{minutes} 16/1/14 TTWG meeting

Available at: http://www.w3.org/2014/01/16-tt-minutes.html


      [1] http://www.w3.org/

                               - DRAFT -

                Timed Text Working Group Teleconference

16 Jan 2014

   See also: [2]IRC log

      [2] http://www.w3.org/2014/01/16-tt-irc


          nigel, glenn, tmichel, plh, pal, jdsmith, frans_ebu





     * [3]Topics
         1. [4]Charter
         2. [5]Profile Discrepancy
         3. [6]Individual character rotation
         4. [7]Definition of "closest"
         5. [8]IMSC language support - code points, xml:lang etc
         6. [9]back to CLDR
         7. [10]Pending Review Actions
         8. [11]Actions overdue
         9. [12]Change Proposals
     * [13]Summary of Action Items

   <trackbot> Date: 16 January 2014

   <scribe> scribeNick: nigel

   nigel: will be taking part in chairs training next week,
   choices are to proceed next week without me or to cancel and
   reconvene on 30th.

   glenn: suggests cancelling on 23rd

   nigel: okay let's do that.

   <scribe> agenda: Charter


   nigel: some licence drafting has been going on in the
   background, barring adverse comments expect to take new charter
   to AC following edits by plh, towards the end of this week.

Profile Discrepancy


   <trackbot> issue-162 -- update standalone profile documents --


     [14] http://www.w3.org/AudioVideo/TT/tracker/issues/162

   glenn: think we can close the issues.
   ... There was a question about backward compatibility. My
   analysis showed that the previous versions were not up to date.
   If anyone used them then those implementations need to change
   ... They were not compatible with what was published in the
   Rec. I'm happy with the new docs, which have been published.

   nigel: Moved to Pending Review.


   <trackbot> action-141 -- Nigel Megitt to Call for Action to
   identify discrepancies in TTML 1.0 on different profiles. --
   due 2013-02-14 -- PENDINGREVIEW


     [15] http://www.w3.org/AudioVideo/TT/tracker/actions/141

   close action-141

   <trackbot> Closed action-141.


   <trackbot> action-225 -- Glenn Adams to Work with plh to update
   standalone profile docs for ttml1se -- due 2013-10-31 -- OPEN


     [16] http://www.w3.org/AudioVideo/TT/tracker/actions/225

   close action-225

   <trackbot> Closed action-225.

Individual character rotation


   <trackbot> issue-231 -- Individual character rotation --
   pending review


     [17] http://www.w3.org/AudioVideo/TT/tracker/issues/231

   pal: The solution only affects horizontal glyphs with vertical
   layout. Are there any other circumstances in which characters
   may need to be rotated?

   glenn: from the standpoint of normal writing, no, but for
   arbitrary graphics it might be wanted of coure, for artistic
   ... It's not supported now by CSS though it is supported by SVG
   because SVG supports arbitrary angular rotation.

   pal: it's possible to create custom fonts with rotated glyphs
   so this is okay.
   ... I'm happy to close this.

   close issue-231

   <trackbot> Closed issue-231.

   close action-255

   <trackbot> Closed action-255.

Definition of "closest"


   <trackbot> issue-259 -- Define "closest" -- pending review


     [18] http://www.w3.org/AudioVideo/TT/tracker/issues/259

   pal: See comments on issue. Wording would be better to define
   in terms of distance from zero.

   glenn: origin doesn't involve enclosure so rounding towards
   zero seemed more appropriate than for other attributes where
   making further from zero allows for more conservative spacing.
   ... We don't want to make a discrepancy between TTML2 and TTML1
   by changing the way this could work.

   pal: Reference to euclidean distance may mean that this never
   gets implemented correctly.
   ... CFF-TT has specific wording for rounding from percentages
   to pixels using 'round half up' terminology. So there's prior
   implementation that does it differently, independently of

   nigel: is this about the wording or the mathematics?

   pal: no problem with the wording - it's about the mathematics.

   glenn: there are 2 options in the issue, a and b. Is there any
   difference in b between the proposal and the existing solution?

   pal: I think so. Take tts:fontSize for example.


