commit f0179c3c75e9bbd6cafe39f0c4c38ccf26efee75
author Jingning Han <jingning@google.com> Wed Feb 22 14:11:12 2017 -0800
committer Jingning Han <jingning@google.com> Thu Feb 23 04:22:36 2017 +0000
tree 6da3b7919ebf2fe9c7c18b4a2d1b96359a47ce1e
parent 30ba4b41978888e8f1f9ca25fe5a2031f6ee31f2

Fix bottom ref condition for intra prediction in cb4x4

Resolve a rare enc/dec mismatch issue triggered by the 4x4 chroma
block size in sub8x8 block coding.

To avoid using 2x2 chroma block size, it always uses the top-left
4x4 luma block coding information to predict the 4x4 chroma block.
The rest 3 4x4 luma blocks will be coded independently without
coding the collocated chroma blocks.

The compression performance gains are 1.45% for lowres set (down
from 2.4% of the original cb4x4 design).

Change-Id: Iff560fcab172ed4219434d5174c4d8dfbbb04135