nigel: 2 days of meeting
… a lot of different topics to cover
nigel: we have a bunch of documents that we want to progress
… and we haven't begun horizontal review
… a goal is to decide which documents should get to WD to trigger HR
… the new process requires 3 months between WD and CR
… second goal is deciding what to do with TTML3
… 3rd WebVTT
… and 4th MIME types for embedded media
pal: I'd like to resolved on the font file size issue
nigel: we have several TTML2 topics
… I listed CSS properties but I don't know when we will discuss it
… for Danmaku, we will meet the Chinese IG tomorrow
… the schedule is arranged to cover for people departure times
atai: we probably need 45 min for 360
atai: we could have a short slot for demoing
… I would be interested in giving a 5-10min demo
nigel: the schedule does not include anything about charter
… the WBS survey is closed
… do you know if anybody is planning to explain to us about the charter?
atsushi: I have no information from PLH
nigel: [tweaking the agenda]
atai: we could also have followups of the break out sessions to prepare for the next meeting
<gkatsev> M&E IG joint meeting minutes
cyril: how many topics were adressed ?
atai: most of the time we discussed 360
pal: my take away is that there was no objection to support for text in MSE
… no objection, some support but this needs implementation
cyril: Some details to sort out, main problem is native parsing support, TextTrackCue v2
… Want to discuss MSE, DataCue and v2 TextTrackCue.
… Mental model:
… DataCue is the API used to surface events or information contained inband e.g. in an MP4 file
… The major use case is emsg box and metadata in general, not subtitles
… DataCue is how you surface thing
… TextTrackCue v2 is how you pass information in the other direction.
… DataCue flows browser -> app
… TextTrackCue flows app -> browser
Glenn: The native platform could be parsing the inband subtitling then surfacing it as a TextTrackCue if it wanted to.
… The immediate use case is to allow the script to do the parsing by getting data from DataCue or something like that.
… can then be presented.
Cyril: Continuing model.
… The content of the text track does not flow into the app.
… MSE controls the synchronisation and what text track is used and so on.
… The added value is management of buffering and synchronisation more properly.
Pierre: It has more opportunity to do sync more accurately.
Cyril: Because little browser support for TTML, how can you have MSE support for Text Tracks without native support.
… MSE that handles buffering, pre-rendering and synchronisation.
pal: unless it's encrypted, applications can do the extraction
… why do ask browsers to do parsing?
… just do it yourself
nigel: that's based on the model that the raw data that MSE exposes could be an IMSC document
… for example unwrapping mp4 containe
cyril: MSE could do the unwrapping, pass the IMSC/WebVTT doc to the app, the app would create an object and pass it back to MSE
nigel: what about accessibility?
… the BBC player always puts the right attributes on the div that displays the subtitles
… so that an assistive technology would read this out
… we would do adhoc repositioning when controls appear
… I'm trying to think whether any of these proposals would have impact
gkatsev: you can also change the size of the div
nigel: that's not enough to deconflict the UI from the text
nigel: I'm concerned that if you pass it down you don't have controls
cyril: on the other hand, if you pass it to the browser, it can handle PiP, fullscreen, second screen
gkatsev: people who use captions would not want screen readers over captions
nigel: not everybody who can't hear can see
pal: what can this group do?
… that's a media WG discussion
atai: to understand Cyril's model, is the rendering of the cue done by the browser?
atai: this whole makes sense with the improvment about integrated rendering
nigel: the 2 problems seem to have some symmetry
… why audio/video are not treated as subtitles?
pal: if you encrypt subtitles, then there is an issue
… you'd have to discuss how to expose it back or not to the app
cyril: I've never heard of encrypted subs
nigel: the synchronization seems difficult in the browsers
… the DataCue breakout was interesting
… foolip said you misread the time marches on algorithm in the HTML spec
gkatsev: the timeupdate event firing is limited
nigel: I think that spec needs to be updated
… he's view is that the intent was that the time marches on should be run more frequently
… and a good implementation should be able to trigger the onenter/onexit close to the actual time
… Chris Cunningham assigned a Chrome bug to himself
… if you give it to MSE you may have more accurate timing but if the cue events are fired at a better time
gkatsev: I think there is benefit to having that
… but maybe less of an advantage once the time marches on thing is fixed
Cyril: Relying on cue event timing isn't going to be as good as relying on native.
… Implementation is really painful at the moment relying on maintaining synchronisation with timeupdate events etc
gkatsev: In video.js we use timeupdate but we're thinking of adopting RequestAnimationFrame
gkatsev: it's been working fairly well so far
nigel: have we got any request for the Media WG?
gkatsev: we can talk about that with them
… they are all tied together?
cyril: is it a good idea to present my model?
pal: we could discuss separation of work between WICG, TTWG and Media WG
… if it deals with Timed Text format and accessibility
… if it is an API question it's the WICG or Media WG
… that means that if they see a need to extend the formats or accessbility aspects, they should come back to us
… in this group, we will not have sufficient browser vendors representation
… and vice versa
atai: the WICG is the place where the 2 communities would meet
nigel: the WICG allows people to develop micro features without process
atai: any activity yet on the WICG?
pal: Tess took the action item to get that started
cyril: this will be on discourse?
gkatsev: should we discuss that with the Media WG tomorrow?
cyril: yes, I can draft some slides
<gkatsev> WICG discourse
nigel: that was a good meeting, very constructive
… it went better that previous meetings
… there was good progress on all of the issues
… the specs will be updated
… but their feedback was that either we should implement the proposed changes
… or ask someone to do it
gkatsev: we could add tests
nigel: well it was not mentionned
gkatsev: adding tests is good because browser vendors do pay attention to failures in WPT
glenn: what features?
