vp9_encodeframe.c

      }
    }

    vp9_zero(cpi->mb.pred_mv);

    if ((cpi->sf.partition_search_type == SEARCH_PARTITION &&
         cpi->sf.use_lastframe_partitioning) ||
        cpi->sf.partition_search_type == FIXED_PARTITION ||
        cpi->sf.partition_search_type == VAR_BASED_FIXED_PARTITION) {
      const int idx_str = cm->mode_info_stride * mi_row + mi_col;
      MODE_INFO **mi_8x8 = cm->mi_grid_visible + idx_str;
      MODE_INFO **prev_mi_8x8 = cm->prev_mi_grid_visible + idx_str;

      cpi->mb.source_variance = UINT_MAX;
      if (cpi->sf.partition_search_type == FIXED_PARTITION) {
        set_offsets(cpi, tile, mi_row, mi_col, BLOCK_64X64);
        set_partitioning(cpi, tile, mi_8x8, mi_row, mi_col,
                         cpi->sf.always_this_block_size);
        rd_use_partition(cpi, tile, mi_8x8, tp, mi_row, mi_col, BLOCK_64X64,
                         &dummy_rate, &dummy_dist, 1);
      } else if (cpi->sf.partition_search_type == VAR_BASED_FIXED_PARTITION ||
                 cpi->sf.partition_search_type == VAR_BASED_PARTITION) {
        // TODO(debargha): Implement VAR_BASED_PARTITION as a separate case.
        // Currently both VAR_BASED_FIXED_PARTITION/VAR_BASED_PARTITION
        // map to the same thing.
        BLOCK_SIZE bsize;
        set_offsets(cpi, tile, mi_row, mi_col, BLOCK_64X64);
        bsize = get_rd_var_based_fixed_partition(cpi, mi_row, mi_col);
        set_partitioning(cpi, tile, mi_8x8, mi_row, mi_col, bsize);
        rd_use_partition(cpi, tile, mi_8x8, tp, mi_row, mi_col, BLOCK_64X64,
                         &dummy_rate, &dummy_dist, 1);
      } else {
        if ((cm->current_video_frame
            % cpi->sf.last_partitioning_redo_frequency) == 0
            || cm->prev_mi == 0
            || cm->show_frame == 0
            || cm->frame_type == KEY_FRAME
            || cpi->rc.is_src_frame_alt_ref
            || ((cpi->sf.use_lastframe_partitioning ==
                 LAST_FRAME_PARTITION_LOW_MOTION) &&
                 sb_has_motion(cm, prev_mi_8x8))) {
          // If required set upper and lower partition size limits
          if (cpi->sf.auto_min_max_partition_size) {
            set_offsets(cpi, tile, mi_row, mi_col, BLOCK_64X64);
            rd_auto_partition_range(cpi, tile, mi_row, mi_col,
                                    &cpi->sf.min_partition_size,
                                    &cpi->sf.max_partition_size);
          }
          rd_pick_partition(cpi, tile, tp, mi_row, mi_col, BLOCK_64X64,
                            &dummy_rate, &dummy_dist, 1, INT64_MAX);
        } else {
          copy_partitioning(cm, mi_8x8, prev_mi_8x8);
          rd_use_partition(cpi, tile, mi_8x8, tp, mi_row, mi_col, BLOCK_64X64,
                           &dummy_rate, &dummy_dist, 1);
        }
      }
    } else {
      // If required set upper and lower partition size limits
      if (cpi->sf.auto_min_max_partition_size) {
        set_offsets(cpi, tile, mi_row, mi_col, BLOCK_64X64);
        rd_auto_partition_range(cpi, tile, mi_row, mi_col,
                                &cpi->sf.min_partition_size,
                                &cpi->sf.max_partition_size);
      }
      rd_pick_partition(cpi, tile, tp, mi_row, mi_col, BLOCK_64X64,
                        &dummy_rate, &dummy_dist, 1, INT64_MAX);
    }
  }
}

static void init_encode_frame_mb_context(VP9_COMP *cpi) {
  MACROBLOCK *const x = &cpi->mb;
  VP9_COMMON *const cm = &cpi->common;
  MACROBLOCKD *const xd = &x->e_mbd;
  const int aligned_mi_cols = mi_cols_aligned_to_sb(cm->mi_cols);

  x->act_zbin_adj = 0;
  cpi->seg0_idx = 0;

  xd->mode_info_stride = cm->mode_info_stride;

  // Copy data over into macro block data structures.
  vp9_setup_src_planes(x, cpi->Source, 0, 0);

