IRC log of tt on 2018-07-12

Timestamps are in UTC.

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logging to https://www.w3.org/2018/07/12-tt-irc

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Meeting: Timed Text Working Group Teleconference

13:59:38 [trackbot]

Date: 12 July 2018

14:00:04 [nigel]

Log: https://www.w3.org/2018/07/12-tt-irc

14:00:19 [nigel]

scribe: nigel

14:00:30 [nigel]

Present: Andreas, Nigel

14:00:36 [nigel]

Regrets: Cyril, Glenn

14:00:39 [nigel]

Chair: Nigel

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i'm just now trying to join, but I'm connecting from an iffy wifi from the French West Indies

14:05:50 [nigel]

Present+ Cyril

14:05:53 [nigel]

Regrets- Cyril

14:06:06 [nigel]

Topic: This meeting

14:06:19 [nigel]

Andreas: If there's time I'd like to discuss switching this meeting to be based on UTC time

14:06:21 [nigel]

Nigel: OK

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14:08:38 [nigel]

Present+ Glenn

14:08:41 [nigel]

Regrets- Glenn

14:09:02 [nigel]

Nigel: I think we have limited W3 staff availability so probably that means regrets from Thierry.

14:09:29 [nigel]

.. For the agenda today, we have the usual TTML1, TTML2, IMSC 1.1.

14:09:41 [nigel]

.. Any particular points that anyone wants us to make sure we cover, or other business?

14:09:56 [nigel]

.. (noting Andreas already raised another business agenda item)

14:10:08 [nigel]

group: [silence]

14:10:30 [nigel]

Nigel: Okay, we'll handle the Other Business at the end.

14:10:42 [nigel]

Topic: TTML1

14:10:47 [nigel]

action-513?

14:10:48 [trackbot]

action-513 -- Pierre-Anthony Lemieux to Look at ttml2 backporting to ttml1 3rd ed to see if we can change the ref from ttml2 to point to 3rd ed. -- due 2018-07-05 -- OPEN

14:10:48 [trackbot]

https://www.w3.org/AudioVideo/TT/tracker/actions/513

14:11:41 [nigel]

Nigel: Just a quick update that earlier today I managed to ask Philippe about if it would

14:12:31 [nigel]

.. be possible to make an update to TTML1 3rd Edition CR that incorporates text

14:12:56 [nigel]

.. already subject to an exclusion request from TTML2 without causing the TTML1

14:13:07 [nigel]

.. 3rd Edition Rec date to be pushed out beyond TTML2 Rec.

14:14:19 [nigel]

Pierre: All the outstanding backport changes are in pull requests on TTML1 3rd Ed.

14:14:22 [nigel]

.. I couldn't find any others.

14:14:26 [nigel]

Nigel: Okay, thank you.

14:15:00 [nigel]

Action-513: Pierre reports All the outstanding backport changes are in pull requests on TTML1 3rd Ed.

14:15:00 [trackbot]

Notes added to Action-513 Look at ttml2 backporting to ttml1 3rd ed to see if we can change the ref from ttml2 to point to 3rd ed..

14:15:41 [nigel]

Cyril: Q: Why are we considering the change to TTML1 3rd ed ref to be substantive?

14:15:53 [nigel]

Nigel: We're not - the concern is that the TTML2 Rec publication could be delayed if we

14:16:01 [nigel]

.. have to wait for TTML1 3rd Ed to be at Rec.

14:16:20 [nigel]

.. I'm hoping for a response early next week.

14:16:36 [nigel]

Cyril: What are the options?

14:16:50 [nigel]

Nigel: In an ideal world we would be able to publish both TTML1 3rd Ed and TTML2 Rec at the same time.

14:16:54 [nigel]

Cyril: That'd be great.

14:17:13 [nigel]

Glenn: The question is when - at the same time as TTML2 Rec is currently on track for publication, or with some delay?

14:17:17 [nigel]

Nigel: Exactly.

14:17:29 [nigel]

Glenn: As a reminder, due to a question I had fielded, TTML2 now normatively references

14:17:47 [nigel]

.. TTML1 because we reference it in 117 places normatively, 3 places for DFXP profiles

14:17:59 [nigel]

.. and 114 places where we refer to TTML1 feature definitions.

14:18:10 [nigel]

Cyril: We're doing that for convenience, right, not because we need to.

14:18:24 [nigel]

Glenn: The problem is it was hard to define the feature designators in TTML1 without

14:18:36 [nigel]

.. incorporating the whole text of TTML1 so we had to resort to referring to them directly.

14:18:48 [nigel]

.. We don't copy the DFXP profiles into TTML2, but refer to the normative definition in TTML1.

14:18:58 [nigel]

close action-513

14:18:58 [trackbot]

Closed action-513.

