IRC log of tt on 2018-10-23

Timestamps are in UTC.

06:59:12 [RRSAgent]
RRSAgent has joined #tt
06:59:12 [RRSAgent]
logging to
06:59:14 [trackbot]
RRSAgent, make logs public
06:59:15 [Zakim]
Zakim has joined #tt
06:59:16 [trackbot]
Meeting: Timed Text Working Group Teleconference
06:59:16 [trackbot]
Date: 23 October 2018
06:59:21 [nigel]
06:59:36 [nigel]
Present: Glenn, Nigel, Andreas
06:59:40 [nigel]
Chair: Nigel
06:59:42 [nigel]
scribe: nigel
06:59:48 [nigel]
Topic: Agenda for today
07:00:12 [nigel]
Nigel: Good morning everyone, let's do introductions.
07:00:21 [atai]
atai has joined #tt
07:00:23 [nigel]
Nigel: Nigel Megitt, BBC, Chair
07:00:32 [nigel]
Andreas: Andreas Tai, IRT
07:00:44 [nigel]
Glenn: Glenn Adams, Skynav, been working on TTML since 2003!
07:00:51 [nigel]
Nigel: Thank you, and observers.
07:01:13 [nigel]
Masaya: Masaya Ikeo, NHK
07:01:36 [nigel]
Geun: Geun Hyung Kim, HTML5 Converged Technology Forum (Korea)
07:02:18 [GeunHyung]
GeunHyung has joined #tt
07:02:46 [nigel]
Nigel: Today, we have Live subtitles and caption contribution, AC review feedback,
07:03:00 [nigel]
.. future requirements, and Audio profiles.
07:04:03 [nigel]
Nigel: Welcome, we have another observer:
07:04:22 [nigel]
Hiroshi: Hiroshi Fujisawa, NHK
07:04:32 [MasayaIkeo]
MasayaIkeo has joined #tt
07:05:32 [nigel]
Toshihiko: Toshihiko Yamakami, Access Co., Ltd
07:06:21 [nigel]
Andreas: For the future requirements topic, after lunch, a colleague may want to join on
07:06:34 [nigel]
.. the requirements for 360º subtitles and possibly other TPAC attendees may want to
07:06:52 [glenn]
glenn has joined #tt
07:06:52 [nigel]
.. join so if we can figure out a specific slot that would be great.
07:07:11 [nigel]
Nigel: If there are timing preferences we can be flexible - probably any time after 11:30 we can do.
07:07:23 [nigel]
Andreas: Thanks, I'll get back to the group on that.
07:07:36 [nigel]
Topic: Live Subtitle and Caption contribution
07:07:44 [nigel]
Nigel: I uploaded a short presentation:
07:08:01 [nigel]
-> Presentation on live subtitles and captions
07:08:12 [nigel]
Present+ Pierre
07:08:30 [nigel]
Pierre: Pierre Lemieux, Movielabs, Editor IMSC
07:09:36 [nigel]
Nigel: [presents slides]
07:10:32 [fujisawa]
fujisawa has joined #tt
07:18:24 [nigel]
Pierre: Question about the client device being unaware of live vs prepared source, and
07:18:38 [nigel]
.. the system being designed with that as a constraint.
07:18:42 [nigel]
Nigel: Yes, assume that is the case.
07:18:56 [nigel]
Glenn: The distribution packager might assign DTS or PTS?
07:19:14 [nigel]
Nigel: Yes, I should have added MPEG2 Transport Streams as a possible output, and we
07:19:28 [nigel]
.. should note that there is a DVB specification for insertion of TTML into MP2 TS.
07:23:11 [ericc]
ericc has joined #tt
07:39:43 [nigel]
Nigel: [slide on transport protocols] If there is timing information from the carriage
07:39:58 [nigel]
.. mechanism then that might need to be understood in relation to processing any
07:40:02 [nigel]
.. subtitle TTML document.
07:40:25 [nigel]
Glenn: Are you hoping an RTP packet will fit within a single UDP packet?
07:40:36 [nigel]
Nigel: In general that is likely to be true, but not necessarily.
07:41:14 [nigel]
Pierre: So you can't rely on the network providing you with ordered documents?
07:41:19 [nigel]
Nigel: Yes, that could be the case.
07:41:32 [nigel]
Pierre: So the protocol you use has to be able to handle non-sequential document transmission?
07:41:36 [nigel]
Nigel: Yes, potentially.
07:42:34 [nigel]
.. You do need to resolve the presentation in the end, and some deployments may
07:43:07 [nigel]
.. provide fixes for out of order delivery at the protocol level (WebSocket) or at the
07:43:45 [nigel]
.. application level and we need to deal with the whole range of possible operational conditions.
07:49:24 [fujisawa]
fujisawa has joined #tt
07:53:34 [fujisawa]
fujisawa has joined #tt
08:07:16 [nigel]
group: Discussion of options for defining the begin and end time of a TTML document.
08:25:55 [nigel]
Nigel: [proposal slide]
08:26:13 [nigel]
Glenn: I wouldn't object to using the ebu namespace as long we don't normatively
08:26:24 [nigel]
.. reference the EBU spec. I'm not willing to cross the rubicon when it comes to bringing
08:26:29 [nigel]
.. in non-W3C namespaces into TTML.
08:26:46 [nigel]
.. If it is published as a Rec track document and it refers to TTML and is a module that
08:26:50 [fujisawa]
fujisawa has joined #tt
08:26:58 [nigel]
.. blesses these features, using EBU namespace to define them, then that's okay with me.
08:27:09 [nigel]
.. If we have an assumption that we are going to pull that into TTML directly then I might
08:27:12 [nigel]
.. start having some discomfort.
08:27:24 [nigel]
Andreas: I think we are not there yet at this point in the discussion. First we have a problem
08:27:36 [nigel]
.. that we are trying to solve and we have a standard that is already out there. It is good
08:27:47 [nigel]
.. practice not to duplicate. What Nigel has proposed addresses a good part of this
08:28:00 [nigel]
.. scenario, and there has been a lot of discussion since 2012 on this with at least 3 years
08:28:12 [nigel]
.. regular active work on it, so I think it is worth looking at it. After reviewing this and
08:28:24 [nigel]
.. deciding that this is how we want to solve it then we can look at how to adopt it.
08:28:34 [nigel]
Glenn: Right, I just wanted to give fair warning about the questions I might have.
08:28:46 [nigel]
.. A question I have is why we need to do something in W3C?
08:29:01 [nigel]
.. Is it a profile of EBU-TT?
08:29:13 [nigel]
Andreas: Good question. It is limited to certain vocabulary and mainly has the constraints
08:29:24 [nigel]
.. from EBU-TT, which are not the same as for IMSC. It would be perfect to use the same
08:29:29 [nigel]
.. mechanism for all IMSC documents.
08:29:58 [nigel]
Nigel: That was my answer, it makes sense to bring these key semantics into the home
08:30:08 [nigel]
.. of TTML so that it can be applied to other profiles than EBU-TT.
08:30:28 [nigel]
Glenn: Is it an authoring guideline?
08:30:35 [nigel]
Nigel: Why would it be a guideline?
08:30:46 [nigel]
Glenn: It's not defining new technical features.
08:30:50 [nigel]
Nigel: It is indeed doing that.
08:31:03 [nigel]
Pierre: There might be technical features such as defining document times as mentioned.
08:31:16 [nigel]
.. A lot of the guidelines could be in the model, but I suspect there would be some
08:31:20 [nigel]
.. requirements and substantive features.
08:31:47 [nigel]
Nigel: [propose a break for 30 minutes]
08:31:49 [nigel]
rrsagent, make minutes
08:31:49 [RRSAgent]
I have made the request to generate nigel
08:44:38 [ericc]
ericc has joined #tt
09:00:46 [MasayaIkeo]
MasayaIkeo has joined #tt
09:08:11 [atai]
atai has joined #tt
09:12:19 [nigel]
Topic: Live subtitle contribution - discussion
09:12:37 [ericc]
ericc has joined #tt
09:12:57 [nigel]
Pierre: Is the proposal for an EBU Member Submission?
09:13:09 [nigel]
Nigel: It could be but I think it is not needed - the IPR can be contributed by EBU as
09:13:19 [nigel]
.. a member based on any work that we do in this group.
09:13:32 [nigel]
Andreas: There is a question for a member submission if it will be superseded by a future
09:13:48 [nigel]
.. W3C specification. The market condition is that people are pushing for implementation
09:13:57 [nigel]
.. of EBU-TT Live so we should be clear about what we want to do in W3C.
