W3C

Timed Text Working Group Teleconference

21 Jun 2018

See also: IRC log

Attendees

Present
Nigel, Thierry, Pierre, Cyril, Glenn
Regrets
Andreas
Chair
Nigel
Scribe
nigel

Contents


<scribe> scribe: nigel

This meeting

Glenn: [can only stay 45 minutes]

Nigel: Thanks for letting us know.
... Any other time constraints from anyone?

group: [silence]

Nigel: Today we have TTML2 issues if there are any for CR2, and any comments to be
... raised on the CfC.
... I should also raise the way that we are responding to comments raised during the CfC period.
... I don't think we have anything on TTML1. Anything on IMSC?

Pierre: There's one issue we ought to discuss, #372 re rw and rh, because you were surprised Nigel.

Nigel: Yes, let's add that.

Pierre: Also, based on feedback I've received I'm about to open another issue against the
... requirements for rubyAlign which we could usefully discuss. It's already there actually.
... Actually we already discussed rubyAlign so we don't need to cover that.

Nigel: We have one action on CSS.

Glenn: I have a couple of issues to discuss on TTML2.
... There are 5 pull requests approved pending merge.

Nigel: Let's come to that, just doing the agenda now.

Glenn: I have a couple of items on TTML2 to get to.

Nigel: I don't expect anything on WebVTT. I haven't got a TPAC agenda item, but just to
... remind everyone registration is open.
... I've started to work on a list of topics to cover in a potential joint meeting with the M&E IG
... which I will share.
... Anything else for the agenda today?

group: [silence]

Nigel: Ok let's go.

TTML2 CR2

Nigel: Status report: CfC is more than half way through and there are some pull requests
... that address comments received during the CfC period. I want to treat those as CfC
... review comments and merge the fixes for those soon, but alert everyone to the fact
... that is happening and encourage you to be aware when reviewing.
... We have 5 approved pull requests pending merge, and I would propose that we merge
... them as soon as possible.
... Any objections to doing that?

Pierre: Not an objection, just confirmation that
... changes to the feature list are going to be treated editorially, so we can make those
... changes prior to PR?

Glenn: I would support that.

Pierre: I thought we had discussed it.

Glenn: I think you could argue it both ways. The feature system is on the one hand a meta-feature
... in the sense that it is about features and it is not defining new features but labelling them.
... On the other hand the standard profiles are normative so every time we add or change
... one of the profiles files it is changing some normative text in the document. I would
... prefer to take your point of view.

Pierre: I agree with your assessment.

Glenn: If we do it that way then we should say that in the SoTD to give ourselves permission
... to do that, which could result in objections from external readers that we would have
... to deal with. We should raise that in the transition request.

Nigel: The transition request has gone through but we can amend it.
... I'm not hugely comfortable with this.

Pierre: If we are not comfortable with it there may be alternatives but we should talk about
... it because there's a significant risk that we may have to modify features and the way
... they are formulated, just because of the sheer number of them.

Glenn: Changing the feature list is not adding or subtracting syntactic or semantic
... components of the specification.

Nigel: Here's a test: if an implementation supported a feature and that feature definition
... was changed then it could cause that implementation to become non-conformant, so
... from that point of view it is a normative provision and the change would be substantive.

Pierre: I agree.

Glenn: I agree.

Pierre: Then if we don't give ourselves that permission then what can we do?

Glenn: We can move it to TTML2 2nd Ed. We could note informatively that we intend to
... make certain changes but that due to timing we were not able to do it in 1st Ed.

Nigel: Previously we tried to make editions non-substantive in change.

Glenn: It would have to go through the CR process again.
... I wouldn't be surprised if we don't have other normative changes given the large number
... of features.

Pierre: I understand the rules as they're written right now, but this is pretty inefficient.
... Refactoring features is highly unlikely in practice to cause interoperability issues.

Nigel: I disagree.

Pierre: Can you point to such an implementation?

Glenn: Back to the point about making implementations non-compliant, it depends on the
... implementation. If the implementation depends on the override route, the first processing
... step of construct effective processor profile, then the implementation can set it to
... whatever it wants. How many processors will not take that route?

Nigel: We have to apply this rule to content conformance and that is more likely to be
... affected.

Glenn: If you define a content profile and use it for validation and then add a new feature
... that could not have been prohibited but add that prohibition based on the new feature
... then that's not going to be a problem. If you change the semantics of existing designators
... then you may end up prohibiting syntax that was not previously prohibited.

Nigel: If you're going to create the content profile mechanism then you have to allow it to
... be used safely.

Glenn: Ok. Clearly we can make changes on the way to 2nd Ed if we go through a CR process.
... So going back to the question about practical issue? I am of a mind that it is very low risk
... in causing a practical issue.

Nigel: That may be true, but it's not the test.

Glenn: That's correct.
... If we have a consensus in the group we can present that.

Nigel: Can I make a proposal that we add a bullet to the at risk feature list to notify readers
... that the definitions of feature designators may change. If we can do that for features
... and then make the substantive change at PR then I'm willing to see if we can do it for
... feature designators too.

