Change to update of rate control factors.

Remove damping parameter and use the damping
formula introduced by Yaowu Xu in all cases.

Change-Id: I18db7e0d0f262d5140102f259ab07821d374d285

vp9/encoder/vp9_encoder.c

diff --git a/vp9/encoder/vp9_encoder.c b/vp9/encoder/vp9_encoder.c
index c85bf2a..e938427 100644
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -2955,18 +2955,18 @@
 
           if (undershoot_seen || loop_count > 1) {
             // Update rate_correction_factor unless
-            vp9_rc_update_rate_correction_factors(cpi, 1);
+            vp9_rc_update_rate_correction_factors(cpi);
 
             q = (q_high + q_low + 1) / 2;
           } else {
             // Update rate_correction_factor unless
-            vp9_rc_update_rate_correction_factors(cpi, 0);
+            vp9_rc_update_rate_correction_factors(cpi);
 
             q = vp9_rc_regulate_q(cpi, rc->this_frame_target,
                                    bottom_index, MAX(q_high, top_index));
 
             while (q < q_low && retries < 10) {
-              vp9_rc_update_rate_correction_factors(cpi, 0);
+              vp9_rc_update_rate_correction_factors(cpi);
               q = vp9_rc_regulate_q(cpi, rc->this_frame_target,
                                      bottom_index, MAX(q_high, top_index));
               retries++;
@@ -2979,10 +2979,10 @@
           q_high = q > q_low ? q - 1 : q_low;
 
           if (overshoot_seen || loop_count > 1) {
-            vp9_rc_update_rate_correction_factors(cpi, 1);
+            vp9_rc_update_rate_correction_factors(cpi);
             q = (q_high + q_low) / 2;
           } else {
-            vp9_rc_update_rate_correction_factors(cpi, 0);
+            vp9_rc_update_rate_correction_factors(cpi);
             q = vp9_rc_regulate_q(cpi, rc->this_frame_target,
                                    bottom_index, top_index);
             // Special case reset for qlow for constrained quality.
@@ -2995,7 +2995,7 @@
             }
 
             while (q > q_high && retries < 10) {
-              vp9_rc_update_rate_correction_factors(cpi, 0);
+              vp9_rc_update_rate_correction_factors(cpi);
               q = vp9_rc_regulate_q(cpi, rc->this_frame_target,
                                      bottom_index, top_index);
               retries++;

vp9/encoder/vp9_ratectrl.c

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index 21f4cce..11da367 100644
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -396,7 +396,7 @@
   }
 }
 
-void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi, int damp_var) {
+void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi) {
   const VP9_COMMON *const cm = &cpi->common;
   int correction_factor = 100;
   double rate_correction_factor = get_rate_correction_factor(cpi);
@@ -431,19 +431,8 @@
 
   // More heavily damped adjustment used if we have been oscillating either side
   // of target.
-  switch (damp_var) {
-    case 0:
-      adjustment_limit = 0.75;
-      break;
-    case 1:
-      adjustment_limit = 0.25 +
-          0.5 * MIN(1, fabs(log10(0.01 * correction_factor)));
-      break;
-    case 2:
-    default:
-      adjustment_limit = 0.25;
-      break;
-  }
+  adjustment_limit = 0.25 +
+      0.5 * MIN(1, fabs(log10(0.01 * correction_factor)));
 
   cpi->rc.q_2_frame = cpi->rc.q_1_frame;
   cpi->rc.q_1_frame = cm->base_qindex;
@@ -1222,9 +1211,7 @@
   rc->projected_frame_size = (int)(bytes_used << 3);
 
   // Post encode loop adjustment of Q prediction.
-  vp9_rc_update_rate_correction_factors(
-      cpi, (cpi->sf.recode_loop >= ALLOW_RECODE_KFARFGF) ? 2 :
-            ((oxcf->rc_mode == VPX_CBR) ? 1 : 0));
+  vp9_rc_update_rate_correction_factors(cpi);
 
   // Keep a record of last Q and ambient average Q.
   if (cm->frame_type == KEY_FRAME) {

vp9/encoder/vp9_ratectrl.h

diff --git a/vp9/encoder/vp9_ratectrl.h b/vp9/encoder/vp9_ratectrl.h
index a53f4e0..9774127 100644
--- a/vp9/encoder/vp9_ratectrl.h
+++ b/vp9/encoder/vp9_ratectrl.h
@@ -160,7 +160,7 @@
 
 // Updates rate correction factors
 // Changes only the rate correction factors in the rate control structure.
-void vp9_rc_update_rate_correction_factors(struct VP9_COMP *cpi, int damp_var);
+void vp9_rc_update_rate_correction_factors(struct VP9_COMP *cpi);
 
 // Decide if we should drop this frame: For 1-pass CBR.
 // Changes only the decimation count in the rate control structure