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Re: proposed updated response to MPEG on codecs

From: Cyril Concolato <cyril.concolato@telecom-paristech.fr>
Date: Fri, 17 Oct 2014 15:32:11 +0200
Message-ID: <54411A5B.4040902@telecom-paristech.fr>
To: public-tt@w3.org
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. 
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? Maybe the terms 
profiles or processorProfiles are misleading, I don't know. Maybe we 
should talk about dialects to cover not just profiles of TTML but 
extensions too.

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]
>> 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]
>> 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> 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> wrote:
>>> On Oct 16, 2014, at 10:22 , Michael Dolan <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]
>>>> 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> 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]
>>>> 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>
>>>> Date: Thursday, 16 October 2014 16:29
>>>> To: 'Timed Text Working Group' <public-tt@w3.org>
>>>> Subject: proposed updated response to MPEG on codecs
>>>> Resent-From: <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
>>>> mdolan@newtbt.com
>>> David Singer
>>> Manager, Software Standards, Apple Inc.
>>>
>>>
>>>
>> David Singer
>> Manager, Software Standards, Apple Inc.
>>
>>
>
>


-- 
Cyril Concolato
Multimedia Group / Telecom ParisTech
http://concolato.wp.mines-telecom.fr/
@cconcolato
Received on Friday, 17 October 2014 13:32:38 UTC

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