Re: Objections to TPAC resolutions on IMSC1.1

Hi Glenn,

> > Netflix has proposed adding [IMSC1 extension definitions] to TTML2 with no modifications

Do you remain opposed to this approach?

Best,

-- Pierre

On Mon, Nov 27, 2017 at 6:04 PM, David Ronca <dronca@netflix.com> wrote:
>
>
> On Mon, Nov 27, 2017 at 3:34 PM, Pierre-Anthony Lemieux <pal@sandflow.com>
> wrote:
>>
>> Hi David,
>>
>> Thanks for sharing your thoughts.
>>
>> > Netflix has proposed adding them to TTML2 with no modifications
>>
>> At least participant indicated he would strongly object to this
>> approach during the F2F.
>
> Then we need to get the objections and specific concerns on the table so we
> can have a discussion towards resolution.
>>
>>
>> > This is exactly what we have proposed.
>>
>> In the case of itts:forcedDisplay, the changes proposed by Netflix are
>> drastic in syntax.
>
>
> Setting aside itts:forcedDisplay for the moment, what about ittp:ActiveArea,
> ittp:aspectRatio, itts:fillLineGap, and ebutts:multiRowAlign? These are not
> significant technical issues, assuming that TTML2 is updated to support the
> equivalents.
>
>>
>> > We believe that it is better to define the equivalent tts:multiRowAlign
>> > in TTML2 rather than reference the EBU spec.
>>
>> Can you expand on why Netflix believes it is better? This may help
>> folks change their position.
>
> Because we will have a single upper spec, TTML2, for which we profile down
> to a manageable subset for IMSC1.1.  That is a clean model.  Referring to
> EBU-TT for a single feature seems unnecessary.
>>
>>
>> Best,
>>
>> -- Pierre
>>
>> On Mon, Nov 27, 2017 at 3:24 PM, David Ronca <dronca@netflix.com> wrote:
>> > Andreas Tai wrote:
>> >> We found resolutions in the f2f meeting on 2017-11-09 and 2017-11-10
>> >> based
>> >> on the consensus principle. These resolutions represent
>> >> already a compromise. With the formal objections we are now back to
>> >> zero
>> >> and need now come again to resolution by the
>> >> consensus principle in our next meetings.
>> >
>> > The F2F established an IMSC1 baseline; a reference point for the next
>> > round
>> > of discussion.  We have moved that forward with our objections, that
>> > were
>> > accompanied with specific recommendations for the spec.  We are not back
>> > to
>> > zero.  We now have a very specific set of issues and proposals that can
>> > be
>> > discussed.  If we can work through our concerns, then we will have a
>> > strong
>> > consensus.
>> >
>> > Pierre wrote:
>> >> for any IMSC 1.0.1 extension adopted by TTML2, semantics and syntax
>> >> should be modified as little as possible to avoid additional testing,
>> >> training and unintended divergence
>> >
>> > This is exactly what we have proposed.  For the 4 IMSC features that are
>> > not
>> > currently covered by TTML2, Netflix has proposed adding them to TTML2
>> > with
>> > no modifications, and we have also volunteered to take on this work.
>> >
>> >> working with EBU to integrate features such as ebutts:multiRowAlign
>> >> in TTML2 is an opportunity to coordinate with an important adopter of
>> >> TTML, and reduce the potential for divergence.
>> >
>> > We believe that it is better to define the equivalent tts:multiRowAlign
>> > in
>> > TTML2 rather than reference the EBU spec.
>> >
>> >> organizations that have recently adopted IMSC1 might lose confidence
>> >> with the TTWG process if IMSC 1.1 deprecates all IMSC1 extensions and
>> >> replaces them with substantially different alternatives
>> > Netflix is such an organization, having recently adopted IMSC1.  I also
>> > expect that we currently have the largest IMSC1 asset library.  We don't
>> > take these changes lightly, but do so looking forward.  The real
>> > implication
>> > of deprecated features is that at some point in the future, in some
>> > future
>> > version of the spec, the deprecated features will no longer be supported
>> > in
>> > that version of the spec.  IMSC1.01 processors will exist for as long as
>> > there is a business case for them, and the translation from IMSC1 to an
>> > IMSC
>> > 1.1 that is fully a TTML2 subset is trivial.  Lastly, feature
>> > deprecation is
>> > a normal part of technology development, and certainly not new to W3C.