  // TODO(jkoleszar): are these initializations required?
  setup_pre_planes(xd, 0, get_ref_frame_buffer(cpi, LAST_FRAME), 0, 0, NULL);
  setup_dst_planes(xd, get_frame_new_buffer(cm), 0, 0);

  vp9_setup_block_planes(&x->e_mbd, cm->subsampling_x, cm->subsampling_y);

  xd->mi_8x8[0]->mbmi.mode = DC_PRED;
  xd->mi_8x8[0]->mbmi.uv_mode = DC_PRED;

  vp9_zero(cm->counts.y_mode);
  vp9_zero(cm->counts.uv_mode);
  vp9_zero(cm->counts.inter_mode);
  vp9_zero(cm->counts.partition);
  vp9_zero(cm->counts.intra_inter);
  vp9_zero(cm->counts.comp_inter);
  vp9_zero(cm->counts.single_ref);
  vp9_zero(cm->counts.comp_ref);
  vp9_zero(cm->counts.tx);
  vp9_zero(cm->counts.skip);

  // Note: this memset assumes above_context[0], [1] and [2]
  // are allocated as part of the same buffer.
  vpx_memset(cpi->above_context[0], 0,
             sizeof(*cpi->above_context[0]) *
             2 * aligned_mi_cols * MAX_MB_PLANE);
  vpx_memset(cpi->above_seg_context, 0,
             sizeof(*cpi->above_seg_context) * aligned_mi_cols);
}

static void switch_lossless_mode(VP9_COMP *cpi, int lossless) {
  if (lossless) {
    // printf("Switching to lossless\n");
    cpi->mb.fwd_txm4x4 = vp9_fwht4x4;
    cpi->mb.e_mbd.itxm_add = vp9_iwht4x4_add;
    cpi->mb.optimize = 0;
    cpi->common.lf.filter_level = 0;
    cpi->zbin_mode_boost_enabled = 0;
    cpi->common.tx_mode = ONLY_4X4;
  } else {
    // printf("Not lossless\n");
    cpi->mb.fwd_txm4x4 = vp9_fdct4x4;
    cpi->mb.e_mbd.itxm_add = vp9_idct4x4_add;
  }
}

static void switch_tx_mode(VP9_COMP *cpi) {
  if (cpi->sf.tx_size_search_method == USE_LARGESTALL &&
      cpi->common.tx_mode >= ALLOW_32X32)
    cpi->common.tx_mode = ALLOW_32X32;
}


static int check_dual_ref_flags(VP9_COMP *cpi) {
  const int ref_flags = cpi->ref_frame_flags;

  if (vp9_segfeature_active(&cpi->common.seg, 1, SEG_LVL_REF_FRAME)) {
    return 0;
  } else {
    return (!!(ref_flags & VP9_GOLD_FLAG) + !!(ref_flags & VP9_LAST_FLAG)
        + !!(ref_flags & VP9_ALT_FLAG)) >= 2;
  }
}

static int get_skip_flag(MODE_INFO **mi_8x8, int mis, int ymbs, int xmbs) {
  int x, y;

  for (y = 0; y < ymbs; y++) {
    for (x = 0; x < xmbs; x++) {
      if (!mi_8x8[y * mis + x]->mbmi.skip)
        return 0;
    }
  }

  return 1;
}

static void set_txfm_flag(MODE_INFO **mi_8x8, int mis, int ymbs, int xmbs,
                          TX_SIZE tx_size) {
  int x, y;

  for (y = 0; y < ymbs; y++) {
    for (x = 0; x < xmbs; x++)
      mi_8x8[y * mis + x]->mbmi.tx_size = tx_size;
  }
}

static void reset_skip_txfm_size_b(const VP9_COMMON *cm, int mis,
                                   TX_SIZE max_tx_size, int bw, int bh,
                                   int mi_row, int mi_col,
                                   MODE_INFO **mi_8x8) {
  if (mi_row >= cm->mi_rows || mi_col >= cm->mi_cols) {
    return;
  } else {
    MB_MODE_INFO * const mbmi = &mi_8x8[0]->mbmi;
    if (mbmi->tx_size > max_tx_size) {
      const int ymbs = MIN(bh, cm->mi_rows - mi_row);
      const int xmbs = MIN(bw, cm->mi_cols - mi_col);

      assert(vp9_segfeature_active(&cm->seg, mbmi->segment_id, SEG_LVL_SKIP) ||
             get_skip_flag(mi_8x8, mis, ymbs, xmbs));
      set_txfm_flag(mi_8x8, mis, ymbs, xmbs, max_tx_size);
    }
  }
}

static void reset_skip_txfm_size_sb(VP9_COMMON *cm, MODE_INFO **mi_8x8,
                                    TX_SIZE max_tx_size, int mi_row, int mi_col,
                                    BLOCK_SIZE bsize) {
  const int mis = cm->mode_info_stride;
  int bw, bh;
  const int bs = num_8x8_blocks_wide_lookup[bsize], hbs = bs / 2;

  if (mi_row >= cm->mi_rows || mi_col >= cm->mi_cols)
    return;

  bw = num_8x8_blocks_wide_lookup[mi_8x8[0]->mbmi.sb_type];
  bh = num_8x8_blocks_high_lookup[mi_8x8[0]->mbmi.sb_type];

