File: mcenc.c

package info (click to toggle)
libtheora 1.1.1+dfsg.1-15
  • links: PTS, VCS
  • area: main
  • in suites: buster, sid
  • size: 7,460 kB
  • sloc: ansic: 32,561; sh: 9,675; makefile: 744
file content (767 lines) | stat: -rw-r--r-- 28,552 bytes parent folder | download | duplicates (6)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009                *
 * by the Xiph.Org Foundation http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

  function:
  last mod: $Id$

 ********************************************************************/
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include "encint.h"



typedef struct oc_mcenc_ctx           oc_mcenc_ctx;



/*Temporary state used for motion estimation.*/
struct oc_mcenc_ctx{
  /*The candidate motion vectors.*/
  int                candidates[13][2];
  /*The start of the Set B candidates.*/
  int                setb0;
  /*The total number of candidates.*/
  int                ncandidates;
};



/*The maximum Y plane SAD value for accepting the median predictor.*/
#define OC_YSAD_THRESH1            (256)
/*The amount to right shift the minimum error by when inflating it for
   computing the second maximum Y plane SAD threshold.*/
#define OC_YSAD_THRESH2_SCALE_BITS (4)
/*The amount to add to the second maximum Y plane threshold when inflating
   it.*/
#define OC_YSAD_THRESH2_OFFSET     (64)

/*The vector offsets in the X direction for each search site in the square
   pattern.*/
static const int OC_SQUARE_DX[9]={-1,0,1,-1,0,1,-1,0,1};
/*The vector offsets in the Y direction for each search site in the square
   pattern.*/
static const int OC_SQUARE_DY[9]={-1,-1,-1,0,0,0,1,1,1};
/*The number of sites to search for each boundary condition in the square
   pattern.
  Bit flags for the boundary conditions are as follows:
  1: -16==dx
  2:      dx==15(.5)
  4: -16==dy
  8:      dy==15(.5)*/
static const int OC_SQUARE_NSITES[11]={8,5,5,0,5,3,3,0,5,3,3};
/*The list of sites to search for each boundary condition in the square
   pattern.*/
static const int OC_SQUARE_SITES[11][8]={
  /* -15.5<dx<31,       -15.5<dy<15(.5)*/
  {0,1,2,3,5,6,7,8},
  /*-15.5==dx,          -15.5<dy<15(.5)*/
  {1,2,5,7,8},
  /*     dx==15(.5),    -15.5<dy<15(.5)*/
  {0,1,3,6,7},
  /*-15.5==dx==15(.5),  -15.5<dy<15(.5)*/
  {-1},
  /* -15.5<dx<15(.5),  -15.5==dy*/
  {3,5,6,7,8},
  /*-15.5==dx,         -15.5==dy*/
  {5,7,8},
  /*     dx==15(.5),   -15.5==dy*/
  {3,6,7},
  /*-15.5==dx==15(.5), -15.5==dy*/
  {-1},
  /*-15.5dx<15(.5),           dy==15(.5)*/
  {0,1,2,3,5},
  /*-15.5==dx,                dy==15(.5)*/
  {1,2,5},
  /*       dx==15(.5),        dy==15(.5)*/
  {0,1,3}
};


