At 8:02 +1000 8/04/09, Silvia Pfeiffer wrote:
Note that in the Media Fragment working group even the specification
of http://www.example.com/t.mov#time="10s-20s"; may mean that only the
requested 10s clip is delivered, especially if all the involved
instances in the exchange understand media fragment URIs. During a
transition period, while the infrastructure does not support media
fragment URIs yet, the full resource will be delivered and it is up to
the UA to deal with the consequences. It could either terminate the
connection and decide that the resource is too long to accept and
report an error to the user. Or it could receive the full resource,
but decide to just play back the requested segment. Since ultimately
the aim is to have only the requested clip downloaded, I think the UI
presentation should be identical to the one where a query is used.
BTW: the media fragment WG will make suggestions as to what a UA
should do, but ultimately every application may have its own
motivations for what to display, so you will not see definite
specifications for what a UA is supposed to do UI-wise with media
fragments. Think, e.g., about a playlist that consists of fragments
from multiple Web resources (including different servers). Such a
mash-up should probably best be represented with on continuous
timeline that overrides the original timing of each clip. Only when
you drill into the clip will you actually get the original in and out
times.
Ah, OK. I agree that telling UAs what they should do, ought to be
for the most part, out of scope. But if there is material that the
page author does NOT want to have shown, they probably need to know
whether the # syntax will assure them that the user is restricted.
(Always understanding that if they copy-paste the URL, neitehr # nor
? syntax stops them from changing the selection range). Think of
presenting a K-12 class with a clip from a movie...
My mental analogy was HTML, where an acnhor takes you to that part of
the page as a convenience, but nothing stops you from navigating
away. And in the case where the UA optimizes for showing that
section (by suitable handshakes/translations with the server), again,
it could present a UI which offers other times -- at the expense of
more handshakes.
--
David Singer
Multimedia Standards, Apple Inc.
