Meeting minutes
This meeting
Nigel: I've added to the agenda two TTML2 topics, and a placeholder for the workplan for this year.
… The TTML2 topics are issue 1215 about lineHeight and Exiting CR.
… Any other business?
group: [no other business]
Permit implementations to use fontSize and fontFamily when computing line height w3c/ttml2#1215
github: https://
Glenn: I'm able to open a PR maybe by tomorrow as per Nigel's most recent proposal. I'm fine with that approach.
Nigel: Okay, great, thank you.
Glenn: I wanted to add one comment, that I didn't necessarily make it clear.
… Based on my analysis, my conclusion was that an implementation that does _not_ take font*** into account now is non-compliant.
… Your original description was that some implementations might not follow that semantic, and my conclusion was that
… not doing so would make it non-compliant according to the letter of the current spec.
… I would agree that it is not easy to pull out that thread of logic from the spec because it requires a fairly good
… understanding of XSL-FO, which since we're talking about CSS might make one wonder.
… The semantic model is fairly clear.
… The way we did the derivation of attributes might make it seem like it's not semantically tied to the XSL-FO definitions.
Nigel: Thanks for that.
SUMMARY: @skynavga to prepare a pull request on TTML2
TTML2 - Exiting CR
nigel: my goal was to find out what minimally we needed to do
… the IR contains a large number of tests
… what wasn't clear to me was how it related to the exit criteria
… [reading the exit criteria]
… there is a document that lists all the changes
… I went through all of the substantive changes
… and tried to map them to the features
… some don't and some do
… from each PR to the feature or features
… what sort of tests do we need: validation vs presentation
… there are 22 changes made
… that related to a feature
… there are fewer features because some changes relate to multiple features
… when we look at all of the tests that are in the current IR, some of them test things that are not changed in the 2nd ed
… they are good tests, nothing wrong, but they are not needed for the exit criteria
… my goal is to simplify
… [working on an example in the spreadsheet ...]
nigel: looks possible indicate if we could pass exit criteria for a change
glenn: in that language you quoted about the definition of what needs to be tested, keep in mind that the word 'feature' can mean one of 2 things and it's not defined precisely.
… It could mean a semantic feature or a designated feature with a #
… second comment is that when I created the tests my model was for which PR required a test, I used whether we decided if it was substantive or not
… lastly, you said a validating processor can flag the error, I think you meant 'must' flag the error
… otherwise it's not a compliant validator
nigel: on the last one, it's not clear what a validation processor needs to do if the requirement is for the presentation processor to ignore
glenn: we don't say that a validating processor must do X, we don't do that in general
… definition of valid vs invalid is defined further up in the document
… even though that particular text does not use a must, it is still a must if you adhere to other semantics
nigel: on the point on the 'substantive' issues, I also factored that
… I also found anyway a significant number of tests that don't relate to 2nd edition changes
… we could remove them from the IR
glenn: I'm surprised of that
cyril: me too
nigel: I do plan on sharing the spreadsheet
glenn: one example would be interesting to check your logic
nigel: there are a bunch of ISD related tests
… and I don't think there were any substantive changes to ISD
glenn: it had to do with the fact that the definition of the size attribute was changed to xsd:nonNegativeDefinition to a new one
nigel: there was a change like that
… maybe I misunderstood that
glenn: all the tests are changing that semantic change in TTML2 2nd ed
… I'm pretty sure all the changes can be traced back to a real change
… if not, let me know, I can try to give a rationale
nigel: anyway there are definitely tests which we are not able to demonstrate indep implementations
pal: another column could be added as ttval
… which is a constrained validator for TTML2
… I'm not sure it's worth spending a lot of time on ttval by if a minor change can clean some rows, maybe we should do it
nigel: the other observation is about the structure of the IR
… the structure of the IR doesn't match the exit criteria
… in several cases, you discover that the features are implemented by 2 implementations but the current report does not show that
… it should be more traceable and easier to see the results
… that would help us check if we pass the exit criteria
glenn: I recall that earlier we required 2 validation implementations and 2 presentation implementations
… you're suggesting changing that?
glenn: yes
… I won't argue with that but for the 1st edition we went beyond that
nigel: I haven't checked the 1st edition exit criteria but in this case we need 2 implementations total
… we currently have 2 reports: TTV and BBC but we could report ttval and imscjs
glenn: although I haven't filled in the table, I have made progress on some of them (shear, opacity, ruby ...)
