[whatwg] Start position of media resources

David Singer singer at apple.com
Tue Apr 7 15:21:35 PDT 2009

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

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.

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