text: /*
   *  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 <assert.h>
  #include <limits.h>
  #include <math.h>
  #include <stdio.h>
  
  #include "./vp9_rtcd.h"
  #include "./vpx_dsp_rtcd.h"
  
  #include "vpx/vpx_codec.h"
  #include "vpx_dsp/vpx_dsp_common.h"
  #include "vpx_mem/vpx_mem.h"
  #include "vpx_ports/mem.h"
  
  #include "vp9/common/vp9_blockd.h"
  #include "vp9/common/vp9_common.h"
  #include "vp9/common/vp9_mvref_common.h"
  #include "vp9/common/vp9_pred_common.h"
  #include "vp9/common/vp9_reconinter.h"
  #include "vp9/common/vp9_reconintra.h"
  #include "vp9/common/vp9_scan.h"
  
  #include "vp9/encoder/vp9_cost.h"
  #include "vp9/encoder/vp9_encoder.h"
  #include "vp9/encoder/vp9_pickmode.h"
  #include "vp9/encoder/vp9_ratectrl.h"
  #include "vp9/encoder/vp9_rd.h"
  
  typedef struct {
    uint8_t *data;
    int stride;
    int in_use;
  } PRED_BUFFER;
  
  static const int pos_shift_16x16[4][4] = {
    { 9, 10, 13, 14 }, { 11, 12, 15, 16 }, { 17, 18, 21, 22 }, { 19, 20, 23, 24 }
  };
  
  static int mv_refs_rt(VP9_COMP *cpi, const VP9_COMMON *cm, const MACROBLOCK *x,
                        const MACROBLOCKD *xd, const TileInfo *const tile,
                        MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
                        int_mv *mv_ref_list, int_mv *base_mv, int mi_row,
                        int mi_col, int use_base_mv) {
    const int *ref_sign_bias = cm->ref_frame_sign_bias;
    int i, refmv_count = 0;
  
    const POSITION *const mv_ref_search = mv_ref_blocks[mi->sb_type];
  
    int different_ref_found = 0;
    int context_counter = 0;
    int const_motion = 0;
  
    // Blank the reference vector list
    memset(mv_ref_list, 0, sizeof(*mv_ref_list) * MAX_MV_REF_CANDIDATES);
  
    // The nearest 2 blocks are treated differently
    // if the size < 8x8 we get the mv from the bmi substructure,
    // and we also need to keep a mode count.
    for (i = 0; i < 2; ++i) {
      const POSITION *const mv_ref = &mv_ref_search[i];
      if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
        const MODE_INFO *const candidate_mi =
            xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
        // Keep counts for entropy encoding.
        context_counter += mode_2_counter[candidate_mi->mode];
        different_ref_found = 1;
  
        if (candidate_mi->ref_frame[0] == ref_frame)
          ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 0, mv_ref->col, -1),
                          refmv_count, mv_ref_list, Done);
      }
    }
  
    const_motion = 1;
  
    // Check the rest of the neighbors in much the same way
    // as before except we don't need to keep track of sub blocks or
    // mode counts.
    for (; i < MVREF_NEIGHBOURS && !refmv_count; ++i) {
      const POSITION *const mv_ref = &mv_ref_search[i];
      if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
        const MODE_INFO *const candidate_mi =
            xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
        different_ref_found = 1;
  
        if (candidate_mi->ref_frame[0] == ref_frame)
          ADD_MV_REF_LIST(candidate_mi->mv[0], refmv_count, mv_ref_list, Done);
      }
    }
  
    // Since we couldn't find 2 mvs from the same reference frame
    // go back through the neighbors and find motion vectors from
    // different reference frames.
    if (different_ref_found && !refmv_count) {
      for (i = 0; i < MVREF_NEIGHBOURS; ++i) {
        const POSITION *mv_ref = &mv_ref_search[i];
        if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
          const MODE_INFO *const candidate_mi =
              xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
  
          // If the candidate is INTRA we don't want to consider its mv.
          IF_DIFF_REF_FRAME_ADD_MV(candidate_mi, ref_frame, ref_sign_bias,
                                   refmv_count, mv_ref_list, Done);
        }
      }
    }
    if (use_base_mv &&
        !cpi->svc.layer_context[cpi->svc.temporal_layer_id].is_key_frame &&
        ref_frame == LAST_FRAME) {
      // Get base layer mv.
      MV_REF *candidate =
          &cm->prev_frame
               ->mvs[(mi_col >> 1) + (mi_row >> 1) * (cm->mi_cols >> 1)];
      if (candidate->mv[0].as_int != INVALID_MV) {
        base_mv->as_mv.row = (candidate->mv[0].as_mv.row * 2);
        base_mv->as_mv.col = (candidate->mv[0].as_mv.col * 2);
        clamp_mv_ref(&base_mv->as_mv, xd);
      } else {
        base_mv->as_int = INVALID_MV;
      }
    }
  
  Done:
  
    x->mbmi_ext->mode_context[ref_frame] = counter_to_context[context_counter];
  
    // Clamp vectors
    for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i)
      clamp_mv_ref(&mv_ref_list[i].as_mv, xd);
  
    return const_motion;
  }
  
  static int combined_motion_search(VP9_COMP *cpi, MACROBLOCK *x,
                                    BLOCK_SIZE bsize, int mi_row, int mi_col,
                                    int_mv *tmp_mv, int *rate_mv,
                                    int64_t best_rd_sofar, int use_base_mv) {
    MACROBLOCKD *xd = &x->e_mbd;
    MODE_INFO *mi = xd->mi[0];
    struct buf_2d backup_yv12[MAX_MB_PLANE] = { { 0, 0 } };
    const int step_param = cpi->sf.mv.fullpel_search_step_param;
    const int sadpb = x->sadperbit16;
    MV mvp_full;
    const int ref = mi->ref_frame[0];
    const MV ref_mv = x->mbmi_ext->ref_mvs[ref][0].as_mv;
    MV center_mv;
    uint32_t dis;
    int rate_mode;
    const MvLimits tmp_mv_limits = x->mv_limits;
    int rv = 0;
    int cost_list[5];
    int search_subpel = 1;
    const YV12_BUFFER_CONFIG *scaled_ref_frame =
        vp9_get_scaled_ref_frame(cpi, ref);
    if (scaled_ref_frame) {
      int i;
      // Swap out the reference frame for a version that's been scaled to
      // match the resolution of the current frame, allowing the existing
      // motion search code to be used without additional modifications.
      for (i = 0; i < MAX_MB_PLANE; i++) backup_yv12[i] = xd->plane[i].pre[0];
      vp9_setup_pre_planes(xd, 0, scaled_ref_frame, mi_row, mi_col, NULL);
    }
    vp9_set_mv_search_range(&x->mv_limits, &ref_mv);
  
    // Limit motion vector for large lightning change.
    if (cpi->oxcf.speed > 5 && x->lowvar_highsumdiff) {
      x->mv_limits.col_min = VPXMAX(x->mv_limits.col_min, -10);
      x->mv_limits.row_min = VPXMAX(x->mv_limits.row_min, -10);
      x->mv_limits.col_max = VPXMIN(x->mv_limits.col_max, 10);
      x->mv_limits.row_max = VPXMIN(x->mv_limits.row_max, 10);
    }
  
    assert(x->mv_best_ref_index[ref] <= 2);
    if (x->mv_best_ref_index[ref] < 2)
      mvp_full = x->mbmi_ext->ref_mvs[ref][x->mv_best_ref_index[ref]].as_mv;
    else
      mvp_full = x->pred_mv[ref];
  
    mvp_full.col >>= 3;
    mvp_full.row >>= 3;
  
    if (!use_base_mv)
      center_mv = ref_mv;
    else
      center_mv = tmp_mv->as_mv;
  
    if (x->sb_use_mv_part) {
      tmp_mv->as_mv.row = x->sb_mvrow_part >> 3;
      tmp_mv->as_mv.col = x->sb_mvcol_part >> 3;
    } else {
      vp9_full_pixel_search(
          cpi, x, bsize, &mvp_full, step_param, cpi->sf.mv.search_method, sadpb,
          cond_cost_list(cpi, cost_list), &center_mv, &tmp_mv->as_mv, INT_MAX, 0);
    }
  
    x->mv_limits = tmp_mv_limits;
  
    // calculate the bit cost on motion vector
    mvp_full.row = tmp_mv->as_mv.row * 8;
    mvp_full.col = tmp_mv->as_mv.col * 8;
  
    *rate_mv = vp9_mv_bit_cost(&mvp_full, &ref_mv, x->nmvjointcost, x->mvcost,
                               MV_COST_WEIGHT);
  
    rate_mode =
        cpi->inter_mode_cost[x->mbmi_ext->mode_context[ref]][INTER_OFFSET(NEWMV)];
    rv =
        !(RDCOST(x->rdmult, x->rddiv, (*rate_mv + rate_mode), 0) > best_rd_sofar);
  
    // For SVC on non-reference frame, avoid subpel for (0, 0) motion.
    if (cpi->use_svc && cpi->svc.non_reference_frame) {
      if (mvp_full.row == 0 && mvp_full.col == 0) search_subpel = 0;
    }
  
    if (rv && search_subpel) {
      int subpel_force_stop = cpi->sf.mv.subpel_force_stop;
      if (use_base_mv && cpi->sf.base_mv_aggressive) subpel_force_stop = 2;
      if (cpi->sf.mv.enable_adaptive_subpel_force_stop) {
        int mv_thresh = cpi->sf.mv.adapt_subpel_force_stop.mv_thresh;
        if (abs(tmp_mv->as_mv.row) >= mv_thresh ||
            abs(tmp_mv->as_mv.col) >= mv_thresh)
          subpel_force_stop = cpi->sf.mv.adapt_subpel_force_stop.force_stop_above;
        else
          subpel_force_stop = cpi->sf.mv.adapt_subpel_force_stop.force_stop_below;
      }
      cpi->find_fractional_mv_step(
          x, &tmp_mv->as_mv, &ref_mv, cpi->common.allow_high_precision_mv,
          x->errorperbit, &cpi->fn_ptr[bsize], subpel_force_stop,
          cpi->sf.mv.subpel_iters_per_step, cond_cost_list(cpi, cost_list),
          x->nmvjointcost, x->mvcost, &dis, &x->pred_sse[ref], NULL, 0, 0);
      *rate_mv = vp9_mv_bit_cost(&tmp_mv->as_mv, &ref_mv, x->nmvjointcost,
                                 x->mvcost, MV_COST_WEIGHT);
    }
  
    if (scaled_ref_frame) {
      int i;
      for (i = 0; i < MAX_MB_PLANE; i++) xd->plane[i].pre[0] = backup_yv12[i];
    }
    return rv;
  }
  
  static void block_variance(const uint8_t *src, int src_stride,
                             const uint8_t *ref, int ref_stride, int w, int h,
                             unsigned int *sse, int *sum, int block_size,
  #if CONFIG_VP9_HIGHBITDEPTH
                             int use_highbitdepth, vpx_bit_depth_t bd,
  #endif
                             uint32_t *sse8x8, int *sum8x8, uint32_t *var8x8) {
    int i, j, k = 0;
  
    *sse = 0;
    *sum = 0;
  
    for (i = 0; i < h; i += block_size) {
      for (j = 0; j < w; j += block_size) {
  #if CONFIG_VP9_HIGHBITDEPTH
        if (use_highbitdepth) {
          switch (bd) {
            case VPX_BITS_8:
              vpx_highbd_8_get8x8var(src + src_stride * i + j, src_stride,
                                     ref + ref_stride * i + j, ref_stride,
                                     &sse8x8[k], &sum8x8[k]);
              break;
            case VPX_BITS_10:
              vpx_highbd_10_get8x8var(src + src_stride * i + j, src_stride,
                                      ref + ref_stride * i + j, ref_stride,
                                      &sse8x8[k], &sum8x8[k]);
              break;
            case VPX_BITS_12:
              vpx_highbd_12_get8x8var(src + src_stride * i + j, src_stride,
                                      ref + ref_stride * i + j, ref_stride,
                                      &sse8x8[k], &sum8x8[k]);
              break;
          }
        } else {
          vpx_get8x8var(src + src_stride * i + j, src_stride,
                        ref + ref_stride * i + j, ref_stride, &sse8x8[k],
                        &sum8x8[k]);
        }
  #else
        vpx_get8x8var(src + src_stride * i + j, src_stride,
                      ref + ref_stride * i + j, ref_stride, &sse8x8[k],
                      &sum8x8[k]);
  #endif
        *sse += sse8x8[k];
        *sum += sum8x8[k];
        var8x8[k] = sse8x8[k] - (uint32_t)(((int64_t)sum8x8[k] * sum8x8[k]) >> 6);
        k++;
      }
    }
  }
  
  static void calculate_variance(int bw, int bh, TX_SIZE tx_size,
                                 unsigned int *sse_i, int *sum_i,
                                 unsigned int *var_o, unsigned int *sse_o,
                                 int *sum_o) {
    const BLOCK_SIZE unit_size = txsize_to_bsize[tx_size];
    const int nw = 1 << (bw - b_width_log2_lookup[unit_size]);
    const int nh = 1 << (bh - b_height_log2_lookup[unit_size]);
    int i, j, k = 0;
  
    for (i = 0; i < nh; i += 2) {
      for (j = 0; j < nw; j += 2) {
        sse_o[k] = sse_i[i * nw + j] + sse_i[i * nw + j + 1] +
                   sse_i[(i + 1) * nw + j] + sse_i[(i + 1) * nw + j + 1];
        sum_o[k] = sum_i[i * nw + j] + sum_i[i * nw + j + 1] +
                   sum_i[(i + 1) * nw + j] + sum_i[(i + 1) * nw + j + 1];
        var_o[k] = sse_o[k] - (uint32_t)(((int64_t)sum_o[k] * sum_o[k]) >>
                                         (b_width_log2_lookup[unit_size] +
                                          b_height_log2_lookup[unit_size] + 6));
        k++;
      }
    }
  }
  
  // Adjust the ac_thr according to speed, width, height and normalized sum
  static int ac_thr_factor(const int speed, const int width, const int height,
                           const int norm_sum) {
    if (speed >= 8 && norm_sum < 5) {
      if (width <= 640 && height <= 480)
        return 4;
      else
        return 2;
    }
    return 1;
  }
  
  static void model_rd_for_sb_y_large(VP9_COMP *cpi, BLOCK_SIZE bsize,
                                      MACROBLOCK *x, MACROBLOCKD *xd,
                                      int *out_rate_sum, int64_t *out_dist_sum,
                                      unsigned int *var_y, unsigned int *sse_y,
                                      int mi_row, int mi_col, int *early_term,
                                      int *flag_preduv_computed) {
    // Note our transform coeffs are 8 times an orthogonal transform.
    // Hence quantizer step is also 8 times. To get effective quantizer
    // we need to divide by 8 before sending to modeling function.
    unsigned int sse;
    int rate;
    int64_t dist;
    struct macroblock_plane *const p = &x->plane[0];
    struct macroblockd_plane *const pd = &xd->plane[0];
    const uint32_t dc_quant = pd->dequant[0];
    const uint32_t ac_quant = pd->dequant[1];
    const int64_t dc_thr = dc_quant * dc_quant >> 6;
    int64_t ac_thr = ac_quant * ac_quant >> 6;
    unsigned int var;
    int sum;
    int skip_dc = 0;
  
    const int bw = b_width_log2_lookup[bsize];
    const int bh = b_height_log2_lookup[bsize];
    const int num8x8 = 1 << (bw + bh - 2);
    unsigned int sse8x8[64] = { 0 };
    int sum8x8[64] = { 0 };
    unsigned int var8x8[64] = { 0 };
    TX_SIZE tx_size;
    int i, k;
  #if CONFIG_VP9_HIGHBITDEPTH
    const vpx_bit_depth_t bd = cpi->common.bit_depth;
  #endif
    // Calculate variance for whole partition, and also save 8x8 blocks' variance
    // to be used in following transform skipping test.
    block_variance(p->src.buf, p->src.stride, pd->dst.buf, pd->dst.stride,
                   4 << bw, 4 << bh, &sse, &sum, 8,
  #if CONFIG_VP9_HIGHBITDEPTH
                   cpi->common.use_highbitdepth, bd,
  #endif
                   sse8x8, sum8x8, var8x8);
    var = sse - (unsigned int)(((int64_t)sum * sum) >> (bw + bh + 4));
  
    *var_y = var;
    *sse_y = sse;
  
