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Re: proposed updated response to MPEG on codecs

From: Andreas Tai <tai@irt.de>
Date: Sat, 18 Oct 2014 12:56:51 +0200
Message-ID: <54424773.9080504@irt.de>
To: Glenn Adams <glenn@skynav.com>
CC: Cyril Concolato <cyril.concolato@telecom-paristech.fr>, TTWG <public-tt@w3.org>
Understood. One question: A specification that builds on TTML and but 
has not a normative list of TTML features and extensions is not a TTML 
profile, correct?

Best regards,

Andreas

Am 17.10.2014 um 18:53 schrieb Glenn Adams:
> I'm afraid I will have to object to the notion of creating a thing 
> called a TTML "dialect" that is not describable as a TTML "profile". 
> We definitely *do not* need an alternative characterization of TTML 
> processor requirements or content constraints.
>
> On Fri, Oct 17, 2014 at 8:23 AM, Andreas Tai <tai@irt.de 
> <mailto:tai@irt.de>> wrote:
>
>     Hi Cyril,
>
>     Thanks for the quick feedback! See some comment inline.
>
>     Am 17.10.2014 um 15:32 schrieb Cyril Concolato:
>
>         Hi Andreas,
>
>         Le 17/10/2014 14:33, Andreas Tai a écrit :
>
>             As I understand the main intent of this communication is
>             to define the responsibilities of the MPEG and TTWG  for
>             the signalling of "TTML document dialects" in an MP4
>             container. There seems an agreement to use the MPEG codecs
>             parameter where MPEG has the task to define a prefix and
>             TTWG to define suffix.
>
>             How the W3C/TTWG defines that suffix is not of core
>             interest for the MPEG group (as long the general syntax
>             for codecs parameter is followed). I highlight this
>             because my following comment may not stop this letter
>             because the "Suffix" definition is not decided yet and in
>             the responsibility of the TTWG.
>
>             Regarding the proposed solution in the liaison letter (and
>             in this thread) more discussion seems to be needed. From
>             my current review it may not be applicable for all "TTML
>             dialects". Some "dialects", like EBU-TT-D, do not rely on
>             the defined semantics of TTML profiles. Therefore I do not
>             think that it is a good idea to make "TTML profiles" as a
>             central concept for the codecs registry for "TTML dialects".
>
>         The idea would be that EBU-TT-D would be registered and have a
>         short name to be used as a dialect in the processorProfiles
>         parameter.
>
>     In general this would meet an important requirement from decoder
>     implementers.
>
>         EBU-TT-D may not "rely on the defined semantics of TTML
>         profiles" but it can be viewed as a "dialect" of TTML. Is that
>         clearer?
>
>
>     I think that the general pattern is a adequate solution. The
>     problem I see is with the definition what is meant by a processor
>     profile. A processor profile has defined semantics. It reference
>     the TTML profile mechanism. This mechanism is a formally
>     well-thought-out concept. But it is not used consistently or not
>     used by some TTML dialects. As well it has not been fully
>     understood by some implementers. Therefore it would be good to
>     have the (additional) possibility to just reference the
>     specification of the "TTML dialect" without using the profile
>     semantics.
>
>         Maybe the terms profiles or processorProfiles are misleading,
>         I don't know.
>
>     In the current registry proposal (and in the TTML2) draft
>     "processor profile" has defined semantics. I think it was chosen
>     on purpose (although I do not agree that this is the best solution).
>
>     | Maybe we should talk about dialects to cover not just profiles
>     of TTML but extensions too.
>
>     I think the use of an alternative term would be a good idea
>     because "profile" has a link to the semantic concept of TTML
>     profiles and often this linkage is not intended.
>
>     Best regards,
>
>     Andreas
>
>
>
>         Cyril
>
>
>             Best regards,
>
>             Andreas
>
>             Am 17.10.2014 um 00:16 schrieb Michael Dolan:
>
>                 Take 2 on the communication to MPEG - attached. Over
>                 to Dave (really this
>                 time).
>
>                 -----Original Message-----
>                 From: Michael Dolan [mailto:mdolan@newtbt.com
>                 <mailto:mdolan@newtbt.com>]
>                 Sent: Thursday, October 16, 2014 1:35 PM
>                 To: 'Timed Text Working Group'
>                 Subject: RE: proposed updated response to MPEG on codecs
>
>                 That would be the proper thing to do.
>
>                 -----Original Message-----
>                 From: David Singer [mailto:singer@apple.com
>                 <mailto:singer@apple.com>]
>                 Sent: Thursday, October 16, 2014 1:07 PM
>                 To: Glenn Adams
>                 Cc: Michael Dolan; Timed Text Working Group
>                 Subject: Re: proposed updated response to MPEG on codecs
>
>                 Seems that way
>
>                 On Oct 16, 2014, at 12:57 , Glenn Adams
>                 <glenn@skynav.com <mailto:glenn@skynav.com>> wrote:
>
>                     we could always define this new MIME media type
>                     parameter in TTML2,
>                     but
>
>                 wouldn't we need to update the current registration?
>
>                     On Thu, Oct 16, 2014 at 1:01 PM, David (Standards)
>                     Singer
>
>                 <singer@apple.com <mailto:singer@apple.com>> wrote:
>
>                     On Oct 16, 2014, at 10:22 , Michael Dolan
>                     <mdolan@newtbt.com <mailto:mdolan@newtbt.com>> wrote:
>
>                         I cannot support defining a formal media type
>                         string (including any
>                         of
>
>                 its parameters) on an informal wiki.  This is highly
>                 irregular.
>
>                     agreed.  I think that MPEG should say "the mime
>                     type the contents
>                     would
>
>                 have if in a separate file goes here, with any
>                 optional parameters" and stop
>                 at that.
>
>                     So, MPEG doesn't care how irregular we are, but we
>                     should not be
>
>                 irregular, of course.
