libv4l is a collection of libraries which adds a thin abstraction layer
on top of video4linux2 devices. The purpose of this (thin) layer is to
make it easy for application writers to support a wide variety of
devices without having to write separate code for different devices in
the same class. libv4l consists of 3 different libraries:
libv4lconvert, libv4l1 and libv4l2.

libv4lconvert offers functions to convert from any (known) pixelformat
to V4l2_PIX_FMT_BGR24 or V4l2_PIX_FMT_YUV420.

libv4l1 offers the (deprecated) v4l1 API on top of v4l2 devices,
independent of the drivers for those devices supporting v4l1
compatibility (which many v4l2 drivers do not).

libv4l2 offers the v4l2 API on top of v4l2 devices, while adding for
the application transparent libv4lconvert conversion where necessary.