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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 neighborhood of a given MB/SB
15 // to try and find candidate reference vectors.
find_mv_refs_idx(const VP9_COMMON * cm,const MACROBLOCKD * xd,MODE_INFO * mi,MV_REFERENCE_FRAME ref_frame,int_mv * mv_ref_list,int block,int mi_row,int mi_col,uint8_t * mode_context)16 static void find_mv_refs_idx(const VP9_COMMON *cm, const MACROBLOCKD *xd,
17                              MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
18                              int_mv *mv_ref_list, int block, int mi_row,
19                              int mi_col, uint8_t *mode_context) {
20   const int *ref_sign_bias = cm->ref_frame_sign_bias;
21   int i, refmv_count = 0;
22   const POSITION *const mv_ref_search = mv_ref_blocks[mi->sb_type];
23   int different_ref_found = 0;
24   int context_counter = 0;
25   const MV_REF *const prev_frame_mvs =
26       cm->use_prev_frame_mvs
27           ? cm->prev_frame->mvs + mi_row * cm->mi_cols + mi_col
28           : NULL;
29   const TileInfo *const tile = &xd->tile;
30 
31   // Blank the reference vector list
32   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 =
41           xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
42       // Keep counts for entropy encoding.
43       context_counter += mode_2_counter[candidate_mi->mode];
44       different_ref_found = 1;
45 
46       if (candidate_mi->ref_frame[0] == ref_frame)
47         ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 0, mv_ref->col, block),
48                         refmv_count, mv_ref_list, Done);
49       else if (candidate_mi->ref_frame[1] == ref_frame)
50         ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 1, mv_ref->col, block),
51                         refmv_count, mv_ref_list, Done);
52     }
53   }
54 
55   // Check the rest of the neighbors in much the same way
56   // as before except we don't need to keep track of sub blocks or
57   // mode counts.
58   for (; i < MVREF_NEIGHBOURS; ++i) {
59     const POSITION *const mv_ref = &mv_ref_search[i];
60     if (is_inside(tile, mi_col, mi_row, cm->mi_rows, mv_ref)) {
61       const MODE_INFO *const candidate_mi =
62           xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
63       different_ref_found = 1;
64 
65       if (candidate_mi->ref_frame[0] == ref_frame)
66         ADD_MV_REF_LIST(candidate_mi->mv[0], refmv_count, mv_ref_list, Done);
67       else if (candidate_mi->ref_frame[1] == ref_frame)
68         ADD_MV_REF_LIST(candidate_mi->mv[1], refmv_count, mv_ref_list, Done);
69     }
70   }
71 
72   // Check the last frame's mode and mv info.
73   if (cm->use_prev_frame_mvs) {
74     if (prev_frame_mvs->ref_frame[0] == ref_frame) {
75       ADD_MV_REF_LIST(prev_frame_mvs->mv[0], refmv_count, mv_ref_list, Done);
76     } else if (prev_frame_mvs->ref_frame[1] == ref_frame) {
77       ADD_MV_REF_LIST(prev_frame_mvs->mv[1], refmv_count, mv_ref_list, Done);
78     }
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 MODE_INFO *const candidate_mi =
89             xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
90 
91         // If the candidate is INTRA we don't want to consider its mv.
