commit bb369bd95e5d187985241a633c2d9f7d4b16dbad
author Marco Paniconi <marpan@google.com> Fri Nov 20 12:19:13 2020 -0800
committer Marco Paniconi <marpan@google.com> Fri Nov 20 16:09:05 2020 -0800
tree 96df72ab8e4c4f0c6d3578805c1ed2baf42cb97a
parent c77c8fbdf27e8b4326283de0188be1267325bab7

rtc: Reduce threshold[0] in var part for sp 9 high resoln

For speed 9 (where force_large_partition_blocks is on) and
resolutions above 480p: the current threshold[0] (to split 128x128)
can become equal to or larger than the threshold[1] (to split 64x64),
which should not happen.

This change makes sure threshold[0] stays smaller than threshold[1].

Speed differene on a few 720p clips is small (within ~1-2%), but
bdrate on 720p clips have good gains (from ~1-5%).
avg bdrate gain ~0.9 on rtc_set.

Change-Id: I1bb155b96478c520b71199a48694830d0171370b

av1/encoder/var_based_part.c

diff --git a/av1/encoder/var_based_part.c b/av1/encoder/var_based_part.c
index aada04d..c6d0f05 100644
--- a/av1/encoder/var_based_part.c
+++ b/av1/encoder/var_based_part.c
@@ -424,7 +424,7 @@
         thresholds[2] <<= 5;
         thresholds[3] = INT32_MAX;
       } else if (cm->width * cm->height > 640 * 480 && segment_id == 0) {
-        thresholds[0] <<= 2;
+        thresholds[0] = (3 * thresholds[0]) >> 1;
         thresholds[3] = INT32_MAX;
         if (current_qindex >= QINDEX_LARGE_BLOCK_THR) {
           thresholds[1] <<= 1;