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RE: Timed Text Authoring Format - Distribution Format Exchange Pr ofile (DFXP)

From: Glenn A. Adams <gadams@xfsi.com>
Date: Thu, 17 Mar 2005 08:53:27 -0500
Message-ID: <7249D02C4D2DFD4D80F2E040E8CAF37C06C6B4@longxuyen.xfsi.com>
To: <Johnb@screen.subtitling.com>
Cc: <public-tt@w3.org>



From: Johnb@screen.subtitling.com [mailto:Johnb@screen.subtitling.com] 
Sent: Thursday, March 17, 2005 6:37 AM
To: Glenn A. Adams
Cc: public-tt@w3.org
Subject: RE: Timed Text Authoring Format - Distribution Format Exchange
Pr ofile (DFXP)




Thanks for the speedy reply - some more comments inline :-)


best regards


John Birch

	-----Original Message-----
	From: Glenn A. Adams [mailto:gadams@xfsi.com]
	Sent: 16 March 2005 17:55
	To: Johnb@screen.subtitling.com
	Cc: public-tt@w3.org
	Subject: RE: Timed Text Authoring Format - Distribution Format
Exchange Pr ofile (DFXP)


	7.1.1 tt

	If begin and (or) end attributes are specified on the tt
element, then they specify the beginning and (or) ending points of a
time interval for a document instance in relationship with some external
application or presentation context. The temporal begin and end points
determined by an external application or presentation are referred to
subsequently as the external time interval.

	Is it necessary to have begin and (or) end attributes for both
the tt element and the body element? Could this be simplified so that
begin and (or) end is only specified on the tt element?


	No. Neither is required. Is there something in the text that led
you to infer that both were required? 


	Ahhh.... I didn't make myself clear.... What I meant to say
was.... does the DXFP  specification need to support a begin / end
attribute on both the tt element and the body element? Would it be
possible to simplify the DXFP **specification** by removing timing
attributes from one of these elements, since I cannot see any situation
that requires both elements to have timing attributes. IMHO a document
using timing attributes on both tt and body can be **equivalently**
represented by a single set of timing attributes on just one of these
elements. Am I missing something? What is gained by having timing
attributes at both levels in the document hierarchy, given that both tt
and body can only occur once in a document instance?


	The timing attributes were added to <tt/> to support timing on
<set/> children of <region/> whose ancestors are <layout/>, <head/>,
then <tt/>.


	8.2.19 tts:textAlign


	Applies to:        p


	Can we allow tts:textAlign to apply to span as well. Otherwise,
I don't believe it is possible to have:




Come In!

Please have a seat



	No. You cannot do this in a single paragraph. You would have to
overlay two regions on top of one another and have one of them use a
transparent background.  


	A bit ugly - and prone to problems with text collisions which I
would hope to avoid! Imagine if the second phrase were modified to read
"Come In! I've been waiting to meet you."


	Text alignment (in the inline progression dimension) applies to
the positioning of line areas within a block area. A text alignment on a
span would always pertain individually to each inline area produced by
the span, and since each such inline area is bounded by glyph areas at
both start and end edges, there would be no extra room in which to move
those glyph areas within the inline area.


	Is there no way to createan inline block area that fills to the
end of the line (region)? I am assuming that the DXFP for the above
would be:


	<p id="subtitle5" begin="10:00:00:00" end="10:00:05:00"

	<span tts:textAlign="left">



	<span begin="10:00:02:00">

	Come In!</br>Please have a seat







	<p id="subtitle5" begin="10:00:00:00" end="10:00:05:00"

	<span tts:textAlign="left">




	<span begin="2:00">

	Come In!




	<p id="subtitle 6 " begin="10:00:02:00" end="10:00:05:00"

	Please have a seat




	So why can the first span not create an inline area that is left
aligned within the region and contains the text Hello?, terminating in
area just after the ? When the second span activates - can the inline
area generated not stretch from the previous inline area until the end
of the line - there is an explicit break in the first example and an
implicit break in the second?


	We base our basic formatting/layout semantics on XSL 1.0, which
does not support text-align on inline-level formatting objects. The
closest feature in XSL that would support this would be the use of
inline margins, e.g.,


	<fo:block text-align="end">


	<fo:inline space-start.minimum="0px" space-start.maximum="200px"
space-start.opt="200px">Come In!</fo:inline>

	<fo:character character="&#x000A;"/>

	<fo:inline space-start.minimum="0px" space-start.maximum="200px"
space-start.opt="200px">Please have a seat</fo:inline>



	Supporting this in DFXP would require introducing an equivalent
of the space-* properties of XSL, which involves a level of complexity
that may not be appropriate for this profile (and will certainly require
discussion by the WG).


	If I were using TeX, I would handle by inserting an \hskip or
\hfil command possibly with a \penalty command before or after to adjust
line break precedence rules.


	Another, but more complex means for handling this would be to
introduce a construct or mechanism that works similar to TAB in
traditional word processors.  


	Ugghhhh! Really really Ugghhhh! 

	I am not sure how you could use a tab construct, you would need
to position the tab by knowing how long the rendered second phrase (the
right aligned part) was - since the right aligned part would actually be
left aligned to the tab. 


	Another way to handle, but using a simpler, yet manual approach,
would be to use multiple non-breaking spaces before "Come" and "Please".



	Thisapproach would not work for regions that were specified with
relative (proportionate) sizes and would not achieve the same results
for different font sizes (or indeed fonts). Admittedly, this is how the
above effect is currently achieved though!


	I suspect this is what you will end up doing in DFXP as well.







	From: Johnb@screen.subtitling.com
	Sent: Wednesday, March 16, 2005 10:48 AM
	To: public-tt@w3.org
	Subject: RE: Timed Text Authoring Format - Distribution Format
Exchange Pr ofile (DFXP)


	Glenn, et al, 

	I have a number of minor comments / questions regarding the
draft that I have placed in the attached Word document. Apologies for
using this format but it allows me to easily illustrate certain points
regarding formatting without generating images.

	I have a couple of other points that I will make in separate

	with best regards 
	John Birch. 


	-----Original Message----- 
	From: Glenn A. Adams [mailto:gadams@xfsi.com] 
	Sent: 14 March 2005 16:51 
	To: public-tt@w3.org 
	Subject: Timed Text Authoring Format - Distribution Format
	Profile (DFXP) 


	A new update of the Timed Text Authoring Format 1.0 -
	Format Exchange Profile (DFXP), is now available at [1]: 


	The TT WG solicits your comments on this new draft as soon as
	as a very rapid turn-around is expected in order to publish a
first Last 
	Call (LC) draft. 

	Please sent comments either to this list or, if you prefer
privacy, to 
	me directly. 

	Glenn Adams 


Received on Thursday, 17 March 2005 13:53:25 UTC

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