     [19] http://www.w3.org/TR/ttml1/#style-attribute-fontSize

   pal: Euclidean distance requires square root of the sum of the
   squares. If two have the same computational result then choose
   the one furthest from zero.
   ... My suggestion is to round each dimension separately.

   glenn: this is a corner case. Prefer to think about, say,


     [20] http://www.w3.org/TR/ttml1/#style-attribute-padding

   glenn: the difference between the two things? For padding they
   are the same, however distance is not otherwise defined. So I
   used Euclidean distance specifically.

   pal: Imagine there's a computed value for padding that consists
   of 4 lengths - how would you compute the Euclidean distance
   between this value and the next closest - what would be the

   glenn: it would be on a component by component basis.

   pal: I agree, so there's no difference.

   glenn: the key is that this is already implied by the use of
   the term "computed" which is already resolved to the component

   pal: Can we be clear about where "computed" means this?

   glenn: The definition of CSS that we refer to defines this. We
   presume that you include the CSS etc definitions.

   pal: I think we need to be clear about how many components are
   included in this Euclidean computation.

   nigel: which values have multiple dimensions that are managed
   ... is it only color?

   pal: Euclidean distance can be applied to vector values as well
   as scalar values.

   glenn: In the case of padding it is not a vector. For fontSize
   it would be considered a vector.

   nigel: Aren't they two scalars?

   glenn: In the case of scaling of bitmap fonts I definitely
   meant to do a vector comparison.

   nigel: That could be inferred from the notation used but do we
   need to add wording to make it explicit?

   glenn: As we've tried to become more precise it's become more
   complicated. Do we change TTML2 to be different from TTML1, or
   add an errata to TTML1? These are all informative notes at the
   ... We need to consider testing too.

   pal: At least one reader did not have the same interpretation
   as the editor.

   glenn: 2 issues - one is using Euclidean distance; the other is
   about origin in which you're suggesting changing the direction
   of rounding.

   pal: yes.

   glenn: It may be worth separating these into different issues.
   I'm more concerned about one than the other.

   action pal to create a new issue to split these out for

   <trackbot> Created ACTION-257 - Create a new issue to split
   these out for tracking. [on Pierre-Anthony Lemieux - due

   glenn: if we put aside the issue of how distance is defined
   linguistically then on this issue of origin, what are our

   pal: I suggest deferring this issue until later and putting
   higher priority on bigger issues.
   ... I can dig deeper into this and try to get some hard data
   regarding the implementations prior to TTML1SE.

   nigel: Okay we can take this offline, but in the absence of
   further agreement we'll make no edits in TTML2

   glenn: I'm happy to define what is meant by Euclidean distance
   a bit, i.e. in terms of component-wise or vector-wise
   ... In terms of rounding of origin I think it's early enough to
   make a change now without impacting implementations now. We can
   add an errata and a note.
   ... So we can solve both issues in a way that's not too complex
   to implement.

   <pal> sounds good

   <glenn> ACTION: glenn to work with pal to resolve edits needed
   for issue-259 comments [recorded in

   <trackbot> Created ACTION-258 - Work with pal to resolve edits
   needed for issue-259 comments [on Glenn Adams - due

IMSC language support - code points, xml:lang etc


   <trackbot> action-238 -- Pierre-Anthony Lemieux to Follow up on
   issue-295 -- due 2013-12-19 -- PENDINGREVIEW


     [22] http://www.w3.org/AudioVideo/TT/tracker/actions/238


   <trackbot> issue-295 -- Remove code point restrictions from
   IMSC -- open


     [23] http://www.w3.org/AudioVideo/TT/tracker/issues/295

   pal: I have made the edits

   nigel: Glenn are you happy with the updated wording?

   pal: Annex B has been removed entirely and Annex A has been
   refactored to take into account CLDR. The wording has been
   changed to emphasise that this is a set of characters from
   ... authors are encouraged to choose depending on the language
   of the element.

