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
> [CEA-608-C]<http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html#cea608c>,
> § C.3.****
>
> ** **
>