libaom v3.2.0 Released

[Wan-Teh Chang]

Hello everyone,

libaom v3.2.0 has been released. The source code of the release can be
checked out from the git repository[1] using the release tag v3.2.0.
Alternatively, the release tarball[2], along with the signature file[3],
can be downloaded.

Thanks.

[1] https://aomedia.googlesource.com/aom
[2] https://storage.googleapis.com/aom-releases/libaom-3.2.0.tar.gz
[3] https://storage.googleapis.com/aom-releases/libaom-3.2.0.tar.gz.asc

This release includes compression efficiency and perceptual quality
improvements, speedup and memory optimizations, as well as some new
features.

- New Features
* Introduced speeds 7, 8, and 9 for all intra mode.
* Introduced speed 10 for real time mode.
* Introduced an API that allows external partition decisions.
NOTE: The external partition API should be considered experimental.
Until the external partition API is declared stable, breaking
changes may be made to this API in a future libaom release.
* SVC: added support for compound prediction.
* SVC: added support for fixed SVC modes.

- Compression Efficiency Improvements
* Intra-mode search improvement.
* Improved real time (RT) mode BDrate savings by ~5% (RT speed 5)
and ~12% (RT speed 6). The improvement was measured on the video
conference set.
* Improved real time mode for nonrd path (speed 7, 8, 9): BDrate
gains of ~3-5%.
* Rate control and RD adjustments based on ML research in VP9.
Gains of ~0.5-1.0% for HD.

- Perceptual Quality Improvements
* Added a new mode --deltaq-mode=3 to improve perceptual quality
based on a differential contrast model for still images.
* Added a new mode –deltaq-mode=4 to improve perceptual quality
based on user rated cq_level data set for still images.
* Weighting of some intra mode and partition size choices to better
manage and retain texture.

- Speedup and Memory Optimizations
* Further improved 2-pass good quality encoder speed:
o Speed 2 speedup: 18%
o Speed 3 speedup: 22%
o Speed 4 speedup: 37%
o Speed 5 speedup: 30%
o Speed 6 speedup: 20%
* Optimized the real time encoder (measured on the video conference
set):
o RT speed 5 speedup: 110%
o RT speed 6 speedup: 77%

- Bug Fixes
* Issue 3069: Fix one-pass mode keyframe placement off-by-one error.
* Issue 3156: Fix a bug in av1_quantize_lp AVX2 optimization.