nigel: line alignment (multiRowAlign) and line padding
pal: if somebody cared enough, PR against Chromium or Firefox
… would help
… they care about doing good rendering
nigel: that's where we are with the CSS WG and we should be happy about that
<nigel> CSS Issue 4319
atsushi: this was discussed in JLTF
… it was mentioned that it may have conflicts with boutens
pal: we could say that text emphasis is not allowed on upright text
glenn: they showed examples of prints that had that
… put the emphasis on the tate chu yoko block
atsushi: there is a new property that allows specifying a limit to the number of characters in Tate Chu Yoko
pal: where should the discussion happen?
atsushi: from an HTML and CSS point of view, you should not use TCY for long text
pal: I'm told that in DCinema 4digits years are displayed upright
cyril: Netflix's style guide says do not use combine for more than 2 characters
<nigel> JLREQ issue 109
<nigel> i18n issue 726
<nigel> github: https://github.com/w3c/imsc/issues/484
Nigel: This was discussed in CSS WG and with APA
… there is a view that CSS speech spec is tended for this kind of purpose
<gkatsev> speak css property
Nigel: erika from CSS WG Commented if you set visibility to hidden but speak property ? it is supposed to be sent to the screen reader
… it was not clear from me from the spec that it should behave that way
gkatsev: spec is ambiguous
Nigel: I now think there is something needed
… CSS WG had volunteers to look at it
gkatsev: Currently this is defined in CSS3 speech
nigel: It is a buggy spec
… values for speak property are possibly wrong
gkatsev: The alway value is confusing and needs update
nigel: they may have thought of the difference between visibility and display but it is not clear
… action: we need to wait for the result of the a11y task force
… after we have an outcome we can see what to do next
glenn: in ttml we ended up merging voice-rate semantics into tta:speak
… we have values like normal, fast
Nigel: There is a difference in CSS:
… if you use speech representation that is how it should be styled
Nigel: The idea in for CSS speak that you can direct screen reader for audio representation even if they
… do not have a pixel representation
… I now see that is a retired note in annotation in the spec
Summary: Wait what the CSS a11y TF come up with
<nigel> github: https://github.com/w3c/imsc/issues/472
Nigel: It is about font feature in IMSC 1.1
… Pierre question is about ressource limit
… should processors support a minimum set of font formats
… should @type be limited to a certain set of values?
… should the number of resources be limited in a document?
… should the size (in bytes) of each resource be limited?
… regarding should @type be limited to a certain set of values?
… my recommendation is to not require to constraint @type but the browsers need to support a minimum list of font ressources
… for the start of the spec the limit for the number of ressources my proposal is 2
Nigel: Why should we limit?
pal: Download time
cyril: we could make a difference between the number of ressources in the document
… and the number that should be loaded at begin time
pal: do we have a strategy of effective font loading in ttml
glenn: we have a strategy and named it
… lazy loading in our discussion
… it is an implemenation dependent feature
Nigel: Number of number font elements can be restricted
… you expect each one font element just one font ressource to be loaded
… if you want to restrict it you should restrict number of font element
glenn: I would not like to constraint neither font element nor ressources
… the application can decide on the basis the referenced font information what to fetch
pal: if you use fetch mechanism you can make the limitation bytes
… the downside of fetch it requires full processing of the document
… full processing like styke resolution etc.
glenn: This is a constraint you can only test during presentation processing
glenn: coult it be a constraint in the HRM
… as info: digital cinema sets fetch limit to 10 MB
… spoke with adobe colleague
… this is no coincidence
… it just works there
atsushi: In Japan we provide only a subset of a font
… this limits the size
cyril: I don't think that we at netflix we would do font subsetting
… especially for the first episode you have to provide all
glenn: noto sans font 8.6 mb for simplfied chinese
gkatsev: We can start with 10 MB and then see if anybody is complaining
… in that case we increase the limit
Pal: everybody agrees to have 10 MB as limit
<nigel> PROPOSAL: For FPWD limit fetched font resource to 10 megabytes
<nigel> Nigel: Any objections?
Resolved: For FPWD limit fetched font resource to 10 megabytes
pal: Constraint on @type
… my suggestion no constraint
… but require IMSC to support minimum set of font formats
PROPOSAL: no constraint on @type but IMSC processors need to support minimum set of font formats
<nigel> group: [no objections]
Resolved: No constraint on @type but IMSC processors need to support minimum set of font formats
pal: But...which font format?
<nigel> Nigel: Any objections?
pal: we need to be careful
… there are couple of formats woff woff2...
… I have not the expertise to decide what is hard not hard
cyril: We need one compressed and one uncompressed format
Nigel: There is an example in the DVB spec
<glenn> OTF's SVG table defined at https://docs.microsoft.com/en-us/typography/opentype/spec/svg
Nigel: font download it supports OFF (Open font format) and WOFF
… that is where I would start
cyril: we can discuss about woff2
… it is broadly supported
… and compresses better
<nigel> andreas: It would be good to get a view from Vladimir Levantovsky from Monotype who is a member of this group too.
pal: we wanted to specify requirement of processors
cyril: we should constraint it to not support svg-outline
<nigel> PROPOSAL: Require minimally processor support for font/otf with cff and ttf (i.e. no svg outline) plus woff
Nigel: Any objections?
Resolved: Require minimally processor support for font/otf with cff and ttf (i.e. no svg outline) plus woff
gkatsev: woff2 has 30% better compression (as a data point)
cyril: about unicode range
… I am satisfied with the current solution in Pierres PR
nigel: I have an example with two fonts and different sources
… but overlapping sources
… should we constraint this?
… is there a use case for this?
glenn: Usually we leave it to the implementation what make sense
pal: In this case we constraint the size of fetch ressource
… are we asking the implementation to find out the minimum set need
… seems complicated
glenn: we have font slelection strategy in in TTML2
nigel: this is orthogonal to this discussion
pal: what we can do
… we can forbid different fonts with the same font family
nigel: we may have different fonts and ressources for the same font family because they are for different faces
… e.g. bold, italics ...
