decodemv.c

/*
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */

#include <assert.h>

#include "av1/common/common.h"
#include "av1/common/entropy.h"
#include "av1/common/entropymode.h"
#include "av1/common/entropymv.h"
#include "av1/common/mvref_common.h"
#include "av1/common/pred_common.h"
#include "av1/common/reconinter.h"
#if CONFIG_EXT_INTRA
#include "av1/common/reconintra.h"
#endif  // CONFIG_EXT_INTRA
#include "av1/common/seg_common.h"
#include "av1/common/warped_motion.h"

#include "av1/decoder/decodeframe.h"
#include "av1/decoder/decodemv.h"

#include "aom_dsp/aom_dsp_common.h"

#define ACCT_STR __func__

#define DEC_MISMATCH_DEBUG 0

static PREDICTION_MODE read_intra_mode(aom_reader *r, aom_cdf_prob *cdf) {
  return (PREDICTION_MODE)aom_read_symbol(r, cdf, INTRA_MODES, ACCT_STR);
}

static int read_delta_qindex(AV1_COMMON *cm, MACROBLOCKD *xd, aom_reader *r,
                             MB_MODE_INFO *const mbmi, int mi_col, int mi_row) {
  FRAME_COUNTS *counts = xd->counts;
  int sign, abs, reduced_delta_qindex = 0;
  BLOCK_SIZE bsize = mbmi->sb_type;
  const int b_col = mi_col & (cm->mib_size - 1);
  const int b_row = mi_row & (cm->mib_size - 1);
  const int read_delta_q_flag = (b_col == 0 && b_row == 0);
  int rem_bits, thr;
  int i, smallval;
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  (void)cm;

  if ((bsize != cm->sb_size || mbmi->skip == 0) && read_delta_q_flag) {
    abs = aom_read_symbol(r, ec_ctx->delta_q_cdf, DELTA_Q_PROBS + 1, ACCT_STR);
    smallval = (abs < DELTA_Q_SMALL);
    if (counts) {
      for (i = 0; i < abs; ++i) counts->delta_q[i][1]++;
      if (smallval) counts->delta_q[abs][0]++;
    }

    if (!smallval) {
      rem_bits = aom_read_literal(r, 3, ACCT_STR) + 1;
      thr = (1 << rem_bits) + 1;
      abs = aom_read_literal(r, rem_bits, ACCT_STR) + thr;
    }

    if (abs) {
      sign = aom_read_bit(r, ACCT_STR);
    } else {
      sign = 1;
    }

    reduced_delta_qindex = sign ? -abs : abs;
  }
  return reduced_delta_qindex;
}
#if CONFIG_EXT_DELTA_Q
static int read_delta_lflevel(AV1_COMMON *cm, MACROBLOCKD *xd, aom_reader *r,
#if CONFIG_LOOPFILTER_LEVEL
                              int lf_id,
#endif
                              MB_MODE_INFO *const mbmi, int mi_col,
                              int mi_row) {
  FRAME_COUNTS *counts = xd->counts;
  int sign, abs, reduced_delta_lflevel = 0;
  BLOCK_SIZE bsize = mbmi->sb_type;
  const int b_col = mi_col & (cm->mib_size - 1);
  const int b_row = mi_row & (cm->mib_size - 1);
  const int read_delta_lf_flag = (b_col == 0 && b_row == 0);
  int rem_bits, thr;
  int i, smallval;
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  (void)cm;

  if ((bsize != cm->sb_size || mbmi->skip == 0) && read_delta_lf_flag) {
#if CONFIG_LOOPFILTER_LEVEL
    if (cm->delta_lf_multi) {
      assert(lf_id >= 0 && lf_id < FRAME_LF_COUNT);
      abs = aom_read_symbol(r, ec_ctx->delta_lf_multi_cdf[lf_id],
                            DELTA_LF_PROBS + 1, ACCT_STR);
    } else {
      abs = aom_read_symbol(r, ec_ctx->delta_lf_cdf, DELTA_LF_PROBS + 1,
                            ACCT_STR);
    }
#else
    abs =
        aom_read_symbol(r, ec_ctx->delta_lf_cdf, DELTA_LF_PROBS + 1, ACCT_STR);
#endif  // CONFIG_LOOPFILTER_LEVEL
    smallval = (abs < DELTA_LF_SMALL);
    if (counts) {
#if CONFIG_LOOPFILTER_LEVEL
      if (cm->delta_lf_multi) {
        for (i = 0; i < abs; ++i) counts->delta_lf_multi[lf_id][i][1]++;
        if (smallval) counts->delta_lf_multi[lf_id][abs][0]++;
      } else {
        for (i = 0; i < abs; ++i) counts->delta_lf[i][1]++;
        if (smallval) counts->delta_lf[abs][0]++;
      }
#else
      for (i = 0; i < abs; ++i) counts->delta_lf[i][1]++;
      if (smallval) counts->delta_lf[abs][0]++;
#endif  // CONFIG_LOOPFILTER_LEVEL
    }
    if (!smallval) {
      rem_bits = aom_read_literal(r, 3, ACCT_STR) + 1;
      thr = (1 << rem_bits) + 1;
      abs = aom_read_literal(r, rem_bits, ACCT_STR) + thr;
    }

