libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_aq_cyclicrefresh.c

+/*
+ *  Copyright (c) 2014 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <limits.h>
+#include <math.h>
+
+#include "vp9/encoder/vp9_aq_cyclicrefresh.h"
+
+#include "vp9/common/vp9_seg_common.h"
+
+#include "vp9/encoder/vp9_ratectrl.h"
+#include "vp9/encoder/vp9_rdopt.h"
+#include "vp9/encoder/vp9_segmentation.h"
+
+struct CYCLIC_REFRESH {
+  // Percentage of super-blocks per frame that are targeted as candidates
+  // for cyclic refresh.
+  int max_sbs_perframe;
+  // Maximum q-delta as percentage of base q.
+  int max_qdelta_perc;
+  // Block size below which we don't apply cyclic refresh.
+  BLOCK_SIZE min_block_size;
+  // Superblock starting index for cycling through the frame.
+  int sb_index;
+  // Controls how long a block will need to wait to be refreshed again.
+  int time_for_refresh;
+  // Actual number of (8x8) blocks that were applied delta-q (segment 1).
+  int num_seg_blocks;
+  // Actual encoding bits for segment 1.
+  int actual_seg_bits;
+  // RD mult. parameters for segment 1.
+  int rdmult;
+  // Cyclic refresh map.
+  signed char *map;
+  // Projected rate and distortion for the current superblock.
+  int64_t projected_rate_sb;
+  int64_t projected_dist_sb;
+  // Thresholds applied to projected rate/distortion of the superblock.
+  int64_t thresh_rate_sb;
+  int64_t thresh_dist_sb;
+};
+
+CYCLIC_REFRESH *vp9_cyclic_refresh_alloc(int mi_rows, int mi_cols) {
+  CYCLIC_REFRESH *const cr = vpx_calloc(1, sizeof(*cr));
+  if (cr == NULL)
+    return NULL;
+
+  cr->map = vpx_calloc(mi_rows * mi_cols, sizeof(*cr->map));
+  if (cr->map == NULL) {
+    vpx_free(cr);
+    return NULL;
+  }
+
+  return cr;
+}
+
+void vp9_cyclic_refresh_free(CYCLIC_REFRESH *cr) {
+  vpx_free(cr->map);
+  vpx_free(cr);
+}
+
+// Check if we should turn off cyclic refresh based on bitrate condition.
+static int apply_cyclic_refresh_bitrate(const VP9_COMMON *cm,
+                                        const RATE_CONTROL *rc) {
+  // Turn off cyclic refresh if bits available per frame is not sufficiently
+  // larger than bit cost of segmentation. Segment map bit cost should scale
+  // with number of seg blocks, so compare available bits to number of blocks.
+  // Average bits available per frame = av_per_frame_bandwidth
+  // Number of (8x8) blocks in frame = mi_rows * mi_cols;
+  const float factor  = 0.5;
+  const int number_blocks = cm->mi_rows  * cm->mi_cols;
+  // The condition below corresponds to turning off at target bitrates:
+  // ~24kbps for CIF, 72kbps for VGA (at 30fps).
+  // Also turn off at very small frame sizes, to avoid too large fraction of
+  // superblocks to be refreshed per frame. Threshold below is less than QCIF.
+  if (rc->av_per_frame_bandwidth < factor * number_blocks ||
+      number_blocks / 64 < 5)
+    return 0;
+  else
+    return 1;
+}
+
+// Check if this coding block, of size bsize, should be considered for refresh
+// (lower-qp coding). Decision can be based on various factors, such as
+// size of the coding block (i.e., below min_block size rejected), coding
+// mode, and rate/distortion.
+static int candidate_refresh_aq(const CYCLIC_REFRESH *cr,
+                                const MB_MODE_INFO *mbmi,
+                                BLOCK_SIZE bsize, int use_rd) {
+  if (use_rd) {
+    // If projected rate is below the thresh_rate (well below target,
+    // so undershoot expected), accept it for lower-qp coding.
+    if (cr->projected_rate_sb < cr->thresh_rate_sb)
+      return 1;
+    // Otherwise, reject the block for lower-qp coding if any of the following:
+    // 1) prediction block size is below min_block_size
+    // 2) mode is non-zero mv and projected distortion is above thresh_dist
+    // 3) mode is an intra-mode (we may want to allow some of this under
+    // another thresh_dist)
+    else if (bsize < cr->min_block_size ||
+             (mbmi->mv[0].as_int != 0 &&
+              cr->projected_dist_sb > cr->thresh_dist_sb) ||
+             !is_inter_block(mbmi))
+      return 0;
+    else
+      return 1;
+  } else {
+    // Rate/distortion not used for update.
+    if (bsize < cr->min_block_size ||
+        mbmi->mv[0].as_int != 0 ||
+        !is_inter_block(mbmi))
+      return 0;
+    else
+      return 1;
+  }
+}
+
+// Prior to coding a given prediction block, of size bsize at (mi_row, mi_col),
+// check if we should reset the segment_id, and update the cyclic_refresh map
+// and segmentation map.