>> >
>> > On Mon, Nov 27, 2017 at 11:09 AM, Glenn Adams <glenn@skynav.com> wrote:
>> >>
>> >>
>> >>
>> >> On Mon, Nov 27, 2017 at 11:59 AM, Pierre-Anthony Lemieux
>> >> <pal@sandflow.com> wrote:
>> >>>
>> >>> Hi all,
>> >>>
>> >>> >> - IMSC1 has been adopted and deployed for interchange between
>> >>> >> multiple
>> >>> >> parties, whereas TTML2 has not
>> >>> > False.
>> >>>
>> >>> IMSC1 is a REC, which is referenced by multiple specifications,
>> >>> including ISO/IEC 23000-19, SMPTE ST 2067-2, ATSC A/343, and DVB A174.
>> >>>
>> >>> IMSC 1.0.1 is a Candidate Recommendation.
>> >>>
>> >>> TTML2 is a Working Draft.
>> >>>
>> >>> > But this has been the plan all along, so such organizations are
>> >>> > either
>> >>> > misinformed or not following the work of the TTWG.
>> >>>
>> >>> For TTML2 to be successful, TTWG needs to satisfy user needs, not its
>> >>> parochial interests.
>> >>>
>> >>> > Any resolution is subject to a period of at least two weeks to
>> >>> > obtain
>> >>> > confirmation from member organizations.
>> >>>
>> >>> I am not disputing the right for members to object to a resolution. I
>> >>> am disputing the assertion that "I cannot recall any formal objection
>> >>> to the synonym/alias proposal requested by Netflix". This assertion
>> >>> cannot be true since there was no opportunity for formal objection at
>> >>> TPAC since there was consensus on the resolution.
>> >>
>> >>
>> >> I do not agree. There was not a consensus, since we explicitly noted at
>> >> the time that an opportunity must be given members to consider the
>> >> matter
>> >> (and that they had 2 weeks to object).
>> >>
>> >> A consensus does not exist.
>> >>
>> >>>
>> >>>
>> >>> Best,
>> >>>
>> >>> -- Pierre
>> >>>
>> >>> On Mon, Nov 27, 2017 at 10:45 AM, Glenn Adams <glenn@skynav.com>
>> >>> wrote:
>> >>> >
>> >>> >
>> >>> > On Mon, Nov 27, 2017 at 11:03 AM, Pierre-Anthony Lemieux
>> >>> > <pal@sandflow.com>
>> >>> > wrote:
>> >>> >>
>> >>> >> Hi Nigel et al.,
>> >>> >>
>> >>> >> I do not believe it is possible to fully capture the interactive
>> >>> >> and
>> >>> >> in-person discussions that led to the consensus resolution adopted
>> >>> >> at
>> >>> >> TPAC. Nevertheless, based on my notes, below is additional
>> >>> >> information
>> >>> >> that was shared by at least one member (not necessarily me) during
>> >>> >> these discussions:
>> >>> >>
>> >>> >> - for any IMSC 1.0.1 extension adopted by TTML2, semantics and
>> >>> >> syntax
>> >>> >> should be modified as little as possible to avoid additional
>> >>> >> testing,
>> >>> >> training and unintended divergence
>> >>> >
>> >>> >
>> >>> > We are not considering the adoption of non-TTML features in TTML2.
>> >>> > We
>> >>> > are
>> >>> > defining core functionality that we have been discussing for some
>> >>> > time
>> >>> > now,
>> >>> > before the creation of either IMSC1 or IMSC1.0.1. Nevertheless,
>> >>> > there
>> >>> > is a
>> >>> > general agreement that common features should have similar
>> >>> > semantics.