    if (abs) {
      sign = aom_read_bit(r, ACCT_STR);
    } else {
      sign = 1;
    }

    reduced_delta_lflevel = sign ? -abs : abs;
  }
  return reduced_delta_lflevel;
}
#endif

static UV_PREDICTION_MODE read_intra_mode_uv(FRAME_CONTEXT *ec_ctx,
                                             aom_reader *r,
                                             PREDICTION_MODE y_mode) {
  const UV_PREDICTION_MODE uv_mode =
#if CONFIG_CFL
      aom_read_symbol(r, ec_ctx->uv_mode_cdf[y_mode], UV_INTRA_MODES, ACCT_STR);
#else
      read_intra_mode(r, ec_ctx->uv_mode_cdf[y_mode]);
#endif  // CONFIG_CFL
  return uv_mode;
}

#if CONFIG_CFL
static int read_cfl_alphas(FRAME_CONTEXT *const ec_ctx, aom_reader *r,
                           int *signs_out) {
  const int joint_sign =
      aom_read_symbol(r, ec_ctx->cfl_sign_cdf, CFL_JOINT_SIGNS, "cfl:signs");
  int idx = 0;
  // Magnitudes are only coded for nonzero values
  if (CFL_SIGN_U(joint_sign) != CFL_SIGN_ZERO) {
    aom_cdf_prob *cdf_u = ec_ctx->cfl_alpha_cdf[CFL_CONTEXT_U(joint_sign)];
    idx = aom_read_symbol(r, cdf_u, CFL_ALPHABET_SIZE, "cfl:alpha_u")
          << CFL_ALPHABET_SIZE_LOG2;
  }
  if (CFL_SIGN_V(joint_sign) != CFL_SIGN_ZERO) {
    aom_cdf_prob *cdf_v = ec_ctx->cfl_alpha_cdf[CFL_CONTEXT_V(joint_sign)];
    idx += aom_read_symbol(r, cdf_v, CFL_ALPHABET_SIZE, "cfl:alpha_v");
  }
  *signs_out = joint_sign;
  return idx;
}
#endif

static INTERINTRA_MODE read_interintra_mode(MACROBLOCKD *xd, aom_reader *r,
                                            int size_group) {
  const INTERINTRA_MODE ii_mode = (INTERINTRA_MODE)aom_read_symbol(
      r, xd->tile_ctx->interintra_mode_cdf[size_group], INTERINTRA_MODES,
      ACCT_STR);
  FRAME_COUNTS *counts = xd->counts;
  if (counts) ++counts->interintra_mode[size_group][ii_mode];
  return ii_mode;
}

static PREDICTION_MODE read_inter_mode(FRAME_CONTEXT *ec_ctx, MACROBLOCKD *xd,
                                       aom_reader *r, int16_t ctx) {
  FRAME_COUNTS *counts = xd->counts;
  int16_t mode_ctx = ctx & NEWMV_CTX_MASK;
  int is_newmv, is_zeromv, is_refmv;
#if CONFIG_NEW_MULTISYMBOL
  is_newmv = aom_read_symbol(r, ec_ctx->newmv_cdf[mode_ctx], 2, ACCT_STR) == 0;
#else
  is_newmv = aom_read(r, ec_ctx->newmv_prob[mode_ctx], ACCT_STR) == 0;
#endif
  if (is_newmv) {
    if (counts) ++counts->newmv_mode[mode_ctx][0];
    return NEWMV;
  }
  if (counts) ++counts->newmv_mode[mode_ctx][1];
  if (ctx & (1 << ALL_ZERO_FLAG_OFFSET)) return GLOBALMV;
  mode_ctx = (ctx >> GLOBALMV_OFFSET) & GLOBALMV_CTX_MASK;
#if CONFIG_NEW_MULTISYMBOL
  is_zeromv =
      aom_read_symbol(r, ec_ctx->zeromv_cdf[mode_ctx], 2, ACCT_STR) == 0;
#else
  is_zeromv = aom_read(r, ec_ctx->zeromv_prob[mode_ctx], ACCT_STR) == 0;
#endif
  if (is_zeromv) {
    if (counts) ++counts->zeromv_mode[mode_ctx][0];
    return GLOBALMV;
  }
  if (counts) ++counts->zeromv_mode[mode_ctx][1];
  mode_ctx = (ctx >> REFMV_OFFSET) & REFMV_CTX_MASK;
  if (ctx & (1 << SKIP_NEARESTMV_OFFSET)) mode_ctx = 6;
  if (ctx & (1 << SKIP_NEARMV_OFFSET)) mode_ctx = 7;
  if (ctx & (1 << SKIP_NEARESTMV_SUB8X8_OFFSET)) mode_ctx = 8;
#if CONFIG_NEW_MULTISYMBOL
  is_refmv = aom_read_symbol(r, ec_ctx->refmv_cdf[mode_ctx], 2, ACCT_STR) == 0;
#else
  is_refmv = aom_read(r, ec_ctx->refmv_prob[mode_ctx], ACCT_STR) == 0;
#endif
  if (is_refmv) {
    if (counts) ++counts->refmv_mode[mode_ctx][0];
    return NEARESTMV;
  } else {
    if (counts) ++counts->refmv_mode[mode_ctx][1];
    return NEARMV;
  }
  // Invalid prediction mode.
  assert(0);
}

