability.
… Let's adjourn for today and for 2024. See you next year! [adjourns meeting]

Minutes manually created (not a transcript), formatted by scribe.perl version 240 (Tue Dec 10 03:59:59 2024 UTC).