Internal Program Version: libXv  1.0.12

The X Video Extension (Xv) extension provides support for video
adaptors attached to an X display. It takes the approach that a
display may have one or more video adaptors, each of which has one or
more ports through which independent video streams pass.

Its use is to rescale video playback, do colorspace conversions, and
change contrast, brightness and hue using video controller hardware
acceleration.

http://xorg.freedesktop.org