[whatwg] Change request: rules for pixel ratio

Philip Jägenstedt philipj at opera.com
Wed Jun 11 00:41:53 PDT 2008

On Tue, 2008-06-10 at 10:48 -0700, Ralph Giles wrote:
> Does this mean the implementation must retrieve the self-described  
> pixel aspect ratio from the stream and supply it as part of the DOM?

Yes, the implementation would read the pixel ratio from the video
stream. In libtheora this is aspect_numerator/aspect_denominator of the
th_info struct (yes, this is pixel ratio, not frame aspect ratio). This
would all be handled by some multimedia framework anyway, so most
browsers won't have to worry too much about such details.

Exposing pixel ratio as readonly float videoPixelRatio in
HTMLVideoElement might be a good idea. If the media resource doesn't
self-describe its pixel ratio (many formats don't) it should be assumed
to be 1.0. I'm not convinced it is necessary as content authors who want
to be very explicit will probably set the pixelratio manually. Still, it
is trivial to expose and might make life easier for those who want this
information for low-level control of the video element size via the DOM.

Philip Jägenstedt
Opera Software

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