Re: ISSUE-446: Should be a subset of IMSC1 [TTML WebVTT mapping note]

Hi David and Nigel,

For one thing, as mentioned in the ticket, selecting an existing
profile of TTML as a starting point simplifies the mapping task, e.g.
no need to consider #markerMode or #pixekAspectRatio. In addition, in
the case of IMSC1, it also allows (limited) support of CSS features
like background-image, not available in vanilla TTML1.

Best,

-- Pierre

On Wed, Sep 23, 2015 at 3:49 PM, David Singer <singer@apple.com> wrote:
>
>> On Sep 23, 2015, at 4:10 , Nigel Megitt <nigel.megitt@bbc.co.uk> wrote:
>>
>> I disagree that the T2VP profile should be deliberately constrained to be
>> a subset of IMSC1, because it would be too limiting and wasn't specified
>> in the charter description of this Note.
>
> I’m with Nigel.  Well, mostly. No, no, I support him.
>
> Let’s work out the best mapping, and then if the mapped part of TTML is not cleanly part of a current profile, think about how to handle that case. So I am sort of with both of you: I don’t want to constrain the mapping work a priori, but I also don’t want to emerge with a needless mismatch a posteriori.
>
>>
>> I do agree that if there are significant things that prevent IMSC 1 from
>> being mappable to WebVTT then we should look at the discrepancies and try
>> to reconcile them. I also would not object to an additional set of
>> constraints that explain what limitations would apply to WebVTT in order
>> to convert it to IMSC 1, extra to what could be done if mapping to TTML1
>> more generally.
>>
>> Some obvious things that aren't in WebVTT but are constraints of IMSC 1
>> that I do not think we need to carry over are the reference fonts, the
>> simultaneously active region limit and the HRM.
>
> Yup.
>
>>
>> Nigel
>>
>>
>> On 23/09/2015 05:51, "Timed Text Working Group Issue Tracker"
>> <sysbot+tracker@w3.org> wrote:
>>
>>> ISSUE-446: Should be a subset of IMSC1 [TTML WebVTT mapping note]
>>>
>>> http://www.w3.org/AudioVideo/TT/tracker/issues/446
>>>
>>> Raised by: Pierre-Anthony Lemieux
>>> On product: TTML WebVTT mapping note
>>>
>>> The profile/authoring guidelines specified in the document should be a
>>> subset of IMSC1:
>>>
>>> - it helps narrow down the set of features to be supported, e.g. no need
>>> to support #markerMode
>>> - it simplifies the job of implementers who are already supporting IMSC1
>>>
>>> Features have been deemed necessary but are not in IMSC1 should be
>>> considered for addition there.
>>>
>>>
>>>
>>
>>
>>
>> -----------------------------
>> http://www.bbc.co.uk
>> This e-mail (and any attachments) is confidential and
>> may contain personal views which are not the views of the BBC unless specifically stated.
>> If you have received it in
>> error, please delete it from your system.
>> Do not use, copy or disclose the
>> information in any way nor act in reliance on it and notify the sender
>> immediately.
>> Please note that the BBC monitors e-mails
>> sent or received.
>> Further communication will signify your consent to
>> this.
>> -----------------------------
>
> David Singer
> Manager, Software Standards, Apple Inc.
>
>

Received on Wednesday, 23 September 2015 22:56:15 UTC