static void oc_mcenc_find_candidates(oc_enc_ctx *_enc,oc_mcenc_ctx *_mcenc,
 int _accum[2],int _mbi,int _frame){
  oc_mb_enc_info *embs;
  int             a[3][2];
  int             ncandidates;
  unsigned        nmbi;
  int             i;
  embs=_enc->mb_info;
  /*Skip a position to store the median predictor in.*/
  ncandidates=1;
  if(embs[_mbi].ncneighbors>0){
    /*Fill in the first part of set A: the vectors from adjacent blocks.*/
    for(i=0;i<embs[_mbi].ncneighbors;i++){
      nmbi=embs[_mbi].cneighbors[i];
      _mcenc->candidates[ncandidates][0]=embs[nmbi].analysis_mv[0][_frame][0];
      _mcenc->candidates[ncandidates][1]=embs[nmbi].analysis_mv[0][_frame][1];
      ncandidates++;
    }
  }
  /*Add a few additional vectors to set A: the vectors used in the previous
     frames and the (0,0) vector.*/
  _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,_accum[0],31);
  _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,_accum[1],31);
  ncandidates++;
  _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,
   embs[_mbi].analysis_mv[1][_frame][0]+_accum[0],31);
  _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,
   embs[_mbi].analysis_mv[1][_frame][1]+_accum[1],31);
  ncandidates++;
  _mcenc->candidates[ncandidates][0]=0;
  _mcenc->candidates[ncandidates][1]=0;
  ncandidates++;
  /*Use the first three vectors of set A to find our best predictor: their
     median.*/
  memcpy(a,_mcenc->candidates+1,sizeof(a));
  OC_SORT2I(a[0][0],a[1][0]);
  OC_SORT2I(a[0][1],a[1][1]);
  OC_SORT2I(a[1][0],a[2][0]);
  OC_SORT2I(a[1][1],a[2][1]);
  OC_SORT2I(a[0][0],a[1][0]);
  OC_SORT2I(a[0][1],a[1][1]);
  _mcenc->candidates[0][0]=a[1][0];
  _mcenc->candidates[0][1]=a[1][1];
  /*Fill in set B: accelerated predictors for this and adjacent macro blocks.*/
  _mcenc->setb0=ncandidates;
  /*The first time through the loop use the current macro block.*/
  nmbi=_mbi;
  for(i=0;;i++){
    _mcenc->candidates[ncandidates][0]=OC_CLAMPI(-31,
     2*embs[_mbi].analysis_mv[1][_frame][0]
     -embs[_mbi].analysis_mv[2][_frame][0]+_accum[0],31);
    _mcenc->candidates[ncandidates][1]=OC_CLAMPI(-31,
     2*embs[_mbi].analysis_mv[1][_frame][1]
     -embs[_mbi].analysis_mv[2][_frame][1]+_accum[1],31);
    ncandidates++;
    if(i>=embs[_mbi].npneighbors)break;
    nmbi=embs[_mbi].pneighbors[i];
  }
  /*Truncate to full-pel positions.*/
  for(i=0;i<ncandidates;i++){
    _mcenc->candidates[i][0]=OC_DIV2(_mcenc->candidates[i][0]);
    _mcenc->candidates[i][1]=OC_DIV2(_mcenc->candidates[i][1]);
  }
  _mcenc->ncandidates=ncandidates;
}

#if 0
static unsigned oc_sad16_halfpel(const oc_enc_ctx *_enc,
 const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],
 int _mvoffset0,int _mvoffset1,const unsigned char *_src,
 const unsigned char *_ref,int _ystride,unsigned _best_err){
  unsigned err;
  int      bi;
  err=0;
  for(bi=0;bi<4;bi++){
    ptrdiff_t frag_offs;
    frag_offs=_frag_buf_offs[_fragis[bi]];
    err+=oc_enc_frag_sad2_thresh(_enc,_src+frag_offs,_ref+frag_offs+_mvoffset0,
     _ref+frag_offs+_mvoffset1,_ystride,_best_err-err);
  }
  return err;
}
#endif

static unsigned oc_satd16_halfpel(const oc_enc_ctx *_enc,
 const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],
 int _mvoffset0,int _mvoffset1,const unsigned char *_src,
 const unsigned char *_ref,int _ystride,unsigned _best_err){
  unsigned err;
  int      bi;
  err=0;
  for(bi=0;bi<4;bi++){
    ptrdiff_t frag_offs;
    frag_offs=_frag_buf_offs[_fragis[bi]];
    err+=oc_enc_frag_satd2_thresh(_enc,_src+frag_offs,_ref+frag_offs+_mvoffset0,
     _ref+frag_offs+_mvoffset1,_ystride,_best_err-err);
  }
  return err;
}

