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ituh263dec.c
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1 /*
2  * ITU H263 bitstream decoder
3  * Copyright (c) 2000,2001 Fabrice Bellard
4  * H263+ support.
5  * Copyright (c) 2001 Juan J. Sierralta P
6  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 /**
26  * @file
27  * h263 decoder.
28  */
29 
30 #define UNCHECKED_BITSTREAM_READER 1
31 
32 //#define DEBUG
33 #include <limits.h>
34 
35 #include "libavutil/internal.h"
36 #include "libavutil/mathematics.h"
37 #include "avcodec.h"
38 #include "mpegvideo.h"
39 #include "h263.h"
40 #include "mathops.h"
41 #include "unary.h"
42 #include "flv.h"
43 #include "mpeg4video.h"
44 
45 // The defines below define the number of bits that are read at once for
46 // reading vlc values. Changing these may improve speed and data cache needs
47 // be aware though that decreasing them may need the number of stages that is
48 // passed to get_vlc* to be increased.
49 #define MV_VLC_BITS 9
50 #define H263_MBTYPE_B_VLC_BITS 6
51 #define CBPC_B_VLC_BITS 3
52 
53 static const int h263_mb_type_b_map[15]= {
66  0, //stuffing
69 };
70 
73  av_log(s->avctx, AV_LOG_DEBUG, "qp:%d %c size:%d rnd:%d%s%s%s%s%s%s%s%s%s %d/%d\n",
75  s->gb.size_in_bits, 1-s->no_rounding,
76  s->obmc ? " AP" : "",
77  s->umvplus ? " UMV" : "",
78  s->h263_long_vectors ? " LONG" : "",
79  s->h263_plus ? " +" : "",
80  s->h263_aic ? " AIC" : "",
81  s->alt_inter_vlc ? " AIV" : "",
82  s->modified_quant ? " MQ" : "",
83  s->loop_filter ? " LOOP" : "",
84  s->h263_slice_structured ? " SS" : "",
86  );
87  }
88 }
89 
90 /***********************************************/
91 /* decoding */
92 
96 static VLC mv_vlc;
98 static VLC cbpc_b_vlc;
99 
100 /* init vlcs */
101 
102 /* XXX: find a better solution to handle static init */
104 {
105  static volatile int done = 0;
106 
107  if (!done) {
108  INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
110  ff_h263_intra_MCBPC_code, 1, 1, 72);
111  INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
113  ff_h263_inter_MCBPC_code, 1, 1, 198);
114  INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
115  &ff_h263_cbpy_tab[0][1], 2, 1,
116  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
117  INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
118  &ff_mvtab[0][1], 2, 1,
119  &ff_mvtab[0][0], 2, 1, 538);
124  INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
125  &ff_h263_mbtype_b_tab[0][1], 2, 1,
126  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
127  INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
128  &ff_cbpc_b_tab[0][1], 2, 1,
129  &ff_cbpc_b_tab[0][0], 2, 1, 8);
130  done = 1;
131  }
132 }
133 
135 {
136  int i, mb_pos;
137 
138  for(i=0; i<6; i++){
139  if(s->mb_num-1 <= ff_mba_max[i]) break;
140  }
141  mb_pos= get_bits(&s->gb, ff_mba_length[i]);
142  s->mb_x= mb_pos % s->mb_width;
143  s->mb_y= mb_pos / s->mb_width;
144 
145  return mb_pos;
146 }
147 
148 /**
149  * Decode the group of blocks header or slice header.
150  * @return <0 if an error occurred
151  */
153 {
154  unsigned int val, gob_number;
155  int left;
156 
157  /* Check for GOB Start Code */
158  val = show_bits(&s->gb, 16);
159  if(val)
160  return -1;
161 
162  /* We have a GBSC probably with GSTUFF */
163  skip_bits(&s->gb, 16); /* Drop the zeros */
164  left= get_bits_left(&s->gb);
165  //MN: we must check the bits left or we might end in a infinite loop (or segfault)
166  for(;left>13; left--){
167  if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
168  }
169  if(left<=13)
170  return -1;
171 
172  if(s->h263_slice_structured){
173  if(get_bits1(&s->gb)==0)
174  return -1;
175 
177 
178  if(s->mb_num > 1583)
179  if(get_bits1(&s->gb)==0)
180  return -1;
181 
182  s->qscale = get_bits(&s->gb, 5); /* SQUANT */
183  if(get_bits1(&s->gb)==0)
184  return -1;
185  skip_bits(&s->gb, 2); /* GFID */
186  }else{
187  gob_number = get_bits(&s->gb, 5); /* GN */
188  s->mb_x= 0;
189  s->mb_y= s->gob_index* gob_number;
190  skip_bits(&s->gb, 2); /* GFID */
191  s->qscale = get_bits(&s->gb, 5); /* GQUANT */
192  }
193 
194  if(s->mb_y >= s->mb_height)
195  return -1;
196 
197  if(s->qscale==0)
198  return -1;
199 
200  return 0;
201 }
202 
203 /**
204  * Find the next resync_marker.
