Wikipedia
Libvpx
libvpx is a free software video codec library from Google and the Alliance for Open Media (AOMedia). It is the reference software implementation of the video coding formats VP8, VP9, and AV1.
As free software it is published also in source code under the terms of the revised BSD license. It ships with the commandline tools vpxenc/aomenc and vpxdec/aomdec that build on its functionality.