2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
15 #include "vpx/vpx_encoder.h"
16 #include "vpx_dsp/bitwriter_buffer.h"
17 #include "vpx_dsp/vpx_dsp_common.h"
18 #include "vpx_mem/vpx_mem.h"
19 #include "vpx_ports/mem_ops.h"
20 #include "vpx_ports/system_state.h"
22 #include "vp9/common/vp9_entropy.h"
23 #include "vp9/common/vp9_entropymode.h"
24 #include "vp9/common/vp9_entropymv.h"
25 #include "vp9/common/vp9_mvref_common.h"
26 #include "vp9/common/vp9_pred_common.h"
27 #include "vp9/common/vp9_seg_common.h"
28 #include "vp9/common/vp9_tile_common.h"
30 #include "vp9/encoder/vp9_cost.h"
31 #include "vp9/encoder/vp9_bitstream.h"
32 #include "vp9/encoder/vp9_encodemv.h"
33 #include "vp9/encoder/vp9_mcomp.h"
34 #include "vp9/encoder/vp9_segmentation.h"
35 #include "vp9/encoder/vp9_subexp.h"
36 #include "vp9/encoder/vp9_tokenize.h"
38 static const struct vp9_token intra_mode_encodings[INTRA_MODES] = {
39 {0, 1}, {6, 3}, {28, 5}, {30, 5}, {58, 6}, {59, 6}, {126, 7}, {127, 7},
41 static const struct vp9_token switchable_interp_encodings[SWITCHABLE_FILTERS] =
42 {{0, 1}, {2, 2}, {3, 2}};
43 static const struct vp9_token partition_encodings[PARTITION_TYPES] =
44 {{0, 1}, {2, 2}, {6, 3}, {7, 3}};
45 static const struct vp9_token inter_mode_encodings[INTER_MODES] =
46 {{2, 2}, {6, 3}, {0, 1}, {7, 3}};
48 static void write_intra_mode(vpx_writer *w, PREDICTION_MODE mode,
49 const vpx_prob *probs) {
50 vp9_write_token(w, vp9_intra_mode_tree, probs, &intra_mode_encodings[mode]);
53 static void write_inter_mode(vpx_writer *w, PREDICTION_MODE mode,
54 const vpx_prob *probs) {
55 assert(is_inter_mode(mode));
56 vp9_write_token(w, vp9_inter_mode_tree, probs,
57 &inter_mode_encodings[INTER_OFFSET(mode)]);
60 static void encode_unsigned_max(struct vpx_write_bit_buffer *wb,
62 vpx_wb_write_literal(wb, data, get_unsigned_bits(max));
65 static void prob_diff_update(const vpx_tree_index *tree,
66 vpx_prob probs[/*n - 1*/],
67 const unsigned int counts[/*n - 1*/],
68 int n, vpx_writer *w) {
70 unsigned int branch_ct[32][2];
72 // Assuming max number of probabilities <= 32
75 vp9_tree_probs_from_distribution(tree, branch_ct, counts);
76 for (i = 0; i < n - 1; ++i)
77 vp9_cond_prob_diff_update(w, &probs[i], branch_ct[i]);
80 static void write_selected_tx_size(const VP9_COMMON *cm,
81 const MACROBLOCKD *xd, vpx_writer *w) {
82 TX_SIZE tx_size = xd->mi[0]->mbmi.tx_size;
83 BLOCK_SIZE bsize = xd->mi[0]->mbmi.sb_type;
84 const TX_SIZE max_tx_size = max_txsize_lookup[bsize];
85 const vpx_prob *const tx_probs = get_tx_probs2(max_tx_size, xd,
87 vpx_write(w, tx_size != TX_4X4, tx_probs[0]);
88 if (tx_size != TX_4X4 && max_tx_size >= TX_16X16) {
89 vpx_write(w, tx_size != TX_8X8, tx_probs[1]);
90 if (tx_size != TX_8X8 && max_tx_size >= TX_32X32)
91 vpx_write(w, tx_size != TX_16X16, tx_probs[2]);
95 static int write_skip(const VP9_COMMON *cm, const MACROBLOCKD *xd,
96 int segment_id, const MODE_INFO *mi, vpx_writer *w) {
97 if (segfeature_active(&cm->seg, segment_id, SEG_LVL_SKIP)) {
100 const int skip = mi->mbmi.skip;
101 vpx_write(w, skip, vp9_get_skip_prob(cm, xd));
106 static void update_skip_probs(VP9_COMMON *cm, vpx_writer *w,
107 FRAME_COUNTS *counts) {
110 for (k = 0; k < SKIP_CONTEXTS; ++k)
111 vp9_cond_prob_diff_update(w, &cm->fc->skip_probs[k], counts->skip[k]);
114 static void update_switchable_interp_probs(VP9_COMMON *cm, vpx_writer *w,
115 FRAME_COUNTS *counts) {
117 for (j = 0; j < SWITCHABLE_FILTER_CONTEXTS; ++j)
118 prob_diff_update(vp9_switchable_interp_tree,
119 cm->fc->switchable_interp_prob[j],
120 counts->switchable_interp[j], SWITCHABLE_FILTERS, w);
123 static void pack_mb_tokens(vpx_writer *w,
124 TOKENEXTRA **tp, const TOKENEXTRA *const stop,
125 vpx_bit_depth_t bit_depth) {
128 while (p < stop && p->token != EOSB_TOKEN) {
129 const int t = p->token;
130 const struct vp9_token *const a = &vp9_coef_encodings[t];
134 #if CONFIG_VP9_HIGHBITDEPTH
135 const vp9_extra_bit *b;
136 if (bit_depth == VPX_BITS_12)
137 b = &vp9_extra_bits_high12[t];
138 else if (bit_depth == VPX_BITS_10)
139 b = &vp9_extra_bits_high10[t];
141 b = &vp9_extra_bits[t];
143 const vp9_extra_bit *const b = &vp9_extra_bits[t];
145 #endif // CONFIG_VP9_HIGHBITDEPTH
147 /* skip one or two nodes */
148 if (p->skip_eob_node) {
149 n -= p->skip_eob_node;
150 i = 2 * p->skip_eob_node;
153 // TODO(jbb): expanding this can lead to big gains. It allows
154 // much better branch prediction and would enable us to avoid numerous
155 // lookups and compares.