205  * @param p pointer to buffer to scan
206  * @param end pointer to the end of the buffer
207  * @return pointer to the next resync_marker, or end if none was found
208  */
210 {
211  av_assert2(p < end);
212 
213  end-=2;
214  p++;
215  if(s->resync_marker){
216  int prefix_len = ff_mpeg4_get_video_packet_prefix_length(s);
217  for(;p<end; p+=2){
218  if(!*p){
219  if (!p[-1] && ((p[1] >> (23-prefix_len)) == 1)) return p - 1;
220  else if (!p[ 1] && ((p[2] >> (23-prefix_len)) == 1)) return p;
221  }
222  }
223  }
224  return end+2;
225 }
226 
227 /**
228  * Decode the group of blocks / video packet header.
229  * @return bit position of the resync_marker, or <0 if none was found
230  */
232  int left, pos, ret;
233 
234  if(s->codec_id==AV_CODEC_ID_MPEG4){
235  skip_bits1(&s->gb);
236  align_get_bits(&s->gb);
237  }
238 
239  if(show_bits(&s->gb, 16)==0){
240  pos= get_bits_count(&s->gb);
241  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
243  else
244  ret= h263_decode_gob_header(s);
245  if(ret>=0)
246  return pos;
247  }
248  //OK, it's not where it is supposed to be ...
249  s->gb= s->last_resync_gb;
250  align_get_bits(&s->gb);
251  left= get_bits_left(&s->gb);
252 
253  for(;left>16+1+5+5; left-=8){
254  if(show_bits(&s->gb, 16)==0){
255  GetBitContext bak= s->gb;
256 
257  pos= get_bits_count(&s->gb);
258  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
260  else
261  ret= h263_decode_gob_header(s);
262  if(ret>=0)
263  return pos;
264 
265  s->gb= bak;
266  }
267  skip_bits(&s->gb, 8);
268  }
269 
270  return -1;
271 }
272 
273 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
274 {
275  int code, val, sign, shift;
276  code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
277 
278  if (code == 0)
279  return pred;
280  if (code < 0)
281  return 0xffff;
282 
283  sign = get_bits1(&s->gb);
284  shift = f_code - 1;
285  val = code;
286  if (shift) {
287  val = (val - 1) << shift;
288  val |= get_bits(&s->gb, shift);
289  val++;
290  }
291  if (sign)
292  val = -val;
293  val += pred;
294 
295  /* modulo decoding */
296  if (!s->h263_long_vectors) {
297  val = sign_extend(val, 5 + f_code);
298  } else {
299  /* horrible h263 long vector mode */
300  if (pred < -31 && val < -63)
301  val += 64;
302  if (pred > 32 && val > 63)
303  val -= 64;
304 
305  }
306  return val;
307 }
308 
309 
310 /* Decode RVLC of H.263+ UMV */
312 {
313  int code = 0, sign;
314 
315  if (get_bits1(&s->gb)) /* Motion difference = 0 */
316  return pred;
317 
318  code = 2 + get_bits1(&s->gb);
319 
320  while (get_bits1(&s->gb))
321  {
322  code <<= 1;
323  code += get_bits1(&s->gb);
324  }
325  sign = code & 1;
326  code >>= 1;
327 
328  code = (sign) ? (pred - code) : (pred + code);
329  av_dlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
330  return code;
331 
332 }
333 
334 /**
335  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
336  */
337 static void preview_obmc(MpegEncContext *s){
338  GetBitContext gb= s->gb;
339 
340  int cbpc, i, pred_x, pred_y, mx, my;
341  int16_t *mot_val;
342  const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
343  const int stride= s->b8_stride*2;
344 
345  for(i=0; i<4; i++)
346  s->block_index[i]+= 2;
347  for(i=4; i<6; i++)
348  s->block_index[i]+= 1;
349  s->mb_x++;
350 
352 
353  do{
354  if (get_bits1(&s->gb)) {
355  /* skip mb */
356  mot_val = s->current_picture.f.motion_val[0][s->block_index[0]];
357  mot_val[0 ]= mot_val[2 ]=
358  mot_val[0+stride]= mot_val[2+stride]= 0;
359  mot_val[1 ]= mot_val[3 ]=
360  mot_val[1+stride]= mot_val[3+stride]= 0;
361 
363  goto end;
364  }
365  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
366  }while(cbpc == 20);
367 
368  if(cbpc & 4){
370  }else{
371  get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
