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16:00:26 <trackbot> Meeting: Timed Text Working Group Teleconference
16:00:26 <trackbot> Date: 28 February 2019
16:00:31 <cyril> scribe: Cyril
16:00:44 <cyril> present: Cyril, Glenn, Gary
16:00:52 <cyril> Agenda: https://github.com/w3c/ttwg/issues/20
16:01:01 <cyril> Chair: Nigel
16:01:44 <plh> plh has joined #tt
16:02:13 <cyril> Present+ Pierre
16:02:25 <cyril> Present+ Nigel
16:03:36 <cyril> Topic: This meeting
16:03:46 <cyril> nigel: there are lots of AOB today
16:04:09 <cyril> ... profile registry, future reqs (probably nothing), TTML in RTP
16:04:13 <cyril> ... WebVTT ?
16:04:16 <cyril> gkatsev: yes
16:04:28 <cyril> nigel: charter draft, some issues with a PR
16:04:36 <cyril> Present+ Andreas
16:05:13 <cyril> nigel: a new issue on TTML and WebVTT mapping, poll on F2F
16:05:13 <atai2> atai2 has joined #tt
16:05:29 <cyril> ... historical content on mercurial
16:05:49 <cyril> ... tiny update on an ITU doc
16:06:10 <cyril> ... reminder that DST is coming to the US ahead of Europe, so meeting time shuffling needed in March
16:06:40 <cyril> atai2: possible liaisons with MPEG and the VR-IF regarding subs in VR/360
16:07:46 <cyril> Topic: TTML Profile Registry Actions, Pull Requests and Issues
16:08:13 <cyril> nigel: thank you Glenn for getting conclusions on the previous PR, just merged
16:08:38 <cyril> ... we need some reopening discussions with the section that describes possible way of discovery
16:08:44 <cyril> ... section 4.2
16:09:11 <cyril> ... glenn opened PR 53 that deletes the whole section
16:09:19 <cyril> ... I thought we agreed to move it to an informative annex
16:09:21 <pal> pal has joined #tt
16:09:42 <cyril> https://github.com/w3c/tt-profile-registry/issues/53
16:09:54 <cyril> glenn: there are 2 reasons to delete the section
16:10:23 <cyril> ... 1) the leading sentence is misleading at best
16:10:53 <cyril> ... it's possible that we define an algorithm not in TTML today
16:11:11 <cyril> ... but I don't want to define another one and leave it up to implementation
16:11:22 <cyril> ... if we do, we need to qualify the utility of this
16:11:33 <nigel> q+ to note that if we keep 4.2 then we need to say it applies to content profiles not processor profiles
16:11:34 <cyril> ... 2) it introduces another table
16:11:42 <cyril> ... that creates long maintenance issue
16:12:19 <cyril> ... it creates a second registry that has questionnable use
16:12:25 <cyril> ... overall, best to remove it
16:12:35 <nigel> q?
16:12:35 <cyril> ... seems in accordance to make the document shorter
16:12:38 <nigel> ack nigel
16:12:38 <Zakim> nigel, you wanted to note that if we keep 4.2 then we need to say it applies to content profiles not processor profiles
16:12:49 <cyril> nigel: definitely I would concur that it is confusing
16:13:00 <cyril> ... the document as a whole talks about processor profiles
16:13:09 <cyril> ... but that section seems to talk about content profiles
16:13:15 <cyril> ... and we don't talk about it
16:13:27 <cyril> ... on the point of maintenance, I don't think that's a strong point
16:13:37 <cyril> ... I don't see that as a prime factor
16:13:48 <cyril> ... the question is: is this table useful at all
16:13:58 <cyril> q+
16:14:05 <nigel> scribe: nigel
16:14:07 <nigel> ack c
16:14:16 <nigel> Cyril: I agree with Glenn, remove the section, make the document lean.
16:14:23 <nigel> scribe: cyril
16:14:36 <cyril> nigel: any other views?
16:14:45 <cyril> ... proposal is to remove 4.2
16:14:48 <cyril> ... any objection?
