The Tor Browser: media/libvpx/vp9/encoder/vp9_bitstream.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_bitstream.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_bitstream.c

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include <assert.h>
 #include <stdio.h>
 #include <limits.h>
 #include "vpx/vpx_encoder.h"
 #include "vpx_mem/vpx_mem.h"
 #include "vp9/common/vp9_entropymode.h"
 #include "vp9/common/vp9_entropymv.h"
 #include "vp9/common/vp9_findnearmv.h"
 #include "vp9/common/vp9_tile_common.h"
 #include "vp9/common/vp9_seg_common.h"
 #include "vp9/common/vp9_pred_common.h"
 #include "vp9/common/vp9_entropy.h"
 #include "vp9/common/vp9_mvref_common.h"
 #include "vp9/common/vp9_treecoder.h"
 #include "vp9/common/vp9_systemdependent.h"
 #include "vp9/common/vp9_pragmas.h"
 #include "vp9/encoder/vp9_mcomp.h"
 #include "vp9/encoder/vp9_encodemv.h"
 #include "vp9/encoder/vp9_bitstream.h"
 #include "vp9/encoder/vp9_segmentation.h"
 #include "vp9/encoder/vp9_subexp.h"
 #include "vp9/encoder/vp9_write_bit_buffer.h"
 #if defined(SECTIONBITS_OUTPUT)
 unsigned __int64 Sectionbits[500];
 #endif
 #ifdef ENTROPY_STATS
 int intra_mode_stats[INTRA_MODES]
                     [INTRA_MODES]
                     [INTRA_MODES];
 vp9_coeff_stats tree_update_hist[TX_SIZES][BLOCK_TYPES];
 extern unsigned int active_section;
 #endif
 #ifdef MODE_STATS
 int64_t tx_count_32x32p_stats[TX_SIZE_CONTEXTS][TX_SIZES];
 int64_t tx_count_16x16p_stats[TX_SIZE_CONTEXTS][TX_SIZES - 1];
 int64_t tx_count_8x8p_stats[TX_SIZE_CONTEXTS][TX_SIZES - 2];
 int64_t switchable_interp_stats[SWITCHABLE_FILTER_CONTEXTS][SWITCHABLE_FILTERS];
 void init_tx_count_stats() {
   vp9_zero(tx_count_32x32p_stats);
   vp9_zero(tx_count_16x16p_stats);
   vp9_zero(tx_count_8x8p_stats);
 }
 void init_switchable_interp_stats() {
   vp9_zero(switchable_interp_stats);
 }
 static void update_tx_count_stats(VP9_COMMON *cm) {
   int i, j;
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     for (j = 0; j < TX_SIZES; j++) {
       tx_count_32x32p_stats[i][j] += cm->fc.tx_count_32x32p[i][j];
     }
   }
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     for (j = 0; j < TX_SIZES - 1; j++) {
       tx_count_16x16p_stats[i][j] += cm->fc.tx_count_16x16p[i][j];
     }
   }
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     for (j = 0; j < TX_SIZES - 2; j++) {
       tx_count_8x8p_stats[i][j] += cm->fc.tx_count_8x8p[i][j];
     }
   }
 }
 static void update_switchable_interp_stats(VP9_COMMON *cm) {
   int i, j;
   for (i = 0; i < SWITCHABLE_FILTER_CONTEXTS; ++i)
     for (j = 0; j < SWITCHABLE_FILTERS; ++j)
       switchable_interp_stats[i][j] += cm->fc.switchable_interp_count[i][j];
 }
 void write_tx_count_stats() {
   int i, j;
   FILE *fp = fopen("tx_count.bin", "wb");
   fwrite(tx_count_32x32p_stats, sizeof(tx_count_32x32p_stats), 1, fp);
   fwrite(tx_count_16x16p_stats, sizeof(tx_count_16x16p_stats), 1, fp);
   fwrite(tx_count_8x8p_stats, sizeof(tx_count_8x8p_stats), 1, fp);
   fclose(fp);
   printf(
       "vp9_default_tx_count_32x32p[TX_SIZE_CONTEXTS][TX_SIZES] = {\n");
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     printf("  { ");
     for (j = 0; j < TX_SIZES; j++) {
       printf("%"PRId64", ", tx_count_32x32p_stats[i][j]);
     }
     printf("},\n");
   }
   printf("};\n");
   printf(
       "vp9_default_tx_count_16x16p[TX_SIZE_CONTEXTS][TX_SIZES-1] = {\n");
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     printf("  { ");
     for (j = 0; j < TX_SIZES - 1; j++) {
       printf("%"PRId64", ", tx_count_16x16p_stats[i][j]);
     }
     printf("},\n");
   }
   printf("};\n");
   printf(
       "vp9_default_tx_count_8x8p[TX_SIZE_CONTEXTS][TX_SIZES-2] = {\n");
   for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
     printf("  { ");
     for (j = 0; j < TX_SIZES - 2; j++) {
       printf("%"PRId64", ", tx_count_8x8p_stats[i][j]);
     }
     printf("},\n");
   }
   printf("};\n");
 }
 void write_switchable_interp_stats() {
   int i, j;
   FILE *fp = fopen("switchable_interp.bin", "wb");
   fwrite(switchable_interp_stats, sizeof(switchable_interp_stats), 1, fp);
   fclose(fp);
   printf(
       "vp9_default_switchable_filter_count[SWITCHABLE_FILTER_CONTEXTS]"
       "[SWITCHABLE_FILTERS] = {\n");
   for (i = 0; i < SWITCHABLE_FILTER_CONTEXTS; i++) {
     printf("  { ");
     for (j = 0; j < SWITCHABLE_FILTERS; j++) {
       printf("%"PRId64", ", switchable_interp_stats[i][j]);
     }
     printf("},\n");
   }
   printf("};\n");
 }
 #endif
 static INLINE void write_be32(uint8_t *p, int value) {
   p[0] = value >> 24;
   p[1] = value >> 16;
   p[2] = value >> 8;
   p[3] = value;
 }
 void vp9_encode_unsigned_max(struct vp9_write_bit_buffer *wb,
                              int data, int max) {
   vp9_wb_write_literal(wb, data, get_unsigned_bits(max));
 }
 static void update_mode(vp9_writer *w, int n, vp9_tree tree,
                         vp9_prob Pcur[/* n-1 */],
                         unsigned int bct[/* n-1 */][2],
                         const unsigned int num_events[/* n */]) {
   int i = 0;
   vp9_tree_probs_from_distribution(tree, bct, num_events);
   for (i = 0; i < n - 1; ++i)
     vp9_cond_prob_diff_update(w, &Pcur[i], bct[i]);
 }
 static void update_mbintra_mode_probs(VP9_COMP* const cpi,
                                       vp9_writer* const bc) {
   VP9_COMMON *const cm = &cpi->common;
   int j;
   unsigned int bct[INTRA_MODES - 1][2];
   for (j = 0; j < BLOCK_SIZE_GROUPS; j++)
     update_mode(bc, INTRA_MODES, vp9_intra_mode_tree,
                 cm->fc.y_mode_prob[j], bct,
                 (unsigned int *)cpi->y_mode_count[j]);
 }
 static void write_selected_tx_size(const VP9_COMP *cpi, MODE_INFO *m,
                                    TX_SIZE tx_size, BLOCK_SIZE bsize,
                                    vp9_writer *w) {
   const TX_SIZE max_tx_size = max_txsize_lookup[bsize];
   const MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   const vp9_prob *const tx_probs = get_tx_probs2(max_tx_size, xd,