+void vp9_cyclic_refresh_update_segment(VP9_COMP *const cpi,
+                                       MB_MODE_INFO *const mbmi,
+                                       int mi_row, int mi_col,
+                                       BLOCK_SIZE bsize, int use_rd) {
+  const VP9_COMMON *const cm = &cpi->common;
+  CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
+  const int bw = num_8x8_blocks_wide_lookup[bsize];
+  const int bh = num_8x8_blocks_high_lookup[bsize];
+  const int xmis = MIN(cm->mi_cols - mi_col, bw);
+  const int ymis = MIN(cm->mi_rows - mi_row, bh);
+  const int block_index = mi_row * cm->mi_cols + mi_col;
+  const int refresh_this_block = candidate_refresh_aq(cr, mbmi, bsize, use_rd);
+  // Default is to not update the refresh map.
+  int new_map_value = cr->map[block_index];
+  int x = 0; int y = 0;
+
+  // Check if we should reset the segment_id for this block.
+  if (mbmi->segment_id > 0 && !refresh_this_block)
+    mbmi->segment_id = 0;
+
+  // Update the cyclic refresh map, to be used for setting segmentation map
+  // for the next frame. If the block  will be refreshed this frame, mark it
+  // as clean. The magnitude of the -ve influences how long before we consider
+  // it for refresh again.
+  if (mbmi->segment_id == 1) {
+    new_map_value = -cr->time_for_refresh;
+  } else if (refresh_this_block) {
+    // Else if it is accepted as candidate for refresh, and has not already
+    // been refreshed (marked as 1) then mark it as a candidate for cleanup
+    // for future time (marked as 0), otherwise don't update it.
+    if (cr->map[block_index] == 1)
+      new_map_value = 0;
+  } else {
+    // Leave it marked as block that is not candidate for refresh.
+    new_map_value = 1;
+  }
+  // Update entries in the cyclic refresh map with new_map_value, and
+  // copy mbmi->segment_id into global segmentation map.
+  for (y = 0; y < ymis; y++)
+    for (x = 0; x < xmis; x++) {
+      cr->map[block_index + y * cm->mi_cols + x] = new_map_value;
+      cpi->segmentation_map[block_index + y * cm->mi_cols + x] =
+          mbmi->segment_id;
+    }
+  // Keep track of actual number (in units of 8x8) of blocks in segment 1 used
+  // for encoding this frame.
+  if (mbmi->segment_id)
+    cr->num_seg_blocks += xmis * ymis;
+}
+
+// Setup cyclic background refresh: set delta q and segmentation map.
+void vp9_cyclic_refresh_setup(VP9_COMP *const cpi) {
+  VP9_COMMON *const cm = &cpi->common;
+  const RATE_CONTROL *const rc = &cpi->rc;
+  CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
+  struct segmentation *const seg = &cm->seg;
+  unsigned char *const seg_map = cpi->segmentation_map;
+  const int apply_cyclic_refresh  = apply_cyclic_refresh_bitrate(cm, rc);
+  // Don't apply refresh on key frame or enhancement layer frames.
+  if (!apply_cyclic_refresh ||
+      (cm->frame_type == KEY_FRAME) ||
+      (cpi->svc.temporal_layer_id > 0)) {
+    // Set segmentation map to 0 and disable.
+    vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
+    vp9_disable_segmentation(&cm->seg);
+    if (cm->frame_type == KEY_FRAME)
+      cr->sb_index = 0;
+    return;
+  } else {
+    int qindex_delta = 0;
+    int i, block_count, bl_index, sb_rows, sb_cols, sbs_in_frame;
+    int xmis, ymis, x, y, qindex2;
+
+    // Rate target ratio to set q delta.
+    const float rate_ratio_qdelta = 2.0;
+    vp9_clear_system_state();
+    // Some of these parameters may be set via codec-control function later.
+    cr->max_sbs_perframe = 10;
+    cr->max_qdelta_perc = 50;
+    cr->min_block_size = BLOCK_8X8;
+    cr->time_for_refresh = 1;
+    // Set rate threshold to some fraction of target (and scaled by 256).
+    cr->thresh_rate_sb = (rc->sb64_target_rate * 256) >> 2;
+    // Distortion threshold, quadratic in Q, scale factor to be adjusted.
+    cr->thresh_dist_sb = 8 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) *
+        vp9_convert_qindex_to_q(cm->base_qindex));
+    if (cpi->sf.use_nonrd_pick_mode) {
+      // May want to be more conservative with thresholds in non-rd mode for now
+      // as rate/distortion are derived from model based on prediction residual.
+      cr->thresh_rate_sb = (rc->sb64_target_rate * 256) >> 3;
+      cr->thresh_dist_sb = 4 * (int)(vp9_convert_qindex_to_q(cm->base_qindex) *
+          vp9_convert_qindex_to_q(cm->base_qindex));
+    }
+
+    cr->num_seg_blocks = 0;
+    // Set up segmentation.
+    // Clear down the segment map.