   glenn: I still have some issues with table 2 because of its
   non-inclusive nature. It is a somewhat Euro-centric subset of

   pal: Remember this is a union of the CLDR sets, which still
   apply - it's an addition to them only.

   glenn: The scope is worldwide.

   plh: I did my action item on ATSC - please review. We can also
   close the action on the document licence.
   ... I have updated the charter for the document licence, which
   only applies to WebVTT. I wanted to know where we are on
   action-88 on the media type.
   ... If we don't conclude by Jan 30 there will be another long

   glenn: I haven't added the errata yet but given this info on
   priority I'll pick it up this week.

   plh: I did contact IANA to say we'll get back to them.

   nigel: did you do the EBU wording?

   <plh> ACTION: plh to add EBU wording in charter [recorded in

   <trackbot> Created ACTION-259 - Add ebu wording in charter [on
   Philippe Le H├ęgaret - due 2014-01-23].

   plh: not yet.

   pal: what's the process? Do we review it in the group before it
   goes to AC?

   <plh> [25]http://www.w3.org/2013/10/timed-text-charter.html

     [25] http://www.w3.org/2013/10/timed-text-charter.html

   plh: yes.
   ... I can do a diff too if that's helpful.
   ... I will send diffs to the public group

   nigel: what's the review process?

   plh: I would say a week for this group.
   ... regrets from me for the 30th though I'll be on IRC if

back to CLDR

   pal: Am happy to follow up with Glenn and understand the

   glenn: My preference is to remove table 2 but otherwise to put
   a paragraph in showing that it's a subset of example character
   sets that are believed to apply to the specified set of
   ... To be exhaustive there would need to be citations for every
   language but right now there are no references to normative
   ... That paragraph should also say that others may be added in
   the future.

   pal: That sounds excellent.

   glenn: I've noticed some issues elsewhere.
   ... for example lineHeight.

   nigel: proposes to close actions 238 and 243 and leave 244

   close action-238

   <trackbot> Closed action-238.

   close action-243

   <trackbot> Closed action-243.

   pal: needs to leave soon. any more for me?

   nigel: action-252 overdue


   <trackbot> action-252 -- Pierre-Anthony Lemieux to Add an issue
   for tracking purposes to refactor imsc to conform to the
   content profile specification of ttml2 dependent on ttml2
   profile updates. -- due 2013-12-19 -- OPEN


     [26] http://www.w3.org/AudioVideo/TT/tracker/actions/252

   pal: this is dependent on ttml2 work. I'll do it when I can.

   nigel: will extend the due date so it's not overdue, to 7th
   ... have done that.

Pending Review Actions


   <trackbot> action-203 -- Glenn Adams to Investigate 708 border
   style mapping issues with mike's help -- due 2013-09-26 --


     [27] http://www.w3.org/AudioVideo/TT/tracker/actions/203

   glenn: can't make progress with this as it stands due to lack
   of definition.


   <trackbot> action-214 -- Glenn Adams to Review cp008 and
   consider reformulating the recently added <animate> support to
   better align -- due 2013-10-10 -- PENDINGREVIEW


     [28] http://www.w3.org/AudioVideo/TT/tracker/actions/214

   <jdsmith> I've just marked

   pending review as well.

     [29] https://www.w3.org/AudioVideo/TT/tracker/actions/164

   glenn: we discussed this in detail in the f2f and I've
   implemented it. It has has a long review period.

   <glenn> [30]http://www.w3.org/wiki/TTML/changeProposal008

     [30] http://www.w3.org/wiki/TTML/changeProposal008

   close action-214

   <trackbot> Closed action-214.