14:20:00 [nigel]

Nigel: Looking at TTML1 pull requests, there's one for lineHeight="normal" text and

14:20:11 [nigel]

.. I see that Andreas a concern.

14:20:24 [nigel]

Andreas: Yes, I've been away for a while and have now reviewed it.

14:20:35 [nigel]

.. I have a concern that the algorithm can not always be followed.

14:20:46 [nigel]

.. The algorithm might not have access to the font properties of a font file, which would

14:21:00 [nigel]

.. be needed. And secondly if the text is kept as is then some terms need to be clearer.

14:21:13 [nigel]

.. It is not unambiguous how altitude and descent are used.

14:21:31 [nigel]

Glenn: Text altitude and text descent are defined properties and traits in XSL-FO and

14:21:48 [nigel]

.. are referred to in CSS 2.1 under the behaviour for line-height so I don't think there's

14:21:51 [nigel]

.. any problem there.

14:22:05 [nigel]

.. Re font metrics, the language is based on the availability of access to those, and if they

14:22:14 [nigel]

.. are not available then the 125% applies, so that's also okay.

14:22:27 [nigel]

.. The only place where I contemplate it might not be available is with bitmap fonts which

14:22:34 [nigel]

.. might be restricted in what metrics are available.

14:22:48 [nigel]

Andreas: I recently discussed with CSS people why some calculations are not available

14:22:59 [nigel]

.. in the browser or developer console especially the font that is used for rendering.

14:23:09 [nigel]

.. They explained that it is not available to the browser stack because it is handled by

14:23:19 [nigel]

.. a lower level in the OS so I am not really sure that it is available.

14:23:36 [nigel]

.. With altitude and descent I am not happy with that. Normally ascender and descender

14:23:47 [nigel]

.. are used and even in XSL-FO it is not always clear what it is because in OpenType

14:24:08 [nigel]

.. for example there are different general properties for ascender and descender so it

14:24:22 [nigel]

.. is not clear which is meant. The text used here is not in XSL-FO or CSS so it is not a

14:24:28 [nigel]

.. reference to those specs at all.

14:24:44 [nigel]

Glenn: I would invite you to re-read CSS 2.2 §10.8. I don't think there's any real ambiguity.

14:24:56 [nigel]

.. Regarding referencing a specific font format we don't want to do that because it ties

14:25:00 [nigel]

.. too much to implementation specifics.

14:25:15 [nigel]

.. Whoever you talked to maybe didn't understand the specifics - all of the browsers do

14:25:30 [nigel]

.. in fact have access to low level font information. I've reviewed the code in Chrome and

14:25:35 [nigel]

.. Firefox and they are using them directly.

14:25:49 [nigel]

Andreas: Ok I don't think we will come to a conclusion here but we need someone more

14:26:04 [nigel]

.. familiar with browser development. The other thing is we have introduced new text,

14:26:32 [nigel]

.. in general the text is okay but it introduces some more complexity. Possibly it would

14:26:42 [nigel]

.. have been easier to just take what is in CSS than to introduce a new algorithm.

14:26:55 [nigel]

Glenn: One important thing is the way we crafted the language in that algorithm, in step

14:27:19 [nigel]

.. 5 or 6, it says "unless there is an implementation requirement ..." use 125% as a fallback

14:27:33 [nigel]

.. so that leaves the implementation free to decide what it wants to use, and can apply

14:27:46 [nigel]

.. its own rules. So there's no technical problem with the algorithm that prevents an

14:27:51 [nigel]

.. implementation from doing what it wants.

14:28:12 [nigel]

.. The CSS folks have said at least half of what is written in CSS is wrong and they have not

14:28:19 [nigel]

.. decided which half is wrong.

14:28:24 [nigel]

Andreas: Okay that does not help!

14:28:42 [nigel]

.. I do not want to block publication. A minor tweak is to make the algorithm or 125%

14:28:53 [nigel]

.. equivalent. At the moment the preference is to use the algorithm. It only gives

14:29:07 [nigel]

.. a fallback option if the font details are not available. It could be made clearer at the

14:29:12 [nigel]

.. beginning that either option can be chosen.

14:29:24 [nigel]

.. You can also add the constraint that in case there is no implementation specific

14:29:37 [nigel]

.. requirement to do otherwise then you could use the algorithm or 125%.

14:29:54 [nigel]

Glenn: I'm looking now, and step 5 says if the font is associated with ... then lh is set

14:30:05 [nigel]

.. accordingly, otherwise step 6 says implementation dependent, but in the absence

14:30:18 [nigel]

.. of implementation specific requirements, use 125%. The way that language is specified,

14:30:34 [nigel]

.. font metrics are not required, and implementations can define their own behaviour or

14:30:48 [nigel]

.. use 125%. I don't see any problem with the algorithm in implementing it or its intention.