  if (bw == bs && bh == bs) {
    reset_skip_txfm_size_b(cm, mis, max_tx_size, bs, bs, mi_row, mi_col,
                           mi_8x8);
  } else if (bw == bs && bh < bs) {
    reset_skip_txfm_size_b(cm, mis, max_tx_size, bs, hbs, mi_row, mi_col,
                           mi_8x8);
    reset_skip_txfm_size_b(cm, mis, max_tx_size, bs, hbs, mi_row + hbs,
                           mi_col, mi_8x8 + hbs * mis);
  } else if (bw < bs && bh == bs) {
    reset_skip_txfm_size_b(cm, mis, max_tx_size, hbs, bs, mi_row, mi_col,
                           mi_8x8);
    reset_skip_txfm_size_b(cm, mis, max_tx_size, hbs, bs, mi_row,
                           mi_col + hbs, mi_8x8 + hbs);
  } else {
    const BLOCK_SIZE subsize = subsize_lookup[PARTITION_SPLIT][bsize];
    int n;

    assert(bw < bs && bh < bs);

    for (n = 0; n < 4; n++) {
      const int mi_dc = hbs * (n & 1);
      const int mi_dr = hbs * (n >> 1);

      reset_skip_txfm_size_sb(cm, &mi_8x8[mi_dr * mis + mi_dc], max_tx_size,
                              mi_row + mi_dr, mi_col + mi_dc, subsize);
    }
  }
}

static void reset_skip_txfm_size(VP9_COMMON *cm, TX_SIZE txfm_max) {
  int mi_row, mi_col;
  const int mis = cm->mode_info_stride;
  MODE_INFO **mi_8x8, **mi_ptr = cm->mi_grid_visible;

  for (mi_row = 0; mi_row < cm->mi_rows; mi_row += 8, mi_ptr += 8 * mis) {
    mi_8x8 = mi_ptr;
    for (mi_col = 0; mi_col < cm->mi_cols; mi_col += 8, mi_8x8 += 8) {
      reset_skip_txfm_size_sb(cm, mi_8x8, txfm_max, mi_row, mi_col,
                              BLOCK_64X64);
    }
  }
}

static MV_REFERENCE_FRAME get_frame_type(VP9_COMP *cpi) {
  if (frame_is_intra_only(&cpi->common))
    return INTRA_FRAME;
  else if (cpi->rc.is_src_frame_alt_ref && cpi->refresh_golden_frame)
    return ALTREF_FRAME;
  else if (cpi->refresh_golden_frame || cpi->refresh_alt_ref_frame)
    return LAST_FRAME;
  else
    return GOLDEN_FRAME;
}

static void select_tx_mode(VP9_COMP *cpi) {
  if (cpi->oxcf.lossless) {
    cpi->common.tx_mode = ONLY_4X4;
  } else if (cpi->common.current_video_frame == 0) {
    cpi->common.tx_mode = TX_MODE_SELECT;
  } else {
    if (cpi->sf.tx_size_search_method == USE_LARGESTALL) {
      cpi->common.tx_mode = ALLOW_32X32;
    } else if (cpi->sf.tx_size_search_method == USE_FULL_RD) {
      int frame_type = get_frame_type(cpi);
      cpi->common.tx_mode =
          cpi->rd_tx_select_threshes[frame_type][ALLOW_32X32]
          > cpi->rd_tx_select_threshes[frame_type][TX_MODE_SELECT] ?
          ALLOW_32X32 : TX_MODE_SELECT;
    } else {
      unsigned int total = 0;
      int i;
      for (i = 0; i < TX_SIZES; ++i)
        total += cpi->tx_stepdown_count[i];
      if (total) {
        double fraction = (double)cpi->tx_stepdown_count[0] / total;
        cpi->common.tx_mode = fraction > 0.90 ? ALLOW_32X32 : TX_MODE_SELECT;
        // printf("fraction = %f\n", fraction);
      }  // else keep unchanged
    }
  }
}

// Start RTC Exploration
typedef enum {
  BOTH_ZERO = 0,
  ZERO_PLUS_PREDICTED = 1,
  BOTH_PREDICTED = 2,
  NEW_PLUS_NON_INTRA = 3,
  BOTH_NEW = 4,
  INTRA_PLUS_NON_INTRA = 5,
  BOTH_INTRA = 6,
  INVALID_CASE = 9
} motion_vector_context;

static void set_mode_info(MB_MODE_INFO *mbmi, BLOCK_SIZE bsize,
                          MB_PREDICTION_MODE mode) {
  mbmi->interp_filter = EIGHTTAP;
  mbmi->mode = mode;
  mbmi->mv[0].as_int = 0;
  mbmi->mv[1].as_int = 0;
  if (mode < NEARESTMV) {
    mbmi->ref_frame[0] = INTRA_FRAME;
  } else {
    mbmi->ref_frame[0] = LAST_FRAME;
  }

  mbmi->ref_frame[1] = INTRA_FRAME;
  mbmi->tx_size = max_txsize_lookup[bsize];
  mbmi->uv_mode = mode;
  mbmi->skip = 0;
  mbmi->sb_type = bsize;
  mbmi->segment_id = 0;
}

