pred_common.c 57.9 KB
Newer Older
Jingning Han's avatar
Jingning Han committed
1
/*
2
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
Jingning Han's avatar
Jingning Han committed
3
 *
4
5
6
7
8
9
 * 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.
Jingning Han's avatar
Jingning Han committed
10
11
 */

12
13
14
#include "av1/common/common.h"
#include "av1/common/pred_common.h"
#include "av1/common/reconinter.h"
hui su's avatar
hui su committed
15
16
17
#if CONFIG_EXT_INTRA
#include "av1/common/reconintra.h"
#endif  // CONFIG_EXT_INTRA
18
#include "av1/common/seg_common.h"
Jingning Han's avatar
Jingning Han committed
19
20

// Returns a context number for the given MB prediction signal
21
#if CONFIG_DUAL_FILTER
James Zern's avatar
James Zern committed
22
23
24
25
static InterpFilter get_ref_filter_type(const MODE_INFO *mi,
                                        const MACROBLOCKD *xd, int dir,
                                        MV_REFERENCE_FRAME ref_frame) {
  InterpFilter ref_type = SWITCHABLE_FILTERS;
26
27
  const MB_MODE_INFO *ref_mbmi = &mi->mbmi;
  int use_subpel[2] = {
clang-format's avatar
clang-format committed
28
29
    has_subpel_mv_component(mi, xd, dir),
    has_subpel_mv_component(mi, xd, dir + 2),
30
31
32
33
34
35
36
37
38
39
  };

  if (ref_mbmi->ref_frame[0] == ref_frame && use_subpel[0])
    ref_type = ref_mbmi->interp_filter[(dir & 0x01)];
  else if (ref_mbmi->ref_frame[1] == ref_frame && use_subpel[1])
    ref_type = ref_mbmi->interp_filter[(dir & 0x01) + 2];

  return ref_type;
}

Yaowu Xu's avatar
Yaowu Xu committed
40
int av1_get_pred_context_switchable_interp(const MACROBLOCKD *xd, int dir) {
41
  const MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
42
43
  const int ctx_offset =
      (mbmi->ref_frame[1] > INTRA_FRAME) * INTER_FILTER_COMP_OFFSET;
clang-format's avatar
clang-format committed
44
45
  MV_REFERENCE_FRAME ref_frame =
      (dir < 2) ? mbmi->ref_frame[0] : mbmi->ref_frame[1];
46
47
48
49
  // Note:
  // The mode info data structure has a one element border above and to the
  // left of the entries corresponding to real macroblocks.
  // The prediction flags in these dummy entries are initialized to 0.
50
  int filter_type_ctx = ctx_offset + (dir & 0x01) * INTER_FILTER_DIR_OFFSET;
51
52
53
  int left_type = SWITCHABLE_FILTERS;
  int above_type = SWITCHABLE_FILTERS;

54
  if (xd->left_available)
55
    left_type = get_ref_filter_type(xd->mi[-1], xd, dir, ref_frame);
56

57
  if (xd->up_available)
clang-format's avatar
clang-format committed
58
59
    above_type =
        get_ref_filter_type(xd->mi[-xd->mi_stride], xd, dir, ref_frame);
60

61
  if (left_type == above_type) {
62
    filter_type_ctx += left_type;
63
64
  } else if (left_type == SWITCHABLE_FILTERS) {
    assert(above_type != SWITCHABLE_FILTERS);
65
    filter_type_ctx += above_type;
66
67
  } else if (above_type == SWITCHABLE_FILTERS) {
    assert(left_type != SWITCHABLE_FILTERS);
68
    filter_type_ctx += left_type;
69
  } else {
70
    filter_type_ctx += SWITCHABLE_FILTERS;
71
  }
72
73

  return filter_type_ctx;
74
75
}
#else
Yaowu Xu's avatar
Yaowu Xu committed
76
int av1_get_pred_context_switchable_interp(const MACROBLOCKD *xd) {
Jingning Han's avatar
Jingning Han committed
77
78
  // Note:
  // The mode info data structure has a one element border above and to the
hui su's avatar
hui su committed
79
80
  // left of the entries corresponding to real macroblocks.
  // The prediction flags in these dummy entries are initialized to 0.
Jingning Han's avatar
Jingning Han committed
81
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
clang-format's avatar
clang-format committed
82
83
84
  const int left_type = xd->left_available && is_inter_block(left_mbmi)
                            ? left_mbmi->interp_filter
                            : SWITCHABLE_FILTERS;
Jingning Han's avatar
Jingning Han committed
85
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
clang-format's avatar
clang-format committed
86
87
88
  const int above_type = xd->up_available && is_inter_block(above_mbmi)
                             ? above_mbmi->interp_filter
                             : SWITCHABLE_FILTERS;
Jingning Han's avatar
Jingning Han committed
89

90
  if (left_type == above_type) {
Jingning Han's avatar
Jingning Han committed
91
    return left_type;
92
93
  } else if (left_type == SWITCHABLE_FILTERS) {
    assert(above_type != SWITCHABLE_FILTERS);
Jingning Han's avatar
Jingning Han committed
94
    return above_type;
95
96
  } else if (above_type == SWITCHABLE_FILTERS) {
    assert(left_type != SWITCHABLE_FILTERS);
Jingning Han's avatar
Jingning Han committed
97
    return left_type;
98
  } else {
Jingning Han's avatar
Jingning Han committed
99
    return SWITCHABLE_FILTERS;
100
  }
Jingning Han's avatar
Jingning Han committed
101
}
102
#endif
Jingning Han's avatar
Jingning Han committed
103

