tree d8672f6cec054953c609db8f4372d4a291d1a67c
parent 89a0651d24661449f569c90f3510e54464e31ea1
author Julio Barba <juliobbv@gmail.com> 1733163263 -0500
committer Wan-Teh Chang <wtc@google.com> 1733275161 +0000

Variance Boost: 3-octile subblock variance sampling

Sample subblock variance values at octiles 4, 5, and 6; then average
them in a 1:2:1 ratio to get a composite value which is then fed to
the boost formula.

This improves bit distribution within mixed-variance superblocks
(i.e. superblocks with both low-variance and high-variance subblocks).

This results in a -0.3% BD-Rate change in SSIMULACRA2 60-80 average,
-0.5% at 10 pct, and no change in SSIMULACRA2 90 (Daala's subset1).

Bug: aomedia:375221136
Change-Id: Ibe4e41cd40eb4181172f1f53751a89d00eb80373