[x265] [PATCH 2 of 2] intra: refine R-D candidate list

[deepthi at multicorewareinc.com]

# HG changeset patch
# User Deepthi Nandakumar <deepthi at multicorewareinc.com>
# Date 1447672473 -19800
#      Mon Nov 16 16:44:33 2015 +0530
# Node ID e2931ed967188d8b1b638363c9ff410c0e40a06b
# Parent  409424e8b1bd19a5e70236d364ca8cb7e03b5274
intra: refine R-D candidate list

Prevent wild card entries based on mpms - tests show there is high correlation
only for the first MPM candidate.

diff -r 409424e8b1bd -r e2931ed96718 source/encoder/search.cpp
--- a/source/encoder/search.cpp	Mon Nov 16 13:42:43 2015 +0530
+++ b/source/encoder/search.cpp	Mon Nov 16 16:44:33 2015 +0530
@@ -1534,9 +1534,10 @@
                 for (int i = 0; i < maxCandCount; i++)
                     candCostList[i] = MAX_INT64;
 
-                uint64_t paddedBcost = bcost + (bcost >> 3); // 1.12%
+                uint64_t paddedBcost = bcost + (bcost >> 2); // 1.25%
                 for (int mode = 0; mode < 35; mode++)
-                    if (modeCosts[mode] < paddedBcost || (mpms & ((uint64_t)1 << mode)))
+                    if ((modeCosts[mode] < paddedBcost) || ((uint32_t)mode == mpmModes[0])) 
+                        /* choose for R-D analysis only if this mode passes cost threshold or matches MPM[0] */
                         updateCandList(mode, modeCosts[mode], maxCandCount, rdModeList, candCostList);
             }