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Adjustment on limiting cyclic refresh on steady blocks.

Adjust the qp threshold and consec_zeromv threshold for
limiting cyclic refresh. Also increase the refresh period
when the limit amount is significant, and some code-cleanup.

Small gain in PSNR/SSIM metrics: ~0.25/0.3 gain on RTC set, speed 7.

Change only affects non-screen content.

Change-Id: I1ced87a89a132684c071e722616e445b2d18236a

--- a/vp9/encoder/vp9_aq_cyclicrefresh.c

+++ b/vp9/encoder/vp9_aq_cyclicrefresh.c

@@ -167,7 +167,8 @@

   int num8x8bl = cm->MBs << 2;

   // Weight for segment prior to encoding: take the average of the target

   // number for the frame to be encoded and the actual from the previous frame.

-  double weight_segment = (double)((cr->target_num_seg_blocks +

+  int target_refresh = cr->percent_refresh * cm->mi_rows * cm->mi_cols / 100;

+  double weight_segment = (double)((target_refresh +

       cr->actual_num_seg1_blocks + cr->actual_num_seg2_blocks) >> 1) /

       num8x8bl;

   // Compute delta-q corresponding to qindex i.

@@ -208,7 +209,7 @@

   // segment_id.

   if (cyclic_refresh_segment_id_boosted(mbmi->segment_id)) {

     mbmi->segment_id = refresh_this_block;

-    // Reset segment_id if will be skipped.

+    // Reset segment_id if it will be skipped.

     if (skip)

       mbmi->segment_id = CR_SEGMENT_ID_BASE;

   }

@@ -396,6 +397,9 @@

   int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame;

   int xmis, ymis, x, y;

   int consec_zero_mv_thresh = 0;

+  int qindex_thresh = 0;

+  int count_sel = 0;

+  int count_tot = 0;

   memset(seg_map, CR_SEGMENT_ID_BASE, cm->mi_rows * cm->mi_cols);

   sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;

   sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;

@@ -408,9 +412,12 @@

   assert(cr->sb_index < sbs_in_frame);

   i = cr->sb_index;

   cr->target_num_seg_blocks = 0;

-  if (cpi->oxcf.content != VP9E_CONTENT_SCREEN &&

-      cr->percent_refresh > 0)

-    consec_zero_mv_thresh = 10 * (100 / cr->percent_refresh);

+  if (cpi->oxcf.content != VP9E_CONTENT_SCREEN)

+    consec_zero_mv_thresh = 100;

+  qindex_thresh =

+      cpi->oxcf.content == VP9E_CONTENT_SCREEN

+      ? vp9_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST2, cm->base_qindex)

+      : vp9_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST1, cm->base_qindex);

   do {

     int sum_map = 0;

     // Get the mi_row/mi_col corresponding to superblock index i.

@@ -418,8 +425,6 @@

     int sb_col_index = i - sb_row_index * sb_cols;

     int mi_row = sb_row_index * MI_BLOCK_SIZE;

     int mi_col = sb_col_index * MI_BLOCK_SIZE;

-    int qindex_thresh =

-        vp9_get_qindex(&cm->seg, CR_SEGMENT_ID_BOOST2, cm->base_qindex);

     assert(mi_row >= 0 && mi_row < cm->mi_rows);

     assert(mi_col >= 0 && mi_col < cm->mi_cols);

     bl_index = mi_row * cm->mi_cols + mi_col;

@@ -435,9 +440,12 @@

         // for possible boost/refresh (segment 1). The segment id may get

         // reset to 0 later if block gets coded anything other than ZEROMV.

         if (cr->map[bl_index2] == 0) {

+          count_tot++;

           if (cr->last_coded_q_map[bl_index2] > qindex_thresh ||

-              cr->consec_zero_mv[bl_index2] < consec_zero_mv_thresh)

+              cr->consec_zero_mv[bl_index2] < consec_zero_mv_thresh) {

             sum_map++;

+            count_sel++;

+          }

         } else if (cr->map[bl_index2] < 0) {

           cr->map[bl_index2]++;

         }

@@ -458,6 +466,9 @@

     }

   } while (cr->target_num_seg_blocks < block_count && i != cr->sb_index);

   cr->sb_index = i;

+  cr->reduce_refresh = 0;

+  if (count_sel < (3 * count_tot) >> 2)

+    cr->reduce_refresh = 1;

 }

 // Set cyclic refresh parameters.

@@ -466,6 +477,8 @@

   const VP9_COMMON *const cm = &cpi->common;

   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;

   cr->percent_refresh = 10;

+  if (cr->reduce_refresh)

+    cr->percent_refresh = 5;

   cr->max_qdelta_perc = 50;

   cr->time_for_refresh = 0;

   // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4)

--- a/vp9/encoder/vp9_aq_cyclicrefresh.h

+++ b/vp9/encoder/vp9_aq_cyclicrefresh.h

@@ -66,6 +66,7 @@

   int rate_boost_fac;

   double low_content_avg;

   int qindex_delta[3];

+  int reduce_refresh;

 };

 struct VP9_COMP;