  #if CONFIG_VP9_TEMPORAL_DENOISING
    if (cpi->oxcf.noise_sensitivity > 0 && denoise_svc(cpi) &&
        cpi->oxcf.speed > 5)
      ac_thr = vp9_scale_acskip_thresh(ac_thr, cpi->denoiser.denoising_level,
                                       (abs(sum) >> (bw + bh)),
                                       cpi->svc.temporal_layer_id);
    else
      ac_thr *= ac_thr_factor(cpi->oxcf.speed, cpi->common.width,
                              cpi->common.height, abs(sum) >> (bw + bh));
  #else
    ac_thr *= ac_thr_factor(cpi->oxcf.speed, cpi->common.width,
                            cpi->common.height, abs(sum) >> (bw + bh));
  #endif
  
    if (cpi->common.tx_mode == TX_MODE_SELECT) {
      if (sse > (var << 2))
        tx_size = VPXMIN(max_txsize_lookup[bsize],
                         tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
      else
        tx_size = TX_8X8;
  
      if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ &&
          cyclic_refresh_segment_id_boosted(xd->mi[0]->segment_id))
        tx_size = TX_8X8;
      else if (tx_size > TX_16X16)
        tx_size = TX_16X16;
    } else {
      tx_size = VPXMIN(max_txsize_lookup[bsize],
                       tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
    }
  
    assert(tx_size >= TX_8X8);
    xd->mi[0]->tx_size = tx_size;
  
    // Evaluate if the partition block is a skippable block in Y plane.
    {
      unsigned int sse16x16[16] = { 0 };
      int sum16x16[16] = { 0 };
      unsigned int var16x16[16] = { 0 };
      const int num16x16 = num8x8 >> 2;
  
      unsigned int sse32x32[4] = { 0 };
      int sum32x32[4] = { 0 };
      unsigned int var32x32[4] = { 0 };
      const int num32x32 = num8x8 >> 4;
  
      int ac_test = 1;
      int dc_test = 1;
      const int num = (tx_size == TX_8X8)
                          ? num8x8
                          : ((tx_size == TX_16X16) ? num16x16 : num32x32);
      const unsigned int *sse_tx =
          (tx_size == TX_8X8) ? sse8x8
                              : ((tx_size == TX_16X16) ? sse16x16 : sse32x32);
      const unsigned int *var_tx =
          (tx_size == TX_8X8) ? var8x8
                              : ((tx_size == TX_16X16) ? var16x16 : var32x32);
  
      // Calculate variance if tx_size > TX_8X8
      if (tx_size >= TX_16X16)
        calculate_variance(bw, bh, TX_8X8, sse8x8, sum8x8, var16x16, sse16x16,
                           sum16x16);
      if (tx_size == TX_32X32)
        calculate_variance(bw, bh, TX_16X16, sse16x16, sum16x16, var32x32,
                           sse32x32, sum32x32);
  
      // Skipping test
      x->skip_txfm[0] = SKIP_TXFM_NONE;
      for (k = 0; k < num; k++)
        // Check if all ac coefficients can be quantized to zero.
        if (!(var_tx[k] < ac_thr || var == 0)) {
          ac_test = 0;
          break;
        }
  
      for (k = 0; k < num; k++)
        // Check if dc coefficient can be quantized to zero.
        if (!(sse_tx[k] - var_tx[k] < dc_thr || sse == var)) {
          dc_test = 0;
          break;
        }
  
      if (ac_test) {
        x->skip_txfm[0] = SKIP_TXFM_AC_ONLY;
  
        if (dc_test) x->skip_txfm[0] = SKIP_TXFM_AC_DC;
      } else if (dc_test) {
        skip_dc = 1;
      }
    }
  
    if (x->skip_txfm[0] == SKIP_TXFM_AC_DC) {
      int skip_uv[2] = { 0 };
      unsigned int var_uv[2];
      unsigned int sse_uv[2];
  
      *out_rate_sum = 0;
      *out_dist_sum = sse << 4;
  
      // Transform skipping test in UV planes.
      for (i = 1; i <= 2; i++) {
        if (cpi->oxcf.speed < 8 || x->color_sensitivity[i - 1]) {
          struct macroblock_plane *const p = &x->plane[i];
          struct macroblockd_plane *const pd = &xd->plane[i];
          const TX_SIZE uv_tx_size = get_uv_tx_size(xd->mi[0], pd);
          const BLOCK_SIZE unit_size = txsize_to_bsize[uv_tx_size];
          const BLOCK_SIZE uv_bsize = get_plane_block_size(bsize, pd);
          const int uv_bw = b_width_log2_lookup[uv_bsize];
          const int uv_bh = b_height_log2_lookup[uv_bsize];
          const int sf = (uv_bw - b_width_log2_lookup[unit_size]) +
                         (uv_bh - b_height_log2_lookup[unit_size]);
          const uint32_t uv_dc_thr = pd->dequant[0] * pd->dequant[0] >> (6 - sf);
          const uint32_t uv_ac_thr = pd->dequant[1] * pd->dequant[1] >> (6 - sf);
          int j = i - 1;
  
          vp9_build_inter_predictors_sbp(xd, mi_row, mi_col, bsize, i);
          flag_preduv_computed[i - 1] = 1;
          var_uv[j] = cpi->fn_ptr[uv_bsize].vf(
              p->src.buf, p->src.stride, pd->dst.buf, pd->dst.stride, &sse_uv[j]);
  
          if ((var_uv[j] < uv_ac_thr || var_uv[j] == 0) &&
              (sse_uv[j] - var_uv[j] < uv_dc_thr || sse_uv[j] == var_uv[j]))
            skip_uv[j] = 1;
          else
            break;
        } else {
          skip_uv[i - 1] = 1;
        }
      }
  
      // If the transform in YUV planes are skippable, the mode search checks
      // fewer inter modes and doesn't check intra modes.
      if (skip_uv[0] & skip_uv[1]) {
        *early_term = 1;
      }
      return;
    }
  
    if (!skip_dc) {
  #if CONFIG_VP9_HIGHBITDEPTH
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bsize],
                                   dc_quant >> (xd->bd - 5), &rate, &dist);
  #else
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bsize],
                                   dc_quant >> 3, &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
    }
  
    if (!skip_dc) {
      *out_rate_sum = rate >> 1;
      *out_dist_sum = dist << 3;
    } else {
      *out_rate_sum = 0;
      *out_dist_sum = (sse - var) << 4;
    }
  
  #if CONFIG_VP9_HIGHBITDEPTH
    vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bsize],
                                 ac_quant >> (xd->bd - 5), &rate, &dist);
  #else
    vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bsize], ac_quant >> 3,
                                 &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
  
    *out_rate_sum += rate;
    *out_dist_sum += dist << 4;
  }
  
  static void model_rd_for_sb_y(VP9_COMP *cpi, BLOCK_SIZE bsize, MACROBLOCK *x,
                                MACROBLOCKD *xd, int *out_rate_sum,
                                int64_t *out_dist_sum, unsigned int *var_y,
                                unsigned int *sse_y) {
    // Note our transform coeffs are 8 times an orthogonal transform.
    // Hence quantizer step is also 8 times. To get effective quantizer
    // we need to divide by 8 before sending to modeling function.
    unsigned int sse;
    int rate;
    int64_t dist;
    struct macroblock_plane *const p = &x->plane[0];
    struct macroblockd_plane *const pd = &xd->plane[0];
    const int64_t dc_thr = p->quant_thred[0] >> 6;
    const int64_t ac_thr = p->quant_thred[1] >> 6;
    const uint32_t dc_quant = pd->dequant[0];
    const uint32_t ac_quant = pd->dequant[1];
    unsigned int var = cpi->fn_ptr[bsize].vf(p->src.buf, p->src.stride,
                                             pd->dst.buf, pd->dst.stride, &sse);
    int skip_dc = 0;
  
    *var_y = var;
    *sse_y = sse;
  
    if (cpi->common.tx_mode == TX_MODE_SELECT) {
      if (sse > (var << 2))
        xd->mi[0]->tx_size =
            VPXMIN(max_txsize_lookup[bsize],
                   tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
      else
        xd->mi[0]->tx_size = TX_8X8;
  
      if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ &&
          cyclic_refresh_segment_id_boosted(xd->mi[0]->segment_id))
        xd->mi[0]->tx_size = TX_8X8;
      else if (xd->mi[0]->tx_size > TX_16X16)
        xd->mi[0]->tx_size = TX_16X16;
    } else {
      xd->mi[0]->tx_size =
          VPXMIN(max_txsize_lookup[bsize],
                 tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
    }
  
    // Evaluate if the partition block is a skippable block in Y plane.
    {
      const BLOCK_SIZE unit_size = txsize_to_bsize[xd->mi[0]->tx_size];
      const unsigned int num_blk_log2 =
          (b_width_log2_lookup[bsize] - b_width_log2_lookup[unit_size]) +
          (b_height_log2_lookup[bsize] - b_height_log2_lookup[unit_size]);
      const unsigned int sse_tx = sse >> num_blk_log2;
      const unsigned int var_tx = var >> num_blk_log2;
  
      x->skip_txfm[0] = SKIP_TXFM_NONE;
      // Check if all ac coefficients can be quantized to zero.
      if (var_tx < ac_thr || var == 0) {
        x->skip_txfm[0] = SKIP_TXFM_AC_ONLY;
        // Check if dc coefficient can be quantized to zero.
        if (sse_tx - var_tx < dc_thr || sse == var)
          x->skip_txfm[0] = SKIP_TXFM_AC_DC;
      } else {
        if (sse_tx - var_tx < dc_thr || sse == var) skip_dc = 1;
      }
    }
  
    if (x->skip_txfm[0] == SKIP_TXFM_AC_DC) {
      *out_rate_sum = 0;
      *out_dist_sum = sse << 4;
      return;
    }
  
    if (!skip_dc) {
  #if CONFIG_VP9_HIGHBITDEPTH
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bsize],
                                   dc_quant >> (xd->bd - 5), &rate, &dist);
  #else
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bsize],
                                   dc_quant >> 3, &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
    }
  
    if (!skip_dc) {
      *out_rate_sum = rate >> 1;
      *out_dist_sum = dist << 3;
    } else {
      *out_rate_sum = 0;
      *out_dist_sum = (sse - var) << 4;
    }
  
  #if CONFIG_VP9_HIGHBITDEPTH
    vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bsize],
                                 ac_quant >> (xd->bd - 5), &rate, &dist);
  #else
    vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bsize], ac_quant >> 3,
                                 &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
  
    *out_rate_sum += rate;
    *out_dist_sum += dist << 4;
  }
  
  static void block_yrd(VP9_COMP *cpi, MACROBLOCK *x, RD_COST *this_rdc,
                        int *skippable, int64_t *sse, BLOCK_SIZE bsize,
                        TX_SIZE tx_size, int rd_computed) {
    MACROBLOCKD *xd = &x->e_mbd;
    const struct macroblockd_plane *pd = &xd->plane[0];
    struct macroblock_plane *const p = &x->plane[0];
    const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];
    const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];
    const int step = 1 << (tx_size << 1);
    const int block_step = (1 << tx_size);
    int block = 0, r, c;
    const int max_blocks_wide =
        num_4x4_w + (xd->mb_to_right_edge >= 0 ? 0 : xd->mb_to_right_edge >> 5);
    const int max_blocks_high =
        num_4x4_h + (xd->mb_to_bottom_edge >= 0 ? 0 : xd->mb_to_bottom_edge >> 5);
    int eob_cost = 0;
    const int bw = 4 * num_4x4_w;
    const int bh = 4 * num_4x4_h;
  
  #if CONFIG_VP9_HIGHBITDEPTH
    // TODO(jingning): Implement the high bit-depth Hadamard transforms and
    // remove this check condition.
    // TODO(marpan): Use this path (model_rd) for 8bit under certain conditions
    // for now, as the vp9_quantize_fp below for highbitdepth build is slow.
    if (xd->bd != 8 ||
        (cpi->oxcf.speed > 5 && cpi->common.frame_type != KEY_FRAME &&
         bsize < BLOCK_32X32)) {
      unsigned int var_y, sse_y;
      (void)tx_size;
      if (!rd_computed)
        model_rd_for_sb_y(cpi, bsize, x, xd, &this_rdc->rate, &this_rdc->dist,
                          &var_y, &sse_y);
      *sse = INT_MAX;
      *skippable = 0;
      return;
    }
  #endif
  
    if (cpi->sf.use_simple_block_yrd && cpi->common.frame_type != KEY_FRAME &&
        (bsize < BLOCK_32X32 ||
         (cpi->use_svc &&
          (bsize < BLOCK_32X32 || cpi->svc.temporal_layer_id > 0)))) {
      unsigned int var_y, sse_y;
      (void)tx_size;
      if (!rd_computed)
        model_rd_for_sb_y(cpi, bsize, x, xd, &this_rdc->rate, &this_rdc->dist,
                          &var_y, &sse_y);
      *sse = INT_MAX;
      *skippable = 0;
      return;
    }
  
    (void)cpi;
  
    // The max tx_size passed in is TX_16X16.
    assert(tx_size != TX_32X32);
  
    vpx_subtract_block(bh, bw, p->src_diff, bw, p->src.buf, p->src.stride,
                       pd->dst.buf, pd->dst.stride);
    *skippable = 1;
    // Keep track of the row and column of the blocks we use so that we know
    // if we are in the unrestricted motion border.
    for (r = 0; r < max_blocks_high; r += block_step) {
      for (c = 0; c < num_4x4_w; c += block_step) {
        if (c < max_blocks_wide) {
          const scan_order *const scan_order = &vp9_default_scan_orders[tx_size];
          tran_low_t *const coeff = BLOCK_OFFSET(p->coeff, block);
          tran_low_t *const qcoeff = BLOCK_OFFSET(p->qcoeff, block);
          tran_low_t *const dqcoeff = BLOCK_OFFSET(pd->dqcoeff, block);
          uint16_t *const eob = &p->eobs[block];
          const int diff_stride = bw;
          const int16_t *src_diff;
          src_diff = &p->src_diff[(r * diff_stride + c) << 2];
  
          switch (tx_size) {
            case TX_16X16:
              vpx_hadamard_16x16(src_diff, diff_stride, coeff);
              vp9_quantize_fp(coeff, 256, x->skip_block, p->round_fp, p->quant_fp,
                              qcoeff, dqcoeff, pd->dequant, eob, scan_order->scan,
                              scan_order->iscan);
              break;
            case TX_8X8:
              vpx_hadamard_8x8(src_diff, diff_stride, coeff);
              vp9_quantize_fp(coeff, 64, x->skip_block, p->round_fp, p->quant_fp,
                              qcoeff, dqcoeff, pd->dequant, eob, scan_order->scan,
                              scan_order->iscan);
              break;
            default:
              assert(tx_size == TX_4X4);
              x->fwd_txfm4x4(src_diff, coeff, diff_stride);
              vp9_quantize_fp(coeff, 16, x->skip_block, p->round_fp, p->quant_fp,
                              qcoeff, dqcoeff, pd->dequant, eob, scan_order->scan,
                              scan_order->iscan);
              break;
          }
          *skippable &= (*eob == 0);
          eob_cost += 1;
        }
        block += step;
      }
    }
  
    this_rdc->rate = 0;
    if (*sse < INT64_MAX) {
      *sse = (*sse << 6) >> 2;
      if (*skippable) {
        this_rdc->dist = *sse;
        return;
      }
    }
  
    block = 0;
    this_rdc->dist = 0;
    for (r = 0; r < max_blocks_high; r += block_step) {
      for (c = 0; c < num_4x4_w; c += block_step) {
        if (c < max_blocks_wide) {
          tran_low_t *const coeff = BLOCK_OFFSET(p->coeff, block);
          tran_low_t *const qcoeff = BLOCK_OFFSET(p->qcoeff, block);
          tran_low_t *const dqcoeff = BLOCK_OFFSET(pd->dqcoeff, block);
          uint16_t *const eob = &p->eobs[block];
  
          if (*eob == 1)
            this_rdc->rate += (int)abs(qcoeff[0]);
          else if (*eob > 1)
            this_rdc->rate += vpx_satd(qcoeff, step << 4);
  
          this_rdc->dist += vp9_block_error_fp(coeff, dqcoeff, step << 4) >> 2;
        }
        block += step;
      }
    }
  
