commit a1e7dfea12e9f5553b97320a2f569e6e69fa5eac
author Jingning Han <jingning@google.com> Fri Jan 03 15:36:27 2020 -0800
committer Jingning Han <jingning@google.com> Tue Jan 07 22:13:24 2020 +0000
tree fae4dd1976bf2022e513b28986fa53f862702683
parent 734035f8897c789e37a30aa36b2e180803a73ca0

Forward step motion search

Allow forward step motion search at highest search scale. This
improves the motion search quality. In speed 1, the coding performance
of vbr mode at 150 frames changes:

      avg PSNR     overall PSNR     SSIM
low   -0.051	    -0.048	   -0.032
mid   -0.091	    -0.079	   -0.100
hd    -0.117	    -0.175	   -0.149

Most clips remain neutral, several gain between 1 - 4% in PSNR.

STATS_CHANGED

Change-Id: Ia197d5394c4847436d05925639676c3d01a0c3b1

av1/encoder/mcomp.c

diff --git a/av1/encoder/mcomp.c b/av1/encoder/mcomp.c
index e95041a..0eabacb 100644
--- a/av1/encoder/mcomp.c
+++ b/av1/encoder/mcomp.c
@@ -183,10 +183,11 @@
   int stage_index = 0;
   cfg->stride = stride;
   int radius = 1;
-  for (stage_index = 0; stage_index < 12; ++stage_index) {
+  for (stage_index = 0; stage_index < 15; ++stage_index) {
     int tan_radius = AOMMAX((int)(0.41 * radius), 1);
     int num_search_pts = 12;
     if (radius == 1) num_search_pts = 8;
+
     const MV ss_mvs[13] = {
       { 0, 0 },
       { -radius, 0 },
@@ -211,7 +212,8 @@
     cfg->searches_per_step[stage_index] = num_search_pts;
     cfg->radius[stage_index] = radius;
     ++ss_count;
-    radius = (int)AOMMAX((radius * 1.5 + 0.5), radius + 1);
+    if (stage_index < 12)
+      radius = (int)AOMMAX((radius * 1.5 + 0.5), radius + 1);
   }
   cfg->ss_count = ss_count;
 }
@@ -1792,9 +1794,11 @@
 
   bestsad += mvsad_err_cost(x, best_mv, &fcenter_mv, sad_per_bit);
 
+  int next_step_size = tot_steps > 2 ? cfg->radius[tot_steps - 2] : 1;
   for (int step = tot_steps - 1; step >= 0; --step) {
     const search_site *ss = cfg->ss[step];
     best_site = 0;
+    if (step > 0) next_step_size = cfg->radius[step - 1];
 
     int all_in = 1, j;
     // Trap illegal vectors
@@ -1866,6 +1870,14 @@
     }
 
     if (is_off_center == 0) (*num00)++;
+
+    if (best_site == 0) {
+      while (next_step_size == cfg->radius[step] && step > 2) {
+        ++(*num00);
+        --step;
+        next_step_size = cfg->radius[step - 1];
+      }
+    }
   }
 
   return bestsad;