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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: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 28 Jan 2009 09:45:28 +1100
Message-ID: <2c0e02830901271445x2a2844a0te67d8f947b55f29c@mail.gmail.com>
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>

I agree with Dave - the only problem where we are potentially changing
mime types is the request for a picture out of a video. We should
focus on this discussion. And.. no, I haven't got a good answer yet.


On Wed, Jan 28, 2009 at 1:48 AM, 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?).
> --
> David Singer
> Multimedia Standards, Apple Inc.
Received on Tuesday, 27 January 2009 22:46:06 UTC

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