157 // If we have a token that's in the constrained set, the coefficient tree
158 // is split into two treed writes. The first treed write takes care of the
159 // unconstrained nodes. The second treed write takes care of the
160 // constrained nodes.
161 if (t >= TWO_TOKEN && t < EOB_TOKEN) {
162 int len = UNCONSTRAINED_NODES - p->skip_eob_node;
163 int bits = v >> (n - len);
164 vp9_write_tree(w, vp9_coef_tree, p->context_tree, bits, len, i);
165 vp9_write_tree(w, vp9_coef_con_tree,
166 vp9_pareto8_full[p->context_tree[PIVOT_NODE] - 1],
169 vp9_write_tree(w, vp9_coef_tree, p->context_tree, v, n, i);
173 const int e = p->extra, l = b->len;
176 const unsigned char *pb = b->prob;
178 int n = l; /* number of bits in v, assumed nonzero */
182 const int bb = (v >> --n) & 1;
183 vpx_write(w, bb, pb[i >> 1]);
188 vpx_write_bit(w, e & 1);
193 *tp = p + (p->token == EOSB_TOKEN);
196 static void write_segment_id(vpx_writer *w, const struct segmentation *seg,
198 if (seg->enabled && seg->update_map)
199 vp9_write_tree(w, vp9_segment_tree, seg->tree_probs, segment_id, 3, 0);
202 // This function encodes the reference frame
203 static void write_ref_frames(const VP9_COMMON *cm, const MACROBLOCKD *xd,
205 const MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
206 const int is_compound = has_second_ref(mbmi);
207 const int segment_id = mbmi->segment_id;
209 // If segment level coding of this signal is disabled...
210 // or the segment allows multiple reference frame options
211 if (segfeature_active(&cm->seg, segment_id, SEG_LVL_REF_FRAME)) {
212 assert(!is_compound);
213 assert(mbmi->ref_frame[0] ==
214 get_segdata(&cm->seg, segment_id, SEG_LVL_REF_FRAME));
216 // does the feature use compound prediction or not
217 // (if not specified at the frame/segment level)
218 if (cm->reference_mode == REFERENCE_MODE_SELECT) {
219 vpx_write(w, is_compound, vp9_get_reference_mode_prob(cm, xd));
221 assert(!is_compound == (cm->reference_mode == SINGLE_REFERENCE));
225 vpx_write(w, mbmi->ref_frame[0] == GOLDEN_FRAME,
226 vp9_get_pred_prob_comp_ref_p(cm, xd));
228 const int bit0 = mbmi->ref_frame[0] != LAST_FRAME;
229 vpx_write(w, bit0, vp9_get_pred_prob_single_ref_p1(cm, xd));
231 const int bit1 = mbmi->ref_frame[0] != GOLDEN_FRAME;
232 vpx_write(w, bit1, vp9_get_pred_prob_single_ref_p2(cm, xd));
238 static void pack_inter_mode_mvs(VP9_COMP *cpi, const MODE_INFO *mi,
240 VP9_COMMON *const cm = &cpi->common;
241 const nmv_context *nmvc = &cm->fc->nmvc;
242 const MACROBLOCK *const x = &cpi->td.mb;
243 const MACROBLOCKD *const xd = &x->e_mbd;
244 const struct segmentation *const seg = &cm->seg;
245 const MB_MODE_INFO *const mbmi = &mi->mbmi;
246 const MB_MODE_INFO_EXT *const mbmi_ext = x->mbmi_ext;
247 const PREDICTION_MODE mode = mbmi->mode;
248 const int segment_id = mbmi->segment_id;
249 const BLOCK_SIZE bsize = mbmi->sb_type;
250 const int allow_hp = cm->allow_high_precision_mv;
251 const int is_inter = is_inter_block(mbmi);
252 const int is_compound = has_second_ref(mbmi);
255 if (seg->update_map) {
256 if (seg->temporal_update) {
257 const int pred_flag = mbmi->seg_id_predicted;
258 vpx_prob pred_prob = vp9_get_pred_prob_seg_id(seg, xd);
259 vpx_write(w, pred_flag, pred_prob);
261 write_segment_id(w, seg, segment_id);
263 write_segment_id(w, seg, segment_id);
267 skip = write_skip(cm, xd, segment_id, mi, w);
269 if (!segfeature_active(seg, segment_id, SEG_LVL_REF_FRAME))
270 vpx_write(w, is_inter, vp9_get_intra_inter_prob(cm, xd));
272 if (bsize >= BLOCK_8X8 && cm->tx_mode == TX_MODE_SELECT &&
273 !(is_inter && skip)) {
274 write_selected_tx_size(cm, xd, w);
278 if (bsize >= BLOCK_8X8) {
279 write_intra_mode(w, mode, cm->fc->y_mode_prob[size_group_lookup[bsize]]);
282 const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];
283 const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];
284 for (idy = 0; idy < 2; idy += num_4x4_h) {
285 for (idx = 0; idx < 2; idx += num_4x4_w) {
286 const PREDICTION_MODE b_mode = mi->bmi[idy * 2 + idx].as_mode;
287 write_intra_mode(w, b_mode, cm->fc->y_mode_prob[0]);
291 write_intra_mode(w, mbmi->uv_mode, cm->fc->uv_mode_prob[mode]);
293 const int mode_ctx = mbmi_ext->mode_context[mbmi->ref_frame[0]];
294 const vpx_prob *const inter_probs = cm->fc->inter_mode_probs[mode_ctx];
295 write_ref_frames(cm, xd, w);
297 // If segment skip is not enabled code the mode.
