tree a7cb0018327ddd30113dac7c87286be076182ce9
parent 39edc6a5c1555a4683693ad91cf00f7c1da55359
author Debargha Mukherjee <debargha@google.com> 1552934998 -0700
committer Debargha Mukherjee <debargha@google.com> 1553180328 +0000

Add an optimization for intra tx size search

When all three transform size levels are searched for intra, prune
the smallest size search if the second level is already less efficient
than the largest size for low contrast blocks.

Gives slight speedup of 0.25% by instruction count with negligible
stats difference. More importantly it enables us to upgrade to full
depth txfm search in various speed settings without much loss.

Stats on 20 frames --end-usage=q mode:
midres: -0.01%
lowres: +0.02%

STATS_CHANGED

Change-Id: I972a9d4f120d6df79532ef26556cff698034ef71