>
>                           I believe its general syntax and semantics
>                         must be normatively
>                         defined
>
>                 in TTML2 as part of the media type (and preferably in
>                 my view) then
>                 registered with IANA (not the other way around either).
>
>                     yup
>
>                                          Mike
>
>                         From: Nigel Megitt
>                         [mailto:nigel.megitt@bbc.co.uk
>                         <mailto:nigel.megitt@bbc.co.uk>]
>                         Sent: Thursday, October 16, 2014 9:23 AM
>                         To: Michael Dolan
>                         Cc: Timed Text Working Group
>                         Subject: Re: proposed updated response to MPEG
>                         on codecs
>
>
>
>
>                         On 16 Oct 2014, at 16:52, Michael Dolan
>                         <mdolan@newtbt.com <mailto:mdolan@newtbt.com>>
>                         wrote:
>
>                         Thanks for fixes.   I assume Dave will update
>                         before posting.
>
>                         As for the your second point, I am not sure
>                         that I follow. We must
>
>                 define the new media type parameter formally in TTML2
>                 or our decisions and
>                 this communication are meaningless.  Is your point
>                 that we did not agree as
>                 a group to register the update with IANA?  I agree,
>                 but I also did not say
>                 that to MPEG (although I personally think we should).
>
>
>                         I was expecting the MIME type parameter to be
>                         external to TTML2 and
>
>                 defined on the registry page. I'm not against updating
>                 the IANA registration
>                 if that's useful but we haven't decided to do that. If
>                 we do, then clearly
>                 the relevant part of the TTML 2 spec would need
>                 updating to match. If we
>                 don't, then there may be no changes resulting, in TTML2.
>
>                         Since there may therefore be no change in TTML
>                         2 I don't want to
>                         give
>
>                 the wrong impression.
>
>                         Nigel
>
>
>
>                                          Mike
>
>                         From: Nigel Megitt
>                         [mailto:nigel.megitt@bbc.co.uk
>                         <mailto:nigel.megitt@bbc.co.uk>]
>                         Sent: Thursday, October 16, 2014 8:39 AM
>                         To: Michael Dolan; 'Timed Text Working Group'
>                         Subject: Re: proposed updated response to MPEG
>                         on codecs
>
>                         Thanks for the quick turnaround Mike. 3 things:
>
>                         typo: s/medaType/mediaType
>                         correction: s/procProfile/processorProfiles
>
>                         Query: do we want the sentence "Its parameters
>                         will be extended in
>                         TTML2
>
>                 to include the proposed syntax above." ? Unless we're
>                 changing the IANA
>                 registration then I do not think we have agreed to do
>                 this.
>
>                         Kind regards,
>
>                         Nigel
>
>
>                         From: Michael Dolan <mdolan@newtbt.com
>                         <mailto:mdolan@newtbt.com>>
>                         Date: Thursday, 16 October 2014 16:29
>                         To: 'Timed Text Working Group'
>                         <public-tt@w3.org <mailto:public-tt@w3.org>>
>                         Subject: proposed updated response to MPEG on
>                         codecs
>                         Resent-From: <public-tt@w3.org
>                         <mailto:public-tt@w3.org>>
>                         Resent-Date: Thursday, 16 October 2014 16:30
>
>                         Per my action item from today, please see the
>                         attached.
>
>                         Over to Dave and Nigel for review to see if I
>                         captured where we
>                         ended up
>
>                 in today's call; then over to Dave to upload to MPEG
>                 (or I can if needed).
>
>                         Time is very short and should be posted Sunday
>                         morning CEDT.
>
>                         Regards,
>
>                                          Mike
>
>                         Michael A DOLAN
>                         TBT, Inc.  PO Box 190
>                         Del Mar, CA 92014
>                         (m) +1-858-882-7497 <tel:%2B1-858-882-7497>
>                         mdolan@newtbt.com <mailto:mdolan@newtbt.com>
>
>                     David Singer
>                     Manager, Software Standards, Apple Inc.
>
>
>
>                 David Singer
>                 Manager, Software Standards, Apple Inc.
>
>
>
>
>
>
>
>
>     -- 
>     ------------------------------------------------
>     Andreas Tai
>     Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH
>     R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR
>     Floriansmuehlstrasse 60, D-80939 Munich, Germany
>
>     Phone: +49 89 32399-389 <tel:%2B49%2089%2032399-389> | Fax: +49 89
>     32399-200 <tel:%2B49%2089%2032399-200>
>     http: www.irt.de <http://www.irt.de> | Email: tai@irt.de
>     <mailto:tai@irt.de>
>     ------------------------------------------------
>
>     registration court&  managing director:
>     Munich Commercial, RegNo. B 5191
>     Dr. Klaus Illgner-Fehns
>     ------------------------------------------------
>
>
>
>


-- 
------------------------------------------------
Andreas Tai
Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH
R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR
Floriansmuehlstrasse 60, D-80939 Munich, Germany

Phone: +49 89 32399-389 | Fax: +49 89 32399-200
http: www.irt.de | Email: tai@irt.de
------------------------------------------------

registration court&  managing director:
Munich Commercial, RegNo. B 5191
Dr. Klaus Illgner-Fehns
------------------------------------------------
Received on Saturday, 18 October 2014 10:58:51 UTC

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