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Re: Discovery of track and named fragment names

From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Date: Mon, 23 Nov 2009 22:45:18 +0100
Message-ID: <4B0B026E.2080704@cwi.nl>
To: Davy Van Deursen <davy.vandeursen@ugent.be>, public-media-annotation@w3.org
CC: "'Silvia Pfeiffer'" <silviapfeiffer1@gmail.com>, public-media-fragment@w3.org
Dear Davy, Media Annotations WG,

*Background:* the Media Fragments WG is interested at this stage in 
listing all the technologies that enable track and named fragments 
discovery, i.e., the UA has a way to know for example which tracks are 
available in a particular media file.

Davy has hacked a nice prototype using the ROE format [1]. Hence, the 
following HTTP request:

GET /DownloadServlet/fragf2f.ogv HTTP/1.1
Host: schutz.elis.ugent.be:8080
Accept: application/roe

returns a ROE description of the media file 'fragf2f.ogv'.
This ROE description will look like:
<ROE xmlns="http://www.xiph.org/roe1.0">
   <body>
     <track id="ogg_1" provides="video">
       <mediaSource id="ogg_1_source" content-type="video/theora" 
src="http://schutz.elis.ugent.be:8080/DownloadServlet/fragf2f.ogv?track='ogg_1'" 
/>
     </track>
     <track id="ogg_2" provides="audio">
       <mediaSource id="ogg_2_source" content-type="audio/vorbis" 
src="http://schutz.elis.ugent.be:8080/DownloadServlet/fragf2f.ogv?track='ogg_2'" 
/>
     </track>
   </body>
</ROE>

So the UA can now request one of the two tracks available.

*Question:* Could the ma:fragments and ma:namedFragments properties be 
used to enable track and named fragments discovery?

> DOMString[] getTrackNames(MediaResource mr) {
> 	Fragment[] fragments = mr.fragments();
> 	DOMString[] tracknames;
> 	for(Fragment f : fragments) {
> 		If(f.role = "Track") {
> 			tracknames.add(f.identifier);
> 		}
> 	}
> 	return tracknames;
> }
> 
> Does this makes sense or am I completely misusing the fragments() function
> here :-)?

Could we make such a use of the Media Ontology API for solving our problem?
Best regards.

   RaphaŽl

[1] http://wiki.xiph.org/index.php/ROE

-- 
RaphaŽl Troncy
EURECOM, Multimedia Communications Department
2229, route des CrÍtes, 06560 Sophia Antipolis, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.eurecom.fr/~troncy/
Received on Monday, 23 November 2009 21:46:08 GMT

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