static void read_drl_idx(FRAME_CONTEXT *ec_ctx, MACROBLOCKD *xd,
                         MB_MODE_INFO *mbmi, aom_reader *r) {
  uint8_t ref_frame_type = av1_ref_frame_type(mbmi->ref_frame);
  mbmi->ref_mv_idx = 0;
  if (mbmi->mode == NEWMV || mbmi->mode == NEW_NEWMV
#if CONFIG_COMPOUND_SINGLEREF
      || mbmi->mode == SR_NEW_NEWMV
#endif  // CONFIG_COMPOUND_SINGLEREF
      ) {
    int idx;
    for (idx = 0; idx < 2; ++idx) {
      if (xd->ref_mv_count[ref_frame_type] > idx + 1) {
        uint8_t drl_ctx = av1_drl_ctx(xd->ref_mv_stack[ref_frame_type], idx);
#if CONFIG_NEW_MULTISYMBOL
        int drl_idx = aom_read_symbol(r, ec_ctx->drl_cdf[drl_ctx], 2, ACCT_STR);
#else
        int drl_idx = aom_read(r, ec_ctx->drl_prob[drl_ctx], ACCT_STR);
#endif
        mbmi->ref_mv_idx = idx + drl_idx;
        if (xd->counts) ++xd->counts->drl_mode[drl_ctx][drl_idx];
        if (!drl_idx) return;
      }
    }
  }
  if (have_nearmv_in_inter_mode(mbmi->mode)) {
    int idx;
    // Offset the NEARESTMV mode.
    // TODO(jingning): Unify the two syntax decoding loops after the NEARESTMV
    // mode is factored in.
    for (idx = 1; idx < 3; ++idx) {
      if (xd->ref_mv_count[ref_frame_type] > idx + 1) {
        uint8_t drl_ctx = av1_drl_ctx(xd->ref_mv_stack[ref_frame_type], idx);
#if CONFIG_NEW_MULTISYMBOL
        int drl_idx = aom_read_symbol(r, ec_ctx->drl_cdf[drl_ctx], 2, ACCT_STR);
#else
        int drl_idx = aom_read(r, ec_ctx->drl_prob[drl_ctx], ACCT_STR);
#endif
        mbmi->ref_mv_idx = idx + drl_idx - 1;
        if (xd->counts) ++xd->counts->drl_mode[drl_ctx][drl_idx];
        if (!drl_idx) return;
      }
    }
  }
}

static MOTION_MODE read_motion_mode(AV1_COMMON *cm, MACROBLOCKD *xd,
                                    MODE_INFO *mi, aom_reader *r) {
  MB_MODE_INFO *mbmi = &mi->mbmi;
#if CONFIG_NEW_MULTISYMBOL
  (void)cm;
#endif

  const MOTION_MODE last_motion_mode_allowed =
      motion_mode_allowed(0, xd->global_motion, xd, mi);
  int motion_mode;
  FRAME_COUNTS *counts = xd->counts;

  if (last_motion_mode_allowed == SIMPLE_TRANSLATION) return SIMPLE_TRANSLATION;

  if (last_motion_mode_allowed == OBMC_CAUSAL) {
#if CONFIG_NEW_MULTISYMBOL
    motion_mode =
        aom_read_symbol(r, xd->tile_ctx->obmc_cdf[mbmi->sb_type], 2, ACCT_STR);
#else
    motion_mode = aom_read(r, cm->fc->obmc_prob[mbmi->sb_type], ACCT_STR);
#endif
    if (counts) ++counts->obmc[mbmi->sb_type][motion_mode];
    return (MOTION_MODE)(SIMPLE_TRANSLATION + motion_mode);
  } else {
    motion_mode =
        aom_read_symbol(r, xd->tile_ctx->motion_mode_cdf[mbmi->sb_type],
                        MOTION_MODES, ACCT_STR);
    if (counts) ++counts->motion_mode[mbmi->sb_type][motion_mode];
    return (MOTION_MODE)(SIMPLE_TRANSLATION + motion_mode);
  }
}

static PREDICTION_MODE read_inter_compound_mode(AV1_COMMON *cm, MACROBLOCKD *xd,
                                                aom_reader *r, int16_t ctx) {
  (void)cm;
#if CONFIG_EXT_SKIP
  FRAME_CONTEXT *const ec_ctx = xd->tile_ctx;
  const int mode =
      xd->mi[0]->mbmi.skip_mode
          ? (NEAREST_NEARESTMV - NEAREST_NEARESTMV)
          : aom_read_symbol(r, ec_ctx->inter_compound_mode_cdf[ctx],
                            INTER_COMPOUND_MODES, ACCT_STR);
  if (xd->mi[0]->mbmi.skip_mode && r->allow_update_cdf)
    update_cdf(ec_ctx->inter_compound_mode_cdf[ctx], mode,
               INTER_COMPOUND_MODES);
#else
  const int mode =
      aom_read_symbol(r, xd->tile_ctx->inter_compound_mode_cdf[ctx],
                      INTER_COMPOUND_MODES, ACCT_STR);
#endif  // CONFIG_EXT_SKIP