Nigel: we can try to constraint font family together with different properties like weight
pal: how do unicode range goes together with fetch
… it needs to be validated by the processor when the size is exceeded
… the typical usecase is one font and one font family, right?
atai: NPO in Netherlands have the requirement to have two fonts in one document (one for Arabic and one for Dutch version of the subtitle)
pal: even if you have two fonts it make sense
… to constraint the combination for ranges, family, style and weight
Nigel: I see two propsoals
… you forbid to have unicode range overlap between different font elements with the same values for font famliy, style and weight
… or to have no constraint
glenn: There may have identical font elements with different kerning tables
pal: you can forbid that
glenn: I would recommend that implementation follow the algorithm defined by css
the HRM should use this algorithm
pal: this would solve that issue
glenn: ttv does some (not all) HRM checking
nigel: You can not specifiy the HRM constraint
… you can not statically validate this as font resssouces may change dynamically
pal: idea of hrm is to provide basic guidlines so things are going to work
<glenn> see https://www.w3.org/TR/2018/REC-css-fonts-3-20180920/#composite-fonts for text on handling overlapping ranges
PROPOSAL: Unicode range overlap between different font elements are permitted even they have identical values for style, family and weight
Nigel: Any objection?
Resolved: Unicode range overlap between different font elements are permitted even they have identical values for style, family and weight
Proposal: Once we merged the open PR we go to FPWD
Nigel: Any objections?
Resolved: Once we merged the open PR we go to FPWD
nigel: [pulls up repo]
nigel: there's a few things we need to cover
… last time we talked about it pal asked for some offical communication from EBU
… they had already done so
… in the reflector
… I've taken on the role of editor
… three docs
… 1. one is normative part
… 2. live carriage
… 3. live extensions guide
… take first two to req and 3rd one as a note
… atsushi: how do you do PR preview in repos with respec to make it easier to review
atsushi: there is a tool for preview
nigel: how to make it work with multiple docs in the same repo?
… maybe pr-preview can be configured
… can you look into it, atsushi?
nigel: currently no PRs or issues against it, only editorial notes
… as a reminder, the scope is for contribution of live streamed subs to distribution encoder
… the idea is not that these extensions would apply to a wide number of users
… if you've got an IMSC distribution encoder with a live distribution mechanism such as HLS or DASH
… this provides a way to get the content to that
… approach taken is to define some extension features
… key things are:
… introduces concept of a sequence with an identifier and number
… to resolve temporal issues
… tt-live is the main specification
… has anyone reviewed it?
atai: I have comments on the basic structure
nigel: let me continue briefly and hear it later
nigel: describes temporal overlap resolution mechanism
… defines processing semantics which are important for usecases in the scnearios of live
… the ability to delay delivery of documents or time within documents
… handling reference clocks
… the ability to hand over between subtitlers
… typicly in a live authoring one person will be subtitling and when they're done they hand it over to another subtitler
… this doc describes how to resolve inputs coming from multiple sources
<nigel> TTML Live Extensions Module
nigel: new constraints attributes on time base, sequenceIdentifier, sequenceNumber, authorsGroupIdentifier, authorsGroupControlToken, referenceClockIdentifier
cyril: what's the difference between stream and sequence
nigel: sequence set of documents with the same identifier
… and a stream is is the delivery of that sequence between two endpoints
… i've defined a profile which is simple
… a little bit from imsc, I've found I've needed as well as the concepts of permitted and prohibited, I needed optional and required
… the profile describes some extension features
… Apendix has requirements for carriage specifications
atai: thank you for you work
… I know there has been several years of discussion to get to this state and several edits
… I know what's in there is all necessary input to solve the problem
… but I also would really like to get this adopted by the market
… the market needs less coplexity
… at the end what the core scenario is the sequence number and everything else is for handler
… to solce the core problem we possibly just need the timing model and the sequence number
… that would be easier to digest for a lot of people
nigel: so, separate out things like hand off?
atai: system model is important but not relevant to everyone
… main usecase is contribution of live subtitles to a streaming encoder
… out of band live captions to the encoder and get delivered via DASH or HLS
… so, less is more
nigel: thank you
glenn: so you're suggesting this is paired down to core normative pieces
glenn: another option is to move all the normative syntactic pieces to the top and move everything to appendixes to the meat of it is at the top
… issue if the top section references the system model it could be confusing
nigel: section 6 is the meat of it
glenn: I thought section 10 was
cyril: annex B is also important
cyril: PDF of tt-live is 44 pages
glenn: under the namespaces section, it was vague whether you were redefining or defining or merely copying from TTML 1
… in general, I don't like copying normative defs if possible
… I see you've changed the prefix to tt:tt
nigel: might be a bug
glenn: having a copy of the normative defs across docs has some challenges, FYI
nigel: I understand concern, not sure I agree
… if I were defining the namespace, it would be a problem. just saying shall be used
glenn: I would put a note that the namespace is defined in TTML and link to it
nigel: I think this is done by reference, but we can adjust it to make more clear
… it isn't claiming to redefine anything
… new vocabulary are below
glenn: xml schema isn't used
nigel: maybe another bug
nigel: xs:string is used
glenn: make a note to say that normative defnitions are found in the appropriate docs
nigel: please raise an issue, it would be good
glenn: the items that have both optional and permitted in the profile section have some overlap
… it's a bit unclear
… both optional or permitted in live handover
nigel: live handover is optional and permitted if it's a handover manager node
glenn: it wasn't clear to me
cyril: maybe make it clearer by saying optional for everything or permitted by handover manager node
glenn: just having OR in there would've alleviated my concerns
nigel: anything else?
