tree ad6d27672f3ad2c4554a65493477680cfbaa4bc9
parent c9ebc2a2b90683e4635336a092efa4c5de19580b
author Cheng Chen <chengchen@google.com> 1619505964 -0700
committer Cheng Chen <chengchen@google.com> 1619627509 +0000

Do not terminate palette mode search using rd estimation

Function "model_intra_yrd_and_prune()" was redesigned in CL:
https://aomedia-review.googlesource.com/c/aom/+/130501,
which skips an intra mode search when its estimated rd cost is
1.25 times larger than the current best rd cost.

It causes function "av1_determine_sc_tools_with_encoding()"
fail to identify screen content videos. A quality regression is
seen on screen content videos.

The reason is that palette mode is significantly different to
traditional intra modes. The pruning might not work well for it.

Removing this early termination in palette mode allows the function
"av1_determine_sc_tools_with_encoding()" to effectively detect
whether to use screen content tools.

For example, clip "chinaspeed_xga" now uses screen content tools
after this change.

As compared to the current head, on speed 4, screen content set,
the coding performance is improved by
-1.67% (ovr_psnr), -1.49% (ssim).

STATS_CHANGED

Change-Id: Iad8d15029c3db3c0c5e72ec0bd46be7df0fab932