Some GStreamer elements may produce buffers with very non
standard strides, offsets and/or even transport each plane
in different, non-contiguous pointers. This non-standard
layout is communicated via GstVideoMeta structures attached
to the buffers. Given this, when a GstVideoMeta is available,
one should parse the layout from it instead of generating
a generic one from the caps.
The GstVideoFrame utility does precisely this: if the buffer
contains a video meta, it uses that to fill the format and
memory layout. If there is no meta available, the layout is
inferred from the caps.
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