Handle partition type coding of boundary blocks

The partition types of blocks sitting on the frame boundary are
constrained by the block size and the position of each sub-block
relative to the frame. Hence we use truncated probability models
to handle the coding of such information.

100 frames run:
yt 0.138%

Change-Id: I85d9b45665c15280069c0234ea6f778af586d87d

1 files changed, 11 insertions, 2 deletions

diff --git a/vp9/decoder/vp9_decodframe.c b/vp9/decoder/vp9_decodframe.c
index aacdad528..1d9233c88 100644
--- a/vp9/decoder/vp9_decodframe.c
+++ b/vp9/decoder/vp9_decodframe.c
@@ -469,12 +469,21 @@ static void decode_modes_sb(VP9D_COMP *pbi, int mi_row, int mi_col,
 
   if (bsize >= BLOCK_SIZE_SB8X8) {
     int pl;
+    int idx = check_bsize_coverage(pc, xd, mi_row, mi_col, bsize);
     // read the partition information
     xd->left_seg_context = pc->left_seg_context + (mi_row & MI_MASK);
     xd->above_seg_context = pc->above_seg_context + mi_col;
     pl = partition_plane_context(xd, bsize);
-    partition = treed_read(r, vp9_partition_tree,
-                           pc->fc.partition_prob[pc->frame_type][pl]);
+
+    if (idx == 0)
+      partition = treed_read(r, vp9_partition_tree,
+                             pc->fc.partition_prob[pc->frame_type][pl]);
+    else if (idx > 0 &&
+        !vp9_read(r, pc->fc.partition_prob[pc->frame_type][pl][idx]))
+      partition = (idx == 1) ? PARTITION_HORZ : PARTITION_VERT;
+    else
+      partition = PARTITION_SPLIT;
+
     pc->fc.partition_counts[pl][partition]++;
   }