W3C home > Mailing lists > Public > public-media-fragment@w3.org > March 2009

Re: Use Cases and Requirements Wiki page updated

From: Guillaume Olivrin <golivrin@meraka.org.za>
Date: Wed, 11 Mar 2009 17:46:28 +0200
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Cc: Media Fragment <public-media-fragment@w3.org>
Message-Id: <1236786388.6521.54.camel@video-lab>
Hello Silvia, 

> Use Case 2.4 (really: 3) Spatial Video Pagination - Guillaume, can you
> explain how that is spatial pagination? I don't quite understand what
> Elaine is actually doing with the video.
Ok, let me try again:
The idea of "spatial pagination" is to cut a video image into areas,
then play each area as a full video, one after another. 

For example, Elaine has a video mozaic which shows 4 channels. In her
original video, all 4 channels are synchronised and playing at the same
time, each occupy a quarter of the screen. Now Elaine wants to see all 4
channels "full screen", one channel at a time.
With the help of Media Fragments she selects in her original video each
one of the 4 video regions separately, and then queues each new video
fragments into a playlist. Now she can watch each video region
separately and sequentially. 

> Use Case 4.5 Search Engine - I don't understand how that fits within
> the section. The section is about annotating, but this one essentially
> just re-describes what was already described in Use Case 1.1 Search
> Engine. Can you explain where you see the annotations coming in?

I guess it's the same as UC 1.1 and we can remove UC 4.5.
I can't really justify why it would make a different use case. 
A typical Web search engines will return a Media Fragment URI if this
URI has been used in context of the Keyword e.g. In Web context : <a
href="mymediafragment.ogv">This is a nice Bike</a>
UC 4.5 is just a case of RDF or MPEG7 annotation schema, which Search
Engines will learn to retrieve URI from eventually just like they do
from HTML. 

> I wonder if Use Cases 5.3 and 5.4 are out of scope.
These two UCs, it is true, are not really covered in the 'Model of a
Video Resource' diagram as it is now.
It is not a case of Time, nor Space, nor Track selection but rather a
case of Frame selection.

Another hybrid case, that of animated GIFs : we can use time= so select
a specific "time portion" of a GIF. But do we want to be able to select
a specific image/frame out of GIF? The semantics are different.

Would it be technically difficult to cover these cases ?
These UCs do have very practical applications in mind, but they may fall
more under initiatives such as the WebCGM ...

As it is, we haven't worked on addressing these cases in the syntax
either. So maybe we should mark them 'out of scope' a posteriori. This
could be work for a later stage and another release of Media Fragments.

Thank you Silvia for including all the UCs in the draft.
Should we now reflect these changes you've suggested in both Wiki and

Received on Wednesday, 11 March 2009 15:55:00 UTC

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