static INLINE int get_block_row(int b32i, int b16i, int b8i) {
  return ((b32i >> 1) << 2) + ((b16i >> 1) << 1) + (b8i >> 1);
}

static INLINE int get_block_col(int b32i, int b16i, int b8i) {
  return ((b32i & 1) << 2) + ((b16i & 1) << 1) + (b8i & 1);
}

static void nonrd_use_partition(VP9_COMP *cpi, const TileInfo *const tile,
                                TOKENEXTRA **tp, int mi_row, int mi_col,
                                BLOCK_SIZE bsize, int *rate, int64_t *dist) {
  VP9_COMMON *const cm = &cpi->common;
  MACROBLOCK *const x = &cpi->mb;
  MACROBLOCKD *const xd = &cpi->mb.e_mbd;
  int mis = cm->mode_info_stride;
  int br, bc;
  int i, j;
  MB_PREDICTION_MODE mode = DC_PRED;
  int rows = MIN(MI_BLOCK_SIZE, tile->mi_row_end - mi_row);
  int cols = MIN(MI_BLOCK_SIZE, tile->mi_col_end - mi_col);

  int bw = num_8x8_blocks_wide_lookup[bsize];
  int bh = num_8x8_blocks_high_lookup[bsize];

  int brate = 0;
  int64_t bdist = 0;
  *rate = 0;
  *dist = 0;

  // find prediction mode for each 8x8 block
  for (br = 0; br < rows; br += bh) {
    for (bc = 0; bc < cols; bc += bw) {
      int row = mi_row + br;
      int col = mi_col + bc;

      BLOCK_SIZE bs = find_partition_size(bsize, rows - br, cols - bc,
                                          &bh, &bw);

      set_offsets(cpi, tile, row, col, bs);

      if (cm->frame_type != KEY_FRAME)
        vp9_pick_inter_mode(cpi, x, tile, row, col,
                            &brate, &bdist, bs);
      else
        set_mode_info(&xd->mi_8x8[0]->mbmi, bs, mode);

      *rate += brate;
      *dist += bdist;

      for (j = 0; j < bh; ++j)
        for (i = 0; i < bw; ++i)
          xd->mi_8x8[j * mis + i] = xd->mi_8x8[0];
    }
  }
}

static void encode_nonrd_sb_row(VP9_COMP *cpi, const TileInfo *const tile,
                                int mi_row, TOKENEXTRA **tp) {
  int mi_col;

  // Initialize the left context for the new SB row
  vpx_memset(&cpi->left_context, 0, sizeof(cpi->left_context));
  vpx_memset(cpi->left_seg_context, 0, sizeof(cpi->left_seg_context));

  // Code each SB in the row
  for (mi_col = tile->mi_col_start; mi_col < tile->mi_col_end;
       mi_col += MI_BLOCK_SIZE) {
    int dummy_rate;
    int64_t dummy_dist;

    cpi->mb.source_variance = UINT_MAX;

    if (cpi->sf.partition_search_type == FIXED_PARTITION) {
      nonrd_use_partition(cpi, tile, tp, mi_row, mi_col,
                          cpi->sf.always_this_block_size,
                          &dummy_rate, &dummy_dist);
      encode_sb_rt(cpi, tile, tp, mi_row, mi_col, 1, BLOCK_64X64);
    } else if (cpi->sf.partition_search_type == VAR_BASED_FIXED_PARTITION ||
               cpi->sf.partition_search_type == VAR_BASED_PARTITION) {
      // TODO(debargha): Implement VAR_BASED_PARTITION as a separate case.
      // Currently both VAR_BASED_FIXED_PARTITION/VAR_BASED_PARTITION
      // map to the same thing.
      BLOCK_SIZE bsize = get_nonrd_var_based_fixed_partition(cpi,
                                                             mi_row,
                                                             mi_col);
      nonrd_use_partition(cpi, tile, tp, mi_row, mi_col,
                          bsize, &dummy_rate, &dummy_dist);
      encode_sb_rt(cpi, tile, tp, mi_row, mi_col, 1, BLOCK_64X64);
    } else {
      assert(0);
    }
  }
}
// end RTC play code

static void encode_frame_internal(VP9_COMP *cpi) {
  int mi_row;
  MACROBLOCK *const x = &cpi->mb;
  VP9_COMMON *const cm = &cpi->common;
  MACROBLOCKD *const xd = &x->e_mbd;

