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Minutes of TT WG Teleconference on 09/30/04

From: Thierry Michel <tmichel@w3.org>
Date: Tue, 19 Oct 2004 09:52:41 +0200
To: <public-tt@w3.org>
Message-Id: <20041019075242.CD79B4F48B@homer.w3.org>

Minutes of TT WG Teleconference on 09/30/04


  Glenn Adams (XFSI, Chair, Scribe) [GA]
  Dick Bulterman (CWI) [DB]
  Mike Dolan (invited expert) [MD]
  Sean Hayes, Microsoft (SH)
  David Kirby (BBC) [DK]
  Thierry Michel (W3C) [TM]
  Dave Singer (Apple) [DS]


  Geoff Freed (WGBH/NCAM) [GF]
  Erik Hodge (RealNetworks) [EH]

1. DFXP 3rd Draft Review [1]

[1] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0043.html

[GA] Notes comments received from [DK], [2], and [SH], [3].

[2] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0045.html
[3] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0046.html

(a) tts:origin, etc.

[GA] Indicates new preference for tts:origin and tts:extent rather
than x, y, width, height. No problem w.r.t. list syntax (SMIL, SVG,
XML, etc. make use of various list syntaxes in attr values).

(b) meaning of end time of intervals

[DK] Reminds of need for defining meaning of end time.

[DB] Agrees, on need to define end time precisely and relation to

[GA] We agreed on half open interval, meaning end point is not in
interval. Will specify in understandable (non-mathematic) language.

(c) metadata items

[DK] Reviews comments posted at [4].

[4] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0053.html

[DK] Proposes (1) retain frame-{rate,width,height}, 2) eliminating
pixel-aspect-ratio, (3) express content-{width,height} in pixels (not
(4) replace {horizontal,vertical}-resolution with

[GA] Needs to review proposal. Not sure that pixel-aspect-ratio is not
some authoring contexts.

[GA] Asks about meaning of cells w.r.t. formatting semantics: does this mean
presentation operates in some mode where glyphs are centered in cells?

[DK] Believes this is not the case; intended semantic is to merely
specify initial current position value for subsequent glyph placement
(which would then occur based on font specific metrics).

[GA] This means that there is no guarantee that any glyph but first
glyph will intersect with any cell.  First glyph will intersect with
first cell [and even this is not necessarily guaranteed depending on
placement of glyph outline in font's design coordinate space based
upon current EM square geometry (which is based on font-size

[MD] Expresses mild concern over defining specific metadata items (as
opposed to using a foreign namespace metadata vocabulary, e.g.,

[GA] Believes we can define simple items if doing so satisfies
authorial requirements without introducing excessive complexity that
may be entailed by forcing author to use non-TT-recognized vocabulary.

(d) time expressions

[MD] Concurs with approach of separating SMPTE times as labels
(markers) and media times [as monotonically increasing/decreasing,
continuous time lines]. Should follow limits of SMPTE 12M for
information content of SMPTE time labels. Need to have frame rate
to make any sense out of frame based time specifications.

Action: [MD] Will review and comment on BNF syntax in 3rd draft
for time expressions.

(e) intensional presentation semantics

[GA] During attempt to distill intensional presentation semantics (from
perspective of author) into a set of formal rules, it would appear that
the "combine" attribute is not necessary on regions if one allows the
content flow hierarchy as specified by <body> to govern co-occurrence
in space (formatting region) at an instant in time. Will reflect this
in upcoming 4th draft of DFXP.




Action: [DB] to send draft intro text with example by Monday (10/04).

Action: [MD] to review comment on EBNF syntax of time expressions in
3rd draft.

Action: [GA] to issue 4th draft early next week (by 10/05).


Action: [EH] Provide use cases in TT context for priority class attr

Action: [SH] To elaborate use cases for audio embed usage.

Action: [GA] to generalize and clearly articulate [MD] feedback on XBC
with TT-AF structured timing as use case, then send to WG for review
prior to forwarding to XBC.

Action: [GA] need to document conventions regarding normative definition
of element vocabulary and syntax used therein.

Action: [GA] need to characterize definitions of vocabulary as normative
while supplied schemas are informative.

Action: [GA] review recent proposed changes regarding xml:space from
XML Core Working Group with view of changing our vocabulary definitions
as necessary.

Action: [GA] restore nested <div/> in content model.

Action: [GA] ensure that background color applies to content elements
as well as region.

Action: [GA] change language in vocab element defs that defines equiv
class of attrs in foreign namespace to not admit unqualified attrs.

Action: [GA] need to ensure that we document whether time intervals
are half-opened intervals or closed. We always use half-opened intervals
for [begin,end) = [begin,begin+dur).

Action: [GA] ensure there is language that gives precendence to
end over dur in case both are specified.

Action: [GA] remove region attribute from span element.

Action: [GA], prompted by [SH], need to define what is meant by begin
attribute on <body>.

Action: [KB] lookup whether default time container for SMIL body is
seq or par. Report back by tomorrow (9/16).