                                                  &cpi->common.fc.tx_probs);
   vp9_write(w, tx_size != TX_4X4, tx_probs[0]);
   if (tx_size != TX_4X4 && max_tx_size >= TX_16X16) {
     vp9_write(w, tx_size != TX_8X8, tx_probs[1]);
     if (tx_size != TX_8X8 && max_tx_size >= TX_32X32)
       vp9_write(w, tx_size != TX_16X16, tx_probs[2]);
   }
 }
 static int write_skip_coeff(const VP9_COMP *cpi, int segment_id, MODE_INFO *m,
                             vp9_writer *w) {
   const MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   if (vp9_segfeature_active(&cpi->common.seg, segment_id, SEG_LVL_SKIP)) {
     return 1;
   } else {
     const int skip_coeff = m->mbmi.skip_coeff;
     vp9_write(w, skip_coeff, vp9_get_pred_prob_mbskip(&cpi->common, xd));
     return skip_coeff;
   }
 }
 void vp9_update_skip_probs(VP9_COMP *cpi, vp9_writer *w) {
   VP9_COMMON *cm = &cpi->common;
   int k;
   for (k = 0; k < MBSKIP_CONTEXTS; ++k)
     vp9_cond_prob_diff_update(w, &cm->fc.mbskip_probs[k], cm->counts.mbskip[k]);
 }
 static void write_intra_mode(vp9_writer *bc, int m, const vp9_prob *p) {
   write_token(bc, vp9_intra_mode_tree, p, vp9_intra_mode_encodings + m);
 }
 static void update_switchable_interp_probs(VP9_COMP *cpi, vp9_writer *w) {
   VP9_COMMON *const cm = &cpi->common;
   unsigned int branch_ct[SWITCHABLE_FILTERS - 1][2];
   int i, j;
   for (j = 0; j < SWITCHABLE_FILTER_CONTEXTS; ++j) {
     vp9_tree_probs_from_distribution(vp9_switchable_interp_tree, branch_ct,
                                      cm->counts.switchable_interp[j]);
     for (i = 0; i < SWITCHABLE_FILTERS - 1; ++i)
       vp9_cond_prob_diff_update(w, &cm->fc.switchable_interp_prob[j][i],
                                 branch_ct[i]);
   }
 #ifdef MODE_STATS
   if (!cpi->dummy_packing)
     update_switchable_interp_stats(cm);
 #endif
 }
 static void update_inter_mode_probs(VP9_COMMON *cm, vp9_writer *w) {
   int i, j;
   for (i = 0; i < INTER_MODE_CONTEXTS; ++i) {
     unsigned int branch_ct[INTER_MODES - 1][2];
     vp9_tree_probs_from_distribution(vp9_inter_mode_tree, branch_ct,
                                      cm->counts.inter_mode[i]);
     for (j = 0; j < INTER_MODES - 1; ++j)
       vp9_cond_prob_diff_update(w, &cm->fc.inter_mode_probs[i][j],
                                 branch_ct[j]);
   }
 }
 static void pack_mb_tokens(vp9_writer* const w,
                            TOKENEXTRA **tp,
                            const TOKENEXTRA *const stop) {
   TOKENEXTRA *p = *tp;
   while (p < stop && p->token != EOSB_TOKEN) {
     const int t = p->token;
     const struct vp9_token *const a = &vp9_coef_encodings[t];
     const vp9_extra_bit *const b = &vp9_extra_bits[t];
     int i = 0;
     const vp9_prob *pp;
     int v = a->value;
     int n = a->len;
     vp9_prob probs[ENTROPY_NODES];
     if (t >= TWO_TOKEN) {
       vp9_model_to_full_probs(p->context_tree, probs);
       pp = probs;
     } else {
       pp = p->context_tree;
     }
     assert(pp != 0);
     /* skip one or two nodes */
     if (p->skip_eob_node) {
       n -= p->skip_eob_node;
       i = 2 * p->skip_eob_node;
     }
     do {
       const int bb = (v >> --n) & 1;
       vp9_write(w, bb, pp[i >> 1]);
       i = vp9_coef_tree[i + bb];
     } while (n);
     if (b->base_val) {
       const int e = p->extra, l = b->len;
       if (l) {
         const unsigned char *pb = b->prob;
         int v = e >> 1;
         int n = l;              /* number of bits in v, assumed nonzero */
         int i = 0;
         do {
           const int bb = (v >> --n) & 1;
           vp9_write(w, bb, pb[i >> 1]);
           i = b->tree[i + bb];
         } while (n);
       }
       vp9_write_bit(w, e & 1);
     }
     ++p;
   }
   *tp = p + (p->token == EOSB_TOKEN);
 }
 static void write_sb_mv_ref(vp9_writer *w, MB_PREDICTION_MODE mode,
                             const vp9_prob *p) {
   assert(is_inter_mode(mode));
   write_token(w, vp9_inter_mode_tree, p,
               &vp9_inter_mode_encodings[INTER_OFFSET(mode)]);
 }
 static void write_segment_id(vp9_writer *w, const struct segmentation *seg,
                              int segment_id) {
   if (seg->enabled && seg->update_map)
     treed_write(w, vp9_segment_tree, seg->tree_probs, segment_id, 3);
 }
 // This function encodes the reference frame
 static void encode_ref_frame(VP9_COMP *cpi, vp9_writer *bc) {
   VP9_COMMON *const cm = &cpi->common;
   MACROBLOCK *const x = &cpi->mb;
   MACROBLOCKD *const xd = &x->e_mbd;
   MB_MODE_INFO *mi = &xd->mi_8x8[0]->mbmi;
   const int segment_id = mi->segment_id;
   int seg_ref_active = vp9_segfeature_active(&cm->seg, segment_id,
                                              SEG_LVL_REF_FRAME);
   // If segment level coding of this signal is disabled...
   // or the segment allows multiple reference frame options
   if (!seg_ref_active) {
     // does the feature use compound prediction or not
     // (if not specified at the frame/segment level)
     if (cm->comp_pred_mode == HYBRID_PREDICTION) {
       vp9_write(bc, mi->ref_frame[1] > INTRA_FRAME,
                 vp9_get_pred_prob_comp_inter_inter(cm, xd));
     } else {
       assert((mi->ref_frame[1] <= INTRA_FRAME) ==
                  (cm->comp_pred_mode == SINGLE_PREDICTION_ONLY));
     }
     if (mi->ref_frame[1] > INTRA_FRAME) {
       vp9_write(bc, mi->ref_frame[0] == GOLDEN_FRAME,
                 vp9_get_pred_prob_comp_ref_p(cm, xd));
     } else {
       vp9_write(bc, mi->ref_frame[0] != LAST_FRAME,
                 vp9_get_pred_prob_single_ref_p1(cm, xd));
       if (mi->ref_frame[0] != LAST_FRAME)
         vp9_write(bc, mi->ref_frame[0] != GOLDEN_FRAME,
                   vp9_get_pred_prob_single_ref_p2(cm, xd));
     }
   } else {
     assert(mi->ref_frame[1] <= INTRA_FRAME);
     assert(vp9_get_segdata(&cm->seg, segment_id, SEG_LVL_REF_FRAME) ==
            mi->ref_frame[0]);
   }
   // If using the prediction model we have nothing further to do because
   // the reference frame is fully coded by the segment.
