x265 version 2.2 has been released. This release contains new algorithms to limit the search of optimal transform units, a new motion search method, and optimizations to the bitstream. With this release, x265 also supports POWERPC platforms, with key functions optimized by using ALTIVEC kernels.

Full documentation is available at http://x265.readthedocs.io/en/stable/.

Release Notes for 2.2
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Encoder enhancements
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1. Enhancements to TU selection algorithm with early-outs for improved speed; use –limit-tu to exercise.
2. New motion search method SEA (Successive Elimination Algorithm) supported now as –me 4
3. Bit-stream optimizations to improve fields in PPS and SPS for bit-rate savings through –[no-]opt-qp-pps, –[no-]opt-ref-list-length-pps, and –[no-]multi-pass-opt-rps.
4. Enabled using VBV constraints when encoding without WPP.
5. All param options dumped in SEI packet in bitstream when info selected.
6. x265 now supports POWERPC-based systems. Several key functions also have optimized ALTIVEC kernels.

API changes
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1. Options to disable SEI and optional-VUI messages from bitstream made more descriptive.
2. New option –scenecut-bias to enable controlling bias to mark scene-cuts via cli.
3. Support mono and mono16 color spaces for y4m input.
4. –min-cu-size of 64 no-longer supported for reasons of visual quality (was crashing earlier anyways.)
5. API for CSV now expects version string for better integration of x265 into other applications.

Bug fixes
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1. Several fixes to slice-based encoding.
2. –log2-max-poc-lsb‘s range limited according to HEVC spec.
3. Restrict MVs to within legal boundaries when encoding.