    // If skippable is set, rate gets clobbered later.
    this_rdc->rate <<= (2 + VP9_PROB_COST_SHIFT);
    this_rdc->rate += (eob_cost << VP9_PROB_COST_SHIFT);
  }
  
  static void model_rd_for_sb_uv(VP9_COMP *cpi, BLOCK_SIZE plane_bsize,
                                 MACROBLOCK *x, MACROBLOCKD *xd,
                                 RD_COST *this_rdc, unsigned int *var_y,
                                 unsigned int *sse_y, int start_plane,
                                 int stop_plane) {
    // Note our transform coeffs are 8 times an orthogonal transform.
    // Hence quantizer step is also 8 times. To get effective quantizer
    // we need to divide by 8 before sending to modeling function.
    unsigned int sse;
    int rate;
    int64_t dist;
    int i;
  #if CONFIG_VP9_HIGHBITDEPTH
    uint64_t tot_var = *var_y;
    uint64_t tot_sse = *sse_y;
  #else
    uint32_t tot_var = *var_y;
    uint32_t tot_sse = *sse_y;
  #endif
  
    this_rdc->rate = 0;
    this_rdc->dist = 0;
  
    for (i = start_plane; i <= stop_plane; ++i) {
      struct macroblock_plane *const p = &x->plane[i];
      struct macroblockd_plane *const pd = &xd->plane[i];
      const uint32_t dc_quant = pd->dequant[0];
      const uint32_t ac_quant = pd->dequant[1];
      const BLOCK_SIZE bs = plane_bsize;
      unsigned int var;
      if (!x->color_sensitivity[i - 1]) continue;
  
      var = cpi->fn_ptr[bs].vf(p->src.buf, p->src.stride, pd->dst.buf,
                               pd->dst.stride, &sse);
      assert(sse >= var);
      tot_var += var;
      tot_sse += sse;
  
  #if CONFIG_VP9_HIGHBITDEPTH
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bs],
                                   dc_quant >> (xd->bd - 5), &rate, &dist);
  #else
      vp9_model_rd_from_var_lapndz(sse - var, num_pels_log2_lookup[bs],
                                   dc_quant >> 3, &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
  
      this_rdc->rate += rate >> 1;
      this_rdc->dist += dist << 3;
  
  #if CONFIG_VP9_HIGHBITDEPTH
      vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bs],
                                   ac_quant >> (xd->bd - 5), &rate, &dist);
  #else
      vp9_model_rd_from_var_lapndz(var, num_pels_log2_lookup[bs], ac_quant >> 3,
                                   &rate, &dist);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
  
      this_rdc->rate += rate;
      this_rdc->dist += dist << 4;
    }
  
  #if CONFIG_VP9_HIGHBITDEPTH
    *var_y = tot_var > UINT32_MAX ? UINT32_MAX : (uint32_t)tot_var;
    *sse_y = tot_sse > UINT32_MAX ? UINT32_MAX : (uint32_t)tot_sse;
  #else
    *var_y = tot_var;
    *sse_y = tot_sse;
  #endif
  }
  
  static int get_pred_buffer(PRED_BUFFER *p, int len) {
    int i;
  
    for (i = 0; i < len; i++) {
      if (!p[i].in_use) {
        p[i].in_use = 1;
        return i;
      }
    }
    return -1;
  }
  
  static void free_pred_buffer(PRED_BUFFER *p) {
    if (p != NULL) p->in_use = 0;
  }
  
  static void encode_breakout_test(
      VP9_COMP *cpi, MACROBLOCK *x, BLOCK_SIZE bsize, int mi_row, int mi_col,
      MV_REFERENCE_FRAME ref_frame, PREDICTION_MODE this_mode, unsigned int var_y,
      unsigned int sse_y, struct buf_2d yv12_mb[][MAX_MB_PLANE], int *rate,
      int64_t *dist, int *flag_preduv_computed) {
    MACROBLOCKD *xd = &x->e_mbd;
    MODE_INFO *const mi = xd->mi[0];
    const BLOCK_SIZE uv_size = get_plane_block_size(bsize, &xd->plane[1]);
    unsigned int var = var_y, sse = sse_y;
    // Skipping threshold for ac.
    unsigned int thresh_ac;
    // Skipping threshold for dc.
    unsigned int thresh_dc;
    int motion_low = 1;
    if (cpi->use_svc && ref_frame == GOLDEN_FRAME) return;
    if (mi->mv[0].as_mv.row > 64 || mi->mv[0].as_mv.row < -64 ||
        mi->mv[0].as_mv.col > 64 || mi->mv[0].as_mv.col < -64)
      motion_low = 0;
    if (x->encode_breakout > 0 && motion_low == 1) {
      // Set a maximum for threshold to avoid big PSNR loss in low bit rate
      // case. Use extreme low threshold for static frames to limit
      // skipping.
      const unsigned int max_thresh = 36000;
      // The encode_breakout input
      const unsigned int min_thresh =
          VPXMIN(((unsigned int)x->encode_breakout << 4), max_thresh);
  #if CONFIG_VP9_HIGHBITDEPTH
      const int shift = (xd->bd << 1) - 16;
  #endif
  
      // Calculate threshold according to dequant value.
      thresh_ac = (xd->plane[0].dequant[1] * xd->plane[0].dequant[1]) >> 3;
  #if CONFIG_VP9_HIGHBITDEPTH
      if ((xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) && shift > 0) {
        thresh_ac = ROUND_POWER_OF_TWO(thresh_ac, shift);
      }
  #endif  // CONFIG_VP9_HIGHBITDEPTH
      thresh_ac = clamp(thresh_ac, min_thresh, max_thresh);
  
      // Adjust ac threshold according to partition size.
      thresh_ac >>=
          8 - (b_width_log2_lookup[bsize] + b_height_log2_lookup[bsize]);
  
      thresh_dc = (xd->plane[0].dequant[0] * xd->plane[0].dequant[0] >> 6);
  #if CONFIG_VP9_HIGHBITDEPTH
      if ((xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) && shift > 0) {
        thresh_dc = ROUND_POWER_OF_TWO(thresh_dc, shift);
      }
  #endif  // CONFIG_VP9_HIGHBITDEPTH
    } else {
      thresh_ac = 0;
      thresh_dc = 0;
    }
  
    // Y skipping condition checking for ac and dc.
    if (var <= thresh_ac && (sse - var) <= thresh_dc) {
      unsigned int sse_u, sse_v;
      unsigned int var_u, var_v;
      unsigned int thresh_ac_uv = thresh_ac;
      unsigned int thresh_dc_uv = thresh_dc;
      if (x->sb_is_skin) {
        thresh_ac_uv = 0;
        thresh_dc_uv = 0;
      }
  
      if (!flag_preduv_computed[0] || !flag_preduv_computed[1]) {
        xd->plane[1].pre[0] = yv12_mb[ref_frame][1];
        xd->plane[2].pre[0] = yv12_mb[ref_frame][2];
        vp9_build_inter_predictors_sbuv(xd, mi_row, mi_col, bsize);
      }
  
      var_u = cpi->fn_ptr[uv_size].vf(x->plane[1].src.buf, x->plane[1].src.stride,
                                      xd->plane[1].dst.buf,
                                      xd->plane[1].dst.stride, &sse_u);
  
      // U skipping condition checking
      if (((var_u << 2) <= thresh_ac_uv) && (sse_u - var_u <= thresh_dc_uv)) {
        var_v = cpi->fn_ptr[uv_size].vf(
            x->plane[2].src.buf, x->plane[2].src.stride, xd->plane[2].dst.buf,
            xd->plane[2].dst.stride, &sse_v);
  
        // V skipping condition checking
        if (((var_v << 2) <= thresh_ac_uv) && (sse_v - var_v <= thresh_dc_uv)) {
          x->skip = 1;
  
          // The cost of skip bit needs to be added.
          *rate = cpi->inter_mode_cost[x->mbmi_ext->mode_context[ref_frame]]
                                      [INTER_OFFSET(this_mode)];
  
          // More on this part of rate
          // rate += vp9_cost_bit(vp9_get_skip_prob(cm, xd), 1);
  
          // Scaling factor for SSE from spatial domain to frequency
          // domain is 16. Adjust distortion accordingly.
          // TODO(yunqingwang): In this function, only y-plane dist is
          // calculated.
          *dist = (sse << 4);  // + ((sse_u + sse_v) << 4);
  
          // *disable_skip = 1;
        }
      }
    }
  }
  
  struct estimate_block_intra_args {
    VP9_COMP *cpi;
    MACROBLOCK *x;
    PREDICTION_MODE mode;
    int skippable;
    RD_COST *rdc;
  };
  
  static void estimate_block_intra(int plane, int block, int row, int col,
                                   BLOCK_SIZE plane_bsize, TX_SIZE tx_size,
                                   void *arg) {
    struct estimate_block_intra_args *const args = arg;
    VP9_COMP *const cpi = args->cpi;
    MACROBLOCK *const x = args->x;
    MACROBLOCKD *const xd = &x->e_mbd;
    struct macroblock_plane *const p = &x->plane[0];
    struct macroblockd_plane *const pd = &xd->plane[0];
    const BLOCK_SIZE bsize_tx = txsize_to_bsize[tx_size];
    uint8_t *const src_buf_base = p->src.buf;
    uint8_t *const dst_buf_base = pd->dst.buf;
    const int src_stride = p->src.stride;
    const int dst_stride = pd->dst.stride;
    RD_COST this_rdc;
  
    (void)block;
  
    p->src.buf = &src_buf_base[4 * (row * src_stride + col)];
    pd->dst.buf = &dst_buf_base[4 * (row * dst_stride + col)];
    // Use source buffer as an approximation for the fully reconstructed buffer.
    vp9_predict_intra_block(xd, b_width_log2_lookup[plane_bsize], tx_size,
                            args->mode, x->skip_encode ? p->src.buf : pd->dst.buf,
                            x->skip_encode ? src_stride : dst_stride, pd->dst.buf,
                            dst_stride, col, row, plane);
  
    if (plane == 0) {
      int64_t this_sse = INT64_MAX;
      // TODO(jingning): This needs further refactoring.
      block_yrd(cpi, x, &this_rdc, &args->skippable, &this_sse, bsize_tx,
                VPXMIN(tx_size, TX_16X16), 0);
    } else {
      unsigned int var = 0;
      unsigned int sse = 0;
      model_rd_for_sb_uv(cpi, plane_bsize, x, xd, &this_rdc, &var, &sse, plane,
                         plane);
    }
  
    p->src.buf = src_buf_base;
    pd->dst.buf = dst_buf_base;
    args->rdc->rate += this_rdc.rate;
    args->rdc->dist += this_rdc.dist;
  }
  
  static const THR_MODES mode_idx[MAX_REF_FRAMES][4] = {
    { THR_DC, THR_V_PRED, THR_H_PRED, THR_TM },
    { THR_NEARESTMV, THR_NEARMV, THR_ZEROMV, THR_NEWMV },
    { THR_NEARESTG, THR_NEARG, THR_ZEROG, THR_NEWG },
    { THR_NEARESTA, THR_NEARA, THR_ZEROA, THR_NEWA },
  };
  
  static const PREDICTION_MODE intra_mode_list[] = { DC_PRED, V_PRED, H_PRED,
                                                     TM_PRED };
  
  static int mode_offset(const PREDICTION_MODE mode) {
    if (mode >= NEARESTMV) {
      return INTER_OFFSET(mode);
    } else {
      switch (mode) {
        case DC_PRED: return 0;
        case V_PRED: return 1;
        case H_PRED: return 2;
        case TM_PRED: return 3;
        default: return -1;
      }
    }
  }
  
  static INLINE int rd_less_than_thresh_row_mt(int64_t best_rd, int thresh,
                                               const int *const thresh_fact) {
    int is_rd_less_than_thresh;
    is_rd_less_than_thresh =
        best_rd < ((int64_t)thresh * (*thresh_fact) >> 5) || thresh == INT_MAX;
    return is_rd_less_than_thresh;
  }
  
  static INLINE void update_thresh_freq_fact_row_mt(
      VP9_COMP *cpi, TileDataEnc *tile_data, int source_variance,
      int thresh_freq_fact_idx, MV_REFERENCE_FRAME ref_frame,
      THR_MODES best_mode_idx, PREDICTION_MODE mode) {
    THR_MODES thr_mode_idx = mode_idx[ref_frame][mode_offset(mode)];
    int freq_fact_idx = thresh_freq_fact_idx + thr_mode_idx;
    int *freq_fact = &tile_data->row_base_thresh_freq_fact[freq_fact_idx];
    if (thr_mode_idx == best_mode_idx)
      *freq_fact -= (*freq_fact >> 4);
    else if (cpi->sf.limit_newmv_early_exit && mode == NEWMV &&
             ref_frame == LAST_FRAME && source_variance < 5) {
      *freq_fact = VPXMIN(*freq_fact + RD_THRESH_INC, 32);
    } else {
      *freq_fact = VPXMIN(*freq_fact + RD_THRESH_INC,
                          cpi->sf.adaptive_rd_thresh * RD_THRESH_MAX_FACT);
    }
  }
  
  static INLINE void update_thresh_freq_fact(
      VP9_COMP *cpi, TileDataEnc *tile_data, int source_variance,
      BLOCK_SIZE bsize, MV_REFERENCE_FRAME ref_frame, THR_MODES best_mode_idx,
      PREDICTION_MODE mode) {
    THR_MODES thr_mode_idx = mode_idx[ref_frame][mode_offset(mode)];
    int *freq_fact = &tile_data->thresh_freq_fact[bsize][thr_mode_idx];
    if (thr_mode_idx == best_mode_idx)
      *freq_fact -= (*freq_fact >> 4);
    else if (cpi->sf.limit_newmv_early_exit && mode == NEWMV &&
             ref_frame == LAST_FRAME && source_variance < 5) {
      *freq_fact = VPXMIN(*freq_fact + RD_THRESH_INC, 32);
    } else {
      *freq_fact = VPXMIN(*freq_fact + RD_THRESH_INC,
                          cpi->sf.adaptive_rd_thresh * RD_THRESH_MAX_FACT);
    }
  }
  
  void vp9_pick_intra_mode(VP9_COMP *cpi, MACROBLOCK *x, RD_COST *rd_cost,
                           BLOCK_SIZE bsize, PICK_MODE_CONTEXT *ctx) {
    MACROBLOCKD *const xd = &x->e_mbd;
    MODE_INFO *const mi = xd->mi[0];
    RD_COST this_rdc, best_rdc;
    PREDICTION_MODE this_mode;
    struct estimate_block_intra_args args = { cpi, x, DC_PRED, 1, 0 };
    const TX_SIZE intra_tx_size =
        VPXMIN(max_txsize_lookup[bsize],
               tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
    MODE_INFO *const mic = xd->mi[0];
    int *bmode_costs;
    const MODE_INFO *above_mi = xd->above_mi;
    const MODE_INFO *left_mi = xd->left_mi;
    const PREDICTION_MODE A = vp9_above_block_mode(mic, above_mi, 0);
    const PREDICTION_MODE L = vp9_left_block_mode(mic, left_mi, 0);
    bmode_costs = cpi->y_mode_costs[A][L];
  
    (void)ctx;
    vp9_rd_cost_reset(&best_rdc);
    vp9_rd_cost_reset(&this_rdc);
  
    mi->ref_frame[0] = INTRA_FRAME;
    // Initialize interp_filter here so we do not have to check for inter block
    // modes in get_pred_context_switchable_interp()
    mi->interp_filter = SWITCHABLE_FILTERS;
  
    mi->mv[0].as_int = INVALID_MV;
    mi->uv_mode = DC_PRED;
    memset(x->skip_txfm, 0, sizeof(x->skip_txfm));
  
    // Change the limit of this loop to add other intra prediction
    // mode tests.
    for (this_mode = DC_PRED; this_mode <= H_PRED; ++this_mode) {
      this_rdc.dist = this_rdc.rate = 0;
      args.mode = this_mode;
      args.skippable = 1;
      args.rdc = &this_rdc;
      mi->tx_size = intra_tx_size;
      vp9_foreach_transformed_block_in_plane(xd, bsize, 0, estimate_block_intra,
                                             &args);
      if (args.skippable) {
        x->skip_txfm[0] = SKIP_TXFM_AC_DC;
        this_rdc.rate = vp9_cost_bit(vp9_get_skip_prob(&cpi->common, xd), 1);
      } else {
        x->skip_txfm[0] = SKIP_TXFM_NONE;
        this_rdc.rate += vp9_cost_bit(vp9_get_skip_prob(&cpi->common, xd), 0);
      }
      this_rdc.rate += bmode_costs[this_mode];
      this_rdc.rdcost = RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist);
  
      if (this_rdc.rdcost < best_rdc.rdcost) {
        best_rdc = this_rdc;
        mi->mode = this_mode;
      }
    }
  
