src/third_party/libvpx/vp8/common/findnearmv.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 "findnearmv.h"

const unsigned char vp8_mbsplit_offset[4][16] = {
  { 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 2, 8, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }
};

/* Predict motion vectors using those from already-decoded nearby blocks.
   Note that we only consider one 4x4 subblock from each candidate 16x16
   macroblock.   */
void vp8_find_near_mvs(MACROBLOCKD *xd, const MODE_INFO *here, int_mv *nearest,
                       int_mv *nearby, int_mv *best_mv, int near_mv_ref_cnts[4],
                       int refframe, int *ref_frame_sign_bias) {
  const MODE_INFO *above = here - xd->mode_info_stride;
  const MODE_INFO *left = here - 1;
  const MODE_INFO *aboveleft = above - 1;
  int_mv near_mvs[4];
  int_mv *mv = near_mvs;
  int *cntx = near_mv_ref_cnts;
  enum { CNT_INTRA, CNT_NEAREST, CNT_NEAR, CNT_SPLITMV };

  /* Zero accumulators */
  mv[0].as_int = mv[1].as_int = mv[2].as_int = 0;
  near_mv_ref_cnts[0] = near_mv_ref_cnts[1] = near_mv_ref_cnts[2] =
      near_mv_ref_cnts[3] = 0;

  /* Process above */
  if (above->mbmi.ref_frame != INTRA_FRAME) {
    if (above->mbmi.mv.as_int) {
      (++mv)->as_int = above->mbmi.mv.as_int;
      mv_bias(ref_frame_sign_bias[above->mbmi.ref_frame], refframe, mv,
              ref_frame_sign_bias);
      ++cntx;
    }

    *cntx += 2;
  }

  /* Process left */
  if (left->mbmi.ref_frame != INTRA_FRAME) {
    if (left->mbmi.mv.as_int) {
      int_mv this_mv;

      this_mv.as_int = left->mbmi.mv.as_int;
      mv_bias(ref_frame_sign_bias[left->mbmi.ref_frame], refframe, &this_mv,
              ref_frame_sign_bias);

      if (this_mv.as_int != mv->as_int) {
        (++mv)->as_int = this_mv.as_int;
        ++cntx;
      }

      *cntx += 2;
    } else {
      near_mv_ref_cnts[CNT_INTRA] += 2;
    }
  }

  /* Process above left */
  if (aboveleft->mbmi.ref_frame != INTRA_FRAME) {
    if (aboveleft->mbmi.mv.as_int) {
      int_mv this_mv;

      this_mv.as_int = aboveleft->mbmi.mv.as_int;
      mv_bias(ref_frame_sign_bias[aboveleft->mbmi.ref_frame], refframe,
              &this_mv, ref_frame_sign_bias);

      if (this_mv.as_int != mv->as_int) {
        (++mv)->as_int = this_mv.as_int;
        ++cntx;
      }

      *cntx += 1;
    } else {
      near_mv_ref_cnts[CNT_INTRA] += 1;
    }
  }

  /* If we have three distinct MV's ... */
  if (near_mv_ref_cnts[CNT_SPLITMV]) {
    /* See if above-left MV can be merged with NEAREST */
    if (mv->as_int == near_mvs[CNT_NEAREST].as_int)
      near_mv_ref_cnts[CNT_NEAREST] += 1;
  }

  near_mv_ref_cnts[CNT_SPLITMV] =
      ((above->mbmi.mode == SPLITMV) + (left->mbmi.mode == SPLITMV)) * 2 +
      (aboveleft->mbmi.mode == SPLITMV);

  /* Swap near and nearest if necessary */
  if (near_mv_ref_cnts[CNT_NEAR] > near_mv_ref_cnts[CNT_NEAREST]) {
    int tmp;
    tmp = near_mv_ref_cnts[CNT_NEAREST];
    near_mv_ref_cnts[CNT_NEAREST] = near_mv_ref_cnts[CNT_NEAR];
    near_mv_ref_cnts[CNT_NEAR] = tmp;
    tmp = near_mvs[CNT_NEAREST].as_int;
    near_mvs[CNT_NEAREST].as_int = near_mvs[CNT_NEAR].as_int;
    near_mvs[CNT_NEAR].as_int = tmp;
  }

  /* Use near_mvs[0] to store the "best" MV */
  if (near_mv_ref_cnts[CNT_NEAREST] >= near_mv_ref_cnts[CNT_INTRA]) {
    near_mvs[CNT_INTRA] = near_mvs[CNT_NEAREST];
  }

  /* Set up return values */
  best_mv->as_int = near_mvs[0].as_int;
  nearest->as_int = near_mvs[CNT_NEAREST].as_int;
  nearby->as_int = near_mvs[CNT_NEAR].as_int;
}

static void invert_and_clamp_mvs(int_mv *inv, int_mv *src, MACROBLOCKD *xd) {
  inv->as_mv.row = src->as_mv.row * -1;
  inv->as_mv.col = src->as_mv.col * -1;
  vp8_clamp_mv2(inv, xd);
  vp8_clamp_mv2(src, xd);
}

int vp8_find_near_mvs_bias(MACROBLOCKD *xd, const MODE_INFO *here,
                           int_mv mode_mv_sb[2][MB_MODE_COUNT],
                           int_mv best_mv_sb[2], int cnt[4], int refframe,
                           int *ref_frame_sign_bias) {
  int sign_bias = ref_frame_sign_bias[refframe];

  vp8_find_near_mvs(xd, here, &mode_mv_sb[sign_bias][NEARESTMV],
                    &mode_mv_sb[sign_bias][NEARMV], &best_mv_sb[sign_bias], cnt,
                    refframe, ref_frame_sign_bias);

  invert_and_clamp_mvs(&mode_mv_sb[!sign_bias][NEARESTMV],
                       &mode_mv_sb[sign_bias][NEARESTMV], xd);
  invert_and_clamp_mvs(&mode_mv_sb[!sign_bias][NEARMV],
                       &mode_mv_sb[sign_bias][NEARMV], xd);
  invert_and_clamp_mvs(&best_mv_sb[!sign_bias], &best_mv_sb[sign_bias], xd);

  return sign_bias;
}

vp8_prob *vp8_mv_ref_probs(vp8_prob p[VP8_MVREFS - 1],
                           const int near_mv_ref_ct[4]) {
  p[0] = vp8_mode_contexts[near_mv_ref_ct[0]][0];
  p[1] = vp8_mode_contexts[near_mv_ref_ct[1]][1];
  p[2] = vp8_mode_contexts[near_mv_ref_ct[2]][2];
  p[3] = vp8_mode_contexts[near_mv_ref_ct[3]][3];
  /* p[3] = vp8_mode_contexts[near_mv_ref_ct[1] + near_mv_ref_ct[2] +
                           near_mv_ref_ct[3]][3]; */
  return p;
}