path: root/libvpx/vp8/encoder/encodemv.c

/*
 *  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 "vp8/common/common.h"
#include "encodemv.h"
#include "vp8/common/entropymode.h"
#include "vp8/common/systemdependent.h"
#include "vpx_ports/system_state.h"

#include <math.h>

static void encode_mvcomponent(vp8_writer *const w, const int v,
                               const struct mv_context *mvc) {
  const vp8_prob *p = mvc->prob;
  const int x = v < 0 ? -v : v;

  if (x < mvnum_short) { /* Small */
    vp8_write(w, 0, p[mvpis_short]);
    vp8_treed_write(w, vp8_small_mvtree, p + MVPshort, x, 3);

    if (!x) return; /* no sign bit */
  } else {          /* Large */
    int i = 0;

    vp8_write(w, 1, p[mvpis_short]);

    do
      vp8_write(w, (x >> i) & 1, p[MVPbits + i]);

    while (++i < 3);

    i = mvlong_width - 1; /* Skip bit 3, which is sometimes implicit */

    do
      vp8_write(w, (x >> i) & 1, p[MVPbits + i]);

    while (--i > 3);

    if (x & 0xFFF0) vp8_write(w, (x >> 3) & 1, p[MVPbits + 3]);
  }

  vp8_write(w, v < 0, p[MVPsign]);
}
#if 0
static int max_mv_r = 0;
static int max_mv_c = 0;
#endif
void vp8_encode_motion_vector(vp8_writer *w, const MV *mv,
                              const MV_CONTEXT *mvc) {
#if 0
    {
        if (abs(mv->row >> 1) > max_mv_r)
        {
            FILE *f = fopen("maxmv.stt", "a");
            max_mv_r = abs(mv->row >> 1);
            fprintf(f, "New Mv Row Max %6d\n", (mv->row >> 1));

            if ((abs(mv->row) / 2) != max_mv_r)
                fprintf(f, "MV Row conversion error %6d\n", abs(mv->row) / 2);

            fclose(f);
        }

        if (abs(mv->col >> 1) > max_mv_c)
        {
            FILE *f = fopen("maxmv.stt", "a");
            fprintf(f, "New Mv Col Max %6d\n", (mv->col >> 1));
            max_mv_c = abs(mv->col >> 1);
            fclose(f);
        }
    }
#endif

  encode_mvcomponent(w, mv->row >> 1, &mvc[0]);
  encode_mvcomponent(w, mv->col >> 1, &mvc[1]);
}

static unsigned int cost_mvcomponent(const int v,
                                     const struct mv_context *mvc) {
  const vp8_prob *p = mvc->prob;
  const int x = v;
  unsigned int cost;

  if (x < mvnum_short) {
    cost = vp8_cost_zero(p[mvpis_short]) +
           vp8_treed_cost(vp8_small_mvtree, p + MVPshort, x, 3);

    if (!x) return cost;
  } else {
    int i = 0;
    cost = vp8_cost_one(p[mvpis_short]);

    do {
      cost += vp8_cost_bit(p[MVPbits + i], (x >> i) & 1);

    } while (++i < 3);

    i = mvlong_width - 1; /* Skip bit 3, which is sometimes implicit */

    do {
      cost += vp8_cost_bit(p[MVPbits + i], (x >> i) & 1);

    } while (--i > 3);

    if (x & 0xFFF0) cost += vp8_cost_bit(p[MVPbits + 3], (x >> 3) & 1);
  }

  return cost; /* + vp8_cost_bit( p [MVPsign], v < 0); */
}

void vp8_build_component_cost_table(int *mvcost[2], const MV_CONTEXT *mvc,
                                    int mvc_flag[2]) {
  int i = 1;
  unsigned int cost0 = 0;
  unsigned int cost1 = 0;

  vpx_clear_system_state();

  i = 1;

  if (mvc_flag[0]) {
    mvcost[0][0] = cost_mvcomponent(0, &mvc[0]);

    do {
      cost0 = cost_mvcomponent(i, &mvc[0]);

      mvcost[0][i] = cost0 + vp8_cost_zero(mvc[0].prob[MVPsign]);
      mvcost[0][-i] = cost0 + vp8_cost_one(mvc[0].prob[MVPsign]);
    } while (++i <= mv_max);
  }

  i = 1;

  if (mvc_flag[1]) {
    mvcost[1][0] = cost_mvcomponent(0, &mvc[1]);

    do {
      cost1 = cost_mvcomponent(i, &mvc[1]);

      mvcost[1][i] = cost1 + vp8_cost_zero(mvc[1].prob[MVPsign]);
      mvcost[1][-i] = cost1 + vp8_cost_one(mvc[1].prob[MVPsign]);
    } while (++i <= mv_max);
  }
}

