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      1 /*
      2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
      3  *
      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.
      9  */
     10 
     11 
     12 #include "findnearmv.h"
     13 
     14 const unsigned char vp8_mbsplit_offset[4][16] = {
     15     { 0,  8,  0,  0,  0,  0,  0,  0,  0,  0,   0,  0,  0,  0,  0,  0},
     16     { 0,  2,  0,  0,  0,  0,  0,  0,  0,  0,   0,  0,  0,  0,  0,  0},
     17     { 0,  2,  8, 10,  0,  0,  0,  0,  0,  0,   0,  0,  0,  0,  0,  0},
     18     { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15}
     19 };
     20 
     21 /* Predict motion vectors using those from already-decoded nearby blocks.
     22    Note that we only consider one 4x4 subblock from each candidate 16x16
     23    macroblock.   */
     24 void vp8_find_near_mvs
     25 (
     26     MACROBLOCKD *xd,
     27     const MODE_INFO *here,
     28     MV *nearest,
     29     MV *nearby,
     30     MV *best_mv,
     31     int cnt[4],
     32     int refframe,
     33     int *ref_frame_sign_bias
     34 )
     35 {
     36     const MODE_INFO *above = here - xd->mode_info_stride;
     37     const MODE_INFO *left = here - 1;
     38     const MODE_INFO *aboveleft = above - 1;
     39     int_mv            near_mvs[4];
     40     int_mv           *mv = near_mvs;
     41     int             *cntx = cnt;
     42     enum {CNT_INTRA, CNT_NEAREST, CNT_NEAR, CNT_SPLITMV};
     43 
     44     /* Zero accumulators */
     45     mv[0].as_int = mv[1].as_int = mv[2].as_int = 0;
     46     cnt[0] = cnt[1] = cnt[2] = cnt[3] = 0;
     47 
     48     /* Process above */
     49     if (above->mbmi.ref_frame != INTRA_FRAME)
     50     {
     51         if (above->mbmi.mv.as_int)
     52         {
     53             (++mv)->as_int = above->mbmi.mv.as_int;
     54             mv_bias(ref_frame_sign_bias[above->mbmi.ref_frame], refframe, mv, ref_frame_sign_bias);
     55             ++cntx;
     56         }
     57 
     58         *cntx += 2;
     59     }
     60 
     61     /* Process left */
     62     if (left->mbmi.ref_frame != INTRA_FRAME)
     63     {
     64         if (left->mbmi.mv.as_int)
     65         {
     66             int_mv this_mv;
     67 
     68             this_mv.as_int = left->mbmi.mv.as_int;
     69             mv_bias(ref_frame_sign_bias[left->mbmi.ref_frame], refframe, &this_mv, ref_frame_sign_bias);
     70 
     71             if (this_mv.as_int != mv->as_int)
     72             {
     73                 (++mv)->as_int = this_mv.as_int;
     74                 ++cntx;
     75             }
     76 
     77             *cntx += 2;
     78         }
     79         else
     80             cnt[CNT_INTRA] += 2;
     81     }
     82 
     83     /* Process above left */
     84     if (aboveleft->mbmi.ref_frame != INTRA_FRAME)
     85     {
     86         if (aboveleft->mbmi.mv.as_int)
     87         {
     88             int_mv this_mv;
     89 
     90             this_mv.as_int = aboveleft->mbmi.mv.as_int;
     91             mv_bias(ref_frame_sign_bias[aboveleft->mbmi.ref_frame], refframe, &this_mv, ref_frame_sign_bias);
     92 
     93             if (this_mv.as_int != mv->as_int)
     94             {
     95                 (++mv)->as_int = this_mv.as_int;
     96                 ++cntx;
     97             }
     98 
     99             *cntx += 1;
    100         }
    101         else
    102             cnt[CNT_INTRA] += 1;
    103     }
    104 
    105     /* If we have three distinct MV's ... */
    106     if (cnt[CNT_SPLITMV])
    107     {
    108         /* See if above-left MV can be merged with NEAREST */
    109         if (mv->as_int == near_mvs[CNT_NEAREST].as_int)
    110             cnt[CNT_NEAREST] += 1;
    111     }
    112 
    113     cnt[CNT_SPLITMV] = ((above->mbmi.mode == SPLITMV)
    114                         + (left->mbmi.mode == SPLITMV)) * 2
    115                        + (aboveleft->mbmi.mode == SPLITMV);
    116 
    117     /* Swap near and nearest if necessary */
    118     if (cnt[CNT_NEAR] > cnt[CNT_NEAREST])
    119     {
    120         int tmp;
    121         tmp = cnt[CNT_NEAREST];
    122         cnt[CNT_NEAREST] = cnt[CNT_NEAR];
    123         cnt[CNT_NEAR] = tmp;
    124         tmp = near_mvs[CNT_NEAREST].as_int;
    125         near_mvs[CNT_NEAREST].as_int = near_mvs[CNT_NEAR].as_int;
    126         near_mvs[CNT_NEAR].as_int = tmp;
    127     }
    128 
    129     /* Use near_mvs[0] to store the "best" MV */
    130     if (cnt[CNT_NEAREST] >= cnt[CNT_INTRA])
    131         near_mvs[CNT_INTRA] = near_mvs[CNT_NEAREST];
    132 
    133     /* Set up return values */
    134     *best_mv = near_mvs[0].as_mv;
    135     *nearest = near_mvs[CNT_NEAREST].as_mv;
    136     *nearby = near_mvs[CNT_NEAR].as_mv;
    137 
    138     vp8_clamp_mv(nearest, xd);
    139     vp8_clamp_mv(nearby, xd);
    140     vp8_clamp_mv(best_mv, xd); /*TODO: move this up before the copy*/
    141 }
    142 
    143 vp8_prob *vp8_mv_ref_probs(
    144     vp8_prob p[VP8_MVREFS-1], const int near_mv_ref_ct[4]
    145 )
    146 {
    147     p[0] = vp8_mode_contexts [near_mv_ref_ct[0]] [0];
    148     p[1] = vp8_mode_contexts [near_mv_ref_ct[1]] [1];
    149     p[2] = vp8_mode_contexts [near_mv_ref_ct[2]] [2];
    150     p[3] = vp8_mode_contexts [near_mv_ref_ct[3]] [3];
    151     /*p[3] = vp8_mode_contexts [near_mv_ref_ct[1] + near_mv_ref_ct[2] + near_mv_ref_ct[3]] [3];*/
    152     return p;
    153 }
    154 
    155 const B_MODE_INFO *vp8_left_bmi(const MODE_INFO *cur_mb, int b)
    156 {
    157     if (!(b & 3))
    158     {
    159         /* On L edge, get from MB to left of us */
    160         --cur_mb;
    161         b += 4;
    162     }
    163 
    164     return cur_mb->bmi + b - 1;
    165 }
    166 
    167 const B_MODE_INFO *vp8_above_bmi(const MODE_INFO *cur_mb, int b, int mi_stride)
    168 {
    169     if (!(b >> 2))
    170     {
    171         /* On top edge, get from MB above us */
    172         cur_mb -= mi_stride;
    173         b += 16;
    174     }
    175 
    176     return cur_mb->bmi + b - 4;
    177 }
    178