CVPixelBuffer data layout in iOS 12.1 ARKit

bug notes: ...frame.capturedImage in iOS 12.1 started to show green lines and wrong video frame.
Fix was to take real CVPixelBufferGetBytesPerRowOfPlane instead ofCVPixelBufferGetWidth
and stretch image with UV coords  based on the difference between the two.

Both the stride (bytes of padding added to each row), as well as the
extended rows (rows of padding at the bottom or top of the buffer) are
The extended rows are what changed in iOS6; you can find out how many rows
of padding are added to the buffer using:
CVPixelBufferGetExtendedPixels(pixelBuffer, &columnsLeft, &columnsRight,
&rowsTop, &rowsBottom)
In the example you gave (Medium preset on iOS6) you should be seeingrowsBottom = 8.

The stride is effectively CVPixelBufferGetBytesPerRowOfPlane() and includes
padding (if any).
When no padding is present CVPixelBufferGetBytesPerRowOfPlane() will be
equal to CVPixelBufferGetWidth(), otherwise it'll be greater.