372  if (cbpc & 8) {
373  if(s->modified_quant){
374  if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
375  else skip_bits(&s->gb, 5);
376  }else
377  skip_bits(&s->gb, 2);
378  }
379 
380  if ((cbpc & 16) == 0) {
382  /* 16x16 motion prediction */
383  mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
384  if (s->umvplus)
385  mx = h263p_decode_umotion(s, pred_x);
386  else
387  mx = ff_h263_decode_motion(s, pred_x, 1);
388 
389  if (s->umvplus)
390  my = h263p_decode_umotion(s, pred_y);
391  else
392  my = ff_h263_decode_motion(s, pred_y, 1);
393 
394  mot_val[0 ]= mot_val[2 ]=
395  mot_val[0+stride]= mot_val[2+stride]= mx;
396  mot_val[1 ]= mot_val[3 ]=
397  mot_val[1+stride]= mot_val[3+stride]= my;
398  } else {
400  for(i=0;i<4;i++) {
401  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
402  if (s->umvplus)
403  mx = h263p_decode_umotion(s, pred_x);
404  else
405  mx = ff_h263_decode_motion(s, pred_x, 1);
406 
407  if (s->umvplus)
408  my = h263p_decode_umotion(s, pred_y);
409  else
410  my = ff_h263_decode_motion(s, pred_y, 1);
411  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
412  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
413  mot_val[0] = mx;
414  mot_val[1] = my;
415  }
416  }
417  }
418 end:
419 
420  for(i=0; i<4; i++)
421  s->block_index[i]-= 2;
422  for(i=4; i<6; i++)
423  s->block_index[i]-= 1;
424  s->mb_x--;
425 
426  s->gb= gb;
427 }
428 
430  static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
431 
432  if(s->modified_quant){
433  if(get_bits1(&s->gb))
435  else
436  s->qscale= get_bits(&s->gb, 5);
437  }else
438  s->qscale += quant_tab[get_bits(&s->gb, 2)];
439  ff_set_qscale(s, s->qscale);
440 }
441 
442 static int h263_decode_block(MpegEncContext * s, int16_t * block,
443  int n, int coded)
444 {
445  int code, level, i, j, last, run;
446  RLTable *rl = &ff_h263_rl_inter;
447  const uint8_t *scan_table;
448  GetBitContext gb= s->gb;
449 
450  scan_table = s->intra_scantable.permutated;
451  if (s->h263_aic && s->mb_intra) {
452  rl = &ff_rl_intra_aic;
453  i = 0;
454  if (s->ac_pred) {
455  if (s->h263_aic_dir)
456  scan_table = s->intra_v_scantable.permutated; /* left */
457  else
458  scan_table = s->intra_h_scantable.permutated; /* top */
459  }
460  } else if (s->mb_intra) {
461  /* DC coef */
462  if(s->codec_id == AV_CODEC_ID_RV10){
463 #if CONFIG_RV10_DECODER
464  if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
465  int component, diff;
466  component = (n <= 3 ? 0 : n - 4 + 1);
467  level = s->last_dc[component];
468  if (s->rv10_first_dc_coded[component]) {
469  diff = ff_rv_decode_dc(s, n);
470  if (diff == 0xffff)
471  return -1;
472  level += diff;
473  level = level & 0xff; /* handle wrap round */
474  s->last_dc[component] = level;
475  } else {
476  s->rv10_first_dc_coded[component] = 1;
477  }
478  } else {
479  level = get_bits(&s->gb, 8);
480  if (level == 255)
481  level = 128;
482  }
483 #endif
484  }else{
485  level = get_bits(&s->gb, 8);
486  if((level&0x7F) == 0){
487  av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
489  return -1;
490  }
491  if (level == 255)
492  level = 128;
493  }
494  block[0] = level;
495  i = 1;
496  } else {
497  i = 0;
498  }
499  if (!coded) {
500  if (s->mb_intra && s->h263_aic)
501  goto not_coded;
502  s->block_last_index[n] = i - 1;
503  return 0;
504  }
505 retry:
506  for(;;) {
507  code = get_vlc2(&s->gb, rl->vlc.table, TEX_VLC_BITS, 2);
508  if (code < 0){
509  av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
510  return -1;
511  }
512  if (code == rl->n) {
513  /* escape */
514  if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
515  ff_flv2_decode_ac_esc(&s->gb, &level, &run, &last);
516  } else {
517  last = get_bits1(&s->gb);
518  run = get_bits(&s->gb, 6);
