- From: Nigel Megitt <nigel.megitt@bbc.co.uk>
- Date: Thu, 10 Nov 2022 17:30:35 +0000
- To: TTWG <public-tt@w3.org>
- Message-ID: <16B5005D-4294-482F-A9D4-1E75AA5BEEBE@bbc.co.uk>
Thanks all for attending today’s TTWG teleconference. Minutes can be found in HTML format at https://www.w3.org/2022/11/10-tt-minutes.html In text format: [1]W3C [1] https://www.w3.org/ Timed Text Working Group Teleconference 10 November 2022 [2]Previous meeting. [3]Agenda. [4]IRC log. [2] https://www.w3.org/2022/10/27-tt-minutes.html [3] https://github.com/w3c/ttwg/issues/232 [4] https://www.w3.org/2022/11/10-tt-irc Attendees Present Atsushi, Cyril, Gary, Nigel, Pierre Regrets - Chair Gary, Nigel Scribe nigel Contents 1. [5]This meeting 2. [6]Rechartering Formal Objection Council update 3. [7]IMSC-HRM 1. [8]Plan to reference IMSC-HRM from future revisions of IMSC? 2. [9]CR1 exit criteria w3c/imsc-hrm#56 4. [10]DAPT 5. [11]Meeting close Meeting minutes This meeting group: [discussion of zoom access, URLs, the ability to use W3C zoom] Atsushi: I will send the Chairs an email about W3C zoom Nigel: Thank you Nigel: Today we have DAPT, a couple of points on IMSC-HRM, and if there's a status update on the … charter FO Council, we can take that too. … Is there any other business? Pierre: On IMSC-HRM I would like to cover CR Exit criteria - I created a Pull Request. Nigel: OK, thank you group: [no other business] Rechartering Formal Objection Council update Nigel: Anything to report? Atsushi: I just know that the Council is set up and they're working to coordinate on the time of the meeting … so nothing further has happened. Nigel: Thank you. Any questions? IMSC-HRM Plan to reference IMSC-HRM from future revisions of IMSC? Nigel: This comes from a comment in w3c/imsc-hrm#51 where Pierre said he thought we <Github> [12]https://github.com/w3c/imsc-hrm/issues/51 : If referencing from IMSC, references will be circular [12] https://github.com/w3c/imsc-hrm/issues/51 Nigel: should not reference IMSC-HRM from IMSC. … First question: are you saying we should remove the normative requirement to meet IMSC-HRM from IMSC? Pierre: Yes, that's correct. It would remove that from conformance in future editions of IMSC. Nigel: The argument is that it's not used? Pierre: Two arguments. A) to avoid the circular reference. … B) It won't have a significant difference because organisations that want to enforce … the HRM have called it out separately. … I don't think it will cause an impact in practice. … We can always have a note in IMSC that points to IMSC-HRM, e.g. <atsushi> +1 for informative note to inform, consumer can choose to apply both or only imsc Pierre: saying "this spec does not impose any constraints on presentation complexity, here's where to find it". Nigel: This raises the question of if IMSC-HRM needs to be a Rec track document? Pierre: To the extent that other orgs would use it for conformance I think they would appreciate it being … a Rec track document. To a large extent it depends on those external organisations. … I know some that would be reluctant to reference a WG Note for instance. Nigel: And the positive reason for removing from IMSC - is it only to avoid the circular reference? Cyril: Why is it a problem to have circular references? Other specs do that a lot - almost every standard in ISO! Nigel: We've always tried to be clear about the chain of dependencies from spec to spec, and avoided … circular references. … That was my next question too, is this the only way to avoid circular references? Atsushi: I'm curious too - I believe this is something that humans can check, for circularity, … e.g. if A defines in terms of B and B is defined in terms of A. That can even be in one specification. … It cannot easily be detected automatically. Nigel: That's right, there are ways to deal with this. Also, can IMSC-HRM stand on its own, or can … it be used only for IMSC. Pierre: It's a constraint on IMSC, the dependency is pretty obvious that IMSC-HRM depends on IMSC. … For better or worse, for many implementations, renderers have implemented IMSC but not the HRM validation. Pierre: I think circular references are bad simply because they're circular. … I don't want this to be an obstacle. If there's a desire to have a circular reference I'm not going to … no-vote the document. … Imagine: circular refs are bad because if IMSC gets updated without updating IMSC-HRM, then you don't … go back to where you started if you follow the reference. Sometimes that's harmless, sometimes harmful. … Being serious about conformance. which some orgs are, then we would have a separate conformance … document. Nigel: That would be the IMSC spec though? Pierre: Not always. I'm simply advocating having IMSC-HRM reference IMSC, and have an undated … reference from IMSC to IMSC-HRM. … Maybe later we'll have a spec on readability complexity for