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Re: proposed updated response to MPEG on codecs

From: Andreas Tai <tai@irt.de>
Date: Sat, 18 Oct 2014 16:54:04 +0200
Message-ID: <54427F0C.8070504@irt.de>
To: Glenn Adams <glenn@skynav.com>
CC: Cyril Concolato <cyril.concolato@telecom-paristech.fr>, TTWG <public-tt@w3.org>
Am 18.10.2014 um 16:37 schrieb Glenn Adams:
>
> On Sat, Oct 18, 2014 at 4:56 AM, Andreas Tai <tai@irt.de 
> <mailto:tai@irt.de>> wrote:
>
>     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?
>
>
> Correct, it would not be a "TTML profile" in the formal sense of how 
> TTML uses the term profile. However, in a general sense it might be 
> considered an "informal profile of TTML". In any case, it would 
> certainly confuse users and authors, and to some extent, would subvert 
> the intended use of TTML.
>
>
Thanks, Glenn! I think it is important that the proposed mechanism can 
be used by a wide range of subtitle format specifications that are based 
on TTML and have a potential use case to be transmitted in MP4. The 
mechanism should not be exclusive to specifications that make explicit 
use of TTML profiles. A solution for the discussed scenario should make 
this very clear.

Best regards,

Andreas

>     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  <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 14:55:43 UTC

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