W3C home > Mailing lists > Public > public-media-fragment@w3.org > October 2008

Re: video use-case

From: Yannick Prié <yannick.prie@liris.cnrs.fr>
Date: Wed, 1 Oct 2008 23:13:52 +0200
Cc: Media Fragment <public-media-fragment@w3.org>
Message-Id: <C332FC1D-C2E8-40B7-88DE-238FF44D399F@liris.cnrs.fr>
To: Jack Jansen <Jack.Jansen@cwi.nl>

Le 1 oct. 08 à 22:55, Jack Jansen a écrit :

> On 1-Oct-2008, at 17:42 , Pierre-Antoine Champin wrote:
>>> That would be the case for the use cases you explicitly mention  
>>> here,
>>> but there are other multiplexed videos where this isn't the case,  
>>> think
>>> of movies in airline  cut/normal cut/directors cut. This means that
>>> timestamps become messy: either "00h:02m:00s:00f" becomes ambiguous
>>> (could be different points depending on track selection), or  
>>> arithmetic
>>> on timestamps becomes impossible (depending on track selection
>>> "00h:02m:00s:00f" may or may not be 60 seconds after "00h:01m:00s: 
>>> 00f".
>> interesting example, indeed.
>> But, I would rather consider the different "cuts" to be different  
>> videos.
>> Indeed, the timeline is, in my view, a fundamental aspect of a video.
> Agreed. But this triggered another question: are we interested in  
> the timestamps in the movie? If we ask for a segment of video  
> starting at 30s, do we expect the timestamp of the first frame to be  
> "30s"? Do we expect it to be "0s"? Do we expect nothing at all? This  
> is going to be important for client-side creation of URLs for  
> selecting subparts of videos.

I can consider a fragment of a video as a video, and I do not care  
about the architecture that allows me to see it, download it, etc. as  
a video. It begins at 0s.

I can consider a fragment of a video as a fragment of a video. In that  
case it begins at 30s, I can explicitly manipulate both the fragment  
and the video (e.g. jump to a frame before the fragment beginning,  
let's say at 20s).

I think both cases should be considered. I do not manipulate a "video"  
and a "fragment of a video" in the same way, even if their playing can  
result in the same rendering (eg. 5 seconds of video in a web page).



Yannick Prié - MCF Informatique - LIRIS UMR 5205 CNRS
UFR Informatique - Université Lyon 1 - F-69622 Villeurbanne Cedex
Tél: (+33) 4 72 43 16 36 Mél: yprie@liris.univ-lyon1.fr
Fax: (+33) 4 72 43 15 36 Web: http://liris.cnrs.fr/~yprie
Received on Thursday, 2 October 2008 02:08:54 UTC

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