09:14:27 [nigel]
Pierre: This sounds more like an EBU discussion, W3C cannot require implementation.
09:14:51 [nigel]
Andreas: It could affect adoption though since work on an alternative may change views.
09:15:06 [nigel]
Pierre: That's an EBU decision. Anything could happen when a member submission arrives here.
09:15:18 [nigel]
Andreas: We can review the document as it is and then review what is needed. I don't see
09:15:31 [nigel]
.. a need for a member submission at the moment. What advantage do you see in EBU submitting one?
09:15:44 [nigel]
.. The spec is out there, everyone can use it, IPR issues should not be a problem.
09:15:59 [nigel]
Pierre: I can't speak for EBU but I would think that a member submission clarifies
09:16:13 [nigel]
.. significantly the scope of the effort, being live subtitles within the member submission
09:16:18 [nigel]
.. scope rather than live subtitles in general.
09:16:35 [nigel]
.. IMSC ended up different from CFF-TT for good reason, but the scope of the features
09:16:48 [nigel]
.. for instance was set by the member submission. It would help.
09:17:01 [nigel]
Andreas: The different arguments that led other W3C members to make submission is more
09:17:14 [nigel]
.. internal, how to move on with some standardisation. In the past submissions are
09:17:31 [nigel]
.. submitted to W3C, then carefully reviewed, when W3C should take over certain
09:17:34 [nigel]
.. standardisation.
09:17:48 [nigel]
Pierre: For instance, CFF-TT - the Ultraviolet members and the larger community felt that
09:18:01 [nigel]
.. it would be beneficial if something like that specification were to be standardised by an
09:18:15 [nigel]
.. organisation like W3C. That was a decision by that community to do that. But it was not
09:18:29 [nigel]
.. happenstance. Here, I think it is up to EBU and its members and community to have an
09:18:41 [nigel]
.. opinion on whether or not standardisation by W3C helps or not.
09:18:51 [nigel]
.. It might not help if it changes the specification in a way that is not good for that
09:18:55 [nigel]
.. community. You tell me.
09:19:05 [nigel]
Andreas: We are not there yet. This group has not decided yet.
09:19:09 [nigel]
Pierre: Live is really important.
09:19:20 [nigel]
Andreas: Yes, this is something we need to discuss. What is in scope for this group?
09:19:29 [nigel]
Pierre: The industry is interested in live, period.
09:19:58 [nigel]
.. It is a really important use case.
09:21:36 [nigel]
Nigel: [repeats goal from earlier[
09:21:42 [nigel]
09:21:57 [nigel]
Pierre: If the goal is to arrive at how to create a set of IMSC documents in a live environment...
09:22:10 [nigel]
Andreas: What Nigel said, and other EBU members, is there is support to make EBU-TT Live
09:22:21 [nigel]
.. a subset similar to how EBU-TT-D is a subset of IMSC Text Profile.
09:22:23 [Zakim]
Zakim has left #tt
09:22:24 [nigel]
Pierre: That works.
09:22:39 [Zakim]
Zakim has joined #tt
09:22:56 [nigel]
.. You don't need a member submission for that. Deciding on the scope early is a good idea.
09:22:58 [nigel]
Andreas: Yes
09:23:06 [nigel]
Pierre: Both make sense. Picking one is going to be really key.
09:23:44 [nigel]
Nigel: I think I hear consensus that some kind of TTWG technical report that addresses
09:23:58 [nigel]
.. the live contribution use case is worthwhile.
09:24:05 [nigel]
Glenn: Requirements would be useful to set the scope.
09:24:18 [nigel]
Pierre: Yes, a requirements document would be helpful.
09:24:35 [nigel]
Glenn: In general we should have requirements documents before new technical specifications.
09:24:41 [nigel]
.. I make a motion to require that.
09:25:01 [nigel]
Andreas: I propose a joint meeting with EBU group to discuss this. We have January in Munich
09:25:31 [nigel]
.. in mind. We wanted to bring this up and see what the availability of members.
09:25:42 [nigel]
Pierre: Feb 1 in Geneva would work for me.
09:25:46 [nigel]
Andreas: That is good.
09:26:29 [nigel]
Pierre: Specifically the morning of Feb 1!
09:26:43 [nigel]
Andreas: Propose 31st and 1st.
09:27:07 [nigel]
Pierre: I'm busy Friday 1st in the afternoon but the joint meeting could be just in the morning.
09:27:11 [nigel]
.. We don't need more than 3 hours.
09:27:30 [nigel]
Glenn: If we're having a face to face meeting it should be at least 2 days, if it is an official
09:27:34 [nigel]
.. WG face to face meeting.
09:27:47 [nigel]
Pierre: I think we are just proposing a joint TTWG - EBU meeting.
09:28:05 [nigel]
Glenn: That would make it a TTWG f2f, I can't justify a journey to Geneva for half a day.
09:28:39 [nigel]
Andreas: If we make a one and a half day meeting, on Thursday and Friday.
09:28:44 [nigel]
Glenn: I'm available on Saturday too.
09:28:56 [nigel]
Pierre: I'd rather not, my preference would be 30th and 31st and part of the 1st.
09:29:10 [nigel]
Andreas: It would be good anyway to have the EBU and TTWG members in a room together.
09:29:54 [nigel]
Pierre: We can do it during PTS, why not?
09:30:00 [nigel]
Andreas: We need to ask Frans and EBU.
09:30:30 [nigel]
.. I will ask Frans.
09:31:54 [nigel]
Nigel: Thanks, summarising the discussion:
09:32:11 [nigel]
.. * A technical report on live subtitle contribution is a good idea
09:32:18 [nigel]
.. * We need requirements for that
09:32:32 [nigel]
.. * We will investigate a joint meeting with EBU at end of Jan/beginning of Feb
09:33:04 [nigel]
.. Thank you.
09:33:13 [nigel]
Pierre: Thanks for bringing this up.
09:33:22 [nigel]
.. At some point we will have a technical discussion about the details, based on the
09:33:32 [nigel]
.. requirements, which will be crafted hopefully prior to that meeting, and that would be
09:33:40 [nigel]
.. a good time to have a technical discussion.
09:33:51 [glenn]
glenn has joined #tt
09:34:27 [nigel]
Glenn: Does the current Charter cover this work?
09:35:20 [nigel]
Nigel: The requirements document would be a Note so that would certainly be covered.
09:36:26 [nigel]
.. We don't have a specific deliverable for a Recommendation listed at present, so that
09:36:36 [nigel]
.. may be something that we should consider for a Charter revision.
09:36:56 [nigel]
.. By the way, if we proceed with David Singer's proposal from yesterday, that could be a
09:37:10 [nigel]
.. good moment to revise the Charter in any case, since the WebVTT Rec deliverable would
09:37:14 [nigel]
.. have to be pulled from the Scope.
09:38:01 [nigel]
.. For example we could target a Charter revision in May 2019 for another 2 years, pulling
09:38:09 [nigel]
.. the end date to 2021.
09:38:19 [nigel]
Glenn: 2023 will be the 20th anniversary of this WG.
09:39:47 [nigel]
Andreas: Noting that there are observers here who might be interested in this topic, if we
09:40:00 [nigel]
.. proceed with this work we should make it possible for new members to join our meetings.
09:41:37 [nigel]
Nigel: As Chair, I would like to know if there are any potential members especially in
09:41:52 [nigel]
.. different time zones and to be flexible about how we meet to allow them to participate.
09:42:15 [nigel]
Andreas: I also meant that it should be possible for non-members of TTWG to participate
09:42:20 [nigel]
.. in the discussion.
09:43:07 [nigel]
Nigel: For a non-Rec track requirements document with no IPR, that is fine of course.
09:44:07 [nigel]
.. To clear IPR rules when we get to a Rec track document obviously contributors do need
09:44:11 [nigel]
.. to be WG members, effectively.
09:44:29 [nigel]
Glenn: If we publish a Rec track document that is based in large part on another spec
09:44:39 [nigel]
.. outside of W3C then that may be precedent-setting.
09:44:43 [nigel]
Pierre: Like IMSC?
09:44:51 [nigel]
Nigel: It's not precedent setting.
09:45:01 [nigel]
Pierre: It's the same, it's based on TTML.
09:45:06 [nigel]
Nigel: I agree.
09:45:21 [nigel]
Pierre: From what I have read it's a how-to-interpret TTML document crafted in a particular way.