519  level = (int8_t)get_bits(&s->gb, 8);
520  if(level == -128){
521  if (s->codec_id == AV_CODEC_ID_RV10) {
522  /* XXX: should patch encoder too */
523  level = get_sbits(&s->gb, 12);
524  }else{
525  level = get_bits(&s->gb, 5);
526  level |= get_sbits(&s->gb, 6)<<5;
527  }
528  }
529  }
530  } else {
531  run = rl->table_run[code];
532  level = rl->table_level[code];
533  last = code >= rl->last;
534  if (get_bits1(&s->gb))
535  level = -level;
536  }
537  i += run;
538  if (i >= 64){
539  if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
540  //Looks like a hack but no, it's the way it is supposed to work ...
541  rl = &ff_rl_intra_aic;
542  i = 0;
543  s->gb= gb;
544  s->dsp.clear_block(block);
545  goto retry;
546  }
547  av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
548  return -1;
549  }
550  j = scan_table[i];
551  block[j] = level;
552  if (last)
553  break;
554  i++;
555  }
556 not_coded:
557  if (s->mb_intra && s->h263_aic) {
558  ff_h263_pred_acdc(s, block, n);
559  i = 63;
560  }
561  s->block_last_index[n] = i;
562  return 0;
563 }
564 
565 static int h263_skip_b_part(MpegEncContext *s, int cbp)
566 {
567  LOCAL_ALIGNED_16(int16_t, dblock, [64]);
568  int i, mbi;
569  int bli[6];
570 
571  /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
572  * but real value should be restored in order to be used later (in OBMC condition)
573  */
574  mbi = s->mb_intra;
575  memcpy(bli, s->block_last_index, sizeof(bli));
576  s->mb_intra = 0;
577  for (i = 0; i < 6; i++) {
578  if (h263_decode_block(s, dblock, i, cbp&32) < 0)
579  return -1;
580  cbp+=cbp;
581  }
582  s->mb_intra = mbi;
583  memcpy(s->block_last_index, bli, sizeof(bli));
584  return 0;
585 }
586 
587 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
588 {
589  int c, mv = 1;
590 
591  if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
592  c = get_bits1(gb);
593  if (pb_frame == 2 && c)
594  mv = !get_bits1(gb);
595  } else { // h.263 Annex M improved PB-frame
596  mv = get_unary(gb, 0, 4) + 1;
597  c = mv & 1;
598  mv = !!(mv & 2);
599  }
600  if(c)
601  *cbpb = get_bits(gb, 6);
602  return mv;
603 }
604 
606  int16_t block[6][64])
607 {
608  int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
609  int16_t *mot_val;
610  const int xy= s->mb_x + s->mb_y * s->mb_stride;
611  int cbpb = 0, pb_mv_count = 0;
612 
613  av_assert2(!s->h263_pred);
614 
615  if (s->pict_type == AV_PICTURE_TYPE_P) {
616  do{
617  if (get_bits1(&s->gb)) {
618  /* skip mb */
619  s->mb_intra = 0;
620  for(i=0;i<6;i++)
621  s->block_last_index[i] = -1;
622  s->mv_dir = MV_DIR_FORWARD;
623  s->mv_type = MV_TYPE_16X16;
625  s->mv[0][0][0] = 0;
626  s->mv[0][0][1] = 0;
627  s->mb_skipped = !(s->obmc | s->loop_filter);
628  goto end;
629  }
630  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
631  if (cbpc < 0){
632  av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
633  return -1;
634  }
635  }while(cbpc == 20);
636 
637  s->dsp.clear_blocks(s->block[0]);
638 
639  dquant = cbpc & 8;
640  s->mb_intra = ((cbpc & 4) != 0);
641  if (s->mb_intra) goto intra;
642 
643  if(s->pb_frame && get_bits1(&s->gb))
644  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
645  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
646 
647  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
648  cbpy ^= 0xF;
649 
650  cbp = (cbpc & 3) | (cbpy << 2);
651  if (dquant) {
653  }
654 
655  s->mv_dir = MV_DIR_FORWARD;
656  if ((cbpc & 16) == 0) {
658  /* 16x16 motion prediction */
659  s->mv_type = MV_TYPE_16X16;
660  ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
661  if (s->umvplus)
662  mx = h263p_decode_umotion(s, pred_x);
663  else
664  mx = ff_h263_decode_motion(s, pred_x, 1);
665 
666  if (mx >= 0xffff)
667  return -1;
668 
669  if (s->umvplus)
