From d9655e42b84a405a291ad142df748cc7e0364916 Mon Sep 17 00:00:00 2001
From: Deb Mukherjee <debargha@google.com>
Date: Thu, 10 Oct 2013 17:24:55 -0700
Subject: [PATCH] Change in rddiv parameter to make it a power of 2

Converts the constant rddiv parameter to 128 (from 100) and
implements RDCOST with bit-shift rather than multiplication.
Other parameters are also adjusted to roughly keep the same
balance between Rate and Distortion.

There is a slight speed-up of about 0.5-1% (at speed 0) as
testted on football_cif.

There is a slight change in performance due to small change
in the parameters.
derfraw300: +0.033%
stdhdraw250; +0.102%

Change-Id: I70ac69f58fa71c83108f68fe41796cd19d1fc760
---
 vp9/encoder/vp9_rdopt.c | 21 +++++++++++++++------
 vp9/encoder/vp9_rdopt.h |  4 +++-
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index f1946f9..ed2994e 100644
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -110,6 +110,7 @@ static int rd_thresh_block_size_factor[BLOCK_SIZES] =
 #define RD_THRESH_MAX_FACT 64
 #define RD_THRESH_INC      1
 #define RD_THRESH_POW      1.25
+#define RD_MULT_EPB_RATIO  64
 
 #define MV_COST_WEIGHT      108
 #define MV_COST_WEIGHT_SUB  120
@@ -162,7 +163,17 @@ void vp9_init_me_luts() {
 
 static int compute_rd_mult(int qindex) {
   const int q = vp9_dc_quant(qindex, 0);
-  return (11 * q * q) >> 2;
+  // TODO(debargha): Adjust the function below
+  return (88 * q * q / 25);
+}
+
+static int compute_rd_thresh_factor(int qindex) {
+  int q;
+  // TODO(debargha): Adjust the function below
+  q = (int)(pow(vp9_dc_quant(qindex, 0) / 4.0, RD_THRESH_POW) * 5.12);
+  if (q < 8)
+    q = 8;
+  return q;
 }
 
 void vp9_initialize_me_consts(VP9_COMP *cpi, int qindex) {
@@ -172,9 +183,7 @@ void vp9_initialize_me_consts(VP9_COMP *cpi, int qindex) {
 
 static void set_block_thresholds(VP9_COMP *cpi, int qindex) {
   int q, i, bsize;
-  q = ((int)pow(vp9_dc_quant(qindex, 0) >> 2, RD_THRESH_POW)) << 2;
-  if (q < 8)
-    q = 8;
+  q = compute_rd_thresh_factor(qindex);
 
   for (bsize = 0; bsize < BLOCK_SIZES; ++bsize) {
     for (i = 0; i < MAX_MODES; ++i) {
@@ -216,7 +225,7 @@ void vp9_initialize_rd_consts(VP9_COMP *cpi, int qindex) {
   //     cpi->common.refresh_alt_ref_frame)
   qindex = clamp(qindex, 0, MAXQ);
 
-  cpi->RDDIV = 100;
+  cpi->RDDIV = RDDIV_BITS;  // in bits (to multiply D by 128)
   cpi->RDMULT = compute_rd_mult(qindex);
   if (cpi->pass == 2 && (cpi->common.frame_type != KEY_FRAME)) {
     if (cpi->twopass.next_iiratio > 31)
@@ -225,7 +234,7 @@ void vp9_initialize_rd_consts(VP9_COMP *cpi, int qindex) {
       cpi->RDMULT +=
           (cpi->RDMULT * rd_iifactor[cpi->twopass.next_iiratio]) >> 4;
   }
-  cpi->mb.errorperbit = cpi->RDMULT >> 6;
+  cpi->mb.errorperbit = cpi->RDMULT / RD_MULT_EPB_RATIO;
   cpi->mb.errorperbit += (cpi->mb.errorperbit == 0);
 
   vp9_set_speed_features(cpi);
diff --git a/vp9/encoder/vp9_rdopt.h b/vp9/encoder/vp9_rdopt.h
index c86ea27..aa4068d 100644
--- a/vp9/encoder/vp9_rdopt.h
+++ b/vp9/encoder/vp9_rdopt.h
@@ -12,8 +12,10 @@
 #ifndef VP9_ENCODER_VP9_RDOPT_H_
 #define VP9_ENCODER_VP9_RDOPT_H_
 
+#define RDDIV_BITS          7
+
 #define RDCOST(RM, DM, R, D) \
-  (((128 + ((int64_t)R) * (RM)) >> 8) + ((int64_t)DM) * (D))
+  (((128 + ((int64_t)R) * (RM)) >> 8) + (D << DM))
 #define QIDX_SKIP_THRESH     115
 
 void vp9_initialize_rd_consts(VP9_COMP *cpi, int qindex);
-- 
2.7.4