commit a37ee9d2e8b9b7cf33455af60bcd9312dc898126
author John Koleszar <jkoleszar@google.com> Wed May 08 16:14:14 2013 -0700
committer Gerrit Code Review <gerrit@gerrit.golo.chromium.org> Thu May 09 20:14:39 2013 -0700
tree 246646e203b0ec450ada4e0681e1c6f8e04397f7
parent 6dab4d205e5c3cb51fc104109359a41f9c1b9111

Fix non-4:2:0 chroma MV calculation for SPLITMV

The previous code was somewhat vestigial for 16x16 MI units, but was
incorrect when called with chroma blocks larger than 4x4 because the
block index caused a reference to a non-existent BMI. This patch uses
the same MV for all chroma subblocks in SPLITMV mode, which is
suboptimal for non-4:2:0 subsamplings, but as SPLITMV may be removed
in the near future, will use this as a stop gap.

Change-Id: I3211cee5ccf1cfb426e5eef5353b0ce5bb92b4cd

vp9/common/vp9_reconinter.c

diff --git a/vp9/common/vp9_reconinter.c b/vp9/common/vp9_reconinter.c
index 0f5cbf4..3668fcd 100644
--- a/vp9/common/vp9_reconinter.c
+++ b/vp9/common/vp9_reconinter.c
@@ -257,22 +257,19 @@
   return (value < 0 ? value - 2 : value + 2) / 4;
 }
 
-#define IDX1 2
-#define IDX2 3
-
-static int mi_mv_pred_row_q4(MACROBLOCKD *mb, int off, int idx) {
-  const int temp = mb->mode_info_context->bmi[off + 0].as_mv[idx].as_mv.row +
-                   mb->mode_info_context->bmi[off + 1].as_mv[idx].as_mv.row +
-                   mb->mode_info_context->bmi[off + IDX1].as_mv[idx].as_mv.row +
-                   mb->mode_info_context->bmi[off + IDX2].as_mv[idx].as_mv.row;
+static int mi_mv_pred_row_q4(MACROBLOCKD *mb, int idx) {
+  const int temp = mb->mode_info_context->bmi[0].as_mv[idx].as_mv.row +
+                   mb->mode_info_context->bmi[1].as_mv[idx].as_mv.row +
+                   mb->mode_info_context->bmi[2].as_mv[idx].as_mv.row +
+                   mb->mode_info_context->bmi[3].as_mv[idx].as_mv.row;
   return round_mv_comp_q4(temp);
 }
 
-static int mi_mv_pred_col_q4(MACROBLOCKD *mb, int off, int idx) {
-  const int temp = mb->mode_info_context->bmi[off + 0].as_mv[idx].as_mv.col +
-                   mb->mode_info_context->bmi[off + 1].as_mv[idx].as_mv.col +
-                   mb->mode_info_context->bmi[off + IDX1].as_mv[idx].as_mv.col +
-                   mb->mode_info_context->bmi[off + IDX2].as_mv[idx].as_mv.col;
+static int mi_mv_pred_col_q4(MACROBLOCKD *mb, int idx) {
+  const int temp = mb->mode_info_context->bmi[0].as_mv[idx].as_mv.col +
+                   mb->mode_info_context->bmi[1].as_mv[idx].as_mv.col +
+                   mb->mode_info_context->bmi[2].as_mv[idx].as_mv.col +
+                   mb->mode_info_context->bmi[3].as_mv[idx].as_mv.col;
   return round_mv_comp_q4(temp);
 }
 
@@ -351,9 +348,12 @@
       if (plane == 0) {
         mv = &xd->mode_info_context->bmi[block].as_mv[which_mv].as_mv;
       } else {
-        const int y_block = (block & 2) * 4 + (block & 1) * 2;
-        split_chroma_mv.row = mi_mv_pred_row_q4(xd, y_block, which_mv);
-        split_chroma_mv.col = mi_mv_pred_col_q4(xd, y_block, which_mv);
+        // TODO(jkoleszar): All chroma MVs in SPLITMV mode are taken as the
+        // same MV (the average of the 4 luma MVs) but we could do something
+        // smarter for non-4:2:0. Just punt for now, pending the changes to get
+        // rid of SPLITMV mode entirely.
+        split_chroma_mv.row = mi_mv_pred_row_q4(xd, which_mv);
+        split_chroma_mv.col = mi_mv_pred_col_q4(xd, which_mv);
         mv = &split_chroma_mv;
       }
     } else {