298 if (!segfeature_active(seg, segment_id, SEG_LVL_SKIP)) {
299 if (bsize >= BLOCK_8X8) {
300 write_inter_mode(w, mode, inter_probs);
304 if (cm->interp_filter == SWITCHABLE) {
305 const int ctx = vp9_get_pred_context_switchable_interp(xd);
306 vp9_write_token(w, vp9_switchable_interp_tree,
307 cm->fc->switchable_interp_prob[ctx],
308 &switchable_interp_encodings[mbmi->interp_filter]);
309 ++cpi->interp_filter_selected[0][mbmi->interp_filter];
311 assert(mbmi->interp_filter == cm->interp_filter);
314 if (bsize < BLOCK_8X8) {
315 const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];
316 const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];
318 for (idy = 0; idy < 2; idy += num_4x4_h) {
319 for (idx = 0; idx < 2; idx += num_4x4_w) {
320 const int j = idy * 2 + idx;
321 const PREDICTION_MODE b_mode = mi->bmi[j].as_mode;
322 write_inter_mode(w, b_mode, inter_probs);
323 if (b_mode == NEWMV) {
324 for (ref = 0; ref < 1 + is_compound; ++ref)
325 vp9_encode_mv(cpi, w, &mi->bmi[j].as_mv[ref].as_mv,
326 &mbmi_ext->ref_mvs[mbmi->ref_frame[ref]][0].as_mv,
333 for (ref = 0; ref < 1 + is_compound; ++ref)
334 vp9_encode_mv(cpi, w, &mbmi->mv[ref].as_mv,
335 &mbmi_ext->ref_mvs[mbmi->ref_frame[ref]][0].as_mv, nmvc,
342 static void write_mb_modes_kf(const VP9_COMMON *cm, const MACROBLOCKD *xd,
343 MODE_INFO **mi_8x8, vpx_writer *w) {
344 const struct segmentation *const seg = &cm->seg;
345 const MODE_INFO *const mi = mi_8x8[0];
346 const MODE_INFO *const above_mi = xd->above_mi;
347 const MODE_INFO *const left_mi = xd->left_mi;
348 const MB_MODE_INFO *const mbmi = &mi->mbmi;
349 const BLOCK_SIZE bsize = mbmi->sb_type;
352 write_segment_id(w, seg, mbmi->segment_id);
354 write_skip(cm, xd, mbmi->segment_id, mi, w);
356 if (bsize >= BLOCK_8X8 && cm->tx_mode == TX_MODE_SELECT)
357 write_selected_tx_size(cm, xd, w);
359 if (bsize >= BLOCK_8X8) {
360 write_intra_mode(w, mbmi->mode, get_y_mode_probs(mi, above_mi, left_mi, 0));
362 const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];
363 const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];
366 for (idy = 0; idy < 2; idy += num_4x4_h) {
367 for (idx = 0; idx < 2; idx += num_4x4_w) {
368 const int block = idy * 2 + idx;
369 write_intra_mode(w, mi->bmi[block].as_mode,
370 get_y_mode_probs(mi, above_mi, left_mi, block));
375 write_intra_mode(w, mbmi->uv_mode, vp9_kf_uv_mode_prob[mbmi->mode]);
378 static void write_modes_b(VP9_COMP *cpi, const TileInfo *const tile,
379 vpx_writer *w, TOKENEXTRA **tok,
380 const TOKENEXTRA *const tok_end,
381 int mi_row, int mi_col) {
382 const VP9_COMMON *const cm = &cpi->common;
383 MACROBLOCKD *const xd = &cpi->td.mb.e_mbd;
386 xd->mi = cm->mi_grid_visible + (mi_row * cm->mi_stride + mi_col);
389 cpi->td.mb.mbmi_ext = cpi->td.mb.mbmi_ext_base +
390 (mi_row * cm->mi_cols + mi_col);
392 set_mi_row_col(xd, tile,
393 mi_row, num_8x8_blocks_high_lookup[m->mbmi.sb_type],
394 mi_col, num_8x8_blocks_wide_lookup[m->mbmi.sb_type],
395 cm->mi_rows, cm->mi_cols);
396 if (frame_is_intra_only(cm)) {
397 write_mb_modes_kf(cm, xd, xd->mi, w);
399 pack_inter_mode_mvs(cpi, m, w);
402 assert(*tok < tok_end);
403 pack_mb_tokens(w, tok, tok_end, cm->bit_depth);
406 static void write_partition(const VP9_COMMON *const cm,
407 const MACROBLOCKD *const xd,
408 int hbs, int mi_row, int mi_col,
409 PARTITION_TYPE p, BLOCK_SIZE bsize, vpx_writer *w) {
410 const int ctx = partition_plane_context(xd, mi_row, mi_col, bsize);
411 const vpx_prob *const probs = xd->partition_probs[ctx];
412 const int has_rows = (mi_row + hbs) < cm->mi_rows;
413 const int has_cols = (mi_col + hbs) < cm->mi_cols;
415 if (has_rows && has_cols) {
416 vp9_write_token(w, vp9_partition_tree, probs, &partition_encodings[p]);
417 } else if (!has_rows && has_cols) {
418 assert(p == PARTITION_SPLIT || p == PARTITION_HORZ);
419 vpx_write(w, p == PARTITION_SPLIT, probs[1]);
420 } else if (has_rows && !has_cols) {
421 assert(p == PARTITION_SPLIT || p == PARTITION_VERT);
422 vpx_write(w, p == PARTITION_SPLIT, probs[2]);
424 assert(p == PARTITION_SPLIT);
428 static void write_modes_sb(VP9_COMP *cpi,
429 const TileInfo *const tile, vpx_writer *w,
430 TOKENEXTRA **tok, const TOKENEXTRA *const tok_end,
431 int mi_row, int mi_col, BLOCK_SIZE bsize) {
432 const VP9_COMMON *const cm = &cpi->common;
433 MACROBLOCKD *const xd = &cpi->td.mb.e_mbd;
435 const int bsl = b_width_log2_lookup[bsize];
436 const int bs = (1 << bsl) / 4;
437 PARTITION_TYPE partition;
439 const MODE_INFO *m = NULL;
