[whatwg] Start position of media resources

[Silvia Pfeiffer]

On Wed, Apr 8, 2009 at 3:30 AM, David Singer <singer at apple.com> wrote:
> At 19:20  +0200 7/04/09, KÞi”tof Îelechovski wrote:
>>
>> OTOH, if the media player scroll bar has zoom function, the problem of
>> navigation deficiency in a short interval disappears.  When the browser
>> displays a fragment, it can just zoom the scroll bar to the fragment
>> displayed.
>> IMHO,
>> Chris
>
> That's a semantic problem I hope that the media fragments group will
> clarify.
>
>  If a URL asks for
>
> http://www.example.com/t.mov?time="10s-20s"
>
> it's clear that all I have at the UA is a 10s clip, so that's what I
> present;  the ? means the trimming is done at the server.

Agreed.


> However, if I am given
>
> http://www.example.com/t.mov#time="10s-20s"
>
> which means the UA does the selecting;  should the UA present a timeline
> representing all of t.mov, but start at 10s into it and stop at 20s,
> allowing the user (if they wish) to seek outside that range, or should the
> UA present (as in the query case) only a 10s clip?

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.

Regards,
Silvia.