summaryrefslogtreecommitdiff
path: root/libavcodec/svq1dec.c
blob: 174313179c598f45985fe1bb66dae3cdcf01881a (plain)
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
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
/*
 * SVQ1 decoder
 * ported to MPlayer by Arpi <arpi@thot.banki.hu>
 * ported to libavcodec by Nick Kurshev <nickols_k@mail.ru>
 *
 * Copyright (C) 2002 the xine project
 * Copyright (C) 2002 the ffmpeg project
 *
 * SVQ1 Encoder (c) 2004 Mike Melanson <melanson@pcisys.net>
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Sorenson Vector Quantizer #1 (SVQ1) video codec.
 * For more information of the SVQ1 algorithm, visit:
 *   http://www.pcisys.net/~melanson/codecs/
 */


#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"
#include "mathops.h"

#include "svq1.h"

#undef NDEBUG
#include <assert.h>

extern const uint8_t ff_mvtab[33][2];

static VLC svq1_block_type;
static VLC svq1_motion_component;
static VLC svq1_intra_multistage[6];
static VLC svq1_inter_multistage[6];
static VLC svq1_intra_mean;
static VLC svq1_inter_mean;

/* motion vector (prediction) */
typedef struct svq1_pmv_s {
  int           x;
  int           y;
} svq1_pmv;

static const uint16_t checksum_table[256] = {
  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
  0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
  0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
  0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
  0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
  0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
  0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
  0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
  0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
  0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
  0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
  0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
  0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
  0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
  0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
  0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
  0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
  0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
  0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
  0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
  0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
  0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
  0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
  0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
  0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
  0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
  0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
  0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
  0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
  0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
  0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
  0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};

static const uint8_t string_table[256] = {
  0x00, 0xD5, 0x7F, 0xAA, 0xFE, 0x2B, 0x81, 0x54,
  0x29, 0xFC, 0x56, 0x83, 0xD7, 0x02, 0xA8, 0x7D,
  0x52, 0x87, 0x2D, 0xF8, 0xAC, 0x79, 0xD3, 0x06,
  0x7B, 0xAE, 0x04, 0xD1, 0x85, 0x50, 0xFA, 0x2F,
  0xA4, 0x71, 0xDB, 0x0E, 0x5A, 0x8F, 0x25, 0xF0,
  0x8D, 0x58, 0xF2, 0x27, 0x73, 0xA6, 0x0C, 0xD9,
  0xF6, 0x23, 0x89, 0x5C, 0x08, 0xDD, 0x77, 0xA2,
  0xDF, 0x0A, 0xA0, 0x75, 0x21, 0xF4, 0x5E, 0x8B,
  0x9D, 0x48, 0xE2, 0x37, 0x63, 0xB6, 0x1C, 0xC9,
  0xB4, 0x61, 0xCB, 0x1E, 0x4A, 0x9F, 0x35, 0xE0,
  0xCF, 0x1A, 0xB0, 0x65, 0x31, 0xE4, 0x4E, 0x9B,
  0xE6, 0x33, 0x99, 0x4C, 0x18, 0xCD, 0x67, 0xB2,
  0x39, 0xEC, 0x46, 0x93, 0xC7, 0x12, 0xB8, 0x6D,
  0x10, 0xC5, 0x6F, 0xBA, 0xEE, 0x3B, 0x91, 0x44,
  0x6B, 0xBE, 0x14, 0xC1, 0x95, 0x40, 0xEA, 0x3F,
  0x42, 0x97, 0x3D, 0xE8, 0xBC, 0x69, 0xC3, 0x16,
  0xEF, 0x3A, 0x90, 0x45, 0x11, 0xC4, 0x6E, 0xBB,
  0xC6, 0x13, 0xB9, 0x6C, 0x38, 0xED, 0x47, 0x92,
  0xBD, 0x68, 0xC2, 0x17, 0x43, 0x96, 0x3C, 0xE9,
  0x94, 0x41, 0xEB, 0x3E, 0x6A, 0xBF, 0x15, 0xC0,
  0x4B, 0x9E, 0x34, 0xE1, 0xB5, 0x60, 0xCA, 0x1F,
  0x62, 0xB7, 0x1D, 0xC8, 0x9C, 0x49, 0xE3, 0x36,
  0x19, 0xCC, 0x66, 0xB3, 0xE7, 0x32, 0x98, 0x4D,
  0x30, 0xE5, 0x4F, 0x9A, 0xCE, 0x1B, 0xB1, 0x64,
  0x72, 0xA7, 0x0D, 0xD8, 0x8C, 0x59, 0xF3, 0x26,
  0x5B, 0x8E, 0x24, 0xF1, 0xA5, 0x70, 0xDA, 0x0F,
  0x20, 0xF5, 0x5F, 0x8A, 0xDE, 0x0B, 0xA1, 0x74,
  0x09, 0xDC, 0x76, 0xA3, 0xF7, 0x22, 0x88, 0x5D,
  0xD6, 0x03, 0xA9, 0x7C, 0x28, 0xFD, 0x57, 0x82,
  0xFF, 0x2A, 0x80, 0x55, 0x01, 0xD4, 0x7E, 0xAB,
  0x84, 0x51, 0xFB, 0x2E, 0x7A, 0xAF, 0x05, 0xD0,
  0xAD, 0x78, 0xD2, 0x07, 0x53, 0x86, 0x2C, 0xF9
};

