re: timed-text , simple and soon

I have been reading the comments in this list for a while now - and thought
I might drop in :-)

I work for a company that produces software for the production of subtitles
for broadcast television. At present within this area the standards used are
either proprietary or where open and ratified, are interpreted in different
ways. Consequently there is no 'real' standardisation or compatibility
across the products from various vendors.

I was interested to read the comment "timed-text, simple and soon"...
particularly in conjunction with the draft requirements
http://www.w3.org/AudioVideo/timetext.html.

For our market area  - the primary requirements for a timed text standard
are 
1. that it is language agnostic,
2. that it includes a rigid synchronisation mechanism against an absolute
time (not relative to start or other elements).
3. that it includes the ability to markup elements of text so their content
may be identified.

The requirements draft makes the following comment:

	16. Use markup to clearly distinguish one speaker from another. This
could be accomplished by a) using simple placement commands (<center>,
<left>, <right>, etc.); or b) creating a persona for text which is spoken by
each speaker using speaker="IDREF" attribute

In our industry (subtitling) there is a considerable variation in the use of
presentation to impart extra meaning to the text. As a non exhaustive list,
presentation style (font, size, colour and positioning) is used to denote
speakers, the location of the speaker, the mood of the speaker, sounds (i.e.
non speech) e.g. CAR HORN!, the playing of music...... etc.

I do not believe it would be a good idea to use placement (or other styling)
elements in the timed text standard as a means of speaker identification, it
would be preferable to use some type of tagging mechanism to identify the
content of the text e.g. <Title>, <Speaker1>, <Audio Description1>,
<Narrative>, <Sound> etc. The actual presentation 'style' of these elements
should then be the responsibility of a separate mechanism to impose style on
the timed text content, and may in part be player dependent. Positioning,
placement and all other issues of presentation would then be a matter of
interpretation of the tags (if desired) and a corresponding (if provided)
'style sheet'. This fits well with the subtitling industry - where the
'style' for the presentation of the subtitles is often set by the
broadcaster - not the originator of the subtitles.

However, there are forms of subtitling that are problematic to implement
without **some** mechanism for controlling placement. One 'form', called
'snake', adds words piecemeal to the ends of subtitle rows as they are
spoken. When a row fills it moves up. This form of subtitling treats the
'display' in a similar manner to an 'old style' terminal. A similar form of
subtitling occurs in Teletext with add-on subtitles. In both cases the
previous partial subtitle must remain on screen when the next one appears
(typically a new subtitle replaces the previous one). This could be achieved
by issuing sequences of 'placed' text elements, where each subsequent
element replaces the previous one and includes a larger proportion of the
complete subtitle. However this would be inefficient for a streamed
implementation. These forms of subtitling might be better supported by using
a tagging mechanism that can identify text as being a part of a larger
composite text element (but where each fragmenthas its own distinct
presentation time).

I realise that many of these comments are 'ahead of the gun' so to speak,
however I do feel that clause 16 might be better stated as

16. Include a mechanism to identify the content(?type) of the text element.

regards 

	John Birch
	Senior Software Engineer

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