- From: David Singer <singer@apple.com>
- Date: Tue, 27 Jan 2009 15:48:31 +0100
- To: Michael Hausenblas <michael.hausenblas@deri.org>
- Cc: Media Fragment <public-media-fragment@w3.org>, Raphaël Troncy <Raphael.Troncy@cwi.nl>
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 14:50:56 UTC