 }
 static void pack_inter_mode_mvs(VP9_COMP *cpi, MODE_INFO *m, vp9_writer *bc) {
   VP9_COMMON *const cm = &cpi->common;
   const nmv_context *nmvc = &cm->fc.nmvc;
   MACROBLOCK *const x = &cpi->mb;
   MACROBLOCKD *const xd = &x->e_mbd;
   struct segmentation *seg = &cm->seg;
   MB_MODE_INFO *const mi = &m->mbmi;
   const MV_REFERENCE_FRAME rf = mi->ref_frame[0];
   const MB_PREDICTION_MODE mode = mi->mode;
   const int segment_id = mi->segment_id;
   int skip_coeff;
   const BLOCK_SIZE bsize = mi->sb_type;
   const int allow_hp = cm->allow_high_precision_mv;
 #ifdef ENTROPY_STATS
   active_section = 9;
 #endif
   if (seg->update_map) {
     if (seg->temporal_update) {
       const int pred_flag = mi->seg_id_predicted;
       vp9_prob pred_prob = vp9_get_pred_prob_seg_id(seg, xd);
       vp9_write(bc, pred_flag, pred_prob);
       if (!pred_flag)
         write_segment_id(bc, seg, segment_id);
     } else {
       write_segment_id(bc, seg, segment_id);
     }
   }
   skip_coeff = write_skip_coeff(cpi, segment_id, m, bc);
   if (!vp9_segfeature_active(seg, segment_id, SEG_LVL_REF_FRAME))
     vp9_write(bc, rf != INTRA_FRAME,
               vp9_get_pred_prob_intra_inter(cm, xd));
   if (bsize >= BLOCK_8X8 && cm->tx_mode == TX_MODE_SELECT &&
       !(rf != INTRA_FRAME &&
         (skip_coeff || vp9_segfeature_active(seg, segment_id, SEG_LVL_SKIP)))) {
     write_selected_tx_size(cpi, m, mi->tx_size, bsize, bc);
   }
   if (rf == INTRA_FRAME) {
 #ifdef ENTROPY_STATS
     active_section = 6;
 #endif
     if (bsize >= BLOCK_8X8) {
       write_intra_mode(bc, mode, cm->fc.y_mode_prob[size_group_lookup[bsize]]);
     } else {
       int idx, idy;
       const int num_4x4_blocks_wide = num_4x4_blocks_wide_lookup[bsize];
       const int num_4x4_blocks_high = num_4x4_blocks_high_lookup[bsize];
       for (idy = 0; idy < 2; idy += num_4x4_blocks_high) {
         for (idx = 0; idx < 2; idx += num_4x4_blocks_wide) {
           const MB_PREDICTION_MODE bm = m->bmi[idy * 2 + idx].as_mode;
           write_intra_mode(bc, bm, cm->fc.y_mode_prob[0]);
         }
       }
     }
     write_intra_mode(bc, mi->uv_mode, cm->fc.uv_mode_prob[mode]);
   } else {
     vp9_prob *mv_ref_p;
     encode_ref_frame(cpi, bc);
     mv_ref_p = cpi->common.fc.inter_mode_probs[mi->mode_context[rf]];
 #ifdef ENTROPY_STATS
     active_section = 3;
 #endif
     // If segment skip is not enabled code the mode.
     if (!vp9_segfeature_active(seg, segment_id, SEG_LVL_SKIP)) {
       if (bsize >= BLOCK_8X8) {
         write_sb_mv_ref(bc, mode, mv_ref_p);
         ++cm->counts.inter_mode[mi->mode_context[rf]]
                                [INTER_OFFSET(mode)];
       }
     }
     if (cm->mcomp_filter_type == SWITCHABLE) {
       const int ctx = vp9_get_pred_context_switchable_interp(xd);
       write_token(bc, vp9_switchable_interp_tree,
                   cm->fc.switchable_interp_prob[ctx],
                   &vp9_switchable_interp_encodings[mi->interp_filter]);
     } else {
       assert(mi->interp_filter == cm->mcomp_filter_type);
     }
     if (bsize < BLOCK_8X8) {
       const int num_4x4_blocks_wide = num_4x4_blocks_wide_lookup[bsize];
       const int num_4x4_blocks_high = num_4x4_blocks_high_lookup[bsize];
       int idx, idy;
       for (idy = 0; idy < 2; idy += num_4x4_blocks_high) {
         for (idx = 0; idx < 2; idx += num_4x4_blocks_wide) {
           const int j = idy * 2 + idx;
           const MB_PREDICTION_MODE blockmode = m->bmi[j].as_mode;
           write_sb_mv_ref(bc, blockmode, mv_ref_p);
           ++cm->counts.inter_mode[mi->mode_context[rf]]
                                  [INTER_OFFSET(blockmode)];
           if (blockmode == NEWMV) {
 #ifdef ENTROPY_STATS
             active_section = 11;
 #endif
             vp9_encode_mv(cpi, bc, &m->bmi[j].as_mv[0].as_mv,
                           &mi->best_mv[0].as_mv, nmvc, allow_hp);
             if (has_second_ref(mi))
               vp9_encode_mv(cpi, bc, &m->bmi[j].as_mv[1].as_mv,
                             &mi->best_mv[1].as_mv, nmvc, allow_hp);
           }
         }
       }
     } else if (mode == NEWMV) {
 #ifdef ENTROPY_STATS
       active_section = 5;
 #endif
       vp9_encode_mv(cpi, bc, &mi->mv[0].as_mv,
                     &mi->best_mv[0].as_mv, nmvc, allow_hp);
       if (has_second_ref(mi))
         vp9_encode_mv(cpi, bc, &mi->mv[1].as_mv,
                       &mi->best_mv[1].as_mv, nmvc, allow_hp);
     }
   }
 }
 static void write_mb_modes_kf(const VP9_COMP *cpi, MODE_INFO **mi_8x8,
                               vp9_writer *bc) {
   const VP9_COMMON *const cm = &cpi->common;
   const MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   const struct segmentation *const seg = &cm->seg;
   MODE_INFO *m = mi_8x8[0];
   const int ym = m->mbmi.mode;
   const int segment_id = m->mbmi.segment_id;
   MODE_INFO *above_mi = mi_8x8[-xd->mode_info_stride];
   MODE_INFO *left_mi = xd->left_available ? mi_8x8[-1] : NULL;
   if (seg->update_map)
     write_segment_id(bc, seg, m->mbmi.segment_id);
   write_skip_coeff(cpi, segment_id, m, bc);
   if (m->mbmi.sb_type >= BLOCK_8X8 && cm->tx_mode == TX_MODE_SELECT)
     write_selected_tx_size(cpi, m, m->mbmi.tx_size, m->mbmi.sb_type, bc);
   if (m->mbmi.sb_type >= BLOCK_8X8) {
     const MB_PREDICTION_MODE A = above_block_mode(m, above_mi, 0);
     const MB_PREDICTION_MODE L = left_block_mode(m, left_mi, 0);
     write_intra_mode(bc, ym, vp9_kf_y_mode_prob[A][L]);
   } else {
     int idx, idy;
     const int num_4x4_blocks_wide = num_4x4_blocks_wide_lookup[m->mbmi.sb_type];
     const int num_4x4_blocks_high = num_4x4_blocks_high_lookup[m->mbmi.sb_type];
     for (idy = 0; idy < 2; idy += num_4x4_blocks_high) {
       for (idx = 0; idx < 2; idx += num_4x4_blocks_wide) {
         int i = idy * 2 + idx;
         const MB_PREDICTION_MODE A = above_block_mode(m, above_mi, i);
         const MB_PREDICTION_MODE L = left_block_mode(m, left_mi, i);
         const int bm = m->bmi[i].as_mode;
 #ifdef ENTROPY_STATS
         ++intra_mode_stats[A][L][bm];
 #endif
         write_intra_mode(bc, bm, vp9_kf_y_mode_prob[A][L]);
       }
     }
   }
   write_intra_mode(bc, m->mbmi.uv_mode, vp9_kf_uv_mode_prob[ym]);
 }
 static void write_modes_b(VP9_COMP *cpi, const TileInfo *const tile,
                           vp9_writer *w, TOKENEXTRA **tok, TOKENEXTRA *tok_end,
                           int mi_row, int mi_col) {
   VP9_COMMON *const cm = &cpi->common;
   MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   MODE_INFO *m;
   xd->mi_8x8 = cm->mi_grid_visible + (mi_row * cm->mode_info_stride + mi_col);
   m = xd->mi_8x8[0];
   set_mi_row_col(xd, tile,
                  mi_row, num_8x8_blocks_high_lookup[m->mbmi.sb_type],
