Some refactoring/cleanup of global motion costing

Change-Id: Ib44c713ebcccc621d4f3b9f22e8dbb638c50ff52

av1/common/mv.h

@@ -128,6 +128,13 @@ typedef struct {
 #define GM_ALPHA_MIN -GM_ALPHA_MAX
 #define GM_ROW3HOMO_MIN -GM_ROW3HOMO_MAX
 
+// Bits used for different models
+#define GM_IDENTITY_BITS 0
+#define GM_TRANSLATION_BITS ((GM_ABS_TRANS_BITS + 1) * 2)
+#define GM_ROTZOOM_BITS (GM_TRANSLATION_BITS + (GM_ABS_ALPHA_BITS + 1) * 2)
+#define GM_AFFINE_BITS (GM_ROTZOOM_BITS + (GM_ABS_ALPHA_BITS + 1) * 2)
+#define GM_HOMOGRAPHY_BITS (GM_AFFINE_BITS + (GM_ABS_ROW3HOMO_BITS + 1) * 2)
+
 // Convert a global motion translation vector (which may have more bits than a
 // regular motion vector) into a motion vector
 static INLINE int_mv gm_get_motion_vector(const WarpedMotionParams *gm,

av1/encoder/encoder.h

@@ -570,6 +570,9 @@ typedef struct AV1_COMP {
 #if CONFIG_LOOP_RESTORATION
   int switchable_restore_cost[RESTORE_SWITCHABLE_TYPES];
 #endif  // CONFIG_LOOP_RESTORATION
+#if CONFIG_GLOBAL_MOTION
+  int gmtype_cost[TRANS_TYPES];
+#endif  // CONFIG_GLOBAL_MOTION
 
   int multi_arf_allowed;
   int multi_arf_enabled;

av1/encoder/rd.c

@@ -156,6 +156,10 @@ static void fill_mode_costs(AV1_COMP *cpi) {
   av1_cost_tokens(cpi->switchable_restore_cost, fc->switchable_restore_prob,
                   av1_switchable_restore_tree);
 #endif  // CONFIG_LOOP_RESTORATION
+#if CONFIG_GLOBAL_MOTION
+  av1_cost_tokens(cpi->gmtype_cost, fc->global_motion_types_prob,
+                  av1_global_motion_types_tree);
+#endif  // CONFIG_GLOBAL_MOTION
 }
 
 void av1_fill_token_costs(av1_coeff_cost *c,

av1/encoder/rdopt.c

@@ -4336,35 +4336,22 @@ static int get_interinter_compound_type_bits(BLOCK_SIZE bsize,
 #define GLOBAL_MOTION_COST_AMORTIZATION_BLKS 8
 
 #if GLOBAL_MOTION_COST_AMORTIZATION_BLKS > 0
-static int get_gmbitcost(const WarpedMotionParams *gm, const aom_prob *probs) {
-  int gmtype_cost[TRANS_TYPES];
-  int bits;
-  TransformationType type = gm->wmtype;
-  av1_cost_tokens(gmtype_cost, probs, av1_global_motion_types_tree);
-  switch (type) {
-    case HOMOGRAPHY:
-      bits = (GM_ABS_TRANS_BITS + 1) * 2 + (GM_ABS_ALPHA_BITS + 1) * 4 +
-             (GM_ABS_ROW3HOMO_BITS + 1) * 2;
-      break;
-    case AFFINE:
-      bits = (GM_ABS_TRANS_BITS + 1) * 2 + (GM_ABS_ALPHA_BITS + 1) * 4;
-      break;
-    case ROTZOOM:
-      bits = (GM_ABS_TRANS_BITS + 1) * 2 + (GM_ABS_ALPHA_BITS + 1) * 2;
-      break;
-    case TRANSLATION: bits = (GM_ABS_TRANS_BITS + 1) * 2; break;
-    case IDENTITY: bits = 0; break;
-    default: assert(0); return 0;
-  }
-  assert(type < GLOBAL_TRANS_TYPES);
-  return bits ? (bits << AV1_PROB_COST_SHIFT) + gmtype_cost[type] : 0;
+static int get_gmbitcost(const AV1_COMP *const cpi,
+                         const WarpedMotionParams *gm) {
+  static const int gm_params_cost[TRANS_TYPES] = {
+    GM_IDENTITY_BITS, GM_TRANSLATION_BITS, GM_ROTZOOM_BITS,
+    GM_AFFINE_BITS,   GM_HOMOGRAPHY_BITS,
+  };
+  const int cost = (gm_params_cost[gm->wmtype] << AV1_PROB_COST_SHIFT) +
+                   cpi->gmtype_cost[gm->wmtype];
+  assert(gm->wmtype < GLOBAL_TRANS_TYPES);
+  return cost;
 }
 
 #define GLOBAL_MOTION_RATE(ref)                                         \
   (cpi->global_motion_used[ref] >= GLOBAL_MOTION_COST_AMORTIZATION_BLKS \
        ? 0                                                              \
-       : get_gmbitcost(&cm->global_motion[(ref)],                       \
-                       cm->fc->global_motion_types_prob) /              \
+       : get_gmbitcost(cpi, &cm->global_motion[(ref)]) /                \
              GLOBAL_MOTION_COST_AMORTIZATION_BLKS)
 #else
 #define GLOBAL_MOTION_RATE(ref) 0