x265 version 2.6 released

By Pradeep Ramachandran

New features
1) x265 can now refine analysis from a previous HEVC encode (using options –refine-inter, and –refine-intra), or a previous AVC encode (using option –refine-mv-type). The previous encode‚Äôs information can be packaged using the x265_analysis_data_t data field available in the x265_picture object.
2) Basic support for segmented (or chunked) encoding added with –vbv-end that can specify the status of CPB at the end of a segment. String this together with –vbv-init to encode a title as chunks while maintaining VBV compliance!
3) –force-flush can be used to trigger a premature flush of the encoder. This option is beneficial when input is known to be bursty, and may be at a rate slower than the encoder.
4) Experimental feature –lowpass-dct that uses truncated DCT for transformation.
Encoder enhancements
1) Slice-parallel mode gets a significant boost in performance, particularly in low-latency mode.
2) x265 now officially supported on VS2017.
3) x265 now supports all depths from mono0 to mono16 for Y4M format.
API changes
1) Options that modified PPS dynamically (–opt-qp-pps and –opt-ref-list-length-pps) are now disabled by default to enable users to save bits by not sending headers. If these options are enabled, headers have to be repeated for every GOP.
2) Rate-control and analysis parameters can dynamically be reconfigured simultaneously via the x265_encoder_reconfig API.
3) New API functions to extract intermediate information such as slice-type, scenecut information, reference frames, etc. are now available. This information may be beneficial to integrating applications that are attempting to perform content-adaptive encoding. Refer to documentation on x265_get_slicetype_poc_and_scenecut, and x265_get_ref_frame_list for more details and suggested usage.
4) A new API to pass supplemental CTU information to x265 to influence analysis decisions has been added. Refer to documentation on x265_encoder_ctu_info for more details.
Bug fixes
1) Bug fixes when –slices is used with VBV settings.
2) Minor memory leak fixed for HDR10+ builds, and default x265 when pools option is specified.
3) HDR10+ bug fix to remove dependence on poc counter to select meta-data information.