441 if (mi_row >= cm->mi_rows || mi_col >= cm->mi_cols)
444 m = cm->mi_grid_visible[mi_row * cm->mi_stride + mi_col];
446 partition = partition_lookup[bsl][m->mbmi.sb_type];
447 write_partition(cm, xd, bs, mi_row, mi_col, partition, bsize, w);
448 subsize = get_subsize(bsize, partition);
449 if (subsize < BLOCK_8X8) {
450 write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
454 write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
457 write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
458 if (mi_row + bs < cm->mi_rows)
459 write_modes_b(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col);
462 write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
463 if (mi_col + bs < cm->mi_cols)
464 write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col + bs);
466 case PARTITION_SPLIT:
467 write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col, subsize);
468 write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col + bs,
470 write_modes_sb(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col,
472 write_modes_sb(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col + bs,
480 // update partition context
481 if (bsize >= BLOCK_8X8 &&
482 (bsize == BLOCK_8X8 || partition != PARTITION_SPLIT))
483 update_partition_context(xd, mi_row, mi_col, subsize, bsize);
486 static void write_modes(VP9_COMP *cpi,
487 const TileInfo *const tile, vpx_writer *w,
488 TOKENEXTRA **tok, const TOKENEXTRA *const tok_end) {
489 const VP9_COMMON *const cm = &cpi->common;
490 MACROBLOCKD *const xd = &cpi->td.mb.e_mbd;
493 set_partition_probs(cm, xd);
495 for (mi_row = tile->mi_row_start; mi_row < tile->mi_row_end;
496 mi_row += MI_BLOCK_SIZE) {
497 vp9_zero(xd->left_seg_context);
498 for (mi_col = tile->mi_col_start; mi_col < tile->mi_col_end;
499 mi_col += MI_BLOCK_SIZE)
500 write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col,
505 static void build_tree_distribution(VP9_COMP *cpi, TX_SIZE tx_size,
506 vp9_coeff_stats *coef_branch_ct,
507 vp9_coeff_probs_model *coef_probs) {
508 vp9_coeff_count *coef_counts = cpi->td.rd_counts.coef_counts[tx_size];
509 unsigned int (*eob_branch_ct)[REF_TYPES][COEF_BANDS][COEFF_CONTEXTS] =
510 cpi->common.counts.eob_branch[tx_size];
513 for (i = 0; i < PLANE_TYPES; ++i) {
514 for (j = 0; j < REF_TYPES; ++j) {
515 for (k = 0; k < COEF_BANDS; ++k) {
516 for (l = 0; l < BAND_COEFF_CONTEXTS(k); ++l) {
517 vp9_tree_probs_from_distribution(vp9_coef_tree,
518 coef_branch_ct[i][j][k][l],
519 coef_counts[i][j][k][l]);
520 coef_branch_ct[i][j][k][l][0][1] = eob_branch_ct[i][j][k][l] -
521 coef_branch_ct[i][j][k][l][0][0];
522 for (m = 0; m < UNCONSTRAINED_NODES; ++m)
523 coef_probs[i][j][k][l][m] = get_binary_prob(
524 coef_branch_ct[i][j][k][l][m][0],
525 coef_branch_ct[i][j][k][l][m][1]);
532 static void update_coef_probs_common(vpx_writer* const bc, VP9_COMP *cpi,
534 vp9_coeff_stats *frame_branch_ct,
535 vp9_coeff_probs_model *new_coef_probs) {
536 vp9_coeff_probs_model *old_coef_probs = cpi->common.fc->coef_probs[tx_size];
537 const vpx_prob upd = DIFF_UPDATE_PROB;
538 const int entropy_nodes_update = UNCONSTRAINED_NODES;
540 int stepsize = cpi->sf.coeff_prob_appx_step;
542 switch (cpi->sf.use_fast_coef_updates) {
544 /* dry run to see if there is any update at all needed */
546 int update[2] = {0, 0};
547 for (i = 0; i < PLANE_TYPES; ++i) {
548 for (j = 0; j < REF_TYPES; ++j) {
549 for (k = 0; k < COEF_BANDS; ++k) {
550 for (l = 0; l < BAND_COEFF_CONTEXTS(k); ++l) {
551 for (t = 0; t < entropy_nodes_update; ++t) {
552 vpx_prob newp = new_coef_probs[i][j][k][l][t];
553 const vpx_prob oldp = old_coef_probs[i][j][k][l][t];
557 s = vp9_prob_diff_update_savings_search_model(
558 frame_branch_ct[i][j][k][l][0],
559 old_coef_probs[i][j][k][l], &newp, upd, stepsize);
561 s = vp9_prob_diff_update_savings_search(
562 frame_branch_ct[i][j][k][l][t], oldp, &newp, upd);
563 if (s > 0 && newp != oldp)
566 savings += s - (int)(vp9_cost_zero(upd));
568 savings -= (int)(vp9_cost_zero(upd));
576 // printf("Update %d %d, savings %d\n", update[0], update[1], savings);
577 /* Is coef updated at all */
578 if (update[1] == 0 || savings < 0) {
579 vpx_write_bit(bc, 0);
582 vpx_write_bit(bc, 1);
583 for (i = 0; i < PLANE_TYPES; ++i) {
584 for (j = 0; j < REF_TYPES; ++j) {
585 for (k = 0; k < COEF_BANDS; ++k) {
586 for (l = 0; l < BAND_COEFF_CONTEXTS(k); ++l) {
587 // calc probs and branch cts for this frame only
588 for (t = 0; t < entropy_nodes_update; ++t) {
589 vpx_prob newp = new_coef_probs[i][j][k][l][t];
