From 740688c67dafb9d1c6c597df9d0cdbb6dec5c3ee Mon Sep 17 00:00:00 2001
From: Jaakko Laitinen <jaakko.laitinen@tuni.fi>
Date: Tue, 31 Mar 2020 11:56:44 +0300
Subject: [PATCH] Add auto option to intra qp offset

---
 src/cfg.c     | 5 +++++
 src/encoder.c | 4 ++++
 src/kvazaar.h | 1 +
 3 files changed, 10 insertions(+)

diff --git a/src/cfg.c b/src/cfg.c
index efc58db9..f286fb99 100644
--- a/src/cfg.c
+++ b/src/cfg.c
@@ -42,6 +42,7 @@ int kvz_config_init(kvz_config *cfg)
   cfg->framerate_denom = 1;
   cfg->qp              = 22;
   cfg->intra_qp_offset = 0;
+  cfg->intra_qp_offset_auto = false;
   cfg->intra_period    = 64;
   cfg->vps_period      = 0;
   cfg->deblock_enable  = 1;
@@ -1024,6 +1025,10 @@ int kvz_config_parse(kvz_config *cfg, const char *name, const char *value)
   }
   else if OPT("intra-qp-offset") {
     cfg->intra_qp_offset = atoi(value);
+    if( cfg->intra_qp_offset == 0 && !strcmp( value, "auto" ) )
+    {
+        cfg->intra_qp_offset_auto = true;
+    }
   }
   else if OPT("open-gop") {
     cfg->open_gop = (bool)atobool(value);
diff --git a/src/encoder.c b/src/encoder.c
index ffddfe02..b6c49a21 100644
--- a/src/encoder.c
+++ b/src/encoder.c
@@ -243,6 +243,10 @@ encoder_control_t* kvz_encoder_control_init(const kvz_config *const cfg)
     }
   } 
   
+  if( encoder->cfg.intra_qp_offset_auto ) {
+      encoder->cfg.intra_qp_offset = encoder->cfg.gop_len > 1 ? -kvz_math_ceil_log2( encoder->cfg.gop_len ) + 1 : 0;
+  }
+
   // Disable GOP and QP offset for all-intra coding
   if (encoder->cfg.intra_period == 1) {
     encoder->cfg.gop_len = 0;
diff --git a/src/kvazaar.h b/src/kvazaar.h
index 8792cbc6..83109559 100644
--- a/src/kvazaar.h
+++ b/src/kvazaar.h
@@ -387,6 +387,7 @@ typedef struct kvz_config
 
   /** \brief Offset to add to QP for intra frames */
   int8_t intra_qp_offset;
+  uint8_t intra_qp_offset_auto;
 
   /** \brief Minimum QP that uses CABAC for residual cost instead of a fast estimate. */
   int8_t fast_residual_cost_limit;