  FRAME_COUNTS *counts = xd->counts;
  if (counts) ++counts->inter_compound_mode[ctx][mode];
  assert(is_inter_compound_mode(NEAREST_NEARESTMV + mode));
  return NEAREST_NEARESTMV + mode;
}

#if CONFIG_COMPOUND_SINGLEREF
static PREDICTION_MODE read_inter_singleref_comp_mode(MACROBLOCKD *xd,
                                                      aom_reader *r,
                                                      int16_t ctx) {
  const int mode =
      aom_read_symbol(r, xd->tile_ctx->inter_singleref_comp_mode_cdf[ctx],
                      INTER_SINGLEREF_COMP_MODES, ACCT_STR);
  FRAME_COUNTS *counts = xd->counts;

  if (counts) ++counts->inter_singleref_comp_mode[ctx][mode];

  assert(is_inter_singleref_comp_mode(SR_NEAREST_NEARMV + mode));
  return SR_NEAREST_NEARMV + mode;
}
#endif  // CONFIG_COMPOUND_SINGLEREF

static int read_segment_id(aom_reader *r, struct segmentation_probs *segp) {
  return aom_read_symbol(r, segp->tree_cdf, MAX_SEGMENTS, ACCT_STR);
}

static void read_tx_size_vartx(AV1_COMMON *cm, MACROBLOCKD *xd,
                               MB_MODE_INFO *mbmi, FRAME_COUNTS *counts,
                               TX_SIZE tx_size, int depth, int blk_row,
                               int blk_col, aom_reader *r) {
#if CONFIG_NEW_MULTISYMBOL
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  (void)cm;
#endif
  int is_split = 0;
  const int tx_row = blk_row >> 1;
  const int tx_col = blk_col >> 1;
  const int max_blocks_high = max_block_high(xd, mbmi->sb_type, 0);
  const int max_blocks_wide = max_block_wide(xd, mbmi->sb_type, 0);
  int ctx = txfm_partition_context(xd->above_txfm_context + blk_col,
                                   xd->left_txfm_context + blk_row,
                                   mbmi->sb_type, tx_size);
  TX_SIZE(*const inter_tx_size)
  [MAX_MIB_SIZE] =
      (TX_SIZE(*)[MAX_MIB_SIZE]) & mbmi->inter_tx_size[tx_row][tx_col];
  if (blk_row >= max_blocks_high || blk_col >= max_blocks_wide) return;
  assert(tx_size > TX_4X4);

  if (depth == MAX_VARTX_DEPTH) {
    int idx, idy;
    inter_tx_size[0][0] = tx_size;
    for (idy = 0; idy < AOMMAX(1, tx_size_high_unit[tx_size] / 2); ++idy)
      for (idx = 0; idx < AOMMAX(1, tx_size_wide_unit[tx_size] / 2); ++idx)
        inter_tx_size[idy][idx] = tx_size;
    mbmi->tx_size = tx_size;
    mbmi->min_tx_size = AOMMIN(mbmi->min_tx_size, get_min_tx_size(tx_size));
    txfm_partition_update(xd->above_txfm_context + blk_col,
                          xd->left_txfm_context + blk_row, tx_size, tx_size);
    return;
  }

#if CONFIG_NEW_MULTISYMBOL
  is_split = aom_read_symbol(r, ec_ctx->txfm_partition_cdf[ctx], 2, ACCT_STR);
#else
  is_split = aom_read(r, cm->fc->txfm_partition_prob[ctx], ACCT_STR);
#endif

  if (is_split) {
    const TX_SIZE sub_txs = sub_tx_size_map[tx_size];
    const int bsl = tx_size_wide_unit[sub_txs];
    int i;

    if (counts) ++counts->txfm_partition[ctx][1];

    if (sub_txs == TX_4X4) {
      int idx, idy;
      inter_tx_size[0][0] = sub_txs;
      for (idy = 0; idy < AOMMAX(1, tx_size_high_unit[tx_size] / 2); ++idy)
        for (idx = 0; idx < AOMMAX(1, tx_size_wide_unit[tx_size] / 2); ++idx)
          inter_tx_size[idy][idx] = inter_tx_size[0][0];
      mbmi->tx_size = sub_txs;
      mbmi->min_tx_size = get_min_tx_size(mbmi->tx_size);
      txfm_partition_update(xd->above_txfm_context + blk_col,
                            xd->left_txfm_context + blk_row, sub_txs, tx_size);
      return;
    }