Action: [GA] add table indicating default values for timeContainer.

Action: [GA] remove nested <span> support from schema and span
element definition.

Action: [GA] Update schema to permit multiple tts:* attributes on
style element.

Action: [GA] make style attribute IDREFS instead of ID.

Action: [GA] add style attribute to <g/>.

Action: [GA] change region so that it uses style attribute to
refer to styles in addition to defining them inline as children.

Action: [GA] need to establish precedence for different style
association mechanisms as follows, with priority order as follows:
(1) inline, (2) referential or chained referential, (3) region
referential. In case that referential or chained referential results
in a diamond graph, then last instance of style in pre-order depth
first traversal wins.

Action: [SH] will research issue of interaction of combination rule
#2 and region referential styling.

Action: [GA] add <p> and <span> to list of elements to which
background-color applies

Action: [GA] change initial value of color style property to
transparent. [N.B. consequence of this is that unless author
specifies a color, then content will be invisible.]

Action: [GA] restore "inherit" value for style properties.

Action: [GA] specify language about meaning of line height.

Action: [GA] formulate proposal to express coordinates in rows
and columns and to express total # of rows/cols for which content was

Action: [GA] change DFXP schema and WD to use <meta> instead of

Action: [DK] Discuss with [MD] how to express pull-down parameters to
completely characterize frame and field composition.

Action: [GA] need to add following metadata items to schema and spec:
ttm:frame-rate ttm:frame-width ttm:frame-height
ttm:pixel-aspect-ratio ttm:content-width ttm:content-height
ttm:content-x ttm:content-y ttm:horizontal-resolution

Action: [GA] need to specify semantics for each metadata item, need
to specify what it means if multiple items with same name are present
in some context, and if not permitted, expected behavior.

Action: [GA] add definitions of following metadata elements to schema
and spec for DFXP: ttm:agent, ttm:name, ttm:givenName,
ttm:familyName, ttm:actor. Also add ttm:agent attribute to <p> and

Action: [GA] add ttm:title, ttm:description, ttm:copyright to schema
and spec for DFXP.

Action: [GA] ensure that all elements can also take ttm:* attributes,
but need to define in context of specific elements which ones have
standard semantics.

Action: [GA] define semantics of ttm:agent metadata attribute such that
inner specifications override outer specifications, e.g.,

Action: [GA] change text-shadow to text-outline with value syntax as
follows: none | <color> <thickness> <blur-radius>, where thickness and
blur-radius are expressed as <length>.

Action: [GA] add span to wrap-option "applies to".

Action: [GA] for each AFXP style property that we don't include in DFXP,
need to specify a normative default value for DFXP, but do so in a way
that doesn't require normative use of AFXP specification.

Action: [GA] since <color>s are opaque, need to say so in verbiage.

Action: [GA] Remove misspelled "monotype" entry from <generic-family-
name>, and replace it with "default". All other entries are also to be
removed for present time.

Action: [GA] Add row/col units to <length> style value expression.

Action: [GA] Ensure that if we define overflow="clip" on region that
we say that outermost region is expected to be clipped in all cases.

Action: [GA] change overflow attribute on region to use tts:overflow
style property, which applies only to region, and which supports values:
visible, hidden, inherit.

Action: [GA] Change clock-value syntax to support expressing optional
frames and subframes in order to express NPT media times. Define clock
value semantically to be NPT for TT media object. Remove optional "+"
value from offset-expression (in which case we don't need "offset-
expression" intermediate term).

Action: [GA] allow style to use style attribute to refer to other
styles, since we effectively now allow <style> to work like a group of

Action: [GA] remove "div" from display-align's applies to list. Can't
apply to div since div has no explicit height/width.

Action: [GA] Add ttm:default-time-metric metadata item. Takes
values that are one of time-count metric, e.g., "h", "m", "s",
"f", etc.

Action: [GA] send John's document to WG reflector, then (at some point
in future) ask him to send to public list so it can be handled as public

Action: [GA] Add informative Annex to DFXP spec which enumerates the
requirements of TT-AF-1-0-REQ which are intentionally not intended to
be met in DFXP.

Action: [KB] Review the March 2002 TT Task Force requirements to see if
the current TT-AF-1-0-REQ does not include all those earlier requirements,
and if not, then make a case for including in TT-AF-1-0-REQ. [TM] will
help as required and report back to WG.

Action: [DB] to send draft intro text with example by Monday (10/04).

Action: [MD] to review comment on EBNF syntax of time expressions in
3rd draft.

Action: [GA] to issue 4th draft early next week (by 10/05).


See Issue DB.

*** Upcoming Meetings ***

Normal Telecon Schedule

11/30 - 12/02 Reading, UK (Tentative; MSFT hosting)

*** URIs ***

[1] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0043.html
[2] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0045.html
[3] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0046.html
[4] http://lists.w3.org/Archives/Member/member-tt/2004Sep/0053.html

Received on Tuesday, 19 October 2004 07:52:45 UTC

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