W3C home > Mailing lists > Public > public-tt@w3.org > March 2005

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

From: <Johnb@screen.subtitling.com>
Date: Thu, 17 Mar 2005 14:53:28 -0000
Message-ID: <11E58A66B922D511AFB600A0244A722EE57D86@NTMAIL>
To: public-tt@w3.org
As defined, the use of referential styles already requires head fragments to
be repeated throughout a stream transmission to permit mid-stream
acquistition. A stream unit is not directly parsable if it uses referential
styling, because it will require lookup in this 'head' fragment.
So it would seem that the sole reason for not including class based (or rule
based) styling is the need for "re-evaluating all rules for each content
unit that arrives".
I am not personally convinced that this is more onerous than supporting a
referential style... YMMV ! 
Not including this feature in DFXP does make restyling of DFXP content
somewhat more onerous.... since any relationship between a role and a style
will be lost by transition into DFXP. Consequently, this mandates the use of
AFXP for exchange and pre-distribution storage if the intention is to
support these relatively minor 'presentation' changes at output time.
I may seem to be 'pedantic' on this point, but one of the major limitations
of existing formats is that they do not support easy transitions between
real on the wire distribution formats - where the distribution formats do
not provide equivalent support for presentation options - simply because
they also do not convey this connection between style and role. If there is
no connection between the role / agent metadata and the style in DFXP - then
there is little point in including the role and agent metadata IMHO. This is
because in order to support the conversions that would be anticipated, the
style mechanism would have to also carry the role aspect as part of the
style ID.... thus creating an explosion in style definitions. Further, each
fragment of content that required identification would need to carry a style
IMHO In this aspect, DFXP is too cooked. I prefer mine raw!
regards John Birch.

-----Original Message-----
From: Glenn A. Adams [mailto:gadams@xfsi.com]
Sent: 17 March 2005 14:02
To: Johnb@screen.subtitling.com; public-tt@w3.org
Subject: RE: Timed Text Authoring Format - Distribution Format Exchange Pr
ofile (DFXP)

Actually, DFXP does not support out-of-line styling in the traditional sense
(e.g., CSS sense). The fact that one can place style specifications in
<head/> and share their use among multiple content elements is merely an
optimization of expressing inline styles (by reference). We call this
referential styling.


What you are requesting is a form of rule based applicative styling that
applies independent style rules to content based on matching criteria. This
mechanism will be defined in AFXP, but was explicitly ruled out for DFXP
since it requires either (1) having all content available to apply rules to,
or (2) repeatedly re-evaluating all rules for each content unit that arrives
(e.g., in a streaming scenario).


The basic model for DFXP is completely inlined styles, but the referential
styles were defined as an optimization to allow:


(1)     aggregation and sharing of common inline styles

(2)     pre-delivery or separate packaging of a fragment containing
referential styles from fragments containing content


The decision to simplify DFXP was based on the desire that DFXP content be
more concrete and directly parsable/renderable in a potential streaming
context. The general use of out-of-line applicative style rules is
antithetical to this approach.





From: Johnb@screen.subtitling.com [mailto:Johnb@screen.subtitling.com] 
Sent: Thursday, March 17, 2005 7:56 AM
To: public-tt@w3.org
Subject: RE: Timed Text Authoring Format - Distribution Format Exchange Pr
ofile (DFXP)


Glenn, et al, 

The DXFP specification includes support for styling, both in-line and
out-of-line styling. 
However it does not support a class based styling model. 

In subtitling, styles are most often associated with changes in the text
'role' (e.g. dialogue differs in presentation from music) or 'speaker' (Joe
- red, Frank - blue).

Could a mechanism be added to support this? 

E.g. This might be represented in DXFP by utilising a class based style
mechanism that was sensitive to ttm:role and ttm:agent. Thus:

<style id="s1" style tts:color="white" tts:fontFamily="monospace-serif"/> 
<style id="intro" style="s1" tts:fontSize="4%"/> 
<style id="documentary" style="s1" tts:fontSize="10%"
<style id="music" ttm:role="music" tts:fontStyle="oblique"/> 
<style id="joe" ttm:agent="joe" tts:color="red"/> 

<div style="intro"> 
<!-- all text 4% high --> 
<!-- all text monospace-serif --> 
<p ttm:role="music">Quiet Violin music</p> 
<div style="documentary"> 
<!-- all text 5% high --> 
<!-- all text sans-serif --> 
<p>White Large sans-serif</p> 
<p ttm:role="music">White Oblique Large sans-serif</p> 
<p ttm:agent="joe">Red Large sans-serif</p> 

the ttm:role and ttm:agent attributes could be considered as implicitly
adding inline style attribute(s) to their container....


John Birch 
Senior Software Engineer, 
Screen Subtitling Systems Limited, 
The Old Rectory, Claydon Church Lane, 
Claydon, Ipswich, Suffolk. 
Tel: +44 1473 831700 
Fax:+44 1473 830078 

See us at NAB Las Vegas April 18-21st Stand No. SU8956 

This message is intended only for the use of the person(s) ("the Intended
Recipient") to whom it is addressed. It may contain information which is
privileged and confidential within the meaning of the applicable law.
Accordingly any dissemination, distribution, copying or other use of this
message or any of its content by any person other than the Intended
Recipient may constitute a breach of civil or criminal law and is strictly
prohibited. If you are not the Intended Recipient please destroy this email
and contact the sender as soon as possible.

In messages of non-business nature, the views and opinions expressed are the
author's own and do not necessarily reflect the views and opinions of the
Screen Subtitling Systems Limited.

Whilst all efforts are made to safeguard Inbound and Outbound emails, we
cannot guarantee that attachments are Virus-free or compatible with your
systems and do not accept any liability in respect of viruses or computer
problems experienced.

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

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


The TT WG solicits your comments on this new draft as soon as possible, 
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 14:38:19 UTC

This archive was generated by hypermail 2.3.1 : Thursday, 5 October 2017 18:24:01 UTC