Experiment to adapt for net AQ offset.

In Aq mode 1 the segment and AQ delta for each block is based
on spatial variance. There may be a net imbalance between blocks
that have lower Q than the baseline value and those that have higher Q.

This patch monitors that imbalance and extends the allowed baseline
Q range for the frame to accommodate adjustment of that baseline value
to compensate.

Change-Id: Iae8a48c7c01fe2af94a141e149d03acf467237ca

vp9/common/vp9_seg_common.c

@@ -28,6 +28,7 @@ static const int seg_feature_data_max[SEG_LVL_MAX] = {
 void vp9_clearall_segfeatures(struct segmentation *seg) {
   vp9_zero(seg->feature_data);
   vp9_zero(seg->feature_mask);
+  seg->aq_av_offset = 0;
 }
 
 void vp9_enable_segfeature(struct segmentation *seg, int segment_id,

vp9/common/vp9_seg_common.h

@@ -47,6 +47,7 @@ struct segmentation {
 
   int16_t feature_data[MAX_SEGMENTS][SEG_LVL_MAX];
   unsigned int feature_mask[MAX_SEGMENTS];
+  int aq_av_offset;
 };
 
 static INLINE int segfeature_active(const struct segmentation *seg,

vp9/encoder/vp9_encodeframe.c

@@ -4137,6 +4137,31 @@ static INTERP_FILTER get_interp_filter(
   }
 }
 
+static int compute_frame_aq_offset(struct VP9_COMP *cpi) {
+  VP9_COMMON *const cm = &cpi->common;
+  MODE_INFO **mi_8x8_ptr = cm->mi_grid_visible;
+  struct segmentation *const seg = &cm->seg;
+
+  int mi_row, mi_col;
+  int sum_delta = 0;
+  int map_index = 0;
+  int qdelta_index;
+  int segment_id;
+
+  for (mi_row = 0; mi_row < cm->mi_rows; mi_row++) {
+    MODE_INFO **mi_8x8 = mi_8x8_ptr;
+    for (mi_col = 0; mi_col < cm->mi_cols; mi_col++, mi_8x8++) {
+      segment_id = mi_8x8[0]->segment_id;
+      qdelta_index = get_segdata(seg, segment_id, SEG_LVL_ALT_Q);
+      sum_delta += qdelta_index;
+      map_index++;
+    }
+    mi_8x8_ptr += cm->mi_stride;
+  }
+
+  return sum_delta / (cm->mi_rows * cm->mi_cols);
+}
+
 void vp9_encode_frame(VP9_COMP *cpi) {
   VP9_COMMON *const cm = &cpi->common;
 
@@ -4259,8 +4284,13 @@ void vp9_encode_frame(VP9_COMP *cpi) {
     cm->reference_mode = SINGLE_REFERENCE;
     encode_frame_internal(cpi);
   }
-}
 
+  // If segmentated AQ is enabled compute the average AQ weighting.
+  if (cm->seg.enabled && (cpi->oxcf.aq_mode != NO_AQ) &&
+      (cm->seg.update_map || cm->seg.update_data)) {
+    cm->seg.aq_av_offset = compute_frame_aq_offset(cpi);
+  }
+}
 static void sum_intra_stats(FRAME_COUNTS *counts, const MODE_INFO *mi) {
   const PREDICTION_MODE y_mode = mi->mode;
   const PREDICTION_MODE uv_mode = mi->uv_mode;

vp9/encoder/vp9_encoder.c

@@ -3137,7 +3137,7 @@ static void output_frame_level_debug_stats(VP9_COMP *cpi) {
        "%7.2lf %7.2lf %7.2lf %7.2lf %7.2lf"
         "%6d %6d %5d %5d %5d "
         "%10"PRId64" %10.3lf"
-        "%10lf %8u %10"PRId64" %10d %10d %10d %10d\n",
+        "%10lf %8u %10"PRId64" %10d %10d %10d %10d %10d\n",
         cpi->common.current_video_frame,
         cm->width, cm->height,
         cpi->td.rd_counts.m_search_count,
@@ -3171,7 +3171,8 @@ static void output_frame_level_debug_stats(VP9_COMP *cpi) {
         cpi->tot_recode_hits, recon_err, cpi->rc.kf_boost,
         cpi->twopass.kf_zeromotion_pct,
         cpi->twopass.fr_content_type,
-        cm->lf.filter_level);
+        cm->lf.filter_level,
+        cm->seg.aq_av_offset);
   }
   fclose(f);
 

vp9/encoder/vp9_firstpass.c

@@ -2849,6 +2849,7 @@ void vp9_rc_get_second_pass_params(VP9_COMP *cpi) {
 void vp9_twopass_postencode_update(VP9_COMP *cpi) {
   TWO_PASS *const twopass = &cpi->twopass;
   RATE_CONTROL *const rc = &cpi->rc;
+  VP9_COMMON *const cm = &cpi->common;
   const int bits_used = rc->base_frame_target;
 
   // VBR correction is done through rc->vbr_bits_off_target. Based on the
@@ -2886,6 +2887,22 @@ void vp9_twopass_postencode_update(VP9_COMP *cpi) {
       rc->worst_quality - twopass->active_worst_quality;
     const int minq_adj_limit =
         (cpi->oxcf.rc_mode == VPX_CQ ? MINQ_ADJ_LIMIT_CQ : MINQ_ADJ_LIMIT);
+    int aq_extend_min = 0;
+    int aq_extend_max = 0;
+
+    // Extend min or Max Q range to account for imbalance from the base
+    // value when using AQ.
+    if (cpi->oxcf.aq_mode != NO_AQ) {
+      if (cm->seg.aq_av_offset < 0) {
+        // The balance of the AQ map tends towarda lowering the average Q.
+        aq_extend_min = 0;
+        aq_extend_max = VPXMIN(maxq_adj_limit, -cm->seg.aq_av_offset);
+      } else {
+        // The balance of the AQ map tends towards raising the average Q.
+        aq_extend_min = VPXMIN(minq_adj_limit, cm->seg.aq_av_offset);
+        aq_extend_max = 0;
+      }
+    }
 
     // Undershoot.
     if (rc->rate_error_estimate > cpi->oxcf.under_shoot_pct) {
@@ -2910,8 +2927,10 @@ void vp9_twopass_postencode_update(VP9_COMP *cpi) {
         --twopass->extend_maxq;
     }
 
-    twopass->extend_minq = clamp(twopass->extend_minq, 0, minq_adj_limit);
-    twopass->extend_maxq = clamp(twopass->extend_maxq, 0, maxq_adj_limit);
+    twopass->extend_minq =
+        clamp(twopass->extend_minq, aq_extend_min, minq_adj_limit);
+    twopass->extend_maxq =
+        clamp(twopass->extend_maxq, aq_extend_max, maxq_adj_limit);
 
     // If there is a big and undexpected undershoot then feed the extra
     // bits back in quickly. One situation where this may happen is if a