pal: I will review and suggest anything further
atai: it isn't about the technical quality
… it's about experience on how people look at long documents
… I think to get the core scenario working, you don't need too much
nigel: I'm definitely happy to hear suggestions on refactoring the document
glenn: I noticed you used SHALL, does IMSC use MUST? We use MUST everwhere
atai: this is a followup from EBU joined meeting in geneva
… one idea was also to align with IMSC
nigel: the way that this is structured is that it's an extension
… previously extension to EBU-TT
… nothing specific to EBU-TT
… by moving here by defining extensions means we can apply to IMSC as well
… so we can have an IMSC live that supports both this profile and IMSC itself
… that would provide a path towards live IMSC
… that's a design goal
glenn: a couple other editorial comments
… I would suggest editing extensions to extension, at the top
… instead of v1, I would suggest just using 1 to match TTML1
… I've been calling other modules timed-text instead of tt
… not tie directly to TTML so IMSC can also use it
… we should pick a qualifier and use it for all modules
… I don't have a huge preference
nigel: any ore on this one of the 3 docs?
glenn: are you read to publish as a working draft?
nigel: this has not been published, it's effectively an editor's draft
pal: to me criteria is whether normative section portions match source EBU doc
nigel: they do
pal: then publish
… just publish today
nigel: and refactor can happen after
<nigel> WebSocket Carriage Mechanism
nigel: next one is carriage mechanism
… one of the features of the main doc is a carriage mechanism
… this specifies how to do it over web socket
cyril: 14 pages
glenn: can we get a sense on whether tt or timed-text
nigel: wanted a brand name that's easy to say: TTML Live
… felt as shortest brand name
glenn: should I go and changed Timed Text to TTML? In say Karaoke
… Timed Text Karaoke or TTML Karaoke?
cyril: one question
… what is the conformance to this document
… is it a node or encoder? how do you verify comformance?
glenn: how do you test it?
nigel: definitions optional required etc translate to a pair of document requires
… and processor conformance requirements
… those permutations are defined by the profile disposition in section 6
cyril: have you thought about CR exit criteria for this?
nigel: well, they are implementation criteria, so, there should be tests for those
… from my perspective, I know 3 implementations
… one open source lead by me
… one is closed source by red beam
… another is closed source by FAB
… closed source can generate docs
… open source and consume and generate docs and output IMSC
… we can certainly contribute back some of the validty tests from the open source
nigel: so the web socket carriage mechanism, it's pretty straight forward
… just iterate thoguh each of the considerations from the main document for carriage and let the web socket do the heavy lifting
… there are certain rules about connection lifecycle and error management that relate to the websocket RFC
… there are some normative provisions that match what ws requires
… any comments on that one?
cyril: so to demonstrate intertop, you'd need a websocket server?
nigel: yes, you would have the normative provisions that if you send an invalid document it would break the connection
cyril: so it's more of a protocol?
nigel: yes, it's a good question how to test this
<nigel> TTML Live Guide
nigel: let's move to the guide
… some may remember that EBU-TT has a lot of discussion and informative text that I've moved to this guide
… some duplication from the main doc but it's all informative
… there are things like time graphs showing results of processing
… how overlaps get resolved
… lots of details that hopefully will help
… some of the things atai asked for examples with copmuted and resolved times
… there's an editorial note to bring to this document
… all of this needs no comformance language but just explanatory text
… all sections say "This section is non-normative"
… any questions on this?
… in response to pal's point earlier, move the first two docs on the req track to move to FPWD
… I'll create PRs based on glenn's issues
… should we go straight to FPWD or have another review period?
… no requirement for quality to go to FPWD?
… this is implemented already
cyril: we don't have much expertise on this in the group
… would be nice to have a wide review
atai: there's a certain amount of people who looked within EBU
… so it's really important to get peer review on this, it should generally be understandable
… specific live scenarions, conditions, etc
… most complicated is the timing model
glenn: I second motion to FPWD
PROPOSAL: go to FPWD for the Live extension module and the carriage mechanism after resolving current open issues
nigel: any objections?
nigel: no objections
Resolved: go to FPWD for the Live extension module and the carriage mechanism after resolving current open issues
nigel: one other thing to bring to attention that may not be obvious
<nigel> Relationship to TTML in RTP
nigel: there is an IETF document about embedding TTML in RTP
… could be seen as a way to do live
… wrote a doc about creating a TT-Live from a TTML doc in RTP and vice versa
… there's some interesting complexity
… tt-live is done from prespective that's all info is in the doc
… in RTP some of the info is in the wrapper
glenn: you used TT-Live
nigel: I should change it to be consistent
gkatsev: using Timed Text may confuse someone thinking it could apply to WebVTT, when it may not
cyril: should we talk wot WebRTC WG?
nigel: they have a req to make live captioning in WebRTC
atai: there are people doing live captioning in webrtc
glenn: some people were talking about this in the M&EIG
… was quite involved in RTC and proposed some subtitles
nigel: how did they do it?
atai: I can find out and tell everyone
glenn: take a look at the minutes, I think there was a presentation
nigel: any other points?
atsushi: do we need a CfC?
nigel: any resolution has a 2 week period for comments
… two ways for resolutions, record a resolution from a call/meeting and timer starts then
… alternatively, a CfC in an email
… when sending minutes out, mention decision period to get objections in
… no need to do both
atsushi: should I wait for 10 days?
