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Re: Identifying vs Describing media URI fragments

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 24 Sep 2008 08:21:54 +1000
Message-ID: <2c0e02830809231521v2461a1adq5d34f949c874db09@mail.gmail.com>
To: "RaphaŽl Troncy" <Raphael.Troncy@cwi.nl>
Cc: "Media Fragment" <public-media-fragment@w3.org>

Hi Raphael,

I think our problem is that we have to do one (fragment specification)
to allow for the other (fragment linking). A further problem is
whether we just do fragment specification or go all the way to
fragment identification (through naming).

For some things, the fragment specification & naming are obivous or
already available - not so for others.

* image fragments can already be specificed through image maps and
giving the map an id, so we have both, a region specification, and a
naming mechanism to refer the region fragment with.

* temporal fragments for audio or video can also easily be specified
through a <start,duration> or <start,end> tuple, even though the Web
currently has no such thing; naming such fragments OTOH hasn't been
defined yet from a format POV.

* spatio-temporal fragments for video are more complicated and haven't
got a specificaiton yet. A suggestion could be a image map at the
start, a image map at the end, and a function to move from one to the
other. How to give this a name is another matter.

I think part of the mandate of this group is to solve the fragment
specification issue. If we cannot specify it, we cannot link to it.

Whether the naming is part of our mandate is a different issue and I
only added it to the wiki because somebody else had already spoken
about global identifiers for RDF purposes. I think this problem will
have to be solved at some point. Whether we decide that it is close
enough to our problem to take it on as well or leave it to another
time to solve, I'm fairly indifferent.

My suggestion would be to define the URI mechanism for linking to such
named fragments, because it's fairly simple. But to leave the actual
problem of how a media container translates the name to a segment of
media data to the media container controlling entities (Apple for
QuickTime, Xiph for Ogg, MS for wmv etc).

In fact, this is the only thing we can do for temporal and spatial
fragments, too. But let's have that discussion later.


On Wed, Sep 24, 2008 at 4:50 AM, RaphaŽl Troncy <Raphael.Troncy@cwi.nl> wrote:
> Dear all,
> I would like to start a discussion on this topic that could further precises
> the scope of a media URI fragment specification. I would distinguish the
> identification versus the description of a media URI fragment.
> The identification refers to the syntax with which we construct a fragment
> URI. The description refers to the semantics of this fragment. Silvia
> proposed in the Media Annotation UC [1] the possibility to label a fragment
> (e.g. the kiss scene) for being able to refer to. Is this label still an
> identification of the fragment or a description? Do we consider that
> describing a media fragment is out of scope of this WG?
>  RaphaŽl
> [1]
> http://www.w3.org/2008/WebVideo/Fragments/wiki/Use_Cases_%26_Requirements
> --
> RaphaŽl Troncy
> CWI (Centre for Mathematics and Computer Science),
> Kruislaan 413, 1098 SJ Amsterdam, The Netherlands
> e-mail: raphael.troncy@cwi.nl & raphael.troncy@gmail.com
> Tel: +31 (0)20 - 592 4093
> Fax: +31 (0)20 - 592 4312
> Web: http://www.cwi.nl/~troncy/
Received on Tuesday, 23 September 2008 22:22:32 UTC

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