                  mi_col, num_8x8_blocks_wide_lookup[m->mbmi.sb_type],
                  cm->mi_rows, cm->mi_cols);
   if (frame_is_intra_only(cm)) {
     write_mb_modes_kf(cpi, xd->mi_8x8, w);
 #ifdef ENTROPY_STATS
     active_section = 8;
 #endif
   } else {
     pack_inter_mode_mvs(cpi, m, w);
 #ifdef ENTROPY_STATS
     active_section = 1;
 #endif
   }
   assert(*tok < tok_end);
   pack_mb_tokens(w, tok, tok_end);
 }
 static void write_partition(VP9_COMP *cpi, int hbs, int mi_row, int mi_col,
                             PARTITION_TYPE p, BLOCK_SIZE bsize, vp9_writer *w) {
   VP9_COMMON *const cm = &cpi->common;
   const int ctx = partition_plane_context(cpi->above_seg_context,
                                           cpi->left_seg_context,
                                           mi_row, mi_col, bsize);
   const vp9_prob *const probs = get_partition_probs(cm, ctx);
   const int has_rows = (mi_row + hbs) < cm->mi_rows;
   const int has_cols = (mi_col + hbs) < cm->mi_cols;
   if (has_rows && has_cols) {
     write_token(w, vp9_partition_tree, probs, &vp9_partition_encodings[p]);
   } else if (!has_rows && has_cols) {
     assert(p == PARTITION_SPLIT || p == PARTITION_HORZ);
     vp9_write(w, p == PARTITION_SPLIT, probs[1]);
   } else if (has_rows && !has_cols) {
     assert(p == PARTITION_SPLIT || p == PARTITION_VERT);
     vp9_write(w, p == PARTITION_SPLIT, probs[2]);
   } else {
     assert(p == PARTITION_SPLIT);
   }
 }
 static void write_modes_sb(VP9_COMP *cpi, const TileInfo *const tile,
                            vp9_writer *w, TOKENEXTRA **tok, TOKENEXTRA *tok_end,
                            int mi_row, int mi_col, BLOCK_SIZE bsize) {
   VP9_COMMON *const cm = &cpi->common;
   const int bsl = b_width_log2(bsize);
   const int bs = (1 << bsl) / 4;
   PARTITION_TYPE partition;
   BLOCK_SIZE subsize;
   MODE_INFO *m = cm->mi_grid_visible[mi_row * cm->mode_info_stride + mi_col];
   if (mi_row >= cm->mi_rows || mi_col >= cm->mi_cols)
     return;
   partition = partition_lookup[bsl][m->mbmi.sb_type];
   write_partition(cpi, bs, mi_row, mi_col, partition, bsize, w);
   subsize = get_subsize(bsize, partition);
   if (subsize < BLOCK_8X8) {
     write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
   } else {
     switch (partition) {
       case PARTITION_NONE:
         write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
         break;
       case PARTITION_HORZ:
         write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
         if (mi_row + bs < cm->mi_rows)
           write_modes_b(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col);
         break;
       case PARTITION_VERT:
         write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col);
         if (mi_col + bs < cm->mi_cols)
           write_modes_b(cpi, tile, w, tok, tok_end, mi_row, mi_col + bs);
         break;
       case PARTITION_SPLIT:
         write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col, subsize);
         write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col + bs,
                        subsize);
         write_modes_sb(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col,
                        subsize);
         write_modes_sb(cpi, tile, w, tok, tok_end, mi_row + bs, mi_col + bs,
                        subsize);
         break;
       default:
         assert(0);
     }
   }
   // update partition context
   if (bsize >= BLOCK_8X8 &&
       (bsize == BLOCK_8X8 || partition != PARTITION_SPLIT))
     update_partition_context(cpi->above_seg_context, cpi->left_seg_context,
                              mi_row, mi_col, subsize, bsize);
 }
 static void write_modes(VP9_COMP *cpi, const TileInfo *const tile,
                         vp9_writer *w, TOKENEXTRA **tok, TOKENEXTRA *tok_end) {
   int mi_row, mi_col;
   for (mi_row = tile->mi_row_start; mi_row < tile->mi_row_end;
        mi_row += MI_BLOCK_SIZE) {
       vp9_zero(cpi->left_seg_context);
     for (mi_col = tile->mi_col_start; mi_col < tile->mi_col_end;
          mi_col += MI_BLOCK_SIZE)
       write_modes_sb(cpi, tile, w, tok, tok_end, mi_row, mi_col, BLOCK_64X64);
   }
 }
 static void build_tree_distribution(VP9_COMP *cpi, TX_SIZE tx_size) {
   vp9_coeff_probs_model *coef_probs = cpi->frame_coef_probs[tx_size];
   vp9_coeff_count *coef_counts = cpi->coef_counts[tx_size];
   unsigned int (*eob_branch_ct)[REF_TYPES][COEF_BANDS][PREV_COEF_CONTEXTS] =
       cpi->common.counts.eob_branch[tx_size];
   vp9_coeff_stats *coef_branch_ct = cpi->frame_branch_ct[tx_size];
   int i, j, k, l, m;
   for (i = 0; i < BLOCK_TYPES; ++i) {
     for (j = 0; j < REF_TYPES; ++j) {
       for (k = 0; k < COEF_BANDS; ++k) {
         for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
           if (l >= 3 && k == 0)
             continue;
           vp9_tree_probs_from_distribution(vp9_coef_tree,
                                            coef_branch_ct[i][j][k][l],
                                            coef_counts[i][j][k][l]);
           coef_branch_ct[i][j][k][l][0][1] = eob_branch_ct[i][j][k][l] -
                                              coef_branch_ct[i][j][k][l][0][0];
           for (m = 0; m < UNCONSTRAINED_NODES; ++m)
             coef_probs[i][j][k][l][m] = get_binary_prob(
                                             coef_branch_ct[i][j][k][l][m][0],
                                             coef_branch_ct[i][j][k][l][m][1]);
 #ifdef ENTROPY_STATS
           if (!cpi->dummy_packing) {
             int t;
             for (t = 0; t < MAX_ENTROPY_TOKENS; ++t)
               context_counters[tx_size][i][j][k][l][t] +=
                   coef_counts[i][j][k][l][t];
             context_counters[tx_size][i][j][k][l][MAX_ENTROPY_TOKENS] +=
                 eob_branch_ct[i][j][k][l];
           }
 #endif
         }
       }
     }
   }
 }
 static void build_coeff_contexts(VP9_COMP *cpi) {
   TX_SIZE t;
   for (t = TX_4X4; t <= TX_32X32; t++)
     build_tree_distribution(cpi, t);
 }
 static void update_coef_probs_common(vp9_writer* const bc, VP9_COMP *cpi,
                                      TX_SIZE tx_size) {
   vp9_coeff_probs_model *new_frame_coef_probs = cpi->frame_coef_probs[tx_size];
   vp9_coeff_probs_model *old_frame_coef_probs =
       cpi->common.fc.coef_probs[tx_size];
   vp9_coeff_stats *frame_branch_ct = cpi->frame_branch_ct[tx_size];
   const vp9_prob upd = DIFF_UPDATE_PROB;
   const int entropy_nodes_update = UNCONSTRAINED_NODES;
   int i, j, k, l, t;
   switch (cpi->sf.use_fast_coef_updates) {
     case 0: {
       /* dry run to see if there is any udpate at all needed */
       int savings = 0;
       int update[2] = {0, 0};
       for (i = 0; i < BLOCK_TYPES; ++i) {
         for (j = 0; j < REF_TYPES; ++j) {
           for (k = 0; k < COEF_BANDS; ++k) {