//  fprintf(stderr, "encode_frame_internal frame %d (%d) type %d\n",
//           cpi->common.current_video_frame, cpi->common.show_frame,
//           cm->frame_type);

  vp9_zero(cm->counts.switchable_interp);
  vp9_zero(cpi->tx_stepdown_count);

  xd->mi_8x8 = cm->mi_grid_visible;
  // required for vp9_frame_init_quantizer
  xd->mi_8x8[0] = cm->mi;

  xd->last_mi = cm->prev_mi;

  vp9_zero(cm->counts.mv);
  vp9_zero(cpi->coef_counts);
  vp9_zero(cm->counts.eob_branch);

  cpi->mb.e_mbd.lossless = cm->base_qindex == 0 && cm->y_dc_delta_q == 0
      && cm->uv_dc_delta_q == 0 && cm->uv_ac_delta_q == 0;
  switch_lossless_mode(cpi, cpi->mb.e_mbd.lossless);

  vp9_frame_init_quantizer(cpi);

  vp9_initialize_rd_consts(cpi);
  vp9_initialize_me_consts(cpi, cm->base_qindex);
  switch_tx_mode(cpi);

  if (cpi->oxcf.tuning == VP8_TUNE_SSIM) {
    // Initialize encode frame context.
    init_encode_frame_mb_context(cpi);

    // Build a frame level activity map
    build_activity_map(cpi);
  }

  // Re-initialize encode frame context.
  init_encode_frame_mb_context(cpi);

  vp9_zero(cpi->rd_comp_pred_diff);
  vp9_zero(cpi->rd_filter_diff);
  vp9_zero(cpi->rd_tx_select_diff);
  vp9_zero(cpi->rd_tx_select_threshes);

  set_prev_mi(cm);

  if (cpi->sf.use_nonrd_pick_mode) {
    // Initialize internal buffer pointers for rtc coding, where non-RD
    // mode decision is used and hence no buffer pointer swap needed.
    int i;
    struct macroblock_plane *const p = x->plane;
    struct macroblockd_plane *const pd = xd->plane;
    PICK_MODE_CONTEXT *ctx = &cpi->mb.sb64_context;

    for (i = 0; i < MAX_MB_PLANE; ++i) {
      p[i].coeff = ctx->coeff_pbuf[i][0];
      p[i].qcoeff = ctx->qcoeff_pbuf[i][0];
      pd[i].dqcoeff = ctx->dqcoeff_pbuf[i][0];
      p[i].eobs = ctx->eobs_pbuf[i][0];
    }
  }

  {
    struct vpx_usec_timer emr_timer;
    vpx_usec_timer_start(&emr_timer);

    {
      // Take tiles into account and give start/end MB
      int tile_col, tile_row;
      TOKENEXTRA *tp = cpi->tok;
      const int tile_cols = 1 << cm->log2_tile_cols;
      const int tile_rows = 1 << cm->log2_tile_rows;

      for (tile_row = 0; tile_row < tile_rows; tile_row++) {
        for (tile_col = 0; tile_col < tile_cols; tile_col++) {
          TileInfo tile;
          TOKENEXTRA *tp_old = tp;

          // For each row of SBs in the frame
          vp9_tile_init(&tile, cm, tile_row, tile_col);
          for (mi_row = tile.mi_row_start;
               mi_row < tile.mi_row_end; mi_row += MI_BLOCK_SIZE) {
            if (cpi->sf.use_nonrd_pick_mode)
              encode_nonrd_sb_row(cpi, &tile, mi_row, &tp);
            else
              encode_rd_sb_row(cpi, &tile, mi_row, &tp);
          }
          cpi->tok_count[tile_row][tile_col] = (unsigned int)(tp - tp_old);
          assert(tp - cpi->tok <= get_token_alloc(cm->mb_rows, cm->mb_cols));
        }
      }
    }

    vpx_usec_timer_mark(&emr_timer);
    cpi->time_encode_sb_row += vpx_usec_timer_elapsed(&emr_timer);
  }

  if (cpi->sf.skip_encode_sb) {
    int j;
    unsigned int intra_count = 0, inter_count = 0;
    for (j = 0; j < INTRA_INTER_CONTEXTS; ++j) {
      intra_count += cm->counts.intra_inter[j][0];
      inter_count += cm->counts.intra_inter[j][1];
    }
    cpi->sf.skip_encode_frame = ((intra_count << 2) < inter_count);
    cpi->sf.skip_encode_frame &= (cm->frame_type != KEY_FRAME);
    cpi->sf.skip_encode_frame &= cm->show_frame;
  } else {
    cpi->sf.skip_encode_frame = 0;
  }

#if 0
  // Keep record of the total distortion this time around for future use
  cpi->last_frame_distortion = cpi->frame_distortion;
#endif
}

void vp9_encode_frame(VP9_COMP *cpi) {
  VP9_COMMON *const cm = &cpi->common;