16:15:00 <cyril> ... anyone wanting to keep it in one form or moving it
16:15:06 <cyril> ... silence
16:15:16 <cyril> ... the proposal is adopted
16:15:25 <cyril> ... I will amend my PR comment
16:15:51 <cyril> glenn: that will remove a comment from cyril, we can close 2 or 3 issues as a side effect
16:16:58 <cyril> nigel: summary is there is still a bit of editorial work to solve the remaining issues
16:17:11 <cyril> glenn: I'll crunch through those
16:17:20 <cyril> glenn: mike asked an IANA review
16:17:33 <cyril> ... to resolve that one we'll have to get external review
16:17:43 <cyril> ... the codecs parameter is new
16:17:55 <cyril> nigel: no, it was in TTML 1 2nd edition
16:18:03 <cyril> ... the IANA page already includes codecs
16:18:13 <cyril> pal: let's not change at all if possible, no editorial change
16:18:23 <cyril> nigel: none of the PR have done so
16:18:34 <cyril> pal: great news
16:18:50 <cyril> nigel: we should treat that as a constraint for the future PR
16:19:16 <cyril> nigel: anything else?
16:19:18 <cyril> ... no
16:19:24 <cyril> Topic:  TTWG Future requirements
16:19:30 <cyril> nigel: anything to say?
16:19:36 <cyril> ... to raise about that?
16:19:47 <cyril> Topic: TTML in RTP IETF submission
16:19:55 <cyril> nigel: 4th draft has been added
16:20:00 <nigel> -> https://datatracker.ietf.org/doc/draft-sandford-payload-rtp-ttml/ latest draft
16:20:16 <cyril> ... this should resolve all the comments that we raised
16:21:08 <cyril> ... section 8 says no IANA action
16:21:22 <cyril> ... the one thing that we haven't fully concluded
16:21:27 <cyril> ... is the codecs parameter
16:21:39 <cyril> ... we now have a requirement that says it shall be in the SDP
16:22:01 <cyril> ... glenn if you could have a look at that and confirm that it removes the need for anything else
16:22:04 <cyril> glenn: ok
16:22:13 <nigel> q?
16:22:15 <cyril> nigel: we welcome any other feedback
16:22:34 <cyril> Topic: WebVTT Implementation Report
16:22:58 <cyril> gkatsev: after last week's meeting, I met with Silvia to talk about at risk stuffs
16:23:10 <cyril> ... we identified a couple of things to be marked at risk
16:23:26 <cyril> ... the style block is only supported by Safari and polyfilling is tricky and cannot be done on time
16:23:40 <cyril> ... collision avoidance with snap to line false
16:23:45 <cyril> ... and also some selectors
16:24:00 <cyril> ... if we remove those items from the rendering tests, we can reach 99% completion
16:24:24 <cyril> ... I'm going to work on marking those at risks and getting a new spec snapshot
16:24:36 <cyril> ... regions has basic support
16:24:45 <cyril> s/regions/FF/
16:24:51 <cyril> ... for regions
16:25:00 <cyril> ... and VLC has it too, so we have interop
16:25:36 <cyril> ... in FF, they have chosen to give a default background to boxes but Safari and VLC have not
16:25:41 <cyril> ... is FF following the spec?
16:26:08 <cyril> s/... is FF following the spec?/plh: is FF following the spec?/
16:26:12 <cyril> gkatsev: yes
16:26:36 <cyril> pal: I think either Chrome or FF are not following the spec regarding opacity
16:26:43 <cyril> ... I don't know how precise we want to be
16:26:52 <cyril> ... what the threshold is for passing
16:26:52 <atai2> q+
16:27:07 <cyril> nigel: what does the spec say about the background of regions
16:27:13 <cyril> atai2: thank you gkatsev for the update
16:27:33 <cyril> ... what does basic support for FF mean? what is the target?
16:27:50 <cyril> ... do they complement each other?
16:28:06 <cyril> gkatsev: the reason I'm saying it has 'basic' support
16:28:11 <cyril> ... it's because all the tests pass
16:28:35 <cyril> ... but for the scroll tests, the sizing in FF is a bit unexpected (not incorrect)
16:28:47 <cyril> ... but you can see a portion of the first cue as it goes out of the region
16:28:53 <cyril> ... it's not perfect
16:29:03 <cyril> ... but I think it is still within tolerance
16:29:13 <cyril> ... and just filed as an implementation bug
16:29:23 <cyril> nigel: does the spec talk about clipping
16:29:27 <cyril> gkatsev: I don't think so
16:29:35 <cyril> nigel: so then it would seem acceptable
16:29:43 <cyril> gkatsev: I'll verify
16:29:58 <cyril> ... everything else that I looked at, nothing is not implementable
16:30:19 <cyril> ... VLC is not implementing some of the style stuffs because it is allows
16:30:47 <cyril> gkatsev: at risk are: cue selector function with *, cue pseudo selectors with past and future
16:30:57 <plh> q+
16:30:57 <cyril> ... collision avoidance with snap to line false
16:31:03 <plh> ack atai
16:31:07 <cyril> ... and style block within the VTT file
16:31:29 <cyril> ... and cue selectors with region
16:31:47 <atai2> q+
16:31:52 <cyril> nigel: the style part is a big deal
16:31:58 <cyril> plh: why?