670  my = h263p_decode_umotion(s, pred_y);
671  else
672  my = ff_h263_decode_motion(s, pred_y, 1);
673 
674  if (my >= 0xffff)
675  return -1;
676  s->mv[0][0][0] = mx;
677  s->mv[0][0][1] = my;
678 
679  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
680  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
681  } else {
683  s->mv_type = MV_TYPE_8X8;
684  for(i=0;i<4;i++) {
685  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
686  if (s->umvplus)
687  mx = h263p_decode_umotion(s, pred_x);
688  else
689  mx = ff_h263_decode_motion(s, pred_x, 1);
690  if (mx >= 0xffff)
691  return -1;
692 
693  if (s->umvplus)
694  my = h263p_decode_umotion(s, pred_y);
695  else
696  my = ff_h263_decode_motion(s, pred_y, 1);
697  if (my >= 0xffff)
698  return -1;
699  s->mv[0][i][0] = mx;
700  s->mv[0][i][1] = my;
701  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
702  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
703  mot_val[0] = mx;
704  mot_val[1] = my;
705  }
706  }
707  } else if(s->pict_type==AV_PICTURE_TYPE_B) {
708  int mb_type;
709  const int stride= s->b8_stride;
710  int16_t *mot_val0 = s->current_picture.f.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
711  int16_t *mot_val1 = s->current_picture.f.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
712 // const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
713 
714  //FIXME ugly
715  mot_val0[0 ]= mot_val0[2 ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
716  mot_val0[1 ]= mot_val0[3 ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
717  mot_val1[0 ]= mot_val1[2 ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
718  mot_val1[1 ]= mot_val1[3 ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
719 
720  do{
721  mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
722  if (mb_type < 0){
723  av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
724  return -1;
725  }
726 
727  mb_type= h263_mb_type_b_map[ mb_type ];
728  }while(!mb_type);
729 
730  s->mb_intra = IS_INTRA(mb_type);
731  if(HAS_CBP(mb_type)){
732  s->dsp.clear_blocks(s->block[0]);
733  cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
734  if(s->mb_intra){
735  dquant = IS_QUANT(mb_type);
736  goto intra;
737  }
738 
739  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
740 
741  if (cbpy < 0){
742  av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
743  return -1;
744  }
745 
746  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
747  cbpy ^= 0xF;
748 
749  cbp = (cbpc & 3) | (cbpy << 2);
750  }else
751  cbp=0;
752 
753  av_assert2(!s->mb_intra);
754 
755  if(IS_QUANT(mb_type)){
757  }
758 
759  if(IS_DIRECT(mb_type)){
761  mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
762  }else{
763  s->mv_dir = 0;
765 //FIXME UMV
766 
767  if(USES_LIST(mb_type, 0)){
768  int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
769  s->mv_dir = MV_DIR_FORWARD;
770 
771  mx = ff_h263_decode_motion(s, mx, 1);
772  my = ff_h263_decode_motion(s, my, 1);
773 
774  s->mv[0][0][0] = mx;
775  s->mv[0][0][1] = my;
776  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
777  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
778  }
779 
780  if(USES_LIST(mb_type, 1)){
781  int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
782  s->mv_dir |= MV_DIR_BACKWARD;
783 
784  mx = ff_h263_decode_motion(s, mx, 1);
785  my = ff_h263_decode_motion(s, my, 1);
786 
787  s->mv[1][0][0] = mx;
788  s->mv[1][0][1] = my;
789  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
790  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
791  }
792  }
793 
794  s->current_picture.f.mb_type[xy] = mb_type;
795  } else { /* I-Frame */
796  do{
797  cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
798  if (cbpc < 0){