#define SVQ1_PROCESS_VECTOR()\
    for (; level > 0; i++) {\
      /* process next depth */\
      if (i == m) {\
        m = n;\
        if (--level == 0)\
          break;\
      }\
      /* divide block if next bit set */\
      if (get_bits1 (bitbuf) == 0)\
        break;\
      /* add child nodes */\
      list[n++] = list[i];\
      list[n++] = list[i] + (((level & 1) ? pitch : 1) << ((level / 2) + 1));\
    }

#define SVQ1_ADD_CODEBOOK()\
          /* add codebook entries to vector */\
          for (j=0; j < stages; j++) {\
            n3  = codebook[entries[j]] ^ 0x80808080;\
            n1 += ((n3 & 0xFF00FF00) >> 8);\
            n2 +=  (n3 & 0x00FF00FF);\
          }\
\
          /* clip to [0..255] */\
          if (n1 & 0xFF00FF00) {\
            n3  = ((( n1 >> 15) & 0x00010001) | 0x01000100) - 0x00010001;\
            n1 += 0x7F007F00;\
            n1 |= (((~n1 >> 15) & 0x00010001) | 0x01000100) - 0x00010001;\
            n1 &= (n3 & 0x00FF00FF);\
          }\
\
          if (n2 & 0xFF00FF00) {\
            n3  = ((( n2 >> 15) & 0x00010001) | 0x01000100) - 0x00010001;\
            n2 += 0x7F007F00;\
            n2 |= (((~n2 >> 15) & 0x00010001) | 0x01000100) - 0x00010001;\
            n2 &= (n3 & 0x00FF00FF);\
          }

#define SVQ1_DO_CODEBOOK_INTRA()\
      for (y=0; y < height; y++) {\
        for (x=0; x < (width / 4); x++, codebook++) {\
        n1 = n4;\
        n2 = n4;\
        SVQ1_ADD_CODEBOOK()\
        /* store result */\
        dst[x] = (n1 << 8) | n2;\
        }\
        dst += (pitch / 4);\
      }

#define SVQ1_DO_CODEBOOK_NONINTRA()\
      for (y=0; y < height; y++) {\
        for (x=0; x < (width / 4); x++, codebook++) {\
        n3 = dst[x];\
        /* add mean value to vector */\
        n1 = ((n3 & 0xFF00FF00) >> 8) + n4;\
        n2 =  (n3 & 0x00FF00FF)          + n4;\
        SVQ1_ADD_CODEBOOK()\
        /* store result */\
        dst[x] = (n1 << 8) | n2;\
        }\
        dst += (pitch / 4);\
      }