Western European languages, as a separate spec. Nigel: I'd like two things to happen: … 1. We arrange it so that the decision about how to reference IMSC-HRM from IMSC is made separately, … which means: … 2. We word IMSC-HRM so that it can be referenced normatively from IMSC, if that's what we some time want. … An easy way to deal with this circular reference is to duplicate the definition. Pierre: That is an editorial nightmare - I'd object to that. Nigel: Is it though? Is it worse? Pierre: Yes, it causes work. Nigel: My argument is that a change to one doc doesn't then require a change to the other, because … the definition has document-level scope only. Pierre: I'd prefer circular references than defining the same term twice in two different specifications. … I've never seen that end well. Nigel: I'm thinking that carefully arranged circular references might be the best option here. … My original issue was that there should be no circular references _that cannot be resolved_, so if we … can check that, it should be fine. Pierre: I think the references are undated now, so I think it will work. Nigel: Let's say we make some tweak to a defined term in a future version of IMSC, can we make … it so that the reference to that term in IMSC-HRM is to the one for the version of IMSC that applies? Pierre: We should try to avoid doing that and if we do, we should do it very carefully. … One could argue that we should reference a particular version of IMSC. … Nowadays in practice people look at the latest version. … The responsibility would be on us, if we make a substantive change to a definition or something … depended upon in the spec, then we better warn people, it could be disruptive. … Like changing glyph buffer Gn to glyph back buffer is really editorial, but it we were to change … Presented Region that would have a negative impact and we might want to define a new term instead. Github: [13]https://github.com/w3c/imsc-hrm/issues/51 [13] https://github.com/w3c/imsc-hrm/issues/51 Pierre: Not to be philosophical, let's not make a new version of IMSC that's incompatible with an old one! … I've seen that in other specs. SUMMARY: Keep the references circular for the time being, and check that they can all be resolved successfully. Pierre: We can defer this until we revise IMSC to reference IMSC-HRM. Nigel: No, I want us to make sure we don't put something in IMSC-HRM that gives us a problem later. Pierre: I'm not aware of anything that gives us that problem right now. Nigel: That may well be the case. SUMMARY: Nigel to verify that the current text will not cause any issues. github-bot, end topic CR1 exit criteria w3c/imsc-hrm#56 <Github> [14]https://github.com/w3c/imsc-hrm/pull/56 : CR1 exit criteria [14] https://github.com/w3c/imsc-hrm/pull/56 github: [15]https://github.com/w3c/imsc-hrm/pull/56 [15] https://github.com/w3c/imsc-hrm/pull/56 Nigel: This is a draft PR, maybe that's why I did not notice it ahead of the call. Pierre: Walking through this. Nigel: [shares [16]https://github.com/w3c/imsc-hrm/pull/56/ files?short_path=37df7cf#diff-37df7cf5e1fb2c2cfdd1d6eed9ffb1dda a7070ffc160a1bf1aa717ecf60db1cc on screen] [16] https://github.com/w3c/imsc-hrm/pull/56/files?short_path=37df7cf#diff-37df7cf5e1fb2c2cfdd1d6eed9ffb1ddaa7070ffc160a1bf1aa717ecf60db1cc Pierre: I thought adding a MD doc was a good way to kick around ideas. … This lays out how we will demonstrate Implementation Experience. … The idea is that each IMSC document is accompanied by an assertion that says if it passes or fails. … The idea is that each document is tested against each implementation and we determine that it … meets the assertion. … Features at risk: it occurred to me that the current implementation of imsc-hrm does not support … image profile, because nobody has asked for it. Unless we can find actual image profile documents, … from people who use it at scale, we should just remove that feature from IMSC-HRM … Then there's a bunch of synthetic tests to test the boundaries and features of the HRM. … If we are happy with this structure, then I'll add more synthetic tests. … That's my proposal for exit criteria. … Atsushi asked if we want exit criteria to be different for each CR version. … In the past I have found that CR exit tests are not necessarily useful for the community, long term. … Right now the synthetic tests are just in a directory. Cyril: Two questions. … First, the collection of sample IMSC documents. … I'm wondering, e.g. for Netflix, how we can contribute them, for IP reasons. Pierre: Thanks for the offer! I would expect Netflix to run the implementation internally and just report … on the results, I would be satisfied with that. Cyril: Okay, that makes sense. … Second, do you have a list of features that you want to test? Pierre: Not yet. There are different ways the HRM can be exceeded, … maximum glyph buffer