slicing coordinates for multimedia

There has been some discussion[1] on the uri list of "fragment"
syntax for slices of multimedia composites, which the MPEG 21 working
team had been considering expressing in #fragment syntax as with
applications of XPointer.

They may feel that the social side of establishing a community
consensus across language proponent groups may be too daunting and
just do something in the name of a specification to be used inside
MPEG integration documents. If they do this, it could be a setback
for the vision of the Web as one great commons, and at the very least
a setback for disability access to information represented as
multimedia composites[2].

The alternative would be to have some sort of agreement among
multiple constituencies such as MPEG 21, SMIL, X3D, and the like on a
convention for expressing slices of composites (including reaching
into constituents) in terms of the coordinates of the composite. And
possibly what those default composite-frame coordinates are, but the
latter might vary by integration format.

This applies to multimedia canvases as contemplated by SMIL and CSS
and more generally to virtual worlds[2] as contemplated by X3D. I
believe that we can treat the virtual world as an absorbing model
that covers the multimedia canvas. MMI and screen-reader worlds are
possibly yet more general involving a sheaf of sub-worlds (view
tuple, deck of WAP1 cards, for example).

The accessibility argument is roughly that AT for VR and multimedia
needs the capability to break the composite down, either
componentwise or by slicing, until a slice is obtained that is
conformable to an interaction world in which the user is comfortable
and their motion within this world is securely under their control.
Then they need view controls to sweep or navigate this slice around
to cover the entire problems-space world. AT doesn't have the kind of
resources to do this for multiple arbitrary conventions as to slicing
coordinates in the composite experience world. But AT might be
economic if there were a reasonable convention such that navigation
and slicing in standard coordinates would be effective across all
formats in this class.

Al

[1] Thread on uri at w3.org list
http://lists.w3.org/Archives/Public/uri/2004Jul/thread.html#2

[2] Workshop on access to visualization - please see my contributions
http://www.w3.org/WAI/RD/2004/06/28-agenda.html

Received on Wednesday, 21 July 2004 10:22:38 UTC