static unsigned oc_mcenc_ysad_check_mbcandidate_fullpel(const oc_enc_ctx *_enc,
 const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],int _dx,int _dy,
 const unsigned char *_src,const unsigned char *_ref,int _ystride,
 unsigned _block_err[4]){
  unsigned err;
  int      mvoffset;
  int      bi;
  mvoffset=_dx+_dy*_ystride;
  err=0;
  for(bi=0;bi<4;bi++){
    ptrdiff_t frag_offs;
    unsigned  block_err;
    frag_offs=_frag_buf_offs[_fragis[bi]];
    block_err=oc_enc_frag_sad(_enc,
     _src+frag_offs,_ref+frag_offs+mvoffset,_ystride);
    _block_err[bi]=block_err;
    err+=block_err;
  }
  return err;
}

static int oc_mcenc_ysatd_check_mbcandidate_fullpel(const oc_enc_ctx *_enc,
 const ptrdiff_t *_frag_buf_offs,const ptrdiff_t _fragis[4],int _dx,int _dy,
 const unsigned char *_src,const unsigned char *_ref,int _ystride){
  int mvoffset;
  int err;
  int bi;
  mvoffset=_dx+_dy*_ystride;
  err=0;
  for(bi=0;bi<4;bi++){
    ptrdiff_t frag_offs;
    frag_offs=_frag_buf_offs[_fragis[bi]];
    err+=oc_enc_frag_satd_thresh(_enc,
     _src+frag_offs,_ref+frag_offs+mvoffset,_ystride,UINT_MAX);
  }
  return err;
}

static unsigned oc_mcenc_ysatd_check_bcandidate_fullpel(const oc_enc_ctx *_enc,
 ptrdiff_t _frag_offs,int _dx,int _dy,
 const unsigned char *_src,const unsigned char *_ref,int _ystride){
  return oc_enc_frag_satd_thresh(_enc,
   _src+_frag_offs,_ref+_frag_offs+_dx+_dy*_ystride,_ystride,UINT_MAX);
}

