RE: ISSUE-189: do regions scroll their flowed content? [DFXP 1.0]

Glenn-

 

We certainly both agree that there is no explicit language about automatic scrolling.  And, the end of line behavior is well documented, I think.

 

By way of example so we’re clear on the timed flow, the following TTML into a 2-line-height region:

 

<p begin=”1s” end=”3s”>first line</p>

<p begin=”2s” end=”4s”><br>second line</p>

<p begin=”3s”><br>third line</p>

 

Would result in the following text over the time periods shown:

 

1s-2s:

first line

<blank line>

 

2s-3s:

first line

second line

 

3s-4s:

second line

third line

 

4s on:

third line

<blank line>

 

Right? This would be a very instructive example, I think.

 

Regards,

 

                Mike

 

From: Glenn Adams [mailto:glenn@skynav.com] 
Sent: Thursday, September 27, 2012 5:48 PM
To: Michael A Dolan
Cc: Timed Text Working Group
Subject: Re: ISSUE-189: do regions scroll their flowed content? [DFXP 1.0]

 

Just to clarify, there is no "automatic region scrolling" defined in TTML for overfull conditions. For example:

 

(1) adding a new line to the end of a full region does not automatically remove the first line (unless that first line is also simultaneously taken out of temporal scope, i.e., timed to end its active duration at the same time the new line begins its active duration);

 

(2) adding a new character to the end of a full line of a full region does not automatically remove the first line for similar reasons;

 

Only if explicit timing is provided to remove content simultaneously with adding content can the note referred to below have an affect (provided the processor does what is recommended by the note).

 

The issue of whether this note is adequate, and if, not what normatively language is sufficient to specify this behavior at some acceptable degree of interoperability is another question.

 

On Fri, Sep 28, 2012 at 8:34 AM, Michael A Dolan <mdolan@newtbt.com> wrote:

The note was carefully crafted not to presume there was any actual region scrolling in the presentation processor. However, if we confirm there is no defined scrolling, then (in addition to explicitly saying that) the new text below probably needs to clarify that “similarity” is not the result of an automatic region scroll, but two synchronic documents resulting from some other event.

 

At this point, I don’t much care which way it is.  But we can’t leave region scrolling to be presentation processor dependent, which is the state we seem to be in now. That’s just non-interoperable.

 

Regards,

 

                Mike

 

From: Glenn Adams [mailto:glenn@skynav.com] 
Sent: Thursday, September 27, 2012 5:06 PM
To: Timed Text Working Group
Subject: Re: ISSUE-189: do regions scroll their flowed content? [DFXP 1.0]

 

 

On Thu, Sep 27, 2012 at 11:15 PM, Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org> wrote:

ISSUE-189: do regions scroll their flowed content? [DFXP 1.0]

 

There is no explicit, automatic mechanism for scrolling content inside a region; however, a note was added to 2nd Edition at the end of 9.3.2 as follows:

 

Where an implementation is able to detect significant similarity between two adjacent synchronic document instances, DOCinterN DOCinterN−1, then it is preferred that the implementation make the transition between presenting the two instances as smooth as possible, e.g., as described by  <http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html#cea608c> [CEA-608-C], § C.3.