92         IF_DIFF_REF_FRAME_ADD_MV(candidate_mi, 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 (cm->use_prev_frame_mvs) {
100     if (prev_frame_mvs->ref_frame[0] != ref_frame &&
101         prev_frame_mvs->ref_frame[0] > INTRA_FRAME) {
102       int_mv mv = prev_frame_mvs->mv[0];
103       if (ref_sign_bias[prev_frame_mvs->ref_frame[0]] !=
104           ref_sign_bias[ref_frame]) {
105         mv.as_mv.row *= -1;
106         mv.as_mv.col *= -1;
107       }
108       ADD_MV_REF_LIST(mv, refmv_count, mv_ref_list, Done);
109     }
110 
111     if (prev_frame_mvs->ref_frame[1] > INTRA_FRAME &&
112         prev_frame_mvs->ref_frame[1] != ref_frame &&
113         prev_frame_mvs->mv[1].as_int != prev_frame_mvs->mv[0].as_int) {
114       int_mv mv = prev_frame_mvs->mv[1];
115       if (ref_sign_bias[prev_frame_mvs->ref_frame[1]] !=
116           ref_sign_bias[ref_frame]) {
117         mv.as_mv.row *= -1;
118         mv.as_mv.col *= -1;
119       }
120       ADD_MV_REF_LIST(mv, refmv_count, mv_ref_list, Done);
121     }
122   }
123 
124 Done:
125 
126   mode_context[ref_frame] = counter_to_context[context_counter];
127 
128   // Clamp vectors
129   for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i)
130     clamp_mv_ref(&mv_ref_list[i].as_mv, xd);
131 }
132 
vp9_find_mv_refs(const VP9_COMMON * cm,const MACROBLOCKD * xd,MODE_INFO * mi,MV_REFERENCE_FRAME ref_frame,int_mv * mv_ref_list,int mi_row,int mi_col,uint8_t * mode_context)133 void vp9_find_mv_refs(const VP9_COMMON *cm, const MACROBLOCKD *xd,
134                       MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
135                       int_mv *mv_ref_list, int mi_row, int mi_col,
136                       uint8_t *mode_context) {
137   find_mv_refs_idx(cm, xd, mi, ref_frame, mv_ref_list, -1, mi_row, mi_col,
138                    mode_context);
139 }
140 
vp9_find_best_ref_mvs(MACROBLOCKD * xd,int allow_hp,int_mv * mvlist,int_mv * nearest_mv,int_mv * near_mv)141 void vp9_find_best_ref_mvs(MACROBLOCKD *xd, int allow_hp, int_mv *mvlist,
142                            int_mv *nearest_mv, int_mv *near_mv) {
143   int i;
144   // Make sure all the candidates are properly clamped etc
145   for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i) {
146     lower_mv_precision(&mvlist[i].as_mv, allow_hp);
147     clamp_mv2(&mvlist[i].as_mv, xd);
148   }
149   *nearest_mv = mvlist[0];
150   *near_mv = mvlist[1];
151 }
152 
vp9_append_sub8x8_mvs_for_idx(VP9_COMMON * cm,MACROBLOCKD * xd,int block,int ref,int mi_row,int mi_col,int_mv * nearest_mv,int_mv * near_mv,uint8_t * mode_context)153 void vp9_append_sub8x8_mvs_for_idx(VP9_COMMON *cm, MACROBLOCKD *xd, int block,
154                                    int ref, int mi_row, int mi_col,
155                                    int_mv *nearest_mv, int_mv *near_mv,
156                                    uint8_t *mode_context) {
157   int_mv mv_list[MAX_MV_REF_CANDIDATES];
158   MODE_INFO *const mi = xd->mi[0];
159   b_mode_info *bmi = mi->bmi;
160   int n;
161 
162   assert(MAX_MV_REF_CANDIDATES == 2);
163 
164   find_mv_refs_idx(cm, xd, mi, mi->ref_frame[ref], mv_list, block, mi_row,
165                    mi_col, mode_context);
166 
167   near_mv->as_int = 0;
168   switch (block) {
169     case 0:
170       nearest_mv->as_int = mv_list[0].as_int;
171       near_mv->as_int = mv_list[1].as_int;
172       break;
173     case 1:
174     case 2:
175       nearest_mv->as_int = bmi[0].as_mv[ref].as_int;
176       for (n = 0; n < MAX_MV_REF_CANDIDATES; ++n)
177         if (nearest_mv->as_int != mv_list[n].as_int) {
178           near_mv->as_int = mv_list[n].as_int;
179           break;
180         }
181       break;
182     case 3: {
183       int_mv candidates[2 + MAX_MV_REF_CANDIDATES];
184       candidates[0] = bmi[1].as_mv[ref];
185       candidates[1] = bmi[0].as_mv[ref];
186       candidates[2] = mv_list[0];
187       candidates[3] = mv_list[1];
188 
189       nearest_mv->as_int = bmi[2].as_mv[ref].as_int;
190       for (n = 0; n < 2 + MAX_MV_REF_CANDIDATES; ++n)
191         if (nearest_mv->as_int != candidates[n].as_int) {
192           near_mv->as_int = candidates[n].as_int;
193           break;
194         }
195       break;
196     }
197     default: assert(0 && "Invalid block index.");
198   }
199 }
200