TechSpot - PC Technology News and Analysis

x264 is a free library for encoding H.264/MPEG-4 AVC video streams.

To decode use a recent build of FFDShow or a player that supports H.264 internally - like MPlayer (there are few interesting frontends for Windows: MPlayerUI, MPlayer Frontend) and VLC (VideoLAN Client).

• x264 Full package come with an installer and contains both VFW and CLI with MeGUI.
- Microsoft .NET Framework 2.0, AVISynth and DGIndex are required to use MeGUI but NOT included.

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

Advanced settings :

- Enabling Cabac: approximately 10% bitrate reduction without loss in quality, but is slow.
- Enabling De-blocking Filter: smooths out visible blocks during an encode (rather than by using post processing to smooth out blocks while decoding). Is a good idea to enable for low bitrate encodes.

x264 limitations :

- "x264 doesn't support the error-resilience features of baseline and extended profile, not the alternative colorspaces of high profile. Properly dealing with adaptive interlacing in all cases takes lots of code. x264 doesn't support interlacing.
There are a few other features not supported..."

What's New:

- Prevent VBV from lowering quantizer too much
* This code seemed to act up unexpectedly sometimes, creating a situation where in 1-pass VBV mode, a frame's quantizer would drop all the way to qpmin and then shoot back upwards to qpmax, causing serious visual issues.
* This change may decrease bitrate in VBV mode, but that is preferable to the artifacting produced by this code.
- Improve subme7 at low QPs and add subme7 support in lossless mode