104
#if CONFIG_EXT_INTRA
hui su's avatar
hui su committed
105
#if CONFIG_INTRA_INTERP
106
107
108
// Obtain the reference filter type from the above/left neighbor blocks.
static INTRA_FILTER get_ref_intra_filter(const MB_MODE_INFO *ref_mbmi) {
  INTRA_FILTER ref_type = INTRA_FILTERS;
109

110
  if (ref_mbmi->sb_type >= BLOCK_8X8) {
hui su's avatar
hui su committed
111
    const PREDICTION_MODE mode = ref_mbmi->mode;
112
    if (is_inter_block(ref_mbmi)) {
113
114
115
#if CONFIG_DUAL_FILTER
      switch (ref_mbmi->interp_filter[0]) {
#else
116
      switch (ref_mbmi->interp_filter) {
117
#endif
clang-format's avatar
clang-format committed
118
119
120
121
122
        case EIGHTTAP_REGULAR: ref_type = INTRA_FILTER_8TAP; break;
        case EIGHTTAP_SMOOTH: ref_type = INTRA_FILTER_8TAP_SMOOTH; break;
        case MULTITAP_SHARP: ref_type = INTRA_FILTER_8TAP_SHARP; break;
        case BILINEAR: ref_type = INTRA_FILTERS; break;
        default: break;
123
124
      }
    } else {
hui su's avatar
hui su committed
125
      if (av1_is_directional_mode(mode, ref_mbmi->sb_type)) {
hui su's avatar
hui su committed
126
127
        const int p_angle =
            mode_to_angle_map[mode] + ref_mbmi->angle_delta[0] * ANGLE_STEP;
Yaowu Xu's avatar
Yaowu Xu committed
128
        if (av1_is_intra_filter_switchable(p_angle)) {
129
          ref_type = ref_mbmi->intra_filter;
130
131
132
133
        }
      }
    }
  }
134
135
  return ref_type;
}
136

Yaowu Xu's avatar
Yaowu Xu committed
137
int av1_get_pred_context_intra_interp(const MACROBLOCKD *xd) {
138
139
  int left_type = INTRA_FILTERS, above_type = INTRA_FILTERS;

clang-format's avatar
clang-format committed
140
  if (xd->left_available) left_type = get_ref_intra_filter(xd->left_mbmi);
141

clang-format's avatar
clang-format committed
142
  if (xd->up_available) above_type = get_ref_intra_filter(xd->above_mbmi);
143
144
145
146
147
148
149
150
151
152

  if (left_type == above_type)
    return left_type;
  else if (left_type == INTRA_FILTERS && above_type != INTRA_FILTERS)
    return above_type;
  else if (left_type != INTRA_FILTERS && above_type == INTRA_FILTERS)
    return left_type;
  else
    return INTRA_FILTERS;
}
hui su's avatar
hui su committed
153
#endif  // CONFIG_INTRA_INTERP
154
155
#endif  // CONFIG_EXT_INTRA

156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
#if CONFIG_PALETTE && CONFIG_PALETTE_DELTA_ENCODING
int av1_get_palette_cache(const MODE_INFO *above_mi, const MODE_INFO *left_mi,
                          int plane, uint16_t *cache) {
  int above_n = 0, left_n = 0;
  if (above_mi)
    above_n = above_mi->mbmi.palette_mode_info.palette_size[plane != 0];
  if (left_mi)
    left_n = left_mi->mbmi.palette_mode_info.palette_size[plane != 0];
  if (above_n == 0 && left_n == 0) return 0;
  int above_idx = plane * PALETTE_MAX_SIZE;
  int left_idx = plane * PALETTE_MAX_SIZE;
  int n = 0;
  const uint16_t *above_colors =
      above_mi->mbmi.palette_mode_info.palette_colors;
  const uint16_t *left_colors = left_mi->mbmi.palette_mode_info.palette_colors;
  // Merge the sorted lists of base colors from above and left to get
  // combined sorted color cache.
  while (above_n > 0 && left_n > 0) {
    uint16_t v_above = above_colors[above_idx];
    uint16_t v_left = left_colors[left_idx];
    if (v_left < v_above) {
      if (n == 0 || v_left != cache[n - 1]) cache[n++] = v_left;
      ++left_idx, --left_n;
    } else {
      if (n == 0 || v_above != cache[n - 1]) cache[n++] = v_above;
      ++above_idx, --above_n;
      if (v_left == v_above) ++left_idx, --left_n;
    }
  }
  while (above_n-- > 0) {
    uint16_t val = above_colors[above_idx++];
    if (n == 0 || val != cache[n - 1]) cache[n++] = val;
  }
  while (left_n-- > 0) {
    uint16_t val = left_colors[left_idx++];
    if (n == 0 || val != cache[n - 1]) cache[n++] = val;
  }
  assert(n <= 2 * PALETTE_MAX_SIZE);
  return n;
}
#endif  // CONFIG_PALETTE && CONFIG_PALETTE_DELTA_ENCODING

