commit 6c20c78f4c513a2da9865b0838345d7d75c37405
author Arild Fuldseth (arilfuld) <arilfuld@cisco.com> Thu Jun 15 09:45:02 2017 +0200
committer Arild Fuldseth <arilfuld@cisco.com> Thu Jun 15 13:15:49 2017 +0000
tree 77195a7b0184c7efede91f0defe40ff8fd015f8d
parent 29e40a65292525d443e2ad9e0d422a2ca6569075

Fix a bug in determination of reference_mode

Fix a bug where the encoder sets reference_mode =
COMPOUND_REFERENCE even if the frame contains some
4x4 blocks (but no larger blocks) that are single
reference. This occurs only in corner cases,
typically for very small frame sizes (e.g. 16x8).

BUG=aomedia:575

Change-Id: I5caedaa753a56e9f9b48995c1d2e0a0886aa4366

av1/encoder/encodeframe.c

diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 5c8744e..98913db 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -1557,6 +1557,7 @@
 #endif
   if (!frame_is_intra_only(cm)) {
     FRAME_COUNTS *const counts = td->counts;
+    RD_COUNTS *rdc = &td->rd_counts;
     const int inter_block = is_inter_block(mbmi);
     const int seg_ref_active =
         segfeature_active(&cm->seg, mbmi->segment_id, SEG_LVL_REF_FRAME);
@@ -1575,6 +1576,12 @@
 #endif  // CONFIG_EXT_REFS
 
         if (cm->reference_mode == REFERENCE_MODE_SELECT) {
+          if (has_second_ref(mbmi))
+            // This flag is also updated for 4x4 blocks
+            rdc->compound_ref_used_flag = 1;
+          else
+            // This flag is also updated for 4x4 blocks
+            rdc->single_ref_used_flag = 1;
 #if !SUB8X8_COMP_REF
           if (mbmi->sb_type != BLOCK_4X4)
             counts->comp_inter[av1_get_reference_mode_context(cm, xd)]
@@ -5089,25 +5096,23 @@
 #if CONFIG_EXT_INTER
     make_consistent_compound_tools(cm);
 #endif  // CONFIG_EXT_INTER
+
+    rdc->single_ref_used_flag = 0;
+    rdc->compound_ref_used_flag = 0;
+
     encode_frame_internal(cpi);
 
     for (i = 0; i < REFERENCE_MODES; ++i)
       mode_thrs[i] = (mode_thrs[i] + rdc->comp_pred_diff[i] / cm->MBs) / 2;
 
     if (cm->reference_mode == REFERENCE_MODE_SELECT) {
-      int single_count_zero = 0;
-      int comp_count_zero = 0;
-
-      for (i = 0; i < COMP_INTER_CONTEXTS; i++) {
-        single_count_zero += counts->comp_inter[i][0];
-        comp_count_zero += counts->comp_inter[i][1];
-      }
-
-      if (comp_count_zero == 0) {
+      // Use a flag that includes 4x4 blocks
+      if (rdc->compound_ref_used_flag == 0) {
         cm->reference_mode = SINGLE_REFERENCE;
         av1_zero(counts->comp_inter);
 #if !CONFIG_REF_ADAPT
-      } else if (single_count_zero == 0) {
+        // Use a flag that includes 4x4 blocks
+      } else if (rdc->single_ref_used_flag == 0) {
         cm->reference_mode = COMPOUND_REFERENCE;
         av1_zero(counts->comp_inter);
 #endif  // !CONFIG_REF_ADAPT