Extension of segmentation to 8 segments.

Also some further simplification following removal
of top node code.

There is an issue in regards to the shared file vp8cx.h
in regard to the roi_map as this interface assumes that
there are only 4 segments. I have left the value here as
4 for now meaning that the roi_map interface is broken
for VP9.

Note that this change would have been easier if I hadn't
had to search for hard wire instances of the number 4
and <= 3.

Change-Id: Ia8b6deea4be4dbd20deb1656e689dd43a5f190e8

2 files changed, 17 insertions, 3 deletions

diff --git a/vp9/decoder/vp9_decodemv.c b/vp9/decoder/vp9_decodemv.c
index 801e41a43..5352a0839 100644
--- a/vp9/decoder/vp9_decodemv.c
+++ b/vp9/decoder/vp9_decodemv.c
@@ -75,8 +75,22 @@ static MB_PREDICTION_MODE read_uv_mode(vp9_reader *r, const vp9_prob *p) {
 
 static int read_mb_segid(vp9_reader *r, MACROBLOCKD *xd) {
   const vp9_prob *const p = xd->mb_segment_tree_probs;
-  return vp9_read(r, p[0]) ? 2 + vp9_read(r, p[2])
-                           :     vp9_read(r, p[1]);
+  int ret_val;
+
+  if (vp9_read(r, p[0])) {
+    if (vp9_read(r, p[4])) {
+      ret_val = 6 + vp9_read(r, p[6]);
+    } else {
+      ret_val = 4 + vp9_read(r, p[5]);
+    }
+  } else {
+    if (vp9_read(r, p[1])) {
+      ret_val = 2 + vp9_read(r, p[3]);
+    } else {
+      ret_val = vp9_read(r, p[2]);
+    }
+  }
+  return ret_val;
 }
 
 static void set_segment_id(VP9_COMMON *cm, MB_MODE_INFO *mbmi,
diff --git a/vp9/decoder/vp9_decodframe.c b/vp9/decoder/vp9_decodframe.c
index 2bd200ef7..864eb82fd 100644
--- a/vp9/decoder/vp9_decodframe.c
+++ b/vp9/decoder/vp9_decodframe.c
@@ -1107,7 +1107,7 @@ static void setup_segmentation(VP9_COMMON *pc, MACROBLOCKD *xd, vp9_reader *r) {
     xd->allow_implicit_segment_update = vp9_read_bit(r);
 #endif
   if (xd->update_mb_segmentation_map) {
-    for (i = 0; i < MB_FEATURE_TREE_PROBS; i++)
+    for (i = 0; i < MB_SEG_TREE_PROBS; i++)
       xd->mb_segment_tree_probs[i] = vp9_read_bit(r) ? vp9_read_prob(r)
                                                      : MAX_PROB;