From e0454d36897d36263dc5f40235ed5ec6951a64e0 Mon Sep 17 00:00:00 2001
From: Deepa K G <deepa.kg@ittiam.com>
Date: Tue, 11 Dec 2018 17:38:06 +0530
Subject: [PATCH] Use undamped adjustment for rate correction factors

Undamped adjustment is used for the first frame
of each frame type while updating the rate
correction factors.

Change-Id: I42f80daa123c4cd4e45c18c6960cc7a67e7df7e6
---
 vp9/encoder/vp9_ratectrl.c | 17 +++++++++++++----
 vp9/encoder/vp9_ratectrl.h |  2 ++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index b5c002aea..52b14ea31 100644
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -417,6 +417,7 @@ void vp9_rc_init(const VP9EncoderConfig *oxcf, int pass, RATE_CONTROL *rc) {
 
   for (i = 0; i < RATE_FACTOR_LEVELS; ++i) {
     rc->rate_correction_factors[i] = 1.0;
+    rc->damped_adjustment[i] = 0;
   }
 
   rc->min_gf_interval = oxcf->min_gf_interval;
@@ -720,6 +721,8 @@ void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi) {
   int correction_factor = 100;
   double rate_correction_factor = get_rate_correction_factor(cpi);
   double adjustment_limit;
+  RATE_FACTOR_LEVEL rf_lvl =
+      cpi->twopass.gf_group.rf_level[cpi->twopass.gf_group.index];
 
   int projected_size_based_on_q = 0;
 
@@ -746,10 +749,16 @@ void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi) {
     correction_factor = (int)((100 * (int64_t)cpi->rc.projected_frame_size) /
                               projected_size_based_on_q);
 
-  // More heavily damped adjustment used if we have been oscillating either side
-  // of target.
-  adjustment_limit =
-      0.25 + 0.5 * VPXMIN(1, fabs(log10(0.01 * correction_factor)));
+  // Do not use damped adjustment for the first frame of each frame type
+  if (!cpi->rc.damped_adjustment[rf_lvl]) {
+    adjustment_limit = 1.0;
+    cpi->rc.damped_adjustment[rf_lvl] = 1;
+  } else {
+    // More heavily damped adjustment used if we have been oscillating either
+    // side of target.
+    adjustment_limit =
+        0.25 + 0.5 * VPXMIN(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;
diff --git a/vp9/encoder/vp9_ratectrl.h b/vp9/encoder/vp9_ratectrl.h
index a343bd34b..a5c1f4cf0 100644
--- a/vp9/encoder/vp9_ratectrl.h
+++ b/vp9/encoder/vp9_ratectrl.h
@@ -195,6 +195,8 @@ typedef struct {
   int use_post_encode_drop;
   // External flag to enable post encode frame dropping, controlled by user.
   int ext_use_post_encode_drop;
+
+  int damped_adjustment[RATE_FACTOR_LEVELS];
 } RATE_CONTROL;
 
 struct VP9_COMP;
-- 
2.40.0