[whatwg] Start position of media resources

David Singer singer at apple.com
Tue Apr 7 15:37:43 PDT 2009

At 8:29  +1000 8/04/09, Silvia Pfeiffer wrote:
>  > 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.
>Yes, I understand that analogy. But because video can be a very long
>resource, media fragment URIs cannot be restriced to client-side
>offsetting. Think e.g. about wanting the last 2 minutes out of a 5
>hour discussion downloaded to your mobile phone.
>The media fragment WG decided that fragment addressing should be done
>with "#" and be able to just deliver the actual fragment. (BTW: this
>is in contrast to the temporal URIs that were specified for Annodex,
>where chopping happened in the UA for "#"  and on the server for "?").

But there is a huge difference between

a) the UA MUST optimize for the chosen fragment, and may/should offer 
the rest of the resource to the user (at the possible expense of more 
network traffic)


b) the UA MUST only offer the chosen fragment to the user, and 
optimize network traffic and downloads for just that section, and 
MUST NOT allow navigation outside the indicated range

Unfortunately, it does make a difference to the page author which of 
these is talked about (and, lacking anything else, (a) is probably 
what is expected).
David Singer
Multimedia Standards, Apple Inc.

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