We’re pleased to announce that x265 has reached another milestone! The v1.5 release of x265 has major improvements in Main10 compression efficiency and performance over the 1.4 release, general improvements in Main performance. Psycho-visual optimizations are now enabled by default in the presets which can support it (medium, slow, slower, veryslow and placebo).

Feature additions:

* analysis re-use features have been completed
* rate control zones have been introduced
* –tune grain introduced
* deblocking tC and Beta offsets are now configurable
* denoise is seperately configurable for inter and intra CUs
* frame based CSV logging has been improved
* New support for VTune task profiles

Presets and defaults:

ultrafast no longer disables the deblocking loop filter
psy-rd defaults to 0.3 (was 0, disabled)
psy-rdoq defaults to 1.0 (was 0, disabled)
aq-mode defaults to 1 (was 2, auto-variance)
4:2:2 and 4:4:4 encodes no longer generate compliance warnings

API changes:

param.rc.rateTolerance has been removed and replaced with a simpler param.rc.bStrictCbr flag.

--log-level debug is now --log-level 4 instead of --log-level 3. A new ‘frame’ log level was inserted at level 3 in order to support frame level CSV logging without also enabling frame level console logging. Using the string name ‘debug’ is unambiguous as its behavior has not changed.

The online documentation has all the details: http://x265.readthedocs.org/en/1.5/