09:45:25 [nigel]
Glenn: That's reasonable.
09:46:30 [nigel]
Topic: AC Review feedback
09:48:50 [nigel]
Nigel: Reviews AC feedback. We don't have any comments to respond to.
09:51:28 [nigel]
.. We have a reasonable number of responses now, some more would be good.
09:52:13 [nigel]
Topic: TTML1 3rd Edition Rec CfC
09:52:29 [nigel]
Nigel: I realised that in my CfC for publishing the TTML1 3rd Ed Recommendation, I did not
09:52:41 [nigel]
.. include any consideration of superseding 2nd Edition. I don't think we need to do that
09:52:58 [nigel]
.. for TTML2 or IMSC 1.1, because the previous Recs still stand, i.e. TTML1 3rd Ed and IMSC 1.0.1.
09:53:36 [nigel]
Nigel: Can I make it a condition of the CfC that we supersede TTML1 2nd Ed when we
09:53:40 [nigel]
.. publish TTML1 3rd Ed.
09:53:45 [nigel]
Glenn: It would be inconsistent not to.
09:54:03 [nigel]
Pierre: Yes, supersede not obsolete.
09:54:14 [nigel]
.. In the fullness of time we should probably make an Edited Recommendation of
09:54:23 [nigel]
.. IMSC 1.0.1 to point to TTML1 3rd Edition too.
09:54:38 [nigel]
Andreas: Yes, superseding is okay.
09:54:47 [nigel]
Nigel: Thank you, that's a decision.
09:55:15 [nigel]
RESOLUTION: As part of the request to publish TTML1 3rd Ed as a Recommendation we will supersede TTML1 2nd Ed.
10:01:13 [nigel]
rrsagent, make minutes
10:01:13 [RRSAgent]
I have made the request to generate nigel
10:02:46 [nigel]
Nigel: We'll break for lunch now, back at 1300.
10:14:07 [mdjp]
mdjp has joined #tt
10:30:12 [fujisawa]
fujisawa has joined #tt
10:42:12 [fujisawa]
fujisawa has joined #tt
11:04:10 [MasayaIkeo]
MasayaIkeo has joined #tt
11:07:22 [atai]
atai has joined #tt
11:07:49 [nigel]
nigel has joined #tt
11:10:54 [nigel]
Topic: Future Requirements
11:11:06 [nigel]
Nigel: Since the break, we have a new observer and a new attendee:
11:11:40 [nigel]
Vladimir: Vladimir Levantovsky, Monotype, AC Rep, Chair of Web Fonts WG (awaiting re-charter)
11:11:53 [nigel]
.. I have a very keen interest in anything relating to text matters, including composition,
11:12:01 [nigel]
.. rendering, fonts and anything else you can imagine related to that.
11:12:43 [fujisawa]
fujisawa has joined #tt
11:12:57 [Yam_ACCESS]
Yam_ACCESS has joined #tt
11:13:07 [nigel]
mdjp: Matt Paradis, BBC, Chair of the Web Audio WG, and I run an accessibility and interactive
11:13:15 [nigel]
.. work stream for BBC R&D, which is where my interest in this group lies.
11:13:22 [nigel]
Nigel: Thank you, welcome.
11:13:46 [glenn]
glenn has joined #tt
11:13:56 [nigel]
s/Nigel: Thank you, welcome./
11:14:11 [nigel]
Peter: I'm Peter tho Pesch, from IRT. I'm working on a project to do with accessibility of
11:14:20 [nigel]
.. 360 and AR environments, particularly subtitles.
11:15:23 [nigel]
Nigel: Thank you, welcome.
11:16:05 [nigel]
.. Can I first get a very quick list of the new requirements areas that we want to cover in
11:16:06 [Peter__IRT_]
Peter__IRT_ has joined #tt
11:16:08 [nigel]
.. this conversation?
11:16:19 [nigel]
.. I already have 360º/AR/VR requirements.
11:16:39 [Vlad]
Vlad has joined #tt
11:16:44 [nigel]
.. This morning we covered live subtitle use cases so we don't need to duplicate that work.
11:16:45 [Vlad]
11:17:00 [nigel]
Present+ Vladimir, Peter
11:17:19 [nigel]
Nigel: I need to present some styling attributes for consideration, actually a bigger question
11:17:32 [nigel]
.. about bringing in arbitrary CSS and how we might go about doing that.
11:17:50 [nigel]
Andreas: I recently came across a requirement for a TTML documents container element.
11:18:12 [nigel]
Topic: New requirements: 360º/AR/VR
11:18:56 [nigel]
Andreas: Just to start on this, yesterday we had at the Media and Entertainment IG a
11:19:10 [nigel]
.. brief session where I showed some of the results of the work Peter has been doing.
11:19:19 [nigel]
.. We did not get into the detail, I just showed the videos and we agreed there is a use
11:19:30 [nigel]
.. case that needs to be solved, and there is not complete agreement, or it is not clear yet
11:19:44 [nigel]
.. where it should be solved. The M&E IG action was to organise a telco where we get the
11:19:57 [nigel]
.. necessary people from different groups together, discuss the problem scenario and then
11:20:02 [nigel]
.. work out where the work will be done.
11:20:16 [nigel]
.. Yesterday, because I walked through the different examples, I would like to repeat this
11:20:28 [nigel]
.. with Peter's comments because he has the necessary input.
11:20:37 [ericc]
ericc has joined #tt
11:20:39 [nigel]
.. Because Vladimir is working on a similar topic and yesterday brought up some additional
11:20:50 [nigel]
.. issues we may want to make a list of all the things that could be in scope of the TTWG.
11:21:21 [nigel]
Nigel: Just to note, our Charter includes in the Scope: "Investigate caption format requirements for 360 Degree, AR and VR video content."
11:21:51 [nigel]
Vladimir: And "caption" doesn't necessarily mean subtitles, it could be any text label that
11:21:57 [nigel]
.. is part of the content?
11:22:06 [nigel]
Glenn: We don't distinguish between subtitle and caption any more!
11:22:14 [nigel]
Vladimir: Would text label be considered in scope?
11:22:17 [nigel]
Glenn: Why not?
11:22:28 [nigel]
Andreas: The group name is Timed Text, which is very generic and doesn't say what it is
11:22:39 [nigel]
.. used for. For general matters also there is the CSS group.
11:22:53 [nigel]
Vladimir: I understand we will not cover all the presentation cases.
11:23:10 [nigel]
.. For example when you're in a 360º environment the text will be defined by timed text,
11:23:17 [nigel]
.. but the composition might be defined by CSS.
11:23:27 [nigel]
Nigel: Consider this in scope.
11:24:23 [nigel]
Andreas: [shows examples]
11:24:39 [nigel]
Peter: I will start here at this slide. Yesterday you showed already a little bit of the scope.
11:24:51 [nigel]
.. I often use this image because for me it was the easiest way to picture the coordinate system
11:24:55 [nigel]
.. we are using.
11:25:07 [nigel]
.. [world map, equirectangular projection]
11:25:24 [nigel]
.. You also know how this would map onto a sphere. This is a common way to represent
11:25:40 [nigel]
.. 360º videos, using this map and wrapping it round a sphere, putting the viewer at the
11:25:52 [nigel]
.. centre looking out (the other way from the way you see a globe normally).
11:26:00 [fujisawa]
fujisawa has joined #tt
11:26:12 [nigel]
.. Within the project I am working on, we are looking into ways of adding accessibility
11:26:24 [nigel]
.. services to VR, focusing on 360º videos right now.
11:26:35 [nigel]
.. There are some challenges, maybe we start with the videos to show you some of the
11:26:40 [nigel]
.. thoughts we had on this.
11:26:59 [nigel]
.. [always visible] This is the simplest mode, where the subtitles are always shown in the
11:27:21 [nigel]
.. viewport where the viewer is looking.
11:27:35 [nigel]
.. This is a basic implementation, you can see the subtitle text always sticks in one position.
11:27:50 [nigel]
.. In this example the text is aligned to the viewport not to the video.
11:28:20 [nigel]
.. [example with arrow pointing at the speaker]
11:28:35 [nigel]
.. Here if the speaker is off screen an arrow points to the left or right to show where the
11:28:45 [nigel]
.. speaker is located. It disappears when the speaker is in the field of view.
11:28:53 [nigel]
.. It's a small help for people to find where the action is.
11:29:05 [nigel]
.. The basic presentation mode is the same.