… I think there is only or 2 (font selection strategy lineheight normal) that I did not touch
… I don't have audio playback on TTPE
nigel: for audio, we probably already have a pass already because TTV does validation and Adhere passes presentation
… this is one example of one feature where we have 2 implementations
glenn: this model of IR was created by Cyril by taking the first IR and plugging in the relevant entries for the 2nd edition
… we had a stronger requirement in the 1st edition
… I don't have any objections to use a new model for the IR
cyril: it would be good to know if the tests are relevant for IMSC
nigel: I think I have done that pass already
… so I should have that information, but that's a good idea
nigel: I also tried to map the current tests in the IR to the changed features
… I was doing it manually and realized it's already in the JSON files
… so my next task is try to extract the 'since2e' tests
cyril: the purpose would be to rewrite the IR with feature, tests, implementations
nigel: if anybody has lines of code, please let me know otherwise I'll go ahead
glenn: we are using the same manifest for different versions
nigel: it's really useful
glenn: nothing is using and I haven't validated it
nigel: any other thoughts/questions/comments on exit CR for TTML2?
nigel: I'm reassured from this discussion that we can do this if we focus on it
Placeholder for workplan for this year
nigel: last time the things that people wanted to work on was WebVTT and TTML2 to Rec
… and beginning the journey of user customization
nigel: does anybody has anything else?
glenn: I was watching an movie about the creation of the Oxford dictionnary that took a while and hope we can be faster than that
pal: thanks so much for your work helping us get TTML2 to Rec
… on the customization thing, it would be great to get the world to agree on a framework to customization
… I would caution us to do that on our own
… going down one path that works well for one constituent
… anything we can do to get people on the table is great
nigel: as having worked on a fork of IMSC.js to add some customization in a particular work, I could be one constituent for who it works but I'm aware it might not work for others and don't want to impose a "BBC" solution
pal: one thing we could do is: many of us are involved in many forums and we could share that
… we could also draft something and share through liaisons
nigel: that'd be a good first step
pal: the privacy aspect is not something that many folks think about
… so including in the problem statement would be useful
nigel: not everybody share the same view of the possible impact
… it needs thoughts and considerations
… but I don't think it's a problem that concerns everybody
nigel: for people who were not at the meeting last time, and if you have topics to add, I'm happy to add them, discuss here or have a private chat
… we are chartered till the end of this year
… I wonder if there is a view that having got to IMSC1.2 and TTML2 that this group has completed its work
… have a feeling that some people think that
… and it does not feel right
… it'd be interesting to know the problem space that needs further work
pal: we've reached an inflexion point in market adoption
… and until we have broad adoption, I don't expect more spec work
… people in this call are pioneers
… we'll see much much broader adoption
… and as new people come in we'll have more issues
… I expect this year and maybe the next year to be quiet
… but I'm not a big fan of saying we're done
gkatsev: I wonder if the work, the meta work TTML to WebVTT draft, could be interesting
nigel: in terms of spec work, I'd like to push the Audio Description Profile of TTML2
… I expect spec work
… it falls in the category of additional work to use the core specs
<atsushi> https://
<nigel> Gary: I just saw the notice that WCAG 3 work has begun - maybe there's work we should do to help them with accessibility for subtitles and captions.
nigel: they've just released the FPWD
… it may have an impact on the customization work
Cyril: In general the topic of subtitle quality is of interest to Netflix.
… I don't know if the group would be happy to work in this direction,
… facilitating verification of reading speed, or detections of errors, for example typos, missing words.
… We had an interesting session at Netflix where we brought in Deaf customers and asked them what they were missing
… when it comes to subtitles. Maybe we could do the same in W3C, ask users of subtitles what is missing,
… what would help them, identify gaps that we could fill to help them.
Nigel: That's an interesting point - our core constituency in W3C is the users and we have very little direct engagement from
… users, so there's definitely something there.
Cyril: W3C has access to a lot of communities, so maybe it is a good opportunity to reach out and find out if there are frustrations
… with how subtitles are done in general.
Andreas: That's a really important point - the question is if it is a topic for a technically focused group.
Nigel: True, there may be a crossover for example - is there a technical solution to varying the amount of editing and the word rate?
Atsushi: We could make a video to show at the AC meeting to show the possible directions of our work.
Meeting close
Nigel: We're a few minutes over today, so let's adjourn. Thanks everyone. [adjourns meeting]