{Minutes} TTWG Teleconference 2025-09-25

Thanks all for attending today’s TTWG meeting. Minutes can be found in HTML format at https://www.w3.org/2025/09/25-tt-minutes.html


In plain text:

   [1]W3C

      [1] https://www.w3.org/


                Timed Text Working Group Teleconference

25 September 2025

   [2]Previous meeting. [3]Agenda. [4]IRC log.

      [2] https://www.w3.org/2025/09/11-tt-minutes.html

      [3] https://github.com/w3c/ttwg/issues/316

      [4] https://www.w3.org/2025/09/25-tt-irc


Attendees

   Present
          Andreas, Atsushi, Chris_Needham, Cyril, Gary, Nigel,
          Pierre

   Regrets
          -

   Chair
          Gary, Nigel

   Scribe
          cpn, nigel

Contents

    1. [5]This meeting
         1. [6]Make the reference to The Unicode Standard undated
            w3c/imsc#618
         2. [7]Improve the ja character set per ARIB feedback
            w3c/imsc#614
         3. [8]Wide Review
         4. [9]Response to ARIB
    2. [10]DAPT
         1. [11]Use zxx in place of an empty daptm:langSrc
            w3c/dapt#322
    3. [12]WebVTT open issues
    4. [13]TPAC 2025 planning
    5. [14]Meeting close

Meeting minutes

  This meeting

   Nigel: [Recaps the agenda]
   … Anything else to cover, or points on the agenda items?

   (nothing)

   Topic IMSC

    Make the reference to The Unicode Standard undated [15]w3c/imsc#618

     [15] https://github.com/w3c/imsc/issues/618


   github: [16]w3c/imsc#618

     [16] https://github.com/w3c/imsc/pull/618


   Pierre: The ISO platform doesn't offer URLs to the latest
   edition of the standard

   Gary: Unless we want to refer to Unicode instead?

   Nigel: Why not refer to Unicode?

   Pierre: Other specs refer to it
   … ARIB refers to collections, and I want to make sure that's in
   the Unicode standard, not only in ISO

   Nigel: I checked the ISO website, they have a mechanism for
   adding dated and undated links to ISO specs, but I couldn't
   find access to the database they use

   Pierre: Could change the reference from ISO 10646 to Unicode
   and be done
   … It's free to download from ISO

   Nigel: To answer this, there should be precedent from elsewhere
   in W3C

   Pierre: What about TTML2?
   … That references the Unicode spec
   … The ISO reference came up in response to ARIB, but everywhere
   else we reference Unicode

   Gary: CSS Selectors links to Unicode. The two are functionally
   equivalent

   Pierre: I'll just reference Unicode

   Gary: Sounds good

   Nigel: Sounds good

   SUMMARY: Change 10646 reference to Unicode

    Improve the ja character set per ARIB feedback [17]w3c/imsc#614

     [17] https://github.com/w3c/imsc/issues/614


   github: [18]w3c/imsc#614

     [18] https://github.com/w3c/imsc/pull/614


   Pierre: Atsushi, if I accept both your comments, are you happy
   with the PR?

   Atsushi: The comment about ARIB was just a suggestion

   [19]Atsushi's comment

     [19] https://github.com/w3c/imsc/pull/614#issuecomment-3332729041


   Atsushi: The comment relates to the suggested change above.

   Pierre: I accepted the suggestion. Is the PR ok now?

   Atsushi: Yes

   SUMMARY: Atsushi's comments accepted

    Wide Review

   Pierre: I think we're done with wide review. There's a
   potential editorial note by APA

   <atsushi> [20]wide review tracker

     [20] https://github.com/w3c/imsc/issues/608


   Nigel: I don't think we've had all the horizontal review
   feedback yet. Not clear if i18n is done yet. We have review
   feedback from ARIB

   Pierre: i18n has completed the review

   Nigel: It looked like APA is considering feedback

   [21]APA tracking issue for IMSC 1.3

     [21] https://github.com/w3c/a11y-tracking/issues/252


   Nigel: Issue 116 is closed. They want us to think about
   assistive technology users. Good to address as soon as we can.

   Pierre: Their concern is how to make an HTML rendering
   accessible

   Nigel: They are concerned about how it relates to CSS
   vertical-align. You could have a situation where whatever is
   rendered in a screenreader the styling is lost

   Pierre: The fallback is to not have the superscript, which is
   fine

   Nigel: The sub and sup elements could be useful here. Is it OK
   for a rendering implementation that maps IMSC to HTML to use
   those instead of font variation position?