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> - given the objective of aligning TTML and CSS, TTML2 can delay
>> >>> >> adoption of features in its namespace for which there is no CSS
>> >>> >> equivalent but for which industry extensions exist, e.g.
>> >>> >> ebutts:linePadding,
>> >>> >
>> >>> >
>> >>> > Given that such an addition to CSS would require years to obtain in
>> >>> > a
>> >>> > REC,
>> >>> > it is entirely impractical to use this rationale with TTML2 (and
>> >>> > probably
>> >>> > TTML3).
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> - organizations that have recently adopted IMSC1 might lose
>> >>> >> confidence
>> >>> >> with the TTWG process if IMSC 1.1 deprecates all IMSC1 extensions
>> >>> >> and
>> >>> >> replaces them with substantially different alternatives
>> >>> >
>> >>> >
>> >>> > But this has been the plan all along, so such organizations are
>> >>> > either
>> >>> > misinformed or not following the work of the TTWG.
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> - IMSC1 has been adopted and deployed for interchange between
>> >>> >> multiple
>> >>> >> parties, whereas TTML2 has not
>> >>> >
>> >>> >
>> >>> > False.
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> - working with EBU to integrate features such as
>> >>> >> ebutts:multiRowAlign
>> >>> >> in TTML2 is an opportunity to coordinate with an important adopter
>> >>> >> of
>> >>> >> TTML, and reduce the potential for divergence.
>> >>> >
>> >>> >
>> >>> > Adopting non-TTML vocabulary is contrary to the original
>> >>> > requirements
>> >>> > documented by TTAF1 for use in TTML.
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> > Given that I cannot recall any formal objection to the
>> >>> >> > synonym/alias
>> >>> >> > proposal requested by Netflix,
>> >>> >>
>> >>> >> There was no opportunity to raise formal objections during the TPAC
>> >>> >> meeting since the resolution was adopted by consensus.
>> >>> >
>> >>> >
>> >>> > Any resolution is subject to a period of at least two weeks to
>> >>> > obtain
>> >>> > confirmation from member organizations.
>> >>> >
>> >>> >>
>> >>> >>
>> >>> >> Best,
>> >>> >>
>> >>> >> -- Pierre
>> >>> >>
>> >>> >> On Fri, Nov 24, 2017 at 9:13 AM, Nigel Megitt
>> >>> >> <nigel.megitt@bbc.co.uk>
>> >>> >> wrote:
>> >>> >> > All,
>> >>> >> >
>> >>> >> > This is a situation in which we do not currently seem to have
>> >>> >> > consensus.
>> >>> >> > It
>> >>> >> > appears that two camps exist, with mutually incompatible visions
>> >>> >> > for
>> >>> >> > how
>> >>> >> > the
>> >>> >> > IMSC 1.1 and TTML2 specifications should incorporate some
>> >>> >> > features.
>> >>> >> >
>> >>> >> > Be reminded that W3C consensus means we have to find a solution
>> >>> >> > that
>> >>> >> > everyone can accept, even though it might not be the one that
>> >>> >> > everyone
>> >>> >> > thinks is the best alternative.
>> >>> >> >
>> >>> >> > To summarise the technical issue as I understand it:
>> >>> >> >
>> >>> >> > * IMSC 1.0.1 includes extensions not in TTML1, defined using
>> >>> >> > syntax
>> >>> >> > in
>> >>> >> > namespaces not defined by TTML1
>> >>> >> > * We want to support the requirements met by those extensions in
>> >>> >> > IMSC
>> >>> >> > 1.1
>> >>> >> > * We want to support the requirements met by those extensions in
>> >>> >> > TTML2
>> >>> >> > * We want IMSC 1.1 to be a subset of TTML2 – there are varying
>> >>> >> > degrees
>> >>> >> > of
>> >>> >> > strength about this amongst the group members, i.e. some want all
>> >>> >> > non-TTML2
>> >>> >> > features to be deprecated, others are happy to continue with
>> >>> >> > non-deprecated
>> >>> >> > extensions.
