Add option to signal zero dc_deltaq_ofs

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index b93230d..ae06ca4 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -473,6 +473,10 @@
     }
   }
 #if CONFIG_EXTQUANT
+#if ZERO_DC_DELTAQ_OFS
+    seq->base_y_dc_delta_q = 0;
+    seq->base_uv_dc_delta_q = 0;
+#else
   const int is_360p_or_larger =
       AOMMIN(seq->max_frame_width, seq->max_frame_height) >= 360;
   const int is_720p_or_larger =
@@ -487,6 +491,7 @@
     seq->base_y_dc_delta_q = -4;
     seq->base_uv_dc_delta_q = -3;
   }
+#endif
 #endif  // CONFIG_EXTQUANT
 }
 

build/cmake/aom_config_defaults.cmake

diff --git a/build/cmake/aom_config_defaults.cmake b/build/cmake/aom_config_defaults.cmake
index 5ba64e2..3993120 100644
--- a/build/cmake/aom_config_defaults.cmake
+++ b/build/cmake/aom_config_defaults.cmake
@@ -140,6 +140,8 @@
 set_aom_config_var(CONFIG_SDP 0 NUMBER "AV2 Semi-Decoupled Partitioning.")
 set_aom_config_var(CONFIG_EXTQUANT 1
                    "AV2 extended quantization experiment flag")
+set_aom_config_var(ZERO_DC_DELTAQ_OFS 1
+                   "AV2 set zero dc_deltaq offset")
 
 #
 # Variables in this section control optional features of the build system.