W3C home > Mailing lists > Public > whatwg@whatwg.org > July 2008

[whatwg] HTMLMediaElement: more issues and ambiguities

From: Philip Jägenstedt <philipj@opera.com>
Date: Thu, 10 Jul 2008 12:16:52 +0700
Message-ID: <1215667012.6542.57.camel@localhost>
Thanks for addressing all of my questions, there is only one issue below
which I think deserves a second round.

On Wed, 2008-07-09 at 00:05 +0000, Ian Hickson wrote:
> On Thu, 3 Jul 2008, Philip J?genstedt wrote:

> > http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#adjusted
> > 
> > "If the video's pixel ratio override's is none, then the video's 
> > intrinsic width is the width given by the resource itself. If the video 
> > has a pixel ratio override other than none, then the intrinsic width of 
> > the video is the width given by the resource itself, divided by the 
> > pixel ratio given by the resource itself, multiplied by the video's 
> > pixel ratio override."
> > 
> > ?This is a pixel ratio *override*, suggest changing it to:
> > 
> > "?If the video's pixel ratio override's is none, then the video's 
> > intrinsic width is the width given by the resource itself ?multiplied 
> > by the pixel ratio given by the resource itself. If the video has a 
> > pixel ratio override other than none, then the intrinsic width of the 
> > video is the width given by the resource itself multiplied by the 
> > video's pixel ratio override."
> 
> The idea is that if you set the override to a 1:2 ratio, then each pixel 
> of video data will be rendered 1:2. So you first have to normalise the 
> width, getting rid of the influence of the "official" pixel ratio. No?

I understand what the intention is, but think the terminology is
confusing:

- width given by the resource itself
- height given by the resource itself
-? pixel ratio given by the resource itself

I had thought that these 3 were actually orthogonal, such that the pixel
ratio does not affect the width or the height. Instead, it seems that
width/height is supposed to be aspect ratio pre-multiplied. This doesn't
sit well with my intuition of what the "self-given" width/height of
video is supposed to mean. If you open video in common media players the
"dimensions" or "width/height" will be the physical width/height, not
aspect-corrected width/height. Unless my intuition is severely broken, I
think other will also assume what I have assumed.

So again, I suggest that the paragraph be changed:

If the video's pixel ratio override's is none, then the video's
intrinsic width is the width given by the resource itself ?multiplied by
the pixel ratio given by the resource itself. If the video has a pixel
ratio override other than none, then the intrinsic width of the video is
the width given by the resource itself multiplied by the video's pixel
ratio override.

Yes, it implicitly redefines "?width/height given by the resource
itself" to mean what they sound like. Strictly this really only matters
to implementors, but less confusing language is good. Incidentally it is
more in line with how it would actually be implemented -- one would
hardly waste floating point calculations by multiplying by pixel ratio,
dividing by pixel ratio and then multiplying it by override pixel ratio.

-- 
Philip J?genstedt
Opera Software
Received on Wednesday, 9 July 2008 22:16:52 UTC

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