+    vpx_memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
+    vp9_enable_segmentation(&cm->seg);
+    vp9_clearall_segfeatures(seg);
+    // Select delta coding method.
+    seg->abs_delta = SEGMENT_DELTADATA;
+
+    // Note: setting temporal_update has no effect, as the seg-map coding method
+    // (temporal or spatial) is determined in vp9_choose_segmap_coding_method(),
+    // based on the coding cost of each method. For error_resilient mode on the
+    // last_frame_seg_map is set to 0, so if temporal coding is used, it is
+    // relative to 0 previous map.
+    // seg->temporal_update = 0;
+
+    // Segment 0 "Q" feature is disabled so it defaults to the baseline Q.
+    vp9_disable_segfeature(seg, 0, SEG_LVL_ALT_Q);
+    // Use segment 1 for in-frame Q adjustment.
+    vp9_enable_segfeature(seg, 1, SEG_LVL_ALT_Q);
+
+    // Set the q delta for segment 1.
+    qindex_delta = vp9_compute_qdelta_by_rate(rc, cm->frame_type,
+                                              cm->base_qindex,
+                                              rate_ratio_qdelta);
+    // TODO(marpan): Incorporate the actual-vs-target rate over/undershoot from
+    // previous encoded frame.
+    if (-qindex_delta > cr->max_qdelta_perc * cm->base_qindex / 100)
+      qindex_delta = -cr->max_qdelta_perc * cm->base_qindex / 100;
+
+    // Compute rd-mult for segment 1.
+    qindex2 = clamp(cm->base_qindex + cm->y_dc_delta_q + qindex_delta, 0, MAXQ);
+    cr->rdmult = vp9_compute_rd_mult(cpi, qindex2);
+
+    vp9_set_segdata(seg, 1, SEG_LVL_ALT_Q, qindex_delta);
+
+    sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
+    sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
+    sbs_in_frame = sb_cols * sb_rows;
+    // Number of target superblocks to get the q delta (segment 1).
+    block_count = cr->max_sbs_perframe * sbs_in_frame / 100;
+    // Set the segmentation map: cycle through the superblocks, starting at
+    // cr->mb_index, and stopping when either block_count blocks have been found
+    // to be refreshed, or we have passed through whole frame.
+    assert(cr->sb_index < sbs_in_frame);
+    i = cr->sb_index;
+    do {
+      int sum_map = 0;
+      // Get the mi_row/mi_col corresponding to superblock index i.
+      int sb_row_index = (i / sb_cols);
+      int sb_col_index = i - sb_row_index * sb_cols;
+      int mi_row = sb_row_index * MI_BLOCK_SIZE;
+      int mi_col = sb_col_index * MI_BLOCK_SIZE;
+      assert(mi_row >= 0 && mi_row < cm->mi_rows);
+      assert(mi_col >= 0 && mi_col < cm->mi_cols);
+      bl_index = mi_row * cm->mi_cols + mi_col;
+      // Loop through all 8x8 blocks in superblock and update map.
+      xmis = MIN(cm->mi_cols - mi_col,
+                 num_8x8_blocks_wide_lookup[BLOCK_64X64]);
+      ymis = MIN(cm->mi_rows - mi_row,
+                 num_8x8_blocks_high_lookup[BLOCK_64X64]);
+      for (y = 0; y < ymis; y++) {
+        for (x = 0; x < xmis; x++) {
+          const int bl_index2 = bl_index + y * cm->mi_cols + x;
+          // If the block is as a candidate for clean up then mark it
+          // for possible boost/refresh (segment 1). The segment id may get
+          // reset to 0 later if block gets coded anything other than ZEROMV.
+          if (cr->map[bl_index2] == 0) {
+            seg_map[bl_index2] = 1;
+            sum_map++;
+          } else if (cr->map[bl_index2] < 0) {
+            cr->map[bl_index2]++;
+          }
+        }
+      }
+      // Enforce constant segment over superblock.
+      // If segment is partial over superblock, reset to either all 1 or 0.
+      if (sum_map > 0 && sum_map < xmis * ymis) {
+        const int new_value = (sum_map >= xmis * ymis / 2);
+        for (y = 0; y < ymis; y++)
+          for (x = 0; x < xmis; x++)
+            seg_map[bl_index + y * cm->mi_cols + x] = new_value;
+      }
+      i++;
+      if (i == sbs_in_frame) {
+        i = 0;
+      }
+      if (sum_map >= xmis * ymis /2)
+        block_count--;
+    } while (block_count && i != cr->sb_index);
+    cr->sb_index = i;
+  }
+}
+
+void vp9_cyclic_refresh_set_rate_and_dist_sb(CYCLIC_REFRESH *cr,
+                                             int64_t rate_sb, int64_t dist_sb) {
+  cr->projected_rate_sb = rate_sb;
+  cr->projected_dist_sb = dist_sb;
+}
+
+int vp9_cyclic_refresh_get_rdmult(const CYCLIC_REFRESH *cr) {
+  return cr->rdmult;
+}