size, maximum rendering time. … You'd want a test for each of those. … There's also IPD, a maximum render time, to test. … We should also test failure on the first ISD of a sequence, because it's somewhat of a special case. … We should test the ideograms as having a different rendering rate from non-ideograms. … We should have test documentations that fail if the glyph buffer is not being used. … I am planning to clean up the tests for the implementation and make them available. Cyril: I'm wondering if there's a list of those features? Pierre: Yes, we could add a feature test column. Cyril: In other standard bodies we're working on having explicit references from the spec to the tests. … Tools like bikeshed or respec help, they can generate assert ids, which you add with special markup … in the spec text. Then you can use those in the naming of the tests. … Respec has a way to show you the tests, if you cross-reference them properly. … It may be worth investigating. Pierre: Absolutely, I'll look at that, thanks. Nigel: Elephant in the room - this approach is going to be dependent on the result of the FO Council. … I think we cannot finalise this approach until we have the FO Council outcome. Atsushi: Usually they have a single call to arrive at their conclusions, so we may hear something at the … end of this month, at least. Of course it make take time to generate the formal document to be published. … In any case I believe we can get a decision this month if the pattern follows previous FO Councils. Pierre: By definition the deliberation does not stop our work. Anyway end of month works for … timing for requesting transition to CR. Nigel: For the collections of documents, you want an assertion for each document whether it passes or fails? Pierre: For the synthetic ones, its our responsibility to generate those. … For third parties, e.g. Netflix, BBC, it's up to them to say whether they think a document should pass … or fail, and report whether the implementation agreed with their expectation. … If it agrees, there's nothing more to do. … If it does not agree, then we have to determine what to do. … It could be the content is invalid, an error in the spec, an error in the implementation. Atsushi: One concern with building a test suite for HRM. It needs to have at least … two generated documents from different implementations. … Should there be some example of presentation? … And IMSC-HRM implementation will go over that and generate a pass/fail result. … If I am correct I think we need to have some descriptive note for our test case? Pierre: My proposal is that we ask folks like BBC, like Netflix and others to test their commercial content. … That would be their criteria. Content that they use commercially or plan to use commercially. … We cannot specify any particular style, it's different for every provider. … That's what's most useful for the industry - it will tell us if the HRM is useful, and right. Atsushi: Usually, just seeing it built against each API call or value definition is ideal. I'm not sure how … to convince readers of the implementation report that it covers all defined functionality in the HRM. … Like which test is related to each definition, etc. It's difficult to regenerate the cases. Pierre: I agree it's different than other specs, e.g. API based specs, for sure. … We cannot control what people create commercially which ultimately is what people care about. … It does not fit the template of API specs. Nigel: If we were to be able to show that the HRM is successful at selecting between content that plays … successfully on some player and content that does not, that would be really useful. Pierre: We can fairly easily architect a synthetic test that presents alright but is likely to cause most players … to have a problem, and is rejected by the HRM. … Then we could invite folks with players to try it. We could do that too. Nigel: That's the big unknown to me, how well the HRM tracks real world playability - that's really hard to grasp. Pierre: It would be helpful actually to generate synthetic documents. … Any objection to the overall approach, before I start working on it? Cyril: No, this is fine, but maybe we should wait for the FO Council? … You might waste effort. Pierre: I think we can address their conclusions later. SUMMARY: No immediate objections, Pierre to proceed. TTWG to continue reviewing. github-bot, end topic Pierre: Thanks for the feedback. DAPT Cyril: Suggest scheduling an editor's session Nigel: +1 let's arrange offline Cyril: OK Meeting close Nigel: We're over-time - thanks everyone. Next call in 2 weeks. [rrsagent, make minutes] Minutes manually created (not a transcript), formatted by [17]scribe.perl version 196 (Thu Oct 27 17:06:44 2022 UTC). [17] https://w3c.github.io/scribe2/scribedoc.html
Received on Thursday, 10 November 2022 17:30:57 UTC