A free h264/avc encoder.

x264 is a free library for encoding next-generation 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 (asm), and
Alex Wright. It is released under the terms of the GPL license. This
package contains a shared library and a commandline tool for encoding
H264 streams. This library is needed for mplayer/mencoder for H264
encoding support.

Encoder features:
- CAVLC/CABAC
- Multi-references
- Intra: all macroblock types (16x16, 8x8, and 4x4 with all predictions)
- Inter P: all partitions (from 16x16 down to 4x4)
- Inter B: partitions from 16x16 down to 8x8 (including skip/direct)
- Ratecontrol: constant quantizer, single or multipass ABR, optional VBV
- Scene cut detection
- Adaptive B-frame placement
- B-frames as references / arbitrary frame order
- 8x8 and 4x4 adaptive spatial transform
- Lossless mode
- Custom quantization matrices
- Parallel encoding of multiple slices (currently disabled)

Be aware that the x264 library is still in early development stage. The
command line tool x264 can handle only raw YUV 4:2:0 streams at the
moment so please use mencoder or another tool that supports x264 library
for all other file types.