vp8/decoder/decodemv.c

/*
 *  Copyright (c) 2010 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 "decodemv.h"
#include "treereader.h"
#include "vp8/common/entropymv.h"
#include "vp8/common/entropymode.h"
#include "onyxd_int.h"
#include "vp8/common/findnearmv.h"

static B_PREDICTION_MODE read_bmode(vp8_reader *bc, const vp8_prob *p) {
  const int i = vp8_treed_read(bc, vp8_bmode_tree, p);

  return (B_PREDICTION_MODE)i;
}

static MB_PREDICTION_MODE read_ymode(vp8_reader *bc, const vp8_prob *p) {
  const int i = vp8_treed_read(bc, vp8_ymode_tree, p);

  return (MB_PREDICTION_MODE)i;
}

static MB_PREDICTION_MODE read_kf_ymode(vp8_reader *bc, const vp8_prob *p) {
  const int i = vp8_treed_read(bc, vp8_kf_ymode_tree, p);

  return (MB_PREDICTION_MODE)i;
}

static MB_PREDICTION_MODE read_uv_mode(vp8_reader *bc, const vp8_prob *p) {
  const int i = vp8_treed_read(bc, vp8_uv_mode_tree, p);

  return (MB_PREDICTION_MODE)i;
}

static void read_kf_modes(VP8D_COMP *pbi, MODE_INFO *mi) {
  vp8_reader *const bc = &pbi->mbc[8];
  const int mis = pbi->common.mode_info_stride;

  mi->mbmi.ref_frame = INTRA_FRAME;
  mi->mbmi.mode = read_kf_ymode(bc, vp8_kf_ymode_prob);

  if (mi->mbmi.mode == B_PRED) {
    int i = 0;
    mi->mbmi.is_4x4 = 1;

    do {
      const B_PREDICTION_MODE A = above_block_mode(mi, i, mis);
      const B_PREDICTION_MODE L = left_block_mode(mi, i);

      mi->bmi[i].as_mode = read_bmode(bc, vp8_kf_bmode_prob[A][L]);
    } while (++i < 16);
  }

  mi->mbmi.uv_mode = read_uv_mode(bc, vp8_kf_uv_mode_prob);
}

static int read_mvcomponent(vp8_reader *r, const MV_CONTEXT *mvc) {
  const vp8_prob *const p = (const vp8_prob *)mvc;
  int x = 0;

  if (vp8_read(r, p[mvpis_short])) { /* Large */
    int i = 0;

    do {
      x += vp8_read(r, p[MVPbits + i]) << i;
    } while (++i < 3);

    i = mvlong_width - 1; /* Skip bit 3, which is sometimes implicit */

    do {
      x += vp8_read(r, p[MVPbits + i]) << i;
    } while (--i > 3);

    if (!(x & 0xFFF0) || vp8_read(r, p[MVPbits + 3])) x += 8;
  } else { /* small */
    x = vp8_treed_read(r, vp8_small_mvtree, p + MVPshort);
  }

  if (x && vp8_read(r, p[MVPsign])) x = -x;

  return x;
}

static void read_mv(vp8_reader *r, MV *mv, const MV_CONTEXT *mvc) {
  mv->row = (short)(read_mvcomponent(r, mvc) * 2);
  mv->col = (short)(read_mvcomponent(r, ++mvc) * 2);
}

static void read_mvcontexts(vp8_reader *bc, MV_CONTEXT *mvc) {
  int i = 0;

  do {
    const vp8_prob *up = vp8_mv_update_probs[i].prob;
    vp8_prob *p = (vp8_prob *)(mvc + i);
    vp8_prob *const pstop = p + MVPcount;

    do {
      if (vp8_read(bc, *up++)) {
        const vp8_prob x = (vp8_prob)vp8_read_literal(bc, 7);

        *p = x ? x << 1 : 1;
      }
    } while (++p < pstop);
  } while (++i < 2);
}

static const unsigned char mbsplit_fill_count[4] = { 8, 8, 4, 1 };
static const unsigned char mbsplit_fill_offset[4][16] = {
  { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
  { 0, 1, 4, 5, 8, 9, 12, 13, 2, 3, 6, 7, 10, 11, 14, 15 },
  { 0, 1, 4, 5, 2, 3, 6, 7, 8, 9, 12, 13, 10, 11, 14, 15 },
  { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }
};

static void mb_mode_mv_init(VP8D_COMP *pbi) {
  vp8_reader *const bc = &pbi->mbc[8];
  MV_CONTEXT *const mvc = pbi->common.fc.mvc;

