W3C home > Mailing lists > Public > public-media-fragment@w3.org > September 2009

RE: video aspect use case

From: Yves Lafon <ylafon@w3.org>
Date: Wed, 9 Sep 2009 16:40:56 -0400 (EDT)
To: Davy Van Deursen <davy.vandeursen@ugent.be>
cc: 'RaphaŽl Troncy' <Raphael.Troncy@cwi.nl>, 'Philip Jšgenstedt' <philipj@opera.com>, public-media-fragment@w3.org
Message-ID: <alpine.DEB.1.10.0909091640090.8146@wnl.j3.bet>
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).

Baroula que barouleras, au tiťu toujou t'entourneras.

Received on Wednesday, 9 September 2009 20:41:07 UTC

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