Use dummy first-pass frame in CTC

Use a dummy first-pass frame in CTC settings. Avoid exercising
first-pass stats in the encoding process therein.

Change-Id: Ibc8498e826672444299a7b75d5e2f5d134c9af78
(cherry picked from commit cab784db520b8b6c5ab98cf066f9a772030f9dd0)

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index a4fcba6..b5fa6a3 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -3638,7 +3638,10 @@
 
   if (is_stat_generation_stage(cpi)) {
 #if !CONFIG_REALTIME_ONLY
-    av1_first_pass(cpi, frame_input->ts_duration);
+    if (cpi->oxcf.q_cfg.use_fixed_qp_offsets)
+      av1_dummy_first_pass_frame(cpi, frame_input->ts_duration);
+    else
+      av1_first_pass(cpi, frame_input->ts_duration);
 #endif
   } else if (cpi->oxcf.pass == AOM_RC_ONE_PASS ||
              cpi->oxcf.pass >= AOM_RC_SECOND_PASS) {

av1/encoder/firstpass.c

diff --git a/av1/encoder/firstpass.c b/av1/encoder/firstpass.c
index af1e8c1..21fcd16 100644
--- a/av1/encoder/firstpass.c
+++ b/av1/encoder/firstpass.c
@@ -1207,6 +1207,21 @@
   }
 }
 
+void av1_dummy_first_pass_frame(AV1_COMP *cpi, const int64_t ts_duration) {
+  AV1_COMMON *const cm = &cpi->common;
+  CurrentFrame *const current_frame = &cm->current_frame;
+  const CommonModeInfoParams *const mi_params = &cm->mi_params;
+  const int unit_rows = get_unit_rows(BLOCK_16X16, mi_params->mb_rows);
+  const int unit_cols = get_unit_cols(BLOCK_16X16, mi_params->mb_cols);
+  setup_firstpass_data(cm, &cpi->firstpass_data, unit_rows, unit_cols);
+  FRAME_STATS *mb_stats = cpi->firstpass_data.mb_stats;
+  FRAME_STATS stats = accumulate_frame_stats(mb_stats, unit_rows, unit_cols);
+  free_firstpass_data(&cpi->firstpass_data);
+  update_firstpass_stats(cpi, &stats, 1.0, current_frame->frame_number,
+                         ts_duration, BLOCK_16X16);
+  return;
+}
+
 void av1_first_pass(AV1_COMP *cpi, const int64_t ts_duration) {
   MACROBLOCK *const x = &cpi->td.mb;
   AV1_COMMON *const cm = &cpi->common;
@@ -1216,6 +1231,7 @@
   const int num_planes = av1_num_planes(cm);
   MACROBLOCKD *const xd = &x->e_mbd;
   const int qindex = find_fp_qindex(seq_params->bit_depth);
+
   // Detect if the key frame is screen content type.
   if (frame_is_intra_only(cm)) {
     FeatureFlags *const features = &cm->features;

av1/encoder/firstpass.h

diff --git a/av1/encoder/firstpass.h b/av1/encoder/firstpass.h
index 88f9b27..078e0e5 100644
--- a/av1/encoder/firstpass.h
+++ b/av1/encoder/firstpass.h
@@ -574,6 +574,8 @@
  */
 void av1_first_pass(struct AV1_COMP *cpi, const int64_t ts_duration);
 
+void av1_dummy_first_pass_frame(struct AV1_COMP *cpi,
+                                const int64_t ts_duration);
 #ifdef __cplusplus
 }  // extern "C"
 #endif