14:31:05 [nigel]

.. By the way Pierre and I carefully reviewed this and came up with it as a compromise

14:31:18 [nigel]

.. to deal with another issue so I am very reluctant to tweak it any further.

14:31:58 [nigel]

Pierre: I think all other things being equal, my preference would be to say it is implementation

14:32:09 [nigel]

.. dependent, period, but doing that will result in a pretty drastic change in TTML2 so

14:32:20 [nigel]

.. I'm not sure that is possible right now or desirable. There's a note that says the goal

14:32:32 [nigel]

.. is to be consistent with CSS. If we find it is not consistent then it would be easy to

14:32:42 [nigel]

.. motivate a change. I think this text is an improvement to TTML1 2nd Ed for sure.

14:32:56 [nigel]

Andreas: I agree with Pierre, to leave it completely implementation dependent would be

14:33:10 [nigel]

.. the easiest because other things confuse people more. If there is not a strong

14:33:25 [nigel]

.. opinion or support to change it then leave it as it is. I would definitely look up the

14:33:32 [nigel]

.. terms and possibly change those if necessary.

14:33:44 [nigel]

Pierre: If you want to capture what it should be as an issue then that could be addressed

14:33:48 [nigel]

.. in a future edition.

14:34:02 [nigel]

Andreas: At least in step 5 it is a minor change to tweak the terms. Is that still feasible

14:34:12 [nigel]

.. or is it too late?

14:34:16 [nigel]

Nigel: In TTML1 and TTML2?

14:34:20 [nigel]

Andreas: Both

14:34:23 [nigel]

Cyril: I think it is too late.

14:34:37 [nigel]

.. I don't think it is a problem because IMSC recommends setting a specific value.

14:35:02 [nigel]

Nigel: Pierre didn't you feed back that setting a specific value makes nobody happy?

14:35:14 [nigel]

Glenn: One minor editorial change I would make in TTML2 and TTML1 maybe:

14:35:32 [nigel]

.. we use "altitude (A)" and "descent (D)" - we should make it more consistent by using

14:35:53 [nigel]

.. "ascent" instead of "altitude" to make it more consistent. In TTML2 it has a note

14:35:57 [nigel]

.. about the ascent and descent.

14:36:11 [nigel]

.. Do you think I should make that editorial change?

14:36:17 [nigel]

Andreas: For me, I would welcome the change.

14:36:27 [nigel]

Glenn: Okay that sounds good to me, I can put an editorial issue in to fix that.

14:36:32 [nigel]

.. I'll take care of that.

14:36:47 [nigel]

Cyril: I was looking at the lineHeight constraints in IMSC, and it still says that implementation

14:37:05 [nigel]

.. of "normal" is not consistent so should not be used. The intent is there, reading it

14:37:15 [nigel]

.. now I think we should probably tweak that text also because we have the initial

14:37:27 [nigel]

.. element in IMSC 1.1, so we could set it using initial to a value other than "normal".

14:38:01 [nigel]

Glenn: It turns out that there's a challenge with respect to specifying a distinct line height

14:38:44 [nigel]

.. value as opposed to normal. It is inherited by the inline elements of a paragraph and

14:38:54 [nigel]

.. used to calculate the half leading of the inline elements, but if you use normal then

14:39:24 [nigel]

.. the value of normal is resolved on a per inline basis but if you specify an explicit value

14:39:36 [nigel]

.. on p then that exact value is applied to each inline and that can cause problems if

14:39:43 [nigel]

.. the font size of the inline is larger than that size.

14:39:59 [nigel]

Cyril: Sure, but the author should know that if they set a line height value explicitly then

14:40:10 [nigel]

.. it should deal with the inline childrens' heights.

14:40:24 [nigel]

Glenn: If you have an inline whose font size is twice the p font size and you specify a

14:40:44 [nigel]

.. line height that is smaller then you will end up with negative half leading, but in any

14:40:55 [nigel]

.. case the author is in control. I'm wondering if that recommendation could potentially

14:41:07 [nigel]

.. cause authorial problems but maybe we don't need to deal with that right now. I just

14:41:10 [nigel]

.. wanted to take note of it.

14:41:53 [nigel]

Cyril: I will raise an issue on IMSC 1.1 so we can fix it.

14:42:02 [nigel]

Pierre: There's an informative note on TTML2 with similar language.

14:42:08 [nigel]

Cyril: Related to initial?

14:42:17 [nigel]

Pierre: No but to setting an explicit value for lineHeight.

14:42:29 [glenn]

using explicit LH on P may result in negative half-leading on child SPANs, and thus cause inline glyph areas to overlap prior or subsequent line areas

14:42:32 [nigel]

Nigel: That discussion related to https://github.com/w3c/ttml1/pull/355 by the way

14:44:01 [nigel]

Topic: Update tts:lineHeight='normal' algorithm to match TTML2 ttml1#355

14:44:06 [nigel]

github: https://github.com/w3c/ttml1/pull/355

14:44:20 [nigel]

Nigel: See discussion above in the minutes from this meeting by the way.

