It appears the spec calculation gives the h:w pixel ratio, where-as
we want w:h. It's pretty easy to convince oneself that this way round
is correct. Consider a video that's 100px by 100px, and setting
aspectRatioCode=3 to achieve this. The pixelWidthHeightRatio needs to
be 16/9 and not 9/16 :).
Issue: #965