             for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
               for (t = 0; t < entropy_nodes_update; ++t) {
                 vp9_prob newp = new_frame_coef_probs[i][j][k][l][t];
                 const vp9_prob oldp = old_frame_coef_probs[i][j][k][l][t];
                 int s;
                 int u = 0;
                 if (l >= 3 && k == 0)
                   continue;
                 if (t == PIVOT_NODE)
                   s = vp9_prob_diff_update_savings_search_model(
                       frame_branch_ct[i][j][k][l][0],
                       old_frame_coef_probs[i][j][k][l], &newp, upd, i, j);
                 else
                   s = vp9_prob_diff_update_savings_search(
                       frame_branch_ct[i][j][k][l][t], oldp, &newp, upd);
                 if (s > 0 && newp != oldp)
                   u = 1;
                 if (u)
                   savings += s - (int)(vp9_cost_zero(upd));
                 else
                   savings -= (int)(vp9_cost_zero(upd));
                 update[u]++;
               }
             }
           }
         }
       }
       // printf("Update %d %d, savings %d\n", update[0], update[1], savings);
       /* Is coef updated at all */
       if (update[1] == 0 || savings < 0) {
         vp9_write_bit(bc, 0);
         return;
       }
       vp9_write_bit(bc, 1);
       for (i = 0; i < BLOCK_TYPES; ++i) {
         for (j = 0; j < REF_TYPES; ++j) {
           for (k = 0; k < COEF_BANDS; ++k) {
             for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
               // calc probs and branch cts for this frame only
               for (t = 0; t < entropy_nodes_update; ++t) {
                 vp9_prob newp = new_frame_coef_probs[i][j][k][l][t];
                 vp9_prob *oldp = old_frame_coef_probs[i][j][k][l] + t;
                 const vp9_prob upd = DIFF_UPDATE_PROB;
                 int s;
                 int u = 0;
                 if (l >= 3 && k == 0)
                   continue;
                 if (t == PIVOT_NODE)
                   s = vp9_prob_diff_update_savings_search_model(
                       frame_branch_ct[i][j][k][l][0],
                       old_frame_coef_probs[i][j][k][l], &newp, upd, i, j);
                 else
                   s = vp9_prob_diff_update_savings_search(
                       frame_branch_ct[i][j][k][l][t],
                       *oldp, &newp, upd);
                 if (s > 0 && newp != *oldp)
                   u = 1;
                 vp9_write(bc, u, upd);
 #ifdef ENTROPY_STATS
                 if (!cpi->dummy_packing)
                   ++tree_update_hist[tx_size][i][j][k][l][t][u];
 #endif
                 if (u) {
                   /* send/use new probability */
                   vp9_write_prob_diff_update(bc, newp, *oldp);
                   *oldp = newp;
                 }
               }
             }
           }
         }
       }
       return;
     }
     case 1:
     case 2: {
       const int prev_coef_contexts_to_update =
           (cpi->sf.use_fast_coef_updates == 2 ?
            PREV_COEF_CONTEXTS >> 1 : PREV_COEF_CONTEXTS);
       const int coef_band_to_update =
           (cpi->sf.use_fast_coef_updates == 2 ?
            COEF_BANDS >> 1 : COEF_BANDS);
       int updates = 0;
       int noupdates_before_first = 0;
       for (i = 0; i < BLOCK_TYPES; ++i) {
         for (j = 0; j < REF_TYPES; ++j) {
           for (k = 0; k < COEF_BANDS; ++k) {
             for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
               // calc probs and branch cts for this frame only
               for (t = 0; t < entropy_nodes_update; ++t) {
                 vp9_prob newp = new_frame_coef_probs[i][j][k][l][t];
                 vp9_prob *oldp = old_frame_coef_probs[i][j][k][l] + t;
                 int s;
                 int u = 0;
                 if (l >= 3 && k == 0)
                   continue;
                 if (l >= prev_coef_contexts_to_update ||
                     k >= coef_band_to_update) {
                   u = 0;
                 } else {
                   if (t == PIVOT_NODE)
                     s = vp9_prob_diff_update_savings_search_model(
                         frame_branch_ct[i][j][k][l][0],
                         old_frame_coef_probs[i][j][k][l], &newp, upd, i, j);
                   else
                     s = vp9_prob_diff_update_savings_search(
                         frame_branch_ct[i][j][k][l][t],
                         *oldp, &newp, upd);
                   if (s > 0 && newp != *oldp)
                     u = 1;
                 }
                 updates += u;
                 if (u == 0 && updates == 0) {
                   noupdates_before_first++;
 #ifdef ENTROPY_STATS
                   if (!cpi->dummy_packing)
                     ++tree_update_hist[tx_size][i][j][k][l][t][u];
 #endif
                   continue;
                 }
                 if (u == 1 && updates == 1) {
                   int v;
                   // first update
                   vp9_write_bit(bc, 1);
                   for (v = 0; v < noupdates_before_first; ++v)
                     vp9_write(bc, 0, upd);
                 }
                 vp9_write(bc, u, upd);
 #ifdef ENTROPY_STATS
                 if (!cpi->dummy_packing)
                   ++tree_update_hist[tx_size][i][j][k][l][t][u];
 #endif
                 if (u) {
                   /* send/use new probability */
                   vp9_write_prob_diff_update(bc, newp, *oldp);
                   *oldp = newp;
                 }
               }
             }
           }
         }
       }
       if (updates == 0) {
         vp9_write_bit(bc, 0);  // no updates
       }
       return;
     }
     default:
       assert(0);
   }
 }
 static void update_coef_probs(VP9_COMP* const cpi, vp9_writer* const bc) {
   const TX_MODE tx_mode = cpi->common.tx_mode;
   vp9_clear_system_state();
   // Build the cofficient contexts based on counts collected in encode loop
   build_coeff_contexts(cpi);
   update_coef_probs_common(bc, cpi, TX_4X4);
   // do not do this if not even allowed
   if (tx_mode > ONLY_4X4)
     update_coef_probs_common(bc, cpi, TX_8X8);
   if (tx_mode > ALLOW_8X8)
     update_coef_probs_common(bc, cpi, TX_16X16);
   if (tx_mode > ALLOW_16X16)
     update_coef_probs_common(bc, cpi, TX_32X32);
 }
 static void encode_loopfilter(struct loopfilter *lf,
                               struct vp9_write_bit_buffer *wb) {
   int i;
   // Encode the loop filter level and type
   vp9_wb_write_literal(wb, lf->filter_level, 6);
   vp9_wb_write_literal(wb, lf->sharpness_level, 3);
   // Write out loop filter deltas applied at the MB level based on mode or
   // ref frame (if they are enabled).
