14:00:35 RRSAgent has joined #tt 14:00:35 logging to http://www.w3.org/2016/08/04-tt-irc 14:00:37 RRSAgent, make logs public 14:00:37 Zakim has joined #tt 14:00:39 Zakim, this will be TTML 14:00:39 ok, trackbot 14:00:40 Meeting: Timed Text Working Group Teleconference 14:00:40 Date: 04 August 2016 14:02:43 Present: Harold, Nigel, Pierre 14:02:45 Chair: Nigel 14:02:49 scribe: nigel 14:03:01 Regrets: Andreas, Frans 14:03:30 Present+ Glenn 14:03:50 Topic: This meeting 14:04:00 tmichel has joined #tt 14:04:02 gadams has joined #tt 14:04:12 nigel: Today we have some TTML topics to discuss and probably not much else... 14:04:35 tm has joined #tt 14:04:54 ... I have a non-update re TPAC. 14:05:18 ... There's been some work this week on TTML, with a new pull request and some wiki 14:05:26 ... discussion of time related matters. 14:05:40 ... I should also raise the topic of Horizontal Review for TTML. 14:06:20 nigel: Any other topics to discuss today, including AOB? 14:08:46 group: No other topics 14:08:52 Topic: TPAC 2016 14:08:55 action-475? 14:08:55 action-475 -- Nigel Megitt to Contact the chair of the web & tv ig to ask about schedule and joint meeting time. -- due 2016-07-28 -- OPEN 14:08:55 http://www.w3.org/AudioVideo/TT/tracker/actions/475 14:09:14 nigel: I did try to contact Yosuke of the Web & TV IG but he didn't yet reply. 14:10:30 tmichel: Yosuke is still around, I need to check the other chairs of the Web & TV IG. 14:10:36 tmichel: I'll send him a reminder. 14:10:38 nigel: Thanks! 14:11:12 tmichel: I'm trying to setup some kind of meeting for WebVTT to have it move forward at 14:11:21 ... least to process the wide review comments that have been on hold for the last year. 14:11:27 ... I hope by TPAC we can get an action plan. 14:12:49 glenn: I'm arriving on the Friday before the meeting starts so if anyone wants to get together 14:13:06 ... in advance to talk about timing or anything we could arrange that. 14:13:19 nigel: I'm arriving on the Sunday late afternoon, so would be available. 14:13:25 tmichel: I will arrive on Sunday evening. 14:13:34 pal: I'll arrive on Sunday evening too. 14:13:59 glenn: [suggests organising a meeting over dinner on the Sunday evening] 14:14:26 ... I'm staying at the Palacio de Governador. 14:14:31 nigel: I'm in the Mercure. 14:15:34 nigel: Sounds like a good idea - let's try to organise that offline. 14:15:45 Topic: TTML1 & TTML2 issues, actions, PRs, editorial actions etc 14:16:11 action-462? 14:16:11 action-462 -- Glenn Adams to Create issue on ttml2 to add "mapping from other versions and profiles of ttml" -- due 2016-04-28 -- OPEN 14:16:11 http://www.w3.org/AudioVideo/TT/tracker/actions/462 14:16:45 glenn: That can wait a while longer. 14:18:26 glenn: On the duplicate absolutize designators I have the input I need and can take that forward. 14:18:40 ... On the br on timeContainer the real reason it can be a timeContainer is because it can 14:19:02 ... have animation children. 14:19:25 nigel: I don't think that's the question - the PR just adds the BR element to the list. 14:19:54 glenn: I can go ahead and merge that PR too. 14:20:22 nigel: Great, is the next thing to talk about time? 14:20:43 glenn: Yeah... there's a lot there. In SMIL 3 ยง5.7.1 which covers terminology and concepts 14:20:52 ... in SMIL there's a very appropriate short statement. 14:21:07 Global time is defined relative to the common reference for all elements, the document root. This is sometimes also referred to as document time. 14:21:40 glenn: This is a key statement in my opinion in that it ties document time to the document 14:21:56 ... root, which in our case is the tt element, which SMIL calls global time, which is time within 14:22:21 ... the SMIL 3 context. I did a little historical research on TTML - if you go back to the 14:22:49 ... TTML1 LCWD and before, we had begin and end time on the tt element itself, and we moved 14:22:49 ... that between LC1 and LC2 over to the body element. And we altered some of the language 14:23:02 ... in the definition of tt around that time. It's actually referenced in some of my comments 14:23:06 ... in Nigel's walk-through. 14:23:38 nigel: I made https://github.com/w3c/ttml2/wiki/Nigel's-TTML-and-SMIL-walkthrough 14:26:53 nigel: Thanks Glenn for your comments. I think we're converging... 14:27:42 glenn: We didn't dive into this level of detail before. I think I agree that we're converging. 14:27:54 ... My take on it is that the things that I thought were potentially broken for example in 14:28:10 ... the current definition of document time and root temporal extent, I'm finding it's less 14:28:22 ... broken than I thought it was. The confusion may have arisen around the use of the term 14:28:35 ... implicit duration as opposed to active duration, in the text under the tt element. 14:32:44 pal: Do we really need to reference SMIL? Can we not define our own summary of timing semantics. 