16:32:11 <cyril> nigel: because VLC would have no way to set styles
16:32:22 <cyril> ... no mechanism inside the document
16:32:35 <cyril> gkatsev: VLC has chosen not to implement that
16:32:45 <cyril> ... and the spec says that if you don't have a style engine you can
16:33:10 <cyril> pal: do the current tests adequately represent the spec?
16:33:15 <cyril> ... that's discussion a
16:33:34 <cyril> ... and discussion b is: is the spec adequate for some use cases?
16:33:39 <nigel> q+
16:33:41 <cyril> ... a) is very mechanical
16:33:52 <cyril> ... you check 2 implementations for each feature
16:33:58 <cyril> ... b) is a lot more complex
16:34:02 <nigel> ack plh
16:34:14 <cyril> plh: my thinking is that we need to publish ASAP with the features at risk
16:34:29 <cyril> ... if the group is OK we should give him power to do that
16:34:54 <cyril> ... then regarding styling and accessibility, we cannot answer before publication anyway
16:35:07 <nigel> q?
16:35:15 <cyril> ... but we can ask accessibility people
16:35:20 <nigel> ack atai2
16:35:23 <nigel> ack atai
16:35:29 <cyril> atai2: I agree with plh and pal
16:35:42 <cyril> ... if a feature is not implemented it needs to be removed
16:35:50 <cyril> ... but nigel point is also valid
16:36:12 <cyril> ... we have a lot of implementations using HLS and if there is no way to have styles
16:36:24 <cyril> ... that's a significant issue for accessibility
16:36:32 <cyril> q+
16:36:52 <cyril> ... if it's not implemented what can we do
16:36:57 <nigel> ack nigel
16:37:25 <cyril> nigel: to respond to plh's point, I think this group's job is to think about accessibility
16:37:31 <cyril> ... it is within our charter
16:37:49 <cyril> ... we can make the call to accept or not the features at risk because of accessibility
16:37:58 <gkatsev> q+
16:38:10 <cyril> ... we need consensus on the at risk list
16:38:30 <cyril> plh: the spec does already allow not to implement the style part today
16:38:37 <cyril> nigel: I don't think that's right
16:38:52 <cyril> plh: yes, there is a class of conformance without CSS
16:39:03 <plh> "All processing requirements in this specification apply, except parts of §6 Parsing that relate to stylesheets and CSS,"
16:39:09 <nigel> q?
16:39:16 <nigel> scribe: nigel
16:39:18 <nigel> ack cyr
16:39:32 <nigel> Cyril: We don't have a choice, either we publish what is implemented or we don't publish.
16:39:44 <nigel> .. We can't change what is implemented today, it is too late, whether or not we like it.
16:39:44 <pal> q+
16:39:52 <nigel> scribe: cyril
16:40:01 <nigel> ack g
16:40:30 <cyril> gkatsev: we can mark things at risk that today don't meet the criteria, but we can decide later if we remove or not
16:40:44 <cyril> ... the style block is something we can polyfill but we need more time
16:40:55 <nigel> q+
16:40:58 <cyril> ... we could potential meet the 2 implementations goal
16:41:16 <cyril> ... for VLC, from what I understand, because they don't have a CSS engine, they are not implementing the style block
16:41:22 <cyril> ... this is really CSS inside the file
16:41:27 <nigel> q?
16:41:51 <cyril> pal: what's missing is a WebVTT spec that reflects reality
16:42:15 <cyril> ... it's a reasonable plan to take the spec, identify at risk, publish that
16:42:30 <cyril> ... if removal of a feature creates deficiencies for accessibility, those can be noted
16:42:38 <cyril> ... and then we can decide on what we do
16:42:39 <nigel> ack pal
16:43:03 <cyril> ... I'm a pretty big proponent to have a spec that matches reality
16:43:20 <cyril> nigel: plh posted some text on style
16:43:44 <plh> q+
16:43:56 <cyril> ... if we mark at risk and meet exit criteria, the group would have agreed to publish without the feature
16:44:17 <cyril> ... we need to think very hard about allowing publication without any styling at all
16:44:35 <cyril> ... if you cannot indicate colors, I would probably object
16:44:39 <cyril> q+
16:44:47 <cyril> ack n
16:45:20 <cyril> pal: if the spec does not meet all criteria, maybe that could be acceptable
16:45:35 <cyril> plh: if you look at HTML, it does not say you have to implement CSS
16:45:44 <cyril> ... I don't see why we should have a different approach
16:45:53 <atai2> q+
16:46:05 <cyril> ... I agree the experience would not be a pleasant one or acceptable one
16:46:18 <cyril> ... but we don't require a specific profile of CSS to be implemented with HTML
16:46:30 <cyril> ... what we are doing today is marking at risk
16:46:47 <cyril> ... we would be blocking ourselves to start discussing if we remove it or not today
16:47:06 <cyril> ... there may be a case to make to keep the style box
16:47:12 <cyril> ... there are lots of engines out there
16:47:18 <cyril> ack p
16:47:24 <nigel> zakim, close queue
16:47:24 <Zakim> ok, nigel, the speaker queue is closed
16:47:33 <nigel> scribe: nigel
16:47:52 <nigel> Cyril: The goal is to publish what is implemented today,
16:48:05 <nigel> .. it doesn't mean that it requires BBC to implement it, there are other choices.