Jingning Han's avatar
Jingning Han committed
198
199
200
201
202
203
204
// The mode info data structure has a one element border above and to the
// left of the entries corresponding to real macroblocks.
// The prediction flags in these dummy entries are initialized to 0.
// 0 - inter/inter, inter/--, --/inter, --/--
// 1 - intra/inter, inter/intra
// 2 - intra/--, --/intra
// 3 - intra/intra
Yaowu Xu's avatar
Yaowu Xu committed
205
int av1_get_intra_inter_context(const MACROBLOCKD *xd) {
Jingning Han's avatar
Jingning Han committed
206
207
208
209
210
211
212
213
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int has_above = xd->up_available;
  const int has_left = xd->left_available;

  if (has_above && has_left) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);
clang-format's avatar
clang-format committed
214
    return left_intra && above_intra ? 3 : left_intra || above_intra;
Jingning Han's avatar
Jingning Han committed
215
216
217
218
219
220
221
  } else if (has_above || has_left) {  // one edge available
    return 2 * !is_inter_block(has_above ? above_mbmi : left_mbmi);
  } else {
    return 0;
  }
}

222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
#if CONFIG_EXT_INTER && CONFIG_COMPOUND_SINGLEREF
// The compound/single mode info data structure has one element border above and
// to the left of the entries corresponding to real macroblocks.
// The prediction flags in these dummy entries are initialized to 0.
// 0 - single/single
// 1 - single/--, --/single, --/--
// 2 - single/comp, comp/single
// 3 - comp/comp, comp/--, --/comp
int av1_get_inter_mode_context(const MACROBLOCKD *xd) {
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int has_above = xd->up_available;
  const int has_left = xd->left_available;

  if (has_above && has_left) {  // both edges available (0/2/3)
    const int above_inter_comp_mode = is_inter_compound_mode(above_mbmi->mode);
    const int left_inter_comp_mode = is_inter_compound_mode(left_mbmi->mode);
    return (above_inter_comp_mode && left_inter_comp_mode)
               ? 3
               : (above_inter_comp_mode || left_inter_comp_mode) * 2;
  } else if (has_above || has_left) {  // one edge available (1/3)
    const MB_MODE_INFO *const edge_mbmi = has_above ? above_mbmi : left_mbmi;
    return is_inter_compound_mode(edge_mbmi->mode) ? 3 : 1;
  } else {  // no edge available (1)
    return 1;
  }
}
#endif  // CONFIG_EXT_INTER && CONFIG_COMPOUND_SINGLEREF

251
#if CONFIG_EXT_REFS
Zoe Liu's avatar
Zoe Liu committed
252
253
254
255
256
257
#define CHECK_BACKWARD_REFS(ref_frame) \
  (((ref_frame) >= BWDREF_FRAME) && ((ref_frame) <= ALTREF_FRAME))
#define IS_BACKWARD_REF_FRAME(ref_frame) CHECK_BACKWARD_REFS(ref_frame)
#else
#define IS_BACKWARD_REF_FRAME(ref_frame) ((ref_frame) == cm->comp_fixed_ref)
#endif  // CONFIG_EXT_REFS
258

Yaowu Xu's avatar
Yaowu Xu committed
259
260
int av1_get_reference_mode_context(const AV1_COMMON *cm,
                                   const MACROBLOCKD *xd) {
261
262
263
264
265
  int ctx;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int has_above = xd->up_available;
  const int has_left = xd->left_available;
266

Zoe Liu's avatar
Zoe Liu committed
267
#if CONFIG_EXT_REFS
268
  (void)cm;
Zoe Liu's avatar
Zoe Liu committed
269
#endif  // CONFIG_EXT_REFS
270

271
272
273
274
275
276
277
  // Note:
  // The mode info data structure has a one element border above and to the
  // left of the entries corresponding to real macroblocks.
  // The prediction flags in these dummy entries are initialized to 0.
  if (has_above && has_left) {  // both edges available
    if (!has_second_ref(above_mbmi) && !has_second_ref(left_mbmi))
      // neither edge uses comp pred (0/1)
Zoe Liu's avatar
Zoe Liu committed
278
279
      ctx = IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ^
            IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]);
Jingning Han's avatar
Jingning Han committed
280
281
    else if (!has_second_ref(above_mbmi))
      // one of two edges uses comp pred (2/3)
Zoe Liu's avatar
Zoe Liu committed
282
      ctx = 2 + (IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ||
Jingning Han's avatar
Jingning Han committed
283
284
285
                 !is_inter_block(above_mbmi));
    else if (!has_second_ref(left_mbmi))
      // one of two edges uses comp pred (2/3)
Zoe Liu's avatar
Zoe Liu committed
286
      ctx = 2 + (IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]) ||
Jingning Han's avatar
Jingning Han committed
287
288
289
290
291
292
293
294
                 !is_inter_block(left_mbmi));
    else  // both edges use comp pred (4)
      ctx = 4;
  } else if (has_above || has_left) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;

    if (!has_second_ref(edge_mbmi))
      // edge does not use comp pred (0/1)
Zoe Liu's avatar
Zoe Liu committed
295
      ctx = IS_BACKWARD_REF_FRAME(edge_mbmi->ref_frame[0]);
Jingning Han's avatar
Jingning Han committed
296
297
298
299
300
301
302
303
304
305
    else
      // edge uses comp pred (3)
      ctx = 3;
  } else {  // no edges available (1)
    ctx = 1;
  }
  assert(ctx >= 0 && ctx < COMP_INTER_CONTEXTS);
  return ctx;
}

306
307
308
#if CONFIG_EXT_REFS

// TODO(zoeliu): Future work will be conducted to optimize the context design
309
//               for the coding of the reference frames.
310
311
312
313

#define CHECK_LAST_OR_LAST2(ref_frame) \
  ((ref_frame == LAST_FRAME) || (ref_frame == LAST2_FRAME))