14:44:32 [nigel]

Pierre: Nigel you raised the point about the note being removed.

14:44:47 [nigel]

Nigel: Yes, thank you for the reminder. This is about the note that helpfully explained that

14:45:09 [nigel]

.. using lineHeight="125%" and fontSize="0.8c" could be used to get lines that fit in 1c

14:45:10 [nigel]

.. height.

14:45:23 [nigel]

.. The current pull request removes that note, and I wanted to put it back.

14:46:04 [nigel]

Pierre: As we know the actual space between line boxes is not guaranteed to be the

14:46:16 [nigel]

.. specified value of lineHeight. My conclusion is that for folks that expect to be able

14:46:32 [nigel]

.. to reproduce the exact grid they were accustomed to in old systems that cannot be

14:46:39 [nigel]

.. done reliably. You can get close most of the time.

14:46:55 [nigel]

Glenn: You can construct scenarios where it can be made so, for example by making

14:47:08 [nigel]

.. none of the descendant elements specify a font size at all. To try to explain in a note

14:47:22 [nigel]

.. this very complicated subject I would prefer to leave the note out. I'm not inclined

14:47:36 [nigel]

.. to add it back in.

14:48:25 [nigel]

Andreas: My view is similar to what Pierre said - the value "normal" interpretation is

14:48:40 [nigel]

.. messed up. I think it is not really necessary to repeat the note, because if you go

14:48:50 [nigel]

.. from a grid based layout to TTML then there may be another specification like EBU-TT

14:49:00 [nigel]

.. that could point out the possible use of 125% for that reason.

14:49:21 [nigel]

.. I still think that it could be good advice for some transformation to recommend

14:49:33 [nigel]

.. transforming grid based layouts to TTML and back, although you cannot guarantee

14:49:42 [nigel]

.. the same presentation. It is still a valid recommendation but it does not have to be in

14:49:44 [nigel]

.. TTML.

14:50:04 [nigel]

Nigel: Okay, I'm not going stick this one out and have recorded that I feel we have lost

14:50:07 [nigel]

.. something helpful.

14:50:22 [nigel]

.. Let's conclude not to add the note back in now.

14:50:42 [nigel]

.. Moving on to the next point about resolved computed vs computed, Glenn you had a point:

14:50:54 [nigel]

Glenn: We can't remove the "resolved computed value" and go back to "computed value"

14:51:06 [nigel]

.. because the "computed value" is the inherited value and the special inheritance semantics

14:51:20 [nigel]

.. dictate that the computed value is inherited. We can only talk about the algorithm

14:51:34 [nigel]

.. to produce the actual lineHeight to take into account the input and the output value.

14:51:47 [nigel]

.. I used the phrase "resolved computed value" which seemed like the best option without

14:51:58 [nigel]

.. adopting "used value" as per CSS which is not used in XSL-FO.

14:52:11 [nigel]

.. As to adding the special inheritance section note, Pierre is correct that we should have

14:52:20 [nigel]

.. added it in to TTML2 but failed to do that.

14:52:35 [nigel]

Nigel: I read it a different way, namely that the text changes removed the need for that

14:52:41 [nigel]

.. special inheritance semantics section.

14:52:47 [nigel]

Glenn: You might be right in part.

14:52:52 [nigel]

.. It is not entirely clear.

14:53:07 [nigel]

.. CSS actually explicitly says it whereas XSL-FO marginally says it, in one place but not another.

14:53:25 [nigel]

.. It's indirect in §4.5 under line areas. It's not bad to have the explicit section on

14:53:39 [nigel]

.. special inheritance here. Since we could not add it normatively in TTML2 CR2 we had

14:53:43 [nigel]

.. to resort to a note.

14:54:37 [nigel]

Nigel: Okay, I had read it a different way and Pierre and Glenn think the special inheritance

14:54:50 [nigel]

.. section is useful. I don't think it is harmful just that we had cleverly avoided the need

14:54:54 [nigel]

.. for some unnecessary spec text.

14:55:16 [nigel]

.. I am happy to keep it. We should have an issue on TTML2 to add it back in.

14:55:23 [nigel]

Glenn: I can add that issue and mark it as ttml.next.

14:55:28 [nigel]

Nigel: Okay that works for me.

14:56:44 [nigel]

SUMMARY: @skynavga to make an editorial tweak from altitude to ascent in TTML2 and @palemieux to port that back into this pull request.