    *rd_cost = best_rdc;
  }
  
  static void init_ref_frame_cost(VP9_COMMON *const cm, MACROBLOCKD *const xd,
                                  int ref_frame_cost[MAX_REF_FRAMES]) {
    vpx_prob intra_inter_p = vp9_get_intra_inter_prob(cm, xd);
    vpx_prob ref_single_p1 = vp9_get_pred_prob_single_ref_p1(cm, xd);
    vpx_prob ref_single_p2 = vp9_get_pred_prob_single_ref_p2(cm, xd);
  
    ref_frame_cost[INTRA_FRAME] = vp9_cost_bit(intra_inter_p, 0);
    ref_frame_cost[LAST_FRAME] = ref_frame_cost[GOLDEN_FRAME] =
        ref_frame_cost[ALTREF_FRAME] = vp9_cost_bit(intra_inter_p, 1);
  
    ref_frame_cost[LAST_FRAME] += vp9_cost_bit(ref_single_p1, 0);
    ref_frame_cost[GOLDEN_FRAME] += vp9_cost_bit(ref_single_p1, 1);
    ref_frame_cost[ALTREF_FRAME] += vp9_cost_bit(ref_single_p1, 1);
    ref_frame_cost[GOLDEN_FRAME] += vp9_cost_bit(ref_single_p2, 0);
    ref_frame_cost[ALTREF_FRAME] += vp9_cost_bit(ref_single_p2, 1);
  }
  
  typedef struct {
    MV_REFERENCE_FRAME ref_frame;
    PREDICTION_MODE pred_mode;
  } REF_MODE;
  
  #define RT_INTER_MODES 12
  static const REF_MODE ref_mode_set[RT_INTER_MODES] = {
    { LAST_FRAME, ZEROMV },   { LAST_FRAME, NEARESTMV },
    { GOLDEN_FRAME, ZEROMV }, { LAST_FRAME, NEARMV },
    { LAST_FRAME, NEWMV },    { GOLDEN_FRAME, NEARESTMV },
    { GOLDEN_FRAME, NEARMV }, { GOLDEN_FRAME, NEWMV },
    { ALTREF_FRAME, ZEROMV }, { ALTREF_FRAME, NEARESTMV },
    { ALTREF_FRAME, NEARMV }, { ALTREF_FRAME, NEWMV }
  };
  
  #define RT_INTER_MODES_SVC 8
  static const REF_MODE ref_mode_set_svc[RT_INTER_MODES_SVC] = {
    { LAST_FRAME, ZEROMV },      { LAST_FRAME, NEARESTMV },
    { LAST_FRAME, NEARMV },      { GOLDEN_FRAME, ZEROMV },
    { GOLDEN_FRAME, NEARESTMV }, { GOLDEN_FRAME, NEARMV },
    { LAST_FRAME, NEWMV },       { GOLDEN_FRAME, NEWMV }
  };
  
  static INLINE void find_predictors(
      VP9_COMP *cpi, MACROBLOCK *x, MV_REFERENCE_FRAME ref_frame,
      int_mv frame_mv[MB_MODE_COUNT][MAX_REF_FRAMES],
      int const_motion[MAX_REF_FRAMES], int *ref_frame_skip_mask,
      const int flag_list[4], TileDataEnc *tile_data, int mi_row, int mi_col,
      struct buf_2d yv12_mb[4][MAX_MB_PLANE], BLOCK_SIZE bsize,
      int force_skip_low_temp_var, int comp_pred_allowed) {
    VP9_COMMON *const cm = &cpi->common;
    MACROBLOCKD *const xd = &x->e_mbd;
    const YV12_BUFFER_CONFIG *yv12 = get_ref_frame_buffer(cpi, ref_frame);
    TileInfo *const tile_info = &tile_data->tile_info;
    // TODO(jingning) placeholder for inter-frame non-RD mode decision.
    x->pred_mv_sad[ref_frame] = INT_MAX;
    frame_mv[NEWMV][ref_frame].as_int = INVALID_MV;
    frame_mv[ZEROMV][ref_frame].as_int = 0;
    // this needs various further optimizations. to be continued..
    if ((cpi->ref_frame_flags & flag_list[ref_frame]) && (yv12 != NULL)) {
      int_mv *const candidates = x->mbmi_ext->ref_mvs[ref_frame];
      const struct scale_factors *const sf = &cm->frame_refs[ref_frame - 1].sf;
      vp9_setup_pred_block(xd, yv12_mb[ref_frame], yv12, mi_row, mi_col, sf, sf);
      if (cm->use_prev_frame_mvs || comp_pred_allowed) {
        vp9_find_mv_refs(cm, xd, xd->mi[0], ref_frame, candidates, mi_row, mi_col,
                         x->mbmi_ext->mode_context);
      } else {
        const_motion[ref_frame] =
            mv_refs_rt(cpi, cm, x, xd, tile_info, xd->mi[0], ref_frame,
                       candidates, &frame_mv[NEWMV][ref_frame], mi_row, mi_col,
                       (int)(cpi->svc.use_base_mv && cpi->svc.spatial_layer_id));
      }
      vp9_find_best_ref_mvs(xd, cm->allow_high_precision_mv, candidates,
                            &frame_mv[NEARESTMV][ref_frame],
                            &frame_mv[NEARMV][ref_frame]);
      // Early exit for golden frame if force_skip_low_temp_var is set.
      if (!vp9_is_scaled(sf) && bsize >= BLOCK_8X8 &&
          !(force_skip_low_temp_var && ref_frame == GOLDEN_FRAME)) {
        vp9_mv_pred(cpi, x, yv12_mb[ref_frame][0].buf, yv12->y_stride, ref_frame,
                    bsize);
      }
    } else {
      *ref_frame_skip_mask |= (1 << ref_frame);
    }
  }
  
  static void vp9_NEWMV_diff_bias(const NOISE_ESTIMATE *ne, MACROBLOCKD *xd,
                                  PREDICTION_MODE this_mode, RD_COST *this_rdc,
                                  BLOCK_SIZE bsize, int mv_row, int mv_col,
                                  int is_last_frame, int lowvar_highsumdiff,
                                  int is_skin) {
    // Bias against MVs associated with NEWMV mode that are very different from
    // top/left neighbors.
    if (this_mode == NEWMV) {
      int al_mv_average_row;
      int al_mv_average_col;
      int left_row, left_col;
      int row_diff, col_diff;
      int above_mv_valid = 0;
      int left_mv_valid = 0;
      int above_row = 0;
      int above_col = 0;
  
      if (xd->above_mi) {
        above_mv_valid = xd->above_mi->mv[0].as_int != INVALID_MV;
        above_row = xd->above_mi->mv[0].as_mv.row;
        above_col = xd->above_mi->mv[0].as_mv.col;
      }
      if (xd->left_mi) {
        left_mv_valid = xd->left_mi->mv[0].as_int != INVALID_MV;
        left_row = xd->left_mi->mv[0].as_mv.row;
        left_col = xd->left_mi->mv[0].as_mv.col;
      }
      if (above_mv_valid && left_mv_valid) {
        al_mv_average_row = (above_row + left_row + 1) >> 1;
        al_mv_average_col = (above_col + left_col + 1) >> 1;
      } else if (above_mv_valid) {
        al_mv_average_row = above_row;
        al_mv_average_col = above_col;
      } else if (left_mv_valid) {
        al_mv_average_row = left_row;
        al_mv_average_col = left_col;
      } else {
        al_mv_average_row = al_mv_average_col = 0;
      }
      row_diff = (al_mv_average_row - mv_row);
      col_diff = (al_mv_average_col - mv_col);
      if (row_diff > 48 || row_diff < -48 || col_diff > 48 || col_diff < -48) {
        if (bsize > BLOCK_32X32)
          this_rdc->rdcost = this_rdc->rdcost << 1;
        else
          this_rdc->rdcost = 3 * this_rdc->rdcost >> 1;
      }
    }
    // If noise estimation is enabled, and estimated level is above threshold,
    // add a bias to LAST reference with small motion, for large blocks.
    if (ne->enabled && ne->level >= kMedium && bsize >= BLOCK_32X32 &&
        is_last_frame && mv_row < 8 && mv_row > -8 && mv_col < 8 && mv_col > -8)
      this_rdc->rdcost = 7 * (this_rdc->rdcost >> 3);
    else if (lowvar_highsumdiff && !is_skin && bsize >= BLOCK_16X16 &&
             is_last_frame && mv_row < 16 && mv_row > -16 && mv_col < 16 &&
             mv_col > -16)
      this_rdc->rdcost = 7 * (this_rdc->rdcost >> 3);
  }
  
  #if CONFIG_VP9_TEMPORAL_DENOISING
  static void vp9_pickmode_ctx_den_update(
      VP9_PICKMODE_CTX_DEN *ctx_den, int64_t zero_last_cost_orig,
      int ref_frame_cost[MAX_REF_FRAMES],
      int_mv frame_mv[MB_MODE_COUNT][MAX_REF_FRAMES], int reuse_inter_pred,
      TX_SIZE best_tx_size, PREDICTION_MODE best_mode,
      MV_REFERENCE_FRAME best_ref_frame, INTERP_FILTER best_pred_filter,
      uint8_t best_mode_skip_txfm) {
    ctx_den->zero_last_cost_orig = zero_last_cost_orig;
    ctx_den->ref_frame_cost = ref_frame_cost;
    ctx_den->frame_mv = frame_mv;
    ctx_den->reuse_inter_pred = reuse_inter_pred;
    ctx_den->best_tx_size = best_tx_size;
    ctx_den->best_mode = best_mode;
    ctx_den->best_ref_frame = best_ref_frame;
    ctx_den->best_pred_filter = best_pred_filter;
    ctx_den->best_mode_skip_txfm = best_mode_skip_txfm;
  }
  
  static void recheck_zeromv_after_denoising(
      VP9_COMP *cpi, MODE_INFO *const mi, MACROBLOCK *x, MACROBLOCKD *const xd,
      VP9_DENOISER_DECISION decision, VP9_PICKMODE_CTX_DEN *ctx_den,
      struct buf_2d yv12_mb[4][MAX_MB_PLANE], RD_COST *best_rdc, BLOCK_SIZE bsize,
      int mi_row, int mi_col) {
    // If INTRA or GOLDEN reference was selected, re-evaluate ZEROMV on
    // denoised result. Only do this under noise conditions, and if rdcost of
    // ZEROMV onoriginal source is not significantly higher than rdcost of best
    // mode.
    if (cpi->noise_estimate.enabled && cpi->noise_estimate.level > kLow &&
        ctx_den->zero_last_cost_orig < (best_rdc->rdcost << 3) &&
        ((ctx_den->best_ref_frame == INTRA_FRAME && decision >= FILTER_BLOCK) ||
         (ctx_den->best_ref_frame == GOLDEN_FRAME &&
          cpi->svc.number_spatial_layers == 1 &&
          decision == FILTER_ZEROMV_BLOCK))) {
      // Check if we should pick ZEROMV on denoised signal.
      int rate = 0;
      int64_t dist = 0;
      uint32_t var_y = UINT_MAX;
      uint32_t sse_y = UINT_MAX;
      RD_COST this_rdc;
      mi->mode = ZEROMV;
      mi->ref_frame[0] = LAST_FRAME;
      mi->ref_frame[1] = NONE;
      mi->mv[0].as_int = 0;
      mi->interp_filter = EIGHTTAP;
      if (cpi->sf.default_interp_filter == BILINEAR) mi->interp_filter = BILINEAR;
      xd->plane[0].pre[0] = yv12_mb[LAST_FRAME][0];
      vp9_build_inter_predictors_sby(xd, mi_row, mi_col, bsize);
      model_rd_for_sb_y(cpi, bsize, x, xd, &rate, &dist, &var_y, &sse_y);
      this_rdc.rate = rate + ctx_den->ref_frame_cost[LAST_FRAME] +
                      cpi->inter_mode_cost[x->mbmi_ext->mode_context[LAST_FRAME]]
                                          [INTER_OFFSET(ZEROMV)];
      this_rdc.dist = dist;
      this_rdc.rdcost = RDCOST(x->rdmult, x->rddiv, rate, dist);
      // Don't switch to ZEROMV if the rdcost for ZEROMV on denoised source
      // is higher than best_ref mode (on original source).
      if (this_rdc.rdcost > best_rdc->rdcost) {
        this_rdc = *best_rdc;
        mi->mode = ctx_den->best_mode;
        mi->ref_frame[0] = ctx_den->best_ref_frame;
        mi->interp_filter = ctx_den->best_pred_filter;
        if (ctx_den->best_ref_frame == INTRA_FRAME) {
          mi->mv[0].as_int = INVALID_MV;
          mi->interp_filter = SWITCHABLE_FILTERS;
        } else if (ctx_den->best_ref_frame == GOLDEN_FRAME) {
          mi->mv[0].as_int =
              ctx_den->frame_mv[ctx_den->best_mode][ctx_den->best_ref_frame]
                  .as_int;
          if (ctx_den->reuse_inter_pred) {
            xd->plane[0].pre[0] = yv12_mb[GOLDEN_FRAME][0];
            vp9_build_inter_predictors_sby(xd, mi_row, mi_col, bsize);
          }
        }
        mi->tx_size = ctx_den->best_tx_size;
        x->skip_txfm[0] = ctx_den->best_mode_skip_txfm;
      } else {
        ctx_den->best_ref_frame = LAST_FRAME;
        *best_rdc = this_rdc;
      }
    }
  }
  #endif  // CONFIG_VP9_TEMPORAL_DENOISING
  
  static INLINE int get_force_skip_low_temp_var(uint8_t *variance_low, int mi_row,
                                                int mi_col, BLOCK_SIZE bsize) {
    const int i = (mi_row & 0x7) >> 1;
    const int j = (mi_col & 0x7) >> 1;
    int force_skip_low_temp_var = 0;
    // Set force_skip_low_temp_var based on the block size and block offset.
    if (bsize == BLOCK_64X64) {
      force_skip_low_temp_var = variance_low[0];
    } else if (bsize == BLOCK_64X32) {
      if (!(mi_col & 0x7) && !(mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[1];
      } else if (!(mi_col & 0x7) && (mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[2];
      }
    } else if (bsize == BLOCK_32X64) {
      if (!(mi_col & 0x7) && !(mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[3];
      } else if ((mi_col & 0x7) && !(mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[4];
      }
    } else if (bsize == BLOCK_32X32) {
      if (!(mi_col & 0x7) && !(mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[5];
      } else if ((mi_col & 0x7) && !(mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[6];
      } else if (!(mi_col & 0x7) && (mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[7];
      } else if ((mi_col & 0x7) && (mi_row & 0x7)) {
        force_skip_low_temp_var = variance_low[8];
      }
    } else if (bsize == BLOCK_16X16) {
      force_skip_low_temp_var = variance_low[pos_shift_16x16[i][j]];
    } else if (bsize == BLOCK_32X16) {
      // The col shift index for the second 16x16 block.
      const int j2 = ((mi_col + 2) & 0x7) >> 1;
      // Only if each 16x16 block inside has low temporal variance.
      force_skip_low_temp_var = variance_low[pos_shift_16x16[i][j]] &&
                                variance_low[pos_shift_16x16[i][j2]];
    } else if (bsize == BLOCK_16X32) {
      // The row shift index for the second 16x16 block.
      const int i2 = ((mi_row + 2) & 0x7) >> 1;
      force_skip_low_temp_var = variance_low[pos_shift_16x16[i][j]] &&
                                variance_low[pos_shift_16x16[i2][j]];
    }
    return force_skip_low_temp_var;
  }
  
  void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x, TileDataEnc *tile_data,
                           int mi_row, int mi_col, RD_COST *rd_cost,
                           BLOCK_SIZE bsize, PICK_MODE_CONTEXT *ctx) {
    VP9_COMMON *const cm = &cpi->common;
    SPEED_FEATURES *const sf = &cpi->sf;
    SVC *const svc = &cpi->svc;
    MACROBLOCKD *const xd = &x->e_mbd;
    MODE_INFO *const mi = xd->mi[0];
    struct macroblockd_plane *const pd = &xd->plane[0];
    PREDICTION_MODE best_mode = ZEROMV;
    MV_REFERENCE_FRAME ref_frame, best_ref_frame = LAST_FRAME;
    MV_REFERENCE_FRAME usable_ref_frame, second_ref_frame;
    TX_SIZE best_tx_size = TX_SIZES;
    INTERP_FILTER best_pred_filter = EIGHTTAP;
    int_mv frame_mv[MB_MODE_COUNT][MAX_REF_FRAMES];
    uint8_t mode_checked[MB_MODE_COUNT][MAX_REF_FRAMES];
    struct buf_2d yv12_mb[4][MAX_MB_PLANE];
    static const int flag_list[4] = { 0, VP9_LAST_FLAG, VP9_GOLD_FLAG,
                                      VP9_ALT_FLAG };
    RD_COST this_rdc, best_rdc;
    uint8_t skip_txfm = SKIP_TXFM_NONE, best_mode_skip_txfm = SKIP_TXFM_NONE;
    // var_y and sse_y are saved to be used in skipping checking
    unsigned int var_y = UINT_MAX;
    unsigned int sse_y = UINT_MAX;
    const int intra_cost_penalty =
        vp9_get_intra_cost_penalty(cpi, bsize, cm->base_qindex, cm->y_dc_delta_q);
    int64_t inter_mode_thresh =
        RDCOST(x->rdmult, x->rddiv, intra_cost_penalty, 0);
    const int *const rd_threshes = cpi->rd.threshes[mi->segment_id][bsize];
    const int sb_row = mi_row >> MI_BLOCK_SIZE_LOG2;
    int thresh_freq_fact_idx = (sb_row * BLOCK_SIZES + bsize) * MAX_MODES;
    const int *const rd_thresh_freq_fact =
        (cpi->sf.adaptive_rd_thresh_row_mt)
            ? &(tile_data->row_base_thresh_freq_fact[thresh_freq_fact_idx])
            : tile_data->thresh_freq_fact[bsize];
  