/*Perform a motion vector search for this macro block against a single
   reference frame.
  As a bonus, individual block motion vectors are computed as well, as much of
   the work can be shared.
  The actual motion vector is stored in the appropriate place in the
   oc_mb_enc_info structure.
  _mcenc:    The motion compensation context.
  _accum:    Drop frame/golden MV accumulators.
  _mbi:      The macro block index.
  _frame:    The frame to search, either OC_FRAME_PREV or OC_FRAME_GOLD.*/
void oc_mcenc_search_frame(oc_enc_ctx *_enc,int _accum[2],int _mbi,int _frame){
  /*Note: Traditionally this search is done using a rate-distortion objective
     function of the form D+lambda*R.
    However, xiphmont tested this and found it produced a small degredation,
     while requiring extra computation.
    This is most likely due to Theora's peculiar MV encoding scheme: MVs are
     not coded relative to a predictor, and the only truly cheap way to use a
     MV is in the LAST or LAST2 MB modes, which are not being considered here.
    Therefore if we use the MV found here, it's only because both LAST and
     LAST2 performed poorly, and therefore the MB is not likely to be uniform
     or suffer from the aperture problem.
    Furthermore we would like to re-use the MV found here for as many MBs as
     possible, so picking a slightly sub-optimal vector to save a bit or two
     may cause increased degredation in many blocks to come.
    We could artificially reduce lambda to compensate, but it's faster to just
     disable it entirely, and use D (the distortion) as the sole criterion.*/
  oc_mcenc_ctx         mcenc;
  const ptrdiff_t     *frag_buf_offs;
  const ptrdiff_t     *fragis;
  const unsigned char *src;
  const unsigned char *ref;
  int                  ystride;
  oc_mb_enc_info      *embs;
  ogg_int32_t          hit_cache[31];
  ogg_int32_t          hitbit;
  unsigned             best_block_err[4];
  unsigned             block_err[4];
  unsigned             best_err;
  int                  best_vec[2];
  int                  best_block_vec[4][2];
  int                  candx;
  int                  candy;
  int                  bi;
  embs=_enc->mb_info;
  /*Find some candidate motion vectors.*/
  oc_mcenc_find_candidates(_enc,&mcenc,_accum,_mbi,_frame);
  /*Clear the cache of locations we've examined.*/
  memset(hit_cache,0,sizeof(hit_cache));
  /*Start with the median predictor.*/
  candx=mcenc.candidates[0][0];
  candy=mcenc.candidates[0][1];
  hit_cache[candy+15]|=(ogg_int32_t)1<<candx+15;
  frag_buf_offs=_enc->state.frag_buf_offs;
  fragis=_enc->state.mb_maps[_mbi][0];
  src=_enc->state.ref_frame_data[OC_FRAME_IO];
  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_frame]];
  ystride=_enc->state.ref_ystride[0];
  /*TODO: customize error function for speed/(quality+size) tradeoff.*/
  best_err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
   frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
  best_vec[0]=candx;
  best_vec[1]=candy;
  if(_frame==OC_FRAME_PREV){
    for(bi=0;bi<4;bi++){
      best_block_err[bi]=block_err[bi];
      best_block_vec[bi][0]=candx;
      best_block_vec[bi][1]=candy;
    }
  }
  /*If this predictor fails, move on to set A.*/
  if(best_err>OC_YSAD_THRESH1){
    unsigned err;
    unsigned t2;
    int      ncs;
    int      ci;
    /*Compute the early termination threshold for set A.*/
    t2=embs[_mbi].error[_frame];
    ncs=OC_MINI(3,embs[_mbi].ncneighbors);
    for(ci=0;ci<ncs;ci++){
      t2=OC_MAXI(t2,embs[embs[_mbi].cneighbors[ci]].error[_frame]);
    }
    t2+=(t2>>OC_YSAD_THRESH2_SCALE_BITS)+OC_YSAD_THRESH2_OFFSET;
    /*Examine the candidates in set A.*/
    for(ci=1;ci<mcenc.setb0;ci++){
      candx=mcenc.candidates[ci][0];
      candy=mcenc.candidates[ci][1];
      /*If we've already examined this vector, then we would be using it if it
         was better than what we are using.*/
      hitbit=(ogg_int32_t)1<<candx+15;
      if(hit_cache[candy+15]&hitbit)continue;
      hit_cache[candy+15]|=hitbit;
      err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
       frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
      if(err<best_err){
        best_err=err;
        best_vec[0]=candx;
        best_vec[1]=candy;
      }
      if(_frame==OC_FRAME_PREV){
        for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
          best_block_err[bi]=block_err[bi];
          best_block_vec[bi][0]=candx;
          best_block_vec[bi][1]=candy;
        }
      }
    }
    if(best_err>t2){
      /*Examine the candidates in set B.*/
      for(;ci<mcenc.ncandidates;ci++){
        candx=mcenc.candidates[ci][0];
        candy=mcenc.candidates[ci][1];
        hitbit=(ogg_int32_t)1<<candx+15;
        if(hit_cache[candy+15]&hitbit)continue;
        hit_cache[candy+15]|=hitbit;
        err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
         frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
        if(err<best_err){
          best_err=err;
          best_vec[0]=candx;
          best_vec[1]=candy;
        }
        if(_frame==OC_FRAME_PREV){
          for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
            best_block_err[bi]=block_err[bi];
            best_block_vec[bi][0]=candx;
            best_block_vec[bi][1]=candy;
          }
        }
      }
      /*Use the same threshold for set B as in set A.*/
      if(best_err>t2){
        int best_site;
        int nsites;
        int sitei;
        int site;
        int b;
        /*Square pattern search.*/
        for(;;){
          best_site=4;
          /*Compose the bit flags for boundary conditions.*/
          b=OC_DIV16(-best_vec[0]+1)|OC_DIV16(best_vec[0]+1)<<1|
           OC_DIV16(-best_vec[1]+1)<<2|OC_DIV16(best_vec[1]+1)<<3;
          nsites=OC_SQUARE_NSITES[b];
          for(sitei=0;sitei<nsites;sitei++){
            site=OC_SQUARE_SITES[b][sitei];
            candx=best_vec[0]+OC_SQUARE_DX[site];
            candy=best_vec[1]+OC_SQUARE_DY[site];
            hitbit=(ogg_int32_t)1<<candx+15;
            if(hit_cache[candy+15]&hitbit)continue;
            hit_cache[candy+15]|=hitbit;
            err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
             frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
            if(err<best_err){
              best_err=err;
              best_site=site;
            }
            if(_frame==OC_FRAME_PREV){
              for(bi=0;bi<4;bi++)if(block_err[bi]<best_block_err[bi]){
                best_block_err[bi]=block_err[bi];
                best_block_vec[bi][0]=candx;
                best_block_vec[bi][1]=candy;
              }
            }
          }
          if(best_site==4)break;
          best_vec[0]+=OC_SQUARE_DX[best_site];
          best_vec[1]+=OC_SQUARE_DY[best_site];
        }
        /*Final 4-MV search.*/
        /*Simply use 1/4 of the macro block set A and B threshold as the
           individual block threshold.*/
        if(_frame==OC_FRAME_PREV){
          t2>>=2;
          for(bi=0;bi<4;bi++){
            if(best_block_err[bi]>t2){
              /*Square pattern search.
                We do this in a slightly interesting manner.
                We continue to check the SAD of all four blocks in the
                 macro block.
                This gives us two things:
                 1) We can continue to use the hit_cache to avoid duplicate
                     checks.
                    Otherwise we could continue to read it, but not write to it
                     without saving and restoring it for each block.
                    Note that we could still eliminate a large number of
                     duplicate checks by taking into account the site we came
                     from when choosing the site list.
                    We can still do that to avoid extra hit_cache queries, and
                     it might even be a speed win.
                 2) It gives us a slightly better chance of escaping local
                     minima.
                    We would not be here if we weren't doing a fairly bad job
                     in finding a good vector, and checking these vectors can
                     save us from 100 to several thousand points off our SAD 1
                     in 15 times.
                TODO: Is this a good idea?
                Who knows.
                It needs more testing.*/
              for(;;){
                int bestx;
                int besty;
                int bj;
                bestx=best_block_vec[bi][0];
                besty=best_block_vec[bi][1];
                /*Compose the bit flags for boundary conditions.*/
                b=OC_DIV16(-bestx+1)|OC_DIV16(bestx+1)<<1|
                 OC_DIV16(-besty+1)<<2|OC_DIV16(besty+1)<<3;
                nsites=OC_SQUARE_NSITES[b];
                for(sitei=0;sitei<nsites;sitei++){
                  site=OC_SQUARE_SITES[b][sitei];
                  candx=bestx+OC_SQUARE_DX[site];
                  candy=besty+OC_SQUARE_DY[site];
                  hitbit=(ogg_int32_t)1<<candx+15;
                  if(hit_cache[candy+15]&hitbit)continue;
                  hit_cache[candy+15]|=hitbit;
                  err=oc_mcenc_ysad_check_mbcandidate_fullpel(_enc,
                   frag_buf_offs,fragis,candx,candy,src,ref,ystride,block_err);
                  if(err<best_err){
                    best_err=err;
                    best_vec[0]=candx;
                    best_vec[1]=candy;
                  }
                  for(bj=0;bj<4;bj++)if(block_err[bj]<best_block_err[bj]){
                    best_block_err[bj]=block_err[bj];
                    best_block_vec[bj][0]=candx;
                    best_block_vec[bj][1]=candy;
                  }
                }
                if(best_block_vec[bi][0]==bestx&&best_block_vec[bi][1]==besty){
                  break;
                }
              }
            }
          }
        }
      }
    }
  }
  embs[_mbi].error[_frame]=(ogg_uint16_t)best_err;
  candx=best_vec[0];
  candy=best_vec[1];
  embs[_mbi].satd[_frame]=oc_mcenc_ysatd_check_mbcandidate_fullpel(_enc,
   frag_buf_offs,fragis,candx,candy,src,ref,ystride);
  embs[_mbi].analysis_mv[0][_frame][0]=(signed char)(candx<<1);
  embs[_mbi].analysis_mv[0][_frame][1]=(signed char)(candy<<1);
  if(_frame==OC_FRAME_PREV){
    for(bi=0;bi<4;bi++){
      candx=best_block_vec[bi][0];
      candy=best_block_vec[bi][1];
      embs[_mbi].block_satd[bi]=oc_mcenc_ysatd_check_bcandidate_fullpel(_enc,
       frag_buf_offs[fragis[bi]],candx,candy,src,ref,ystride);
      embs[_mbi].block_mv[bi][0]=(signed char)(candx<<1);
      embs[_mbi].block_mv[bi][1]=(signed char)(candy<<1);
    }
  }
}

