x265

x265 is a free and open source encoding library and application for encoding HEVC/H.265 video files.

Features:

• Provides next-generation compression and codec.
• Fast and excellent quality.
• Completly free and libre software, ensuring freedom for everyone.
• The APIs are similar to x264 APIs

Encoder features

• Full prediction and transform quad-tree recursion supported
• Adaptive B-frame placement
• B-frames as references / arbitrary frame order
• CABAC entropy coding
• Intra: all block types (32x32, 16x16, 8x8, 4x4, and PCM with all predictions)
• Inter P: all partitions (from 64x64 down to 8x4)
• Inter B: partitions from 64x64 down to 8x4 (including all merge modes
and biprediction)
• Weighted prediction for P slices
• Multiple reference frames
• Ratecontrol: constant quantizer, constant quality, single pass ABR, optional VBV
• Scenecut detection
• Parallel encoding on multiple CPUs, both frame-level and wavefront parallelism

• Release Date: Sep 27, 2019
• New features
  • 3-level hierarchical motion estimation using --hme and --hme-search.
  • New AQ mode (--aq-mode 4) with variance and edge information.
  • selective-sao to selectively enable SAO at slice level.
  • Enhancements to existing features
  • New implementation of --refine-mv with 3 refinement levels.
  • Encoder enhancements
  • Improved quality in the frames following dark scenes in ABR mode.
  • API changes
  • Additions to x265_param structure to support the newly added features --hme, --hme-search and selective-sao.
  Bug fixes
  • Fixed encoder crash with --zonefile during failures in encoder_open().
  • Fixed JSON11 build errors with HDR10+ on MacOS high sierra.
  • Signalling out of range scaling list data fixed.
  • Inconsistent output fix for 2-pass rate-control with cutree ON.
  Known issues
  • Build dependency on changeset cf37911 of SVT-HEVC.