Modify update golden reference update under aq-mode=3 mode.

For non-SVC 1 pass CBR: make the GF update interval a multiple of the
cyclic refresh period, and use encoding stats to prevent GF update at certain times.

Change-Id: I4c44cacc2f70f1d27391a47644837e1eaa065017

vp9/encoder/vp9_aq_cyclicrefresh.c

@@ -47,6 +47,7 @@ struct CYCLIC_REFRESH {
   int16_t motion_thresh;
   // Rate target ratio to set q delta.
   double rate_ratio_qdelta;
+  double low_content_avg;
 };
 
 CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) {
@@ -244,7 +245,7 @@ void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi,
 }
 
 // Update the actual number of blocks that were applied the segment delta q.
-void vp9_cyclic_refresh_update_actual_count(struct VP9_COMP *const cpi) {
+void vp9_cyclic_refresh_postencode(VP9_COMP *const cpi) {
   VP9_COMMON *const cm = &cpi->common;
   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
   unsigned char *const seg_map = cpi->segmentation_map;
@@ -257,6 +258,47 @@ void vp9_cyclic_refresh_update_actual_count(struct VP9_COMP *const cpi) {
   }
 }
 
+// Set golden frame update interval, for non-svc 1 pass CBR mode.
+void vp9_cyclic_refresh_set_golden_update(VP9_COMP *const cpi) {
+  RATE_CONTROL *const rc = &cpi->rc;
+  CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
+  // Set minimum gf_interval for GF update to a multiple (== 2) of refresh
+  // period. Depending on past encoding stats, GF flag may be reset and update
+  // may not occur until next baseline_gf_interval.
+  if (cr->percent_refresh > 0)
+    rc->baseline_gf_interval = 2 * (100 / cr->percent_refresh);
+  else
+    rc->baseline_gf_interval = 20;
+}
+
+// Update some encoding stats (from the just encoded frame), and if the golden
+// reference is to be updated check if we should NOT update the golden ref.
+void vp9_cyclic_refresh_check_golden_update(VP9_COMP *const cpi) {
+  VP9_COMMON *const cm = &cpi->common;
+  CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
+  int mi_row, mi_col;
+  double fraction_low = 0.0;
+  int low_content_frame = 0;
+  for (mi_row = 0; mi_row < cm->mi_rows; mi_row++)
+    for (mi_col = 0; mi_col < cm->mi_cols; mi_col++) {
+      if (cr->map[mi_row * cm->mi_cols + mi_col] < 1)
+        low_content_frame++;
+    }
+  fraction_low =
+      (double)low_content_frame / (cm->mi_rows * cm->mi_cols);
+  // Update average.
+  cr->low_content_avg = (fraction_low + 3 * cr->low_content_avg) / 4;
+  if (cpi->refresh_golden_frame == 1) {
+    // Don't update golden reference if the amount of low_content for the
+    // current encoded frame is small, or if the recursive average of the
+    // low_content over the update interval window falls below threshold.
+    if (fraction_low < 0.8 || cr->low_content_avg < 0.7)
+      cpi->refresh_golden_frame = 0;
+    // Reset for next internal.
+    cr->low_content_avg = fraction_low;
+  }
+}
+
 // Update the segmentation map, and related quantities: cyclic refresh map,
 // refresh sb_index, and target number of blocks to be refreshed.
 // The map is set to either 0/CR_SEGMENT_ID_BASE (no refresh) or to
@@ -347,6 +389,8 @@ void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) {
   CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
   struct segmentation *const seg = &cm->seg;
   const int apply_cyclic_refresh  = apply_cyclic_refresh_bitrate(cm, rc);
+  if (cm->current_video_frame == 0)
+    cr->low_content_avg = 0.0;
   // Don't apply refresh on key frame or enhancement layer frames.
   if (!apply_cyclic_refresh ||
       (cm->frame_type == KEY_FRAME) ||

vp9/encoder/vp9_aq_cyclicrefresh.h

@@ -62,7 +62,13 @@ void vp9_cyclic_refresh_update_segment(struct VP9_COMP *const cpi,
 void vp9_cyclic_refresh_update__map(struct VP9_COMP *const cpi);
 
 // Update the actual number of blocks that were applied the segment delta q.
-void vp9_cyclic_refresh_update_actual_count(struct VP9_COMP *const cpi);
+void vp9_cyclic_refresh_postencode(struct VP9_COMP *const cpi);
+
+// Set golden frame update interval, for non-svc 1 pass CBR mode.
+void vp9_cyclic_refresh_set_golden_update(struct VP9_COMP *cpi);
+
+// Check if we should not update golden reference, based on past refresh stats.
+void vp9_cyclic_refresh_check_golden_update(struct VP9_COMP *const cpi);
 
 // Set/update global/frame level refresh parameters.
 void vp9_cyclic_refresh_update_parameters(struct VP9_COMP *const cpi);

vp9/encoder/vp9_encoder.c

@@ -2843,6 +2843,14 @@ static void encode_without_recode_loop(VP9_COMP *cpi) {
   // transform / motion compensation build reconstruction frame
   vp9_encode_frame(cpi);
 
+  // Update some stats from cyclic refresh, and check if we should not update
+  // golden reference, for non-SVC 1 pass CBR.
+  if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ &&
+      cm->frame_type != KEY_FRAME &&
+      !cpi->use_svc &&
+      (cpi->oxcf.pass == 0 && cpi->oxcf.rc_mode == VPX_CBR))
+    vp9_cyclic_refresh_check_golden_update(cpi);
+
   // Update the skip mb flag probabilities based on the distribution
   // seen in the last encoder iteration.
   // update_base_skip_probs(cpi);
@@ -3220,7 +3228,6 @@ static void encode_frame_to_data_rate(VP9_COMP *cpi,
   TX_SIZE t;
 
   set_ext_overrides(cpi);
-
   vp9_clear_system_state();
 
   // Set the arf sign bias for this frame.

vp9/encoder/vp9_ratectrl.c

@@ -1229,7 +1229,7 @@ void vp9_rc_postencode_update(VP9_COMP *cpi, uint64_t bytes_used) {
   const int qindex = cm->base_qindex;
 
   if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ && cm->seg.enabled) {
-    vp9_cyclic_refresh_update_actual_count(cpi);
+    vp9_cyclic_refresh_postencode(cpi);
   }
 
   // Update rate control heuristics
@@ -1535,7 +1535,10 @@ void vp9_rc_get_one_pass_cbr_params(VP9_COMP *cpi) {
     cm->frame_type = INTER_FRAME;
   }
   if (rc->frames_till_gf_update_due == 0) {
-    rc->baseline_gf_interval = DEFAULT_GF_INTERVAL;
+    if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ)
+      vp9_cyclic_refresh_set_golden_update(cpi);
+    else
+      rc->baseline_gf_interval = DEFAULT_GF_INTERVAL;
     rc->frames_till_gf_update_due = rc->baseline_gf_interval;
     // NOTE: frames_till_gf_update_due must be <= frames_to_key.
     if (rc->frames_till_gf_update_due > rc->frames_to_key)