    INTERP_FILTER filter_ref;
    const int bsl = mi_width_log2_lookup[bsize];
    const int pred_filter_search =
        cm->interp_filter == SWITCHABLE
            ? (((mi_row + mi_col) >> bsl) +
               get_chessboard_index(cm->current_video_frame)) &
                  0x1
            : 0;
    int const_motion[MAX_REF_FRAMES] = { 0 };
    const int bh = num_4x4_blocks_high_lookup[bsize] << 2;
    const int bw = num_4x4_blocks_wide_lookup[bsize] << 2;
    // For speed 6, the result of interp filter is reused later in actual encoding
    // process.
    // tmp[3] points to dst buffer, and the other 3 point to allocated buffers.
    PRED_BUFFER tmp[4];
    DECLARE_ALIGNED(16, uint8_t, pred_buf[3 * 64 * 64]);
  #if CONFIG_VP9_HIGHBITDEPTH
    DECLARE_ALIGNED(16, uint16_t, pred_buf_16[3 * 64 * 64]);
  #endif
    struct buf_2d orig_dst = pd->dst;
    PRED_BUFFER *best_pred = NULL;
    PRED_BUFFER *this_mode_pred = NULL;
    const int pixels_in_block = bh * bw;
    int reuse_inter_pred = cpi->sf.reuse_inter_pred_sby && ctx->pred_pixel_ready;
    int ref_frame_skip_mask = 0;
    int idx;
    int best_pred_sad = INT_MAX;
    int best_early_term = 0;
    int ref_frame_cost[MAX_REF_FRAMES];
    int svc_force_zero_mode[3] = { 0 };
    int perform_intra_pred = 1;
    int use_golden_nonzeromv = 1;
    int force_skip_low_temp_var = 0;
    int skip_ref_find_pred[4] = { 0 };
    unsigned int sse_zeromv_normalized = UINT_MAX;
    unsigned int best_sse_sofar = UINT_MAX;
    int gf_is_longterm_ref = 0;
  #if CONFIG_VP9_TEMPORAL_DENOISING
    VP9_PICKMODE_CTX_DEN ctx_den;
    int64_t zero_last_cost_orig = INT64_MAX;
    int denoise_svc_pickmode = 1;
  #endif
    INTERP_FILTER filter_gf_svc = EIGHTTAP;
    MV_REFERENCE_FRAME best_second_ref_frame = NONE;
    MV_REFERENCE_FRAME inter_layer_ref = GOLDEN_FRAME;
    const struct segmentation *const seg = &cm->seg;
    int comp_modes = 0;
    int num_inter_modes = (cpi->use_svc) ? RT_INTER_MODES_SVC : RT_INTER_MODES;
    int flag_svc_subpel = 0;
    int svc_mv_col = 0;
    int svc_mv_row = 0;
    int no_scaling = 0;
    unsigned int thresh_svc_skip_golden = 500;
    if (cpi->sf.default_interp_filter == BILINEAR) {
      best_pred_filter = BILINEAR;
      filter_gf_svc = BILINEAR;
    }
    if (cpi->use_svc && svc->spatial_layer_id > 0) {
      int layer =
          LAYER_IDS_TO_IDX(svc->spatial_layer_id - 1, svc->temporal_layer_id,
                           svc->number_temporal_layers);
      LAYER_CONTEXT *const lc = &svc->layer_context[layer];
      if (lc->scaling_factor_num == lc->scaling_factor_den) no_scaling = 1;
    }
    if (svc->spatial_layer_id > 0 &&
        (svc->high_source_sad_superframe || no_scaling))
      thresh_svc_skip_golden = 0;
    // Lower the skip threshold if lower spatial layer is better quality relative
    // to current layer.
    else if (svc->spatial_layer_id > 0 && cm->base_qindex > 150 &&
             cm->base_qindex > svc->lower_layer_qindex + 15)
      thresh_svc_skip_golden = 100;
    // Increase skip threshold if lower spatial layer is lower quality relative
    // to current layer.
    else if (svc->spatial_layer_id > 0 && cm->base_qindex < 140 &&
             cm->base_qindex < svc->lower_layer_qindex - 20)
      thresh_svc_skip_golden = 1000;
  
    if (!cpi->use_svc ||
        (svc->use_longterm_ref_current_layer &&
         !svc->layer_context[svc->temporal_layer_id].is_key_frame))
      gf_is_longterm_ref = 1;
  
    init_ref_frame_cost(cm, xd, ref_frame_cost);
    memset(&mode_checked[0][0], 0, MB_MODE_COUNT * MAX_REF_FRAMES);
  
    if (reuse_inter_pred) {
      int i;
      for (i = 0; i < 3; i++) {
  #if CONFIG_VP9_HIGHBITDEPTH
        if (cm->use_highbitdepth)
          tmp[i].data = CONVERT_TO_BYTEPTR(&pred_buf_16[pixels_in_block * i]);
        else
          tmp[i].data = &pred_buf[pixels_in_block * i];
  #else
        tmp[i].data = &pred_buf[pixels_in_block * i];
  #endif  // CONFIG_VP9_HIGHBITDEPTH
        tmp[i].stride = bw;
        tmp[i].in_use = 0;
      }
      tmp[3].data = pd->dst.buf;
      tmp[3].stride = pd->dst.stride;
      tmp[3].in_use = 0;
    }
  
    x->skip_encode = cpi->sf.skip_encode_frame && x->q_index < QIDX_SKIP_THRESH;
    x->skip = 0;
  
    // Instead of using vp9_get_pred_context_switchable_interp(xd) to assign
    // filter_ref, we use a less strict condition on assigning filter_ref.
    // This is to reduce the probabily of entering the flow of not assigning
    // filter_ref and then skip filter search.
    filter_ref = cm->interp_filter;
    if (cpi->sf.default_interp_filter != BILINEAR) {
      if (xd->above_mi && is_inter_block(xd->above_mi))
        filter_ref = xd->above_mi->interp_filter;
      else if (xd->left_mi && is_inter_block(xd->left_mi))
        filter_ref = xd->left_mi->interp_filter;
    }
  
    // initialize mode decisions
    vp9_rd_cost_reset(&best_rdc);
    vp9_rd_cost_reset(rd_cost);
    mi->sb_type = bsize;
    mi->ref_frame[0] = NONE;
    mi->ref_frame[1] = NONE;
  
    mi->tx_size =
        VPXMIN(max_txsize_lookup[bsize], tx_mode_to_biggest_tx_size[cm->tx_mode]);
  
    if (sf->short_circuit_flat_blocks || sf->limit_newmv_early_exit) {
  #if CONFIG_VP9_HIGHBITDEPTH
      if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH)
        x->source_variance = vp9_high_get_sby_perpixel_variance(
            cpi, &x->plane[0].src, bsize, xd->bd);
      else
  #endif  // CONFIG_VP9_HIGHBITDEPTH
        x->source_variance =
            vp9_get_sby_perpixel_variance(cpi, &x->plane[0].src, bsize);
    }
  
  #if CONFIG_VP9_TEMPORAL_DENOISING
    if (cpi->oxcf.noise_sensitivity > 0) {
      if (cpi->use_svc) {
        int layer =
            LAYER_IDS_TO_IDX(svc->spatial_layer_id, svc->temporal_layer_id,
                             svc->number_temporal_layers);
        LAYER_CONTEXT *lc = &svc->layer_context[layer];
        denoise_svc_pickmode = denoise_svc(cpi) && !lc->is_key_frame;
      }
      if (cpi->denoiser.denoising_level > kDenLowLow && denoise_svc_pickmode)
        vp9_denoiser_reset_frame_stats(ctx);
    }
  #endif
  
    if (cpi->rc.frames_since_golden == 0 && gf_is_longterm_ref &&
        !cpi->rc.alt_ref_gf_group && !cpi->rc.last_frame_is_src_altref) {
      usable_ref_frame = LAST_FRAME;
    } else {
      usable_ref_frame = GOLDEN_FRAME;
    }
  
    if (cpi->oxcf.lag_in_frames > 0 && cpi->oxcf.rc_mode == VPX_VBR) {
      if (cpi->rc.alt_ref_gf_group || cpi->rc.is_src_frame_alt_ref)
        usable_ref_frame = ALTREF_FRAME;
  
      if (cpi->rc.is_src_frame_alt_ref) {
        skip_ref_find_pred[LAST_FRAME] = 1;
        skip_ref_find_pred[GOLDEN_FRAME] = 1;
      }
      if (!cm->show_frame) {
        if (cpi->rc.frames_since_key == 1) {
          usable_ref_frame = LAST_FRAME;
          skip_ref_find_pred[GOLDEN_FRAME] = 1;
          skip_ref_find_pred[ALTREF_FRAME] = 1;
        }
      }
    }
  
    // For svc mode, on spatial_layer_id > 0: if the reference has different scale
    // constrain the inter mode to only test zero motion.
    if (cpi->use_svc && svc->force_zero_mode_spatial_ref &&
        svc->spatial_layer_id > 0 && !gf_is_longterm_ref) {
      if (cpi->ref_frame_flags & flag_list[LAST_FRAME]) {
        struct scale_factors *const sf = &cm->frame_refs[LAST_FRAME - 1].sf;
        if (vp9_is_scaled(sf)) {
          svc_force_zero_mode[LAST_FRAME - 1] = 1;
          inter_layer_ref = LAST_FRAME;
        }
      }
      if (cpi->ref_frame_flags & flag_list[GOLDEN_FRAME]) {
        struct scale_factors *const sf = &cm->frame_refs[GOLDEN_FRAME - 1].sf;
        if (vp9_is_scaled(sf)) {
          svc_force_zero_mode[GOLDEN_FRAME - 1] = 1;
          inter_layer_ref = GOLDEN_FRAME;
        }
      }
    }
  
    if (cpi->sf.short_circuit_low_temp_var) {
      force_skip_low_temp_var =
          get_force_skip_low_temp_var(&x->variance_low[0], mi_row, mi_col, bsize);
      // If force_skip_low_temp_var is set, and for short circuit mode = 1 and 3,
      // skip golden reference.
      if ((cpi->sf.short_circuit_low_temp_var == 1 ||
           cpi->sf.short_circuit_low_temp_var == 3) &&
          force_skip_low_temp_var) {
        usable_ref_frame = LAST_FRAME;
      }
    }
  
    if (sf->disable_golden_ref && (x->content_state_sb != kVeryHighSad ||
                                   cpi->rc.avg_frame_low_motion < 60))
      usable_ref_frame = LAST_FRAME;
  
    if (!((cpi->ref_frame_flags & flag_list[GOLDEN_FRAME]) &&
          !svc_force_zero_mode[GOLDEN_FRAME - 1] && !force_skip_low_temp_var))
      use_golden_nonzeromv = 0;
  
    if (cpi->oxcf.speed >= 8 && !cpi->use_svc &&
        ((cpi->rc.frames_since_golden + 1) < x->last_sb_high_content ||
         x->last_sb_high_content > 40 || cpi->rc.frames_since_golden > 120))
      usable_ref_frame = LAST_FRAME;
  
    // Compound prediction modes: (0,0) on LAST/GOLDEN and ARF.
    if (cm->reference_mode == REFERENCE_MODE_SELECT &&
        cpi->sf.use_compound_nonrd_pickmode && usable_ref_frame == ALTREF_FRAME)
      comp_modes = 2;
  
    // If the segment reference frame feature is enabled and it's set to GOLDEN
    // reference, then make sure we don't skip checking GOLDEN, this is to
    // prevent possibility of not picking any mode.
    if (segfeature_active(seg, mi->segment_id, SEG_LVL_REF_FRAME) &&
        get_segdata(seg, mi->segment_id, SEG_LVL_REF_FRAME) == GOLDEN_FRAME) {
      usable_ref_frame = GOLDEN_FRAME;
      skip_ref_find_pred[GOLDEN_FRAME] = 0;
      thresh_svc_skip_golden = 0;
    }
  
    for (ref_frame = LAST_FRAME; ref_frame <= usable_ref_frame; ++ref_frame) {
      // Skip find_predictor if the reference frame is not in the
      // ref_frame_flags (i.e., not used as a reference for this frame).
      skip_ref_find_pred[ref_frame] =
          !(cpi->ref_frame_flags & flag_list[ref_frame]);
      if (!skip_ref_find_pred[ref_frame]) {
        find_predictors(cpi, x, ref_frame, frame_mv, const_motion,
                        &ref_frame_skip_mask, flag_list, tile_data, mi_row,
                        mi_col, yv12_mb, bsize, force_skip_low_temp_var,
                        comp_modes > 0);
      }
    }
  
    if (cpi->use_svc || cpi->oxcf.speed <= 7 || bsize < BLOCK_32X32)
      x->sb_use_mv_part = 0;
  
    // Set the flag_svc_subpel to 1 for SVC if the lower spatial layer used
    // an averaging filter for downsampling (phase = 8). If so, we will test
    // a nonzero motion mode on the spatial reference.
    // The nonzero motion is half pixel shifted to left and top (-4, -4).
    if (cpi->use_svc && svc->spatial_layer_id > 0 &&
        svc_force_zero_mode[inter_layer_ref - 1] &&
        svc->downsample_filter_phase[svc->spatial_layer_id - 1] == 8 &&
        !gf_is_longterm_ref) {
      svc_mv_col = -4;
      svc_mv_row = -4;
      flag_svc_subpel = 1;
    }
  
    for (idx = 0; idx < num_inter_modes + comp_modes; ++idx) {
      int rate_mv = 0;
      int mode_rd_thresh;
      int mode_index;
      int i;
      int64_t this_sse;
      int is_skippable;
      int this_early_term = 0;
      int rd_computed = 0;
      int flag_preduv_computed[2] = { 0 };
      int inter_mv_mode = 0;
      int skip_this_mv = 0;
      int comp_pred = 0;
      int force_mv_inter_layer = 0;
      PREDICTION_MODE this_mode;
      second_ref_frame = NONE;
  
      if (idx < num_inter_modes) {
        this_mode = ref_mode_set[idx].pred_mode;
        ref_frame = ref_mode_set[idx].ref_frame;
  
        if (cpi->use_svc) {
          this_mode = ref_mode_set_svc[idx].pred_mode;
          ref_frame = ref_mode_set_svc[idx].ref_frame;
        }
      } else {
        // Add (0,0) compound modes.
        this_mode = ZEROMV;
        ref_frame = LAST_FRAME;
        if (idx == num_inter_modes + comp_modes - 1) ref_frame = GOLDEN_FRAME;
        second_ref_frame = ALTREF_FRAME;
        comp_pred = 1;
      }
  
      if (ref_frame > usable_ref_frame) continue;
      if (skip_ref_find_pred[ref_frame]) continue;
  