>> >>> >> > * It is important to some (maybe all) members that IMSC 1.1
>> >>> >> > processors
>> >>> >> > be
>> >>> >> > able to process IMSC 1.0.1 documents
>> >>> >> > * We discussed but rejected creating an IMSC 2 that is a pure
>> >>> >> > subset
>> >>> >> > of
>> >>> >> > TTML2 and does not natively support IMSC 1.0.1
>> >>> >> > * It is important to some (but not all) members that TTML2
>> >>> >> > defines
>> >>> >> > all
>> >>> >> > features in its own namespace
>> >>> >> > * The idea of adopting extensions into TTML2 and making them
>> >>> >> > features
>> >>> >> > with
>> >>> >> > no change to their existing namespace was discussed but not
>> >>> >> > adopted.
>> >>> >> > There
>> >>> >> > was a formal objection on the grounds that all TTML features must
>> >>> >> > be
>> >>> >> > defined
>> >>> >> > in the TTML namespace. There was also a process point that we
>> >>> >> > would
>> >>> >> > need
>> >>> >> > to
>> >>> >> > seek permission from EBU for inclusion of EBU namespace
>> >>> >> > extensions.
>> >>> >> >
>> >>> >> > During the TPAC 2017 face to face meeting (minutes) we resolved
>> >>> >> > one
>> >>> >> > of
>> >>> >> > two
>> >>> >> > approaches for each feature:
>> >>> >> >
>> >>> >> > 1. In TTML2: include a new feature in a TTML namespace. In IMSC
>> >>> >> > 1.1:
>> >>> >> > deprecate the IMSC 1.0.1 extension AND include the TTML2 feature
>> >>> >> > AND
>> >>> >> > provide
>> >>> >> > a mapping from the deprecated extension to the new feature.
>> >>> >> > 2. In TTML2: do not include a new feature. In IMSC 1.1: include
>> >>> >> > the
>> >>> >> > IMSC
>> >>> >> > 1.0.1 extension.
>> >>> >> >
>> >>> >> > Netflix has objected to some of those resolutions within the WG's
>> >>> >> > review
>> >>> >> > period defined under the Decision Policy in the Charter. I have
>> >>> >> > received
>> >>> >> > no
>> >>> >> > other objections within that period (which expires at the end of
>> >>> >> > the
>> >>> >> > working
>> >>> >> > day today, California time). I have updated and where necessary
>> >>> >> > reopened
>> >>> >> > the
>> >>> >> > relevant GitHub issues indicating the objection.
>> >>> >> >
>> >>> >> > * The idea of synonyms or aliases was raised (disclosure: by me),
>> >>> >> > discussed
>> >>> >> > but not adopted, i.e. TTML namespace syntax for features where
>> >>> >> > each
>> >>> >> > feature
>> >>> >> > is a functional equivalent or superset of an IMSC 1.0.1
>> >>> >> > extension,
>> >>> >> > and
>> >>> >> > both
>> >>> >> > may be supported in IMSC 1.1 with a mapping to the canonical
>> >>> >> > TTML2
>> >>> >> > equivalent. The synonym may additionally be noted informatively
>> >>> >> > in
>> >>> >> > TTML2.
>> >>> >> > The key negative point was that it would encourage the use of
>> >>> >> > both
>> >>> >> > sets
>> >>> >> > of
>> >>> >> > syntax in many documents with no clear end point to the practice
>> >>> >> > and
>> >>> >> > no
>> >>> >> > practical benefit. However I cannot recall any formal objection,
>> >>> >> > nor
>> >>> >> > find
>> >>> >> > one in the minutes.
>> >>> >> >
>> >>> >> > The Netflix objection essentially requests that this latter model
>> >>> >> > be
>> >>> >> > adopted, whilst deprecating the IMSC 1.0.1 extensions.