14:57:36 [nigel]

Topic: TTML1 3rd Edition CR2

14:57:59 [nigel]

Nigel: I understand Pierre is requesting a CfC to publish TTML1 3rd Ed CR2 based on

14:58:22 [nigel]

.. the two open pull requests #355 and #356 when the edits just approved in principle

14:58:29 [nigel]

.. have been applied to #355.

14:58:33 [nigel]

Pierre: Yes

14:59:33 [nigel]

PROPOSAL: After the editorial tweak to #355 agreed above, merge #355 and #356 early and generate a CR2 draft for review with intent to request transition after the normal 10 working day period.

14:59:44 [nigel]

Pierre: That's good with me.

14:59:49 [nigel]

Nigel: Any objections?

14:59:56 [nigel]

group: [silence]

15:00:04 [nigel]

RESOLUTION: After the editorial tweak to #355 agreed above, merge #355 and #356 early and generate a CR2 draft for review with intent to request transition after the normal 10 working day period.

15:00:20 [nigel]

Nigel: Okay, when those tweaks are made Pierre please ping me and I will issue a CfC.

15:00:53 [nigel]

Cyril: Given the potential problem of timeline with TTML2 if it helps would it be possible

15:01:02 [nigel]

.. to request transition earlier than 10 working days?

15:01:14 [nigel]

Nigel: No, I don't believe it would be possible, but I also don't believe it would help.

15:03:10 [nigel]

.. The transition request cannot be executed before the group's decision is final, though

15:03:23 [nigel]

.. we could get those pull requests merged earlier.

15:03:32 [nigel]

Glenn: I agree I don't think you could squeeze those 10 days by process.

15:03:42 [nigel]

Pierre: [drops off the call, with apologies]

15:05:05 [nigel]

Nigel: Regardless of whether or not we can squeeze TTML1 3rd Ed out a week early,

15:05:33 [nigel]

.. we still have the exclusion period question referenced above, so I don't think it would make much difference.

15:05:58 [nigel]

Glenn: Regarding adopting TTML1 3rd Ed from TTML2 we could change to a generic

15:06:31 [nigel]

.. non-dated reference, or we could leave as is and then anyone traversing the link would

15:06:39 [nigel]

.. get a warning that it is not the latest version.

15:06:53 [nigel]

Nigel: Even so that doesn't change the semantic basis.

15:07:02 [nigel]

Glenn: That's true unless we change the reference to be non-specific.

15:07:11 [nigel]

Nigel: True but I think we decided not do that before.

15:07:24 [nigel]

Glenn: If you pull up TTML1 2nd Ed it says that it is outdated.

15:07:52 [nigel]

Nigel: We don't have to decide this right now - I propose we wait for a response from

15:07:54 [nigel]

.. Philippe.

15:08:03 [nigel]

Glenn: I agree. To reiterate for the minutes, three options:

15:08:15 [nigel]

.. 1. Leave as 2nd Ed ref, resulting in an out of date message

15:08:31 [nigel]

.. 2. Supersede it formally which we could do after publishing TTML2.

15:08:35 [nigel]

Nigel: That doesn't really help.

15:08:45 [nigel]

Glenn: If it is formally superseded that emphasises the outdated message.

15:08:57 [nigel]

.. 3. Change to a non-specific reference, which goes back on our previous policy.

15:09:45 [nigel]

Nigel: When we supersede a spec the URL changes so we would run the risk of

15:09:51 [nigel]

.. breaking the just-published TTML2.

15:10:02 [nigel]

.. You can check this with IMSC1.

15:10:52 [nigel]

Topic: IMSC 1.1 CR2

15:11:04 [nigel]

Nigel: The CfC for IMSC 1.1 CR2 ends tomorrow I believe, and I'm not aware of any

15:11:19 [nigel]

.. objections to proceeding with the request for transition at this time.

15:11:32 [nigel]

.. Since Thierry is not on the call I can't ask him now to prepare the transition request

15:11:37 [nigel]

.. but will do that offline.

15:11:57 [nigel]

.. Hopefully that transition request can be raised on Monday (if not before!).

15:12:38 [nigel]

Topic: Future meetings timings

15:12:51 [nigel]

Nigel: Andreas reminded me at the top of this call that some groups are switching to

15:13:04 [nigel]

.. have meeting times based on UTC instead of Boston time, to simplify (slightly) the

15:13:13 [nigel]

.. issue of daylight savings time changes.

15:13:28 [nigel]

Andreas: Yes, it was discussed at the AC meeting in May and I think everybody agreed

15:13:39 [nigel]

.. it would be easier not just because of DST but also if new members join the call it

15:13:51 [nigel]

.. is easier to find out when the call is. It is not urgent but I would propose if nobody

15:13:57 [nigel]

.. objects to switch to UTC instead of Boston time.

15:14:05 [nigel]

Nigel: You're not proposing to change the time?

15:14:14 [nigel]

Andreas: No, only the time zone.