314
315
#define CHECK_GOLDEN_OR_LAST3(ref_frame) \
  ((ref_frame == GOLDEN_FRAME) || (ref_frame == LAST3_FRAME))
316

Jingning Han's avatar
Jingning Han committed
317
// Returns a context number for the given MB prediction signal
318
319
// Signal the first reference frame for a compound mode be either
// GOLDEN/LAST3, or LAST/LAST2.
320
321
//
// NOTE(zoeliu): The probability of ref_frame[0] is either
322
//               GOLDEN_FRAME or LAST3_FRAME.
323
324
325
326
#if CONFIG_LOWDELAY_COMPOUND
int av1_get_pred_context_comp_ref_p(UNUSED const AV1_COMMON *cm,
                                    const MACROBLOCKD *xd) {
#else
Yaowu Xu's avatar
Yaowu Xu committed
327
328
int av1_get_pred_context_comp_ref_p(const AV1_COMMON *cm,
                                    const MACROBLOCKD *xd) {
329
#endif
330
331
332
333
334
335
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int above_in_image = xd->up_available;
  const int left_in_image = xd->left_available;

336
337
338
339
340
341
342
343
// Note:
// The mode info data structure has a one element border above and to the
// left of the entries correpsonding to real macroblocks.
// The prediction flags in these dummy entries are initialised to 0.
#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
  const int bwd_ref_sign_idx = 1;
#else
344
  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
345
#endif
346
  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
347
348
349
350
351
352
353
354
355
356
357

  if (above_in_image && left_in_image) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra (2)
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
clang-format's avatar
clang-format committed
358
359
        pred_context =
            1 + 2 * (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]));
360
      else  // comp pred (1/3)
clang-format's avatar
clang-format committed
361
362
363
        pred_context = 1 +
                       2 * (!CHECK_GOLDEN_OR_LAST3(
                               edge_mbmi->ref_frame[fwd_ref_sign_idx]));
364
365
366
    } else {  // inter/inter
      const int l_sg = !has_second_ref(left_mbmi);
      const int a_sg = !has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
367
368
369
370
371
372
      const MV_REFERENCE_FRAME frfa =
          a_sg ? above_mbmi->ref_frame[0]
               : above_mbmi->ref_frame[fwd_ref_sign_idx];
      const MV_REFERENCE_FRAME frfl =
          l_sg ? left_mbmi->ref_frame[0]
               : left_mbmi->ref_frame[fwd_ref_sign_idx];
373

374
      if (frfa == frfl && CHECK_GOLDEN_OR_LAST3(frfa)) {
375
376
        pred_context = 0;
      } else if (l_sg && a_sg) {  // single/single
Zoe Liu's avatar
Zoe Liu committed
377
378
        if ((CHECK_BACKWARD_REFS(frfa) && CHECK_LAST_OR_LAST2(frfl)) ||
            (CHECK_BACKWARD_REFS(frfl) && CHECK_LAST_OR_LAST2(frfa))) {
379
          pred_context = 4;
clang-format's avatar
clang-format committed
380
        } else if (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl)) {
381
          pred_context = 1;
382
383
        } else {
          pred_context = 3;
384
385
        }
      } else if (l_sg || a_sg) {  // single/comp
386
387
        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
388

389
        if (CHECK_GOLDEN_OR_LAST3(frfc) && !CHECK_GOLDEN_OR_LAST3(rfs))
390
          pred_context = 1;
391
        else if (CHECK_GOLDEN_OR_LAST3(rfs) && !CHECK_GOLDEN_OR_LAST3(frfc))
392
393
394
395
          pred_context = 2;
        else
          pred_context = 4;
      } else {  // comp/comp
396
        if ((CHECK_LAST_OR_LAST2(frfa) && CHECK_LAST_OR_LAST2(frfl))) {
397
398
399
          pred_context = 4;
        } else {
          // NOTE(zoeliu): Following assert may be removed once confirmed.
400
          assert(CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl));
401
402
403
404
405
406
407
408
409
410
411
          pred_context = 2;
        }
      }
    }
  } else if (above_in_image || left_in_image) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi)) {
      pred_context = 2;
    } else {
      if (has_second_ref(edge_mbmi))
clang-format's avatar
clang-format committed
412
413
        pred_context =
            4 *
414
            (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[fwd_ref_sign_idx]));
415
      else
416
        pred_context = 3 * (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]));
417
418
419
420
421
422
423
424
425
426
427
    }
  } else {  // no edges available (2)
    pred_context = 2;
  }

  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);

  return pred_context;
}

// Returns a context number for the given MB prediction signal
428
// Signal the first reference frame for a compound mode be LAST,
429
430
431
432
// conditioning on that it is known either LAST/LAST2.
//
// NOTE(zoeliu): The probability of ref_frame[0] is LAST_FRAME,
// conditioning on it is either LAST_FRAME or LAST2_FRAME.
433
434
435
436
#if CONFIG_LOWDELAY_COMPOUND
int av1_get_pred_context_comp_ref_p1(UNUSED const AV1_COMMON *cm,
                                     const MACROBLOCKD *xd) {
#else
Yaowu Xu's avatar
Yaowu Xu committed
437
438
int av1_get_pred_context_comp_ref_p1(const AV1_COMMON *cm,
                                     const MACROBLOCKD *xd) {
439
#endif
440
441
442
443
444
445
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int above_in_image = xd->up_available;
  const int left_in_image = xd->left_available;