11:29:20 [nigel]
.. [fixed positioned] This is a completely different approach.
11:29:33 [nigel]
.. The subtitle is now fixed to the video not the viewport, like a burned in subtitle. The way
11:29:48 [nigel]
.. it is shown here, I don't know where this is used in practice, but there is an example
11:30:05 [nigel]
.. where the subtitle text is burned into the video at three different positions and fixed there.
11:30:11 [nigel]
.. [Formats]
11:30:19 [nigel]
.. A quick overview of how we implemented this.
11:30:31 [nigel]
.. IMSC, DASH, h.264 video.
11:30:44 [nigel]
.. Custom extensions to IMSC for providing the information we needed.
11:31:14 [nigel]
.. In this example, imac:equirectangularLong and imac:equirectangularlat are specified on the p element.
11:31:27 [nigel]
.. They specify a direction in the coordinate system, not really a position. You could specify
11:31:41 [nigel]
.. a vector and where the vector hits the sphere, that is where the subtitle is located.
11:31:47 [nigel]
.. This is used for the different implementations.
11:31:55 [nigel]
.. This is the current status.
11:32:07 [nigel]
.. Future thoughts: subtitles with two lines in each subtitle, belonging to different speakers
11:32:22 [nigel]
.. at different positions, so different angles for each speaker. We could add the attributes
11:32:31 [nigel]
.. at the span level but we did not do that yet.
11:32:46 [nigel]
.. Also what information the author can add to indicate the suitable rendering style.
11:33:10 [nigel]
Andreas: That's better than what I said yesterday! And it doesn't contradict it.
11:33:20 [nigel]
.. Yesterday there was the generic question where should this gap be addressed.
11:33:33 [nigel]
.. It was clear that TTWG comes into this. I think it's worthwhile first discussing if this kind
11:33:44 [nigel]
.. of use case falls in scope, and if these two attributes would be something that could
11:33:54 [nigel]
.. be added to TTML and IMSC, and what additional features are needed.
11:34:00 [nigel]
q+ to ask about distance
11:34:20 [glenn]
11:34:37 [nigel]
q+ to ask about other presentation models
11:34:41 [nigel]
ack glenn
11:34:58 [nigel]
Glenn: Those are very long property names, and they embed a particular projection semantic.
11:35:10 [nigel]
.. If they were to be put into TTML I would probably prefer shorter names as well as
11:35:22 [nigel]
.. extracting the projection method to a separate parameter for the document level.
11:35:38 [nigel]
q+ to ask about doing the projection based on a rectangular region
11:36:07 [nigel]
Glenn: As far as potential requirements, I think this is good and we should consider doing something in a standard.
11:36:22 [nigel]
.. We would have to define in the spec the transformation from the spherical coordinate
11:36:50 [nigel]
.. space to the projection coordinate space, for different projections, e.g. a projection method parameter.
11:37:24 [nigel]
ack n
11:37:24 [Zakim]
nigel, you wanted to ask about distance and to ask about other presentation models and to ask about doing the projection based on a rectangular region
11:37:51 [nigel]
Nigel: Why not use a 2d coordinate like for the video image and then project the text in
11:37:59 [nigel]
.. the same way as the video, rather than including the coordinates?
11:38:16 [nigel]
Peter: We thought about that. We have an additional mapping step. One way would be to
11:38:28 [nigel]
.. base the IMSC file on the 2D texture and then use the mapping mechanism that is
11:38:39 [nigel]
.. defined by the standard for mapping the video, also for the subtitle file, or to define
11:38:50 [nigel]
.. information directly in the IMSC in the target coordinate system.
11:39:00 [nigel]
.. We used this approach here because it is a lot easier to implement. This is the
11:39:11 [nigel]
.. rendering coordinate system and it is easy to map the video texture on a sphere in the
11:39:28 [nigel]
.. framework we are using. Then it is a lot easier to define the coordinates directly.
11:39:38 [nigel]
Glenn: Right now the x and y coordinate space in TTML is cartesian based and we have a
11:39:49 [nigel]
.. great deal of semantics, for example the extent of a region, is defined in x and y
11:40:05 [nigel]
.. coordinate space. You could use a reverse transformation as long as you have the
11:40:18 [nigel]
.. central meridian and standard parallels for doing a reverse projection to the
11:40:33 [nigel]
.. equirectangular form. I think we should be hesitant to express coordinates in a
11:40:44 [nigel]
.. coordinate space that is not based on our assumed cartesian space. I would rather do
11:40:58 [nigel]
.. a reverse transformation, specify x and y and map to spherical coordinate space.
11:41:11 [nigel]
Vladimir: A question. Everything so far seems to be related to flat 2D projections. How would
11:41:23 [nigel]
.. that apply to a stereoscopic environment.
11:41:37 [nigel]
Nigel: That was one of my questions - how do you specify depth?
11:41:49 [nigel]
Vladimir: You can break the user perception by getting it wront.
11:41:54 [nigel]
11:42:21 [nigel]
Nigel: We have disparity already but I don't know how disparity fits with the 3d coordinate system.
11:42:36 [nigel]
Peter: We also looked at MPEG OMAF (omnidirectional media application format) and the
11:42:47 [nigel]
.. draft describes how to add subtitles to the 3d space, and it supports WebVTT and IMSC
11:42:59 [nigel]
.. subtitles, and the IMSC subtitles are added in a way where the MPEG scope provides a
11:43:11 [nigel]
.. rendering plane for the IMSC to be rendered onto. The information in the IMSC document
11:43:24 [nigel]
.. is included in the OMAF format. There's an additional metadata track that contains those
11:43:36 [nigel]
.. information and that handles the information in the way MPEG does it. There is a box,
11:43:53 [nigel]
.. for regions, and for points in their coordinate system. You basically get a rectangular
11:43:58 [nigel]
.. plane for rendering your subtitles onto.
11:44:11 [nigel]
.. It also includes depth information for stereoscopic content.
11:44:42 [nigel]
Nigel: If there's depth information in the video then there must be depth in the subtitles,
11:44:47 [nigel]
.. how do those two get aligned?
11:45:02 [nigel]
Peter: I didn't fully look into this, but the standard suggests a default depth and radius
11:45:12 [nigel]
.. for the video sphere, and according to this you can either add depth information relating
11:45:25 [nigel]
.. to radius or directly add disparity information. The disparity information is not connected
11:45:37 [nigel]
.. to the video because it is connected to the presentation of the stereoscopic image, and
11:45:52 [nigel]
.. you would need to provide a left eye and right eye video stream.
11:46:20 [nigel]
11:46:37 [nigel]
Andreas: I want to point to Vladimir and ask: yesterday you brought up some additional
11:46:46 [nigel]
.. things. Apart from positioning, what other things may be useful or needed?
11:47:03 [MasayaIkeo]
MasayaIkeo has joined #tt
11:47:04 [nigel]
Vladimir: Yesterday I mentioned, speculatively, without a specific application in mind,
11:47:36 [nigel]
.. text objects need some kind of perspective transform to be applied.
11:48:14 [nigel]
.. How much detail we go into depends on how the responsibilities of text transform are
11:48:19 [nigel]
.. split between different parts.
11:48:29 [nigel]
Andreas: I wondered if CSS WG are working on the same thing, or another WG.
11:48:38 [nigel]
Present+ Philippe
11:48:53 [nigel]
Andreas: I think positioning of arbitrary HTML or whatever in this space could be in the long
11:49:09 [nigel]
.. run in the requirements. I don't want to contradict here what is being done in other groups.
11:49:20 [nigel]
Vladimir: I haven't heard anything about CSS considering 3D layout issues.
11:50:06 [nigel]
Philippe: The Immersive Web WG was created last month.
11:50:12 [nigel]
Andreas: I spoke with Chris Wilson yesterday.
11:50:18 [nigel]
Philiipe: He's one of the Chairs.
11:50:32 [nigel]
Andreas: I asked if we could present this use case tomorrow, he thinks it's not the right
11:50:50 [nigel]
.. moment, and prefers that it gets discussed in the WebXR CG, which has a repository
11:51:12 [nigel]
.. for requirements. If we open a requirement then we should open it there.
11:51:24 [nigel]
Philippe: We should ask the APA WG which is a coordination group for accessibility too,
11:51:37 [nigel]
.. you should ask Janina. She might well say it came up on their radar. I don't think they
11:51:41 [nigel]
.. have done any work on it.
11:51:59 [nigel]
Andreas: In this project we are also discussing user interfaces and this is definitely an
11:52:11 [nigel]
.. issue for the APA WG, UIs for navigation and control of access services.