void oc_mcenc_search(oc_enc_ctx *_enc,int _mbi){
  oc_mv2         *mvs;
  int             accum_p[2];
  int             accum_g[2];
  mvs=_enc->mb_info[_mbi].analysis_mv;
  if(_enc->prevframe_dropped){
    accum_p[0]=mvs[0][OC_FRAME_PREV][0];
    accum_p[1]=mvs[0][OC_FRAME_PREV][1];
  }
  else accum_p[1]=accum_p[0]=0;
  accum_g[0]=mvs[2][OC_FRAME_GOLD][0];
  accum_g[1]=mvs[2][OC_FRAME_GOLD][1];
  mvs[0][OC_FRAME_PREV][0]-=mvs[2][OC_FRAME_PREV][0];
  mvs[0][OC_FRAME_PREV][1]-=mvs[2][OC_FRAME_PREV][1];
  /*Move the motion vector predictors back a frame.*/
  memmove(mvs+1,mvs,2*sizeof(*mvs));
  /*Search the last frame.*/
  oc_mcenc_search_frame(_enc,accum_p,_mbi,OC_FRAME_PREV);
  mvs[2][OC_FRAME_PREV][0]=accum_p[0];
  mvs[2][OC_FRAME_PREV][1]=accum_p[1];
  /*GOLDEN MVs are different from PREV MVs in that they're each absolute
     offsets from some frame in the past rather than relative offsets from the
     frame before.
    For predictor calculation to make sense, we need them to be in the same
     form as PREV MVs.*/
  mvs[1][OC_FRAME_GOLD][0]-=mvs[2][OC_FRAME_GOLD][0];
  mvs[1][OC_FRAME_GOLD][1]-=mvs[2][OC_FRAME_GOLD][1];
  mvs[2][OC_FRAME_GOLD][0]-=accum_g[0];
  mvs[2][OC_FRAME_GOLD][1]-=accum_g[1];
  /*Search the golden frame.*/
  oc_mcenc_search_frame(_enc,accum_g,_mbi,OC_FRAME_GOLD);
  /*Put GOLDEN MVs back into absolute offset form.
    The newest MV is already an absolute offset.*/
  mvs[2][OC_FRAME_GOLD][0]+=accum_g[0];
  mvs[2][OC_FRAME_GOLD][1]+=accum_g[1];
  mvs[1][OC_FRAME_GOLD][0]+=mvs[2][OC_FRAME_GOLD][0];
  mvs[1][OC_FRAME_GOLD][1]+=mvs[2][OC_FRAME_GOLD][1];
}

