NEW_MULTISYMBOL: add CDF for segment_id prediction.

With aq-mode=1 (which forces segmentation), AWCY
gives -0.12% (objective-1-fast, cpu-used=4,
NEW_MULTISYMBOL on for reference and tested).

No change to baseline metrics, with or without
NEW_MULTISYMBOL.

Change-Id: I841a9e8978598402dacfbca9265269163f7440c0

av1/common/entropy.c

@@ -5657,6 +5657,9 @@ void av1_average_tile_intra_cdfs(FRAME_CONTEXT *fc, FRAME_CONTEXT *ec_ctxs[],
   AVERAGE_TILE_CDFS(inter_ext_tx_cdf)
 
   AVERAGE_TILE_CDFS(seg.tree_cdf)
+#if CONFIG_NEW_MULTISYMBOL
+  AVERAGE_TILE_CDFS(seg.pred_cdf)
+#endif
   AVERAGE_TILE_CDFS(uv_mode_cdf)
 
   AVERAGE_TILE_CDFS(partition_cdf)

av1/common/entropymode.c

@@ -2509,6 +2509,14 @@ static const aom_prob default_segment_tree_probs[SEG_TREE_PROBS] = {
 static const aom_prob default_segment_pred_probs[PREDICTION_PROBS] = {
   128, 128, 128
 };
+#if CONFIG_NEW_MULTISYMBOL
+static const aom_cdf_prob
+    default_segment_pred_cdf[PREDICTION_PROBS][CDF_SIZE(2)] = {
+  { AOM_ICDF(128 * 128), AOM_ICDF(32768), 0},
+  { AOM_ICDF(128 * 128), AOM_ICDF(32768), 0},
+  { AOM_ICDF(128 * 128), AOM_ICDF(32768), 0}
+};
+#endif
 // clang-format on
 
 #if CONFIG_DUAL_FILTER
@@ -4860,6 +4868,9 @@ static void init_mode_probs(FRAME_CONTEXT *fc) {
 #endif  // CONFIG_SUPERTX
   av1_copy(fc->seg.tree_probs, default_segment_tree_probs);
   av1_copy(fc->seg.pred_probs, default_segment_pred_probs);
+#if CONFIG_NEW_MULTISYMBOL
+  av1_copy(fc->seg.pred_cdf, default_segment_pred_cdf);
+#endif
 #if CONFIG_EXT_INTRA
 #if CONFIG_INTRA_INTERP
   av1_copy(fc->intra_filter_probs, default_intra_filter_probs);

av1/common/pred_common.h

@@ -54,6 +54,13 @@ static INLINE aom_prob av1_get_pred_prob_seg_id(
   return segp->pred_probs[av1_get_pred_context_seg_id(xd)];
 }
 
+#if CONFIG_NEW_MULTISYMBOL
+static INLINE aom_cdf_prob *av1_get_pred_cdf_seg_id(
+    struct segmentation_probs *segp, const MACROBLOCKD *xd) {
+  return segp->pred_cdf[av1_get_pred_context_seg_id(xd)];
+}
+#endif
+
 static INLINE int av1_get_skip_context(const MACROBLOCKD *xd) {
   const MODE_INFO *const above_mi = xd->above_mi;
   const MODE_INFO *const left_mi = xd->left_mi;

av1/common/seg_common.h

@@ -50,6 +50,9 @@ struct segmentation_probs {
   aom_prob tree_probs[SEG_TREE_PROBS];
   aom_cdf_prob tree_cdf[CDF_SIZE(MAX_SEGMENTS)];
   aom_prob pred_probs[PREDICTION_PROBS];
+#if CONFIG_NEW_MULTISYMBOL
+  aom_cdf_prob pred_cdf[PREDICTION_PROBS][CDF_SIZE(2)];
+#endif
 };
 
 static INLINE int segfeature_active(const struct segmentation *seg,

av1/decoder/decodemv.c

@@ -661,8 +661,13 @@ static int read_inter_segment_id(AV1_COMMON *const cm, MACROBLOCKD *const xd,
 
   if (seg->temporal_update) {
     const int ctx = av1_get_pred_context_seg_id(xd);
+#if CONFIG_NEW_MULTISYMBOL
+    aom_cdf_prob *pred_cdf = segp->pred_cdf[ctx];
+    mbmi->seg_id_predicted = aom_read_symbol(r, pred_cdf, 2, ACCT_STR);
+#else
     const aom_prob pred_prob = segp->pred_probs[ctx];
     mbmi->seg_id_predicted = aom_read(r, pred_prob, ACCT_STR);
+#endif
     if (counts) ++counts->seg.pred[ctx][mbmi->seg_id_predicted];
     if (mbmi->seg_id_predicted) {
       segment_id = predicted_segment_id;

av1/encoder/bitstream.c

@@ -1708,8 +1708,13 @@ static void pack_inter_mode_mvs(AV1_COMP *cpi, const int mi_row,
   if (seg->update_map) {
     if (seg->temporal_update) {
       const int pred_flag = mbmi->seg_id_predicted;
+#if CONFIG_NEW_MULTISYMBOL
+      aom_cdf_prob *pred_cdf = av1_get_pred_cdf_seg_id(segp, xd);
+      aom_write_symbol(w, pred_flag, pred_cdf, 2);
+#else
       aom_prob pred_prob = av1_get_pred_prob_seg_id(segp, xd);
       aom_write(w, pred_flag, pred_prob);
+#endif
       if (!pred_flag) write_segment_id(w, seg, segp, segment_id);
     } else {
       write_segment_id(w, seg, segp, segment_id);

av1/encoder/segmentation.c

@@ -299,7 +299,7 @@ void av1_choose_segmap_coding_method(AV1_COMMON *cm, MACROBLOCKD *xd) {
   int no_pred_cost;
   int t_pred_cost = INT_MAX;
 
-  int i, tile_col, tile_row, mi_row, mi_col;
+  int tile_col, tile_row, mi_row, mi_col;
 #if CONFIG_TILE_GROUPS
   const int probwt = cm->num_tg;
 #else
@@ -312,7 +312,9 @@ void av1_choose_segmap_coding_method(AV1_COMMON *cm, MACROBLOCKD *xd) {
 
   aom_prob no_pred_tree[SEG_TREE_PROBS];
   aom_prob t_pred_tree[SEG_TREE_PROBS];
+#if !CONFIG_NEW_MULTISYMBOL
   aom_prob t_nopred_prob[PREDICTION_PROBS];
+#endif
 
   (void)xd;
 
@@ -357,8 +359,9 @@ void av1_choose_segmap_coding_method(AV1_COMMON *cm, MACROBLOCKD *xd) {
     calc_segtree_probs(t_unpred_seg_counts, t_pred_tree, segp->tree_probs,
                        probwt);
     t_pred_cost = cost_segmap(t_unpred_seg_counts, t_pred_tree);
-
+#if !CONFIG_NEW_MULTISYMBOL
     // Add in the cost of the signaling for each prediction context.
+    int i;
     for (i = 0; i < PREDICTION_PROBS; i++) {
       const int count0 = temporal_predictor_count[i][0];
       const int count1 = temporal_predictor_count[i][1];
@@ -372,6 +375,7 @@ void av1_choose_segmap_coding_method(AV1_COMMON *cm, MACROBLOCKD *xd) {
       t_pred_cost += count0 * av1_cost_zero(t_nopred_prob[i]) +
                      count1 * av1_cost_one(t_nopred_prob[i]);
     }
+#endif
   }
 
   // Now choose which coding method to use.