  // In the longer term the encoder should be generalized to match the
  // decoder such that we allow compound where one of the 3 buffers has a
  // different sign bias and that buffer is then the fixed ref. However, this
  // requires further work in the rd loop. For now the only supported encoder
  // side behavior is where the ALT ref buffer has opposite sign bias to
  // the other two.
  if (!frame_is_intra_only(cm)) {
    if ((cm->ref_frame_sign_bias[ALTREF_FRAME] ==
             cm->ref_frame_sign_bias[GOLDEN_FRAME]) ||
        (cm->ref_frame_sign_bias[ALTREF_FRAME] ==
             cm->ref_frame_sign_bias[LAST_FRAME])) {
      cm->allow_comp_inter_inter = 0;
    } else {
      cm->allow_comp_inter_inter = 1;
      cm->comp_fixed_ref = ALTREF_FRAME;
      cm->comp_var_ref[0] = LAST_FRAME;
      cm->comp_var_ref[1] = GOLDEN_FRAME;
    }
  }

  if (cpi->sf.frame_parameter_update) {
    int i;
    REFERENCE_MODE reference_mode;
    /*
     * This code does a single RD pass over the whole frame assuming
     * either compound, single or hybrid prediction as per whatever has
     * worked best for that type of frame in the past.
     * It also predicts whether another coding mode would have worked
     * better that this coding mode. If that is the case, it remembers
     * that for subsequent frames.
     * It does the same analysis for transform size selection also.
     */
    const MV_REFERENCE_FRAME frame_type = get_frame_type(cpi);
    const int64_t *mode_thresh = cpi->rd_prediction_type_threshes[frame_type];
    const int64_t *filter_thresh = cpi->rd_filter_threshes[frame_type];

    /* prediction (compound, single or hybrid) mode selection */
    if (frame_type == 3 || !cm->allow_comp_inter_inter)
      reference_mode = SINGLE_REFERENCE;
    else if (mode_thresh[COMPOUND_REFERENCE] > mode_thresh[SINGLE_REFERENCE] &&
             mode_thresh[COMPOUND_REFERENCE] >
                 mode_thresh[REFERENCE_MODE_SELECT] &&
             check_dual_ref_flags(cpi) &&
             cpi->static_mb_pct == 100)
      reference_mode = COMPOUND_REFERENCE;
    else if (mode_thresh[SINGLE_REFERENCE] > mode_thresh[REFERENCE_MODE_SELECT])
      reference_mode = SINGLE_REFERENCE;
    else
      reference_mode = REFERENCE_MODE_SELECT;

    if (cm->interp_filter == SWITCHABLE) {
      if (frame_type != ALTREF_FRAME &&
          filter_thresh[EIGHTTAP_SMOOTH] > filter_thresh[EIGHTTAP] &&
          filter_thresh[EIGHTTAP_SMOOTH] > filter_thresh[EIGHTTAP_SHARP] &&
          filter_thresh[EIGHTTAP_SMOOTH] > filter_thresh[SWITCHABLE - 1]) {
        cm->interp_filter = EIGHTTAP_SMOOTH;
      } else if (filter_thresh[EIGHTTAP_SHARP] > filter_thresh[EIGHTTAP] &&
          filter_thresh[EIGHTTAP_SHARP] > filter_thresh[SWITCHABLE - 1]) {
        cm->interp_filter = EIGHTTAP_SHARP;
      } else if (filter_thresh[EIGHTTAP] > filter_thresh[SWITCHABLE - 1]) {
        cm->interp_filter = EIGHTTAP;
      }
    }

    cpi->mb.e_mbd.lossless = cpi->oxcf.lossless;

    /* transform size selection (4x4, 8x8, 16x16 or select-per-mb) */
    select_tx_mode(cpi);
    cm->reference_mode = reference_mode;

    encode_frame_internal(cpi);

    for (i = 0; i < REFERENCE_MODES; ++i) {
      const int diff = (int) (cpi->rd_comp_pred_diff[i] / cm->MBs);
      cpi->rd_prediction_type_threshes[frame_type][i] += diff;
      cpi->rd_prediction_type_threshes[frame_type][i] >>= 1;
    }

    for (i = 0; i < SWITCHABLE_FILTER_CONTEXTS; i++) {
      const int64_t diff = cpi->rd_filter_diff[i] / cm->MBs;
      cpi->rd_filter_threshes[frame_type][i] =
          (cpi->rd_filter_threshes[frame_type][i] + diff) / 2;
    }

    for (i = 0; i < TX_MODES; ++i) {
      int64_t pd = cpi->rd_tx_select_diff[i];
      int diff;
      if (i == TX_MODE_SELECT)
        pd -= RDCOST(cpi->mb.rdmult, cpi->mb.rddiv, 2048 * (TX_SIZES - 1), 0);
      diff = (int) (pd / cm->MBs);
      cpi->rd_tx_select_threshes[frame_type][i] += diff;
      cpi->rd_tx_select_threshes[frame_type][i] /= 2;
    }

    if (cm->reference_mode == REFERENCE_MODE_SELECT) {
      int single_count_zero = 0;
      int comp_count_zero = 0;

      for (i = 0; i < COMP_INTER_CONTEXTS; i++) {
        single_count_zero += cm->counts.comp_inter[i][0];
        comp_count_zero += cm->counts.comp_inter[i][1];
      }

      if (comp_count_zero == 0) {
        cm->reference_mode = SINGLE_REFERENCE;
        vp9_zero(cm->counts.comp_inter);
      } else if (single_count_zero == 0) {
        cm->reference_mode = COMPOUND_REFERENCE;
        vp9_zero(cm->counts.comp_inter);
      }
    }