15:14:17 [nigel]

Nigel: Okay.

15:15:18 [nigel]

PROPOSAL: Base the meeting time on UTC rather than Boston time for future meetings, i.e. 1400 UTC every Thursday.

15:15:30 [nigel]

Nigel: Any objections?

15:15:38 [nigel]

group: [silence]

15:15:54 [nigel]

Nigel: Okay what I will do is highlight this resolution in the minutes in case anyone

15:16:02 [nigel]

.. has later thoughts about it or has a view but is not on this call.

15:16:20 [nigel]

Andreas: The other proposal that is useful for new people is to include meeting invites

15:16:23 [nigel]

.. in your invitation.

15:17:15 [nigel]

Nigel: Yes that's a good idea, I think I can do that. I'll look into how to do it. Thanks

15:17:27 [nigel]

.. for the proposal, I will do that when the resolution to change the time zone has been

15:17:36 [nigel]

.. finalised. I don't think I need a special resolution for that decision.

15:17:48 [nigel]

.. Good ideas, thank you.

15:18:36 [nigel]

Topic: TTML2

15:19:00 [nigel]

Nigel: I wonder if we can get to a resolution on ttml2#867?

15:19:11 [nigel]

Glenn: We should have a private conversation because we're not on the same page.

15:19:24 [nigel]

Nigel: Good idea, your audio is breaking up a little so probably better than doing it now.

15:19:32 [nigel]

Glenn: Let's try to do it soon, maybe early next week?

15:19:35 [nigel]

Nigel: Yes.

15:19:55 [nigel]

Glenn: Maybe 18th-20th I will have better connectivity.

15:20:03 [nigel]

s/0th/2nd

15:21:02 [nigel]

Nigel: I'll send you an invite.

15:21:45 [nigel]

Topic: Unicode bidi should probably not be animatable. ttml2#881

15:21:51 [nigel]

github: https://github.com/w3c/ttml2/issues/881

15:22:05 [nigel]

Nigel: Quick update - I have asked Philippe, and hope to hear back from him perhaps

15:22:15 [nigel]

.. early next week - I think W3 staff availability is currently limited.

15:22:30 [nigel]

SUMMARY: Request sent by @nigelmegitt to @plehegar

15:23:10 [nigel]

Topic: Clarify that construct effective {content,processor} profile is performed only once. ttml2#860

15:23:17 [nigel]

github: https://github.com/w3c/ttml2/issues/860

15:23:30 [nigel]

SUMMARY: @skynavga and @nigelmegitt to discuss offline

15:23:34 [nigel]

github-bot, end topic

15:24:07 [nigel]

Topic: Clarify that [validate document] may produce false positive results. ttml2#876

15:24:16 [nigel]

github: https://github.com/w3c/ttml2/issues/876

15:24:30 [nigel]

Glenn: I'll fix the typos. We already have a note on false positives that talks about a more

15:24:45 [nigel]

.. generalised value syntax in the schema than the spec, in the section on schemas.

15:25:02 [nigel]

.. In section 4.1, a long note. I could refer to that note here.

15:25:12 [nigel]

.. It wasn't so much the schema false positives I was thinking of when I wrote this

15:25:24 [nigel]

.. material but the more complex restrictions that are not at all expressible in a schema,

15:25:34 [nigel]

.. for example all the constraints about ruby, as well as many other cases.

15:25:49 [nigel]

.. Unless you consider your schema to include code, which I do, I define the set of

15:26:06 [nigel]

.. potential schemas as including programming code, then that note could make it

15:26:09 [nigel]

.. less abstract.

15:26:13 [nigel]

Nigel: Yes that would work.

15:27:40 [nigel]

.. More generally the reductive interpretation of this is to say that implementations might

15:28:05 [nigel]

.. not be complete, which is true of almost everything, so why call this one out particularly?

15:28:44 [nigel]

Glenn: I agree, this note and all others could be removed without changing the

15:28:49 [nigel]

.. normative text.

15:29:04 [nigel]

.. People might think that putting "prohibited" in a profile might lead a validation processor

15:29:16 [nigel]

.. to catch it. I want to ward off those kind of readings by pointing out that the language

15:29:33 [nigel]

.. on validation is based on "if something is detected" rather than requiring detection of

15:29:50 [nigel]

.. every possible error. It doesn't hurt to say it, unless you dispute that it is factually correct.

15:29:57 [nigel]

.. I would dispute that it's factually wrong.

15:30:00 [nigel]

Nigel: Ok

15:30:13 [nigel]

Glenn: We don't precisely define the behaviour of what happens when something

15:30:29 [nigel]

.. violates a constraint. In some cases we specify a fallback but in others we don't. We

15:30:47 [nigel]

.. also don't set threshold rules about when aborting should happen.

