shithub: libvpx

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ref: ad43a73883b2e18e07fc30f82486e83bf1746cdb
parent: 0a3593a55571e2ceca45fece9b7f7430a0cc3304
author: Alex Converse <[email protected]>
date: Mon Feb 1 04:47:39 EST 2016 

Fix a signed overflow in vp9 motion cost.

Change-Id: I5975e3aede62202d8ee6ced33889350c0a56554a


--- a/vp9/encoder/vp9_mcomp.c
+++ b/vp9/encoder/vp9_mcomp.c
@@ -86,7 +86,9 @@
   if (mvcost) {
     const MV diff = { mv->row - ref->row,
                       mv->col - ref->col };
-    return ROUND_POWER_OF_TWO(mv_cost(&diff, mvjcost, mvcost) *
+    // TODO(aconverse): See if this shift needs to be tied to
+    // VP9_PROB_COST_SHIFT.
+    return ROUND_POWER_OF_TWO((unsigned)mv_cost(&diff, mvjcost, mvcost) *
                                   error_per_bit, 13);
   }
   return 0;
@@ -96,8 +98,9 @@
                           int error_per_bit) {
   const MV diff = { mv->row - ref->row,
                     mv->col - ref->col };
-  return ROUND_POWER_OF_TWO(mv_cost(&diff, x->nmvjointsadcost,
-                                    x->nmvsadcost) * error_per_bit, 8);
+  // TODO(aconverse): See if this shift needs to be tied to VP9_PROB_COST_SHIFT.
+  return ROUND_POWER_OF_TWO((unsigned)mv_cost(&diff, x->nmvjointsadcost,
+                                      x->nmvsadcost) * error_per_bit, 8);
 }
 
 void vp9_init_dsmotion_compensation(search_site_config *cfg, int stride) {