nigel: depends on the kind of resolution
… there needs to have some editorial work
glenn: I don't think it should be published until the 10 days
nigel: yes, you need to wait till the decision review period is done
… ttml topic is next
nigel: we have 5 open issues planned for TPAC
<nigel> TPAC labelled TTML2 issues
<nigel> github: https://github.com/w3c/ttml2/issues/945
glenn: the request here is to remove application of ruby position from ruby annotation text
… but to leave it for ruby container text
… right now TTML2 says it applies to ruby container and text
… CSS is not very clear
… the original reason was because you can have text without a text ocntainer
<nigel> CSS ruby-position
glenn: in that case you want to be able to specify position
<nigel> TTML2 tts:rubyPosition
glenn: but you can only have one text annotation present if you don't have a text container
… so you cannot have one that says before and one that says after
nigel: in terms of delta with CSS, CSS says applies to ruby annotation containers
glenn: but a container says applicable to boxes not elements
… "ruby annotation containers are internal ruby boxes"
… there is some ambiguity in the language
cyril: CSS spec is still in WD
glenn: 5 year discrepancies between WD and ED
… the status of CSS specs in this area are not very firm
glenn: what problem are we solving by removing it
pal: let's match CSS
glenn: but CSS has not updated the WD since t5 years
pal: also there is no reason to let it apply to text
glenn: but a text can have a text without text container
pal: there is an implied one
glenn: but there is no way to refer to it
glenn: we could just refer to the definition of ruby test container
… in section 10.2.21.1
pal: ruby position is inherited
… you never need to specify on ruby text
… because you can always specify on the container
… and it is inherited on the ruby text container
atai: from what I understand, the difference between CSS and TTML is that the ruby position can be specified on a different structural element?
pal: no, it's only application
… CSS says it does not apply on text, just text container
pal: removing it from text does not remove any functionality
glenn: that's wrong, because you can specify it on a span ruby=text and it has the semantics of applying to that annotation text or the container that's implied that contains it
… if you removing it, it would not have any effect
nigel: is it true that in order to get the same functionality if you don't allow on text, you'd have to create an explicit text container?
pal: you can specify it on the ruby element, and it will inherit to the implied ruby text container
glenn: that doesn't deal with content already fielded that is putting ruby position on ruby annotation text elements
pal: in the order of priority, it is not the most important feature
glenn: do you agree that if we remove the ability, we are breaking content?
… it does make a technical change
atai: we do not need a resolution today
… but we should agree to align with CSS whenever possible
cyril: it's difficult to align with something not stable
nigel: should we tell CSS to do the way we do it?
atsushi_: i18n and CSS is working on updating the CSS spec
… to finalize the element structure
glenn: it's not the structure in this case, but on the property
nigel: if this work changes the element structure this would have an effect
glenn: I doubt it would change the element structure, just the style definition
nigel: does that mean we have a place to contribute this idea?
atsushi_: current HTML does not have rtc
… that may be why there is a difference
nigel: if they did not have a rtc, how do they apply ruby position
atsushi_: they do it on rt
nigel: we should get alignment with CSS by having them apply it to rt
nigel: anybody wants to take the action?
atai: do you want to wait until the i18n work is finalized?
atai: makes sense to me
glenn: I will file an issue with the CSS WG
atsushi_: we want to intrduce rtc and tabular ruby
… if we do that, it might be easier for every one
atai: as a group, we should align
cyril: we should make sure TTWG, CSS and I18N are all discussing the same thing
<nigel> Action on Glenn
<nigel> SUMMARY: Issue not time critical for us, work alongside CSS and i18n to get an aligned solution across TTML and CSS.
<nigel> github: https://github.com/w3c/ttml2/issues/950
glenn: after discussions, I said we could remove it
pal: I think it was added as an error when going from TTML1 and TTML2 and so it should be removed
glenn: we could not remove set and not remove animate
nigel: Pierre says is an editorial and Glenn says it can't be tested
pal: it was introduced by mistake and we should remove it
glenn: I assume it was not an accident
… if we cannot test the removal, why remove it given the editorial pain
pal: the goal was not to create a divergence between TTML1 and TTML2
… it's only a spec divergence
… I checked the differences in algorithms in TTML1 and TTML2 and this one stood out
glenn: it's a change in a normative section
cyril: can we ask to go through the editing work to see if there is any problem?
glenn: I think we have done that
… and I said I am ready to remove them
pal: let's keep the issue open
SUMMARY: defer this for the time being and don't make this a dependency for TTML2 2nd edition, removed from the milestone
nigel: in practice right now they are the same
cyril: in this case, example 2 and 3 should give the same result?
… but if this was CSS it wouldn't be the same
… example 2 the textDecoration would be displayed
… example 3 is not possible in CSS because there are no values equivalent to no*
… you just can't do it
… once underlined has been applied at a parent level, you cannot un-apply it
glenn: in TTML, it does punch a hole
pal: is none identical to specifying the 3 no*
cyril: at least we need a note that none here behaves differently from none in CSS
glenn: the no versions are also different
cyril: because you can undo them and not in CSS
… this is a feature where we are diverging from CSS
… that does not mean you cannot map TTML to CSS
pal: it is not inherited in CSS
nigel: the only way to get rid of the text decoration is to use an inline block
nigel: we need a note to explain that none is equivalent to no*
… and in the semantic derivation that there are differences (inheritance behavior
glenn: we could put it directly in the text decoration definition
pal: 2 different notes: TTML-level and CSS/TTML difference
SUMMARY: we agree with having 2 notes, and let the editor decide where they go
pal: the problem is that the constraints are expressed based on properties not elements
… so you cannot validate them until you are in an ISD
… we have spans that behave like elements
… there are 3 options: we can say validation is done after ISD; we can constrain the application of a style resolution such that you can validate before style resolution; or say it was a mistake and change it to elements
glenn: I prefer option 1
pal: condition has a problem that we don't have a model that says when it's executed
nigel: there is no disagreement that has to be after ISD construction
pal: this requires a huge change in IMSC.js
nigel: there are 2 ways you can modify a property, but set/animate or by initials
glenn: the PR makes them non animatable
glenn: in TTT it validates after ISD construction
pal: what I would like is them to be elements
cyril: it's too late
pal: the way it is specified today is terrible
nigel: I don't see any advantage in making them not alterable by initial
… the conditional one has also some problems
pal: yes, conditional has other problems
nigel: the answer to the question in the issue, is yes that is the intent
cyril: should we close the issue with no change?
glenn: do we want to let the initial change the initial value from none to ruby?
cyril: it's up to authors not to do crazy things
glenn: I'm ok with that
Resolved: we close the issue with no action
<nigel> SUMMARY: Yes. we confirm that validation of ruby constraints can only happen after ISD construction.
nigel: I had a philosphical debate about "determine"
pal: I prefer "determine"
glenn: I can take out the cd/m2 unit
glenn: the other comment I'm not sure it's good
pal: fine, you can ignore it, it is not that important
SUMMARY: Glenn to update the PR to remove the extraneous units and Pierre to approve, and Glenn to merge
nigel: looking at the issues, can we move to FPWD ?