    assert(bsl > 0);
    for (i = 0; i < 4; ++i) {
      int offsetr = blk_row + (i >> 1) * bsl;
      int offsetc = blk_col + (i & 0x01) * bsl;
      read_tx_size_vartx(cm, xd, mbmi, counts, sub_txs, depth + 1, offsetr,
                         offsetc, r);
    }
  } else {
    int idx, idy;
    inter_tx_size[0][0] = tx_size;
    for (idy = 0; idy < AOMMAX(1, tx_size_high_unit[tx_size] / 2); ++idy)
      for (idx = 0; idx < AOMMAX(1, tx_size_wide_unit[tx_size] / 2); ++idx)
        inter_tx_size[idy][idx] = tx_size;
    mbmi->tx_size = tx_size;
    mbmi->min_tx_size = AOMMIN(mbmi->min_tx_size, get_min_tx_size(tx_size));
    if (counts) ++counts->txfm_partition[ctx][0];
    txfm_partition_update(xd->above_txfm_context + blk_col,
                          xd->left_txfm_context + blk_row, tx_size, tx_size);
  }
}

static TX_SIZE read_selected_tx_size(AV1_COMMON *cm, MACROBLOCKD *xd,
                                     int32_t tx_size_cat, aom_reader *r) {
  const int ctx = get_tx_size_context(xd);
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  (void)cm;

  const int depth = aom_read_symbol(r, ec_ctx->tx_size_cdf[tx_size_cat][ctx],
                                    tx_size_cat + 2, ACCT_STR);
  const TX_SIZE tx_size = depth_to_tx_size(depth);
  assert(!is_rect_tx(tx_size));
  return tx_size;
}

static TX_SIZE read_tx_size(AV1_COMMON *cm, MACROBLOCKD *xd, int is_inter,
                            int allow_select_inter, aom_reader *r) {
  const TX_MODE tx_mode = cm->tx_mode;
  const BLOCK_SIZE bsize = xd->mi[0]->mbmi.sb_type;
  if (xd->lossless[xd->mi[0]->mbmi.segment_id]) return TX_4X4;

  if (block_signals_txsize(bsize)) {
    if ((!is_inter || allow_select_inter) && tx_mode == TX_MODE_SELECT) {
      const int32_t tx_size_cat = is_inter ? inter_tx_size_cat_lookup[bsize]
                                           : intra_tx_size_cat_lookup[bsize];
      const TX_SIZE coded_tx_size =
          read_selected_tx_size(cm, xd, tx_size_cat, r);
      if (coded_tx_size > max_txsize_lookup[bsize]) {
        assert(coded_tx_size == max_txsize_lookup[bsize] + 1);
#if CONFIG_RECT_TX_EXT
        if (is_quarter_tx_allowed(xd, &xd->mi[0]->mbmi, is_inter)) {
          int quarter_tx;

          if (quarter_txsize_lookup[bsize] != max_txsize_lookup[bsize]) {
#if CONFIG_NEW_MULTISYMBOL
            quarter_tx =
                aom_read_symbol(r, cm->fc->quarter_tx_size_cdf, 2, ACCT_STR);
#else
            quarter_tx = aom_read(r, cm->fc->quarter_tx_size_prob, ACCT_STR);
            FRAME_COUNTS *counts = xd->counts;
            if (counts) ++counts->quarter_tx_size[quarter_tx];
#endif
          } else {
            quarter_tx = 1;
          }
          return quarter_tx ? quarter_txsize_lookup[bsize]
                            : max_txsize_rect_lookup[bsize];
        }
#endif  // CONFIG_RECT_TX_EXT

        return max_txsize_rect_lookup[bsize];
      }
      return coded_tx_size;
    } else {
      return tx_size_from_tx_mode(bsize, tx_mode, is_inter);
    }
  } else {
    assert(IMPLIES(tx_mode == ONLY_4X4, bsize == BLOCK_4X4));
    return max_txsize_rect_lookup[bsize];
  }
}

static int dec_get_segment_id(const AV1_COMMON *cm, const uint8_t *segment_ids,
                              int mi_offset, int x_mis, int y_mis) {
  int x, y, segment_id = INT_MAX;

  for (y = 0; y < y_mis; y++)
    for (x = 0; x < x_mis; x++)
      segment_id =
          AOMMIN(segment_id, segment_ids[mi_offset + y * cm->mi_cols + x]);

  assert(segment_id >= 0 && segment_id < MAX_SEGMENTS);
  return segment_id;
}

static void set_segment_id(AV1_COMMON *cm, int mi_offset, int x_mis, int y_mis,
                           int segment_id) {
  int x, y;

  assert(segment_id >= 0 && segment_id < MAX_SEGMENTS);

  for (y = 0; y < y_mis; y++)
    for (x = 0; x < x_mis; x++)
      cm->current_frame_seg_map[mi_offset + y * cm->mi_cols + x] = segment_id;
}

