Version 2.3
===========

Encoder enhancements
--------------------
1. New SSIM-based RD-cost computation for improved visual quality, and efficiency; use :option:`--ssim-rd` to exercise.
2. Multi-pass encoding can now share analysis information from prior passes (in addition to rate-control information) to improve performance and quality of subsequent passes; to your multi-pass command-lines that use the :option:`--pass` option, add :option:`--multi-pass-opt-distortion` to share distortion information, and :option:`--multi-pass-opt-analysis` to share other analysis information.
3. A dedicated thread pool for lookahead can now be specified with :option:`--lookahead-threads`.
4. option:`--dynamic-rd` dynamically increase analysis in areas where the bitrate is being capped by VBV; works for both CRF and ABR encodes with VBV settings.
5. The number of bits used to signal the delta-QP can be optimized with the :option:`--opt-cu-delta-qp` option; found to be useful in some scenarios for lower bitrate targets.
6. Experimental feature option:`--aq-motion` adds new QP offsets based on relative motion of a block with respect to the movement of the frame.

API changes
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1. Reconfigure API now supports signalling new scaling lists.
2. x265 application's csv functionality now reports time (in milliseconds) taken to encode each frame.
3. :option:`--strict-cbr` enables stricter bitrate adherence by adding filler bits when achieved bitrate is lower than the target; earlier, it was only reacting when the achieved rate was higher.
4. :option:`--hdr` can be used to ensure that max-cll and max-fall values are always signaled (even if 0,0).

Bug fixes
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1. Fixed incorrect HW thread counting on MacOS platform.
2. Fixed scaling lists support for 4:4:4 videos.
3. Inconsistent output fix for :option:`--opt-qp-pss` by removing last slice's QP from cost calculation.
4. VTune profiling (enabled using ENABLE_VTUNE CMake option) now also works with 2017 VTune builds.


(adam)