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Re: video aspect use case

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 10 Sep 2009 07:49:45 +1000
Message-ID: <2c0e02830909091449j503c67bat80ae552cfe84a57a@mail.gmail.com>
To: Yves Lafon <ylafon@w3.org>
Cc: Davy Van Deursen <davy.vandeursen@ugent.be>, RaphaŽl Troncy <Raphael.Troncy@cwi.nl>, Philip Jšgenstedt <philipj@opera.com>, public-media-fragment@w3.org
On Thu, Sep 10, 2009 at 6:40 AM, Yves Lafon <ylafon@w3.org> wrote:

> 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).

I disagree. You do not need to transcode an image if you want to display it
with different width and height. It's a user agent thing. I think the same
is true for video aspect ratio.

Received on Wednesday, 9 September 2009 21:50:46 UTC

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