x264 is a free software library and application for encoding video streams into the H.264/MPEG-4 AVC compression format, and is released under the terms of the GNU GPL.
The latest x264 source code can always be found by anonymous git repository:
# git clone http://git.videolan.org/git/x264.git
Or grab a daily tarball.
You can browse the source on-line.
Official builds for Windows, Linux, and MacOSX are available from here.
2013 August 23 — The x264 Development Newsletter: Volume 39 is out.
2013 July 4 — The x264 Development Newsletter: Volume 38 is out.
2013 May 20 — The x264 Development Newsletter: Volume 37 is out.
2013 May 4 — The x264 Development Newsletter: Volume 36 is out.
2010 May 25 — x264 won MSU Sixth MPEG-4 AVC/H.264 Video Codecs Comparison, with ~24% better encoding than second place.
2005 December 26 — x264 won Doom9's 2005 codec shoot-out, passing Ateme by a hair.
2005 December 12 — x264 tied for 1st place (with Ateme) in the second annual MSU MPEG-4 AVC/ H.264 codecs comparison.
For support information and to ask questions, you have the following possibilities:
A mailing list (x264-devel), a forum (Doom10), and IRC (#x264@freenode and #x264dev@freenode).
Please report any bugs to the mailing list.
If it is a crash, then compile x264 with ./configure --enable-debug
and follow the ffmpeg bugreporting guidelines.
If you use x264 in another project, let us know!