590 vpx_prob *oldp = old_coef_probs[i][j][k][l] + t;
591 const vpx_prob upd = DIFF_UPDATE_PROB;
595 s = vp9_prob_diff_update_savings_search_model(
596 frame_branch_ct[i][j][k][l][0],
597 old_coef_probs[i][j][k][l], &newp, upd, stepsize);
599 s = vp9_prob_diff_update_savings_search(
600 frame_branch_ct[i][j][k][l][t],
602 if (s > 0 && newp != *oldp)
604 vpx_write(bc, u, upd);
606 /* send/use new probability */
607 vp9_write_prob_diff_update(bc, newp, *oldp);
618 case ONE_LOOP_REDUCED: {
620 int noupdates_before_first = 0;
621 for (i = 0; i < PLANE_TYPES; ++i) {
622 for (j = 0; j < REF_TYPES; ++j) {
623 for (k = 0; k < COEF_BANDS; ++k) {
624 for (l = 0; l < BAND_COEFF_CONTEXTS(k); ++l) {
625 // calc probs and branch cts for this frame only
626 for (t = 0; t < entropy_nodes_update; ++t) {
627 vpx_prob newp = new_coef_probs[i][j][k][l][t];
628 vpx_prob *oldp = old_coef_probs[i][j][k][l] + t;
632 if (t == PIVOT_NODE) {
633 s = vp9_prob_diff_update_savings_search_model(
634 frame_branch_ct[i][j][k][l][0],
635 old_coef_probs[i][j][k][l], &newp, upd, stepsize);
637 s = vp9_prob_diff_update_savings_search(
638 frame_branch_ct[i][j][k][l][t],
642 if (s > 0 && newp != *oldp)
645 if (u == 0 && updates == 0) {
646 noupdates_before_first++;
649 if (u == 1 && updates == 1) {
652 vpx_write_bit(bc, 1);
653 for (v = 0; v < noupdates_before_first; ++v)
654 vpx_write(bc, 0, upd);
656 vpx_write(bc, u, upd);
658 /* send/use new probability */
659 vp9_write_prob_diff_update(bc, newp, *oldp);
668 vpx_write_bit(bc, 0); // no updates
677 static void update_coef_probs(VP9_COMP *cpi, vpx_writer* w) {
678 const TX_MODE tx_mode = cpi->common.tx_mode;
679 const TX_SIZE max_tx_size = tx_mode_to_biggest_tx_size[tx_mode];
681 for (tx_size = TX_4X4; tx_size <= max_tx_size; ++tx_size) {
682 vp9_coeff_stats frame_branch_ct[PLANE_TYPES];
683 vp9_coeff_probs_model frame_coef_probs[PLANE_TYPES];
684 if (cpi->td.counts->tx.tx_totals[tx_size] <= 20 ||
685 (tx_size >= TX_16X16 && cpi->sf.tx_size_search_method == USE_TX_8X8)) {
688 build_tree_distribution(cpi, tx_size, frame_branch_ct,
690 update_coef_probs_common(w, cpi, tx_size, frame_branch_ct,
696 static void encode_loopfilter(struct loopfilter *lf,
697 struct vpx_write_bit_buffer *wb) {
700 // Encode the loop filter level and type
701 vpx_wb_write_literal(wb, lf->filter_level, 6);
702 vpx_wb_write_literal(wb, lf->sharpness_level, 3);
704 // Write out loop filter deltas applied at the MB level based on mode or
705 // ref frame (if they are enabled).
706 vpx_wb_write_bit(wb, lf->mode_ref_delta_enabled);
708 if (lf->mode_ref_delta_enabled) {
709 vpx_wb_write_bit(wb, lf->mode_ref_delta_update);
710 if (lf->mode_ref_delta_update) {
711 for (i = 0; i < MAX_REF_LF_DELTAS; i++) {
712 const int delta = lf->ref_deltas[i];
713 const int changed = delta != lf->last_ref_deltas[i];
714 vpx_wb_write_bit(wb, changed);
716 lf->last_ref_deltas[i] = delta;
717 vpx_wb_write_literal(wb, abs(delta) & 0x3F, 6);
718 vpx_wb_write_bit(wb, delta < 0);
722 for (i = 0; i < MAX_MODE_LF_DELTAS; i++) {
723 const int delta = lf->mode_deltas[i];
724 const int changed = delta != lf->last_mode_deltas[i];
725 vpx_wb_write_bit(wb, changed);
727 lf->last_mode_deltas[i] = delta;
728 vpx_wb_write_literal(wb, abs(delta) & 0x3F, 6);
729 vpx_wb_write_bit(wb, delta < 0);
736 static void write_delta_q(struct vpx_write_bit_buffer *wb, int delta_q) {
738 vpx_wb_write_bit(wb, 1);
739 vpx_wb_write_literal(wb, abs(delta_q), 4);
740 vpx_wb_write_bit(wb, delta_q < 0);
742 vpx_wb_write_bit(wb, 0);
746 static void encode_quantization(const VP9_COMMON *const cm,
747 struct vpx_write_bit_buffer *wb) {
748 vpx_wb_write_literal(wb, cm->base_qindex, QINDEX_BITS);
749 write_delta_q(wb, cm->y_dc_delta_q);
750 write_delta_q(wb, cm->uv_dc_delta_q);
751 write_delta_q(wb, cm->uv_ac_delta_q);
754 static void encode_segmentation(VP9_COMMON *cm, MACROBLOCKD *xd,
755 struct vpx_write_bit_buffer *wb) {
758 const struct segmentation *seg = &cm->seg;
760 vpx_wb_write_bit(wb, seg->enabled);
765 vpx_wb_write_bit(wb, seg->update_map);
766 if (seg->update_map) {
767 // Select the coding strategy (temporal or spatial)
768 vp9_choose_segmap_coding_method(cm, xd);
769 // Write out probabilities used to decode unpredicted macro-block segments
770 for (i = 0; i < SEG_TREE_PROBS; i++) {
771 const int prob = seg->tree_probs[i];
772 const int update = prob != MAX_PROB;
773 vpx_wb_write_bit(wb, update);
775 vpx_wb_write_literal(wb, prob, 8);
778 // Write out the chosen coding method.
