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Re: video size when aspect ratio is not 1

From: Ian Hickson <ian@hixie.ch>
Date: Mon, 14 Sep 2009 06:48:59 +0000 (UTC)
To: Philip Jägenstedt <philipj@opera.com>
Cc: Simon Pieters <simonp@opera.com>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <Pine.LNX.4.62.0909140637430.14605@hixie.dreamhostps.com>
On Thu, 3 Sep 2009, Philip Jägenstedt wrote:
> On Thu, 03 Sep 2009 13:47:41 +0200, Ian Hickson <ian@hixie.ch> wrote:
> > On Mon, 31 Aug 2009, Simon Pieters wrote:
> > > 
> > > The following paragraph:
> > > 
> > > "The intrinsic width and intrinsic height of the media resource are 
> > > the dimensions of the resource in CSS pixels after taking into 
> > > account the resource's dimensions, aspect ratio, clean aperture, 
> > > resolution, and so forth, as defined for the format used by the 
> > > resource."
> > > 
> > > ...doesn't say whether to scale up or down when taking into account 
> > > aspect ratio.
> > 
> > Wouldn't that be up to the video format?
> 
> No, video formats only give the size in pixels and the pixel aspect 
> ratio (or alternatively frame aspect ratio). The only constraint is that 
> the aspect ratio be correct, which forces us to choose how to achieve 
> that. Assuming one dimension remains unchanged:
> 
> 1. always scale up
> 2. always scale down
> 3. always scale x-dimension
> 4. always scale y-dimension
> 
> We're suggesting #1. From the rest I've only seen #3 used in actual 
> media players.

Fair enough. I've specced #3 (#3 and #4 are simpler to implement than #1 
or #2, and the extra complexity doesn't seem to gain us much. I've never 
heard of anamorphic video data with a ratio less than 1.0, so assuming my 
experiences are representative, it's the same as #1 in most cases anyway).

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Monday, 14 September 2009 06:44:14 GMT

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