#define SVQ1_CALC_CODEBOOK_ENTRIES(cbook)\
      codebook = (const uint32_t *) cbook[level];\
      if (stages > 0)\
        bit_cache = get_bits (bitbuf, 4*stages);\
      /* calculate codebook entries for this vector */\
      for (j=0; j < stages; j++) {\
        entries[j] = (((bit_cache >> (4*(stages - j - 1))) & 0xF) + 16*j) << (level + 1);\
      }\
      mean -= (stages * 128);\
      n4    = ((mean + (mean >> 31)) << 16) | (mean & 0xFFFF);

static int svq1_decode_block_intra (GetBitContext *bitbuf, uint8_t *pixels, int pitch ) {
  uint32_t    bit_cache;
  uint8_t    *list[63];
  uint32_t   *dst;
  const uint32_t *codebook;
  int         entries[6];
  int         i, j, m, n;
  int         mean, stages;
  unsigned    x, y, width, height, level;
  uint32_t    n1, n2, n3, n4;

  /* initialize list for breadth first processing of vectors */
  list[0] = pixels;

  /* recursively process vector */
  for (i=0, m=1, n=1, level=5; i < n; i++) {
    SVQ1_PROCESS_VECTOR();

    /* destination address and vector size */
    dst = (uint32_t *) list[i];
    width = 1 << ((4 + level) /2);
    height = 1 << ((3 + level) /2);

    /* get number of stages (-1 skips vector, 0 for mean only) */
    stages = get_vlc2(bitbuf, svq1_intra_multistage[level].table, 3, 3) - 1;

    if (stages == -1) {
        for (y=0; y < height; y++) {
          memset (&dst[y*(pitch / 4)], 0, width);
        }
      continue;                 /* skip vector */
    }

    if ((stages > 0) && (level >= 4)) {
      av_dlog(NULL,
              "Error (svq1_decode_block_intra): invalid vector: stages=%i level=%i\n",
              stages, level);
      return -1;        /* invalid vector */
    }

    mean = get_vlc2(bitbuf, svq1_intra_mean.table, 8, 3);

    if (stages == 0) {
      for (y=0; y < height; y++) {
        memset (&dst[y*(pitch / 4)], mean, width);
      }
    } else {
      SVQ1_CALC_CODEBOOK_ENTRIES(ff_svq1_intra_codebooks);
      SVQ1_DO_CODEBOOK_INTRA()
    }
  }

  return 0;
}

static int svq1_decode_block_non_intra (GetBitContext *bitbuf, uint8_t *pixels, int pitch ) {
  uint32_t    bit_cache;
  uint8_t    *list[63];
  uint32_t   *dst;
  const uint32_t *codebook;
  int         entries[6];
  int         i, j, m, n;
  int         mean, stages;
  int         x, y, width, height, level;
  uint32_t    n1, n2, n3, n4;

  /* initialize list for breadth first processing of vectors */
  list[0] = pixels;

  /* recursively process vector */
  for (i=0, m=1, n=1, level=5; i < n; i++) {
    SVQ1_PROCESS_VECTOR();

    /* destination address and vector size */
    dst = (uint32_t *) list[i];
    width = 1 << ((4 + level) /2);
    height = 1 << ((3 + level) /2);

    /* get number of stages (-1 skips vector, 0 for mean only) */
    stages = get_vlc2(bitbuf, svq1_inter_multistage[level].table, 3, 2) - 1;

    if (stages == -1) continue; /* skip vector */

    if ((stages > 0) && (level >= 4)) {
      av_dlog(NULL,
              "Error (svq1_decode_block_non_intra): invalid vector: stages=%i level=%i\n",
              stages, level);
      return -1;        /* invalid vector */
    }

    mean = get_vlc2(bitbuf, svq1_inter_mean.table, 9, 3) - 256;

    SVQ1_CALC_CODEBOOK_ENTRIES(ff_svq1_inter_codebooks);
    SVQ1_DO_CODEBOOK_NONINTRA()
  }
  return 0;
}

static int svq1_decode_motion_vector (GetBitContext *bitbuf, svq1_pmv *mv, svq1_pmv **pmv) {
  int        diff;
  int        i;

  for (i=0; i < 2; i++) {

    /* get motion code */
    diff = get_vlc2(bitbuf, svq1_motion_component.table, 7, 2);
    if(diff<0)
        return -1;
    else if(diff){
        if(get_bits1(bitbuf)) diff= -diff;
    }