      // If the segment reference frame feature is enabled then do nothing if the
      // current ref frame is not allowed.
      if (segfeature_active(seg, mi->segment_id, SEG_LVL_REF_FRAME) &&
          get_segdata(seg, mi->segment_id, SEG_LVL_REF_FRAME) != (int)ref_frame)
        continue;
  
      if (flag_svc_subpel && ref_frame == inter_layer_ref) {
        force_mv_inter_layer = 1;
        // Only test mode if NEARESTMV/NEARMV is (svc_mv_col, svc_mv_row),
        // otherwise set NEWMV to (svc_mv_col, svc_mv_row).
        if (this_mode == NEWMV) {
          frame_mv[this_mode][ref_frame].as_mv.col = svc_mv_col;
          frame_mv[this_mode][ref_frame].as_mv.row = svc_mv_row;
        } else if (frame_mv[this_mode][ref_frame].as_mv.col != svc_mv_col ||
                   frame_mv[this_mode][ref_frame].as_mv.row != svc_mv_row) {
          continue;
        }
      }
  
      if (comp_pred) {
        if (!cpi->allow_comp_inter_inter) continue;
        // Skip compound inter modes if ARF is not available.
        if (!(cpi->ref_frame_flags & flag_list[second_ref_frame])) continue;
        // Do not allow compound prediction if the segment level reference frame
        // feature is in use as in this case there can only be one reference.
        if (segfeature_active(seg, mi->segment_id, SEG_LVL_REF_FRAME)) continue;
      }
  
      // For SVC, skip the golden (spatial) reference search if sse of zeromv_last
      // is below threshold.
      if (cpi->use_svc && ref_frame == GOLDEN_FRAME && !gf_is_longterm_ref &&
          sse_zeromv_normalized < thresh_svc_skip_golden)
        continue;
  
      if (!(cpi->ref_frame_flags & flag_list[ref_frame])) continue;
  
      if (sf->short_circuit_flat_blocks && x->source_variance == 0 &&
          frame_mv[this_mode][ref_frame].as_int != 0) {
        continue;
      }
  
      if (!(cpi->sf.inter_mode_mask[bsize] & (1 << this_mode))) continue;
  
      if (cpi->oxcf.lag_in_frames > 0 && cpi->oxcf.rc_mode == VPX_VBR) {
        if (cpi->rc.is_src_frame_alt_ref &&
            (ref_frame != ALTREF_FRAME ||
             frame_mv[this_mode][ref_frame].as_int != 0))
          continue;
  
        if (!cm->show_frame && ref_frame == ALTREF_FRAME &&
            frame_mv[this_mode][ref_frame].as_int != 0)
          continue;
  
        if (cpi->rc.alt_ref_gf_group && cm->show_frame &&
            cpi->rc.frames_since_golden > (cpi->rc.baseline_gf_interval >> 1) &&
            ref_frame == GOLDEN_FRAME &&
            frame_mv[this_mode][ref_frame].as_int != 0)
          continue;
  
        if (cpi->rc.alt_ref_gf_group && cm->show_frame &&
            cpi->rc.frames_since_golden > 0 &&
            cpi->rc.frames_since_golden < (cpi->rc.baseline_gf_interval >> 1) &&
            ref_frame == ALTREF_FRAME &&
            frame_mv[this_mode][ref_frame].as_int != 0)
          continue;
      }
  
      if (const_motion[ref_frame] && this_mode == NEARMV) continue;
  
      // Skip non-zeromv mode search for golden frame if force_skip_low_temp_var
      // is set. If nearestmv for golden frame is 0, zeromv mode will be skipped
      // later.
      if (!force_mv_inter_layer && force_skip_low_temp_var &&
          ref_frame == GOLDEN_FRAME &&
          frame_mv[this_mode][ref_frame].as_int != 0) {
        continue;
      }
  
      if (x->content_state_sb != kVeryHighSad &&
          (cpi->sf.short_circuit_low_temp_var >= 2 ||
           (cpi->sf.short_circuit_low_temp_var == 1 && bsize == BLOCK_64X64)) &&
          force_skip_low_temp_var && ref_frame == LAST_FRAME &&
          this_mode == NEWMV) {
        continue;
      }
  
      if (cpi->use_svc) {
        if (!force_mv_inter_layer && svc_force_zero_mode[ref_frame - 1] &&
            frame_mv[this_mode][ref_frame].as_int != 0)
          continue;
      }
  
      // Disable this drop out case if the ref frame segment level feature is
      // enabled for this segment. This is to prevent the possibility that we end
      // up unable to pick any mode.
      if (!segfeature_active(seg, mi->segment_id, SEG_LVL_REF_FRAME)) {
        if (sf->reference_masking &&
            !(frame_mv[this_mode][ref_frame].as_int == 0 &&
              ref_frame == LAST_FRAME)) {
          if (usable_ref_frame < ALTREF_FRAME) {
            if (!force_skip_low_temp_var && usable_ref_frame > LAST_FRAME) {
              i = (ref_frame == LAST_FRAME) ? GOLDEN_FRAME : LAST_FRAME;
              if ((cpi->ref_frame_flags & flag_list[i]))
                if (x->pred_mv_sad[ref_frame] > (x->pred_mv_sad[i] << 1))
                  ref_frame_skip_mask |= (1 << ref_frame);
            }
          } else if (!cpi->rc.is_src_frame_alt_ref &&
                     !(frame_mv[this_mode][ref_frame].as_int == 0 &&
                       ref_frame == ALTREF_FRAME)) {
            int ref1 = (ref_frame == GOLDEN_FRAME) ? LAST_FRAME : GOLDEN_FRAME;
            int ref2 = (ref_frame == ALTREF_FRAME) ? LAST_FRAME : ALTREF_FRAME;
            if (((cpi->ref_frame_flags & flag_list[ref1]) &&
                 (x->pred_mv_sad[ref_frame] > (x->pred_mv_sad[ref1] << 1))) ||
                ((cpi->ref_frame_flags & flag_list[ref2]) &&
                 (x->pred_mv_sad[ref_frame] > (x->pred_mv_sad[ref2] << 1))))
              ref_frame_skip_mask |= (1 << ref_frame);
          }
        }
        if (ref_frame_skip_mask & (1 << ref_frame)) continue;
      }
  
      // Select prediction reference frames.
      for (i = 0; i < MAX_MB_PLANE; i++) {
        xd->plane[i].pre[0] = yv12_mb[ref_frame][i];
        if (comp_pred) xd->plane[i].pre[1] = yv12_mb[second_ref_frame][i];
      }
  
      mi->ref_frame[0] = ref_frame;
      mi->ref_frame[1] = second_ref_frame;
      set_ref_ptrs(cm, xd, ref_frame, second_ref_frame);
  
      mode_index = mode_idx[ref_frame][INTER_OFFSET(this_mode)];
      mode_rd_thresh = best_mode_skip_txfm ? rd_threshes[mode_index] << 1
                                           : rd_threshes[mode_index];
  
      // Increase mode_rd_thresh value for GOLDEN_FRAME for improved encoding
      // speed with little/no subjective quality loss.
      if (cpi->sf.bias_golden && ref_frame == GOLDEN_FRAME &&
          cpi->rc.frames_since_golden > 4)
        mode_rd_thresh = mode_rd_thresh << 3;
  
      if ((cpi->sf.adaptive_rd_thresh_row_mt &&
           rd_less_than_thresh_row_mt(best_rdc.rdcost, mode_rd_thresh,
                                      &rd_thresh_freq_fact[mode_index])) ||
          (!cpi->sf.adaptive_rd_thresh_row_mt &&
           rd_less_than_thresh(best_rdc.rdcost, mode_rd_thresh,
                               &rd_thresh_freq_fact[mode_index])))
        if (frame_mv[this_mode][ref_frame].as_int != 0) continue;
  
      if (this_mode == NEWMV && !force_mv_inter_layer) {
        if (ref_frame > LAST_FRAME && gf_is_longterm_ref &&
            cpi->oxcf.rc_mode == VPX_CBR) {
          int tmp_sad;
          uint32_t dis;
          int cost_list[5] = { INT_MAX, INT_MAX, INT_MAX, INT_MAX, INT_MAX };
  
          if (bsize < BLOCK_16X16) continue;
  
          tmp_sad = vp9_int_pro_motion_estimation(
              cpi, x, bsize, mi_row, mi_col,
              &x->mbmi_ext->ref_mvs[ref_frame][0].as_mv);
  
          if (tmp_sad > x->pred_mv_sad[LAST_FRAME]) continue;
          if (tmp_sad + (num_pels_log2_lookup[bsize] << 4) > best_pred_sad)
            continue;
  
          frame_mv[NEWMV][ref_frame].as_int = mi->mv[0].as_int;
          rate_mv = vp9_mv_bit_cost(&frame_mv[NEWMV][ref_frame].as_mv,
                                    &x->mbmi_ext->ref_mvs[ref_frame][0].as_mv,
                                    x->nmvjointcost, x->mvcost, MV_COST_WEIGHT);
          frame_mv[NEWMV][ref_frame].as_mv.row >>= 3;
          frame_mv[NEWMV][ref_frame].as_mv.col >>= 3;
  
          cpi->find_fractional_mv_step(
              x, &frame_mv[NEWMV][ref_frame].as_mv,
              &x->mbmi_ext->ref_mvs[ref_frame][0].as_mv,
              cpi->common.allow_high_precision_mv, x->errorperbit,
              &cpi->fn_ptr[bsize], cpi->sf.mv.subpel_force_stop,
              cpi->sf.mv.subpel_iters_per_step, cond_cost_list(cpi, cost_list),
              x->nmvjointcost, x->mvcost, &dis, &x->pred_sse[ref_frame], NULL, 0,
              0);
        } else if (svc->use_base_mv && svc->spatial_layer_id) {
          if (frame_mv[NEWMV][ref_frame].as_int != INVALID_MV) {
            const int pre_stride = xd->plane[0].pre[0].stride;
            unsigned int base_mv_sse = UINT_MAX;
            int scale = (cpi->rc.avg_frame_low_motion > 60) ? 2 : 4;
            const uint8_t *const pre_buf =
                xd->plane[0].pre[0].buf +
                (frame_mv[NEWMV][ref_frame].as_mv.row >> 3) * pre_stride +
                (frame_mv[NEWMV][ref_frame].as_mv.col >> 3);
            cpi->fn_ptr[bsize].vf(x->plane[0].src.buf, x->plane[0].src.stride,
                                  pre_buf, pre_stride, &base_mv_sse);
  
            // Exit NEWMV search if base_mv is (0,0) && bsize < BLOCK_16x16,
            // for SVC encoding.
            if (cpi->use_svc && svc->use_base_mv && bsize < BLOCK_16X16 &&
                frame_mv[NEWMV][ref_frame].as_mv.row == 0 &&
                frame_mv[NEWMV][ref_frame].as_mv.col == 0)
              continue;
  
            // Exit NEWMV search if base_mv_sse is large.
            if (sf->base_mv_aggressive && base_mv_sse > (best_sse_sofar << scale))
              continue;
            if (base_mv_sse < (best_sse_sofar << 1)) {
              // Base layer mv is good.
              // Exit NEWMV search if the base_mv is (0, 0) and sse is low, since
              // (0, 0) mode is already tested.
              unsigned int base_mv_sse_normalized =
                  base_mv_sse >>
                  (b_width_log2_lookup[bsize] + b_height_log2_lookup[bsize]);
              if (sf->base_mv_aggressive && base_mv_sse <= best_sse_sofar &&
                  base_mv_sse_normalized < 400 &&
                  frame_mv[NEWMV][ref_frame].as_mv.row == 0 &&
                  frame_mv[NEWMV][ref_frame].as_mv.col == 0)
                continue;
              if (!combined_motion_search(cpi, x, bsize, mi_row, mi_col,
                                          &frame_mv[NEWMV][ref_frame], &rate_mv,
                                          best_rdc.rdcost, 1)) {
                continue;
              }
            } else if (!combined_motion_search(cpi, x, bsize, mi_row, mi_col,
                                               &frame_mv[NEWMV][ref_frame],
                                               &rate_mv, best_rdc.rdcost, 0)) {
              continue;
            }
          } else if (!combined_motion_search(cpi, x, bsize, mi_row, mi_col,
                                             &frame_mv[NEWMV][ref_frame],
                                             &rate_mv, best_rdc.rdcost, 0)) {
            continue;
          }
        } else if (!combined_motion_search(cpi, x, bsize, mi_row, mi_col,
                                           &frame_mv[NEWMV][ref_frame], &rate_mv,
                                           best_rdc.rdcost, 0)) {
          continue;
        }
      }
  
      // TODO(jianj): Skipping the testing of (duplicate) non-zero motion vector
      // causes some regression, leave it for duplicate zero-mv for now, until
      // regression issue is resolved.
      for (inter_mv_mode = NEARESTMV; inter_mv_mode <= NEWMV; inter_mv_mode++) {
        if (inter_mv_mode == this_mode || comp_pred) continue;
        if (mode_checked[inter_mv_mode][ref_frame] &&
            frame_mv[this_mode][ref_frame].as_int ==
                frame_mv[inter_mv_mode][ref_frame].as_int &&
            frame_mv[inter_mv_mode][ref_frame].as_int == 0) {
          skip_this_mv = 1;
          break;
        }
      }
  
      if (skip_this_mv) continue;
  
      // If use_golden_nonzeromv is false, NEWMV mode is skipped for golden, no
      // need to compute best_pred_sad which is only used to skip golden NEWMV.
      if (use_golden_nonzeromv && this_mode == NEWMV && ref_frame == LAST_FRAME &&
          frame_mv[NEWMV][LAST_FRAME].as_int != INVALID_MV) {
        const int pre_stride = xd->plane[0].pre[0].stride;
        const uint8_t *const pre_buf =
            xd->plane[0].pre[0].buf +
            (frame_mv[NEWMV][LAST_FRAME].as_mv.row >> 3) * pre_stride +
            (frame_mv[NEWMV][LAST_FRAME].as_mv.col >> 3);
        best_pred_sad = cpi->fn_ptr[bsize].sdf(
            x->plane[0].src.buf, x->plane[0].src.stride, pre_buf, pre_stride);
        x->pred_mv_sad[LAST_FRAME] = best_pred_sad;
      }
  
      if (this_mode != NEARESTMV && !comp_pred &&
          frame_mv[this_mode][ref_frame].as_int ==
              frame_mv[NEARESTMV][ref_frame].as_int)
        continue;
  
      mi->mode = this_mode;
      mi->mv[0].as_int = frame_mv[this_mode][ref_frame].as_int;
      mi->mv[1].as_int = 0;
  
      // Search for the best prediction filter type, when the resulting
      // motion vector is at sub-pixel accuracy level for luma component, i.e.,
      // the last three bits are all zeros.
      if (reuse_inter_pred) {
        if (!this_mode_pred) {
          this_mode_pred = &tmp[3];
        } else {
          this_mode_pred = &tmp[get_pred_buffer(tmp, 3)];
          pd->dst.buf = this_mode_pred->data;
          pd->dst.stride = bw;
        }
      }
  
      if ((this_mode == NEWMV || filter_ref == SWITCHABLE) &&
          pred_filter_search &&
          (ref_frame == LAST_FRAME ||
           (ref_frame == GOLDEN_FRAME && !force_mv_inter_layer &&
            (cpi->use_svc || cpi->oxcf.rc_mode == VPX_VBR))) &&
          (((mi->mv[0].as_mv.row | mi->mv[0].as_mv.col) & 0x07) != 0)) {
        int pf_rate[3];
        int64_t pf_dist[3];
        int curr_rate[3];
        unsigned int pf_var[3];
        unsigned int pf_sse[3];
        TX_SIZE pf_tx_size[3];
        int64_t best_cost = INT64_MAX;
        INTERP_FILTER best_filter = SWITCHABLE, filter;
        PRED_BUFFER *current_pred = this_mode_pred;
        rd_computed = 1;
  
        for (filter = EIGHTTAP; filter <= EIGHTTAP_SMOOTH; ++filter) {
          int64_t cost;
          mi->interp_filter = filter;
          vp9_build_inter_predictors_sby(xd, mi_row, mi_col, bsize);
          model_rd_for_sb_y(cpi, bsize, x, xd, &pf_rate[filter], &pf_dist[filter],
                            &pf_var[filter], &pf_sse[filter]);
          curr_rate[filter] = pf_rate[filter];
          pf_rate[filter] += vp9_get_switchable_rate(cpi, xd);
          cost = RDCOST(x->rdmult, x->rddiv, pf_rate[filter], pf_dist[filter]);
          pf_tx_size[filter] = mi->tx_size;
          if (cost < best_cost) {
            best_filter = filter;
            best_cost = cost;
            skip_txfm = x->skip_txfm[0];
  
            if (reuse_inter_pred) {
              if (this_mode_pred != current_pred) {
                free_pred_buffer(this_mode_pred);
                this_mode_pred = current_pred;
              }
              current_pred = &tmp[get_pred_buffer(tmp, 3)];
              pd->dst.buf = current_pred->data;
              pd->dst.stride = bw;
            }
          }
        }
  
        if (reuse_inter_pred && this_mode_pred != current_pred)
          free_pred_buffer(current_pred);
  
        mi->interp_filter = best_filter;
        mi->tx_size = pf_tx_size[best_filter];
        this_rdc.rate = curr_rate[best_filter];
        this_rdc.dist = pf_dist[best_filter];
        var_y = pf_var[best_filter];
        sse_y = pf_sse[best_filter];
        x->skip_txfm[0] = skip_txfm;
        if (reuse_inter_pred) {
          pd->dst.buf = this_mode_pred->data;
          pd->dst.stride = this_mode_pred->stride;
        }
      } else {
        // For low motion content use x->sb_is_skin in addition to VeryHighSad
        // for setting large_block.
        const int large_block =
            (x->content_state_sb == kVeryHighSad ||
             (x->sb_is_skin && cpi->rc.avg_frame_low_motion > 70) ||
             cpi->oxcf.speed < 7)
                ? bsize > BLOCK_32X32
                : bsize >= BLOCK_32X32;
        mi->interp_filter = (filter_ref == SWITCHABLE) ? EIGHTTAP : filter_ref;
  
        if (cpi->use_svc && ref_frame == GOLDEN_FRAME &&
            svc_force_zero_mode[ref_frame - 1])
          mi->interp_filter = filter_gf_svc;
  
        vp9_build_inter_predictors_sby(xd, mi_row, mi_col, bsize);
  