static int read_intra_segment_id(AV1_COMMON *const cm, MACROBLOCKD *const xd,
                                 int mi_offset, int x_mis, int y_mis,
                                 aom_reader *r) {
  struct segmentation *const seg = &cm->seg;
  FRAME_COUNTS *counts = xd->counts;
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  struct segmentation_probs *const segp = &ec_ctx->seg;
  int segment_id;

  if (!seg->enabled) return 0;  // Default for disabled segmentation

  assert(seg->update_map && !seg->temporal_update);

  segment_id = read_segment_id(r, segp);
  if (counts) ++counts->seg.tree_total[segment_id];
  set_segment_id(cm, mi_offset, x_mis, y_mis, segment_id);
  return segment_id;
}

static void copy_segment_id(const AV1_COMMON *cm,
                            const uint8_t *last_segment_ids,
                            uint8_t *current_segment_ids, int mi_offset,
                            int x_mis, int y_mis) {
  int x, y;

  for (y = 0; y < y_mis; y++)
    for (x = 0; x < x_mis; x++)
      current_segment_ids[mi_offset + y * cm->mi_cols + x] =
          last_segment_ids ? last_segment_ids[mi_offset + y * cm->mi_cols + x]
                           : 0;
}

static int read_inter_segment_id(AV1_COMMON *const cm, MACROBLOCKD *const xd,
                                 int mi_row, int mi_col, aom_reader *r) {
  struct segmentation *const seg = &cm->seg;
  FRAME_COUNTS *counts = xd->counts;
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  struct segmentation_probs *const segp = &ec_ctx->seg;

  MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
  int predicted_segment_id, segment_id;
  const int mi_offset = mi_row * cm->mi_cols + mi_col;
  const int bw = mi_size_wide[mbmi->sb_type];
  const int bh = mi_size_high[mbmi->sb_type];

  // TODO(slavarnway): move x_mis, y_mis into xd ?????
  const int x_mis = AOMMIN(cm->mi_cols - mi_col, bw);
  const int y_mis = AOMMIN(cm->mi_rows - mi_row, bh);

  if (!seg->enabled) return 0;  // Default for disabled segmentation

  predicted_segment_id = cm->last_frame_seg_map
                             ? dec_get_segment_id(cm, cm->last_frame_seg_map,
                                                  mi_offset, x_mis, y_mis)
                             : 0;

  if (!seg->update_map) {
    copy_segment_id(cm, cm->last_frame_seg_map, cm->current_frame_seg_map,
                    mi_offset, x_mis, y_mis);
    return predicted_segment_id;
  }

  if (seg->temporal_update) {
    const int ctx = av1_get_pred_context_seg_id(xd);
#if CONFIG_NEW_MULTISYMBOL
    aom_cdf_prob *pred_cdf = segp->pred_cdf[ctx];
    mbmi->seg_id_predicted = aom_read_symbol(r, pred_cdf, 2, ACCT_STR);
#else
    const aom_prob pred_prob = segp->pred_probs[ctx];
    mbmi->seg_id_predicted = aom_read(r, pred_prob, ACCT_STR);
#endif
    if (counts) ++counts->seg.pred[ctx][mbmi->seg_id_predicted];
    if (mbmi->seg_id_predicted) {
      segment_id = predicted_segment_id;
    } else {
      segment_id = read_segment_id(r, segp);
      if (counts) ++counts->seg.tree_mispred[segment_id];
    }
  } else {
    segment_id = read_segment_id(r, segp);
    if (counts) ++counts->seg.tree_total[segment_id];
  }
  set_segment_id(cm, mi_offset, x_mis, y_mis, segment_id);
  return segment_id;
}

#if CONFIG_EXT_SKIP
static int read_skip_mode(AV1_COMMON *cm, const MACROBLOCKD *xd, int segment_id,
                          aom_reader *r) {
  if (!cm->is_skip_mode_allowed) return 0;

  if (segfeature_active(&cm->seg, segment_id, SEG_LVL_SKIP)) {
    // TODO(zoeliu): To revisit the handling of this scenario.
    return 0;
  } else {
    const int ctx = av1_get_skip_mode_context(xd);
#if CONFIG_NEW_MULTISYMBOL
    FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
    const int skip_mode =
        aom_read_symbol(r, ec_ctx->skip_mode_cdfs[ctx], 2, ACCT_STR);
#else
    const int skip_mode = aom_read(r, cm->fc->skip_mode_probs[ctx], ACCT_STR);
#endif  // CONFIG_NEW_MULTISYMBOL
    FRAME_COUNTS *counts = xd->counts;
    if (counts) ++counts->skip_mode[ctx][skip_mode];