#if CONFIG_ERROR_CONCEALMENT
  /* Default is that no macroblock is corrupt, therefore we initialize
   * mvs_corrupt_from_mb to something very big, which we can be sure is
   * outside the frame. */
  pbi->mvs_corrupt_from_mb = UINT_MAX;
#endif
  /* Read the mb_no_coeff_skip flag */
  pbi->common.mb_no_coeff_skip = (int)vp8_read_bit(bc);

  pbi->prob_skip_false = 0;
  if (pbi->common.mb_no_coeff_skip) {
    pbi->prob_skip_false = (vp8_prob)vp8_read_literal(bc, 8);
  }

  if (pbi->common.frame_type != KEY_FRAME) {
    pbi->prob_intra = (vp8_prob)vp8_read_literal(bc, 8);
    pbi->prob_last = (vp8_prob)vp8_read_literal(bc, 8);
    pbi->prob_gf = (vp8_prob)vp8_read_literal(bc, 8);

    if (vp8_read_bit(bc)) {
      int i = 0;

      do {
        pbi->common.fc.ymode_prob[i] = (vp8_prob)vp8_read_literal(bc, 8);
      } while (++i < 4);
    }

    if (vp8_read_bit(bc)) {
      int i = 0;

      do {
        pbi->common.fc.uv_mode_prob[i] = (vp8_prob)vp8_read_literal(bc, 8);
      } while (++i < 3);
    }

    read_mvcontexts(bc, mvc);
  }
}

const vp8_prob vp8_sub_mv_ref_prob3[8][VP8_SUBMVREFS - 1] = {
  { 147, 136, 18 }, /* SUBMVREF_NORMAL          */
  { 223, 1, 34 },   /* SUBMVREF_LEFT_ABOVE_SAME */
  { 106, 145, 1 },  /* SUBMVREF_LEFT_ZED        */
  { 208, 1, 1 },    /* SUBMVREF_LEFT_ABOVE_ZED  */
  { 179, 121, 1 },  /* SUBMVREF_ABOVE_ZED       */
  { 223, 1, 34 },   /* SUBMVREF_LEFT_ABOVE_SAME */
  { 179, 121, 1 },  /* SUBMVREF_ABOVE_ZED       */
  { 208, 1, 1 }     /* SUBMVREF_LEFT_ABOVE_ZED  */
};

static const vp8_prob *get_sub_mv_ref_prob(const int left, const int above) {
  int lez = (left == 0);
  int aez = (above == 0);
  int lea = (left == above);
  const vp8_prob *prob;

  prob = vp8_sub_mv_ref_prob3[(aez << 2) | (lez << 1) | (lea)];

  return prob;
}

static void decode_split_mv(vp8_reader *const bc, MODE_INFO *mi,
                            const MODE_INFO *left_mb, const MODE_INFO *above_mb,
                            MB_MODE_INFO *mbmi, int_mv best_mv,
                            MV_CONTEXT *const mvc, int mb_to_left_edge,
                            int mb_to_right_edge, int mb_to_top_edge,
                            int mb_to_bottom_edge) {
  int s; /* split configuration (16x8, 8x16, 8x8, 4x4) */
  /* number of partitions in the split configuration (see vp8_mbsplit_count) */
  int num_p;
  int j = 0;

  s = 3;
  num_p = 16;
  if (vp8_read(bc, 110)) {
    s = 2;
    num_p = 4;
    if (vp8_read(bc, 111)) {
      s = vp8_read(bc, 150);
      num_p = 2;
    }
  }

  do /* for each subset j */
  {
    int_mv leftmv, abovemv;
    int_mv blockmv;
    int k; /* first block in subset j */

    const vp8_prob *prob;
    k = vp8_mbsplit_offset[s][j];

    if (!(k & 3)) {
      /* On L edge, get from MB to left of us */
      if (left_mb->mbmi.mode != SPLITMV) {
        leftmv.as_int = left_mb->mbmi.mv.as_int;
      } else {
        leftmv.as_int = (left_mb->bmi + k + 4 - 1)->mv.as_int;
      }
    } else {
      leftmv.as_int = (mi->bmi + k - 1)->mv.as_int;
    }

    if (!(k >> 2)) {
      /* On top edge, get from MB above us */
      if (above_mb->mbmi.mode != SPLITMV) {
        abovemv.as_int = above_mb->mbmi.mv.as_int;
      } else {
        abovemv.as_int = (above_mb->bmi + k + 16 - 4)->mv.as_int;
      }
    } else {
      abovemv.as_int = (mi->bmi + k - 4)->mv.as_int;
    }

    prob = get_sub_mv_ref_prob(leftmv.as_int, abovemv.as_int);