#if 0
static int oc_mcenc_ysad_halfpel_mbrefine(const oc_enc_ctx *_enc,int _mbi,
 int _vec[2],int _best_err,int _frame){
  const unsigned char *src;
  const unsigned char *ref;
  const ptrdiff_t     *frag_buf_offs;
  const ptrdiff_t     *fragis;
  int                  offset_y[9];
  int                  ystride;
  int                  mvoffset_base;
  int                  best_site;
  int                  sitei;
  int                  err;
  src=_enc->state.ref_frame_data[OC_FRAME_IO];
  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_framei]];
  frag_buf_offs=_enc->state.frag_buf_offs;
  fragis=_enc->state.mb_maps[_mbi][0];
  ystride=_enc->state.ref_ystride[0];
  mvoffset_base=_vec[0]+_vec[1]*ystride;
  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
  offset_y[3]=offset_y[5]=0;
  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
  best_site=4;
  for(sitei=0;sitei<8;sitei++){
    int site;
    int xmask;
    int ymask;
    int dx;
    int dy;
    int mvoffset0;
    int mvoffset1;
    site=OC_SQUARE_SITES[0][sitei];
    dx=OC_SQUARE_DX[site];
    dy=OC_SQUARE_DY[site];
    /*The following code SHOULD be equivalent to
        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
      However, it should also be much faster, as it involves no multiplies and
       doesn't have to handle chroma vectors.*/
    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
    mvoffset0=mvoffset_base+(dx&xmask)+(offset_y[site]&ymask);
    mvoffset1=mvoffset_base+(dx&~xmask)+(offset_y[site]&~ymask);
    err=oc_sad16_halfpel(_enc,frag_buf_offs,fragis,
     mvoffset0,mvoffset1,src,ref,ystride,_best_err);
    if(err<_best_err){
      _best_err=err;
      best_site=site;
    }
  }
  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
  return _best_err;
}
#endif

