JNT_COMP: Simplify logic on inter-inter comp modes

This patch simplies the checking criteria for the two groups of
compound modes. It also makes the encoder side cdf update inside the
RD loop consistent with that in the bitstream.

Experimental results on Google test sets (30 frames of lowres and
midres) confirm this patch obtains identical coding performance.

Change-Id: I170eea91f7d2be2170df544cfc2c692b09aa82d6

av1/decoder/decodemv.c

@@ -2196,23 +2196,21 @@ static void read_inter_block_mode_info(AV1Decoder *const pbi,
 
 #if CONFIG_JNT_COMP
   // init
-  mbmi->comp_group_idx = 1;
+  mbmi->comp_group_idx = 0;
   mbmi->compound_idx = 1;
   mbmi->interinter_compound_type = COMPOUND_AVERAGE;
 
-  // read idx to indicate current compound inter prediction mode group
-  int masked_compound_used = is_any_masked_compound_used(bsize);
-  masked_compound_used = masked_compound_used && cm->allow_masked_compound;
-
   if (has_second_ref(mbmi)) {
+    // Read idx to indicate current compound inter prediction mode group
+    const int masked_compound_used =
+        is_any_masked_compound_used(bsize) && cm->allow_masked_compound;
+
     if (masked_compound_used) {
       const int ctx_comp_group_idx = get_comp_group_idx_context(xd);
       mbmi->comp_group_idx = aom_read_symbol(
           r, ec_ctx->comp_group_idx_cdf[ctx_comp_group_idx], 2, ACCT_STR);
       if (xd->counts)
         ++xd->counts->comp_group_idx[ctx_comp_group_idx][mbmi->comp_group_idx];
-    } else {
-      mbmi->comp_group_idx = 0;
     }
 
     if (mbmi->comp_group_idx == 0) {
@@ -2222,44 +2220,33 @@ static void read_inter_block_mode_info(AV1Decoder *const pbi,
 
       if (xd->counts)
         ++xd->counts->compound_index[comp_index_ctx][mbmi->compound_idx];
-
-      if (mbmi->compound_idx) mbmi->interinter_compound_type = COMPOUND_AVERAGE;
     } else {
+      assert(cm->reference_mode != SINGLE_REFERENCE &&
+             is_inter_compound_mode(mbmi->mode) &&
+             mbmi->motion_mode == SIMPLE_TRANSLATION);
+      assert(masked_compound_used);
+
       // compound_segment, wedge
-      mbmi->interinter_compound_type = COMPOUND_AVERAGE;
-      if (cm->reference_mode != SINGLE_REFERENCE &&
-          is_inter_compound_mode(mbmi->mode) &&
-          mbmi->motion_mode == SIMPLE_TRANSLATION
-#if CONFIG_EXT_SKIP
-          && !mbmi->skip_mode
-#endif  // CONFIG_EXT_SKIP
-          ) {
-        if (is_any_masked_compound_used(bsize)) {
-          if (cm->allow_masked_compound) {
-            if (is_interinter_compound_used(COMPOUND_WEDGE, bsize))
-              mbmi->interinter_compound_type =
-                  1 + aom_read_symbol(r, ec_ctx->compound_type_cdf[bsize],
-                                      COMPOUND_TYPES - 1, ACCT_STR);
-            else
-              mbmi->interinter_compound_type = COMPOUND_SEG;
-
-            if (mbmi->interinter_compound_type == COMPOUND_WEDGE) {
-              assert(is_interinter_compound_used(COMPOUND_WEDGE, bsize));
-              mbmi->wedge_index =
-                  aom_read_literal(r, get_wedge_bits_lookup(bsize), ACCT_STR);
-              mbmi->wedge_sign = aom_read_bit(r, ACCT_STR);
-            }
-            if (mbmi->interinter_compound_type == COMPOUND_SEG) {
-              mbmi->mask_type =
-                  aom_read_literal(r, MAX_SEG_MASK_BITS, ACCT_STR);
-            }
-          }
-        }
+      if (is_interinter_compound_used(COMPOUND_WEDGE, bsize))
+        mbmi->interinter_compound_type =
+            1 + aom_read_symbol(r, ec_ctx->compound_type_cdf[bsize],
+                                COMPOUND_TYPES - 1, ACCT_STR);
+      else
+        mbmi->interinter_compound_type = COMPOUND_SEG;
 