… there are 10 open substantive ones
… 5 issues without PR open
pal: the goal of FPWD is to get to HR started
nigel: this is a REC document, the path is not to go to FPWD
[looking at process]
pal: we can just ask people to do HR on the ED
glenn: can we make changes after HR has started?
… so I need to prepare a list of changes?
SUMMARY: Glenn to prepare list of changes (editorial and substantive changes) and Nigel to initiate horizontal review based on Editor's Draft
Cyril: There are a number of open issues
Cyril: To start with the requirements, that's in tt-reqs issue 9
… Reminder: we began working on these requirements first. Reviewing them:
… 2 types:
… 1. To add more semantics to a document to be processed independently of the styles, which may or may not be in the document.
… Important - you can go deeply into details like the trajectory of the bouncing ball.
… Can get very verbose for each event individually.
… Netflix wanted to specify timing first then secondarily styles that could be in the document or overridden by the presentation processor.
… For example to allow Netflix to use the same style bouncing ball for all shows.
… At the same time, allow for specific styling in the documents if you like.
… That's how we proposed the requirements initially.
… Then the explainer lists possible solutions. [iterates through the options in the document]
… Using animate increased the verbosity of the representation.
… After this we proposed the current spec.
… The feedback initially was that using new elements was not a good idea.
… What I tried to do for the first version was see what the minimum amount of new attributes is to meet the requirements.
… I also wanted to do the minimum to keep compatibility with IMSC 1.x
… Does it make any difference if the features are expressed as new elements or new attributes?
Pierre: What's the most efficient? Using ruby as an example, introducing an element would have been much better.
… I don't have a strong opinion a priori.
Cyril: The specification starts with a model, which is kept simple.
… Imagine a small section of a movie with a song where karaoke mode is needed.
… Or another example is the whole document only represents that song.
… The first approach is a karaoke attribute in some namespace.
… The intention was to specify that here in this section the semantics of karaoke apply and the processor can do its thing.
… Then you need to know what can be overridden.
… That is given by the karaokeMode attribute and the set element to provide the inner times within the karaoke.
… The karaokeMode tells you what kind of change to do, e.g. color, which changes the color of the text with the time.
… For example a color sweep.
Glenn: The default for karaokeMode is auto so the processor can do its own thing
Cyril: [shows example from the draft spec]
Nigel: Where do the end times in the comments derive from?
Cyril: Only one karaoke can be in progress at any time so that sets the limit on some of them.
Nigel: [interested that the timing model seems different]
Cyril: Shows second example with karaokeMode="emphasis"
… No details of how the animation happens such as bouncing or moving horizontally.
… The only thing given is the key times.
Glenn: That's not adequate here because the balls need to be removed after each animation.
Cyril: That's not the intent, it is that the processor will do a first pass on the entire karaoke section, see that the mode
… is emphasis all the time and then see how it can be applied.
… There's only one glyph at a time that has the animation, is the assumption.
… 3rd example, has both begin and end times.
Glenn: Problem here is we can't use animate to vary a discretely animatable style.
Cyril: Two levels. First is only one key time per word. Second is two key times per word. I used set for the first and animate for the second.
… Two attributes: one to turn on karaoke mode the other to set the type.
… There's a style property for setting the image for the emphasis, called imageEmphasis to mimic textEmphasis.
… Now looking at the issues.
… Glenn sent several editorial comments.
… One comment was the same as Andreas's comment, which is that there are very few normative behaviours in the spec.
Cyril: The idea is that an implementation that does not support the karaoke mode can just skip it.
… If you ignore it then it's a regular timed text file.
… Second level is you understand the timing and do whatever processing.
… Third level is precise rendering details, which has more normative requirements.
Glenn: [shows possible representations]
Cyril: First one is setting the colour by span, can be done in IMSC today.
… There's no information that it is a karaoke animation to allow processor to override styles.
Glenn: You could use ttm:role="lyrics"
Pierre: There's nothing defined.
… [shows sweep version with colour sweeping through glyphs]
… You cannot do this in TTML2 today because there's no way to apply a colour gradient linearly across an offset.
Cyril: It's not a Netflix requirement to define this exact feature because the renderer will apply the style itself.
Glenn: Example of simple linear text emphasis. [shows example of ball moving across the top of the text]
… This is different than our current textEmphasis because currently it applies to individual glyph areas.
Cyril: You might be able to discretely set the textEmphasis on a character by character basis.
… It wouldn't be continuous.
Glenn: That's one kind. Another uses a bouncing ball [shows example with orange bouncing ball combined with text colour sweeping through]
… Another, discrete turning on of outline. You could do this today with IMSC1.
… Last one does outlines and animated font size in the vertical direction.
Pierre: A key question, first order, is what is the right first order, is it semantic?
Cyril: Semantic and timing.
Pierre: Is that right or also is it necessary to capture the actual visual style.
… To me the first one is a no-brainer. The second is not obvious to me because the karaoke styles are used in
… popular movies and are incredibly complex and high quality.
… How high fidelity do we ultimately want to get to beyond this in TTML.
… Branding is a much bigger topic.
Glenn: I've been talking about a slightly different syntactic variation of doing this with Cyril. In this variation I proposed
… using a single karaoke element that is treated as an Animation.class element like set and animate but with
… special features, for example it does not take style properties but takes color, emphasis or outline, which define
… karaoke effects. One of their values can be auto.