    /* add median of motion vector predictors and clip result */
    if (i == 1)
      mv->y = sign_extend(diff + mid_pred(pmv[0]->y, pmv[1]->y, pmv[2]->y), 6);
    else
      mv->x = sign_extend(diff + mid_pred(pmv[0]->x, pmv[1]->x, pmv[2]->x), 6);
  }

  return 0;
}

static void svq1_skip_block (uint8_t *current, uint8_t *previous, int pitch, int x, int y) {
  uint8_t *src;
  uint8_t *dst;
  int      i;

  src = &previous[x + y*pitch];
  dst = current;

  for (i=0; i < 16; i++) {
    memcpy (dst, src, 16);
    src += pitch;
    dst += pitch;
  }
}

static int svq1_motion_inter_block (MpegEncContext *s, GetBitContext *bitbuf,
                               uint8_t *current, uint8_t *previous, int pitch,
                               svq1_pmv *motion, int x, int y) {
  uint8_t    *src;
  uint8_t    *dst;
  svq1_pmv    mv;
  svq1_pmv   *pmv[3];
  int         result;

  /* predict and decode motion vector */
  pmv[0] = &motion[0];
  if (y == 0) {
    pmv[1] =
    pmv[2] = pmv[0];
  }
  else {
    pmv[1] = &motion[(x / 8) + 2];
    pmv[2] = &motion[(x / 8) + 4];
  }

  result = svq1_decode_motion_vector (bitbuf, &mv, pmv);

  if (result != 0)
    return result;

  motion[0].x                =
  motion[(x / 8) + 2].x      =
  motion[(x / 8) + 3].x      = mv.x;
  motion[0].y                =
  motion[(x / 8) + 2].y      =
  motion[(x / 8) + 3].y      = mv.y;

  if(y + (mv.y >> 1)<0)
     mv.y= 0;
  if(x + (mv.x >> 1)<0)
     mv.x= 0;

  src = &previous[(x + (mv.x >> 1)) + (y + (mv.y >> 1))*pitch];
  dst = current;

  s->dsp.put_pixels_tab[0][((mv.y & 1) << 1) | (mv.x & 1)](dst,src,pitch,16);

  return 0;
}

static int svq1_motion_inter_4v_block (MpegEncContext *s, GetBitContext *bitbuf,
                                  uint8_t *current, uint8_t *previous, int pitch,
                                  svq1_pmv *motion,int x, int y) {
  uint8_t    *src;
  uint8_t    *dst;
  svq1_pmv    mv;
  svq1_pmv   *pmv[4];
  int         i, result;

  /* predict and decode motion vector (0) */
  pmv[0] = &motion[0];
  if (y == 0) {
    pmv[1] =
    pmv[2] = pmv[0];
  }
  else {
    pmv[1] = &motion[(x / 8) + 2];
    pmv[2] = &motion[(x / 8) + 4];
  }

  result = svq1_decode_motion_vector (bitbuf, &mv, pmv);

  if (result != 0)
    return result;

  /* predict and decode motion vector (1) */
  pmv[0] = &mv;
  if (y == 0) {
    pmv[1] =
    pmv[2] = pmv[0];
  }
  else {
    pmv[1] = &motion[(x / 8) + 3];
  }
  result = svq1_decode_motion_vector (bitbuf, &motion[0], pmv);

  if (result != 0)
    return result;

  /* predict and decode motion vector (2) */
  pmv[1] = &motion[0];
  pmv[2] = &motion[(x / 8) + 1];

  result = svq1_decode_motion_vector (bitbuf, &motion[(x / 8) + 2], pmv);

  if (result != 0)
    return result;

  /* predict and decode motion vector (3) */
  pmv[2] = &motion[(x / 8) + 2];
  pmv[3] = &motion[(x / 8) + 3];

  result = svq1_decode_motion_vector (bitbuf, pmv[3], pmv);

  if (result != 0)
    return result;

  /* form predictions */
  for (i=0; i < 4; i++) {
    int mvx= pmv[i]->x + (i&1)*16;
    int mvy= pmv[i]->y + (i>>1)*16;