-        if (xd->counts)
-          xd->counts->compound_interinter[bsize]
-                                         [mbmi->interinter_compound_type - 1]++;
+      if (mbmi->interinter_compound_type == COMPOUND_WEDGE) {
+        assert(is_interinter_compound_used(COMPOUND_WEDGE, bsize));
+        mbmi->wedge_index =
+            aom_read_literal(r, get_wedge_bits_lookup(bsize), ACCT_STR);
+        mbmi->wedge_sign = aom_read_bit(r, ACCT_STR);
+      } else {
+        assert(mbmi->interinter_compound_type == COMPOUND_SEG);
+        mbmi->mask_type = aom_read_literal(r, MAX_SEG_MASK_BITS, ACCT_STR);
       }
+
+      if (xd->counts)
+        xd->counts
+            ->compound_interinter[bsize][mbmi->interinter_compound_type - 1]++;
     }
   }
 #else  // CONFIG_JNT_COMP

av1/encoder/bitstream.c

@@ -1460,16 +1460,16 @@ static void pack_inter_mode_mvs(AV1_COMP *cpi, const int mi_row,
     // First write idx to indicate current compound inter prediction mode group
     // Group A (0): jnt_comp, compound_average
     // Group B (1): interintra, compound_segment, wedge
-    int masked_compound_used = is_any_masked_compound_used(bsize);
-    masked_compound_used = masked_compound_used && cm->allow_masked_compound;
-
     if (has_second_ref(mbmi)) {
-      if (masked_compound_used) {
-        assert(mbmi->comp_group_idx == 0);
+      const int masked_compound_used =
+          is_any_masked_compound_used(bsize) && cm->allow_masked_compound;
 
+      if (masked_compound_used) {
         const int ctx_comp_group_idx = get_comp_group_idx_context(xd);
         aom_write_symbol(w, mbmi->comp_group_idx,
                          ec_ctx->comp_group_idx_cdf[ctx_comp_group_idx], 2);
+      } else {
+        assert(mbmi->comp_group_idx == 0);
       }
 
       if (mbmi->comp_group_idx == 0) {
@@ -1480,27 +1480,26 @@ static void pack_inter_mode_mvs(AV1_COMP *cpi, const int mi_row,
         aom_write_symbol(w, mbmi->compound_idx,
                          ec_ctx->compound_index_cdf[comp_index_ctx], 2);
       } else {
+        assert(cpi->common.reference_mode != SINGLE_REFERENCE &&
+               is_inter_compound_mode(mbmi->mode) &&
+               mbmi->motion_mode == SIMPLE_TRANSLATION);
+        assert(masked_compound_used);
+        // compound_segment, wedge
         assert(mbmi->interinter_compound_type == COMPOUND_WEDGE ||
                mbmi->interinter_compound_type == COMPOUND_SEG);
-        // compound_segment, wedge
-        if (cpi->common.reference_mode != SINGLE_REFERENCE &&
-            is_inter_compound_mode(mbmi->mode) &&
-            mbmi->motion_mode == SIMPLE_TRANSLATION &&
-            is_any_masked_compound_used(bsize) && cm->allow_masked_compound) {
-          if (is_interinter_compound_used(COMPOUND_WEDGE, bsize))
-            aom_write_symbol(w, mbmi->interinter_compound_type - 1,
-                             ec_ctx->compound_type_cdf[bsize],
-                             COMPOUND_TYPES - 1);
-
-          if (is_interinter_compound_used(COMPOUND_WEDGE, bsize) &&
-              mbmi->interinter_compound_type == COMPOUND_WEDGE) {
-            aom_write_literal(w, mbmi->wedge_index,
-                              get_wedge_bits_lookup(bsize));
-            aom_write_bit(w, mbmi->wedge_sign);
-          }
-          if (mbmi->interinter_compound_type == COMPOUND_SEG) {
-            aom_write_literal(w, mbmi->mask_type, MAX_SEG_MASK_BITS);
-          }
+
+        if (is_interinter_compound_used(COMPOUND_WEDGE, bsize))
+          aom_write_symbol(w, mbmi->interinter_compound_type - 1,
+                           ec_ctx->compound_type_cdf[bsize],
+                           COMPOUND_TYPES - 1);
+
+        if (mbmi->interinter_compound_type == COMPOUND_WEDGE) {
+          assert(is_interinter_compound_used(COMPOUND_WEDGE, bsize));
+          aom_write_literal(w, mbmi->wedge_index, get_wedge_bits_lookup(bsize));
+          aom_write_bit(w, mbmi->wedge_sign);
+        } else {
+          assert(mbmi->interinter_compound_type == COMPOUND_SEG);
+          aom_write_literal(w, mbmi->mask_type, MAX_SEG_MASK_BITS);
         }
       }
     }

av1/encoder/encodeframe.c

@@ -1125,7 +1125,7 @@ static void update_stats(const AV1_COMMON *const cm, TileDataEnc *tile_data,
           else
             // This flag is also updated for 4x4 blocks
             rdc->single_ref_used_flag = 1;
-          if (is_comp_ref_allowed(mbmi->sb_type)) {
+          if (is_comp_ref_allowed(bsize)) {
             counts->comp_inter[av1_get_reference_mode_context(cm, xd)]
                               [has_second_ref(mbmi)]++;
             if (allow_update_cdf)
@@ -1237,31 +1237,39 @@ static void update_stats(const AV1_COMMON *const cm, TileDataEnc *tile_data,
               if (mbmi->mode == NEARESTMV) wm_ctx = 2;
             }
 