        // For large partition blocks, extra testing is done.
        if (cpi->oxcf.rc_mode == VPX_CBR && large_block &&
            !cyclic_refresh_segment_id_boosted(xd->mi[0]->segment_id) &&
            cm->base_qindex) {
          model_rd_for_sb_y_large(cpi, bsize, x, xd, &this_rdc.rate,
                                  &this_rdc.dist, &var_y, &sse_y, mi_row, mi_col,
                                  &this_early_term, flag_preduv_computed);
        } else {
          rd_computed = 1;
          model_rd_for_sb_y(cpi, bsize, x, xd, &this_rdc.rate, &this_rdc.dist,
                            &var_y, &sse_y);
        }
        // Save normalized sse (between current and last frame) for (0, 0) motion.
        if (cpi->use_svc && ref_frame == LAST_FRAME &&
            frame_mv[this_mode][ref_frame].as_int == 0) {
          sse_zeromv_normalized =
              sse_y >> (b_width_log2_lookup[bsize] + b_height_log2_lookup[bsize]);
        }
        if (sse_y < best_sse_sofar) best_sse_sofar = sse_y;
      }
  
      if (!this_early_term) {
        this_sse = (int64_t)sse_y;
        block_yrd(cpi, x, &this_rdc, &is_skippable, &this_sse, bsize,
                  VPXMIN(mi->tx_size, TX_16X16), rd_computed);
  
        x->skip_txfm[0] = is_skippable;
        if (is_skippable) {
          this_rdc.rate = vp9_cost_bit(vp9_get_skip_prob(cm, xd), 1);
        } else {
          if (RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist) <
              RDCOST(x->rdmult, x->rddiv, 0, this_sse)) {
            this_rdc.rate += vp9_cost_bit(vp9_get_skip_prob(cm, xd), 0);
          } else {
            this_rdc.rate = vp9_cost_bit(vp9_get_skip_prob(cm, xd), 1);
            this_rdc.dist = this_sse;
            x->skip_txfm[0] = SKIP_TXFM_AC_DC;
          }
        }
  
        if (cm->interp_filter == SWITCHABLE) {
          if ((mi->mv[0].as_mv.row | mi->mv[0].as_mv.col) & 0x07)
            this_rdc.rate += vp9_get_switchable_rate(cpi, xd);
        }
      } else {
        this_rdc.rate += cm->interp_filter == SWITCHABLE
                             ? vp9_get_switchable_rate(cpi, xd)
                             : 0;
        this_rdc.rate += vp9_cost_bit(vp9_get_skip_prob(cm, xd), 1);
      }
  
      if (!this_early_term &&
          (x->color_sensitivity[0] || x->color_sensitivity[1])) {
        RD_COST rdc_uv;
        const BLOCK_SIZE uv_bsize = get_plane_block_size(bsize, &xd->plane[1]);
        if (x->color_sensitivity[0] && !flag_preduv_computed[0]) {
          vp9_build_inter_predictors_sbp(xd, mi_row, mi_col, bsize, 1);
          flag_preduv_computed[0] = 1;
        }
        if (x->color_sensitivity[1] && !flag_preduv_computed[1]) {
          vp9_build_inter_predictors_sbp(xd, mi_row, mi_col, bsize, 2);
          flag_preduv_computed[1] = 1;
        }
        model_rd_for_sb_uv(cpi, uv_bsize, x, xd, &rdc_uv, &var_y, &sse_y, 1, 2);
        this_rdc.rate += rdc_uv.rate;
        this_rdc.dist += rdc_uv.dist;
      }
  
      this_rdc.rate += rate_mv;
      this_rdc.rate += cpi->inter_mode_cost[x->mbmi_ext->mode_context[ref_frame]]
                                           [INTER_OFFSET(this_mode)];
      // TODO(marpan): Add costing for compound mode.
      this_rdc.rate += ref_frame_cost[ref_frame];
      this_rdc.rdcost = RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist);
  
      // Bias against NEWMV that is very different from its neighbors, and bias
      // to small motion-lastref for noisy input.
      if (cpi->oxcf.rc_mode == VPX_CBR && cpi->oxcf.speed >= 5 &&
          cpi->oxcf.content != VP9E_CONTENT_SCREEN) {
        vp9_NEWMV_diff_bias(&cpi->noise_estimate, xd, this_mode, &this_rdc, bsize,
                            frame_mv[this_mode][ref_frame].as_mv.row,
                            frame_mv[this_mode][ref_frame].as_mv.col,
                            ref_frame == LAST_FRAME, x->lowvar_highsumdiff,
                            x->sb_is_skin);
      }
  
      // Skipping checking: test to see if this block can be reconstructed by
      // prediction only.
      if (cpi->allow_encode_breakout) {
        encode_breakout_test(cpi, x, bsize, mi_row, mi_col, ref_frame, this_mode,
                             var_y, sse_y, yv12_mb, &this_rdc.rate,
                             &this_rdc.dist, flag_preduv_computed);
        if (x->skip) {
          this_rdc.rate += rate_mv;
          this_rdc.rdcost =
              RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist);
        }
      }
  
  #if CONFIG_VP9_TEMPORAL_DENOISING
      if (cpi->oxcf.noise_sensitivity > 0 && denoise_svc_pickmode &&
          cpi->denoiser.denoising_level > kDenLowLow) {
        vp9_denoiser_update_frame_stats(mi, sse_y, this_mode, ctx);
        // Keep track of zero_last cost.
        if (ref_frame == LAST_FRAME && frame_mv[this_mode][ref_frame].as_int == 0)
          zero_last_cost_orig = this_rdc.rdcost;
      }
  #else
      (void)ctx;
  #endif
  
      mode_checked[this_mode][ref_frame] = 1;
  
      if (this_rdc.rdcost < best_rdc.rdcost || x->skip) {
        best_rdc = this_rdc;
        best_mode = this_mode;
        best_pred_filter = mi->interp_filter;
        best_tx_size = mi->tx_size;
        best_ref_frame = ref_frame;
        best_mode_skip_txfm = x->skip_txfm[0];
        best_early_term = this_early_term;
        best_second_ref_frame = second_ref_frame;
  
        if (reuse_inter_pred) {
          free_pred_buffer(best_pred);
          best_pred = this_mode_pred;
        }
      } else {
        if (reuse_inter_pred) free_pred_buffer(this_mode_pred);
      }
  
      if (x->skip) break;
  
      // If early termination flag is 1 and at least 2 modes are checked,
      // the mode search is terminated.
      if (best_early_term && idx > 0) {
        x->skip = 1;
        break;
      }
    }
  
    mi->mode = best_mode;
    mi->interp_filter = best_pred_filter;
    mi->tx_size = best_tx_size;
    mi->ref_frame[0] = best_ref_frame;
    mi->mv[0].as_int = frame_mv[best_mode][best_ref_frame].as_int;
    xd->mi[0]->bmi[0].as_mv[0].as_int = mi->mv[0].as_int;
    x->skip_txfm[0] = best_mode_skip_txfm;
    mi->ref_frame[1] = best_second_ref_frame;
  
    // For spatial enhancemanent layer: perform intra prediction only if base
    // layer is chosen as the reference. Always perform intra prediction if
    // LAST is the only reference, or is_key_frame is set, or on base
    // temporal layer.
    if (svc->spatial_layer_id && !gf_is_longterm_ref) {
      perform_intra_pred =
          svc->temporal_layer_id == 0 ||
          svc->layer_context[svc->temporal_layer_id].is_key_frame ||
          !(cpi->ref_frame_flags & flag_list[GOLDEN_FRAME]) ||
          (!svc->layer_context[svc->temporal_layer_id].is_key_frame &&
           svc_force_zero_mode[best_ref_frame - 1]);
      inter_mode_thresh = (inter_mode_thresh << 1) + inter_mode_thresh;
    }
    if (cpi->oxcf.lag_in_frames > 0 && cpi->oxcf.rc_mode == VPX_VBR &&
        cpi->rc.is_src_frame_alt_ref)
      perform_intra_pred = 0;
  
    // If the segment reference frame feature is enabled and set then
    // skip the intra prediction.
    if (segfeature_active(seg, mi->segment_id, SEG_LVL_REF_FRAME) &&
        get_segdata(seg, mi->segment_id, SEG_LVL_REF_FRAME) > 0)
      perform_intra_pred = 0;
  
    // Perform intra prediction search, if the best SAD is above a certain
    // threshold.
    if (best_rdc.rdcost == INT64_MAX ||
        ((!force_skip_low_temp_var || bsize < BLOCK_32X32 ||
          x->content_state_sb == kVeryHighSad) &&
         perform_intra_pred && !x->skip && best_rdc.rdcost > inter_mode_thresh &&
         bsize <= cpi->sf.max_intra_bsize && !x->skip_low_source_sad &&
         !x->lowvar_highsumdiff)) {
      struct estimate_block_intra_args args = { cpi, x, DC_PRED, 1, 0 };
      int i;
      TX_SIZE best_intra_tx_size = TX_SIZES;
      TX_SIZE intra_tx_size =
          VPXMIN(max_txsize_lookup[bsize],
                 tx_mode_to_biggest_tx_size[cpi->common.tx_mode]);
      if (cpi->oxcf.content != VP9E_CONTENT_SCREEN && intra_tx_size > TX_16X16)
        intra_tx_size = TX_16X16;
  
      if (reuse_inter_pred && best_pred != NULL) {
        if (best_pred->data == orig_dst.buf) {
          this_mode_pred = &tmp[get_pred_buffer(tmp, 3)];
  #if CONFIG_VP9_HIGHBITDEPTH
          if (cm->use_highbitdepth)
            vpx_highbd_convolve_copy(
                CONVERT_TO_SHORTPTR(best_pred->data), best_pred->stride,
                CONVERT_TO_SHORTPTR(this_mode_pred->data), this_mode_pred->stride,
                NULL, 0, 0, 0, 0, bw, bh, xd->bd);
          else
            vpx_convolve_copy(best_pred->data, best_pred->stride,
                              this_mode_pred->data, this_mode_pred->stride, NULL,
                              0, 0, 0, 0, bw, bh);
  #else
          vpx_convolve_copy(best_pred->data, best_pred->stride,
                            this_mode_pred->data, this_mode_pred->stride, NULL, 0,
                            0, 0, 0, bw, bh);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
          best_pred = this_mode_pred;
        }
      }
      pd->dst = orig_dst;
  
      for (i = 0; i < 4; ++i) {
        const PREDICTION_MODE this_mode = intra_mode_list[i];
        THR_MODES mode_index = mode_idx[INTRA_FRAME][mode_offset(this_mode)];
        int mode_rd_thresh = rd_threshes[mode_index];
        if (sf->short_circuit_flat_blocks && x->source_variance == 0 &&
            this_mode != DC_PRED) {
          continue;
        }
  
        if (!((1 << this_mode) & cpi->sf.intra_y_mode_bsize_mask[bsize]))
          continue;
  
        if ((cpi->sf.adaptive_rd_thresh_row_mt &&
             rd_less_than_thresh_row_mt(best_rdc.rdcost, mode_rd_thresh,
                                        &rd_thresh_freq_fact[mode_index])) ||
            (!cpi->sf.adaptive_rd_thresh_row_mt &&
             rd_less_than_thresh(best_rdc.rdcost, mode_rd_thresh,
                                 &rd_thresh_freq_fact[mode_index])))
          continue;
  
        mi->mode = this_mode;
        mi->ref_frame[0] = INTRA_FRAME;
        this_rdc.dist = this_rdc.rate = 0;
        args.mode = this_mode;
        args.skippable = 1;
        args.rdc = &this_rdc;
        mi->tx_size = intra_tx_size;
        vp9_foreach_transformed_block_in_plane(xd, bsize, 0, estimate_block_intra,
                                               &args);
        // Check skip cost here since skippable is not set for for uv, this
        // mirrors the behavior used by inter
        if (args.skippable) {
          x->skip_txfm[0] = SKIP_TXFM_AC_DC;
          this_rdc.rate = vp9_cost_bit(vp9_get_skip_prob(&cpi->common, xd), 1);
        } else {
          x->skip_txfm[0] = SKIP_TXFM_NONE;
          this_rdc.rate += vp9_cost_bit(vp9_get_skip_prob(&cpi->common, xd), 0);
        }
        // Inter and intra RD will mismatch in scale for non-screen content.
        if (cpi->oxcf.content == VP9E_CONTENT_SCREEN) {
          if (x->color_sensitivity[0])
            vp9_foreach_transformed_block_in_plane(xd, bsize, 1,
                                                   estimate_block_intra, &args);
          if (x->color_sensitivity[1])
            vp9_foreach_transformed_block_in_plane(xd, bsize, 2,
                                                   estimate_block_intra, &args);
        }
        this_rdc.rate += cpi->mbmode_cost[this_mode];
        this_rdc.rate += ref_frame_cost[INTRA_FRAME];
        this_rdc.rate += intra_cost_penalty;
        this_rdc.rdcost =
            RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist);
  
        if (this_rdc.rdcost < best_rdc.rdcost) {
          best_rdc = this_rdc;
          best_mode = this_mode;
          best_intra_tx_size = mi->tx_size;
          best_ref_frame = INTRA_FRAME;
          best_second_ref_frame = NONE;
          mi->uv_mode = this_mode;
          mi->mv[0].as_int = INVALID_MV;
          mi->mv[1].as_int = INVALID_MV;
          best_mode_skip_txfm = x->skip_txfm[0];
        }
      }
  
      // Reset mb_mode_info to the best inter mode.
      if (best_ref_frame != INTRA_FRAME) {
        mi->tx_size = best_tx_size;
      } else {
        mi->tx_size = best_intra_tx_size;
      }
    }
  
    pd->dst = orig_dst;
    mi->mode = best_mode;
    mi->ref_frame[0] = best_ref_frame;
    mi->ref_frame[1] = best_second_ref_frame;
    x->skip_txfm[0] = best_mode_skip_txfm;
  
    if (!is_inter_block(mi)) {
      mi->interp_filter = SWITCHABLE_FILTERS;
    }
  
    if (reuse_inter_pred && best_pred != NULL) {
      if (best_pred->data != orig_dst.buf && is_inter_mode(mi->mode)) {
  #if CONFIG_VP9_HIGHBITDEPTH
        if (cm->use_highbitdepth)
          vpx_highbd_convolve_copy(
              CONVERT_TO_SHORTPTR(best_pred->data), best_pred->stride,
              CONVERT_TO_SHORTPTR(pd->dst.buf), pd->dst.stride, NULL, 0, 0, 0, 0,
              bw, bh, xd->bd);
        else
          vpx_convolve_copy(best_pred->data, best_pred->stride, pd->dst.buf,
                            pd->dst.stride, NULL, 0, 0, 0, 0, bw, bh);
  #else
        vpx_convolve_copy(best_pred->data, best_pred->stride, pd->dst.buf,
                          pd->dst.stride, NULL, 0, 0, 0, 0, bw, bh);
  #endif  // CONFIG_VP9_HIGHBITDEPTH
      }
    }
  
