x264 is a free library for encoding H264/AVC video streams.
The code is written from scratch by Laurent Aimar, Loren Merritt,
Eric Petit (OS X), Min Chen (vfw/asm), Justin Clay (vfw), Mans
Rullgard, Radek Czyz, Christian Heine (asm), Alex Izvorski, and
Alex Wright. It is released under the terms of the GPL license.