   Pierre: I'm leery of including very specific HTML rendering
   recommendations, as it changes often.
   … The browser bug threads say use vertical-align, for maximum
   compatibility

   Nigel: We don't want to get caught into that debate, but adding
   a note that vertical-align won't report property might be all
   that's needed

   Pierre: I'm OK doing that if it resolves their concern

   Pierre: They should propose the Note

   Nigel: Can ask APA about adding such a note

   SUMMARY: @nigelmegitt to ask APA if adding a note about
   implementations using vertical-align would address their
   concerns

    Response to ARIB

   Pierre: There were two comments not against IMSC1.3
   specifically. Let's figure out how to respond

   Nigel: Yes, let's you and I do that

  DAPT

   Nigel: HR feedback: Privacy said no concerns, i18n opened some
   issues, and no feedback from other groups

    Use zxx in place of an empty daptm:langSrc [22]w3c/dapt#322

     [22] https://github.com/w3c/dapt/issues/322


   [23]w3c/dapt#322

     [23] https://github.com/w3c/dapt/pull/322


   github: [24]w3c/dapt#322

     [24] https://github.com/w3c/dapt/pull/322


   Nigel: Feedback in [25]w3c/dapt#321 is that there's a tag for
   non-linguistic content
   … The zxx language tag means what we want here
   … I opened a PR, to day well-formed rather than valid. And
   previously the default was empty, now it's zxx, no semantic
   change.
   … Fuqiao said we could use und instead of zxx
   … Do we think und would make more sense? Then we'd need a rule
   that no content has a langSrc of und, and introduce an error
   state
   … Should we change the semantic, and require users to define
   it?

     [25] https://github.com/w3c/dapt/issues/321


   Cyril: We want to avoid creating wrong documents
   … The attribute is inheritable. I wonder, if the root isn't
   specified it'll have a default value, overridden at paragraph
   level
   … Don't know if I have a preference for undefined
   … It's easier to detect if the document was mistakenly left to
   the default, when it's und, rather than zxx

   Nigel: I think that makes sense
   … zxx only makes sense if it's audio description, but probably
   wrong for other types of transcript. Don't want to introduce a
   normative requirement on registry entries
   … Proposal is to change the default to und, and add a
   constraint that all completed text objects have a value that
   isn't und. Any other views?

   <atsushi> +1

   Pierre: So you'd require the langSrc attribute to be present?

   Nigel: Yes, and the computed value for text shall not be und.

   Pierre: Forcing people to put something where they might not
   understand, they'll put in bad values when they don't know

   Cyril: For other attributes, I'd say yes, but you'd know the
   language you're authoring against

   Pierre: If the tool forces you to put something, and you don't
   know about the weird corner cases, someone might put in a value
   just to stop the tool complaining
   … Is there a way that if you say nothing, it means "i don't
   know", no value if the attribute isn't present

   Cyril: Either put the default as undefined, and have semantics
   to say it should be set, or xx

   Nigel: Or include in the registry for represents, have a known
   value of langSrc to use in the original transcript

   Pierre: I'd recommend that the absence of the attribute means
   und

   Cyril: Yes

   Cyril: So we're saying the default is und but doesn't need to
   be overrridden by an actual language

   Andreas: It would be more transparent to have it specific, and
   an explicit value of undefined
   … Agree on having the default be undefined

   SUMMARY: @nigelmegitt to update the PR to make the default
   "und"

  WebVTT open issues

   Gary: Can skip this given the time available, TPAC is more
   urgent

  TPAC 2025 planning

   Nigel: I've made a wiki page

   [26]TPAC 2025 TTWG Wiki page

     [26] https://www.w3.org/wiki/TimedText/tpac2025


   Nigel: It has a section for participants to describe their
   arrival and departure. Useful to know who's coming and who's
   remote
   … You should all be able to edit
   … There's a section on Goals, moving our specs forward. We have
   joint meetings, with MEIG and with APA. Future work
   … Does anyone have topics to add to the agenda?
   … Joint meeting with MEIG, TTWG main meeting on Tuesday. I need
   to know timing constraints for particular topics, especially
   for remote participants
   … Thursday has TTWG/MEIG/APA joint meeting

   Andreas: In TPAC Seville we talked about the DVB intent to
   specify subtitle purpose metadata. That's now published, in TV
   Anytime. Could discuss again, see if it meets our expectations

   Nigel: Is it TTWG or MEIG thing?

   Andreas: one part is MEIG, but a specific part on the TV
   Anytime metadata model, was discussed in TTWG 2 years ago, this
   is more for subtitling experts

   Nigel: Having some time to talk about advances in
   implementations or user communities, who's using our specs and
   what for, could be valuable

   Andreas: Yes, sounds good
   … Activities around DVB TTML, for example

   Nigel: Other topics?

   Gary: A bunch of WebVTT topics. I'll be remote, so in the
   morning Japan time?
   … Question is scheduling that vs IMSC and TTML discussion
   … Timing-wise US west coast is a bit easier. For me, 9am in
   Japan would be 8pm locally

   Cyril: Not sure if I'll be there in person

   Nigel: We don't have many meetings between now and TPAC. Please
   contribute to the wiki offline
   … Gary, you could send email to the reflector to ask on
   scheduling

   Nigel: Should we cancel the 6 November TTWG meeting?

   Gary: Yes. I can't make October 23

   Nigel: So your last meeting before TPAC will be October 9

   Gary: I can do it async

  Meeting close

   Nigel: We're slightly over time, let's adjourn.
   … Next call is on October 9

   [27]October 9 agenda issue

     [27] https://github.com/w3c/ttwg/issues/317


   Nigel: Thank you everyone! [adjourns meeting]


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