11:52:22 [nigel]
Philippe: It's not just UI!
11:52:31 [nigel]
Andreas: OK.
11:52:42 [nigel]
Philippe: We don't have an accessibility group for the 3d space right now but that is where
11:52:46 [nigel]
.. the discussion should begin.
11:53:14 [nigel]
Vladimir: The Virtual Reality Industry Forum is another one outside W3C. We are still in the
11:53:29 [nigel]
.. exploration stage. We know what needs to happen to do what needs to be done in the
11:53:47 [nigel]
.. web, for example what to do with web fonts.
11:53:59 [nigel]
.. [i.e. web fonts might need some work]
11:54:09 [nigel]
Andreas: That group could point to something in W3C?
11:54:20 [nigel]
Vladimir: Yes, it would be a huge help to point to something from W3C.
11:54:52 [nigel]
Peter: There's one thought I wanted to add. When we look at the scope of MPEG OMAF,
11:55:04 [nigel]
.. keep in mind it is a distribution format, and it specifies how to bring the content to the
11:55:14 [nigel]
.. consumer but when you look at the complete chain the content will probably not be
11:55:30 [nigel]
.. described in OMAF. The subtitle workflow - it makes sense all the subtitle information is
11:55:48 [nigel]
.. kept in one place. You can look at it in two ways - either the positional description being
11:56:02 [nigel]
.. like a styling attribute or a kind of metadata to transport the information to the MPEG
11:56:14 [nigel]
.. format to distribute it to the user. Maybe there are two different use cases. One to
11:56:26 [nigel]
.. describe subtitles in a 3D space, something like an extended IMSC, or you could say
11:56:37 [nigel]
.. we need additional metadata, just tunnel this information to the point where the complete
11:56:43 [nigel]
.. format is mapped to a 3D space.
11:57:12 [nigel]
Nigel: Question: Do you need to describe the speaker position, the text position, or both?
11:57:25 [nigel]
Peter: That's a very good question. At the moment we are just pointing at the centre of the
11:57:37 [nigel]
.. speaker with no height information. We don't differentiate the speaker position or the
11:57:52 [nigel]
.. text position. They might be different.
11:58:32 [nigel]
Nigel: A follow-on question: what user information do have about preferences? Which of
11:58:44 [atai]
11:58:46 [nigel]
.. these do people want to use, one in particular or different people prefer different ones?
11:59:01 [nigel]
Peter: It's too early to say, research is ongoing. There are different results from different
11:59:16 [nigel]
.. tests pointing in different directions. For example a university in Munich found that half
11:59:32 [nigel]
.. of the test users preferred fixed position, and half didn't like it. It has the advantage
11:59:45 [nigel]
.. that it is more comfortable to view and induces less sickness but you can miss the
12:00:01 [nigel]
.. subtitle if you are not looking the right way. We are still looking to find the best way.
12:00:03 [nigel]
ack a
12:00:19 [nigel]
Andreas: How does VR-IF Forum relate to MPEG OMAF?
12:00:37 [nigel]
Vladimir: I think they have a liaison or they are just the same members. I doubt there is a
12:00:45 [nigel]
.. direct official relationship between the two.
12:01:03 [nigel]
.. VR-IF doesn't specify anything but produces usage guidelines. It's a different level, not
12:01:06 [nigel]
.. technical specifications.
12:01:20 [nigel]
Andreas: The other question is regarding font technology. Recently I have seen a lot of
12:01:35 [nigel]
.. advancement of the use of variable fonts on the web, with one font file with a large number
12:01:51 [nigel]
.. of font faces you could use. From the discussion I've heard this 3D space presents a
12:02:04 [nigel]
.. different kind of graphical challenge, and I see good application of variable fonts in this
12:02:08 [nigel]
.. space which I think should be explored.
12:02:13 [nigel]
Vladimir: I absolutely agree.
12:02:24 [nigel]
.. The reality is when you rely on a particular font feature to be available it would be
12:02:38 [nigel]
.. too optimistic to rely on the font that happens to be resident on the user's device.
12:02:52 [nigel]
.. When you rely on a specific font feature you're best/only bet is to serve the font to the
12:02:57 [nigel]
.. user so you know the font is present.
12:03:12 [nigel]
.. Same with variable fonts, which are in the early stages of deployment. If you want to use
12:03:17 [nigel]
.. them then you need to provide the font.
12:03:36 [nigel]
.. In VR-IF nothing is taken for granted, and if a particular font is needed, for feature or
12:03:55 [nigel]
.. language support, then that font has to be provided. On the web the font can be downloaded,
12:04:02 [nigel]
.. in ISOBMFF there is a way to provide a font.
12:04:17 [nigel]
Glenn: TTML2 supports font embedding now either directly in the TTML document or by
12:04:29 [nigel]
.. URL reference to the environment somewhere which in the context of ISOBMFF could be
12:04:34 [nigel]
.. part of the font carousel that's available.
12:04:39 [nigel]
Andreas: Is this in IMSC 1.1?
12:05:40 [nigel]
Nigel: I don't think so.
12:06:09 [nigel]
.. [confirms this by looking at the spec]
12:06:21 [nigel]
Andreas: TTML2 has a wide feature, IMSC is a subset that doesn't support this. At the
12:06:32 [nigel]
.. bottom line there should at least be a mechanism for the content provider to provide
12:06:33 [nigel]
.. the font.
12:06:48 [nigel]
Vladimir: Absolutely. If you expect that variable fonts are useful in this environment then
12:06:49 [cpn]
cpn has joined #tt
12:06:53 [nigel]
.. you have to provide them.
12:07:06 [nigel]
Andreas: As a proposal for the next steps, would it be a strategy to first try to fix the
12:07:15 [nigel]
.. requirements and describe the use cases we are trying to solve?
12:07:36 [nigel]
.. If this is ready then we can schedule the Web Media & Entertainment call on the IG and
12:07:39 [nigel]
.. discuss it.
12:07:59 [nigel]
Nigel: Sounds good. Are there other members than IRT interested in this?
12:08:07 [nigel]
Vladimir: I am interested, I am learning more than I can contribute.
12:10:38 [nigel]
Observer: Can TTML associate a piece of timed text with a point in space where the sound originated from?
12:10:49 [nigel]
Nigel: I think there is no standard way to do that now, no.
12:11:03 [nigel]
Vladimir: You're suggesting two independent spatial references, one for a specific location
12:11:19 [nigel]
.. and the other for a location of the source so if we wanted to implement the arrows
12:11:28 [nigel]
.. solution we would know the location of the source?
12:11:35 [nigel]
Observer: yes, I'm just curious.
12:11:43 [nigel]
Nigel: I think that is for the requirements document to describe.
12:12:27 [nigel]
Nigel: Matt, do we have data for object based media pointing to where sound should be positioned in space?
12:12:44 [nigel]
Matt: We do have prototype metadata for azimuth, elevation and distance, but there's a long
12:13:00 [nigel]
.. step between that prototype form and something that could be broadcast.
12:13:06 [nigel]
Nigel: Does it inform the data modelling?
12:13:21 [nigel]
Matt: It does, elsewhere we look at graph data for object based productions, and this is
12:13:41 [nigel]
.. at a higher layer than something like the Audio Definition Model.
12:13:58 [nigel]
.. It gives a reference for speaker or events or "sounding objects".
12:14:19 [nigel]
Nigel: I would suggest we should use the same coordinate system for things we can see
12:14:45 [nigel]
.. and things we can hear. It could be an accessibility issue, to allow transformation between
12:14:52 [nigel]
.. visual and auditory information.
12:15:14 [nigel]
Matt: It's a fundamental to get the coordinate system right. For example in Web Audio WG
12:15:31 [nigel]
.. we had to decide whether azimuth goes clockwise or anti-clockwise. Standardising on
12:15:36 [nigel]
.. a common API is important.
12:15:51 [nigel]
Andreas: For gathering requirements, typically we would start to describe what we want
12:16:04 [nigel]
.. to solve, and then all these questions will come up. We also learned from this discussion
12:16:18 [nigel]
.. that a lot of things come to mind based on what has already been specified, which will
12:16:30 [nigel]
.. come up when the requirements are clear and we are moving to a solution.
12:16:41 [nigel]
.. Peter you said you are willing to put some work into the requirements?
12:16:46 [nigel]
Peter: Yes definitely.
