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

Re: Discovery of track and named fragment names

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 19 Nov 2009 09:55:51 +1100
Message-ID: <2c0e02830911181455v3b255b10ma0b889c9e08d6588@mail.gmail.com>
To: Davy Van Deursen <davy.vandeursen@ugent.be>
Cc: public-media-fragment@w3.org
Hi all,

It's great to see the topic of ROE come up here.

I am in a similar situation with HTML5 and video accessibility: I
really need to somehow specify what alternative and additional tracks
are available both inside a file and associated external files. I am
eyeing ROE for that, too. It's the same resource discovery problem
that you're facing.

Davy, how did you find working with ROE? Complicated? Or did it give
you what you needed?

Why did you choose ROE and not MPEG-21 DID?

BTW: I don't think we need to solve it in Media Fragments, but we
definitely need to solve it in HTML5.

Also BTW: Michael Dale on metavid is also using ROE but not through a
HTTP alternate resource, but through explicitly including it into the
<video> element. E.g. check out the source code of
http://metavid.org/wiki/Stream:House_proceeding_06-09-08_01/0:01:38/0:10:00
- it looks like this:

<video  id="embed_vid"
poster="..."
roe="http://metavid.org/w/index.php?title=Special:MvExportStream&stream_name=House_proceeding_06-09-08_01&t=0:01:38/0:10:00&amp;feed_format=roe"
...>
  <source timeFormat="anx" type="video/x-flv"
    src="http://mvbox2.cse.ucsc.edu/mvFlvServer.php/house_proceeding_06-09-08_01.flv?t=0:01:38/0:10:00">
  </source>
</video>

The example ROE file is here:
http://metavid.org/w/index.php?title=Special:MvExportStream&feed_format=roe&stream_name=House_proceeding_06-09-08_01&t=0%3A01%3A38%2F0%3A10%3A00


Thanks,
Silvia.

On Wed, Nov 18, 2009 at 11:31 PM, Davy Van Deursen
<davy.vandeursen@ugent.be> wrote:
> Hi all,
>
>
>
> To retrieve track and named fragments, we need to know the name of the
> fragment. Until now, we didn’t talk much about how to discover these names
> (at client side). When implementing scenarios such as [1], I can image that
> a certain way of discovering these names will be necessary.
>
>
>
> In order to discover names of tracks and named fragments, clients can
> download a file describing the organization of the corresponding media
> resource in terms of tracks and named fragments. Formats that can be used
> for this purpose are for example ROE [2], MPEG-21 DID [3], …
>
>
>
> I implemented, by means of an experiment, the ROE format into our NinSuna
> platform [4]. More specifically, if you want to get more information
> regarding the structure of the media resource
> http://schutz.elis.ugent.be:8080/DownloadServlet/fragf2f.ogv, you can
> request this resource through HTTP using ‘application/roe’ in the accept
> header (don’t think this mime type actually exists :-)):
>
>
>
> GET /DownloadServlet/fragf2f.ogv HTTP/1.1
>
> Host: schutz.elis.ugent.be:8080
>
> Accept: application/roe
>
>
>
> The answer includes then the following ROE content (which allows us to
> discover the names of the tracks: ‘ogg_1’ and ‘ogg_2’):
>
>
>
> <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>
>
>
>
> Any comments on this way of working? Moreover, should we specify a method
> for discovering track and named fragments as normative in the spec? I think
> we should have at least an informative section regarding this topic …
>
>
>
> Best regards,
>
>
>
> Davy
>
>
>
> [1]
> http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-reqs/#scenario2.4
>
> [2] http://wiki.xiph.org/ROE
>
> [3] http://www.chiariglione.org/MPEG/technologies/mp21-did/
>
> [4]
> http://www.w3.org/2008/WebVideo/Fragments/wiki/ImplementationExperiment#1._NinSuna_platform
>
>
>
> --
>
> Davy Van Deursen
>
> Ghent University - IBBT
>
> Faculty of Engineering
>
> Department of Electronics and Information Systems
>
> Multimedia Lab
>
> Gaston Crommenlaan 8 bus 201
>
> B-9050 Ledeberg-Ghent
>
> Belgium
>
> t: +32 9 33 14893
>
> f: +32 9 33 14896
>
> t secr: +32 9 33 14911
>
> e: davy.vandeursen@ugent.be
>
> URL: http://multimedialab.elis.ugent.be/dvdeurse
>
>
>
>
Received on Wednesday, 18 November 2009 22:56:52 GMT

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