446
447
448
449
450
451
452
453
// Note:
// The mode info data structure has a one element border above and to the
// left of the entries correpsonding to real macroblocks.
// The prediction flags in these dummy entries are initialised to 0.
#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
  const int bwd_ref_sign_idx = 1;
#else
454
  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
455
#endif
456
  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
457
458
459
460
461
462
463
464
465
466
467
468
469

  if (above_in_image && left_in_image) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra (2)
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != LAST_FRAME);
      else  // comp pred (1/3)
clang-format's avatar
clang-format committed
470
471
        pred_context =
            1 + 2 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != LAST_FRAME);
472
473
474
    } else {  // inter/inter
      const int l_sg = !has_second_ref(left_mbmi);
      const int a_sg = !has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
475
476
477
478
479
480
      const MV_REFERENCE_FRAME frfa =
          a_sg ? above_mbmi->ref_frame[0]
               : above_mbmi->ref_frame[fwd_ref_sign_idx];
      const MV_REFERENCE_FRAME frfl =
          l_sg ? left_mbmi->ref_frame[0]
               : left_mbmi->ref_frame[fwd_ref_sign_idx];
481

482
      if (frfa == frfl && frfa == LAST_FRAME)
483
484
        pred_context = 0;
      else if (l_sg && a_sg) {  // single/single
485
        if (frfa == LAST_FRAME || frfl == LAST_FRAME)
486
          pred_context = 1;
487
488
489
        else if (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl))
          pred_context = 2 + (frfa != frfl);
        else if (frfa == frfl ||
Zoe Liu's avatar
Zoe Liu committed
490
                 (CHECK_BACKWARD_REFS(frfa) && CHECK_BACKWARD_REFS(frfl)))
491
492
493
494
          pred_context = 3;
        else
          pred_context = 4;
      } else if (l_sg || a_sg) {  // single/comp
495
496
        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
497

498
        if (frfc == LAST_FRAME && rfs != LAST_FRAME)
499
          pred_context = 1;
500
        else if (rfs == LAST_FRAME && frfc != LAST_FRAME)
501
502
          pred_context = 2;
        else
clang-format's avatar
clang-format committed
503
504
          pred_context =
              3 + (frfc == LAST2_FRAME || CHECK_GOLDEN_OR_LAST3(rfs));
505
      } else {  // comp/comp
506
        if (frfa == LAST_FRAME || frfl == LAST_FRAME)
507
508
          pred_context = 2;
        else
clang-format's avatar
clang-format committed
509
510
          pred_context =
              3 + (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl));
511
512
513
514
515
516
517
518
519
      }
    }
  } else if (above_in_image || left_in_image) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi)) {
      pred_context = 2;
    } else {
      if (has_second_ref(edge_mbmi)) {
clang-format's avatar
clang-format committed
520
521
        pred_context =
            4 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != LAST_FRAME);
522
523
524
525
      } else {
        if (edge_mbmi->ref_frame[0] == LAST_FRAME)
          pred_context = 0;
        else
526
          pred_context = 2 + CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]);
527
528
529
530
531
532
533
534
535
536
537
538
      }
    }
  } else {  // no edges available (2)
    pred_context = 2;
  }

  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);

  return pred_context;
}

// Returns a context number for the given MB prediction signal
539
540
// Signal the first reference frame for a compound mode be GOLDEN,
// conditioning on that it is known either GOLDEN or LAST3.
541
542
//
// NOTE(zoeliu): The probability of ref_frame[0] is GOLDEN_FRAME,
543
// conditioning on it is either GOLDEN or LAST3.
544
545
546
547
#if CONFIG_LOWDELAY_COMPOUND
int av1_get_pred_context_comp_ref_p2(UNUSED const AV1_COMMON *cm,
                                     const MACROBLOCKD *xd) {
#else
Yaowu Xu's avatar
Yaowu Xu committed
548
549
int av1_get_pred_context_comp_ref_p2(const AV1_COMMON *cm,
                                     const MACROBLOCKD *xd) {
550
#endif
551
552
553
554
555
556
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int above_in_image = xd->up_available;
  const int left_in_image = xd->left_available;

557
558
559
560
561
562
563
564
// Note:
// The mode info data structure has a one element border above and to the
// left of the entries correpsonding to real macroblocks.
// The prediction flags in these dummy entries are initialised to 0.
#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
  const int bwd_ref_sign_idx = 1;
#else
565
  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
566
#endif
567
  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
568
569
570
571
572
573
574
575
576
577
578
579
580

  if (above_in_image && left_in_image) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra (2)
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != GOLDEN_FRAME);
      else  // comp pred (1/3)
clang-format's avatar
clang-format committed
581
582
        pred_context =
            1 + 2 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != GOLDEN_FRAME);
583
584
585
    } else {  // inter/inter
      const int l_sg = !has_second_ref(left_mbmi);
      const int a_sg = !has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
586
587
588
589
590
591
      const MV_REFERENCE_FRAME frfa =
          a_sg ? above_mbmi->ref_frame[0]
               : above_mbmi->ref_frame[fwd_ref_sign_idx];
      const MV_REFERENCE_FRAME frfl =
          l_sg ? left_mbmi->ref_frame[0]
               : left_mbmi->ref_frame[fwd_ref_sign_idx];
592