  #if CONFIG_VP9_TEMPORAL_DENOISING
    if (cpi->oxcf.noise_sensitivity > 0 && cpi->resize_pending == 0 &&
        denoise_svc_pickmode && cpi->denoiser.denoising_level > kDenLowLow &&
        cpi->denoiser.reset == 0) {
      VP9_DENOISER_DECISION decision = COPY_BLOCK;
      ctx->sb_skip_denoising = 0;
      // TODO(marpan): There is an issue with denoising when the
      // superblock partitioning scheme is based on the pickmode.
      // Remove this condition when the issue is resolved.
      if (x->sb_pickmode_part) ctx->sb_skip_denoising = 1;
      vp9_pickmode_ctx_den_update(&ctx_den, zero_last_cost_orig, ref_frame_cost,
                                  frame_mv, reuse_inter_pred, best_tx_size,
                                  best_mode, best_ref_frame, best_pred_filter,
                                  best_mode_skip_txfm);
      vp9_denoiser_denoise(cpi, x, mi_row, mi_col, bsize, ctx, &decision);
      recheck_zeromv_after_denoising(cpi, mi, x, xd, decision, &ctx_den, yv12_mb,
                                     &best_rdc, bsize, mi_row, mi_col);
      best_ref_frame = ctx_den.best_ref_frame;
    }
  #endif
  
    if (best_ref_frame == ALTREF_FRAME || best_second_ref_frame == ALTREF_FRAME)
      x->arf_frame_usage++;
    else if (best_ref_frame != INTRA_FRAME)
      x->lastgolden_frame_usage++;
  
    if (cpi->sf.adaptive_rd_thresh) {
      THR_MODES best_mode_idx = mode_idx[best_ref_frame][mode_offset(mi->mode)];
  
      if (best_ref_frame == INTRA_FRAME) {
        // Only consider the modes that are included in the intra_mode_list.
        int intra_modes = sizeof(intra_mode_list) / sizeof(PREDICTION_MODE);
        int i;
  
        // TODO(yunqingwang): Check intra mode mask and only update freq_fact
        // for those valid modes.
        for (i = 0; i < intra_modes; i++) {
          if (cpi->sf.adaptive_rd_thresh_row_mt)
            update_thresh_freq_fact_row_mt(cpi, tile_data, x->source_variance,
                                           thresh_freq_fact_idx, INTRA_FRAME,
                                           best_mode_idx, intra_mode_list[i]);
          else
            update_thresh_freq_fact(cpi, tile_data, x->source_variance, bsize,
                                    INTRA_FRAME, best_mode_idx,
                                    intra_mode_list[i]);
        }
      } else {
        for (ref_frame = LAST_FRAME; ref_frame <= GOLDEN_FRAME; ++ref_frame) {
          PREDICTION_MODE this_mode;
          if (best_ref_frame != ref_frame) continue;
          for (this_mode = NEARESTMV; this_mode <= NEWMV; ++this_mode) {
            if (cpi->sf.adaptive_rd_thresh_row_mt)
              update_thresh_freq_fact_row_mt(cpi, tile_data, x->source_variance,
                                             thresh_freq_fact_idx, ref_frame,
                                             best_mode_idx, this_mode);
            else
              update_thresh_freq_fact(cpi, tile_data, x->source_variance, bsize,
                                      ref_frame, best_mode_idx, this_mode);
          }
        }
      }
    }
  
    *rd_cost = best_rdc;
  }
  
  void vp9_pick_inter_mode_sub8x8(VP9_COMP *cpi, MACROBLOCK *x, int mi_row,
                                  int mi_col, RD_COST *rd_cost, BLOCK_SIZE bsize,
                                  PICK_MODE_CONTEXT *ctx) {
    VP9_COMMON *const cm = &cpi->common;
    SPEED_FEATURES *const sf = &cpi->sf;
    MACROBLOCKD *const xd = &x->e_mbd;
    MODE_INFO *const mi = xd->mi[0];
    MB_MODE_INFO_EXT *const mbmi_ext = x->mbmi_ext;
    const struct segmentation *const seg = &cm->seg;
    MV_REFERENCE_FRAME ref_frame, second_ref_frame = NONE;
    MV_REFERENCE_FRAME best_ref_frame = NONE;
    unsigned char segment_id = mi->segment_id;
    struct buf_2d yv12_mb[4][MAX_MB_PLANE];
    static const int flag_list[4] = { 0, VP9_LAST_FLAG, VP9_GOLD_FLAG,
                                      VP9_ALT_FLAG };
    int64_t best_rd = INT64_MAX;
    b_mode_info bsi[MAX_REF_FRAMES][4];
    int ref_frame_skip_mask = 0;
    const int num_4x4_blocks_wide = num_4x4_blocks_wide_lookup[bsize];
    const int num_4x4_blocks_high = num_4x4_blocks_high_lookup[bsize];
    int idx, idy;
  
    x->skip_encode = sf->skip_encode_frame && x->q_index < QIDX_SKIP_THRESH;
    ctx->pred_pixel_ready = 0;
  
    for (ref_frame = LAST_FRAME; ref_frame <= GOLDEN_FRAME; ++ref_frame) {
      const YV12_BUFFER_CONFIG *yv12 = get_ref_frame_buffer(cpi, ref_frame);
      int_mv dummy_mv[2];
      x->pred_mv_sad[ref_frame] = INT_MAX;
  
      if ((cpi->ref_frame_flags & flag_list[ref_frame]) && (yv12 != NULL)) {
        int_mv *const candidates = mbmi_ext->ref_mvs[ref_frame];
        const struct scale_factors *const sf = &cm->frame_refs[ref_frame - 1].sf;
        vp9_setup_pred_block(xd, yv12_mb[ref_frame], yv12, mi_row, mi_col, sf,
                             sf);
        vp9_find_mv_refs(cm, xd, xd->mi[0], ref_frame, candidates, mi_row, mi_col,
                         mbmi_ext->mode_context);
  
        vp9_find_best_ref_mvs(xd, cm->allow_high_precision_mv, candidates,
                              &dummy_mv[0], &dummy_mv[1]);
      } else {
        ref_frame_skip_mask |= (1 << ref_frame);
      }
    }
  
    mi->sb_type = bsize;
    mi->tx_size = TX_4X4;
    mi->uv_mode = DC_PRED;
    mi->ref_frame[0] = LAST_FRAME;
    mi->ref_frame[1] = NONE;
    mi->interp_filter =
        cm->interp_filter == SWITCHABLE ? EIGHTTAP : cm->interp_filter;
  
    for (ref_frame = LAST_FRAME; ref_frame <= GOLDEN_FRAME; ++ref_frame) {
      int64_t this_rd = 0;
      int plane;
  
      if (ref_frame_skip_mask & (1 << ref_frame)) continue;
  
  #if CONFIG_BETTER_HW_COMPATIBILITY
      if ((bsize == BLOCK_8X4 || bsize == BLOCK_4X8) && ref_frame > INTRA_FRAME &&
          vp9_is_scaled(&cm->frame_refs[ref_frame - 1].sf))
        continue;
  #endif
  
      // TODO(jingning, agrange): Scaling reference frame not supported for
      // sub8x8 blocks. Is this supported now?
      if (ref_frame > INTRA_FRAME &&
          vp9_is_scaled(&cm->frame_refs[ref_frame - 1].sf))
        continue;
  
      // If the segment reference frame feature is enabled....
      // then do nothing if the current ref frame is not allowed..
      if (segfeature_active(seg, segment_id, SEG_LVL_REF_FRAME) &&
          get_segdata(seg, segment_id, SEG_LVL_REF_FRAME) != (int)ref_frame)
        continue;
  
      mi->ref_frame[0] = ref_frame;
      x->skip = 0;
      set_ref_ptrs(cm, xd, ref_frame, second_ref_frame);
  
      // Select prediction reference frames.
      for (plane = 0; plane < MAX_MB_PLANE; plane++)
        xd->plane[plane].pre[0] = yv12_mb[ref_frame][plane];
  
      for (idy = 0; idy < 2; idy += num_4x4_blocks_high) {
        for (idx = 0; idx < 2; idx += num_4x4_blocks_wide) {
          int_mv b_mv[MB_MODE_COUNT];
          int64_t b_best_rd = INT64_MAX;
          const int i = idy * 2 + idx;
          PREDICTION_MODE this_mode;
          RD_COST this_rdc;
          unsigned int var_y, sse_y;
  
          struct macroblock_plane *p = &x->plane[0];
          struct macroblockd_plane *pd = &xd->plane[0];
  
          const struct buf_2d orig_src = p->src;
          const struct buf_2d orig_dst = pd->dst;
          struct buf_2d orig_pre[2];
          memcpy(orig_pre, xd->plane[0].pre, sizeof(orig_pre));
  
          // set buffer pointers for sub8x8 motion search.
          p->src.buf =
              &p->src.buf[vp9_raster_block_offset(BLOCK_8X8, i, p->src.stride)];
          pd->dst.buf =
              &pd->dst.buf[vp9_raster_block_offset(BLOCK_8X8, i, pd->dst.stride)];
          pd->pre[0].buf =
              &pd->pre[0]
                   .buf[vp9_raster_block_offset(BLOCK_8X8, i, pd->pre[0].stride)];
  
          b_mv[ZEROMV].as_int = 0;
          b_mv[NEWMV].as_int = INVALID_MV;
          vp9_append_sub8x8_mvs_for_idx(cm, xd, i, 0, mi_row, mi_col,
                                        &b_mv[NEARESTMV], &b_mv[NEARMV],
                                        mbmi_ext->mode_context);
  
          for (this_mode = NEARESTMV; this_mode <= NEWMV; ++this_mode) {
            int b_rate = 0;
            xd->mi[0]->bmi[i].as_mv[0].as_int = b_mv[this_mode].as_int;
  
            if (this_mode == NEWMV) {
              const int step_param = cpi->sf.mv.fullpel_search_step_param;
              MV mvp_full;
              MV tmp_mv;
              int cost_list[5];
              const MvLimits tmp_mv_limits = x->mv_limits;
              uint32_t dummy_dist;
  
              if (i == 0) {
                mvp_full.row = b_mv[NEARESTMV].as_mv.row >> 3;
                mvp_full.col = b_mv[NEARESTMV].as_mv.col >> 3;
              } else {
                mvp_full.row = xd->mi[0]->bmi[0].as_mv[0].as_mv.row >> 3;
                mvp_full.col = xd->mi[0]->bmi[0].as_mv[0].as_mv.col >> 3;
              }
  
              vp9_set_mv_search_range(&x->mv_limits,
                                      &mbmi_ext->ref_mvs[ref_frame][0].as_mv);
  
              vp9_full_pixel_search(
                  cpi, x, bsize, &mvp_full, step_param, cpi->sf.mv.search_method,
                  x->sadperbit4, cond_cost_list(cpi, cost_list),
                  &mbmi_ext->ref_mvs[ref_frame][0].as_mv, &tmp_mv, INT_MAX, 0);
  
              x->mv_limits = tmp_mv_limits;
  
              // calculate the bit cost on motion vector
              mvp_full.row = tmp_mv.row * 8;
              mvp_full.col = tmp_mv.col * 8;
  
              b_rate += vp9_mv_bit_cost(
                  &mvp_full, &mbmi_ext->ref_mvs[ref_frame][0].as_mv,
                  x->nmvjointcost, x->mvcost, MV_COST_WEIGHT);
  
              b_rate += cpi->inter_mode_cost[x->mbmi_ext->mode_context[ref_frame]]
                                            [INTER_OFFSET(NEWMV)];
              if (RDCOST(x->rdmult, x->rddiv, b_rate, 0) > b_best_rd) continue;
  
              cpi->find_fractional_mv_step(
                  x, &tmp_mv, &mbmi_ext->ref_mvs[ref_frame][0].as_mv,
                  cpi->common.allow_high_precision_mv, x->errorperbit,
                  &cpi->fn_ptr[bsize], cpi->sf.mv.subpel_force_stop,
                  cpi->sf.mv.subpel_iters_per_step,
                  cond_cost_list(cpi, cost_list), x->nmvjointcost, x->mvcost,
                  &dummy_dist, &x->pred_sse[ref_frame], NULL, 0, 0);
  
              xd->mi[0]->bmi[i].as_mv[0].as_mv = tmp_mv;
            } else {
              b_rate += cpi->inter_mode_cost[x->mbmi_ext->mode_context[ref_frame]]
                                            [INTER_OFFSET(this_mode)];
            }
  
  #if CONFIG_VP9_HIGHBITDEPTH
            if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
              vp9_highbd_build_inter_predictor(
                  CONVERT_TO_SHORTPTR(pd->pre[0].buf), pd->pre[0].stride,
                  CONVERT_TO_SHORTPTR(pd->dst.buf), pd->dst.stride,
                  &xd->mi[0]->bmi[i].as_mv[0].as_mv, &xd->block_refs[0]->sf,
                  4 * num_4x4_blocks_wide, 4 * num_4x4_blocks_high, 0,
                  vp9_filter_kernels[mi->interp_filter], MV_PRECISION_Q3,
                  mi_col * MI_SIZE + 4 * (i & 0x01),
                  mi_row * MI_SIZE + 4 * (i >> 1), xd->bd);
            } else {
  #endif
              vp9_build_inter_predictor(
                  pd->pre[0].buf, pd->pre[0].stride, pd->dst.buf, pd->dst.stride,
                  &xd->mi[0]->bmi[i].as_mv[0].as_mv, &xd->block_refs[0]->sf,
                  4 * num_4x4_blocks_wide, 4 * num_4x4_blocks_high, 0,
                  vp9_filter_kernels[mi->interp_filter], MV_PRECISION_Q3,
                  mi_col * MI_SIZE + 4 * (i & 0x01),
                  mi_row * MI_SIZE + 4 * (i >> 1));
  
  #if CONFIG_VP9_HIGHBITDEPTH
            }
  #endif
  
            model_rd_for_sb_y(cpi, bsize, x, xd, &this_rdc.rate, &this_rdc.dist,
                              &var_y, &sse_y);
  
            this_rdc.rate += b_rate;
            this_rdc.rdcost =
                RDCOST(x->rdmult, x->rddiv, this_rdc.rate, this_rdc.dist);
            if (this_rdc.rdcost < b_best_rd) {
              b_best_rd = this_rdc.rdcost;
              bsi[ref_frame][i].as_mode = this_mode;
              bsi[ref_frame][i].as_mv[0].as_mv = xd->mi[0]->bmi[i].as_mv[0].as_mv;
            }
          }  // mode search
  
          // restore source and prediction buffer pointers.
          p->src = orig_src;
          pd->pre[0] = orig_pre[0];
          pd->dst = orig_dst;
          this_rd += b_best_rd;
  
          xd->mi[0]->bmi[i] = bsi[ref_frame][i];
          if (num_4x4_blocks_wide > 1) xd->mi[0]->bmi[i + 1] = xd->mi[0]->bmi[i];
          if (num_4x4_blocks_high > 1) xd->mi[0]->bmi[i + 2] = xd->mi[0]->bmi[i];
        }
      }  // loop through sub8x8 blocks
  
      if (this_rd < best_rd) {
        best_rd = this_rd;
        best_ref_frame = ref_frame;
      }
    }  // reference frames
  
    mi->tx_size = TX_4X4;
    mi->ref_frame[0] = best_ref_frame;
    for (idy = 0; idy < 2; idy += num_4x4_blocks_high) {
      for (idx = 0; idx < 2; idx += num_4x4_blocks_wide) {
        const int block = idy * 2 + idx;
        xd->mi[0]->bmi[block] = bsi[best_ref_frame][block];
        if (num_4x4_blocks_wide > 1)
          xd->mi[0]->bmi[block + 1] = bsi[best_ref_frame][block];
        if (num_4x4_blocks_high > 1)
          xd->mi[0]->bmi[block + 2] = bsi[best_ref_frame][block];
      }
    }
    mi->mode = xd->mi[0]->bmi[3].as_mode;
    ctx->mic = *(xd->mi[0]);
    ctx->mbmi_ext = *x->mbmi_ext;
    ctx->skip_txfm[0] = SKIP_TXFM_NONE;
    ctx->skip = 0;
    // Dummy assignment for speed -5. No effect in speed -6.
    rd_cost->rdcost = best_rd;
  }
  