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

Re: video use-case

From: Jack Jansen <Jack.Jansen@cwi.nl>
Date: Wed, 1 Oct 2008 15:57:46 +0200
Cc: Media Fragment <public-media-fragment@w3.org>
Message-Id: <E0115E6F-7D8F-4849-BA88-1A0FCC519516@cwi.nl>
To: Pierre-Antoine Champin <swlists-040405@champin.net>


On 29 sep 2008, at 14:50, Pierre-Antoine Champin wrote:
>  Variantions of a video fragment
>
> Some video streams (e.g. DVD titles) may be viewed in different  
> versions
> based on user's preferences: different soundtracks, different  
> subtitles
> (if any), sometimes different angles (e.g. live music DVDs). When
> specifying a fragment of those streams, it should be possible to  
> specify
> which variation is considered. However, it should also be possible  
> for a
> fragment to be under-specified with regards to variations: sometimes,
> one would like to address the fragment with a specific soundtrack and
> angle (e.g. "the lips do not move accordingly with the voice"), but
> sometimes a fragment does not depend on a particular variation (e.g.
> "the kiss scene").
>
> (it should be noted that this kind of consideration is somewhat  
> present
> in the "Audio UC's" section... however, I think the problem is even  
> more
> complicated with video)

I think you are assuming here that there is still one single unified  
timeline across the whole video, correct?

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".

I would be happy if we stated somewhere (in <http://www.w3.org/2008/WebVideo/Fragments/wiki/Glossary 
 >?) that our idea of a video is something with a single unified  
timeline, as the image on the glossay page currently also suggests.


--
Jack Jansen, <Jack.Jansen@cwi.nl>, http://www.cwi.nl/~jack
If I can't dance I don't want to be part of your revolution -- Emma  
Goldman
Received on Wednesday, 1 October 2008 13:58:27 GMT

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