    if (cm->tx_mode == TX_MODE_SELECT) {
      int count4x4 = 0;
      int count8x8_lp = 0, count8x8_8x8p = 0;
      int count16x16_16x16p = 0, count16x16_lp = 0;
      int count32x32 = 0;

      for (i = 0; i < TX_SIZE_CONTEXTS; ++i) {
        count4x4 += cm->counts.tx.p32x32[i][TX_4X4];
        count4x4 += cm->counts.tx.p16x16[i][TX_4X4];
        count4x4 += cm->counts.tx.p8x8[i][TX_4X4];

        count8x8_lp += cm->counts.tx.p32x32[i][TX_8X8];
        count8x8_lp += cm->counts.tx.p16x16[i][TX_8X8];
        count8x8_8x8p += cm->counts.tx.p8x8[i][TX_8X8];

        count16x16_16x16p += cm->counts.tx.p16x16[i][TX_16X16];
        count16x16_lp += cm->counts.tx.p32x32[i][TX_16X16];
        count32x32 += cm->counts.tx.p32x32[i][TX_32X32];
      }

      if (count4x4 == 0 && count16x16_lp == 0 && count16x16_16x16p == 0 &&
          count32x32 == 0) {
        cm->tx_mode = ALLOW_8X8;
        reset_skip_txfm_size(cm, TX_8X8);
      } else if (count8x8_8x8p == 0 && count16x16_16x16p == 0 &&
                 count8x8_lp == 0 && count16x16_lp == 0 && count32x32 == 0) {
        cm->tx_mode = ONLY_4X4;
        reset_skip_txfm_size(cm, TX_4X4);
      } else if (count8x8_lp == 0 && count16x16_lp == 0 && count4x4 == 0) {
        cm->tx_mode = ALLOW_32X32;
      } else if (count32x32 == 0 && count8x8_lp == 0 && count4x4 == 0) {
        cm->tx_mode = ALLOW_16X16;
        reset_skip_txfm_size(cm, TX_16X16);
      }
    }
  } else {
    // Force the usage of the BILINEAR interp_filter.
    cm->interp_filter = BILINEAR;
    encode_frame_internal(cpi);
  }
}

static void sum_intra_stats(FRAME_COUNTS *counts, const MODE_INFO *mi) {
  const MB_PREDICTION_MODE y_mode = mi->mbmi.mode;
  const MB_PREDICTION_MODE uv_mode = mi->mbmi.uv_mode;
  const BLOCK_SIZE bsize = mi->mbmi.sb_type;

  ++counts->uv_mode[y_mode][uv_mode];

  if (bsize < BLOCK_8X8) {
    int idx, idy;
    const int num_4x4_blocks_wide = num_4x4_blocks_wide_lookup[bsize];
    const int num_4x4_blocks_high = num_4x4_blocks_high_lookup[bsize];
    for (idy = 0; idy < 2; idy += num_4x4_blocks_high)
      for (idx = 0; idx < 2; idx += num_4x4_blocks_wide)
        ++counts->y_mode[0][mi->bmi[idy * 2 + idx].as_mode];
  } else {
    ++counts->y_mode[size_group_lookup[bsize]][y_mode];
  }
}

// Experimental stub function to create a per MB zbin adjustment based on
// some previously calculated measure of MB activity.
static void adjust_act_zbin(VP9_COMP *cpi, MACROBLOCK *x) {
#if USE_ACT_INDEX
  x->act_zbin_adj = *(x->mb_activity_ptr);
#else
  int64_t a;
  int64_t b;
  int64_t act = *(x->mb_activity_ptr);

  // Apply the masking to the RD multiplier.
  a = act + 4 * cpi->activity_avg;
  b = 4 * act + cpi->activity_avg;

  if (act > cpi->activity_avg)
    x->act_zbin_adj = (int) (((int64_t) b + (a >> 1)) / a) - 1;
  else
    x->act_zbin_adj = 1 - (int) (((int64_t) a + (b >> 1)) / b);
#endif
}

static int get_zbin_mode_boost(const MB_MODE_INFO *mbmi, int enabled) {
  if (enabled) {
    if (is_inter_block(mbmi)) {
      if (mbmi->mode == ZEROMV) {
        return mbmi->ref_frame[0] != LAST_FRAME ? GF_ZEROMV_ZBIN_BOOST
                                                : LF_ZEROMV_ZBIN_BOOST;
      } else {
        return mbmi->sb_type < BLOCK_8X8 ? SPLIT_MV_ZBIN_BOOST
                                         : MV_ZBIN_BOOST;
      }
    } else {
      return INTRA_ZBIN_BOOST;
    }
  } else {
    return 0;
  }
}

