Fix border check in MOTION_VAR

Correct distance to right and bottom edge when predicting the overlapping
region using neighbor predictors. The distance is more than that for the
whole block, so the condition in clamp_mv will be looser.

Change-Id: I40dfdd9c0a2a5e854cac12195b282493981e9d93

av1/common/reconinter.c

@@ -477,9 +477,11 @@ void av1_build_prediction_by_above_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
   const TileInfo *const tile = &xd->tile;
   BLOCK_SIZE bsize = xd->mi[0]->mbmi.sb_type;
   int i, j, mi_step, ref;
+  int mb_to_right_edge_base = xd->mb_to_right_edge;
 
   if (mi_row <= tile->mi_row_start) return;
 
+  xd->mb_to_bottom_edge += xd->n8_h * 32;
   for (i = 0; i < AOMMIN(xd->n8_w, cm->mi_cols - mi_col); i += mi_step) {
     int mi_row_offset = -1;
     int mi_col_offset = i;
@@ -509,6 +511,8 @@ void av1_build_prediction_by_above_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
     }
 
     xd->mb_to_left_edge = -(((mi_col + i) * MI_SIZE) * 8);
+    xd->mb_to_right_edge =
+        mb_to_right_edge_base + (xd->n8_w - i - mi_step) * 64;
     mi_x = (mi_col + i) << MI_SIZE_LOG2;
     mi_y = mi_row << MI_SIZE_LOG2;
 
@@ -544,6 +548,8 @@ void av1_build_prediction_by_above_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
     }
   }
   xd->mb_to_left_edge = -((mi_col * MI_SIZE) * 8);
+  xd->mb_to_right_edge = mb_to_right_edge_base;
+  xd->mb_to_bottom_edge -= xd->n8_h * 32;
 }
 
 void av1_build_prediction_by_left_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
@@ -553,9 +559,11 @@ void av1_build_prediction_by_left_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
   const TileInfo *const tile = &xd->tile;
   BLOCK_SIZE bsize = xd->mi[0]->mbmi.sb_type;
   int i, j, mi_step, ref;
+  int mb_to_bottom_edge_base = xd->mb_to_bottom_edge;
 
   if (mi_col - 1 < tile->mi_col_start) return;
 
+  xd->mb_to_right_edge += xd->n8_w * 32;
   for (i = 0; i < AOMMIN(xd->n8_h, cm->mi_rows - mi_row); i += mi_step) {
     int mi_row_offset = i;
     int mi_col_offset = -1;
@@ -585,6 +593,8 @@ void av1_build_prediction_by_left_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
     }
 
     xd->mb_to_top_edge = -(((mi_row + i) * MI_SIZE) * 8);
+    xd->mb_to_bottom_edge =
+        mb_to_bottom_edge_base + (xd->n8_h - i - mi_step) * 64;
     mi_x = mi_col << MI_SIZE_LOG2;
     mi_y = (mi_row + i) << MI_SIZE_LOG2;
 
@@ -620,6 +630,8 @@ void av1_build_prediction_by_left_preds(const AV1_COMMON *cm, MACROBLOCKD *xd,
     }
   }
   xd->mb_to_top_edge = -((mi_row * MI_SIZE) * 8);
+  xd->mb_to_bottom_edge = mb_to_bottom_edge_base;
+  xd->mb_to_right_edge -= xd->n8_w * 32;
 }
 
 void av1_build_obmc_inter_predictors_sb(const AV1_COMMON *cm, MACROBLOCKD *xd,