    if (vp8_read(bc, prob[0])) {
      if (vp8_read(bc, prob[1])) {
        blockmv.as_int = 0;
        if (vp8_read(bc, prob[2])) {
          blockmv.as_mv.row = read_mvcomponent(bc, &mvc[0]) * 2;
          blockmv.as_mv.row += best_mv.as_mv.row;
          blockmv.as_mv.col = read_mvcomponent(bc, &mvc[1]) * 2;
          blockmv.as_mv.col += best_mv.as_mv.col;
        }
      } else {
        blockmv.as_int = abovemv.as_int;
      }
    } else {
      blockmv.as_int = leftmv.as_int;
    }

    mbmi->need_to_clamp_mvs |=
        vp8_check_mv_bounds(&blockmv, mb_to_left_edge, mb_to_right_edge,
                            mb_to_top_edge, mb_to_bottom_edge);

    {
      /* Fill (uniform) modes, mvs of jth subset.
       Must do it here because ensuing subsets can
       refer back to us via "left" or "above". */
      const unsigned char *fill_offset;
      unsigned int fill_count = mbsplit_fill_count[s];

      fill_offset =
          &mbsplit_fill_offset[s][(unsigned char)j * mbsplit_fill_count[s]];

      do {
        mi->bmi[*fill_offset].mv.as_int = blockmv.as_int;
        fill_offset++;
      } while (--fill_count);
    }

  } while (++j < num_p);

  mbmi->partitioning = s;
}

static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi,
                             MB_MODE_INFO *mbmi) {
  vp8_reader *const bc = &pbi->mbc[8];
  mbmi->ref_frame = (MV_REFERENCE_FRAME)vp8_read(bc, pbi->prob_intra);
  if (mbmi->ref_frame) { /* inter MB */
    enum { CNT_INTRA, CNT_NEAREST, CNT_NEAR, CNT_SPLITMV };
    int cnt[4];
    int *cntx = cnt;
    int_mv near_mvs[4];
    int_mv *nmv = near_mvs;
    const int mis = pbi->mb.mode_info_stride;
    const MODE_INFO *above = mi - mis;
    const MODE_INFO *left = mi - 1;
    const MODE_INFO *aboveleft = above - 1;
    int *ref_frame_sign_bias = pbi->common.ref_frame_sign_bias;

    mbmi->need_to_clamp_mvs = 0;

    if (vp8_read(bc, pbi->prob_last)) {
      mbmi->ref_frame =
          (MV_REFERENCE_FRAME)((int)(2 + vp8_read(bc, pbi->prob_gf)));
    }

    /* Zero accumulators */
    nmv[0].as_int = nmv[1].as_int = nmv[2].as_int = 0;
    cnt[0] = cnt[1] = cnt[2] = cnt[3] = 0;

    /* Process above */
    if (above->mbmi.ref_frame != INTRA_FRAME) {
      if (above->mbmi.mv.as_int) {
        (++nmv)->as_int = above->mbmi.mv.as_int;
        mv_bias(ref_frame_sign_bias[above->mbmi.ref_frame], mbmi->ref_frame,
                nmv, ref_frame_sign_bias);
        ++cntx;
      }

      *cntx += 2;
    }

    /* Process left */
    if (left->mbmi.ref_frame != INTRA_FRAME) {
      if (left->mbmi.mv.as_int) {
        int_mv this_mv;

        this_mv.as_int = left->mbmi.mv.as_int;
        mv_bias(ref_frame_sign_bias[left->mbmi.ref_frame], mbmi->ref_frame,
                &this_mv, ref_frame_sign_bias);

        if (this_mv.as_int != nmv->as_int) {
          (++nmv)->as_int = this_mv.as_int;
          ++cntx;
        }

        *cntx += 2;
      } else {
        cnt[CNT_INTRA] += 2;
      }
    }

    /* Process above left */
    if (aboveleft->mbmi.ref_frame != INTRA_FRAME) {
      if (aboveleft->mbmi.mv.as_int) {
        int_mv this_mv;

        this_mv.as_int = aboveleft->mbmi.mv.as_int;
        mv_bias(ref_frame_sign_bias[aboveleft->mbmi.ref_frame], mbmi->ref_frame,
                &this_mv, ref_frame_sign_bias);

        if (this_mv.as_int != nmv->as_int) {
          (++nmv)->as_int = this_mv.as_int;
          ++cntx;
        }

        *cntx += 1;
      } else {
        cnt[CNT_INTRA] += 1;
      }
    }

    if (vp8_read(bc, vp8_mode_contexts[cnt[CNT_INTRA]][0])) {
      /* If we have three distinct MV's ... */
      /* See if above-left MV can be merged with NEAREST */
      cnt[CNT_NEAREST] += ((cnt[CNT_SPLITMV] > 0) &
                           (nmv->as_int == near_mvs[CNT_NEAREST].as_int));