779 vpx_wb_write_bit(wb, seg->temporal_update);
780 if (seg->temporal_update) {
781 for (i = 0; i < PREDICTION_PROBS; i++) {
782 const int prob = seg->pred_probs[i];
783 const int update = prob != MAX_PROB;
784 vpx_wb_write_bit(wb, update);
786 vpx_wb_write_literal(wb, prob, 8);
792 vpx_wb_write_bit(wb, seg->update_data);
793 if (seg->update_data) {
794 vpx_wb_write_bit(wb, seg->abs_delta);
796 for (i = 0; i < MAX_SEGMENTS; i++) {
797 for (j = 0; j < SEG_LVL_MAX; j++) {
798 const int active = segfeature_active(seg, i, j);
799 vpx_wb_write_bit(wb, active);
801 const int data = get_segdata(seg, i, j);
802 const int data_max = vp9_seg_feature_data_max(j);
804 if (vp9_is_segfeature_signed(j)) {
805 encode_unsigned_max(wb, abs(data), data_max);
806 vpx_wb_write_bit(wb, data < 0);
808 encode_unsigned_max(wb, data, data_max);
816 static void encode_txfm_probs(VP9_COMMON *cm, vpx_writer *w,
817 FRAME_COUNTS *counts) {
819 vpx_write_literal(w, VPXMIN(cm->tx_mode, ALLOW_32X32), 2);
820 if (cm->tx_mode >= ALLOW_32X32)
821 vpx_write_bit(w, cm->tx_mode == TX_MODE_SELECT);
824 if (cm->tx_mode == TX_MODE_SELECT) {
826 unsigned int ct_8x8p[TX_SIZES - 3][2];
827 unsigned int ct_16x16p[TX_SIZES - 2][2];
828 unsigned int ct_32x32p[TX_SIZES - 1][2];
831 for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
832 tx_counts_to_branch_counts_8x8(counts->tx.p8x8[i], ct_8x8p);
833 for (j = 0; j < TX_SIZES - 3; j++)
834 vp9_cond_prob_diff_update(w, &cm->fc->tx_probs.p8x8[i][j], ct_8x8p[j]);
837 for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
838 tx_counts_to_branch_counts_16x16(counts->tx.p16x16[i], ct_16x16p);
839 for (j = 0; j < TX_SIZES - 2; j++)
840 vp9_cond_prob_diff_update(w, &cm->fc->tx_probs.p16x16[i][j],
844 for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
845 tx_counts_to_branch_counts_32x32(counts->tx.p32x32[i], ct_32x32p);
846 for (j = 0; j < TX_SIZES - 1; j++)
847 vp9_cond_prob_diff_update(w, &cm->fc->tx_probs.p32x32[i][j],
853 static void write_interp_filter(INTERP_FILTER filter,
854 struct vpx_write_bit_buffer *wb) {
855 const int filter_to_literal[] = { 1, 0, 2, 3 };
857 vpx_wb_write_bit(wb, filter == SWITCHABLE);
858 if (filter != SWITCHABLE)
859 vpx_wb_write_literal(wb, filter_to_literal[filter], 2);
862 static void fix_interp_filter(VP9_COMMON *cm, FRAME_COUNTS *counts) {
863 if (cm->interp_filter == SWITCHABLE) {
864 // Check to see if only one of the filters is actually used
865 int count[SWITCHABLE_FILTERS];
867 for (i = 0; i < SWITCHABLE_FILTERS; ++i) {
869 for (j = 0; j < SWITCHABLE_FILTER_CONTEXTS; ++j)
870 count[i] += counts->switchable_interp[j][i];
874 // Only one filter is used. So set the filter at frame level
875 for (i = 0; i < SWITCHABLE_FILTERS; ++i) {
877 cm->interp_filter = i;
885 static void write_tile_info(const VP9_COMMON *const cm,
886 struct vpx_write_bit_buffer *wb) {
887 int min_log2_tile_cols, max_log2_tile_cols, ones;
888 vp9_get_tile_n_bits(cm->mi_cols, &min_log2_tile_cols, &max_log2_tile_cols);
891 ones = cm->log2_tile_cols - min_log2_tile_cols;
893 vpx_wb_write_bit(wb, 1);
895 if (cm->log2_tile_cols < max_log2_tile_cols)
896 vpx_wb_write_bit(wb, 0);
899 vpx_wb_write_bit(wb, cm->log2_tile_rows != 0);
900 if (cm->log2_tile_rows != 0)
901 vpx_wb_write_bit(wb, cm->log2_tile_rows != 1);
904 static int get_refresh_mask(VP9_COMP *cpi) {
905 if (vp9_preserve_existing_gf(cpi)) {
906 // We have decided to preserve the previously existing golden frame as our
907 // new ARF frame. However, in the short term we leave it in the GF slot and,
908 // if we're updating the GF with the current decoded frame, we save it
909 // instead to the ARF slot.
910 // Later, in the function vp9_encoder.c:vp9_update_reference_frames() we
911 // will swap gld_fb_idx and alt_fb_idx to achieve our objective. We do it
912 // there so that it can be done outside of the recode loop.
913 // Note: This is highly specific to the use of ARF as a forward reference,
914 // and this needs to be generalized as other uses are implemented
915 // (like RTC/temporal scalability).
916 return (cpi->refresh_last_frame << cpi->lst_fb_idx) |
917 (cpi->refresh_golden_frame << cpi->alt_fb_idx);
919 int arf_idx = cpi->alt_fb_idx;
920 if ((cpi->oxcf.pass == 2) && cpi->multi_arf_allowed) {
921 const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
922 arf_idx = gf_group->arf_update_idx[gf_group->index];
924 return (cpi->refresh_last_frame << cpi->lst_fb_idx) |
925 (cpi->refresh_golden_frame << cpi->gld_fb_idx) |
926 (cpi->refresh_alt_ref_frame << arf_idx);
930 static size_t encode_tiles(VP9_COMP *cpi, uint8_t *data_ptr) {
931 VP9_COMMON *const cm = &cpi->common;
932 vpx_writer residual_bc;
933 int tile_row, tile_col;
935 size_t total_size = 0;
936 const int tile_cols = 1 << cm->log2_tile_cols;
937 const int tile_rows = 1 << cm->log2_tile_rows;
939 memset(cm->above_seg_context, 0,
940 sizeof(*cm->above_seg_context) * mi_cols_aligned_to_sb(cm->mi_cols));
942 for (tile_row = 0; tile_row < tile_rows; tile_row++) {
943 for (tile_col = 0; tile_col < tile_cols; tile_col++) {
944 int tile_idx = tile_row * tile_cols + tile_col;