Glenn: I like it.
... Just adding a #profile-version-2 bullet to the at risk list might do it.

Nigel: My understanding is that the at risk list is for features that can be dropped but not
... changed.

Thierry: You're only allowed "drop".
... If you change a feature and it is substantial then you have to issue a new CR.

Nigel: Pierre, are you concerned that you won't be able to complete a review of the TTML2
... feature designators during the review period?

Pierre: I expect to be done ahead of next week.

Nigel: In that case do we really need to worry about this?

Glenn: I'd be satisfied to not change the at risk list and if we get a request to change then
... use the standard route to deal with it, i.e. to add informative text until the next edition.

Nigel: I think that might be the best way.

Glenn: We already have a changes document. Eventually we will probably have a new section
... changes from CR2 to PR and by definition they would all need to be marked as editorial
... but we could prominently point out editorial changes of this type, that are warnings to
... the reader that something we found will be changed in the near future.

Nigel: Sounds like a good idea to me.
... I think we've circled round on this one and concluded that we will take no action.
... Any other views?
...
... Ok that's a 'no' so let's move on.
... This arose from the question about merging approved pull requests now. Any other
... questions or points on that?
...
... I'm taking silence as assent, so Editor(s) you can go ahead and merge the following pull
... requests: #836, #842, #843, #844 and #845.
... Noting that 843, 844 and 845 are labelled "substantive".
... Any more issues from you on TTML2 Glenn?

Glenn: No.

Nigel: The other point I wanted to raise is that we're making change to the document
... during the CfC and it would seem fair to allow it to stabilise. Are there any other
... pull requests expected?

Glenn: There's one for issue 830 and the other for 834 which tweaks the base-related
... features. It is going to involve adding a new feature called #base-general. To make it
... consistent with other definitions and the ability to prohibit the more general use of #base

Nigel: There are several editorial issues too.

Pierre: Glenn and I discussed 846 and realised it hadn't been opened as an issue yet.
... I expect to be done tomorrow with my review so hopefully we'll be very close tomorrow.

Nigel: Can we set a target to merge all the pull requests by the end of tomorrow?

Pierre: Monday is more realistic.

Glenn: I agree.

Nigel: OK
... I issued the CfC on Wednesday 13th June, so end of Tuesday is the end of the CfC.
... So that gives 1 day for final post-pull-request-merge reviews before the end of the CfC.
... It's pushing the limits a little!

Glenn: Starting on the 26th, if we finish merges on the Monday, I plan to do the normal
... pubrules and link checking which requires some minor tweaks which will require at least
... one pull request. I'll need someone at hand to approve those quickly so I can merge them.
... By the end of the 27th I need a package to send to staff for upload for CR2 if it is going
... to be published on the 28th.

Thierry: The webmaster usually needs 2 days.

Glenn: If we get that done on the 26th would that be adequate?

Thierry: Yes it would be better at the end of the 26th if you can submit a package then
... I can take care of it late on the Tuesday or early morning Wednesday my time.

Glenn: OK I'll make that a date then. I'll probably start doing the pubrules and have it done
... by the 25th as well.

Nigel: That'd be good, thank you.

Glenn: I'll need help from another committer who can approve requests over the weekend.

Pierre: I plan to be around.

Nigel: With notice I will be able to also.

Glenn: If you could be able to check your email once a day between now and Monday that
... would be adequate.

Nigel: Ok, with the proviso that if there's anything strange or unexpected or complicated
... then I will probably block merging. We really need to ramp down the significance of
... any changes from now on!

Pierre: +1 with a proviso that we need to avoid substantial changes. But if there is a real
... blocker then it is not a reasonable answer to wait until 2nd Ed. especially if everyone agrees on the solution.

Nigel: If something substantive does come up that needs a significant change then I would
... rather wait a few more days now than wait until 2nd Ed.

Pierre: Exactly.

Nigel: Included in the scope of those changes to be merged as soon as possible is the
... branch with the updates to changes on that you were working on Glenn.

Glenn: I can get that done by tomorrow.

Nigel: Then we can modify the transition request to point to the ED.

Glenn: [has to drop off the call]

IMSC 1.1 requirements

Nigel: I think we had one issue to look at, #372.

Consider TTML feature(s) for rw/rh <length> units imsc#372

github: https://github.com/w3c/imsc/issues/372

Nigel: My understanding of rw and rh was that they are beneficial especially with fontSize.

Pierre: Today you can achieve the same effect using `c`. It's not pretty but you can achieve
... that effect.
... We have discussed those requirements for many months and nobody has suggested we
... add them. I think it is in the "too late" category. I'd be more sympathetic if there were no
... other way to achieve it.

Nigel: Why are we too late?

Pierre: We are about to go to CR2 and there's a cost for supporting container related dimensions.

Nigel: A syntactic cost, given that the semantic is already feasible.

