vp9/common/vp9_mvref_common.c

   1
   2 /*
   3  *  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
   4  *
   5  *  Use of this source code is governed by a BSD-style license
   6  *  that can be found in the LICENSE file in the root of the source
   7  *  tree. An additional intellectual property rights grant can be found
   8  *  in the file PATENTS.  All contributing project authors may
   9  *  be found in the AUTHORS file in the root of the source tree.
  10  */
  11
  12 #include "vp9/common/vp9_mvref_common.h"
  13
  14 // This function searches the neighbourhood of a given MB/SB
  15 // to try and find candidate reference vectors.
  16 static void find_mv_refs_idx(const VP9_COMMON *cm, const MACROBLOCKD *xd,
  17                              const TileInfo *const tile,
  18                              MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
  19                              int_mv *mv_ref_list,
  20                              int block, int mi_row, int mi_col) {
  21   const int *ref_sign_bias = cm->ref_frame_sign_bias;
  22   int i, refmv_count = 0;
  23   const MODE_INFO *prev_mi = !cm->error_resilient_mode && cm->prev_mi
  24         ? cm->prev_mi[mi_row * xd->mi_stride + mi_col].src_mi
  25         : NULL;
  26   const MB_MODE_INFO *const prev_mbmi = prev_mi ? &prev_mi->src_mi->mbmi : NULL;
  27   const POSITION *const mv_ref_search = mv_ref_blocks[mi->mbmi.sb_type];
  28   int different_ref_found = 0;
  29   int context_counter = 0;
  30
  31   // Blank the reference vector list
  32   vpx_memset(mv_ref_list, 0, sizeof(*mv_ref_list) * MAX_MV_REF_CANDIDATES);
  33
  34   // The nearest 2 blocks are treated differently
  35   // if the size < 8x8 we get the mv from the bmi substructure,
  36   // and we also need to keep a mode count.
  37   for (i = 0; i < 2; ++i) {
  38     const POSITION *const mv_ref = &mv_ref_search[i];
  39     if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
  40       const MODE_INFO *const candidate_mi = xd->mi[mv_ref->col + mv_ref->row *
  41                                                    xd->mi_stride].src_mi;
  42       const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
  43       // Keep counts for entropy encoding.
  44       context_counter += mode_2_counter[candidate->mode];
  45       different_ref_found = 1;
  46
  47       if (candidate->ref_frame[0] == ref_frame)
  48         ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 0, mv_ref->col, block),
  49                         refmv_count, mv_ref_list, Done);
  50       else if (candidate->ref_frame[1] == ref_frame)
  51         ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 1, mv_ref->col, block),
  52                         refmv_count, mv_ref_list, Done);
  53     }
  54   }
  55
  56   // Check the rest of the neighbors in much the same way
  57   // as before except we don't need to keep track of sub blocks or
  58   // mode counts.
  59   for (; i < MVREF_NEIGHBOURS; ++i) {
  60     const POSITION *const mv_ref = &mv_ref_search[i];
  61     if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
  62       const MB_MODE_INFO *const candidate = &xd->mi[mv_ref->col + mv_ref->row *
  63                                                     xd->mi_stride].src_mi->mbmi;
  64       different_ref_found = 1;
  65
  66       if (candidate->ref_frame[0] == ref_frame)
  67         ADD_MV_REF_LIST(candidate->mv[0], refmv_count, mv_ref_list, Done);
  68       else if (candidate->ref_frame[1] == ref_frame)
  69         ADD_MV_REF_LIST(candidate->mv[1], refmv_count, mv_ref_list, Done);
  70     }
  71   }
  72
  73   // Check the last frame's mode and mv info.
  74   if (prev_mbmi) {
  75     if (prev_mbmi->ref_frame[0] == ref_frame)
  76       ADD_MV_REF_LIST(prev_mbmi->mv[0], refmv_count, mv_ref_list, Done);
  77     else if (prev_mbmi->ref_frame[1] == ref_frame)
  78       ADD_MV_REF_LIST(prev_mbmi->mv[1], refmv_count, mv_ref_list, Done);
  79   }
  80
  81   // Since we couldn't find 2 mvs from the same reference frame
  82   // go back through the neighbors and find motion vectors from
  83   // different reference frames.
  84   if (different_ref_found) {
  85     for (i = 0; i < MVREF_NEIGHBOURS; ++i) {
  86       const POSITION *mv_ref = &mv_ref_search[i];
  87       if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
  88         const MB_MODE_INFO *const candidate = &xd->mi[mv_ref->col + mv_ref->row
  89                                               * xd->mi_stride].src_mi->mbmi;
  90
  91         // If the candidate is INTRA we don't want to consider its mv.