   vp9_wb_write_bit(wb, lf->mode_ref_delta_enabled);
   if (lf->mode_ref_delta_enabled) {
     // Do the deltas need to be updated
     vp9_wb_write_bit(wb, lf->mode_ref_delta_update);
     if (lf->mode_ref_delta_update) {
       // Send update
       for (i = 0; i < MAX_REF_LF_DELTAS; i++) {
         const int delta = lf->ref_deltas[i];
         // Frame level data
         if (delta != lf->last_ref_deltas[i]) {
           lf->last_ref_deltas[i] = delta;
           vp9_wb_write_bit(wb, 1);
           assert(delta != 0);
           vp9_wb_write_literal(wb, abs(delta) & 0x3F, 6);
           vp9_wb_write_bit(wb, delta < 0);
         } else {
           vp9_wb_write_bit(wb, 0);
         }
       }
       // Send update
       for (i = 0; i < MAX_MODE_LF_DELTAS; i++) {
         const int delta = lf->mode_deltas[i];
         if (delta != lf->last_mode_deltas[i]) {
           lf->last_mode_deltas[i] = delta;
           vp9_wb_write_bit(wb, 1);
           assert(delta != 0);
           vp9_wb_write_literal(wb, abs(delta) & 0x3F, 6);
           vp9_wb_write_bit(wb, delta < 0);
         } else {
           vp9_wb_write_bit(wb, 0);
         }
       }
     }
   }
 }
 static void write_delta_q(struct vp9_write_bit_buffer *wb, int delta_q) {
   if (delta_q != 0) {
     vp9_wb_write_bit(wb, 1);
     vp9_wb_write_literal(wb, abs(delta_q), 4);
     vp9_wb_write_bit(wb, delta_q < 0);
   } else {
     vp9_wb_write_bit(wb, 0);
   }
 }
 static void encode_quantization(VP9_COMMON *cm,
                                 struct vp9_write_bit_buffer *wb) {
   vp9_wb_write_literal(wb, cm->base_qindex, QINDEX_BITS);
   write_delta_q(wb, cm->y_dc_delta_q);
   write_delta_q(wb, cm->uv_dc_delta_q);
   write_delta_q(wb, cm->uv_ac_delta_q);
 }
 static void encode_segmentation(VP9_COMP *cpi,
                                 struct vp9_write_bit_buffer *wb) {
   int i, j;
   struct segmentation *seg = &cpi->common.seg;
   vp9_wb_write_bit(wb, seg->enabled);
   if (!seg->enabled)
     return;
   // Segmentation map
   vp9_wb_write_bit(wb, seg->update_map);
   if (seg->update_map) {
     // Select the coding strategy (temporal or spatial)
     vp9_choose_segmap_coding_method(cpi);
     // Write out probabilities used to decode unpredicted  macro-block segments
     for (i = 0; i < SEG_TREE_PROBS; i++) {
       const int prob = seg->tree_probs[i];
       const int update = prob != MAX_PROB;
       vp9_wb_write_bit(wb, update);
       if (update)
         vp9_wb_write_literal(wb, prob, 8);
     }
     // Write out the chosen coding method.
     vp9_wb_write_bit(wb, seg->temporal_update);
     if (seg->temporal_update) {
       for (i = 0; i < PREDICTION_PROBS; i++) {
         const int prob = seg->pred_probs[i];
         const int update = prob != MAX_PROB;
         vp9_wb_write_bit(wb, update);
         if (update)
           vp9_wb_write_literal(wb, prob, 8);
       }
     }
   }
   // Segmentation data
   vp9_wb_write_bit(wb, seg->update_data);
   if (seg->update_data) {
     vp9_wb_write_bit(wb, seg->abs_delta);
     for (i = 0; i < MAX_SEGMENTS; i++) {
       for (j = 0; j < SEG_LVL_MAX; j++) {
         const int active = vp9_segfeature_active(seg, i, j);
         vp9_wb_write_bit(wb, active);
         if (active) {
           const int data = vp9_get_segdata(seg, i, j);
           const int data_max = vp9_seg_feature_data_max(j);
           if (vp9_is_segfeature_signed(j)) {
             vp9_encode_unsigned_max(wb, abs(data), data_max);
             vp9_wb_write_bit(wb, data < 0);
           } else {
             vp9_encode_unsigned_max(wb, data, data_max);
           }
         }
       }
     }
   }
 }
 static void encode_txfm_probs(VP9_COMP *cpi, vp9_writer *w) {
   VP9_COMMON *const cm = &cpi->common;
   // Mode
   vp9_write_literal(w, MIN(cm->tx_mode, ALLOW_32X32), 2);
   if (cm->tx_mode >= ALLOW_32X32)
     vp9_write_bit(w, cm->tx_mode == TX_MODE_SELECT);
   // Probabilities
   if (cm->tx_mode == TX_MODE_SELECT) {
     int i, j;
     unsigned int ct_8x8p[TX_SIZES - 3][2];
     unsigned int ct_16x16p[TX_SIZES - 2][2];
     unsigned int ct_32x32p[TX_SIZES - 1][2];
     for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
       tx_counts_to_branch_counts_8x8(cm->counts.tx.p8x8[i], ct_8x8p);
       for (j = 0; j < TX_SIZES - 3; j++)
         vp9_cond_prob_diff_update(w, &cm->fc.tx_probs.p8x8[i][j], ct_8x8p[j]);
     }
     for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
       tx_counts_to_branch_counts_16x16(cm->counts.tx.p16x16[i], ct_16x16p);
       for (j = 0; j < TX_SIZES - 2; j++)
         vp9_cond_prob_diff_update(w, &cm->fc.tx_probs.p16x16[i][j],
                                   ct_16x16p[j]);
     }
     for (i = 0; i < TX_SIZE_CONTEXTS; i++) {
       tx_counts_to_branch_counts_32x32(cm->counts.tx.p32x32[i], ct_32x32p);
       for (j = 0; j < TX_SIZES - 1; j++)
         vp9_cond_prob_diff_update(w, &cm->fc.tx_probs.p32x32[i][j],
                                   ct_32x32p[j]);
     }
 #ifdef MODE_STATS
     if (!cpi->dummy_packing)
       update_tx_count_stats(cm);
 #endif
   }
 }
 static void write_interp_filter_type(INTERPOLATION_TYPE type,
                                      struct vp9_write_bit_buffer *wb) {
   const int type_to_literal[] = { 1, 0, 2, 3 };
   vp9_wb_write_bit(wb, type == SWITCHABLE);
   if (type != SWITCHABLE)
     vp9_wb_write_literal(wb, type_to_literal[type], 2);
 }
 static void fix_mcomp_filter_type(VP9_COMP *cpi) {
   VP9_COMMON *const cm = &cpi->common;
   if (cm->mcomp_filter_type == SWITCHABLE) {
     // Check to see if only one of the filters is actually used
     int count[SWITCHABLE_FILTERS];
     int i, j, c = 0;
     for (i = 0; i < SWITCHABLE_FILTERS; ++i) {
       count[i] = 0;
       for (j = 0; j < SWITCHABLE_FILTER_CONTEXTS; ++j)
         count[i] += cm->counts.switchable_interp[j][i];
       c += (count[i] > 0);
     }
     if (c == 1) {
       // Only one filter is used. So set the filter at frame level
       for (i = 0; i < SWITCHABLE_FILTERS; ++i) {
         if (count[i]) {
           cm->mcomp_filter_type = i;
           break;
         }
       }
     }
   }
 }
 static void write_tile_info(VP9_COMMON *cm, struct vp9_write_bit_buffer *wb) {
   int min_log2_tile_cols, max_log2_tile_cols, ones;
   vp9_get_tile_n_bits(cm->mi_cols, &min_log2_tile_cols, &max_log2_tile_cols);
   // columns
   ones = cm->log2_tile_cols - min_log2_tile_cols;
   while (ones--)
     vp9_wb_write_bit(wb, 1);
   if (cm->log2_tile_cols < max_log2_tile_cols)
     vp9_wb_write_bit(wb, 0);
   // rows
   vp9_wb_write_bit(wb, cm->log2_tile_rows != 0);
   if (cm->log2_tile_rows != 0)
     vp9_wb_write_bit(wb, cm->log2_tile_rows != 1);
 }
 static int get_refresh_mask(VP9_COMP *cpi) {
     // Should the GF or ARF be updated using the transmitted frame or buffer
 #if CONFIG_MULTIPLE_ARF
     if (!cpi->multi_arf_enabled && cpi->refresh_golden_frame &&
         !cpi->refresh_alt_ref_frame) {
 #else
     if (cpi->refresh_golden_frame && !cpi->refresh_alt_ref_frame &&
         !cpi->use_svc) {
 #endif
       // Preserve the previously existing golden frame and update the frame in
       // the alt ref slot instead. This is highly specific to the use of
       // alt-ref as a forward reference, and this needs to be generalized as
       // other uses are implemented (like RTC/temporal scaling)
       //
       // gld_fb_idx and alt_fb_idx need to be swapped for future frames, but
       // that happens in vp9_onyx_if.c:update_reference_frames() so that it can
       // be done outside of the recode loop.
