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Re: IMSC1 WD wide review and CR draft.

From: Andreas Tai <tai@irt.de>
Date: Mon, 27 Oct 2014 12:07:54 +0100
Message-ID: <544E278A.9030901@irt.de>
To: Thierry MICHEL <tmichel@w3.org>
CC: Nigel Megitt <nigel.megitt@bbc.co.uk>, Pierre-Anthony Lemieux <pal@sandflow.com>, W3C Public TTWG <public-tt@w3.org>
Hi Thierry,

First congratulation to the very good spec document!

Apart from a few issues most of my observations are not critical. They 
can be seen more as a proposal for the editor. I am sending the comments 
on my behalf.

The more important issues first:

----------------------------------
5.2 Foreign Elements and Attributes
-----------------------------------
It would be good to give more emphasis that a presentation processor 
should not reject a document "with foreign namespace elements or 
attributes".

Examples for possible edits:
a) "...*The subtitle document SHALL be processed but* such elements and 
attributes may be ignored by the presentation processor or 
transformation processor."

b) "A *conforming* subtitle document may contain elements and attributes 
that are neither specifically permitted nor forbidden by a profile."

It may be a good idea to align this paragraph with the section in TTML 
5.3.2. As far as I can see it is not explicitly forbidden to use the 
IMSC namespaces for extensions. So either in IMSC 1 5.3 or somewhere 
else an additional constraint may be added.

-----------------------------------
5.10 Features (Common features) #length-cell feature
-----------------------------------
IMSC 1 states that the #length-cell feature shall not be used. The 
line-padding extension uses the cell metric. Not sure if this causes a 
problem. On the one hand the extensions are "outside" of TTML 1 on the 
other hand they use the cell metric as defined by TTML 1.

-----------------------------------
5.10 Features (Common features) -#length feature
-----------------------------------
The #length feature includes the support of the "c" metric 
(http://www.w3.org/TR/ttml1/#feature-length). So you may add a 
restriction here.

Some other observations in document order:
------------------------------
3. Conformance
------------------------------
The term "subtitle document" is not defined in IMSC 1 and TTML 1 but 
used frequently in a normative context. It may be helpful to define it 
in Section 2.

------------------------------
4.1 General
------------------------------
 From IMSC 1:
"In addition, the Text Profile subtitle document SHOULD be associated 
with the Image Profile subtitle document such that, when image content 
is encountered, assistive technologies have access to its corresponding 
text form."

As far as I could see there is no defined method to link a Text profile 
document to an Image Profile document through an element in the document 
themselves. So it may helpful to add that his has to be done through an 
external setting.

------------------------------
5.7.3 itts:forcedDisplay - value matrix
------------------------------
In general I would welcome a bit more text about the details of value 
combinations. There is text for "displayForcedMode=true, 
itts:forcedDisplay=false" but not for "displayForcedMode=true, 
itts:forcedDisplay=true". Maybe a matrix would be helpful with 
tts:visibilily (visible, hidden), displayForcedDisplay parameter (true, 
fase) annd itts:forcedDisplay (true, false).

------------------------------
5.7.3 itts:forcedDisplay - Informative Note
------------------------------
The first note could possibly be improved if it is noted that this has 
an effect only if a "non-transparent background" is directly defined for 
the region (e.g. in most cases I have seen for the usage of EBU-TT-D the 
background will be applied through the content elements).


------------------------------
5.7.4 ittm:altText - Optionality of attributes
------------------------------
For the XML Representation you may repeat the part from 2.3 TTML 1 where 
it states that bold-face attribute names are required and the others are 
optional (personally I would prefer the keyword "REQUIRED" after the 
attribute name). Without that it may not be clear if the attributes are 
optional or required.


------------------------------
5.7.4 ittm:altText - Typo
------------------------------
End of "Note:": Replace ". ." with "."

------------------------------
5.10 Features (Common)
------------------------------
#timing: It may be helpful to describe what you mean with the same 
syntax (e.g. is 00:00:01, 00:00:01.0 and 00:00:01.000 a different syntax?)

------------------------------
6.3 Features (Text Profile)
------------------------------
#textAlgin: A reference to the definition of the "defaultRegion" in TTML 
1 would be helpful. I assume that ony the TTML experts know what the 
defaultRegion is (e.g. some implementers gave in a TTML document 
"defaultRegion" as value for xml:id).

-----------------------------
8.2 Reference Fonts
-----------------------------
A reference to presentation processors and transformation processors may 
be helpful. A presentation processor SHALL lay out the text according to 
the metrics and a transformation processor should use this metrics for 
any calculation.

------------------------
Annex B Forced Content
------------------------
A code example may be an illustrative help for the shown use case.

Best regards,

Andreas

-- 
------------------------------------------------
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
------------------------------------------------



Am 03.10.2014 um 16:32 schrieb Thierry MICHEL:
> Pierre, Nigel, TTWG,
>
> Now that we have published the IMSC1 WD for wide review, we should be 
> tracking incoming comments on public-tt@w3.org.
>
> If there are comments coming in, we should discuss those, by email or 
> during calls, or at F2F and come to a WG resolution. Then the WD 
> should respond to each commenter to collect his approval.
> (We don't necessary have to accept the proposal from the commenter, 
> but if we don't, we should explain  why it is only partially 
> adopted/postponed or rejected/, etc.
> Finally, if the commenter does not agree to our resolution, we will 
> make our case to the Director.
>
> In parallel we should start working on the CR draft.
>
> Therefore I have drafted the SOTD section [1]  for this CR, that 
> Pierre may incorporate in his document.
>
> Please look at the exit criteria and the end date of CR (set for 31 
> dec 2014), and let's discuss those.
>
> Thierry.
>
>
> [1] https://www.w3.org/2014/09/WD-ttml-imsc1-20141014/
>
>
>


-- 
------------------------------------------------
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 Monday, 27 October 2014 11:08:42 UTC

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