16:48:30 <nigel> .. Publication does not endorse the feature set, we can say it reflects reality.
16:48:34 <nigel> .. It's better than not having a spec.
16:48:43 <nigel> scribe: cyril
16:48:45 <nigel> q?
16:48:48 <cyril> ack c
16:48:52 <nigel> ack a
16:49:31 <cyril> nigel: please circulate a detailed proposal of what you want to mark at risk and we'll discuss again
16:49:34 <nigel> zakim, open q
16:49:34 <Zakim> I don't understand 'open q', nigel
16:49:37 <nigel> zakim, open queue
16:49:37 <Zakim> ok, nigel, the speaker queue is open
16:49:39 <cyril> Topic: TTWG Charter
16:49:59 <cyril> nigel: I've been reviewing the draft charter
16:50:05 <cyril> ... and the issues
16:50:11 <cyril> ... PR40
16:50:29 <cyril> ... plh we need to enable PR preview on this one
16:50:38 <cyril> plh: usually we don't on small repo, but sure
16:50:53 <cyril> nigel: PR40 is adding wording for TTML3 and module approach
16:51:06 <cyril> ... please have a look at if that works and look at the CSS charter for reference
16:51:20 <cyril> ... I've tried to adapt that "prior art"
16:51:34 <cyril> ... one question: there is a template section for adopting working drafts ...
16:51:40 <cyril> ... are they required?
16:51:43 <cyril> plh: yes
16:52:34 <cyril> nigel: please look at the current draft and raise issues for next week
16:52:35 <nigel> q?
16:52:45 <cyril> Topic: Hosting additional test/example resources
16:52:57 <cyril> nigel: we made a bit of progress offline
16:53:10 <cyril> ... summary is that we are working out what we do with the video resources
16:53:20 <cyril> plh: we don't need to solve that here
16:53:26 <cyril> ... are they BSD?
16:53:36 <cyril> pal: they are referenced from the repo
16:53:47 <cyril> plh: I'll check with Wendy
16:54:00 <cyril> plh: regarding the forking, I'm ok with it
16:54:10 <cyril> ... you'll check when you want to merge
16:54:28 <cyril> pal: let me know as soon as you can if any additional info is needed by fox
16:55:47 <cyril> Topic: TTML to WebVTT Mapping - new issue
16:55:59 <cyril> nigel: John Birch noticed a possible error and raised an issue
16:56:10 <cyril> ... anyone wanting to take the editorial role and fix the document?
16:56:17 <cyril> ... if so, please get in touch with me
16:56:30 <cyril> atai2: we said the document is on hold
16:56:44 <cyril> ... but I think I'm still one of the editor
16:56:54 <cyril> ... it's really out of date
16:57:09 <cyril> ... I'm not sure what sense it would have to fix just one error
16:57:17 <cyril> ... not sure what use it has right now
16:57:24 <cyril> ... I did not review the issue
16:57:32 <cyril> ... I assume the fix is small
16:57:49 <cyril> Topic: F2F poll
16:57:53 <cyril> nigel: still open
16:58:10 <cyril> ... but I noticed while looking at our charter that says we will meet at TPAC
16:58:23 <cyril> ... which means at least I should arrange a meeting for TPAC
16:58:36 <cyril> ... I raised an issue about the charter in case we need
16:59:08 <nigel> -> https://www.w3.org/2002/09/wbs/34314/2019_September-F2F/ WBS Poll
16:59:42 <nigel> scribe: nigel
16:59:52 <nigel> Topic: Mercurial decommissioning
17:00:17 <nigel> Nigel: I'll a message to the reflector - if there's anything of ours on Mercurial still that we need to migrate, please
17:00:20 <nigel> .. let me know.