15:31:23 [nigel]

.. I'm just trying to help the reader out - my re-reading made me think that there was

15:31:28 [nigel]

.. potential for misleading the reader.

15:31:41 [nigel]

Glenn: I'll make those two fixes and maybe you can consider that.

15:31:44 [nigel]

Nigel: Okay will do.

15:32:11 [nigel]

SUMMARY: @skynavga to make edits discussed above and @nigelmegitt to re-review

15:32:15 [nigel]

github-bot, end topic

15:33:58 [nigel]

Topic: text profile should support anamorphic fonts imsc#419

15:34:03 [nigel]

github: https://github.com/w3c/imsc/issues/419

15:34:09 [nigel]

Cyril: I raised this issue this morning.

15:34:24 [nigel]

Nigel: I think this needs to go to requirements first, but we can discuss it here now.

15:35:20 [nigel]

Cyril: Anamorphic fonts is a feature we use quite heavily. It is a de facto practice

15:35:31 [nigel]

.. that was inherited from lambda cap. I suspect it is not easy to define two glyphs

15:35:46 [nigel]

.. that are completely distinguishable within the em box, which may be why stretching

15:35:54 [nigel]

.. is used instead of using specific fonts.

15:36:38 [nigel]

Nigel: Is there any other way to achieve the result than to use fontSize with two components?

15:37:03 [nigel]

Glenn: You mentioned two specific characters, distinguished by stretching. Practically

15:37:14 [nigel]

.. speaking, just not stretching either of them and requiring the reader to use context

15:37:23 [nigel]

.. to figure out which is which is not a horrible way to deal with this.

15:37:37 [nigel]

Cyril: Our QC team clearly told me this is not acceptable.

15:37:50 [nigel]

Glenn: Okay, I understand, though I think Japanese readers can fill in the blanks and

15:37:53 [nigel]

.. distinguish them.

15:38:10 [nigel]

Cyril: There's clearly ambiguity and we want to distinguish these cases.

15:38:20 [nigel]

Glenn: It's a really high cost for what I consider really low value.

15:38:37 [nigel]

Cyril: I understand that, which is why I suggested adding restrictions. I am open to any

15:38:40 [nigel]

.. suggestions.

15:38:54 [nigel]

Pierre: Before we go there, for the record, my interaction with folks other than Cyril

15:39:18 [nigel]

.. who work with Japanese subtitles has been consistent with what I heard from Glenn.

15:39:31 [nigel]

.. I think we need a separate meeting with interested parties to work out the solution.

15:39:40 [nigel]

Cyril: Sure, I'm concerned about the timelines.

15:39:53 [nigel]

Pierre: I do not think it can be implemented in CSS.

15:40:06 [nigel]

Cyril: We can set up this meeting. I do not want to delay the process. What I can think

15:40:15 [nigel]

.. of for today is to add the feature and mark it as at risk?

15:40:28 [nigel]

Pierre: No, it is just not implementable in CSS. If you can point to a way it could be

15:40:34 [nigel]

.. implemented that would address my concerns.

15:40:49 [nigel]

Glenn: One of the things you mentioned is different glyphs. The implementation is free

15:41:06 [nigel]

.. to map to whatever glyphs it wishes. One implementation approach would be to

15:41:19 [nigel]

.. select different glyphs with intrinsically different widths. That would not require the

15:41:34 [nigel]

.. general ability to specify an anamorphic font, which is a much costlier thing for

15:41:36 [nigel]

.. implementation.

15:41:48 [nigel]

Pierre: When I experimented with fonts, some of them showed a much bigger difference

15:42:07 [nigel]

.. between those two characters than others. Like in some Latin fonts it can be hard to

15:42:18 [nigel]

.. tell an O from a 0 or an l from a 1.

15:42:22 [nigel]

Glenn: Yes that's exactly the point.

15:42:34 [nigel]

Cyril: Okay I will come back to you on this issue but it might be a blocker for us to

15:42:37 [nigel]

.. progress IMSC.

15:42:41 [nigel]

Pierre: Understood.

15:42:49 [nigel]

Glenn: In a sense I view this as a quality of implementation issue.

15:43:03 [nigel]

Pierre: That's where I am but maybe there's more information to bring to the table that I don't know yet.

15:43:17 [nigel]

Glenn: If this is the only example then anamorphic fonts is overkill.

15:43:38 [nigel]

Cyril: It's not anamorphic fonts but the right restrictions to make it not overkill.

15:43:51 [nigel]

Glenn: If you tweak the character then you're proposing a generic property that can

15:44:03 [nigel]

.. apply to any character, not just the ones that have the problem. That's a more generic

15:44:14 [nigel]

.. solution to this problem. You have to raise the cost vs gain comparison here.

15:45:05 [nigel]

Nigel: I think looking for other ways to achieve an acceptable result is the way forward here.