… If you want all of them to be auto you set auto="all"
Cyril: We don't need to look at the details, but can look at the two options and see what goes in the draft.
Glenn: First order, we could just define some semantic element like this, or abbreviated further.
… Then the question is what do we do second order.
… If we only define the semantic element to start with, then that kind of makes it difficult to test. You can't test anything
… interoperably e.g. by generating a sample image.
Pierre: Often you've argued in favour of under-specifying in TTML.
Glenn: That's because we had XSL and CSS for semantics
Cyril: One way to test is if we stick to the minimal key times and semantics implementation without style, is to look at
… the transitions, take the first rendering and subsequent ones and the differences should happen at the key times.
Nigel: Is there any documentation of karaoke semantics elsewhere that we should be referencing?
Glenn: There's ASS and a rich application called aegisub used for fan-subbing.
Nigel: That's not specific to karaoke.
… It's the place to go for burning text!
Pierre: At some point we will need to think if we can do those semantics in TTML
Cyril: The question is how to define timing in the first version that is extensible later with styling.
Pierre: Excellent question. Is the goal to expand karaoke mode with more detailed color handling, say?
Cyril: Could be something like that where each extra detail can be ignored by older processors.
… The marker method doesn't force creation of spans.
Pierre: My initial reaction is that this draft is consistent with the timing model and syntax.
… Sounds good to me, not to invent something new.
Glenn: I'm concerned not to proliferate and add a lot of new style properties.
Pierre: Why is that? Here, what I like is that Cyril's example is basically TTML and it looks like it.
Glenn: This [alternative] does too.
Pierre: No it has a karaoke element that I've never seen before. The difference is that Cyril's way is still TTML.
… This is just my initial take.
Cyril: We need to see the proposal, study the merits, see how to merge them, choose levels etc.
… I'd like to discuss timeline wrt IMSC 1.2. I think that when we start doing HR on Karaoke a lot of people will have
… something to say.
Pierre: Is there an initial implementation?
Cyril: No, I have a generation tool but not a rendering tool.
Pierre: What Glenn is proposing sounds substantially the same as Cyril's proposal except with a new element.
Glenn: In my alternative just one new element and no new attribtues.
… It is an independent level that can be ignored.
Pierre: In capability are the two substantially similar?
Glenn: Cyril's draft doesn't allow multiple effects at the same time.
… There's no parameterisation and if you wanted to do it then you'd need to do something like what I did.
Pierre: One strategy is to send the existing draft to review and see what the reactions are.
… People might look at it and suggest tweaks or say it's entirely terrible.
Glenn: You'd have to take the animate out and replace it with a set so it doesn't break the semantics.
Nigel: Can't you set calcMode to discrete?
Glenn: They become the same thing.
… Another thing is I allow for nested karaoke.
Cyril: I don't want to discuss merits but timeline and ways forward.
Pierre: If the two options were not that far apart then we could go to FPWD with this and see where we are.
Glenn: Asking for this before we have done our homework is too soon. Cyril and I aren't even on the same page yet.
Pierre: The challenge is to set a roadmap for evaluating and publishing FPWD
Nigel: Why did you want to mention IMSC 1.2 before Cyril?
Cyril: I want this to be in IMSC 1.2
Nigel: It's too late
Pierre: There's no chance.
Cyril: I'm not pushing for wide review today. Maybe in a month if we've got something acceptable to the group.
Nigel: Tying to 1.2 doesn't help, there could just as easily be a 1.3 later that we add this to.
Cyril: We will have people asking for flames and other effects.
Glenn: I'm nervous about going out with a proposal that doesn't have any rendering semantics defined in it whatsoever.
Pierre: You could test transition timings as Cyril suggested above. We've had vague semantics before.
Glenn: I agree, you could do that, is that enough to answer people's desire?
… I know Andreas's comment is about the amount of normative requirements.
Cyril: Can we agree to have a level zero for timing and semantics only and a level one that is more fleshed out in terms of styles and properties?
Glenn: That's possible, and would satisfy your first level requirement.
Nigel: If you don't specify level 1 at the beginning then don't expect anyone ever to implement it, because the level 0
… processors might be all that anyone ever supports.
Pierre: I think it's useful to have something rather than nothing. Having a level 0 is a big win all by itself.
Cyril: The first question is level 0 and level 1. Nigel's point is heard that the incentive to go to level 1 for implementers might be limited.
… The next point is if we focus on level 0 what is the best way to specify timing information?
… a. aegisub marker style showing key times
… b. force creation of spans and then put elements like set/animation/karaoke in it.
Glenn: You can think of the karaoke element being like a marker.
Cyril: My question is do we want to force creation of <span>s or not?
Glenn: I see, do you want a p with elements interspersed in it to signify state changes?
Glenn: I'm uncomfortable with that, it's like going back to the old escape sequences and gets away from structured content.
Cyril: You could say the same for <br/>
Glenn: It is considered a control code.
Cyril: There's precedent then.
… But there's no Unicode character for turning a karaoke effect on.
… If we did this we wouldn't have structured content anymore.
Cyril: My draft does add spans.
Glenn: I don't mind a new thing like set or animate
Pierre: You've not demonstrated clearly why a new element is needed.
Glenn: The problem is indicating karaoke semantic by default.
… One way is, let's say we define a karaoke color and emphasis property, defined at first as auto or none, then you could
… use a set to turn them on at a particular time, and then the implementation does its thing. How does that sound?
Cyril: I thought about it. The problem was you end up having to repeat the same properties multiple times. Maybe we
… can make it more efficient by using style referencing.
Glenn: I'm hearing no new element?
Nigel: I'm hearing, If you need a new element, then explain why
Glenn: I can come up with an alternative solution.
Cyril: Can we come up with a schedule for FPWD?
Nigel: I don't mind either way
Glenn: How about we target 1 Nov?
Cyril: Sounds reasonable to me
Glenn: I have a repository, I will populate it with a draft spec whose content will be the old TTML2 work that we took out.