17:00:44 <nigel> Pierre: Let's make a backup and store it somewhere
17:00:54 <nigel> Philippe: We're going to have access to zip files of the repos themselves.
17:01:07 <nigel> .. That's already provided. Worse case scenario is download that zip file.
17:01:10 <nigel> Pierre: Thanks
17:01:16 <nigel> Nigel: That's good to know, thank you.
17:01:27 <nigel> Topic:  ITU-R BT.2342 Update
17:01:49 <nigel> Nigel: I'm in process of submitting an update to the above ITU document to bring it up to date, to be considered in
17:01:55 <nigel> .. the March ITU-R meeting.
17:02:00 <nigel> .. For info only.
17:02:14 <nigel> Topic: DST upcoming times
17:02:37 <nigel> Nigel: The US is entering DST soon, a while before Europe so I'll propose new UTC meeting times hopefully to
17:02:42 <nigel> .. minimise disruption.
17:03:52 <nigel> Pierre: For the meeting at TPAC, is the goal still to determine following March 7 the final plan based on the poll,
17:03:58 <nigel> .. regardless of the Charter?
17:04:16 <nigel> .. For those attending IBC there will be significant international flight gymnastics and we have to set the date soon.
17:04:25 <nigel> Philippe: We're rechartering between now and TPAC.
17:04:30 <nigel> Pierre: Understood, thanks.
17:04:59 <nigel> Nigel: My plan is to agree after March 7, yes.
17:05:18 <nigel> Nigel: The draft Charter would need a pull request.
17:05:30 <nigel> Philippe: I can tell you that rule is not actually enforced!
17:05:42 <nigel> Topic: Possible liaisons with MPEG and VR-IF about 360º subtitle positioning
17:05:54 <nigel> Andreas: Let's discuss this next week.
17:05:59 <nigel> Topic: Meeting close
17:06:11 <atai2> atai2 has left #tt
17:06:28 <nigel> Nigel: Thanks everyone, apologies for running 5 minutes over. [adjourns meeting]
17:06:34 <nigel> rrsagent, make minutes
17:06:34 <RRSAgent> I have made the request to generate https://www.w3.org/2019/02/28-tt-minutes.html nigel
17:08:17 <nigel> Regrets+ Thierry
17:13:54 <nigel> s/long maintenance/long-term maintenance
17:16:49 <nigel> s/because VLC would have no way/because video only players like VLC would have no way
17:17:47 <nigel> s/that's a significant issue for accessibility/that's a significant issue for accessibility [if colours cannot be used to indicate speakers]
17:19:20 <nigel> s/I would probably object/I would need to think hard about it and would probably object: it would mean that WebVTT cannot be used to meet the accessibility requirements of the UK's audience.
17:20:02 <nigel> s/please circulate a detailed proposal/Gary, please circulate a detailed proposal
17:21:13 <nigel> s/plh: yes/plh: yes if they have been published, otherwise use the ED and don't add the call for exlusions
17:21:38 <nigel> s/please look at the current draft and raise issues for next week/please look at the current draft and raise issues - I'll try to open pull requests next week
17:22:02 <nigel> s/we don't need to solve that here/we don't need to solve that right now on this call
17:22:24 <nigel> s/they are referenced from the repo/Yes, they are referenced from the repo and have the same license as on the repo
17:22:58 <nigel> s/still open/still open until 23:59, Boston time on 2019-03-07
17:23:28 <nigel> s/I'll a message to the reflector/I'll send a message to the reflector
17:24:12 <nigel> rrsagent, make minutes
17:24:12 <RRSAgent> I have made the request to generate https://www.w3.org/2019/02/28-tt-minutes.html nigel
17:25:29 <nigel> Present+ Philippe
17:25:30 <nigel> rrsagent, make minutes
17:25:30 <RRSAgent> I have made the request to generate https://www.w3.org/2019/02/28-tt-minutes.html nigel
17:28:11 <nigel> Log: https://www.w3.org/2019/02/28-tt-irc
17:28:12 <nigel> rrsagent, make minutes
17:28:12 <RRSAgent> I have made the request to generate https://www.w3.org/2019/02/28-tt-minutes.html nigel
17:28:38 <nigel> scribeOptions: -final -noEmbedDiagnostics
17:28:41 <nigel> rrsagent, make minutes
17:28:41 <RRSAgent> I have made the request to generate https://www.w3.org/2019/02/28-tt-minutes.html nigel
19:28:35 <Zakim> Zakim has left #tt