Cyril: It's not because it's been there for months that we cannot change it. We have to
... acknowledge we have mostly been working on TTML2 to finish it, so we should give
... ourselves some quality time to look again at the requirements for IMSC 1.1.

Nigel: +1 My time has been taken up by TTML2 mainly and I would like that opportunity.

Pierre: There's a cost to implementing it.
... So far nobody has made the argument why it is required. Don't get me wrong, I think
... it might be useful, but just nobody has explained why it is required.

Nigel: From my perspective the requirement is driven by the errors that I see when QAing
... TTML documents that I see, where people get the % calculations wrong.

Pierre: I don't expect anyone to adopt it.

Nigel: If it is absent from IMSC 1.1 then hypothetically EBU could not adopt it say in EBU-TT-D.

Pierre: If there were a liaison from EBU saying they wanted it then it would make the argument,
... but there is not one.

Nigel: I'm making this comment from my own experience, that c units cause difficulties
... and we should move towards rw and rh.

Cyril: I don't want to take a closed decision now - I need time to think about this.

Pierre: If this is needed then it should be raised as an issue against the requirements.

Nigel: Arguably Stefan has raised this issue on the wrong repo.

Pierre: Cyril, if Netflix is interested in adding rw and rh I ask that you do it super soon so
... we can get it in and get it done.

Cyril: I don't think we need it but I will cross check today or tomorrow.

Pierre: Super. Nigel, if EBU has IMSC 1.1 adoption on its roadmap and has strong feelings
... about rw and rh it would be good to know.

Nigel: I am not expecting any such statement.

Pierre: Or from anyone who plans to use IMSC 1.1 and has substantive input, now is the time.

Nigel: I've raised w3c/imsc-vnext-reqs#33 for this.

SUMMARY: Feature discussed, different viewpoints currently remain, requirements issue raised.

github-bot, end topic

IMSC 1.1

Pierre: I'm making great progress and should have something to present for review later
... today, refactoring the features table to match TTML2 and fix some of the outstanding issues.

Nigel: Great! Did you have a view on the labels and colours question?

Pierre: Yes, I really liked where you and Stefan ended up. I plan to implement something
... along the lines of what you have, putting the background and rounded corners on the
... permitted/deprecated/permitted-deprecated label itself.

Nigel: Looking forward to seeing that.

Pierre: Thank you for doing all the prototyping work, that makes it a lot easier.
... I plan to address that at the last moment when we are happy with the features table.
... Can we talk about #366?

tts:position should be allowed on region only imsc#366

github: https://github.com/w3c/imsc/issues/366

Pierre: My impression is that we have trained people not to use origin and extent on content
... elements. Certainly in IMF and ATSC we have trained people not to do it.
... imsc.js and TTPE and EBU-TT-D does not support it, so in fact I think the trend has
... been the opposite, that we have reiterated that you cannot do it. We have been saying
... that for the past 2 years and I'm finally getting to the point where I'm not seeing it anymore.

Nigel: Now I really want to make sure it is on the at risk list for TTML2 because I really
... don't want to support it.

Pierre: Based on my experience in imsc.js the feature really breaks the way TTML was
... designed. Unless someone stands up to say they really want it I don't think we should do it.

Nigel: It is not on the at risk list for TTML2 CR2.

Pierre: TTPE doesn't support it in TTML1, I'm not sure if it supports it in TTML2.

Nigel: Does anyone want to take the action to raise an issue to add the
... `#region-implied-animation ` to the at risk list for TTML2?

Pierre: I think it's reasonable to add it.

Nigel: If we can close this meeting early then I'll go ahead and do that.
... Going back to the issue you want to only allow position on region? Is that only on text profile?

Pierre: The same restrictions on tts:origin should be placed on tts:position, whatever those are.

Nigel: Don't you want position on image?

Pierre: You put it on the region that the image is in.

Nigel: And you only allow one image per region?

Pierre: Correct, just like in IMSC1.

RESOLUTION: We will not support `#region-implied-animation ` in IMSC 1.1.

Nigel: We also have another resolution to do what the issue requests.

RESOLUTION: Apply the same constraints that exist on `tts:origin` to `tts:position`.

github-bot, end topic

CSS actions review

action-512?

<trackbot> action-512 -- Pierre-Anthony Lemieux to Raise an issue with css wg requesting support for lineshear -- due 2018-06-21 -- OPEN

<trackbot> https://www.w3.org/AudioVideo/TT/tracker/actions/512

Nigel: The due date is today!

Pierre: Realistically I will not get to this for another two weeks or so.

Nigel: I've updated the due date to 5th July.

Meeting close

Nigel: We've completed our agenda for today, thank you everyone. [adjourns meeting]

Summary of Action Items

Summary of Resolutions

  1. We will not support `#region-implied-animation ` in IMSC 1.1.
  2. Apply the same constraints that exist on `tts:origin` to `tts:position`.
[End of minutes]

Minutes formatted by David Booth's scribe.perl version 1.152 (CVS log)
$Date: 2018/06/21 15:40:51 $