15:45:14 [nigel]

.. For example in SVG you could apply a transform, and maybe in CSS?

15:45:23 [nigel]

Glenn: Only on block containers in CSS, not inlines.

15:45:40 [nigel]

Cyril: If it is not used then why is it in LambdaCap?

15:45:50 [nigel]

.. We ingest content with that feature in.

15:46:04 [nigel]

Pierre: I'm guessing here, but one possibility is there's only one font that is used in

15:46:10 [nigel]

.. LambdaCap. That could be a reason.

15:46:24 [nigel]

Glenn: Actually LambdaCap has 6-10 font families that it can select.

15:46:40 [nigel]

.. We implemented this in TTML2 with generic stretching. There is a pretty heavy toll

15:46:51 [nigel]

.. on the implementation to support anamorphic fonts. For example you have to have

15:47:04 [nigel]

.. anamorphic whitespace as well as anamorphic glyphs. There is a whole bunch of things

15:47:06 [nigel]

.. that it affects.

15:47:15 [nigel]

Cyril: Okay I'll come back to you on this one.

15:47:31 [nigel]

SUMMARY: @cconcolato to review and come back with further thoughts.

15:47:36 [nigel]

github-bot, end topic

15:48:19 [nigel]

Topic: tts:origin/tts:position constraint applies to Text profile only imsc#418

15:48:25 [nigel]

github: https://github.com/w3c/imsc/issues/418

15:48:35 [nigel]

Pierre: I think this is editorial, and was planning to address it after CR2.

15:48:42 [nigel]

Nigel: Okay, knowing the plan is useful.

15:48:49 [nigel]

Pierre: This is definitely not fatal.

15:49:25 [nigel]

Nigel: I think this could be considered substantive.

15:49:29 [nigel]

Pierre: I'll address it today.

15:49:46 [nigel]

Topic: lineHeight restriction should not preclude using the initial element imsc#420

15:49:52 [nigel]

github: https://github.com/w3c/imsc/issues/420

15:50:00 [nigel]

Pierre: I plan to address this today, using the same text as in TTML2.

15:50:04 [nigel]

Cyril: Fine

15:50:52 [nigel]

Topic: Address draft CR2 comments imsc#417

15:50:59 [nigel]

github: https://github.com/w3c/imsc/pull/417

15:51:09 [nigel]

Pierre: I addressed your comment Nigel

15:51:59 [nigel]

Nigel: That looks great, thank you!

15:52:05 [nigel]

.. [approves pull request]

15:52:35 [nigel]

github-bot, end topic

15:52:39 [nigel]

Topic: IMSC 1.1 CR2

15:52:53 [nigel]

Nigel: Just noting that we have a small flurry of last minute review comments but I'm fairly

15:53:54 [nigel]

.. relaxed about them, given their nature.

15:54:43 [nigel]

Topic: TPAC 2018

15:54:51 [nigel]

Nigel: Don't forget the early bird rate is still available.

15:54:58 [nigel]

Pierre: And to confirm we are meeting Monday and Tuesday?

15:55:00 [nigel]

Nigel: Yes

15:55:18 [nigel]

.. Note we are likely to have a significant amount of "joint meeting" with M&E IG on the

15:55:33 [nigel]

.. Monday. I'm still open to the idea that we in fact mainly meet with them on the Mondayu

15:55:38 [nigel]

s/yu/y

15:55:53 [nigel]

.. and conduct our TTWG only business on the Tuesday, depending on the volume of

15:55:56 [nigel]

.. topics we have to discuss.

15:56:34 [nigel]

.. Obviously as Chair I'm willing to take input on that.

15:56:56 [nigel]

Topic: Meeting Close

15:59:20 [nigel]

Nigel: Thanks everyone for joining today. See you next week! [adjourns meeting]

15:59:28 [nigel]

rrsagent, make minutes

15:59:28 [RRSAgent]

I have made the request to generate https://www.w3.org/2018/07/12-tt-minutes.html nigel

16:04:05 [nigel]

Regrets: Thierry

16:04:23 [nigel]

s/github-bot, end topic//g

16:04:52 [nigel]

s/i'm just now trying to join, but I'm connecting from an iffy wifi from the French West Indies/

16:09:13 [nigel]

s/.. done reliably. /Pierre: done reliably.

16:11:36 [nigel]

s/SUMMARY: @skynavga to make an editorial tweak from altitude to ascent in TTML2 and @palemieux to port that back into this pull request./SUMMARY: @skynavga to make an editorial tweak from altitude to ascent in TTML2 and @palemieux to port that back into this pull request; @skynavga to raise an issue to add the special inheritance semantics back into TTML2.

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i/Topic: text profile should support/Pierre: [rejoins call]

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rrsagent, make minutes

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rrsagent, make minutes

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