>> >>> >> >
>> >>> >> > Given that I cannot recall any formal objection to the
>> >>> >> > synonym/alias
>> >>> >> > proposal requested by Netflix, I'd like to check if we actually
>> >>> >> > have
>> >>> >> > consensus to adopt it already, i.e. if despite it not being
>> >>> >> > everyone's
>> >>> >> > favourite option, it is something that everyone can nevertheless
>> >>> >> > live
>> >>> >> > with.
>> >>> >> >
>> >>> >> > Does anyone object to any of the Netflix proposals? If so, please
>> >>> >> > be
>> >>> >> > specific about the nature of the objection. This will help us to
>> >>> >> > construct
>> >>> >> > new proposals.
>> >>> >> >
>> >>> >> > This topic will be on the agenda for next week's call (November
>> >>> >> > 30th),
>> >>> >> > but
>> >>> >> > if possible I would like to have a sense of the conclusion or any
>> >>> >> > as
>> >>> >> > yet
>> >>> >> > unraised concerns before the meeting. If anyone would like a call
>> >>> >> > with
>> >>> >> > me or
>> >>> >> > others to discuss this informally ahead of the meeting, I am
>> >>> >> > happy
>> >>> >> > to
>> >>> >> > support that, and can be available on Monday 1600-1700 UK time,
>> >>> >> > Tuesday
>> >>> >> > 1630-1730 UK time or Wednesday 1500-1730 UK time.
>> >>> >> >
>> >>> >> > Nigel
>> >>> >> >
>> >>> >> >
>> >>> >> > From: Cyril Concolato <cconcolato@netflix.com>
>> >>> >> > Date: Wednesday, 15 November 2017 at 18:55
>> >>> >> > To: TTWG <public-tt@w3.org>
>> >>> >> > Subject: Objections to TPAC resolutions on IMSC1.1
>> >>> >> > Resent-From: <public-tt@w3.org>
>> >>> >> > Resent-Date: Wednesday, 15 November 2017 at 18:56
>> >>> >> >
>> >>> >> > Dear TTWG experts,
>> >>> >> >
>> >>> >> >
>> >>> >> > Following TPAC, Netflix would like to inform the group that it is
>> >>> >> > not
>> >>> >> > satisfied with some of the resolutions regarding IMSC1.1 and
>> >>> >> > objects
>> >>> >> > to
>> >>> >> > them. Netflix thinks that two important goals must be satisfied
>> >>> >> > in
>> >>> >> > defining
>> >>> >> > TTML2 and IMSC1.1:
>> >>> >> >
>> >>> >> > - IMSC1.1 must be a strict-subset of TTML2, aside from deprecated
>> >>> >> > features.
>> >>> >> > We believe it is bad practice for W3C to define two TTML-based
>> >>> >> > standards, at
>> >>> >> > the same time, which are not compatible with each other.
>> >>> >> >
>> >>> >> > - TTML2 must limit its normative references to Web Platform
>> >>> >> > standards.
>> >>> >> > We
>> >>> >> > believe it is bad practice to have to compile multiple sources of
>> >>> >> > information outside of the Web Platform to implement the
>> >>> >> > standard.
>> >>> >> >
>> >>> >> >
>> >>> >> > Netflix asks for the following actions:
>> >>> >> >
>> >>> >> > a) Marking ittp:activeArea deprecated in IMSC1.1, using a
>> >>> >> > reference
>> >>> >> > to
>> >>> >> > IMSC1.0.1 and no definition in IMSC1.1, in favor of
>> >>> >> > ttp:activeArea,
>> >>> >> > restricted to using two-component values such that ttp:activeArea
>> >>> >> > can be
>> >>> >> > used to do no more than IMSC1.0.1 ittp:activeArea.
>> >>> >> >
>> >>> >> > b) Marking ittp:aspectRatio deprecated in IMSC1.1, using a
>> >>> >> > reference
>> >>> >> > to
>> >>> >> > IMSC1.0.1 and no definition in IMSC1.1, in favor of
>> >>> >> > ttp:displayAspectRatio.
>> >>> >> > There does not seem to be a need for restricting
>> >>> >> > ttp:displayAspectRatio.
