From 81043e8d625efbafe0668b6b04f3dc812b65c4a4 Mon Sep 17 00:00:00 2001
From: Paul Wilkins <paulwilkins@google.com>
Date: Tue, 5 Feb 2013 10:28:26 +0000
Subject: [PATCH] Change definition of NearestMV.

This commit makes the NearestMV match the chosen
best reference MV. It can be a 0,0 or non zero vector
which means the the compound nearest mv mode can
combine a 0,0 and a non zero vector.

Change-Id: I2213d09996ae2916e53e6458d7d110350dcffd7a
---
 vp9/common/vp9_findnearmv.c | 23 +++++++++--------------
 vp9/encoder/vp9_rdopt.c     |  7 +------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/vp9/common/vp9_findnearmv.c b/vp9/common/vp9_findnearmv.c
index 88f2ea9c1..9585611dd 100644
--- a/vp9/common/vp9_findnearmv.c
+++ b/vp9/common/vp9_findnearmv.c
@@ -279,21 +279,16 @@ void vp9_find_best_ref_mvs(MACROBLOCKD *xd,
     clamp_mv2(&sorted_mvs[i], xd);
   }
 
-  // Provided that there are non zero vectors available there will not
-  // be more than one 0,0 entry in the sorted list.
-  // The best ref mv is always set to the first entry (which gave the best
-  // results. The nearest is set to the first non zero vector if available and
-  // near to the second non zero vector if available.
-  // We do not use 0,0 as a nearest or near as 0,0 has its own mode.
-  if ( sorted_mvs[0].as_int ) {
-    nearest->as_int = sorted_mvs[0].as_int;
-    if ( sorted_mvs[1].as_int )
-      near->as_int = sorted_mvs[1].as_int;
-    else
-      near->as_int = sorted_mvs[2].as_int;
+  // Nearest may be a 0,0 or non zero vector and now matches the chosen
+  // "best reference". This has advantages when it is used as part of a
+  // compound predictor as it means a non zero vector can be paired using
+  // this mode with a 0 vector. The Near vector is still forced to be a
+  // non zero candidate if one is avaialble.
+  nearest->as_int = sorted_mvs[0].as_int;
+  if ( sorted_mvs[1].as_int ) {
+    near->as_int = sorted_mvs[1].as_int;
   } else {
-      nearest->as_int = sorted_mvs[1].as_int;
-      near->as_int = sorted_mvs[2].as_int;
+    near->as_int = sorted_mvs[2].as_int;
   }
 
   // Copy back the re-ordered mv list
diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index 2e9bbcfc1..110e07057 100644
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -3301,13 +3301,8 @@ static int64_t handle_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
                                   96, xd->allow_high_precision_mv);
       }
       break;
-    case NEARESTMV:
     case NEARMV:
-      // Do not bother proceeding if the vector (from newmv, nearest or
-      // near) is 0,0 as this should then be coded using the zeromv mode.
-      for (i = 0; i < num_refs; ++i)
-        if (frame_mv[this_mode][refs[i]].as_int == 0)
-          return INT64_MAX;
+    case NEARESTMV:
     case ZEROMV:
     default:
       break;