945 TOKENEXTRA *tok = cpi->tile_tok[tile_row][tile_col];
947 tok_end = cpi->tile_tok[tile_row][tile_col] +
948 cpi->tok_count[tile_row][tile_col];
950 if (tile_col < tile_cols - 1 || tile_row < tile_rows - 1)
951 vpx_start_encode(&residual_bc, data_ptr + total_size + 4);
953 vpx_start_encode(&residual_bc, data_ptr + total_size);
955 write_modes(cpi, &cpi->tile_data[tile_idx].tile_info,
956 &residual_bc, &tok, tok_end);
957 assert(tok == tok_end);
958 vpx_stop_encode(&residual_bc);
959 if (tile_col < tile_cols - 1 || tile_row < tile_rows - 1) {
961 mem_put_be32(data_ptr + total_size, residual_bc.pos);
965 total_size += residual_bc.pos;
972 static void write_display_size(const VP9_COMMON *cm,
973 struct vpx_write_bit_buffer *wb) {
974 const int scaling_active = cm->width != cm->display_width ||
975 cm->height != cm->display_height;
976 vpx_wb_write_bit(wb, scaling_active);
977 if (scaling_active) {
978 vpx_wb_write_literal(wb, cm->display_width - 1, 16);
979 vpx_wb_write_literal(wb, cm->display_height - 1, 16);
983 static void write_frame_size(const VP9_COMMON *cm,
984 struct vpx_write_bit_buffer *wb) {
985 vpx_wb_write_literal(wb, cm->width - 1, 16);
986 vpx_wb_write_literal(wb, cm->height - 1, 16);
988 write_display_size(cm, wb);
991 static void write_frame_size_with_refs(VP9_COMP *cpi,
992 struct vpx_write_bit_buffer *wb) {
993 VP9_COMMON *const cm = &cpi->common;
996 MV_REFERENCE_FRAME ref_frame;
997 for (ref_frame = LAST_FRAME; ref_frame <= ALTREF_FRAME; ++ref_frame) {
998 YV12_BUFFER_CONFIG *cfg = get_ref_frame_buffer(cpi, ref_frame);
1000 // Set "found" to 0 for temporal svc and for spatial svc key frame
1002 ((cpi->svc.number_temporal_layers > 1 &&
1003 cpi->oxcf.rc_mode == VPX_CBR) ||
1004 (cpi->svc.number_spatial_layers > 1 &&
1005 cpi->svc.layer_context[cpi->svc.spatial_layer_id].is_key_frame) ||
1006 (is_two_pass_svc(cpi) &&
1007 cpi->svc.encode_empty_frame_state == ENCODING &&
1008 cpi->svc.layer_context[0].frames_from_key_frame <
1009 cpi->svc.number_temporal_layers + 1))) {
1011 } else if (cfg != NULL) {
1012 found = cm->width == cfg->y_crop_width &&
1013 cm->height == cfg->y_crop_height;
1015 vpx_wb_write_bit(wb, found);
1022 vpx_wb_write_literal(wb, cm->width - 1, 16);
1023 vpx_wb_write_literal(wb, cm->height - 1, 16);
1026 write_display_size(cm, wb);
1029 static void write_sync_code(struct vpx_write_bit_buffer *wb) {
1030 vpx_wb_write_literal(wb, VP9_SYNC_CODE_0, 8);
1031 vpx_wb_write_literal(wb, VP9_SYNC_CODE_1, 8);
1032 vpx_wb_write_literal(wb, VP9_SYNC_CODE_2, 8);
1035 static void write_profile(BITSTREAM_PROFILE profile,
1036 struct vpx_write_bit_buffer *wb) {
1039 vpx_wb_write_literal(wb, 0, 2);
1042 vpx_wb_write_literal(wb, 2, 2);
1045 vpx_wb_write_literal(wb, 1, 2);
1048 vpx_wb_write_literal(wb, 6, 3);
1055 static void write_bitdepth_colorspace_sampling(
1056 VP9_COMMON *const cm, struct vpx_write_bit_buffer *wb) {
1057 if (cm->profile >= PROFILE_2) {
1058 assert(cm->bit_depth > VPX_BITS_8);
1059 vpx_wb_write_bit(wb, cm->bit_depth == VPX_BITS_10 ? 0 : 1);
1061 vpx_wb_write_literal(wb, cm->color_space, 3);
1062 if (cm->color_space != VPX_CS_SRGB) {
1063 vpx_wb_write_bit(wb, 0); // 0: [16, 235] (i.e. xvYCC), 1: [0, 255]
1064 if (cm->profile == PROFILE_1 || cm->profile == PROFILE_3) {
1065 assert(cm->subsampling_x != 1 || cm->subsampling_y != 1);
1066 vpx_wb_write_bit(wb, cm->subsampling_x);
1067 vpx_wb_write_bit(wb, cm->subsampling_y);
1068 vpx_wb_write_bit(wb, 0); // unused
1070 assert(cm->subsampling_x == 1 && cm->subsampling_y == 1);
1073 assert(cm->profile == PROFILE_1 || cm->profile == PROFILE_3);
1074 vpx_wb_write_bit(wb, 0); // unused
1078 static void write_uncompressed_header(VP9_COMP *cpi,
1079 struct vpx_write_bit_buffer *wb) {
1080 VP9_COMMON *const cm = &cpi->common;
1081 MACROBLOCKD *const xd = &cpi->td.mb.e_mbd;
1083 vpx_wb_write_literal(wb, VP9_FRAME_MARKER, 2);
1085 write_profile(cm->profile, wb);
1087 vpx_wb_write_bit(wb, 0); // show_existing_frame
1088 vpx_wb_write_bit(wb, cm->frame_type);
1089 vpx_wb_write_bit(wb, cm->show_frame);
1090 vpx_wb_write_bit(wb, cm->error_resilient_mode);
1092 if (cm->frame_type == KEY_FRAME) {
1093 write_sync_code(wb);
1094 write_bitdepth_colorspace_sampling(cm, wb);
1095 write_frame_size(cm, wb);
1097 // In spatial svc if it's not error_resilient_mode then we need to code all
1098 // visible frames as invisible. But we need to keep the show_frame flag so
1099 // that the publisher could know whether it is supposed to be visible.
1100 // So we will code the show_frame flag as it is. Then code the intra_only
1101 // bit here. This will make the bitstream incompatible. In the player we
1102 // will change to show_frame flag to 0, then add an one byte frame with
1103 // show_existing_frame flag which tells the decoder which frame we want to
1105 if (!cm->show_frame)
1106 vpx_wb_write_bit(wb, cm->intra_only);
1108 if (!cm->error_resilient_mode)
1109 vpx_wb_write_literal(wb, cm->reset_frame_context, 2);
1111 if (cm->intra_only) {
1112 write_sync_code(wb);
1114 // Note for profile 0, 420 8bpp is assumed.
