Formats ARGB32, XRGB32, ABGR32, and XBGR32 were added to V4L2 instead
of ill-defined deprecated RGB32/BGR32 pixel formats.

When pixel format is not specified explicitly FFmpeg tries formats in
order in which they are stored in the table. Therefore formats are
sorted as follows: BGR is preferred over RGB and XBGR is preferred
over ARGB, because it could give better performance by ignoring alpha
component.