12:17:02 [nigel]
Andreas: Vladimir also said you are interested. I can be involved but I'm not an expert in this.
12:17:06 [nigel]
.. I can be a link and help out.
12:17:21 [nigel]
.. That would be my proposed action that you two and anyone else who is interested tries
12:17:33 [nigel]
.. to work out these use cases, and directly post it on the GitHub repository.
12:17:37 [nigel]
Nigel: What GitHub repo?
12:17:55 [nigel]
Andreas: The XR CG has a repo for requirements or proposals, that was Chris Wilson's
12:18:06 [nigel]
.. proposal and it's a good start to get it out there for everyone to access.
12:18:18 [nigel]
Peter: OK, for my understanding what we provide first is the use cases and what we want
12:18:34 [nigel]
.. to do, and the question is does it involve links to existing standards?
12:18:41 [nigel]
.. What standards are there to help solve these issues?
12:18:50 [nigel]
.. What is within the scope of the TTML WG?
12:19:05 [nigel]
.. Or the other WGs.
12:19:15 [nigel]
Vladimir: At this point we should probably have a critical eye on the existing standards.
12:19:27 [nigel]
.. If the standard exists it doesn't mean it was complete, correct or designed with the same
12:19:41 [nigel]
.. use cases in mind. The existing standards may need to be amended to be useful.
12:19:54 [nigel]
.. There may be something missing, which is useful information for the folks who
12:20:06 [nigel]
.. developed those standards. For example just because OMAF exists, doesn't mean it is
12:20:19 [nigel]
.. capable of supporting all possible use cases. If we find one that is not supported they
12:20:23 [nigel]
.. would welcome the contribution.
12:20:25 [nigel]
Peter: +1
12:20:37 [nigel]
Andreas: What you say makes a lot of sense Vladimir. I would propose to systematically
12:20:49 [nigel]
.. separate this so first we have a green field of what the use case is to solve, and the
12:21:00 [nigel]
.. requirements, and open up the issue on GitHub, then immediately afterwards reply to
12:21:13 [nigel]
.. it and say "these standards address this already" and then the discussion starts.
12:21:27 [nigel]
Peter: Yes
12:22:18 [nigel]
rrsagent, make minutes
12:22:18 [RRSAgent]
I have made the request to generate nigel
12:23:52 [nigel]
Vladimir: I have to leave now, thank you.
12:24:00 [nigel]
Peter: I will leave too, thank you.
12:24:07 [nigel]
Philippe: [went some time ago]
12:24:12 [nigel]
Nigel: Thank you all.
12:24:58 [nigel]
Topic: TTML Documents Container
12:25:12 [nigel]
Andreas: Recently a European broadcaster asked me if TTML can have multiple tracks,
12:25:20 [nigel]
.. for example different languages per file.
12:25:31 [nigel]
.. I said no that's not how it is defined, you have one document per track.
12:25:47 [nigel]
.. For authoring and archiving they thought about one file system with all the representatinos
12:25:55 [nigel]
.. for the same content in one file. I said no not now.
12:26:10 [nigel]
.. Then I realised you can put the root element of each document in a parent container,
12:26:23 [nigel]
.. and get this with a separate "TTMLContainer" element whose children are tt elements.
12:26:25 [Yam_ACCESS]
12:26:33 [nigel]
12:26:51 [Yam_ACCESS]
12:26:53 [nigel]
Andreas: I wondered if this is a more generic use case where you want to specify something.
12:27:22 [nigel]
Nigel: One option available in TTML2 is to use the condition mechanism to extract just
12:27:38 [nigel]
.. the content for, say, a specific language, and put all the different content in a single TTML document.
12:27:43 [nigel]
.. That's an alternative to what you suggested.
12:28:01 [nigel]
.. Another is to use a different manifest format, like IMF etc to handle this kind of case.
12:28:17 [nigel]
Glenn: I would have answered "yes of course" and it's the responsibility of the application
12:28:30 [nigel]
.. that's using TTML to define how to use it. It's something external to the TTML file.
12:28:46 [nigel]
.. I would refocus the question on making that an application specific usage scenario.
12:29:00 [nigel]
.. Like if you want a PNG, JPEG and SVG version of a single image, there's no requirement
12:29:11 [nigel]
.. for each file to know about each other but the outside usage may have a manifest of
12:29:20 [nigel]
.. potential realisations of that resource.
12:29:37 [nigel]
.. This is like the semantics of URNs and URIs. URIs are abstract, and URNs more so, but they
12:29:51 [nigel]
.. map to one or more URL that realises the resource, and each URL might have a different
12:29:58 [nigel]
.. aspect like language and so forth.
12:30:24 [nigel]
Andreas: I know that we delegate this. What Nigel said is to pick something out of the file
12:30:39 [nigel]
.. but you want to store it without picking something. You don't want to say which one is
12:30:54 [nigel]
.. preferred. You could specify the condition for a default to be selected.
12:30:55 [nigel]
Nigel: True
12:31:09 [nigel]
Andreas: The other storage scenarios are too big. It depends on the overall system
12:31:23 [nigel]
.. environment if they use IMF or something else. I don't think it makes sense just to store
12:31:33 [nigel]
.. subtitles in IMF without the video.
12:32:18 [nigel]
Nigel: It begs the question why localise subtitles only and not other resources like audio,
12:32:30 [nigel]
.. and if you are localising audio, then it starts to make more sense to use something like IMF.
12:32:42 [nigel]
Andreas: You may have the problem that you want the different subtitle versions in one
12:32:53 [nigel]
.. file. The condition attribute is an interesting thought to check out. It is not in IMSC?
12:32:55 [nigel]
Pierre: No.
12:33:09 [nigel]
Andreas: The easiest one is just to have multiple TTML documents in one file. Then you
12:33:22 [nigel]
.. can easily access the complete document tree and switch easily between different documents.
12:33:26 [ericc]
ericc has joined #tt
12:33:39 [nigel]
.. Then from one big file you can generate easily a separate document just for one version
12:33:41 [nigel]
.. or language.
12:33:50 [nigel]
Glenn: I don't like it at all.
12:33:56 [nigel]
Nigel: Don't like what?
12:34:16 [nigel]
Glenn: Multiple TTML documents as children of a parent element. It raises all sorts of
12:34:25 [nigel]
.. questions about semantics, like do they all start at the same begin time.
12:34:42 [nigel]
.. It is more reasonable that applications of TTML should define their own way to manage
12:34:47 [nigel]
.. groups of TTML documents.
12:35:41 [nigel]
Nigel: That sounded contradictory - do you mean it's okay for an application but not for this group to do?
12:35:50 [nigel]
Glenn: Yes, for example you could just put them in a zip file.
12:35:56 [nigel]
Nigel: Yes and give each a language-specific filename.
12:36:12 [nigel]
Glenn: Right [cites an existing example of this kind of technique]
12:36:28 [nigel]
.. It seems to closely arranged to specific application requirements, for example what is
12:36:43 [nigel]
.. the criteria for semantically grouping? Right now we define three different root level
12:37:03 [nigel]
.. element types, actually four, that can appear in a TTML document: tt, ttp:profile, isd:sequence and isd:isd.
12:37:17 [nigel]
.. The isd:sequence is a bit like what you're suggesting except you're suggesting a group
12:37:19 [nigel]
.. not a sequene.
12:37:22 [nigel]
12:37:42 [nigel]
Andreas: The use case could be that you have one file and a player like VLC offers the choice
12:37:57 [nigel]
.. of languages, and the same file would work in other players too. Two broadcasters
12:38:13 [nigel]
.. mentioned this to me recently, and others before. The scenario exists, and operational
12:38:26 [nigel]
.. people are looking for something like that. They can come up with their own solution,
12:38:35 [nigel]
.. the question is if a common solution makes sense.
12:39:03 [nigel]
Glenn: In HTML there's something called a "web archive" that a lot of tools can work with,
12:39:15 [nigel]
.. which saves all the page's files together in some form.
12:39:32 [nigel]
.. I've never seen any proposal within W3C to define a standard container for a collection
12:39:43 [nigel]
.. of HTML files, or PNG files or whatever basic content format file is being defined.
12:39:59 [nigel]
Andreas: The video element can have multiple text track child elements.
12:41:02 [nigel]
Nigel: I would push back against this because I think that the use case of localisation
12:41:22 [nigel]
.. goes beyond just subtitles, and should include all media types as first class citizens,
12:41:39 [nigel]
.. audio, video and anything else. It's detrimental to be too specific.