1115 if (cm->profile > PROFILE_0) {
1116 write_bitdepth_colorspace_sampling(cm, wb);
1119 vpx_wb_write_literal(wb, get_refresh_mask(cpi), REF_FRAMES);
1120 write_frame_size(cm, wb);
1122 MV_REFERENCE_FRAME ref_frame;
1123 vpx_wb_write_literal(wb, get_refresh_mask(cpi), REF_FRAMES);
1124 for (ref_frame = LAST_FRAME; ref_frame <= ALTREF_FRAME; ++ref_frame) {
1125 assert(get_ref_frame_map_idx(cpi, ref_frame) != INVALID_IDX);
1126 vpx_wb_write_literal(wb, get_ref_frame_map_idx(cpi, ref_frame),
1128 vpx_wb_write_bit(wb, cm->ref_frame_sign_bias[ref_frame]);
1131 write_frame_size_with_refs(cpi, wb);
1133 vpx_wb_write_bit(wb, cm->allow_high_precision_mv);
1135 fix_interp_filter(cm, cpi->td.counts);
1136 write_interp_filter(cm->interp_filter, wb);
1140 if (!cm->error_resilient_mode) {
1141 vpx_wb_write_bit(wb, cm->refresh_frame_context);
1142 vpx_wb_write_bit(wb, cm->frame_parallel_decoding_mode);
1145 vpx_wb_write_literal(wb, cm->frame_context_idx, FRAME_CONTEXTS_LOG2);
1147 encode_loopfilter(&cm->lf, wb);
1148 encode_quantization(cm, wb);
1149 encode_segmentation(cm, xd, wb);
1151 write_tile_info(cm, wb);
1154 static size_t write_compressed_header(VP9_COMP *cpi, uint8_t *data) {
1155 VP9_COMMON *const cm = &cpi->common;
1156 MACROBLOCKD *const xd = &cpi->td.mb.e_mbd;
1157 FRAME_CONTEXT *const fc = cm->fc;
1158 FRAME_COUNTS *counts = cpi->td.counts;
1159 vpx_writer header_bc;
1161 vpx_start_encode(&header_bc, data);
1164 cm->tx_mode = ONLY_4X4;
1166 encode_txfm_probs(cm, &header_bc, counts);
1168 update_coef_probs(cpi, &header_bc);
1169 update_skip_probs(cm, &header_bc, counts);
1171 if (!frame_is_intra_only(cm)) {
1174 for (i = 0; i < INTER_MODE_CONTEXTS; ++i)
1175 prob_diff_update(vp9_inter_mode_tree, cm->fc->inter_mode_probs[i],
1176 counts->inter_mode[i], INTER_MODES, &header_bc);
1178 if (cm->interp_filter == SWITCHABLE)
1179 update_switchable_interp_probs(cm, &header_bc, counts);
1181 for (i = 0; i < INTRA_INTER_CONTEXTS; i++)
1182 vp9_cond_prob_diff_update(&header_bc, &fc->intra_inter_prob[i],
1183 counts->intra_inter[i]);
1185 if (cpi->allow_comp_inter_inter) {
1186 const int use_compound_pred = cm->reference_mode != SINGLE_REFERENCE;
1187 const int use_hybrid_pred = cm->reference_mode == REFERENCE_MODE_SELECT;
1189 vpx_write_bit(&header_bc, use_compound_pred);
1190 if (use_compound_pred) {
1191 vpx_write_bit(&header_bc, use_hybrid_pred);
1192 if (use_hybrid_pred)
1193 for (i = 0; i < COMP_INTER_CONTEXTS; i++)
1194 vp9_cond_prob_diff_update(&header_bc, &fc->comp_inter_prob[i],
1195 counts->comp_inter[i]);
1199 if (cm->reference_mode != COMPOUND_REFERENCE) {
1200 for (i = 0; i < REF_CONTEXTS; i++) {
1201 vp9_cond_prob_diff_update(&header_bc, &fc->single_ref_prob[i][0],
1202 counts->single_ref[i][0]);
1203 vp9_cond_prob_diff_update(&header_bc, &fc->single_ref_prob[i][1],
1204 counts->single_ref[i][1]);
1208 if (cm->reference_mode != SINGLE_REFERENCE)
1209 for (i = 0; i < REF_CONTEXTS; i++)
1210 vp9_cond_prob_diff_update(&header_bc, &fc->comp_ref_prob[i],
1211 counts->comp_ref[i]);
1213 for (i = 0; i < BLOCK_SIZE_GROUPS; ++i)
1214 prob_diff_update(vp9_intra_mode_tree, cm->fc->y_mode_prob[i],
1215 counts->y_mode[i], INTRA_MODES, &header_bc);
1217 for (i = 0; i < PARTITION_CONTEXTS; ++i)
1218 prob_diff_update(vp9_partition_tree, fc->partition_prob[i],
1219 counts->partition[i], PARTITION_TYPES, &header_bc);
1221 vp9_write_nmv_probs(cm, cm->allow_high_precision_mv, &header_bc,
1225 vpx_stop_encode(&header_bc);
1226 assert(header_bc.pos <= 0xffff);
1228 return header_bc.pos;
1231 void vp9_pack_bitstream(VP9_COMP *cpi, uint8_t *dest, size_t *size) {
1232 uint8_t *data = dest;
1233 size_t first_part_size, uncompressed_hdr_size;
1234 struct vpx_write_bit_buffer wb = {data, 0};
1235 struct vpx_write_bit_buffer saved_wb;
1237 write_uncompressed_header(cpi, &wb);
1239 vpx_wb_write_literal(&wb, 0, 16); // don't know in advance first part. size
1241 uncompressed_hdr_size = vpx_wb_bytes_written(&wb);
1242 data += uncompressed_hdr_size;
1244 vpx_clear_system_state();
1246 first_part_size = write_compressed_header(cpi, data);
1247 data += first_part_size;
1248 // TODO(jbb): Figure out what to do if first_part_size > 16 bits.
1249 vpx_wb_write_literal(&saved_wb, (int)first_part_size, 16);
1251 data += encode_tiles(cpi, data);
1253 *size = data - dest;