>> >>> >> >
>> >>> >> > c) Marking itts:forcedDisplay deprecated in IMSC1.1, using a
>> >>> >> > reference
>> >>> >> > to
>> >>> >> > IMSC1.0.1 and no definition in IMSC1.1, in favor of a combination
>> >>> >> > of
>> >>> >> > 'condition' and 'tts:visibility', with the appropriate
>> >>> >> > restrictions
>> >>> >> > on
>> >>> >> > condition such that it remains simple to implement, while at the
>> >>> >> > same
>> >>> >> > time
>> >>> >> > offering more flexibility than forcedDisplay.
>> >>> >> >
>> >>> >> > d) Adding the definitions of itts:fillLineGap, ebutts:linePadding
>> >>> >> > and
>> >>> >> > ebutts:multiRowAlign to TTML2, with no change to the semantics,
>> >>> >> > but
>> >>> >> > in
>> >>> >> > the
>> >>> >> > TTML namespace; and marking the itts/ebutts version as deprecated
>> >>> >> > in
>> >>> >> > IMSC1.1.
>> >>> >> >
>> >>> >> > e) IMSC1.1 should indicate that when TTML2 features are used in
>> >>> >> > the
>> >>> >> > same
>> >>> >> > document at the same time as their non-TTML2 equivalent and
>> >>> >> > deprecated
>> >>> >> > features, the TTML2 features prevail. This insures that future
>> >>> >> > versions
>> >>> >> > of
>> >>> >> > IMSC can effectively remove the features marked as deprecated.
>> >>> >> >
>> >>> >> >
>> >>> >> > Netflix believes that this approach provides clearly designed,
>> >>> >> > forward
>> >>> >> > looking standards, reducing the complexity of the TTML ecosystem.
>> >>> >> >
>> >>> >> >
>> >>> >> > Netflix is aware that this requires an effort of the TTML
>> >>> >> > community
>> >>> >> > as
>> >>> >> > follows:
>> >>> >> >
>> >>> >> > - IMSC1.0.1 renderers do not need to be updated, unless they need
>> >>> >> > to
>> >>> >> > support
>> >>> >> > Japanese features. The changes required by the proposed dual
>> >>> >> > syntax
>> >>> >> > and
>> >>> >> > deprecation model are minor compared to them, as they can be
>> >>> >> > implemented
>> >>> >> > using aliases or simple transforms.
>> >>> >> >
>> >>> >> > - Authoring tools already supporting IMSC1.0.1 do not need to
>> >>> >> > migrate to
>> >>> >> > the
>> >>> >> > TTML2 syntax, as renderers are required to support both. They
>> >>> >> > only
>> >>> >> > need
>> >>> >> > to
>> >>> >> > be updated to support Japanese features. They would need to be
>> >>> >> > updated
>> >>> >> > when
>> >>> >> > the deprecated features are removed in a future version.
>> >>> >> >
>> >>> >> > - Specs need to be updated. Netflix is willing to update the
>> >>> >> > TTML2
>> >>> >> > and
>> >>> >> > IMSC1.1 specs as proposed above.
>> >>> >> >
>> >>> >> > - Test suites need to be updated. For each of the features above,
>> >>> >> > 2
>> >>> >> > additional tests need to be provided: one with the TTML2 flavor
>> >>> >> > and
>> >>> >> > without
>> >>> >> > the IMSC1.0.1 flavor; and one with both (testing the override
>> >>> >> > model).
>> >>> >> > Netflix is willing to contribute these tests.
>> >>> >> >
>> >>> >> >
>> >>> >> > We suggest adding these points to the next meeting's agenda.
>> >>> >> >
>> >>> >> >
>> >>> >> > Best regards,
>> >>> >> >
>> >>> >> > Cyril
>> >>> >> >
>> >>> >> >
>> >>> >>
>> >>> >
>> >>
>> >>
>> >
>
>

Received on Tuesday, 28 November 2017 05:18:47 UTC