   <trackbot> action-219 -- Glenn Adams to Change to rec in ttml2,
   and add note to authors indicating that if author wants
   specific value, then they should specify specific value -- due
   2013-10-24 -- PENDINGREVIEW


     [31] http://www.w3.org/AudioVideo/TT/tracker/actions/219



     [32] https://dvcs.w3.org/hg/ttml/raw-file/default/ttml2/spec/ttml2.html#style-attribute-lineHeight

   glenn: the action as stated has been done.

   nigel: there's still a question of whether it's possible to
   state a value as an alternative to the normal keyword's default
   125% behaviour.
   ... The lineHeight algorithm is now more explicit.

   glenn: I haven't described that algorithm previously on this
   ... [takes a couple of minutes to describe the algorithm to
   turn "normal" into a single computed parameter]
   ... I reviewed blink, webkit and mozilla as to how they resolve
   "normal". They take the paragraph's nominal font, then look at
   Ascent, Descent and line Gap, then take the font size that
   applies and scale
   ... the metrics accordingly. They add the three values together
   to give a computed lineHeight property when the original
   specified value is "normal". If those metrics are not available
   ... then they use 125% of the fontSize that applied to that
   ... So at this level descendent spans with different font sizes
   would not apply.
   ... and the 125% is only used if A, D and G are not available.
   ... There's a separate process for inline elements than for
   block elements.
   ... The lineHeight becomes a minimum value for the line box
   that will be used if there's nothing else in the line box that
   has a greater height.
   ... However if there's an inline box that's a child of the
   linebox that has larger non-replaced text then the A and D will
   be used to increase the overall inline box's height.
   ... And there's separate processing for padding and margin.
   ... Note that when we introduce images we'll have replaced
   content that comes into effect in this algorithm.

   jdsmith: are the new steps consistent with those browsers?

   glenn: yes, this is based on my analysis of those three. I
   didn't analyse IE because I didn't have access to the source
   ... Does MS use this algorithm?

   jdsmith: Was there a different algorithm before?

   glenn: We referred to CSS but that is ambiguous and defers to
   implementations without documenting properly.
   ... Mozilla confirmed that this is what we meant but didn't
   write down in CSS.

   nigel: do we need to formally communicate this to CSSWG?

   glenn: yes we do. In the past we've had comments at Last Calls
   but should call this out specifically.
   ... The formal time to do it is during LC. I can raise it there
   when we have consensus here on this language.
   ... I'd like to make sure that at least pal has an input
   because he's written something different in IMSC.

   action nigel to email group notifying of this change and
   initiating formal approval

   <trackbot> Created ACTION-260 - Email group notifying of this
   change and initiating formal approval [on Nigel Megitt - due


   <trackbot> action-221 -- Glenn Adams to Double check spec
   language on css and xsl-fo around line height stacking strategy
   -- due 2013-10-24 -- PENDINGREVIEW


     [33] http://www.w3.org/AudioVideo/TT/tracker/actions/221

   nigel: this seems to be related to the similar edits.

   action-260: reference changes in both action-219 and action-221

   <trackbot> Notes added to action-260 Email group notifying of
   this change and initiating formal approval.

   close action-219

   <trackbot> Closed action-219.

   close action-221

   <trackbot> Closed action-221.


   <trackbot> action-233 -- Glenn Adams to Reach out to CSS WG to
   understand potential mapping of multi-row-align to CSS -- due
   2013-11-18 -- PENDINGREVIEW


     [34] http://www.w3.org/AudioVideo/TT/tracker/actions/233

   glenn: I queried this, got the answer to use flexbox and
   discovered that this is possible. I tested it on Chrome,
   Firefox and Opera and Safari - it only worked on more recent
   versions on Safari.
   ... I assume IE will work too because it supports flexbox too.