      /* Swap near and nearest if necessary */
      if (cnt[CNT_NEAR] > cnt[CNT_NEAREST]) {
        int tmp;
        tmp = cnt[CNT_NEAREST];
        cnt[CNT_NEAREST] = cnt[CNT_NEAR];
        cnt[CNT_NEAR] = tmp;
        tmp = near_mvs[CNT_NEAREST].as_int;
        near_mvs[CNT_NEAREST].as_int = near_mvs[CNT_NEAR].as_int;
        near_mvs[CNT_NEAR].as_int = tmp;
      }

      if (vp8_read(bc, vp8_mode_contexts[cnt[CNT_NEAREST]][1])) {
        if (vp8_read(bc, vp8_mode_contexts[cnt[CNT_NEAR]][2])) {
          int mb_to_top_edge;
          int mb_to_bottom_edge;
          int mb_to_left_edge;
          int mb_to_right_edge;
          MV_CONTEXT *const mvc = pbi->common.fc.mvc;
          int near_index;

          mb_to_top_edge = pbi->mb.mb_to_top_edge;
          mb_to_bottom_edge = pbi->mb.mb_to_bottom_edge;
          mb_to_top_edge -= LEFT_TOP_MARGIN;
          mb_to_bottom_edge += RIGHT_BOTTOM_MARGIN;
          mb_to_right_edge = pbi->mb.mb_to_right_edge;
          mb_to_right_edge += RIGHT_BOTTOM_MARGIN;
          mb_to_left_edge = pbi->mb.mb_to_left_edge;
          mb_to_left_edge -= LEFT_TOP_MARGIN;

          /* Use near_mvs[0] to store the "best" MV */
          near_index = CNT_INTRA + (cnt[CNT_NEAREST] >= cnt[CNT_INTRA]);

          vp8_clamp_mv2(&near_mvs[near_index], &pbi->mb);

          cnt[CNT_SPLITMV] =
              ((above->mbmi.mode == SPLITMV) + (left->mbmi.mode == SPLITMV)) *
                  2 +
              (aboveleft->mbmi.mode == SPLITMV);

          if (vp8_read(bc, vp8_mode_contexts[cnt[CNT_SPLITMV]][3])) {
            decode_split_mv(bc, mi, left, above, mbmi, near_mvs[near_index],
                            mvc, mb_to_left_edge, mb_to_right_edge,
                            mb_to_top_edge, mb_to_bottom_edge);
            mbmi->mv.as_int = mi->bmi[15].mv.as_int;
            mbmi->mode = SPLITMV;
            mbmi->is_4x4 = 1;
          } else {
            int_mv *const mbmi_mv = &mbmi->mv;
            read_mv(bc, &mbmi_mv->as_mv, (const MV_CONTEXT *)mvc);
            mbmi_mv->as_mv.row += near_mvs[near_index].as_mv.row;
            mbmi_mv->as_mv.col += near_mvs[near_index].as_mv.col;

            /* Don't need to check this on NEARMV and NEARESTMV
             * modes since those modes clamp the MV. The NEWMV mode
             * does not, so signal to the prediction stage whether
             * special handling may be required.
             */
            mbmi->need_to_clamp_mvs =
                vp8_check_mv_bounds(mbmi_mv, mb_to_left_edge, mb_to_right_edge,
                                    mb_to_top_edge, mb_to_bottom_edge);
            mbmi->mode = NEWMV;
          }
        } else {
          mbmi->mode = NEARMV;
          mbmi->mv.as_int = near_mvs[CNT_NEAR].as_int;
          vp8_clamp_mv2(&mbmi->mv, &pbi->mb);
        }
      } else {
        mbmi->mode = NEARESTMV;
        mbmi->mv.as_int = near_mvs[CNT_NEAREST].as_int;
        vp8_clamp_mv2(&mbmi->mv, &pbi->mb);
      }
    } else {
      mbmi->mode = ZEROMV;
      mbmi->mv.as_int = 0;
    }