12:42:01 [nigel]
Nigel: Thanks, it seems like we don't have consensus to develop a requirements document
12:42:07 [nigel]
.. for grouping TTML documents at this stage.
12:42:18 [nigel]
Topic: Additional styling
12:42:31 [nigel]
Nigel: I wanted to raise this because we have an interesting use case in the BBC that
12:42:45 [nigel]
.. TTML cannot currently handle, even though it seems like it should be able to.
12:43:56 [fujisawa]
fujisawa has joined #tt
12:49:50 [nigel]
Nigel: [demonstrates some internal pages showing TTML presentation of narrative
12:50:03 [nigel]
.. text captions in video styled with CSS, animations, borders, border gradients etc.]
12:50:29 [nigel]
.. At the moment the CSS properties we would need are specific borders, clip-path and
12:50:35 [nigel]
.. background linear gradients.
12:50:45 [nigel]
.. I'm much more worried about future CSS properties that would be needed though.
12:50:47 [fujisawa]
fujisawa has joined #tt
12:50:59 [nigel]
Glenn: There are a couple of problems. One is testing - if we have a generic pass-through
12:51:14 [nigel]
.. mechanism, like a "css" property, whose value is a CSS expression, what do you put in
12:51:36 [nigel]
.. your profile? Right now we don't have a notion of parameterised set of values.
12:52:05 [nigel]
Andreas: In general I like the idea to use CSS features before they enter TTML properly.
12:52:16 [nigel]
.. I don't know how exactly, but in general I would support figuring out how this could work.
12:52:20 [nigel]
Glenn: It is worth investigating.
12:52:34 [nigel]
Pierre: Since the alignment has been with CSS it is worth a longer discussion.
12:52:46 [nigel]
.. Just in names there's friction for some folks, even though the gap is reducing. I also
12:52:58 [nigel]
.. like the way it is clear you don't have to import all of CSS, which is a relief to others.
12:53:12 [nigel]
.. For a computer, mapping a TTML name to a CSS name is a no-op. Alignment between
12:53:20 [nigel]
.. TTML and CSS has served us well so we should continue doing it.
12:53:35 [nigel]
Glenn: It would make it easier to expose CSS properties without the expense of a TTML
12:53:44 [nigel]
.. style attribute. There may be a sacrifice of interoperability.
12:53:54 [nigel]
Andreas: This group would just define the mechanism and then it is the responsibility
12:54:01 [nigel]
.. of the application if it supports it or not.
12:54:09 [nigel]
Glenn: Then there's the profile mechanism issue.
12:54:18 [nigel]
Andreas: Just say nothing about it.
12:54:26 [nigel]
Andreas: [leaves]
12:54:30 [nigel]
Pierre: [leaves]
12:54:39 [nigel]
Nigel: Thank you both.
12:54:59 [nigel]
.. OK for this requirement, I think it is worth spending some time describing the
12:55:14 [nigel]
.. requirement more fully, which I will try to do. Obvious solutions to this kind of thing
12:55:30 [nigel]
.. include specifying CSS properties directly on content elements or style elements,
12:55:43 [nigel]
.. and allowing a class attribute to define CSS classes that apply to a content element.
12:56:01 [nigel]
.. I realise both of these could create clashes between TTML styling and CSS styling and
12:56:22 [nigel]
.. we would need some mechanism for resolving those clashes. Especially class styling
12:56:39 [nigel]
.. is very different to the applicative styling we have in TTML, since it goes the other way
12:56:55 [nigel]
.. in terms of traversal.
12:57:19 [nigel]
Glenn: Class is a shorthand for id, and we already have id.
12:57:23 [nigel]
Nigel: It's not a shorthand for id
12:57:37 [nigel]
Glenn: You can have a CSS stylesheet associated with a TTML document and have #id styles
12:57:52 [nigel]
.. that are associating elements in TTML with CSS. In that sense adding class is just a
12:57:58 [nigel]
.. shorthand for aggregating multiple ids into one group.
12:58:01 [nigel]
Nigel: That's true.
12:58:38 [nigel]
Glenn: At application level you could put a CSS stylesheet on one side.
12:58:48 [atai]
atai has joined #tt
12:58:50 [nigel]
.. There's a precedent here in WebVTT of applying a stylesheet on the outside, though it
12:59:02 [nigel]
.. it not defined clearly. Then it becomes a player dependent function whether it ingests
12:59:10 [nigel]
.. and uses the stylesheet during the formatting process.
12:59:26 [nigel]
.. Especially if you are doing a process where you're converting TTML to HTML/CSS.
12:59:38 [nigel]
.. I would be reluctant to buy into an approach that requires mapping to HTML and CSS.
12:59:52 [nigel]
.. Provided that we can have native implementations or things that don't map to HTML/CSS
13:00:10 [nigel]
.. and still use whatever we develop here that would be my mental model for acceptability.
13:00:40 [nigel]
Nigel: Just wondering about how big a problem space I'm opening up. If we map TTML
13:00:56 [nigel]
.. to SVG do we have to define how any classes or styles are tunnelled through?
13:01:08 [nigel]
Glenn: It could be done, the implementation would need to do some book-keeping as it
13:01:26 [nigel]
.. goes through the area mapping process, to get to the SVG elements that can be styled.
13:01:37 [nigel]
.. One TTML element can generate multiple areas and you can have multiple TTML elements
13:01:40 [nigel]
.. generating one area.
13:02:19 [nigel]
Nigel: In terms of spec work should we feel obliged to define the tunnelling into SVG?
13:02:24 [nigel]
Glenn: I don't think so.
13:02:39 [nigel]
.. We just need to be careful not to impose a restriction to a particular mapping format.
13:02:52 [nigel]
.. It should be possible to make a native implementation that doesn't use CSS or SVG.
13:03:04 [nigel]
.. In such a situation the native player would have to interpret the CSS and do what CSS
13:03:18 [nigel]
.. does in that circumstance. A lot of CSS semantics are based on the box model and there
13:03:41 [nigel]
.. may be some minor impedance mismatches between our area model and the CSS box
13:03:42 [nigel]
.. model.
13:03:55 [nigel]
Nigel: I take your word for that, but our model came from XSL-FO, which was at least once
13:04:07 [nigel]
.. aligned with CSS>
13:04:09 [nigel]
13:04:21 [nigel]
Glenn: For example CSS doesn't allow width or height to be specified on non-replaced
13:04:41 [nigel]
.. inline elements whereas we do allow that for ipd and bpd on a span, even if it does not
13:05:16 [nigel]
.. have display "inline-block". I just wanted to mention that we have taken various
13:05:30 [nigel]
.. decisions semantic-wise where if we just expose CSS into the mix we may have to deal
13:05:36 [nigel]
.. with incompatibilities that might arise.
13:05:49 [nigel]
.. One answer to the implementer is "do whatever makes sense" which is generally how
13:05:57 [nigel]
.. implementers operate anyway, but then you get interop issues.
13:06:09 [nigel]
Nigel: That's the point, to make an extensible model that allows a greater variety of CSS
13:06:20 [nigel]
.. styles to be applied in applications that can support them.
13:06:36 [nigel]
.. For example we could put all the "CSS tunnelling" semantics behind a feature designator.
13:07:22 [nigel]
Glenn: Yes. The general approach for CSS is that implementations ignore what they do not
13:07:30 [nigel]
.. recognise. There are no guarantees.
13:07:46 [nigel]
Nigel: Some implementations support @support queries, but older ones might not.
13:08:08 [nigel]
Nigel: I think we have consensus to work this up in terms of requirements and head towards
13:08:15 [nigel]
.. a solution in some future version of TTML.
13:08:49 [nigel]
rrsagent, make minutes
13:08:49 [RRSAgent]
I have made the request to generate nigel
13:09:52 [nigel]
Topic: Audio Profiles
13:10:06 [nigel]
s/Topic: Audio Profiles/
13:10:27 [nigel]
Topic: Audio Profiles
13:10:42 [nigel]
Nigel: I presented something here to the joint meeting with the Media and Entertainment IG
13:10:58 [nigel]
.. yesterday, and there's an Audio Description CG meeting on Thursday.
13:11:13 [nigel]
.. For this group's benefit, the idea is to create a profile of TTML2 which supports the
13:11:19 [nigel]
.. features needed for audio description.
13:11:53 [nigel]
-> Presentation to joint meeting
13:14:55 [nigel]
Nigel: [shows TTML2 feature list]
13:15:52 [nigel]
.. I've just been told that the BBC implementation is live on, but not quite working yet
13:16:08 [nigel]
-> BBC Adhere implementation
13:16:23 [nigel]
.. It has some build issues to fix.
