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RE: video aspect use case

From: Davy Van Deursen <davy.vandeursen@ugent.be>
Date: Thu, 10 Sep 2009 07:16:54 +0200
To: "'Yves Lafon'" <ylafon@w3.org>
Cc: 'RaphaŽl Troncy' <Raphael.Troncy@cwi.nl>, 'Philip Jšgenstedt' <philipj@opera.com>, <public-media-fragment@w3.org>
Message-ID: <001d01ca31d5$e9b308a0$bd1919e0$@vandeursen@ugent.be>
> -----Original Message-----
> From: public-media-fragment-request@w3.org [mailto:public-media-
> fragment-request@w3.org] On Behalf Of Yves Lafon
> Sent: woensdag 9 september 2009 22:41
> To: Davy Van Deursen
> Cc: 'RaphaŽl Troncy'; 'Philip Jšgenstedt'; public-media-fragment@w3.org
> Subject: RE: video aspect use case
> 
> On Wed, 9 Sep 2009, Davy Van Deursen wrote:
> 
> >>> I've
> >>> only been able to understand it as forcing the aspect ratio of the
> >>> resource, rather than somehow modifying the resource (i.e. the
> exact
> >>> same bytes should be sent).
> >>
> >> Well, not exactly. Converting formats of unequal ratios is done by
> >> either cropping the original image to the receiving format's aspect
> >> ratio (zooming), by adding horizontal mattes (letterboxing) or
> vertical
> >> mattes (pillarboxing) to retain the original format's aspect ratio,
> or
> >> by distorting the image to fill the receiving format's ratio.
> Depending
> >> on the strategy, if done on server side, the server will not serve
> the
> >> exact same bytes ... and possibly save some bandwidth (needs to be
> >> measured though!)
> >
> > In my opinion, different aspect ratio's of a media resource are
> different
> > 'versions' of one media resource and not different 'fragments'. You
> can
> > compare it with spatial scaling: as much as possible is done to
> preserve the
> > full content of the media resource. The latter is not the case with
> > fragments, where you select specific things of the media resource. So
> > shouldn't we just drop the aspect identifier?
> 
> Well, that's the crux of the issue of using ? vs # in case of
> transcoding
> (and in the aspect ratio UC, it's quite likely to require transcoding,
> with the existing formats).

What I wanted to say is that, in my view, a different aspect ratio of a
media resource is not a fragment (but a version). Since our task is to
identify media fragments, I think aspect ratio is out of our scope.
Similarly, we do not consider spatial, quality, or temporal scaling.

Best regards,

Davy

--
Davy Van Deursen

Ghent University - IBBT
Department of Electronics and Information Systems Multimedia Lab
URL: http://multimedialab.elis.ugent.be
Received on Thursday, 10 September 2009 05:18:16 GMT

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