static void encode_superblock(VP9_COMP *cpi, TOKENEXTRA **t, int output_enabled,
                              int mi_row, int mi_col, BLOCK_SIZE bsize) {
  VP9_COMMON *const cm = &cpi->common;
  MACROBLOCK *const x = &cpi->mb;
  MACROBLOCKD *const xd = &x->e_mbd;
  MODE_INFO **mi_8x8 = xd->mi_8x8;
  MODE_INFO *mi = mi_8x8[0];
  MB_MODE_INFO *mbmi = &mi->mbmi;
  PICK_MODE_CONTEXT *ctx = get_block_context(x, bsize);
  unsigned int segment_id = mbmi->segment_id;
  const int mis = cm->mode_info_stride;
  const int mi_width = num_8x8_blocks_wide_lookup[bsize];
  const int mi_height = num_8x8_blocks_high_lookup[bsize];

  x->skip_recode = !x->select_txfm_size && mbmi->sb_type >= BLOCK_8X8 &&
                   (cpi->oxcf.aq_mode != COMPLEXITY_AQ) &&
                   !cpi->sf.use_nonrd_pick_mode;
  x->skip_optimize = ctx->is_coded;
  ctx->is_coded = 1;
  x->use_lp32x32fdct = cpi->sf.use_lp32x32fdct;
  x->skip_encode = (!output_enabled && cpi->sf.skip_encode_frame &&
                    x->q_index < QIDX_SKIP_THRESH);
  if (x->skip_encode)
    return;

  if (cm->frame_type == KEY_FRAME) {
    if (cpi->oxcf.tuning == VP8_TUNE_SSIM) {
      adjust_act_zbin(cpi, x);
      vp9_update_zbin_extra(cpi, x);
    }
  } else {
    set_ref_ptrs(cm, xd, mbmi->ref_frame[0], mbmi->ref_frame[1]);
    xd->interp_kernel = vp9_get_interp_kernel(mbmi->interp_filter);

    if (cpi->oxcf.tuning == VP8_TUNE_SSIM) {
      // Adjust the zbin based on this MB rate.
      adjust_act_zbin(cpi, x);
    }

    // Experimental code. Special case for gf and arf zeromv modes.
    // Increase zbin size to suppress noise
    cpi->zbin_mode_boost = get_zbin_mode_boost(mbmi,
                                               cpi->zbin_mode_boost_enabled);
    vp9_update_zbin_extra(cpi, x);
  }

  if (!is_inter_block(mbmi)) {
    int plane;
    mbmi->skip = 1;
    for (plane = 0; plane < MAX_MB_PLANE; ++plane)
      vp9_encode_intra_block_plane(x, MAX(bsize, BLOCK_8X8), plane);
    if (output_enabled)
      sum_intra_stats(&cm->counts, mi);
    vp9_tokenize_sb(cpi, t, !output_enabled, MAX(bsize, BLOCK_8X8));
  } else {
    int ref;
    const int is_compound = has_second_ref(mbmi);
    for (ref = 0; ref < 1 + is_compound; ++ref) {
      YV12_BUFFER_CONFIG *cfg = get_ref_frame_buffer(cpi,
                                                     mbmi->ref_frame[ref]);
      setup_pre_planes(xd, ref, cfg, mi_row, mi_col, &xd->block_refs[ref]->sf);
    }
    vp9_build_inter_predictors_sb(xd, mi_row, mi_col, MAX(bsize, BLOCK_8X8));

    if (!x->skip) {
      mbmi->skip = 1;
      vp9_encode_sb(x, MAX(bsize, BLOCK_8X8));
      vp9_tokenize_sb(cpi, t, !output_enabled, MAX(bsize, BLOCK_8X8));
    } else {
      mbmi->skip = 1;
      if (output_enabled)
        cm->counts.skip[vp9_get_skip_context(xd)][1]++;
      reset_skip_context(xd, MAX(bsize, BLOCK_8X8));
    }
  }

  if (output_enabled) {
    if (cm->tx_mode == TX_MODE_SELECT &&
        mbmi->sb_type >= BLOCK_8X8  &&
        !(is_inter_block(mbmi) &&
            (mbmi->skip ||
             vp9_segfeature_active(&cm->seg, segment_id, SEG_LVL_SKIP)))) {
      ++get_tx_counts(max_txsize_lookup[bsize], vp9_get_tx_size_context(xd),
                      &cm->counts.tx)[mbmi->tx_size];
    } else {
      int x, y;
      TX_SIZE tx_size;
      // The new intra coding scheme requires no change of transform size
      if (is_inter_block(&mi->mbmi)) {
        tx_size = MIN(tx_mode_to_biggest_tx_size[cm->tx_mode],
                      max_txsize_lookup[bsize]);
      } else {
        tx_size = (bsize >= BLOCK_8X8) ? mbmi->tx_size : TX_4X4;
      }

      for (y = 0; y < mi_height; y++)
        for (x = 0; x < mi_width; x++)
          if (mi_col + x < cm->mi_cols && mi_row + y < cm->mi_rows)
            mi_8x8[mis * y + x]->mbmi.tx_size = tx_size;
    }
  }
}