       return (cpi->refresh_last_frame << cpi->lst_fb_idx) |
              (cpi->refresh_golden_frame << cpi->alt_fb_idx);
     } else {
       int arf_idx = cpi->alt_fb_idx;
 #if CONFIG_MULTIPLE_ARF
       // Determine which ARF buffer to use to encode this ARF frame.
       if (cpi->multi_arf_enabled) {
         int sn = cpi->sequence_number;
         arf_idx = (cpi->frame_coding_order[sn] < 0) ?
             cpi->arf_buffer_idx[sn + 1] :
             cpi->arf_buffer_idx[sn];
       }
 #endif
       return (cpi->refresh_last_frame << cpi->lst_fb_idx) |
              (cpi->refresh_golden_frame << cpi->gld_fb_idx) |
              (cpi->refresh_alt_ref_frame << arf_idx);
     }
 }
 static size_t encode_tiles(VP9_COMP *cpi, uint8_t *data_ptr) {
   VP9_COMMON *const cm = &cpi->common;
   vp9_writer residual_bc;
   int tile_row, tile_col;
   TOKENEXTRA *tok[4][1 << 6], *tok_end;
   size_t total_size = 0;
   const int tile_cols = 1 << cm->log2_tile_cols;
   const int tile_rows = 1 << cm->log2_tile_rows;
   vpx_memset(cpi->above_seg_context, 0, sizeof(*cpi->above_seg_context) *
              mi_cols_aligned_to_sb(cm->mi_cols));
   tok[0][0] = cpi->tok;
   for (tile_row = 0; tile_row < tile_rows; tile_row++) {
     if (tile_row)
       tok[tile_row][0] = tok[tile_row - 1][tile_cols - 1] +
                          cpi->tok_count[tile_row - 1][tile_cols - 1];
     for (tile_col = 1; tile_col < tile_cols; tile_col++)
       tok[tile_row][tile_col] = tok[tile_row][tile_col - 1] +
                                 cpi->tok_count[tile_row][tile_col - 1];
   }
   for (tile_row = 0; tile_row < tile_rows; tile_row++) {
     for (tile_col = 0; tile_col < tile_cols; tile_col++) {
       TileInfo tile;
       vp9_tile_init(&tile, cm, tile_row, tile_col);
       tok_end = tok[tile_row][tile_col] + cpi->tok_count[tile_row][tile_col];
       if (tile_col < tile_cols - 1 || tile_row < tile_rows - 1)
         vp9_start_encode(&residual_bc, data_ptr + total_size + 4);
       else
         vp9_start_encode(&residual_bc, data_ptr + total_size);
       write_modes(cpi, &tile, &residual_bc, &tok[tile_row][tile_col], tok_end);
       assert(tok[tile_row][tile_col] == tok_end);
       vp9_stop_encode(&residual_bc);
       if (tile_col < tile_cols - 1 || tile_row < tile_rows - 1) {
         // size of this tile
         write_be32(data_ptr + total_size, residual_bc.pos);
         total_size += 4;
       }
       total_size += residual_bc.pos;
     }
   }
   return total_size;
 }
 static void write_display_size(VP9_COMP *cpi, struct vp9_write_bit_buffer *wb) {
   VP9_COMMON *const cm = &cpi->common;
   const int scaling_active = cm->width != cm->display_width ||
                              cm->height != cm->display_height;
   vp9_wb_write_bit(wb, scaling_active);
   if (scaling_active) {
     vp9_wb_write_literal(wb, cm->display_width - 1, 16);
     vp9_wb_write_literal(wb, cm->display_height - 1, 16);
   }
 }
 static void write_frame_size(VP9_COMP *cpi,
                              struct vp9_write_bit_buffer *wb) {
   VP9_COMMON *const cm = &cpi->common;
   vp9_wb_write_literal(wb, cm->width - 1, 16);
   vp9_wb_write_literal(wb, cm->height - 1, 16);
   write_display_size(cpi, wb);
 }
 static void write_frame_size_with_refs(VP9_COMP *cpi,
                                        struct vp9_write_bit_buffer *wb) {
   VP9_COMMON *const cm = &cpi->common;
   int refs[ALLOWED_REFS_PER_FRAME] = {cpi->lst_fb_idx, cpi->gld_fb_idx,
                                       cpi->alt_fb_idx};
   int i, found = 0;
   for (i = 0; i < ALLOWED_REFS_PER_FRAME; ++i) {
     YV12_BUFFER_CONFIG *cfg = &cm->yv12_fb[cm->ref_frame_map[refs[i]]];
     found = cm->width == cfg->y_crop_width &&
             cm->height == cfg->y_crop_height;
     // TODO(ivan): This prevents a bug while more than 3 buffers are used. Do it
     // in a better way.
     if (cpi->use_svc) {
       found = 0;
     }
     vp9_wb_write_bit(wb, found);
     if (found) {
       break;
     }
   }
   if (!found) {
     vp9_wb_write_literal(wb, cm->width - 1, 16);
     vp9_wb_write_literal(wb, cm->height - 1, 16);
   }
   write_display_size(cpi, wb);
 }
 static void write_sync_code(struct vp9_write_bit_buffer *wb) {
   vp9_wb_write_literal(wb, VP9_SYNC_CODE_0, 8);
   vp9_wb_write_literal(wb, VP9_SYNC_CODE_1, 8);
   vp9_wb_write_literal(wb, VP9_SYNC_CODE_2, 8);
 }
 static void write_uncompressed_header(VP9_COMP *cpi,
                                       struct vp9_write_bit_buffer *wb) {
   VP9_COMMON *const cm = &cpi->common;
   vp9_wb_write_literal(wb, VP9_FRAME_MARKER, 2);
   // bitstream version.