-            counts->motion_mode[wm_ctx][mbmi->sb_type][mbmi->motion_mode]++;
+            counts->motion_mode[wm_ctx][bsize][mbmi->motion_mode]++;
             if (allow_update_cdf)
-              update_cdf(fc->motion_mode_cdf[wm_ctx][mbmi->sb_type],
-                         mbmi->motion_mode, MOTION_MODES);
+              update_cdf(fc->motion_mode_cdf[wm_ctx][bsize], mbmi->motion_mode,
+                         MOTION_MODES);
 #else
-            counts->motion_mode[mbmi->sb_type][mbmi->motion_mode]++;
+            counts->motion_mode[bsize][mbmi->motion_mode]++;
             if (allow_update_cdf)
-              update_cdf(fc->motion_mode_cdf[mbmi->sb_type], mbmi->motion_mode,
+              update_cdf(fc->motion_mode_cdf[bsize], mbmi->motion_mode,
                          MOTION_MODES);
 #endif  // CONFIG_EXT_WARPED_MOTION
           } else if (motion_allowed == OBMC_CAUSAL) {
-            counts->obmc[mbmi->sb_type][mbmi->motion_mode == OBMC_CAUSAL]++;
+            counts->obmc[bsize][mbmi->motion_mode == OBMC_CAUSAL]++;
             if (allow_update_cdf)
-              update_cdf(fc->obmc_cdf[mbmi->sb_type],
-                         mbmi->motion_mode == OBMC_CAUSAL, 2);
+              update_cdf(fc->obmc_cdf[bsize], mbmi->motion_mode == OBMC_CAUSAL,
+                         2);
           }
         }
 
 #if CONFIG_JNT_COMP
         if (has_second_ref(mbmi)) {
-          const int comp_group_idx_ctx = get_comp_group_idx_context(xd);
-          ++counts->comp_group_idx[comp_group_idx_ctx][mbmi->comp_group_idx];
-          if (allow_update_cdf)
-            update_cdf(fc->comp_group_idx_cdf[comp_group_idx_ctx],
-                       mbmi->comp_group_idx, 2);
+          assert(cm->reference_mode != SINGLE_REFERENCE &&
+                 is_inter_compound_mode(mbmi->mode) &&
+                 mbmi->motion_mode == SIMPLE_TRANSLATION);
+
+          const int masked_compound_used =
+              is_any_masked_compound_used(bsize) && cm->allow_masked_compound;
+          if (masked_compound_used) {
+            const int comp_group_idx_ctx = get_comp_group_idx_context(xd);
+            ++counts->comp_group_idx[comp_group_idx_ctx][mbmi->comp_group_idx];
+            if (allow_update_cdf)
+              update_cdf(fc->comp_group_idx_cdf[comp_group_idx_ctx],
+                         mbmi->comp_group_idx, 2);
+          }
 
           if (mbmi->comp_group_idx == 0) {
             const int comp_index_ctx = get_comp_index_context(cm, xd);
@@ -1269,23 +1277,19 @@ static void update_stats(const AV1_COMMON *const cm, TileDataEnc *tile_data,
             if (allow_update_cdf)
               update_cdf(fc->compound_index_cdf[comp_index_ctx],
                          mbmi->compound_idx, 2);
-          }
-        }
-
-        if (cm->reference_mode != SINGLE_REFERENCE &&
-            is_inter_compound_mode(mbmi->mode) && mbmi->comp_group_idx &&
-            mbmi->motion_mode == SIMPLE_TRANSLATION) {
-          if (is_interinter_compound_used(COMPOUND_WEDGE, bsize)) {
-            counts->compound_interinter[bsize]
-                                       [mbmi->interinter_compound_type - 1]++;
-            if (allow_update_cdf)
-              update_cdf(fc->compound_type_cdf[bsize],
-                         mbmi->interinter_compound_type - 1,
-                         COMPOUND_TYPES - 1);
+          } else {
+            assert(masked_compound_used);
+            if (is_interinter_compound_used(COMPOUND_WEDGE, bsize)) {
+              counts->compound_interinter[bsize]
+                                         [mbmi->interinter_compound_type - 1]++;
+              if (allow_update_cdf)
+                update_cdf(fc->compound_type_cdf[bsize],
+                           mbmi->interinter_compound_type - 1,
+                           COMPOUND_TYPES - 1);
+            }
           }
         }
 #else   // CONFIG_JNT_COMP
-
         if (cm->reference_mode != SINGLE_REFERENCE &&
             is_inter_compound_mode(mbmi->mode) &&
             mbmi->motion_mode == SIMPLE_TRANSLATION) {