    ///XXX /FIXME clipping or padding?
    if(y + (mvy >> 1)<0)
       mvy= 0;
    if(x + (mvx >> 1)<0)
       mvx= 0;

    src = &previous[(x + (mvx >> 1)) + (y + (mvy >> 1))*pitch];
    dst = current;

    s->dsp.put_pixels_tab[1][((mvy & 1) << 1) | (mvx & 1)](dst,src,pitch,8);

    /* select next block */
    if (i & 1) {
      current  += 8*(pitch - 1);
    } else {
      current  += 8;
    }
  }

  return 0;
}

static int svq1_decode_delta_block (MpegEncContext *s, GetBitContext *bitbuf,
                        uint8_t *current, uint8_t *previous, int pitch,
                        svq1_pmv *motion, int x, int y) {
  uint32_t block_type;
  int      result = 0;

  /* get block type */
  block_type = get_vlc2(bitbuf, svq1_block_type.table, 2, 2);

  /* reset motion vectors */
  if (block_type == SVQ1_BLOCK_SKIP || block_type == SVQ1_BLOCK_INTRA) {
    motion[0].x                 =
    motion[0].y                 =
    motion[(x / 8) + 2].x =
    motion[(x / 8) + 2].y =
    motion[(x / 8) + 3].x =
    motion[(x / 8) + 3].y = 0;
  }

  switch (block_type) {
  case SVQ1_BLOCK_SKIP:
    svq1_skip_block (current, previous, pitch, x, y);
    break;

  case SVQ1_BLOCK_INTER:
    result = svq1_motion_inter_block (s, bitbuf, current, previous, pitch, motion, x, y);

    if (result != 0)
    {
      av_dlog(s->avctx, "Error in svq1_motion_inter_block %i\n", result);
      break;
    }
    result = svq1_decode_block_non_intra (bitbuf, current, pitch);
    break;

  case SVQ1_BLOCK_INTER_4V:
    result = svq1_motion_inter_4v_block (s, bitbuf, current, previous, pitch, motion, x, y);

    if (result != 0)
    {
      av_dlog(s->avctx, "Error in svq1_motion_inter_4v_block %i\n", result);
      break;
    }
    result = svq1_decode_block_non_intra (bitbuf, current, pitch);
    break;

  case SVQ1_BLOCK_INTRA:
    result = svq1_decode_block_intra (bitbuf, current, pitch);
    break;
  }

  return result;
}

uint16_t ff_svq1_packet_checksum (const uint8_t *data, const int length, int value) {
  int i;

  for (i=0; i < length; i++) {
    value = checksum_table[data[i] ^ (value >> 8)] ^ ((value & 0xFF) << 8);
  }

  return value;
}

static void svq1_parse_string (GetBitContext *bitbuf, uint8_t *out) {
  uint8_t seed;
  int     i;

  out[0] = get_bits (bitbuf, 8);

  seed = string_table[out[0]];

  for (i=1; i <= out[0]; i++) {
    out[i] = get_bits (bitbuf, 8) ^ seed;
    seed   = string_table[out[i] ^ seed];
  }
}

static int svq1_decode_frame_header (GetBitContext *bitbuf,MpegEncContext *s) {
  int frame_size_code;

  skip_bits(bitbuf, 8); /* temporal_reference */

  /* frame type */
  s->pict_type= get_bits (bitbuf, 2)+1;
  if(s->pict_type==4)
      return -1;

  if (s->pict_type == AV_PICTURE_TYPE_I) {

    /* unknown fields */
    if (s->f_code == 0x50 || s->f_code == 0x60) {
      int csum = get_bits (bitbuf, 16);

      csum = ff_svq1_packet_checksum (bitbuf->buffer, bitbuf->size_in_bits>>3, csum);

//      av_log(s->avctx, AV_LOG_INFO, "%s checksum (%02x) for packet data\n",
//              (csum == 0) ? "correct" : "incorrect", csum);
    }

    if ((s->f_code ^ 0x10) >= 0x50) {
      uint8_t msg[256];

      svq1_parse_string (bitbuf, msg);

      av_log(s->avctx, AV_LOG_INFO, "embedded message: \"%s\"\n", (char *) msg);
    }

    skip_bits (bitbuf, 2);
    skip_bits (bitbuf, 2);
    skip_bits1 (bitbuf);