   // 00 - profile 0. 4:2:0 only
   // 10 - profile 1. adds 4:4:4, 4:2:2, alpha
   vp9_wb_write_bit(wb, cm->version);
   vp9_wb_write_bit(wb, 0);
   vp9_wb_write_bit(wb, 0);
   vp9_wb_write_bit(wb, cm->frame_type);
   vp9_wb_write_bit(wb, cm->show_frame);
   vp9_wb_write_bit(wb, cm->error_resilient_mode);
   if (cm->frame_type == KEY_FRAME) {
     const COLOR_SPACE cs = UNKNOWN;
     write_sync_code(wb);
     vp9_wb_write_literal(wb, cs, 3);
     if (cs != SRGB) {
       vp9_wb_write_bit(wb, 0);  // 0: [16, 235] (i.e. xvYCC), 1: [0, 255]
       if (cm->version == 1) {
         vp9_wb_write_bit(wb, cm->subsampling_x);
         vp9_wb_write_bit(wb, cm->subsampling_y);
         vp9_wb_write_bit(wb, 0);  // has extra plane
       }
     } else {
       assert(cm->version == 1);
       vp9_wb_write_bit(wb, 0);  // has extra plane
     }
     write_frame_size(cpi, wb);
   } else {
     const int refs[ALLOWED_REFS_PER_FRAME] = {cpi->lst_fb_idx, cpi->gld_fb_idx,
                                               cpi->alt_fb_idx};
     if (!cm->show_frame)
       vp9_wb_write_bit(wb, cm->intra_only);
     if (!cm->error_resilient_mode)
       vp9_wb_write_literal(wb, cm->reset_frame_context, 2);
     if (cm->intra_only) {
       write_sync_code(wb);
       vp9_wb_write_literal(wb, get_refresh_mask(cpi), NUM_REF_FRAMES);
       write_frame_size(cpi, wb);
     } else {
       int i;
       vp9_wb_write_literal(wb, get_refresh_mask(cpi), NUM_REF_FRAMES);
       for (i = 0; i < ALLOWED_REFS_PER_FRAME; ++i) {
         vp9_wb_write_literal(wb, refs[i], NUM_REF_FRAMES_LOG2);
         vp9_wb_write_bit(wb, cm->ref_frame_sign_bias[LAST_FRAME + i]);
       }
       write_frame_size_with_refs(cpi, wb);
       vp9_wb_write_bit(wb, cm->allow_high_precision_mv);
       fix_mcomp_filter_type(cpi);
       write_interp_filter_type(cm->mcomp_filter_type, wb);
     }
   }
   if (!cm->error_resilient_mode) {
     vp9_wb_write_bit(wb, cm->refresh_frame_context);
     vp9_wb_write_bit(wb, cm->frame_parallel_decoding_mode);
   }
   vp9_wb_write_literal(wb, cm->frame_context_idx, NUM_FRAME_CONTEXTS_LOG2);
   encode_loopfilter(&cm->lf, wb);
   encode_quantization(cm, wb);
   encode_segmentation(cpi, wb);
   write_tile_info(cm, wb);
 }
 static size_t write_compressed_header(VP9_COMP *cpi, uint8_t *data) {
   VP9_COMMON *const cm = &cpi->common;
   MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   FRAME_CONTEXT *const fc = &cm->fc;
   vp9_writer header_bc;
   vp9_start_encode(&header_bc, data);
   if (xd->lossless)
     cm->tx_mode = ONLY_4X4;
   else
     encode_txfm_probs(cpi, &header_bc);
   update_coef_probs(cpi, &header_bc);
 #ifdef ENTROPY_STATS
   active_section = 2;
 #endif
   vp9_update_skip_probs(cpi, &header_bc);
   if (!frame_is_intra_only(cm)) {
     int i;
 #ifdef ENTROPY_STATS
     active_section = 1;
 #endif
     update_inter_mode_probs(cm, &header_bc);
     vp9_zero(cm->counts.inter_mode);
     if (cm->mcomp_filter_type == SWITCHABLE)
       update_switchable_interp_probs(cpi, &header_bc);
     for (i = 0; i < INTRA_INTER_CONTEXTS; i++)
       vp9_cond_prob_diff_update(&header_bc, &fc->intra_inter_prob[i],
                                 cpi->intra_inter_count[i]);
     if (cm->allow_comp_inter_inter) {
       const int comp_pred_mode = cpi->common.comp_pred_mode;
       const int use_compound_pred = comp_pred_mode != SINGLE_PREDICTION_ONLY;
       const int use_hybrid_pred = comp_pred_mode == HYBRID_PREDICTION;
       vp9_write_bit(&header_bc, use_compound_pred);
       if (use_compound_pred) {
         vp9_write_bit(&header_bc, use_hybrid_pred);
         if (use_hybrid_pred)
           for (i = 0; i < COMP_INTER_CONTEXTS; i++)
             vp9_cond_prob_diff_update(&header_bc, &fc->comp_inter_prob[i],
                                       cpi->comp_inter_count[i]);
       }
     }
     if (cm->comp_pred_mode != COMP_PREDICTION_ONLY) {
       for (i = 0; i < REF_CONTEXTS; i++) {
         vp9_cond_prob_diff_update(&header_bc, &fc->single_ref_prob[i][0],
                                   cpi->single_ref_count[i][0]);
         vp9_cond_prob_diff_update(&header_bc, &fc->single_ref_prob[i][1],
                                   cpi->single_ref_count[i][1]);
       }
     }
     if (cm->comp_pred_mode != SINGLE_PREDICTION_ONLY)
       for (i = 0; i < REF_CONTEXTS; i++)
         vp9_cond_prob_diff_update(&header_bc, &fc->comp_ref_prob[i],
                                   cpi->comp_ref_count[i]);
     update_mbintra_mode_probs(cpi, &header_bc);
     for (i = 0; i < PARTITION_CONTEXTS; ++i) {
       unsigned int bct[PARTITION_TYPES - 1][2];
       update_mode(&header_bc, PARTITION_TYPES, vp9_partition_tree,
                   fc->partition_prob[i], bct,
                   (unsigned int *)cpi->partition_count[i]);
     }
     vp9_write_nmv_probs(cpi, cm->allow_high_precision_mv, &header_bc);
   }
   vp9_stop_encode(&header_bc);
   assert(header_bc.pos <= 0xffff);
   return header_bc.pos;
 }
 void vp9_pack_bitstream(VP9_COMP *cpi, uint8_t *dest, unsigned long *size) {
   uint8_t *data = dest;
   size_t first_part_size;
   struct vp9_write_bit_buffer wb = {data, 0};
   struct vp9_write_bit_buffer saved_wb;
   write_uncompressed_header(cpi, &wb);
   saved_wb = wb;
   vp9_wb_write_literal(&wb, 0, 16);  // don't know in advance first part. size
   data += vp9_rb_bytes_written(&wb);
   vp9_compute_update_table();
 #ifdef ENTROPY_STATS
   if (cm->frame_type == INTER_FRAME)
     active_section = 0;
   else
     active_section = 7;
 #endif
   vp9_clear_system_state();  // __asm emms;
   first_part_size = write_compressed_header(cpi, data);
   data += first_part_size;
   vp9_wb_write_literal(&saved_wb, first_part_size, 16);
   data += encode_tiles(cpi, data);
   *size = data - dest;
 }
 #ifdef ENTROPY_STATS
 static void print_tree_update_for_type(FILE *f,
                                        vp9_coeff_stats *tree_update_hist,
                                        int block_types, const char *header) {
   int i, j, k, l, m;
   fprintf(f, "const vp9_coeff_prob %s = {\n", header);
   for (i = 0; i < block_types; i++) {
     fprintf(f, "  { \n");
     for (j = 0; j < REF_TYPES; j++) {
       fprintf(f, "  { \n");
       for (k = 0; k < COEF_BANDS; k++) {
         fprintf(f, "    {\n");
         for (l = 0; l < PREV_COEF_CONTEXTS; l++) {
           fprintf(f, "      {");
           for (m = 0; m < ENTROPY_NODES; m++) {
             fprintf(f, "%3d, ",
                     get_binary_prob(tree_update_hist[i][j][k][l][m][0],
                                     tree_update_hist[i][j][k][l][m][1]));
           }
           fprintf(f, "},\n");
         }
         fprintf(f, "},\n");
       }
       fprintf(f, "    },\n");
     }
     fprintf(f, "  },\n");
   }
   fprintf(f, "};\n");
 }
 void print_tree_update_probs() {
   FILE *f = fopen("coefupdprob.h", "w");
   fprintf(f, "\n/* Update probabilities for token entropy tree. */\n\n");
   print_tree_update_for_type(f, tree_update_hist[TX_4X4],   BLOCK_TYPES,
                              "vp9_coef_update_probs_4x4[BLOCK_TYPES]");
   print_tree_update_for_type(f, tree_update_hist[TX_8X8],   BLOCK_TYPES,
                              "vp9_coef_update_probs_8x8[BLOCK_TYPES]");
   print_tree_update_for_type(f, tree_update_hist[TX_16X16], BLOCK_TYPES,
                              "vp9_coef_update_probs_16x16[BLOCK_TYPES]");
   print_tree_update_for_type(f, tree_update_hist[TX_32X32], BLOCK_TYPES,
                              "vp9_coef_update_probs_32x32[BLOCK_TYPES]");
   fclose(f);
   f = fopen("treeupdate.bin", "wb");
   fwrite(tree_update_hist, sizeof(tree_update_hist), 1, f);
   fclose(f);
 }
 #endif

The Tor Browser / annotate

media/libvpx/vp9/encoder/vp9_bitstream.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_bitstream.c