/* Motion vector probability table update depends on benefit.
 * Small correction allows for the fact that an update to an MV probability
 * may have benefit in subsequent frames as well as the current one.
 */
#define MV_PROB_UPDATE_CORRECTION -1

static void calc_prob(vp8_prob *p, const unsigned int ct[2]) {
  const unsigned int tot = ct[0] + ct[1];

  if (tot) {
    const vp8_prob x = ((ct[0] * 255) / tot) & ~1u;
    *p = x ? x : 1;
  }
}

static void update(vp8_writer *const w, const unsigned int ct[2],
                   vp8_prob *const cur_p, const vp8_prob new_p,
                   const vp8_prob update_p, int *updated) {
  const int cur_b = vp8_cost_branch(ct, *cur_p);
  const int new_b = vp8_cost_branch(ct, new_p);
  const int cost =
      7 + MV_PROB_UPDATE_CORRECTION +
      ((vp8_cost_one(update_p) - vp8_cost_zero(update_p) + 128) >> 8);

  if (cur_b - new_b > cost) {
    *cur_p = new_p;
    vp8_write(w, 1, update_p);
    vp8_write_literal(w, new_p >> 1, 7);
    *updated = 1;

  } else
    vp8_write(w, 0, update_p);
}

static void write_component_probs(vp8_writer *const w,
                                  struct mv_context *cur_mvc,
                                  const struct mv_context *default_mvc_,
                                  const struct mv_context *update_mvc,
                                  const unsigned int events[MVvals],
                                  unsigned int rc, int *updated) {
  vp8_prob *Pcur = cur_mvc->prob;
  const vp8_prob *default_mvc = default_mvc_->prob;
  const vp8_prob *Pupdate = update_mvc->prob;
  unsigned int is_short_ct[2], sign_ct[2];

  unsigned int bit_ct[mvlong_width][2];

  unsigned int short_ct[mvnum_short];
  unsigned int short_bct[mvnum_short - 1][2];

  vp8_prob Pnew[MVPcount];

  (void)rc;
  vp8_copy_array(Pnew, default_mvc, MVPcount);

  vp8_zero(is_short_ct);
  vp8_zero(sign_ct);
  vp8_zero(bit_ct);
  vp8_zero(short_ct);
  vp8_zero(short_bct);

  /* j=0 */
  {
    const int c = events[mv_max];

    is_short_ct[0] += c; /* Short vector */
    short_ct[0] += c;    /* Magnitude distribution */
  }

  /* j: 1 ~ mv_max (1023) */
  {
    int j = 1;

    do {
      const int c1 = events[mv_max + j]; /* positive */
      const int c2 = events[mv_max - j]; /* negative */
      const int c = c1 + c2;
      int a = j;

      sign_ct[0] += c1;
      sign_ct[1] += c2;

      if (a < mvnum_short) {
        is_short_ct[0] += c; /* Short vector */
        short_ct[a] += c;    /* Magnitude distribution */
      } else {
        int k = mvlong_width - 1;
        is_short_ct[1] += c; /* Long vector */

        /*  bit 3 not always encoded. */
        do {
          bit_ct[k][(a >> k) & 1] += c;

        } while (--k >= 0);
      }
    } while (++j <= mv_max);
  }

  calc_prob(Pnew + mvpis_short, is_short_ct);

  calc_prob(Pnew + MVPsign, sign_ct);

  {
    vp8_prob p[mvnum_short - 1]; /* actually only need branch ct */
    int j = 0;

    vp8_tree_probs_from_distribution(8, vp8_small_mvencodings, vp8_small_mvtree,
                                     p, short_bct, short_ct, 256, 1);

    do {
      calc_prob(Pnew + MVPshort + j, short_bct[j]);

    } while (++j < mvnum_short - 1);
  }

  {
    int j = 0;

    do {
      calc_prob(Pnew + MVPbits + j, bit_ct[j]);

    } while (++j < mvlong_width);
  }

  update(w, is_short_ct, Pcur + mvpis_short, Pnew[mvpis_short], *Pupdate++,
         updated);

  update(w, sign_ct, Pcur + MVPsign, Pnew[MVPsign], *Pupdate++, updated);

  {
    const vp8_prob *const new_p = Pnew + MVPshort;
    vp8_prob *const cur_p = Pcur + MVPshort;

    int j = 0;

    do {
      update(w, short_bct[j], cur_p + j, new_p[j], *Pupdate++, updated);

    } while (++j < mvnum_short - 1);
  }

  {
    const vp8_prob *const new_p = Pnew + MVPbits;
    vp8_prob *const cur_p = Pcur + MVPbits;

    int j = 0;

    do {
      update(w, bit_ct[j], cur_p + j, new_p[j], *Pupdate++, updated);

    } while (++j < mvlong_width);
  }
}

void vp8_write_mvprobs(VP8_COMP *cpi) {
  vp8_writer *const w = cpi->bc;
  MV_CONTEXT *mvc = cpi->common.fc.mvc;
  int flags[2] = { 0, 0 };
  write_component_probs(w, &mvc[0], &vp8_default_mv_context[0],
                        &vp8_mv_update_probs[0], cpi->mb.MVcount[0], 0,
                        &flags[0]);
  write_component_probs(w, &mvc[1], &vp8_default_mv_context[1],
                        &vp8_mv_update_probs[1], cpi->mb.MVcount[1], 1,
                        &flags[1]);

  if (flags[0] || flags[1]) {
    vp8_build_component_cost_table(
        cpi->mb.mvcost, (const MV_CONTEXT *)cpi->common.fc.mvc, flags);
  }
}