#if CONFIG_ERROR_CONCEALMENT
    if (pbi->ec_enabled && (mbmi->mode != SPLITMV)) {
      mi->bmi[0].mv.as_int = mi->bmi[1].mv.as_int = mi->bmi[2].mv.as_int =
          mi->bmi[3].mv.as_int = mi->bmi[4].mv.as_int = mi->bmi[5].mv.as_int =
              mi->bmi[6].mv.as_int = mi->bmi[7].mv.as_int =
                  mi->bmi[8].mv.as_int = mi->bmi[9].mv.as_int =
                      mi->bmi[10].mv.as_int = mi->bmi[11].mv.as_int =
                          mi->bmi[12].mv.as_int = mi->bmi[13].mv.as_int =
                              mi->bmi[14].mv.as_int = mi->bmi[15].mv.as_int =
                                  mbmi->mv.as_int;
    }
#endif
  } else {
    /* required for left and above block mv */
    mbmi->mv.as_int = 0;

    /* MB is intra coded */
    if ((mbmi->mode = read_ymode(bc, pbi->common.fc.ymode_prob)) == B_PRED) {
      int j = 0;
      mbmi->is_4x4 = 1;
      do {
        mi->bmi[j].as_mode = read_bmode(bc, pbi->common.fc.bmode_prob);
      } while (++j < 16);
    }

    mbmi->uv_mode = read_uv_mode(bc, pbi->common.fc.uv_mode_prob);
  }
}

static void read_mb_features(vp8_reader *r, MB_MODE_INFO *mi, MACROBLOCKD *x) {
  /* Is segmentation enabled */
  if (x->segmentation_enabled && x->update_mb_segmentation_map) {
    /* If so then read the segment id. */
    if (vp8_read(r, x->mb_segment_tree_probs[0])) {
      mi->segment_id =
          (unsigned char)(2 + vp8_read(r, x->mb_segment_tree_probs[2]));
    } else {
      mi->segment_id =
          (unsigned char)(vp8_read(r, x->mb_segment_tree_probs[1]));
    }
  }
}

static void decode_mb_mode_mvs(VP8D_COMP *pbi, MODE_INFO *mi) {
  /* Read the Macroblock segmentation map if it is being updated explicitly
   * this frame (reset to 0 above by default)
   * By default on a key frame reset all MBs to segment 0
   */
  if (pbi->mb.update_mb_segmentation_map) {
    read_mb_features(&pbi->mbc[8], &mi->mbmi, &pbi->mb);
  } else if (pbi->common.frame_type == KEY_FRAME) {
    mi->mbmi.segment_id = 0;
  }

  /* Read the macroblock coeff skip flag if this feature is in use,
   * else default to 0 */
  if (pbi->common.mb_no_coeff_skip) {
    mi->mbmi.mb_skip_coeff = vp8_read(&pbi->mbc[8], pbi->prob_skip_false);
  } else {
    mi->mbmi.mb_skip_coeff = 0;
  }

  mi->mbmi.is_4x4 = 0;
  if (pbi->common.frame_type == KEY_FRAME) {
    read_kf_modes(pbi, mi);
  } else {
    read_mb_modes_mv(pbi, mi, &mi->mbmi);
  }
}

void vp8_decode_mode_mvs(VP8D_COMP *pbi) {
  MODE_INFO *mi = pbi->common.mi;
  int mb_row = -1;
  int mb_to_right_edge_start;

  mb_mode_mv_init(pbi);

  pbi->mb.mb_to_top_edge = 0;
  pbi->mb.mb_to_bottom_edge = ((pbi->common.mb_rows - 1) * 16) << 3;
  mb_to_right_edge_start = ((pbi->common.mb_cols - 1) * 16) << 3;

  while (++mb_row < pbi->common.mb_rows) {
    int mb_col = -1;

    pbi->mb.mb_to_left_edge = 0;
    pbi->mb.mb_to_right_edge = mb_to_right_edge_start;

    while (++mb_col < pbi->common.mb_cols) {
#if CONFIG_ERROR_CONCEALMENT
      int mb_num = mb_row * pbi->common.mb_cols + mb_col;
#endif

      decode_mb_mode_mvs(pbi, mi);

#if CONFIG_ERROR_CONCEALMENT
      /* look for corruption. set mvs_corrupt_from_mb to the current
       * mb_num if the frame is corrupt from this macroblock. */
      if (vp8dx_bool_error(&pbi->mbc[8]) &&
          mb_num < (int)pbi->mvs_corrupt_from_mb) {
        pbi->mvs_corrupt_from_mb = mb_num;
        /* no need to continue since the partition is corrupt from
         * here on.
         */
        return;
      }
#endif

      pbi->mb.mb_to_left_edge -= (16 << 3);
      pbi->mb.mb_to_right_edge -= (16 << 3);
      mi++; /* next macroblock */
    }
    pbi->mb.mb_to_top_edge -= (16 << 3);
    pbi->mb.mb_to_bottom_edge -= (16 << 3);

    mi++; /* skip left predictor each row */
  }
}