… I'm interested to know if we have enough implementation intent.
Cyril: It's not very high in my priority list.
… Initially I didn't intend a module for CJK, but just to clarify the edge cases in TTML2.
… We left a lot of cases undefined, like line breaks in ruby, so I'm not sure we need a module.
… If we want new features, yes, but not for clarifications.
… In both cases we need coordination with CSS and i18n.
Glenn: In both cases I don't see the need for @@@@
Cyril: Ruby has been used a lot, especially in Japanese, I don't know about other languages, and bopomofo.
Cyril: Or pinyin.
Glenn: Any kind of annotation.
Cyril: I don't know about roman character annotation
Glenn: We have some open issues about using non-CJK ruby text for example right now we've defined it so you separate
… by adding space in and then do alignment.
… Question is are there open issues for TTML2 2nd Ed right now and my answer is no. Let's push that out.
Cyril: We can let people know that there's a small window of opportunity to review edge cases, but they have to do it
… very soon.
Glenn: Nobody has done that so far. I can put that document out and see where it goes.
Cyril: I'm fine with that so it doesn't get lost.
Glenn: It would give us something to talk about with the CSS folk.
Nigel: So no particular time driver for this work.
Cyril: We haven't discussed TTML3 .
Nigel: Nor 360 and AD profile.
Cyril: What is your opinion about TTML3?
Pierre: It's not on the roadmap, we haven't talked about it.
Nigel: I don't see the need for it because we can add features in extension modules. I don't see any need for
… a change that drives a major version update.
Glenn: I agree, if we do modularisation then there's no strong need for it right now.
… There are a couple of things to change in TTML2 to effectively use the extension modules.
… Right now if you add a new content element in an extension module, say a new element to Animation.class,
… the language in TTML2 doesn't give you that opportunity.
… In other cases we added "or extension modules" but in the case of the vocabulary groups we still have them tied
… concretely to TTML2. We need to add some extensibility hooks - see ttml2#1160.
Cyril: Coming back to TTML3...
Glenn: The reason was to bring in modules, but now that's coming into TTML2 we can put it on the back burner, unless
… there's some other substantive change we find we need.
Pierre: If we decide to go down that path we should retire the ED, because TTML3 returns a result in Google.
… Make a boiler plate to remove confusion, by saying "this is not being worked on"
Cyril: I agree.
Pierre: Just so noone starts implementing it.
Nigel: +1 to banner on the top, we should not relinquish TTML3 and let someone else step in!
Pierre: I want to talk about TTML1 3rd Ed Errata because of XML 1.1 obsoletion.
Cyril: I want to talk about two requirements, one for inline image integration and the other for responsive timed text.
Pierre: There's nothing to do until they obsolete XML 1.1
Nigel: No that's the wrong way around. We want to say "don't obsolete XML 1.1 until we've changed the refs".
<glenn> New issue on ttml3 repo to indicate status as "on hold": https://github.com/w3c/ttml3/issues/34.
Nigel: The sooner we publish the errata the sooner they can go ahead.
<glenn> Github: https://github.com/w3c/ttml3/issues/34
Pierre: Create an issue on TTML1 3rd ed
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Atsushi: I will learn how to publish the errata, and will go ahead and find out.
Pierre: If someone creates an issue and assigns it to me I will prepare the text of the errata
Cyril: There has been no progress, so nothing to do here for now.
Nigel: I agree
Cyril: I raised it and haven't had time to work on it.
Nigel: I said I'd support, but same here.
Cyril: What's the status here?
Nigel: I think private use area in Unicode might work but nobody will thank us for it, and it would have huge workflow issues.
Cyril: Glyph substitution would work much better though.
Nigel: So have a specific font that specifies a glyph substitution for a word, and if you don't want to do that, use a different font?
Pierre: I'm interested in high fidelity generally, but not for IMSC 1.2.
Cyril: We should create specific examples using glyph substitution.
Pierre: I'm also thinking about the high fidelity branding requirements such as the BBC's red line by the text.
Nigel: With the animation
… My secret plan is a mid-summer workshop to figure out how we're going to do this.
Nigel: You have other interested people?
Pierre: Yes, other people have the same use case. It's also tied up with picture in picture, sign language etc.
… We need to figure out what we want to do.
… My personal plan is to come up with requirements by mid-next-year.
Nigel: I think I submitted our BBC requirements already
Nigel: I did this CSS tunnelling requirement because BBC folk showed that you could do BBC branding with CSS already but it's hard in TTML.
Pierre: What about SVG?
Nigel: I'm sure you can get even more precision with SVG
… Maybe use CSS content insertion where the content is SVG, if that's allowed?!
Nigel: This timeline was really useful for us last year. Atsushi, could you try to do something similar for our current
… in progress specifications?
Nigel: You'll have lots of detail questions for us, which is fine, please go ahead and ask!
Nigel: To summarise today's resolutions:
… IMSC 1.2 - agreed to publish FPWD
… TTML Live Extension Module - agreed to publish FPWD
… TTML2 2nd Ed - agreed to publish CR
… TTML Karaoke Extension Module - agreed to try to get to an ED suitable for FPWD by 1st November
… TTML CJK Extension Module - agreed to put a draft together, no particular timeline for publication
… Tomorrow we will look at WebVTT, 360º and AD Profile.
… TTML3 - we agreed to put this on hold for the time being
Atsushi: I wonder if there are missing TTML modules?
Glenn: if so, nobody has proposed them yet
… TTML Live WebSocket Carriage Mechanism - agreed to publish FPWD
Pierre: Don't forget TTML1 3rd Edition errata.
Nigel: Of course, we agreed to create and publish them.
Nigel: And with that, today's agenda is complete so we'll adjourn until tomorrow. Thanks everyone!
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Maybe present: atai, atsushi_, github, Glenn, nigel, others, pal, Pierre, PROPOSAL, Summary