x264 is a free software library for encoding video streams into the H.264/MPEG-4 AVC format. It is released under the terms of the GNU General Public License.
x264 was originally developed by Laurent Aimar, who stopped development in 2004 after being hired by ATEME, Loren Merritt then took over development. Today, x264 is primarily developed by Loren Merritt, Jason Garrett-Glaser, Steven Walters, Anton Mitrofanov, Henrik Gramner and Daniel Kang.
x264 provides a command line interface as well as an API. The former is used by many graphical user interfaces, such as Staxrip and MeGUI. The latter is used by many other interfaces, such as HandBrake and FFmpeg
As of August 2008, x264 implements more features than any other H.264 encoder.
x264 has some notable psychovisual enhancements which help to increase the visual quality.
x264 has won awards in the following codec comparisons:
x264 has SIMD assembly code acceleration on x86, PowerPC (using AltiVec), and ARMv7 (using NEON) platforms.
In April 2010, the x264 project announced full Blu-ray compliant video encoding capability making x264 the first free Blu-ray compliant software H.264 encoder. x264 has always had the ability to create video streams that are playable on most Blu-ray devices; however, it was up to the user to choose appropriate conversion settings. The default x264 preset chooses adequate compatibility for Blu-ray players; however, it is now possible to choose more complex conversion settings while simply maintaining compatibility by explicitly enabling Blu-ray compatibility mode. Blu-ray compatibility can be useful when striving for cross device compatibility (especially in the realm of high definition hardware media players).