593
      if (frfa == frfl && frfa == GOLDEN_FRAME)
594
595
        pred_context = 0;
      else if (l_sg && a_sg) {  // single/single
596
        if (frfa == GOLDEN_FRAME || frfl == GOLDEN_FRAME)
597
          pred_context = 1;
598
599
600
        else if (CHECK_LAST_OR_LAST2(frfa) || CHECK_LAST_OR_LAST2(frfl))
          pred_context = 2 + (frfa != frfl);
        else if (frfa == frfl ||
Zoe Liu's avatar
Zoe Liu committed
601
                 (CHECK_BACKWARD_REFS(frfa) && CHECK_BACKWARD_REFS(frfl)))
602
603
604
605
          pred_context = 3;
        else
          pred_context = 4;
      } else if (l_sg || a_sg) {  // single/comp
606
607
        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
608

609
        if (frfc == GOLDEN_FRAME && rfs != GOLDEN_FRAME)
610
          pred_context = 1;
611
        else if (rfs == GOLDEN_FRAME && frfc != GOLDEN_FRAME)
612
613
          pred_context = 2;
        else
clang-format's avatar
clang-format committed
614
          pred_context = 3 + (frfc == LAST3_FRAME || CHECK_LAST_OR_LAST2(rfs));
615
      } else {  // comp/comp
616
        if (frfa == GOLDEN_FRAME || frfl == GOLDEN_FRAME)
617
618
          pred_context = 2;
        else
clang-format's avatar
clang-format committed
619
620
          pred_context =
              3 + (CHECK_LAST_OR_LAST2(frfa) || CHECK_LAST_OR_LAST2(frfl));
621
622
623
624
625
626
627
628
629
      }
    }
  } else if (above_in_image || left_in_image) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi)) {
      pred_context = 2;
    } else {
      if (has_second_ref(edge_mbmi)) {
clang-format's avatar
clang-format committed
630
631
        pred_context =
            4 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != GOLDEN_FRAME);
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
      } else {
        if (edge_mbmi->ref_frame[0] == GOLDEN_FRAME)
          pred_context = 0;
        else
          pred_context = 2 + CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]);
      }
    }
  } else {  // no edges available (2)
    pred_context = 2;
  }

  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);

  return pred_context;
}

648
// Returns a context number for the given MB prediction signal
649
650
651
652
#if CONFIG_LOWDELAY_COMPOUND
int av1_get_pred_context_comp_bwdref_p(UNUSED const AV1_COMMON *cm,
                                       const MACROBLOCKD *xd) {
#else
Yaowu Xu's avatar
Yaowu Xu committed
653
654
int av1_get_pred_context_comp_bwdref_p(const AV1_COMMON *cm,
                                       const MACROBLOCKD *xd) {
655
#endif
656
657
658
659
660
661
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int above_in_image = xd->up_available;
  const int left_in_image = xd->left_available;

662
663
664
665
666
667
668
669
// Note:
// The mode info data structure has a one element border above and to the
// left of the entries corresponding to real macroblocks.
// The prediction flags in these dummy entries are initialized to 0.
#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
  const int bwd_ref_sign_idx = 1;
#else
670
  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
671
#endif
672
673
674
675
676
677
678
679
680
681
682
683
  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;

  if (above_in_image && left_in_image) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra (2)
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
684
        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != cm->comp_bwd_ref[1]);
685
      else  // comp pred (1/3)
clang-format's avatar
clang-format committed
686
687
688
        pred_context =
            1 +
            2 * (edge_mbmi->ref_frame[bwd_ref_sign_idx] != cm->comp_bwd_ref[1]);
689
690
691
692
    } else {  // inter/inter
      const int l_comp = has_second_ref(left_mbmi);
      const int a_comp = has_second_ref(above_mbmi);

clang-format's avatar
clang-format committed
693
      const MV_REFERENCE_FRAME l_brf =
Emil Keyder's avatar
Emil Keyder committed
694
          l_comp ? left_mbmi->ref_frame[bwd_ref_sign_idx] : NONE_FRAME;
clang-format's avatar
clang-format committed
695
      const MV_REFERENCE_FRAME a_brf =
Emil Keyder's avatar
Emil Keyder committed
696
          a_comp ? above_mbmi->ref_frame[bwd_ref_sign_idx] : NONE_FRAME;
697

clang-format's avatar
clang-format committed
698
699
700
701
702
703
      const MV_REFERENCE_FRAME l_frf =
          !l_comp ? left_mbmi->ref_frame[0]
                  : left_mbmi->ref_frame[fwd_ref_sign_idx];
      const MV_REFERENCE_FRAME a_frf =
          !a_comp ? above_mbmi->ref_frame[0]
                  : above_mbmi->ref_frame[fwd_ref_sign_idx];
704

705
      if (l_comp && a_comp) {  // comp/comp
706
707
708
709
710
711
712
713
714
715
        if (l_brf == a_brf && l_brf == cm->comp_bwd_ref[1]) {
          pred_context = 0;
        } else if (l_brf == cm->comp_bwd_ref[1] ||
                   a_brf == cm->comp_bwd_ref[1]) {
          pred_context = 1;
        } else {
          // NOTE: Backward ref should be either BWDREF or ALTREF.
          assert(l_brf == a_brf && l_brf != cm->comp_bwd_ref[1]);
          pred_context = 3;
        }
716
      } else if (!l_comp && !a_comp) {  // single/single
717
718
719
720
721
722
723
724
        if (l_frf == a_frf && l_frf == cm->comp_bwd_ref[1]) {
          pred_context = 0;
        } else if (l_frf == cm->comp_bwd_ref[1] ||
                   a_frf == cm->comp_bwd_ref[1]) {
          pred_context = 1;
        } else if (l_frf == a_frf) {
          pred_context = 3;
        } else {
clang-format's avatar
clang-format committed
725
726
          assert(l_frf != a_frf && l_frf != cm->comp_bwd_ref[1] &&
                 a_frf != cm->comp_bwd_ref[1]);
727
728
          pred_context = 4;
        }
729
      } else {  // comp/single
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
        assert((l_comp && !a_comp) || (!l_comp && a_comp));