    // TODO(zoeliu): To handle:
    //               if (!is_comp_ref_allowed(xd->mi[0]->mbmi.sb_type))
    return skip_mode;
  }
}
#endif  // CONFIG_EXT_SKIP

static int read_skip(AV1_COMMON *cm, const MACROBLOCKD *xd, int segment_id,
                     aom_reader *r) {
  if (segfeature_active(&cm->seg, segment_id, SEG_LVL_SKIP)) {
    return 1;
  } else {
    const int ctx = av1_get_skip_context(xd);
#if CONFIG_NEW_MULTISYMBOL
    FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
    const int skip = aom_read_symbol(r, ec_ctx->skip_cdfs[ctx], 2, ACCT_STR);
#else
    const int skip = aom_read(r, cm->fc->skip_probs[ctx], ACCT_STR);
#endif
    FRAME_COUNTS *counts = xd->counts;
    if (counts) ++counts->skip[ctx][skip];
    return skip;
  }
}

#if CONFIG_PALETTE_DELTA_ENCODING
// Merge the sorted list of cached colors(cached_colors[0...n_cached_colors-1])
// and the sorted list of transmitted colors(colors[n_cached_colors...n-1]) into
// one single sorted list(colors[...]).
static void merge_colors(uint16_t *colors, uint16_t *cached_colors,
                         int n_colors, int n_cached_colors) {
  if (n_cached_colors == 0) return;
  int cache_idx = 0, trans_idx = n_cached_colors;
  for (int i = 0; i < n_colors; ++i) {
    if (cache_idx < n_cached_colors &&
        (trans_idx >= n_colors ||
         cached_colors[cache_idx] <= colors[trans_idx])) {
      colors[i] = cached_colors[cache_idx++];
    } else {
      assert(trans_idx < n_colors);
      colors[i] = colors[trans_idx++];
    }
  }
}

static void read_palette_colors_y(MACROBLOCKD *const xd, int bit_depth,
                                  PALETTE_MODE_INFO *const pmi, aom_reader *r) {
  uint16_t color_cache[2 * PALETTE_MAX_SIZE];
  uint16_t cached_colors[PALETTE_MAX_SIZE];
  const int n_cache = av1_get_palette_cache(xd, 0, color_cache);
  const int n = pmi->palette_size[0];
  int idx = 0;
  for (int i = 0; i < n_cache && idx < n; ++i)
    if (aom_read_bit(r, ACCT_STR)) cached_colors[idx++] = color_cache[i];
  if (idx < n) {
    const int n_cached_colors = idx;
    pmi->palette_colors[idx++] = aom_read_literal(r, bit_depth, ACCT_STR);
    if (idx < n) {
      const int min_bits = bit_depth - 3;
      int bits = min_bits + aom_read_literal(r, 2, ACCT_STR);
      int range = (1 << bit_depth) - pmi->palette_colors[idx - 1] - 1;
      for (; idx < n; ++idx) {
        assert(range >= 0);
        const int delta = aom_read_literal(r, bits, ACCT_STR) + 1;
        pmi->palette_colors[idx] = clamp(pmi->palette_colors[idx - 1] + delta,
                                         0, (1 << bit_depth) - 1);
        range -= (pmi->palette_colors[idx] - pmi->palette_colors[idx - 1]);
        bits = AOMMIN(bits, av1_ceil_log2(range));
      }
    }
    merge_colors(pmi->palette_colors, cached_colors, n, n_cached_colors);
  } else {
    memcpy(pmi->palette_colors, cached_colors, n * sizeof(cached_colors[0]));
  }
}

static void read_palette_colors_uv(MACROBLOCKD *const xd, int bit_depth,
                                   PALETTE_MODE_INFO *const pmi,
                                   aom_reader *r) {
  const int n = pmi->palette_size[1];
  // U channel colors.
  uint16_t color_cache[2 * PALETTE_MAX_SIZE];
  uint16_t cached_colors[PALETTE_MAX_SIZE];
  const int n_cache = av1_get_palette_cache(xd, 1, color_cache);
  int idx = 0;
  for (int i = 0; i < n_cache && idx < n; ++i)
    if (aom_read_bit(r, ACCT_STR)) cached_colors[idx++] = color_cache[i];
  if (idx < n) {
    const int n_cached_colors = idx;
    idx += PALETTE_MAX_SIZE;
    pmi->palette_colors[idx++] = aom_read_literal(r, bit_depth, ACCT_STR);
    if (idx < PALETTE_MAX_SIZE + n) {
      const int min_bits = bit_depth - 3;
      int bits = min_bits + aom_read_literal(r, 2, ACCT_STR);
      int range = (1 << bit_depth) - pmi->palette_colors[idx - 1];
      for (; idx < PALETTE_MAX_SIZE + n; ++idx) {
        assert(range >= 0);
        const int delta = aom_read_literal(r, bits, ACCT_STR);
        pmi->palette_colors[idx] = clamp(pmi->palette_colors[idx - 1] + delta,
                                         0, (1 << bit_depth) - 1);
        range -= (pmi->palette_colors[idx] - pmi->palette_colors[idx - 1]);
        bits = AOMMIN(bits, av1_ceil_log2(range));
      }
    }
    merge_colors(pmi->palette_colors + PALETTE_MAX_SIZE, cached_colors, n,
                 n_cached_colors);
  } else {
    memcpy(pmi->palette_colors + PALETTE_MAX_SIZE, cached_colors,
           n * sizeof(cached_colors[0]));
  }