static unsigned oc_mcenc_ysatd_halfpel_mbrefine(const oc_enc_ctx *_enc,
 int _mbi,int _vec[2],unsigned _best_err,int _frame){
  const unsigned char *src;
  const unsigned char *ref;
  const ptrdiff_t     *frag_buf_offs;
  const ptrdiff_t     *fragis;
  int                  offset_y[9];
  int                  ystride;
  int                  mvoffset_base;
  int                  best_site;
  int                  sitei;
  int                  err;
  src=_enc->state.ref_frame_data[OC_FRAME_IO];
  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[_frame]];
  frag_buf_offs=_enc->state.frag_buf_offs;
  fragis=_enc->state.mb_maps[_mbi][0];
  ystride=_enc->state.ref_ystride[0];
  mvoffset_base=_vec[0]+_vec[1]*ystride;
  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
  offset_y[3]=offset_y[5]=0;
  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
  best_site=4;
  for(sitei=0;sitei<8;sitei++){
    int site;
    int xmask;
    int ymask;
    int dx;
    int dy;
    int mvoffset0;
    int mvoffset1;
    site=OC_SQUARE_SITES[0][sitei];
    dx=OC_SQUARE_DX[site];
    dy=OC_SQUARE_DY[site];
    /*The following code SHOULD be equivalent to
        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
      However, it should also be much faster, as it involves no multiplies and
       doesn't have to handle chroma vectors.*/
    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
    mvoffset0=mvoffset_base+(dx&xmask)+(offset_y[site]&ymask);
    mvoffset1=mvoffset_base+(dx&~xmask)+(offset_y[site]&~ymask);
    err=oc_satd16_halfpel(_enc,frag_buf_offs,fragis,
     mvoffset0,mvoffset1,src,ref,ystride,_best_err);
    if(err<_best_err){
      _best_err=err;
      best_site=site;
    }
  }
  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
  return _best_err;
}

void oc_mcenc_refine1mv(oc_enc_ctx *_enc,int _mbi,int _frame){
  oc_mb_enc_info *embs;
  int             vec[2];
  embs=_enc->mb_info;
  vec[0]=OC_DIV2(embs[_mbi].analysis_mv[0][_frame][0]);
  vec[1]=OC_DIV2(embs[_mbi].analysis_mv[0][_frame][1]);
  embs[_mbi].satd[_frame]=oc_mcenc_ysatd_halfpel_mbrefine(_enc,
   _mbi,vec,embs[_mbi].satd[_frame],_frame);
  embs[_mbi].analysis_mv[0][_frame][0]=(signed char)vec[0];
  embs[_mbi].analysis_mv[0][_frame][1]=(signed char)vec[1];
}

#if 0
static int oc_mcenc_ysad_halfpel_brefine(const oc_enc_ctx *_enc,
 int _vec[2],const unsigned char *_src,const unsigned char *_ref,int _ystride,
 int _offset_y[9],unsigned _best_err){
  int mvoffset_base;
  int best_site;
  int sitei;
  mvoffset_base=_vec[0]+_vec[1]*_ystride;
  best_site=4;
  for(sitei=0;sitei<8;sitei++){
    unsigned err;
    int      site;
    int      xmask;
    int      ymask;
    int      dx;
    int      dy;
    int      mvoffset0;
    int      mvoffset1;
    site=OC_SQUARE_SITES[0][sitei];
    dx=OC_SQUARE_DX[site];
    dy=OC_SQUARE_DY[site];
    /*The following code SHOULD be equivalent to
        oc_state_get_mv_offsets(&_mcenc->enc.state,&mvoffset0,&mvoffset1,
         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy,ref_ystride,0);
      However, it should also be much faster, as it involves no multiplies and
       doesn't have to handle chroma vectors.*/
    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
    mvoffset0=mvoffset_base+(dx&xmask)+(_offset_y[site]&ymask);
    mvoffset1=mvoffset_base+(dx&~xmask)+(_offset_y[site]&~ymask);
    err=oc_enc_frag_sad2_thresh(_enc,_src,
     _ref+mvoffset0,_ref+mvoffset1,ystride,_best_err);
    if(err<_best_err){
      _best_err=err;
      best_site=site;
    }
  }
  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
  return _best_err;
}
#endif