        if ((l_comp && l_brf == cm->comp_bwd_ref[1] &&
             a_frf == cm->comp_bwd_ref[1]) ||
            (a_comp && a_brf == cm->comp_bwd_ref[1] &&
             l_frf == cm->comp_bwd_ref[1])) {
          pred_context = 1;
        } else if ((l_comp && l_brf == cm->comp_bwd_ref[1]) ||
                   (a_comp && a_brf == cm->comp_bwd_ref[1]) ||
                   (!l_comp && l_frf == cm->comp_bwd_ref[1]) ||
                   (!a_comp && a_frf == cm->comp_bwd_ref[1])) {
          pred_context = 2;
        } else {
          pred_context = 4;
        }
      }
    }
  } else if (above_in_image || left_in_image) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi)) {
      pred_context = 2;
    } else {
      if (has_second_ref(edge_mbmi)) {
clang-format's avatar
clang-format committed
754
755
        pred_context =
            4 * (edge_mbmi->ref_frame[bwd_ref_sign_idx] != cm->comp_bwd_ref[1]);
756
757
758
759
760
761
762
763
764
765
766
767
      } else {
        pred_context = 3 * (edge_mbmi->ref_frame[0] != cm->comp_bwd_ref[1]);
      }
    }
  } else {  // no edges available (2)
    pred_context = 2;
  }
  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);

  return pred_context;
}

768
#else  // CONFIG_EXT_REFS
769

770
// Returns a context number for the given MB prediction signal
Yaowu Xu's avatar
Yaowu Xu committed
771
772
int av1_get_pred_context_comp_ref_p(const AV1_COMMON *cm,
                                    const MACROBLOCKD *xd) {
773
774
775
776
777
778
779
780
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int above_in_image = xd->up_available;
  const int left_in_image = xd->left_available;

  // Note:
  // The mode info data structure has a one element border above and to the
781
782
  // left of the entries corresponding to real macroblocks.
  // The prediction flags in these dummy entries are initialized to 0.
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
  const int fix_ref_idx = cm->ref_frame_sign_bias[cm->comp_fixed_ref];
  const int var_ref_idx = !fix_ref_idx;

  if (above_in_image && left_in_image) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra (2)
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != cm->comp_var_ref[1]);
      else  // comp pred (1/3)
clang-format's avatar
clang-format committed
798
799
        pred_context =
            1 + 2 * (edge_mbmi->ref_frame[var_ref_idx] != cm->comp_var_ref[1]);
800
801
802
    } else {  // inter/inter
      const int l_sg = !has_second_ref(left_mbmi);
      const int a_sg = !has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
803
804
805
806
      const MV_REFERENCE_FRAME vrfa =
          a_sg ? above_mbmi->ref_frame[0] : above_mbmi->ref_frame[var_ref_idx];
      const MV_REFERENCE_FRAME vrfl =
          l_sg ? left_mbmi->ref_frame[0] : left_mbmi->ref_frame[var_ref_idx];
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839

      if (vrfa == vrfl && cm->comp_var_ref[1] == vrfa) {
        pred_context = 0;
      } else if (l_sg && a_sg) {  // single/single
        if ((vrfa == cm->comp_fixed_ref && vrfl == cm->comp_var_ref[0]) ||
            (vrfl == cm->comp_fixed_ref && vrfa == cm->comp_var_ref[0]))
          pred_context = 4;
        else if (vrfa == vrfl)
          pred_context = 3;
        else
          pred_context = 1;
      } else if (l_sg || a_sg) {  // single/comp
        const MV_REFERENCE_FRAME vrfc = l_sg ? vrfa : vrfl;
        const MV_REFERENCE_FRAME rfs = a_sg ? vrfa : vrfl;
        if (vrfc == cm->comp_var_ref[1] && rfs != cm->comp_var_ref[1])
          pred_context = 1;
        else if (rfs == cm->comp_var_ref[1] && vrfc != cm->comp_var_ref[1])
          pred_context = 2;
        else
          pred_context = 4;
      } else if (vrfa == vrfl) {  // comp/comp
        pred_context = 4;
      } else {
        pred_context = 2;
      }
    }
  } else if (above_in_image || left_in_image) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi)) {
      pred_context = 2;
    } else {
      if (has_second_ref(edge_mbmi))
clang-format's avatar
clang-format committed
840
841
        pred_context =
            4 * (edge_mbmi->ref_frame[var_ref_idx] != cm->comp_var_ref[1]);
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
      else
        pred_context = 3 * (edge_mbmi->ref_frame[0] != cm->comp_var_ref[1]);
    }
  } else {  // no edges available (2)
    pred_context = 2;
  }
  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);

  return pred_context;
}

#endif  // CONFIG_EXT_REFS

#if CONFIG_EXT_REFS

// For the bit to signal whether the single reference is a ALTREF_FRAME
858
// or a BWDREF_FRAME.
859
//
860
// NOTE(zoeliu): The probability of ref_frame[0] is ALTREF/BWDREF.
Yaowu Xu's avatar
Yaowu Xu committed
861
int av1_get_pred_context_single_ref_p1(const MACROBLOCKD *xd) {
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int has_above = xd->up_available;
  const int has_left = xd->left_available;