14:32:57 ... It seems confusing to reference SMIL when the timing semantics can be succinctly expressed 14:33:16 ... as in Nigel's summary. I don't think anyone will build a TTML implementation on a SMIL library. 14:33:42 glenn: I'm sympathetic to that. 14:36:03 glenn: Writing new text and excising SMIL references would be a fair bit of work. Also, we 14:36:14 ... may get it wrong and break something. On the other hand that may not be such a concern 14:36:30 ... given the complexity of interpreting SMIL, which may lead to broken implementations 14:36:44 ... in the first place. I'm not wedded to keeping the SMIL terms but it would take a fair bit of 14:36:47 ... editorial work. 14:37:02 pal: I'm somewhat encouraged by the fact that the model that Nigel proposed is pretty 14:37:09 ... intuitive and straightforward. 14:42:44 nigel: What I wrote is probably not algorithmically complete, but should have all the rules 14:42:51 ... in that allow the algorithms to be derived. 14:43:40 ... There is some discussion of SMIL in chrome, where there was a much argued deprecation notice. 14:43:50 ... Google seems to be reconsidering that. It's in the context of animating SVG. 14:44:26 ... We could non-normatively reference SMIL as the origin for the cut-down timing semantics. 14:44:33 pal: +1 to that. 14:44:52 glenn: This is also similar to the situation we have with style, and XSL-FO and CSS. I think that 14:45:02 ... may even be more complicated than timing, but both are certainly complex. 14:47:07 glenn: There was another attempt to do this by Sean, in our change documents. In his proposal 14:47:18 ... for mapping to HTML and CSS he had an extremely simplified timing resolution model, 14:47:25 ... which I decided at some point was inadequate. 14:47:45 http://www.w3.org/wiki/TTML/ChangeProposalIndex 14:48:36 glenn: Here's Sean's attempt to simplify the algorithm without referring to SMIL: https://github.com/w3c/ttml2/wiki/Nigel's-TTML-and-SMIL-walkthrough 14:49:15 ... It would be interesting to compare this attempt to yours. 14:49:16 nigel: I haven't looked at that for a very very long time! 14:50:55 https://github.com/skynav/ttt/blob/master/ttt-ttx/src/main/java/com/skynav/ttx/transformer/isd/TimingState.java 14:51:19 glenn: I pasted above the link to the main file in TTX that deals with timing state. 14:52:01 ... It has functions like resolveActive() etc so this was our attempt to try to implement the SMIL semantics. 14:52:09 regrets+ Mike 14:55:41 pal: I see the concepts of computing the active interval and positioning that active interval on an external timeline as being independent steps. 14:55:53 pal: It's like root container and layout. 14:56:02 glenn: That's right. They both have the concept of clipping. 14:56:05 nigel: +1 14:56:32 pal: Maybe we can first focus on unambiguously specifying what is the "effective" begin and end 14:56:44 ... of every element on the document's abstract timeline and secondly what happens when 14:56:50 ... you map it to that external context. 14:57:39 glenn: The notion of an active interval or duration in SMIL had to be different in SMIL because 14:57:51 ... of the notion of repeat and min and max attributes, so it may be possible to jettison the 14:57:55 ... concepts of active vs simple. 14:59:11 nigel: I think we do need to make sure that we unambiguously define which frames are 14:59:31 ... dropped in drop modes. Also of course when using a clock timebase the relationship between 14:59:46 ... document time and real time becomes somewhat more explicit. The two concepts can 14:59:51 ... still be treated orthogonally. 15:06:19 group: some discussion of smpte mode discontinuous and conversion to continuous times, and the reference time for dropMode being 0. 15:06:35 nigel: We're out of time for today. It feels like we're making some headway on the wiki so I 15:06:47 ... suggest we continue on there, and also each look at the other documents that have been 15:06:54 ... referenced here today. 15:06:58 glenn: Sounds good. 15:07:19 pal: When I can access a computer I'll send a summary to the reflector of my really dumb 15:07:27 ... mental model for how smpte discontinuous works. 15:07:42 nigel: Thanks all. [adjourns meeting] 15:07:45 rrsagent, generate minutes 15:07:45 I have made the request to generate http://www.w3.org/2016/08/04-tt-minutes.html nigel 15:12:41 s/Global time is defined/SMIL3: Global time is defined/ 15:13:30 s/I made/To explain: I looked through TTML2 and SMIL3 to explain how the timing works and documented it in 15:19:45 s/... dropped/nigel: dropped 15:21:35 s/... document time and real/nigel: document time and real 15:21:57 rrsagent, generate minutes 15:21:57 I have made the request to generate http://www.w3.org/2016/08/04-tt-minutes.html nigel 15:26:49 ScribeOptions: -final -noEmbedDiagnostics 15:26:50 rrsagent, generate minutes 15:26:50 I have made the request to generate http://www.w3.org/2016/08/04-tt-minutes.html nigel 16:29:18 Zakim has left #tt