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RE: ISSUE-98 (Clear timing.): Eliminate separate clear timing from dynamicFlow [DFXP 1.0]

From: Sean Hayes <Sean.Hayes@microsoft.com>
Date: Fri, 15 May 2009 14:13:16 +0100
To: Geoff Freed <geoff_freed@wgbh.org>, Timed Text Working Group WG <public-tt@w3.org>
Message-ID: <AB3FC8E280628440B366A29DABB6B6E8075D4F53A2@EA-EXMSG-C334.europe.corp.microsoft.com>
Actually I think you are agreeing with me :-)

The 'move up' you are talking about is the internal reflow and line wrap which happens when I add content to the region as part of the fill (assuming displayAlign is after)

Clear is about removing content from any consideration as part of the region, which I agree should be determined by overflow caused by the fill rate and not by the author. The size of the clear unit can be independently specified, but its rate should not be, because its timing should be dependent on overflow caused by the fill.

Sean Hayes
Media Accessibility Strategist
Accessibility Business Unit
Microsoft

Office:  +44 118 909 5867,
Mobile: +44 7875 091385


-----Original Message-----
From: public-tt-request@w3.org [mailto:public-tt-request@w3.org] On Behalf Of Geoff Freed
Sent: 15 May 2009 2:04 PM
To: Timed Text Working Group WG
Subject: RE: ISSUE-98 (Clear timing.): Eliminate separate clear timing from dynamicFlow [DFXP 1.0]


I'm not sure I agree, but it may be because I'm misunderstanding something about this requirement.

According to 8.3.7 flowIntervalFunctio (http://www.w3.org/TR/2009/WD-ttaf1-dfxp-20090511/), B.5.1 Fill Timer (http://www.w3.org/TR/2009/WD-ttaf1-dfxp-20090511/#flowTimerFill) and B.5.2 Clear Timer (http://www.w3.org/TR/2009/WD-ttaf1-dfxp-20090511/#flowTimerClear), I ought to be able to fill up a row of text and, when it is ready to overflow, the row will move up and make space for the next row, and so on.  All this is done without my having to *specify* the time at which the clear occurs.  The clear function is automatic.  Do I have this right?  If so, then I'd rather keep clear timing because I don't want to have to specify a clear on every row of text-- I want to be able to send a row of text to a rollup region,  have it clear automatically when the row is full and then start filling the next row.

g.


________________________________________
From: public-tt-request@w3.org [public-tt-request@w3.org] On Behalf Of Timed Text Working Group Issue Tracker [sysbot+tracker@w3.org]
Sent: Friday, May 15, 2009 6:49 AM
To: public-tt@w3.org
Subject: ISSUE-98 (Clear timing.): Eliminate separate clear timing from dynamicFlow [DFXP 1.0]

ISSUE-98 (Clear timing.): Eliminate separate clear timing from dynamicFlow [DFXP 1.0]

http://www.w3.org/AudioVideo/TT/tracker/issues/98

Raised by: Sean Hayes
On product: DFXP 1.0

I can see no justification for having separate clear timing in any of the examples from John Birch's original documents (the only hard evidence I can find in the history trail of a design discussion). The notion of a separate clear timer seems to have been added between the March 14 draft and March 21 draft without discussion on the public list. What is more, the presence of a separate clear interval seems at somewhat at odds with the behavioral requirement.

If I have a two line caption region , and I wish to flow the text through it, with text entering at a word rate and leaving at a line rate. Then I don't want a clear to occur until after two lines have been added, but then I want to clear the lines after each additional line is completed; which implies clear timing can't start until the region starts to overflow, so the first clear interval needs to be extended, and after that we want the clear interval to be synchronized with the fill interval which is based on irregular length words, so a single value seems inappropriate.

In the example flow below: The first clear/reflow occurs at t14, the next at t20, then at t27 and at t33  (clear intervals of 14, 6, 7 6), then we presumably want to clear the remaining two lines to be cleared in some manner.

T01 Alice

t02 Alice was

....

t06 Alice was beginning to get very

t07 Alice was beginning to get very
       tired

....

t13 Alice was beginning to get very
       tired of sitting by her sister on

t14 tired of sitting by her sister on
       the
...
T19 tired of sitting by her sister on
        the bank and of having nothing

T20 the bank and of having nothing
        to
....

T26 the bank and of having nothing
        to do: once or twice she had

T27 to do: once or twice she had
        peeped

T33 peeped into the book her sister
        was

T34 peeped into the book her sister
        was reading
Received on Friday, 15 May 2009 13:14:11 GMT

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