  92         IF_DIFF_REF_FRAME_ADD_MV(candidate, ref_frame, ref_sign_bias,
  93                                  refmv_count, mv_ref_list, Done);
  94       }
  95     }
  96   }
  97
  98   // Since we still don't have a candidate we'll try the last frame.
  99   if (prev_mbmi)
 100     IF_DIFF_REF_FRAME_ADD_MV(prev_mbmi, ref_frame, ref_sign_bias, refmv_count,
 101                              mv_ref_list, Done);
 102
 103  Done:
 104
 105   mi->mbmi.mode_context[ref_frame] = counter_to_context[context_counter];
 106
 107   // Clamp vectors
 108   for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i)
 109     clamp_mv_ref(&mv_ref_list[i].as_mv, xd);
 110 }
 111
 112 void vp9_find_mv_refs(const VP9_COMMON *cm, const MACROBLOCKD *xd,
 113                       const TileInfo *const tile,
 114                       MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
 115                       int_mv *mv_ref_list,
 116                       int mi_row, int mi_col) {
 117   find_mv_refs_idx(cm, xd, tile, mi, ref_frame, mv_ref_list, -1,
 118                    mi_row, mi_col);
 119 }
 120
 121 static void lower_mv_precision(MV *mv, int allow_hp) {
 122   const int use_hp = allow_hp && vp9_use_mv_hp(mv);
 123   if (!use_hp) {
 124     if (mv->row & 1)
 125       mv->row += (mv->row > 0 ? -1 : 1);
 126     if (mv->col & 1)
 127       mv->col += (mv->col > 0 ? -1 : 1);
 128   }
 129 }
 130
 131 void vp9_find_best_ref_mvs(MACROBLOCKD *xd, int allow_hp,
 132                            int_mv *mvlist, int_mv *nearest, int_mv *near) {
 133   int i;
 134   // Make sure all the candidates are properly clamped etc
 135   for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i) {
 136     lower_mv_precision(&mvlist[i].as_mv, allow_hp);
 137     clamp_mv2(&mvlist[i].as_mv, xd);
 138   }
 139   *nearest = mvlist[0];
 140   *near = mvlist[1];
 141 }
 142
 143 void vp9_append_sub8x8_mvs_for_idx(VP9_COMMON *cm, MACROBLOCKD *xd,
 144                                    const TileInfo *const tile,
 145                                    int block, int ref, int mi_row, int mi_col,
 146                                    int_mv *nearest, int_mv *near) {
 147   int_mv mv_list[MAX_MV_REF_CANDIDATES];
 148   MODE_INFO *const mi = xd->mi[0].src_mi;
 149   b_mode_info *bmi = mi->bmi;
 150   int n;
 151
 152   assert(MAX_MV_REF_CANDIDATES == 2);
 153
 154   find_mv_refs_idx(cm, xd, tile, mi, mi->mbmi.ref_frame[ref], mv_list, block,
 155                    mi_row, mi_col);
 156
 157   near->as_int = 0;
 158   switch (block) {
 159     case 0:
 160       nearest->as_int = mv_list[0].as_int;
 161       near->as_int = mv_list[1].as_int;
 162       break;
 163     case 1:
 164     case 2:
 165       nearest->as_int = bmi[0].as_mv[ref].as_int;
 166       for (n = 0; n < MAX_MV_REF_CANDIDATES; ++n)
 167         if (nearest->as_int != mv_list[n].as_int) {
 168           near->as_int = mv_list[n].as_int;
 169           break;
 170         }
 171       break;
 172     case 3: {
 173       int_mv candidates[2 + MAX_MV_REF_CANDIDATES];
 174       candidates[0] = bmi[1].as_mv[ref];
 175       candidates[1] = bmi[0].as_mv[ref];
 176       candidates[2] = mv_list[0];
 177       candidates[3] = mv_list[1];
 178
 179       nearest->as_int = bmi[2].as_mv[ref].as_int;
 180       for (n = 0; n < 2 + MAX_MV_REF_CANDIDATES; ++n)
 181         if (nearest->as_int != candidates[n].as_int) {
 182           near->as_int = candidates[n].as_int;
 183           break;
 184         }
 185       break;
 186     }
 187     default:
 188       assert("Invalid block index.");
 189   }
 190 }