static unsigned oc_mcenc_ysatd_halfpel_brefine(const oc_enc_ctx *_enc,
 int _vec[2],const unsigned char *_src,const unsigned char *_ref,int _ystride,
 int _offset_y[9],unsigned _best_err){
  int mvoffset_base;
  int best_site;
  int sitei;
  mvoffset_base=_vec[0]+_vec[1]*_ystride;
  best_site=4;
  for(sitei=0;sitei<8;sitei++){
    unsigned err;
    int      site;
    int      xmask;
    int      ymask;
    int      dx;
    int      dy;
    int      mvoffset0;
    int      mvoffset1;
    site=OC_SQUARE_SITES[0][sitei];
    dx=OC_SQUARE_DX[site];
    dy=OC_SQUARE_DY[site];
    /*The following code SHOULD be equivalent to
        oc_state_get_mv_offsets(&_enc->state,&mvoffsets,0,
         (_vec[0]<<1)+dx,(_vec[1]<<1)+dy);
      However, it should also be much faster, as it involves no multiplies and
       doesn't have to handle chroma vectors.*/
    xmask=OC_SIGNMASK(((_vec[0]<<1)+dx)^dx);
    ymask=OC_SIGNMASK(((_vec[1]<<1)+dy)^dy);
    mvoffset0=mvoffset_base+(dx&xmask)+(_offset_y[site]&ymask);
    mvoffset1=mvoffset_base+(dx&~xmask)+(_offset_y[site]&~ymask);
    err=oc_enc_frag_satd2_thresh(_enc,_src,
     _ref+mvoffset0,_ref+mvoffset1,_ystride,_best_err);
    if(err<_best_err){
      _best_err=err;
      best_site=site;
    }
  }
  _vec[0]=(_vec[0]<<1)+OC_SQUARE_DX[best_site];
  _vec[1]=(_vec[1]<<1)+OC_SQUARE_DY[best_site];
  return _best_err;
}

void oc_mcenc_refine4mv(oc_enc_ctx *_enc,int _mbi){
  oc_mb_enc_info      *embs;
  const ptrdiff_t     *frag_buf_offs;
  const ptrdiff_t     *fragis;
  const unsigned char *src;
  const unsigned char *ref;
  int                  offset_y[9];
  int                  ystride;
  int                  bi;
  ystride=_enc->state.ref_ystride[0];
  frag_buf_offs=_enc->state.frag_buf_offs;
  fragis=_enc->state.mb_maps[_mbi][0];
  src=_enc->state.ref_frame_data[OC_FRAME_IO];
  ref=_enc->state.ref_frame_data[_enc->state.ref_frame_idx[OC_FRAME_PREV]];
  offset_y[0]=offset_y[1]=offset_y[2]=-ystride;
  offset_y[3]=offset_y[5]=0;
  offset_y[6]=offset_y[7]=offset_y[8]=ystride;
  embs=_enc->mb_info;
  for(bi=0;bi<4;bi++){
    ptrdiff_t frag_offs;
    int       vec[2];
    frag_offs=frag_buf_offs[fragis[bi]];
    vec[0]=OC_DIV2(embs[_mbi].block_mv[bi][0]);
    vec[1]=OC_DIV2(embs[_mbi].block_mv[bi][1]);
    embs[_mbi].block_satd[bi]=oc_mcenc_ysatd_halfpel_brefine(_enc,vec,
     src+frag_offs,ref+frag_offs,ystride,offset_y,embs[_mbi].block_satd[bi]);
    embs[_mbi].ref_mv[bi][0]=(signed char)vec[0];
    embs[_mbi].ref_mv[bi][1]=(signed char)vec[1];
  }
}