    /* load frame size */
    frame_size_code = get_bits (bitbuf, 3);

    if (frame_size_code == 7) {
      /* load width, height (12 bits each) */
      s->width = get_bits (bitbuf, 12);
      s->height = get_bits (bitbuf, 12);

      if (!s->width || !s->height)
        return -1;
    } else {
      /* get width, height from table */
      s->width = ff_svq1_frame_size_table[frame_size_code].width;
      s->height = ff_svq1_frame_size_table[frame_size_code].height;
    }
  }

  /* unknown fields */
  if (get_bits1 (bitbuf) == 1) {
    skip_bits1 (bitbuf);       /* use packet checksum if (1) */
    skip_bits1 (bitbuf);       /* component checksums after image data if (1) */

    if (get_bits (bitbuf, 2) != 0)
      return -1;
  }

  if (get_bits1 (bitbuf) == 1) {
    skip_bits1 (bitbuf);
    skip_bits (bitbuf, 4);
    skip_bits1 (bitbuf);
    skip_bits (bitbuf, 2);

    while (get_bits1 (bitbuf) == 1) {
      skip_bits (bitbuf, 8);
    }
  }

  return 0;
}

static int svq1_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,
                             AVPacket *avpkt)
{
  const uint8_t *buf = avpkt->data;
  int buf_size = avpkt->size;
  MpegEncContext *s=avctx->priv_data;
  uint8_t        *current, *previous;
  int             result, i, x, y, width, height;
  AVFrame *pict = data;
  svq1_pmv *pmv;

  /* initialize bit buffer */
  init_get_bits(&s->gb,buf,buf_size*8);

  /* decode frame header */
  s->f_code = get_bits (&s->gb, 22);

  if ((s->f_code & ~0x70) || !(s->f_code & 0x60))
    return -1;

  /* swap some header bytes (why?) */
  if (s->f_code != 0x20) {
    uint32_t *src = (uint32_t *) (buf + 4);

    for (i=0; i < 4; i++) {
      src[i] = ((src[i] << 16) | (src[i] >> 16)) ^ src[7 - i];
    }
  }

  result = svq1_decode_frame_header (&s->gb, s);

  if (result != 0)
  {
    av_dlog(s->avctx, "Error in svq1_decode_frame_header %i\n",result);
    return result;
  }
  avcodec_set_dimensions(avctx, s->width, s->height);

  //FIXME this avoids some confusion for "B frames" without 2 references
  //this should be removed after libavcodec can handle more flexible picture types & ordering
  if(s->pict_type==AV_PICTURE_TYPE_B && s->last_picture_ptr==NULL) return buf_size;

  if(  (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
     ||(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
     || avctx->skip_frame >= AVDISCARD_ALL)
      return buf_size;

  if(ff_MPV_frame_start(s, avctx) < 0)
      return -1;

  pmv = av_malloc((FFALIGN(s->width, 16)/8 + 3) * sizeof(*pmv));
  if (!pmv)
      return -1;

  /* decode y, u and v components */
  for (i=0; i < 3; i++) {
    int linesize;
    if (i == 0) {
      width  = FFALIGN(s->width, 16);
      height = FFALIGN(s->height, 16);
      linesize= s->linesize;
    } else {
      if(s->flags&CODEC_FLAG_GRAY) break;
      width  = FFALIGN(s->width/4, 16);
      height = FFALIGN(s->height/4, 16);
      linesize= s->uvlinesize;
    }

    current = s->current_picture.f.data[i];

    if(s->pict_type==AV_PICTURE_TYPE_B){
        previous = s->next_picture.f.data[i];
    }else{
        previous = s->last_picture.f.data[i];
    }

    if (s->pict_type == AV_PICTURE_TYPE_I) {
      /* keyframe */
      for (y=0; y < height; y+=16) {
        for (x=0; x < width; x+=16) {
          result = svq1_decode_block_intra (&s->gb, &current[x], linesize);
          if (result != 0)
          {
            av_log(s->avctx, AV_LOG_INFO, "Error in svq1_decode_block %i (keyframe)\n",result);
            goto err;
          }
        }
        current += 16*linesize;
      }
    } else {
      /* delta frame */
      memset (pmv, 0, ((width / 8) + 3) * sizeof(svq1_pmv));

