Re: ISSUE-406 + #lineBreak-uax14

HI Glenn,

> I presumed that by listing feature designators, you were specifying whether the features so designated may be used in a document.

Yes. This is the intent.

> it appears you may in addition consider the presence of a designator in these sections as indicating whether
> a feature can be required in a document specific profile over and above the use of an IMSC profile.

No. That is not the intent.

I was merely curious why, as opposed to other TTML parameter that
impact processor behavior, #lineBreak-uax14 is not controlled using a
ttp attribute.

> Given the focus on reproducible behavior, e.g., defining the use of specific glyph metrics, I would expect that UAX14 be mandated by IMSC1.

Ok. To confirm, unless IMSC1 requires that processor implement
#lineBreak-uax14, a processor may or may not do so.

Best,

-- Pierre

On Mon, Sep 21, 2015 at 2:15 PM, Glenn Adams <glenn@skynav.com> wrote:
> I was not sufficiently clear in my description. Of course, the
> #lineBreak-uax14 designator can be listed in a document defined profile
> based on IMSC1 text profile as the base profile.
>
> What I had apparently not understood was what was meant by "The Document
> Instance shall conform to the following table:" in Sections 6.10, 7.4,  and
> 8.4. I presumed that by listing feature designators, you were specifying
> whether the features so designated may be used in a document. In the case of
> most features, there is a syntactic feature that corresponds to a
> designator. However, that is not true for #lineBreak-uax14, which may be
> used by an application to signal whether a particular algorithm is used or
> not by the implementation, as opposed to whether a syntactic feature is used
> in the document.
>
> From your question, it appears you may in addition consider the presence of
> a designator in these sections as indicating whether a feature can be
> required in a document specific profile over and above the use of an IMSC
> profile.
>
> This doesn't seem a legitimate requirement. If an application of IMSC1 also
> wants to require an implementation to support a superset of IMSC1, then they
> should be able to additional require features not required by IMSC1.
>
> Furthermore, I wonder if the fact that absent a generic requirement for
> UAX14 line break support, then there is no guarantee of reproducibility of
> line breaks even given the same font metrics, same resolution, and same
> region extents?
>
> Given the focus on reproducible behavior, e.g., defining the use of specific
> glyph metrics, I would expect that UAX14 be mandated by IMSC1.
>
>
>
>
>
>
>
> On Mon, Sep 21, 2015 at 9:35 AM, Pierre-Anthony Lemieux <pal@sandflow.com>
> wrote:
>>
>> Hi Glenn,
>>
>> Couple of questions related to #lineBreak-uax14 and ISSUE-406 [1].
>>
>> - why can #lineBreak-uax14 only be signaled through a profile
>> declaration and cannot be set through a ttp attribute?
>>
>> - what is the default value of #lineBreak-uax14 in absence of a
>> profile declaration?
>>
>> Thanks,
>>
>> -- Pierre
>>
>> [1] http://www.w3.org/AudioVideo/TT/tracker/issues/406
>>
>

Received on Monday, 21 September 2015 21:44:18 UTC