  // Note:
  // The mode info data structure has a one element border above and to the
  // left of the entries correpsonding to real macroblocks.
  // The prediction flags in these dummy entries are initialised to 0.
  if (has_above && has_left) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;

881
      if (!has_second_ref(edge_mbmi))  // single
Zoe Liu's avatar
Zoe Liu committed
882
        pred_context = 4 * (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]));
883
884
      else  // comp
        pred_context = 2;
885
886
    } else {  // inter/inter
      const int above_has_second = has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
887
      const int left_has_second = has_second_ref(left_mbmi);
888
889
890
891

      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];

892
893
894
      if (above_has_second && left_has_second) {  // comp/comp
        pred_context = 2;
      } else if (above_has_second || left_has_second) {  // single/comp
895
896
        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;

897
898
        pred_context = (!CHECK_BACKWARD_REFS(rfs)) ? 4 : 1;
      } else {  // single/single
Zoe Liu's avatar
Zoe Liu committed
899
900
        pred_context = 2 * (!CHECK_BACKWARD_REFS(above0)) +
                       2 * (!CHECK_BACKWARD_REFS(left0));
901
902
903
904
905
906
      }
    }
  } else if (has_above || has_left) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
    if (!is_inter_block(edge_mbmi)) {  // intra
      pred_context = 2;
907
908
    } else {                           // inter
      if (!has_second_ref(edge_mbmi))  // single
Zoe Liu's avatar
Zoe Liu committed
909
        pred_context = 4 * (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]));
910
911
      else  // comp
        pred_context = 2;
912
913
914
915
916
917
918
919
920
921
    }
  } else {  // no edges available
    pred_context = 2;
  }

  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
  return pred_context;
}

// For the bit to signal whether the single reference is ALTREF_FRAME or
922
// BWDREF_FRAME, knowing that it shall be either of these 2 choices.
923
924
//
// NOTE(zoeliu): The probability of ref_frame[0] is ALTREF_FRAME, conditioning
925
// on it is either ALTREF_FRAME/BWDREF_FRAME.
Yaowu Xu's avatar
Yaowu Xu committed
926
int av1_get_pred_context_single_ref_p2(const MACROBLOCKD *xd) {
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
  int pred_context;
  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
  const int has_above = xd->up_available;
  const int has_left = xd->left_available;

  // Note:
  // The mode info data structure has a one element border above and to the
  // left of the entries correpsonding to real macroblocks.
  // The prediction flags in these dummy entries are initialised to 0.
  if (has_above && has_left) {  // both edges available
    const int above_intra = !is_inter_block(above_mbmi);
    const int left_intra = !is_inter_block(left_mbmi);

    if (above_intra && left_intra) {  // intra/intra
      pred_context = 2;
    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
945
      if (!has_second_ref(edge_mbmi)) {  // single
Zoe Liu's avatar
Zoe Liu committed
946
        if (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]))
947
948
          pred_context = 3;
        else
949
          pred_context = 4 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME);
950
      } else {  // comp
clang-format's avatar
clang-format committed
951
952
953
        pred_context = 1 +
                       2 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME ||
                            edge_mbmi->ref_frame[1] == BWDREF_FRAME);
954
955
956
      }
    } else {  // inter/inter
      const int above_has_second = has_second_ref(above_mbmi);
clang-format's avatar
clang-format committed
957
      const int left_has_second = has_second_ref(left_mbmi);
958
959
960
961
962
      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];

963
      if (above_has_second && left_has_second) {  // comp/comp
964
        if (above0 == left0 && above1 == left1)
clang-format's avatar
clang-format committed
965
966
967
          pred_context =
              3 * (above0 == BWDREF_FRAME || above1 == BWDREF_FRAME ||
                   left0 == BWDREF_FRAME || left1 == BWDREF_FRAME);
968
969
        else
          pred_context = 2;
970
      } else if (above_has_second || left_has_second) {  // single/comp
971
972
973
974
        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;

975
976
        if (rfs == BWDREF_FRAME)
          pred_context = 3 + (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
977
        else if (rfs == ALTREF_FRAME)
978
          pred_context = (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
979
        else
980
          pred_context = 1 + 2 * (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
981
      } else {  // single/single
Zoe Liu's avatar
Zoe Liu committed
982
        if (!CHECK_BACKWARD_REFS(above0) && !CHECK_BACKWARD_REFS(left0)) {
983
          pred_context = 2 + (above0 == left0);
Zoe Liu's avatar
Zoe Liu committed
984
985
        } else if (!CHECK_BACKWARD_REFS(above0) ||
                   !CHECK_BACKWARD_REFS(left0)) {
986
          const MV_REFERENCE_FRAME edge0 =
Zoe Liu's avatar
Zoe Liu committed
987
              !CHECK_BACKWARD_REFS(above0) ? left0 : above0;
988
          pred_context = 4 * (edge0 == BWDREF_FRAME);
989
        } else {
clang-format's avatar
clang-format committed
990
991
          pred_context =
              2 * (above0 == BWDREF_FRAME) + 2 * (left0 == BWDREF_FRAME);
992
993
994
995
996
997
998
        }
      }
    }
  } else if (has_above || has_left) {  // one edge available
    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;

    if (!is_inter_block(edge_mbmi) ||
Zoe Liu's avatar
Zoe Liu committed
999
        (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]) &&
1000
         !has_second_ref(edge_mbmi)))