      for (y=0; y < height; y+=16) {
        for (x=0; x < width; x+=16) {
          result = svq1_decode_delta_block (s, &s->gb, &current[x], previous,
                                            linesize, pmv, x, y);
          if (result != 0)
          {
            av_dlog(s->avctx, "Error in svq1_decode_delta_block %i\n",result);
            goto err;
          }
        }

        pmv[0].x =
        pmv[0].y = 0;

        current += 16*linesize;
      }
    }
  }

  *pict = s->current_picture.f;


  ff_MPV_frame_end(s);

  *data_size=sizeof(AVFrame);
  result = buf_size;
err:
  av_free(pmv);
  return result;
}

static av_cold int svq1_decode_init(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;
    int i;
    int offset = 0;

    ff_MPV_decode_defaults(s);

    s->avctx = avctx;
    s->width = (avctx->width+3)&~3;
    s->height = (avctx->height+3)&~3;
    s->codec_id= avctx->codec->id;
    avctx->pix_fmt = PIX_FMT_YUV410P;
    avctx->has_b_frames= 1; // not true, but DP frames and these behave like unidirectional b frames
    s->flags= avctx->flags;
    if (ff_MPV_common_init(s) < 0) return -1;

    INIT_VLC_STATIC(&svq1_block_type, 2, 4,
        &ff_svq1_block_type_vlc[0][1], 2, 1,
        &ff_svq1_block_type_vlc[0][0], 2, 1, 6);

    INIT_VLC_STATIC(&svq1_motion_component, 7, 33,
        &ff_mvtab[0][1], 2, 1,
        &ff_mvtab[0][0], 2, 1, 176);

    for (i = 0; i < 6; i++) {
        static const uint8_t sizes[2][6] = {{14, 10, 14, 18, 16, 18}, {10, 10, 14, 14, 14, 16}};
        static VLC_TYPE table[168][2];
        svq1_intra_multistage[i].table = &table[offset];
        svq1_intra_multistage[i].table_allocated = sizes[0][i];
        offset += sizes[0][i];
        init_vlc(&svq1_intra_multistage[i], 3, 8,
            &ff_svq1_intra_multistage_vlc[i][0][1], 2, 1,
            &ff_svq1_intra_multistage_vlc[i][0][0], 2, 1, INIT_VLC_USE_NEW_STATIC);
        svq1_inter_multistage[i].table = &table[offset];
        svq1_inter_multistage[i].table_allocated = sizes[1][i];
        offset += sizes[1][i];
        init_vlc(&svq1_inter_multistage[i], 3, 8,
            &ff_svq1_inter_multistage_vlc[i][0][1], 2, 1,
            &ff_svq1_inter_multistage_vlc[i][0][0], 2, 1, INIT_VLC_USE_NEW_STATIC);
    }

    INIT_VLC_STATIC(&svq1_intra_mean, 8, 256,
        &ff_svq1_intra_mean_vlc[0][1], 4, 2,
        &ff_svq1_intra_mean_vlc[0][0], 4, 2, 632);

    INIT_VLC_STATIC(&svq1_inter_mean, 9, 512,
        &ff_svq1_inter_mean_vlc[0][1], 4, 2,
        &ff_svq1_inter_mean_vlc[0][0], 4, 2, 1434);

    return 0;
}

static av_cold int svq1_decode_end(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;

    ff_MPV_common_end(s);
    return 0;
}


AVCodec ff_svq1_decoder = {
    .name           = "svq1",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_SVQ1,
    .priv_data_size = sizeof(MpegEncContext),
    .init           = svq1_decode_init,
    .close          = svq1_decode_end,
    .decode         = svq1_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .flush          = ff_mpeg_flush,
    .pix_fmts       = (const enum PixelFormat[]){ PIX_FMT_YUV410P, PIX_FMT_NONE },
    .long_name      = NULL_IF_CONFIG_SMALL("Sorenson Vector Quantizer 1 / Sorenson Video 1 / SVQ1"),
};