  // V channel colors.
  if (aom_read_bit(r, ACCT_STR)) {  // Delta encoding.
    const int min_bits_v = bit_depth - 4;
    const int max_val = 1 << bit_depth;
    int bits = min_bits_v + aom_read_literal(r, 2, ACCT_STR);
    pmi->palette_colors[2 * PALETTE_MAX_SIZE] =
        aom_read_literal(r, bit_depth, ACCT_STR);
    for (int i = 1; i < n; ++i) {
      int delta = aom_read_literal(r, bits, ACCT_STR);
      if (delta && aom_read_bit(r, ACCT_STR)) delta = -delta;
      int val = (int)pmi->palette_colors[2 * PALETTE_MAX_SIZE + i - 1] + delta;
      if (val < 0) val += max_val;
      if (val >= max_val) val -= max_val;
      pmi->palette_colors[2 * PALETTE_MAX_SIZE + i] = val;
    }
  } else {
    for (int i = 0; i < n; ++i) {
      pmi->palette_colors[2 * PALETTE_MAX_SIZE + i] =
          aom_read_literal(r, bit_depth, ACCT_STR);
    }
  }
}
#endif  // CONFIG_PALETTE_DELTA_ENCODING

static void read_palette_mode_info(AV1_COMMON *const cm, MACROBLOCKD *const xd,
                                   aom_reader *r) {
  MODE_INFO *const mi = xd->mi[0];
  MB_MODE_INFO *const mbmi = &mi->mbmi;
  const MODE_INFO *const above_mi = xd->above_mi;
  const MODE_INFO *const left_mi = xd->left_mi;
  const BLOCK_SIZE bsize = mbmi->sb_type;
  PALETTE_MODE_INFO *const pmi = &mbmi->palette_mode_info;

  assert(bsize >= BLOCK_8X8 && bsize <= BLOCK_LARGEST);
  const int block_palette_idx = bsize - BLOCK_8X8;
  int modev;

  if (mbmi->mode == DC_PRED) {
    int palette_y_mode_ctx = 0;
    if (above_mi) {
      palette_y_mode_ctx +=
          (above_mi->mbmi.palette_mode_info.palette_size[0] > 0);
    }
    if (left_mi) {
      palette_y_mode_ctx +=
          (left_mi->mbmi.palette_mode_info.palette_size[0] > 0);
    }
#if CONFIG_NEW_MULTISYMBOL
    modev = aom_read_symbol(
        r,
        xd->tile_ctx->palette_y_mode_cdf[block_palette_idx][palette_y_mode_ctx],
        2, ACCT_STR);
#else
    modev = aom_read(
        r,
        av1_default_palette_y_mode_prob[block_palette_idx][palette_y_mode_ctx],
        ACCT_STR);
#endif
    if (modev) {
      pmi->palette_size[0] =
          aom_read_symbol(r,
                          xd->tile_ctx->palette_y_size_cdf[block_palette_idx],
                          PALETTE_SIZES, ACCT_STR) +
          2;
#if CONFIG_PALETTE_DELTA_ENCODING
      read_palette_colors_y(xd, cm->bit_depth, pmi, r);
#else
      for (int i = 0; i < pmi->palette_size[0]; ++i)
        pmi->palette_colors[i] = aom_read_literal(r, cm->bit_depth, ACCT_STR);
#endif  // CONFIG_PALETTE_DELTA_ENCODING
    }
  }
  if (mbmi->uv_mode == UV_DC_PRED) {
    const int palette_uv_mode_ctx = (pmi->palette_size[0] > 0);
#if CONFIG_NEW_MULTISYMBOL
    modev = aom_read_symbol(
        r, xd->tile_ctx->palette_uv_mode_cdf[palette_uv_mode_ctx], 2, ACCT_STR);
#else
    modev = aom_read(r, av1_default_palette_uv_mode_prob[palette_uv_mode_ctx],
                     ACCT_STR);
#endif
    if (modev) {
      pmi->palette_size[1] =
          aom_read_symbol(r,
                          xd->tile_ctx->palette_uv_size_cdf[block_palette_idx],
                          PALETTE_SIZES, ACCT_STR) +
          2;
#if CONFIG_PALETTE_DELTA_ENCODING
      read_palette_colors_uv(xd, cm->bit_depth, pmi, r);
#else
      for (int i = 0; i < pmi->palette_size[1]; ++i) {
        pmi->palette_colors[PALETTE_MAX_SIZE + i] =
            aom_read_literal(r, cm->bit_depth, ACCT_STR);
        pmi->palette_colors[2 * PALETTE_MAX_SIZE + i] =
            aom_read_literal(r, cm->bit_depth, ACCT_STR);
      }
#endif  // CONFIG_PALETTE_DELTA_ENCODING
    }
  }
}

#if CONFIG_FILTER_INTRA