     [35] http://lists.w3.org/Archives/Public/public-tt/2013Nov/0027.html

   glenn: Jerry you might want to have a look at the attachments
   on this message including examples to try.
   ... I will also send a screenshot of what it should look like.

   close action-233

   <trackbot> Closed action-233.

   action jerry and glenn to verify flexbox solution to multi row
   align using IE

   <trackbot> Created ACTION-261 - And glenn to verify flexbox
   solution to multi row align using ie [on Jerry Smith - due

   action-261: this is a follow-up to action-233

   <trackbot> Notes added to action-261 And glenn to verify
   flexbox solution to multi row align using ie.

   glenn: There's still an open question as to how we specify this
   in TTML2 - do we expose flexbox features directly or add some
   specific line alignment syntax
   ... A new property is a shorthand for the use of the flexbox

   action nigel to update relevant change proposal to include row
   alignment requirement and potential CSS solution based on
   action-233 findings

   <trackbot> Created ACTION-262 - Update relevant change proposal
   to include row alignment requirement and potential css solution
   based on action-233 findings [on Nigel Megitt - due

Actions overdue


   <trackbot> action-164 -- Jerry Smith to Investigate interop
   issues using CSS familyName constructs -- due 2013-12-05 --


     [36] http://www.w3.org/AudioVideo/TT/tracker/actions/164

   jdsmith: actually this is pending review
   ... The view was that we should be aligning TTML with CSS.
   There's a short term convenience for tools if we don't put the
   CSS escape mechanism into the XML but it's cleaner to be
   aligned and to
   ... use the CSS escapes.
   ... On another call we said to use XML escapes?

   glenn: whatever tool we use the XML escapes to apply, because
   we use XML. We don't use the stylesheets as syntactically
   defined by CSS, just the value syntax.
   ... So the original use of these escapes came about because
   when you express a CSS stylesheet as a separate resource then
   you can use a backslash U notation.
   ... Since we don't reference external stylesheets that was not
   an issue.
   ... In TTML2 we're using something closer to XSL-FO and SVG for
   attribute value syntax in XML. If we introduce the escape
   mechanism in tokens based on CSS's escaping mechanism then we
   will end up
   ... with 2 mechanisms: the XML one and the CSS one. There's
   redundancy there.

   jdsmith: Yes, I prefer both.

   glenn: This optimisation is in TTML1 as a constraint. In a
   future version of TTML1 we could widen that out to re-include
   the Unicode escapes.
   ... We can certainly include in TTML2 because strict backward
   compatibility isn't required for this.

   jdsmith: I will probably follow this up with a proposal for a

   glenn: Spec-ready text is preferred. The Change Proposal should
   address interoperability with TTML1 re this issue as well, and
   discuss the co-concurrent features of XML numeric character
   ... Should maybe define this in terms of where in the process
   this happens.

Change Proposals


     [37] http://www.w3.org/wiki/TTML/ChangeProposalIndex

   glenn: the 'index' doesn't actually have an index - it would be
   good to edit this to make a true index.

   action nigel to tidy change proposal index page to include an

   <trackbot> Created ACTION-263 - Tidy change proposal index page
   to include an index [on Nigel Megitt - due 2014-01-23].

   action-263: glenn suggests listing a table with each change
   proposal by number with different columns, with status, package

   <trackbot> Notes added to action-263 Tidy change proposal index
   page to include an index.

   action nigel ensure all P1 and P2 issues not closed belong in a
   change proposal

   <trackbot> Created ACTION-264 - Ensure all p1 and p2 issues not
   closed belong in a change proposal [on Nigel Megitt - due

Summary of Action Items

   [NEW] ACTION: glenn to work with pal to resolve edits needed
   for issue-259 comments [recorded in
   [NEW] ACTION: plh to add EBU wording in charter [recorded in

   [End of minutes]

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Guessing input format: RRSAgent_Text_Format (score 1.00)

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Default Present: nigel, +41.22.749.aaaa, tmichel, +1.720.897.aabb, glenn
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Present: nigel glenn tmichel plh pal jdsmith frans_ebu
Regrets: Michael_Dolan_for_first_30-60_minutes Frans_de_Jong_after_first
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Found Date: 16 Jan 2014
Guessing minutes URL: [43]http://www.w3.org/2014/01/16-tt-minutes.html

People with action items: glenn plh

     [43] http://www.w3.org/2014/01/16-tt-minutes.html

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Received on Thursday, 16 January 2014 17:17:02 UTC