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Re: ISSUE-2: What is the mime type of a media fragment? What is its relation with its parent resource?

From: Michael Hausenblas <michael.hausenblas@deri.org>
Date: Tue, 27 Jan 2009 15:15:39 +0000
To: Yves Raimond <yves.raimond@gmail.com>, David Singer <singer@apple.com>
CC: Media Fragment <public-media-fragment@w3.org>, RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Message-ID: <C5A4D59B.14AA%michael.hausenblas@deri.org>


Yves,

Good point re FRBR. I'd also target FRBR manifestations but I fear we will
need end up with FRBR items.

Cheers,
      Michael

-- 
Dr. Michael Hausenblas
DERI - Digital Enterprise Research Institute
National University of Ireland, Lower Dangan,
Galway, Ireland, Europe
Tel. +353 91 495730
http://sw-app.org/about.html


> From: Yves Raimond <yves.raimond@gmail.com>
> Date: Tue, 27 Jan 2009 15:10:54 +0000
> To: David Singer <singer@apple.com>
> Cc: Michael Hausenblas <michael.hausenblas@deri.org>, Media Fragment
> <public-media-fragment@w3.org>, RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
> Subject: Re: ISSUE-2: What is the mime type of a media fragment? What is its
> relation with its parent resource?
> 
> On Tue, Jan 27, 2009 at 2:48 PM, David Singer <singer@apple.com> wrote:
>> 
>> At 14:36  +0000 27/01/09, Michael Hausenblas wrote:
>>> 
>>> Dave,
>>> 
>>> 
>>>>  a) the MIME type of the requested fragment is the
>>>>  same as that of the original resource;  yes, that
>>>>  might result in one-frame movies, and so on;
>>> 
>>> Sounds good. Didn't think about this one yet. But how do we technically do
>>> this? I fear I don't understand. Could you be more precisely on this
>>> option,
>>> please?
>>> 
>> 
>> Well, I am trying hard to think of a case *in multimedia* where the
>> statement
>> "the type of a piece of X *cannot* be the same as the type of X"
>> would be true.
>> 
>> The obvious problem area is if you select a time-point in a video track of a
>> movie, then a fragment cast as a movie would have zero duration -- it's more
>> sensibly a picture.  Unfortunately, zero duration frames are explicitly
>> forbidden in MP4, 3GP etc. (since they can make the visual display at a
>> given time ambiguous).
>> 
>> But this gets semantically tricky if there is sound;  what is the correct
>> representation of a point in time of a sound track?  It's not right to drop
>> it from the fragment (oof, we'd need media-type rules for what types get
>> dropped and what don't).
>> 
>> This is steering me towards wondering if a piece of X, in time, necessarily
>> has some extension in time, i.e. a time-point is not a fragment (can you see
>> a zero-width character if you meet one in the street?).
> 
> I think that raises lots of really interesting questions, and
> highlight the need for a debate about what a media fragment actually
> is. Is it a bunch of byte (in that case, it makes sense to associate a
> mime-type with it), or is it an identifier for a piece of the content?
> In other words, does it identify a FRBR item, or a FRBR manifestation?
> I would personally go for the latter, which would allow us to use
> media fragments for identifying a particular signal sample, a frame in
> a video, etc.
> 
> Best,
> y
> 
> --
> Yves Raimond
> BBC Audio & Music interactive
> http://moustaki.org/
Received on Tuesday, 27 January 2009 15:16:41 GMT

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