Generate proper tkhd.width and tkhd.height with non-square pixels

[kqyang]

From the spec (ISO/IEC 14496-12:2012(E)):

• For the size in tkhd (Track Header box):

width and height specify the track's visual presentation size as fixed-point 16.16 values. These need not be the same as the pixel dimensions of the images, which is documented in the sample description(s); all images in the sequence are scaled to this size, before any overall transformation of the track represented by the matrix. The pixel dimensions of the images are the default values.

So the width/height in tkhd box should be display dimension, rather than coded dimension in pixels.

We should also consider generating PixelAspectRatio box for non-square pixels.

The pixel aspect ratio and clean aperture of the video may be specified using the ‘pasp’ and ‘clap’ sample entry boxes, respectively. These are both optional; if present, they over-ride the declarations (if any) in structures specific to the video codec, which structures should be examined if these boxes are absent. For maximum compatibility, these boxes should follow, not precede, any boxes defined in or required by derived specifications.

[kqyang]

Fixed in e5b6096