[x265-commits] [x265] TComRom: hard-code the lambda tables

[Steve Borho]

details:   http://hg.videolan.org/x265/rev/4f7658b3c78a
branches:  
changeset: 6789:4f7658b3c78a
user:      Steve Borho <steve at borho.org>
date:      Mon Apr 28 13:17:25 2014 -0500
description:
TComRom: hard-code the lambda tables

diffstat:

 source/Lib/TLibCommon/TComRom.cpp |  48 +++++++++++++++++++++++++++-----------
 source/Lib/TLibCommon/TComRom.h   |   4 +-
 2 files changed, 36 insertions(+), 16 deletions(-)

diffs (80 lines):

diff -r 84d31cb2aeab -r 4f7658b3c78a source/Lib/TLibCommon/TComRom.cpp
--- a/source/Lib/TLibCommon/TComRom.cpp	Mon Apr 28 18:54:09 2014 +0530
+++ b/source/Lib/TLibCommon/TComRom.cpp	Mon Apr 28 13:17:25 2014 -0500
@@ -126,19 +126,41 @@ public:
     }
 };
 
-double x265_lambda_tab[MAX_MAX_QP + 1];
-double x265_lambda2_tab[MAX_MAX_QP + 1];
+// lambda = pow(2, (double)q / 6 - 2);
+const double x265_lambda_tab[MAX_MAX_QP + 1] = {
+    0.2500, 0.2806, 0.3150, 0.3536, 0.3969, 
+    0.4454, 0.5000, 0.5612, 0.6300, 0.7071, 
+    0.7937, 0.8909, 1.0000, 1.1225, 1.2599, 
+    1.4142, 1.5874, 1.7818, 2.0000, 2.2449, 
+    2.5198, 2.8284, 3.1748, 3.5636, 4.0000, 
+    4.4898, 5.0397, 5.6569, 6.3496, 7.1272, 
+    8.0000, 8.9797, 10.0794, 11.3137, 12.6992, 
+    14.2544, 16.0000, 17.9594, 20.1587, 22.6274, 
+    25.3984, 28.5088, 32.0000, 35.9188, 40.3175, 
+    45.2548, 50.7968, 57.0175, 64.0000, 71.8376, 
+    80.6349, 90.5097, 101.5937, 114.0350, 128.0000, 
+    143.6751, 161.2699, 181.0193, 203.1873, 228.0701, 
+    256.0000, 287.3503, 322.5398, 362.0387, 406.3747, 
+    456.1401, 512.0000, 574.7006, 645.0796, 724.0773
+};
 
-static void initLambda(double scale)
-{
-    for (int q = 0; q <= MAX_MAX_QP; q++)
-    {
-        double lambda = pow(2, (double)q / 6 - 2);
-
-        x265_lambda_tab[q]  = lambda;
-        x265_lambda2_tab[q] = pow(lambda, 2) * scale;
-    }
-}
+// lambda2 = pow(lambda, 2) * scale (0.85);
+const double x265_lambda2_tab[MAX_MAX_QP + 1] = {
+    0.0531, 0.0669, 0.0843, 0.1063, 0.1339, 
+    0.1687, 0.2125, 0.2677, 0.3373, 0.4250, 
+    0.5355, 0.6746, 0.8500, 1.0709, 1.3493, 
+    1.7000, 2.1419, 2.6986, 3.4000, 4.2837, 
+    5.3972, 6.8000, 8.5675, 10.7943, 13.6000, 
+    17.1349, 21.5887, 27.2000, 34.2699, 43.1773, 
+    54.4000, 68.5397, 86.3546, 108.8000, 137.0794, 
+    172.7092, 217.6000, 274.1588, 345.4185, 435.2000, 
+    548.3176, 690.8369, 870.4000, 1096.6353, 1381.6739, 
+    1740.8000, 2193.2706, 2763.3478, 3481.6000, 4386.5411, 
+    5526.6955, 6963.2000, 8773.0823, 11053.3910, 13926.4000, 
+    17546.1645, 22106.7820, 27852.8000, 35092.3290, 44213.5640, 
+    55705.6000, 70184.6580, 88427.1280, 111411.2000, 140369.3161, 
+    176854.2561, 222822.4000, 280738.6321, 353708.5122, 445644.8000
+};
 
 static int initialized /* = 0 */;
 
@@ -148,8 +170,6 @@ void initROM()
     if (ATOMIC_CAS32(&initialized, 0, 1) == 1)
         return;
 
-    initLambda(0.85);
-
     int i, c;
 
     // g_aucConvertToBit[ x ]: log2(x/4), if x=4 -> 0, x=8 -> 1, x=16 -> 2, ...
diff -r 84d31cb2aeab -r 4f7658b3c78a source/Lib/TLibCommon/TComRom.h
--- a/source/Lib/TLibCommon/TComRom.h	Mon Apr 28 18:54:09 2014 +0530
+++ b/source/Lib/TLibCommon/TComRom.h	Mon Apr 28 13:17:25 2014 -0500
@@ -271,8 +271,8 @@ extern const uint32_t g_scalingListNum[S
 extern const int g_winUnitX[MAX_CHROMA_FORMAT_IDC + 1];
 extern const int g_winUnitY[MAX_CHROMA_FORMAT_IDC + 1];
 
-extern double x265_lambda_tab[MAX_MAX_QP + 1];
-extern double x265_lambda2_tab[MAX_MAX_QP + 1];
+extern const double x265_lambda_tab[MAX_MAX_QP + 1];
+extern const double x265_lambda2_tab[MAX_MAX_QP + 1];
 
 // CABAC tables
 extern const uint8_t g_lpsTable[64][4];