13:16:37 [nigel]
.. My intent is that when the CG is settled on the profile we add it to the TTWG Charter
13:16:41 [nigel]
.. as a Rec track document.
13:17:13 [nigel]
Glenn: During the drive up to the implementation report you mentioned some challenges
13:17:27 [nigel]
.. and we made changes to some of the feature definitions - we removed embedded-audio
13:17:41 [nigel]
.. from the audio-description feature. Was that due to an implementation constraint?
13:18:00 [nigel]
Nigel: We made different changes. The embedded audio was one where I wasn't sure if
13:18:19 [nigel]
.. we would hit time limits. The other was text to speech in conjunction with web audio,
13:18:32 [nigel]
.. which is an API limitation that web speech output is not available as an input to web audio.
13:18:41 [nigel]
Glenn: Can that be rectified?
13:18:51 [nigel]
Matt: I had a response about this a couple of weeks ago. Due to licensing of some of the
13:19:06 [nigel]
.. recognisers and synthesisers in the Web Speech API they are not licensed for recording
13:19:19 [nigel]
.. so there was little enthusiasm for making an API call that would capture speech output
13:19:31 [nigel]
.. from the API. Of course there are other ways to do it, but making it a feature would
13:19:48 [nigel]
.. open it up to licensing issues.
13:20:01 [nigel]
Nigel: The Web Speech API never got towards Rec, it's a Note I think.
13:21:10 [nigel]
Glenn: Generally IPR isn't an issue for W3C specs.
13:21:19 [nigel]
Matt: It has multiple implementations but is still a CG report.
13:21:34 [nigel]
.. The "terms of service" for many voices allow use in real time but prohibit recording the
13:21:38 [ericc]
ericc has joined #tt
13:21:39 [nigel]
.. audio and saving it for later playback.
13:25:31 [nigel]
Nigel: If we can encourage that to get to resolution then we could use it for AD.
13:25:45 [nigel]
.. The other issue to note is that for embedded audio, there's a bit of a challenge
13:26:02 [nigel]
.. implementing clipBegin and clipEnd. For normal audio resources you can use media
13:26:33 [nigel]
.. fragments on URLs to make a time range request, but in our testing it didn't seem to
13:26:52 [nigel]
.. honour the end time always, just the begin time. But more seriously for embedded audio,
13:27:21 [nigel]
.. if you implement it as a data: url then those URL media fragments seem to be completely ignored.
13:27:46 [nigel]
Matt: Range requests have to be supported by the server I think. Most do, but it's not a given.
13:27:51 [nigel]
.. The data URL may not be supported at all.
13:28:09 [nigel]
.. The response has to have the accept-ranges header set.
13:28:26 [mdjp]
range requests
13:29:05 [nigel]
Nigel: I think this is a different thing. It's byte ranges.
13:29:28 [nigel]
-> Media Fragments URI
13:29:35 [nigel]
Nigel: That's what I meant.
13:31:05 [nigel]
.. It allows for a url#t=10,20 for example to give everything between 10 and 20s. In testing
13:31:11 [nigel]
.. that doesn't seem to work with data urls.
13:31:28 [nigel]
.. That's something that may need an explicit mention in a future edition of TTML2, for example.
13:32:32 [nigel]
.. While we're on future editions of TTML2, and audio, I hope to be able to define the
13:32:42 [nigel]
.. audio processing model more normatively than it is now.
13:33:06 [nigel]
Nigel: The Web Audio spec is in CR at the moment, isn't it?
13:33:25 [nigel]
Matt: Yes. Timeline to be discussed in the meeting on Thursday. No issues have been
13:33:35 [nigel]
.. raised, we're not aware of any problems. On a similar note I should say we're meeting
13:33:48 [nigel]
.. on Thursday and Friday, which conflicts with the AD CG but the main topic will be
13:33:59 [nigel]
.. use cases, requirements and features that have been omitted from v1 so if there's anything
13:34:13 [nigel]
.. around this work that would require Web Audio work to facilitate it now would be a good
13:34:19 [nigel]
.. time to provide them.
13:34:31 [nigel]
Nigel: Thanks for that, if any arise I will let you know!
13:35:51 [nigel]
Glenn: Back on the issue of speech, I had pointed out how in TTML we defined a special
13:36:03 [nigel]
.. resource URL for output of the speech processor, and how that was intended to be
13:36:19 [nigel]
.. potentially used as an input to the audio element, so you could say an audio element
13:36:35 [nigel]
.. is the speech resource instead of a pre-defined clip, and that would be useful for mix
13:36:41 [nigel]
.. and gain operations.
13:36:43 [ericc]
ericc has joined #tt
13:36:55 [nigel]
Nigel: It's unnecessary - we didn't need to use that in our implementation.
13:37:08 [nigel]
Glenn: The connection between the speech processor's output and the audio node
13:37:17 [nigel]
.. hierarchy does not exist.
13:37:22 [nigel]
Nigel: We take it as an implied one.
13:37:33 [nigel]
Glenn: That's an implementation choice that I didn't intend in the spec.
13:38:08 [nigel]
Nigel: That seems to be unnecessary pain - if you bother to put tta:speak in as anything other than none
13:38:44 [nigel]
.. then you obviously want to generate audio.
13:38:52 [nigel]
Glenn: You need it to be able to pan the speech output, for example.
13:38:57 [nigel]
Nigel: That's true, I didn't consider that.
13:40:29 [nigel]
.. You could posit an implied anonymous audio element if the span's tta:speak is not "none" and there is no explicit audio element child.
13:40:40 [nigel]
Glenn: That's a bit like putting origin and extent on a content element!
13:40:52 [nigel]
Nigel: I sort of see what you mean [scrunches eyes]
13:41:07 [nigel]
Glenn: In the definitions section I define a speech data resource.
13:43:19 [nigel]
Nigel: It doesn't seem clear what happens if tta:speak is not "none" and there is no
13:43:21 [nigel]
.. audio element child.
13:43:46 [nigel]
.. It is possible that we can tidy this up in a future edition.
13:44:00 [nigel]
Glenn: It could be improved - we could tie it to that binding mechanism more explicitly.
13:44:06 [nigel]
Nigel: +1
13:44:38 [nigel]
.. However I would like to see a syntactic shortcut that avoids the need to have an audio
13:45:58 [nigel]
.. element with a long string in it just for "mix this audio" when tta:speak is set, because
13:46:01 [nigel]
.. that's obvious.
13:48:59 [nigel]
Glenn: I notice that it is not possible to add audio as a child of body, in TTML2. Why not? I don't recall my logic there, if there was any.
13:49:12 [nigel]
Nigel: I think it's clear that there's a bucket of audio-related potential improvements that
13:49:29 [nigel]
.. are most likely to come out of work in the AD CG, which we should consider for a future
13:49:34 [nigel]
.. edition of TTML2.
14:01:59 [nigel]
Topic: Meeting close
14:02:46 [nigel]
Nigel: Thank you everyone, we've reached the end of our agenda for today.
14:03:02 [nigel]
.. We should take a moment to celebrate the success we've had in all the work we've done
14:03:12 [nigel]
.. on TTML and IMSC over the past few years!
14:03:35 [nigel]
.. Next week we have no weekly call, the week after I will send an agenda as usual.
14:03:37 [nigel]
.. [meeting adjourned]
14:03:42 [nigel]
rrsagent, make minutes
14:03:42 [RRSAgent]
I have made the request to generate nigel
14:06:06 [nigel]
14:07:55 [nigel]
s/Masaya Ikeo, NHK/Masaya Ikeo, NHK - Yam_ACCESS
14:24:28 [nigel]
rrsagent, make minutes
14:24:28 [RRSAgent]
I have made the request to generate nigel
14:53:05 [Zakim]
Zakim has left #tt
15:07:10 [nigel]
s/It seems to closely arranged to specific application requirements/It seems too closely aligned to specific application requirements
15:11:58 [atai]
atai has joined #tt
15:13:30 [nigel]
rrsagent, make minutes
15:13:30 [RRSAgent]
I have made the request to generate nigel
15:13:54 [nigel]
scribeOptions: -final -noEmbedDiagnostics
15:13:57 [nigel]
rrsagent, make minutes
15:13:57 [RRSAgent]
I have made the request to generate nigel
17:19:20 [github-bot]
github-bot has joined #tt