799  av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
800  return -1;
801  }
802  }while(cbpc == 8);
803 
804  s->dsp.clear_blocks(s->block[0]);
805 
806  dquant = cbpc & 4;
807  s->mb_intra = 1;
808 intra:
810  if (s->h263_aic) {
811  s->ac_pred = get_bits1(&s->gb);
812  if(s->ac_pred){
814 
815  s->h263_aic_dir = get_bits1(&s->gb);
816  }
817  }else
818  s->ac_pred = 0;
819 
820  if(s->pb_frame && get_bits1(&s->gb))
821  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
822  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
823  if(cbpy<0){
824  av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
825  return -1;
826  }
827  cbp = (cbpc & 3) | (cbpy << 2);
828  if (dquant) {
830  }
831 
832  pb_mv_count += !!s->pb_frame;
833  }
834 
835  while(pb_mv_count--){
836  ff_h263_decode_motion(s, 0, 1);
837  ff_h263_decode_motion(s, 0, 1);
838  }
839 
840  /* decode each block */
841  for (i = 0; i < 6; i++) {
842  if (h263_decode_block(s, block[i], i, cbp&32) < 0)
843  return -1;
844  cbp+=cbp;
845  }
846 
847  if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
848  return -1;
849  if(s->obmc && !s->mb_intra){
850  if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
851  preview_obmc(s);
852  }
853 end:
854 
855  /* per-MB end of slice check */
856  {
857  int v= show_bits(&s->gb, 16);
858 
859  if (get_bits_left(&s->gb) < 16) {
860  v >>= 16 - get_bits_left(&s->gb);
861  }
862 
863  if(v==0)
864  return SLICE_END;
865  }
866 
867  return SLICE_OK;
868 }
869 
870 /* most is hardcoded. should extend to handle all h263 streams */
872 {
873  int format, width, height, i;
874  uint32_t startcode;
875 
876  align_get_bits(&s->gb);
877 
878  startcode= get_bits(&s->gb, 22-8);
879 
880  for(i= get_bits_left(&s->gb); i>24; i-=8) {
881  startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
882 
883  if(startcode == 0x20)
884  break;
885  }
886 
887  if (startcode != 0x20) {
888  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
889  return -1;
890  }
891  /* temporal reference */
892  i = get_bits(&s->gb, 8); /* picture timestamp */
893  if( (s->picture_number&~0xFF)+i < s->picture_number)
894  i+= 256;
896  s->picture_number= (s->picture_number&~0xFF) + i;
897 
898  /* PTYPE starts here */
899  if (get_bits1(&s->gb) != 1) {
900  /* marker */
901  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
902  return -1;
903  }
904  if (get_bits1(&s->gb) != 0) {
905  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
906  return -1; /* h263 id */
907  }
908  skip_bits1(&s->gb); /* split screen off */
909  skip_bits1(&s->gb); /* camera off */
910  skip_bits1(&s->gb); /* freeze picture release off */
911 
912  format = get_bits(&s->gb, 3);
913  /*
914  0 forbidden
915  1 sub-QCIF
916  10 QCIF
917  7 extended PTYPE (PLUSPTYPE)
918  */
919 
920  if (format != 7 && format != 6) {
921  s->h263_plus = 0;
922  /* H.263v1 */
923  width = ff_h263_format[format][0];
924  height = ff_h263_format[format][1];
925  if (!width)
926  return -1;
927 
929 
930  s->h263_long_vectors = get_bits1(&s->gb);
931 
932  if (get_bits1(&s->gb) != 0) {
933  av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
934  return -1; /* SAC: off */
935  }
936  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
937  s->unrestricted_mv = s->h263_long_vectors || s->obmc;
938 
939  s->pb_frame = get_bits1(&s->gb);
940  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
941  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
942 
943  s->width = width;
944  s->height = height;
945  s->avctx->sample_aspect_ratio= (AVRational){12,11};
946  s->avctx->time_base= (AVRational){1001, 30000};
947  } else {
948  int ufep;
949 
950  /* H.263v2 */
951  s->h263_plus = 1;
952  ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
953 
954  /* ufep other than 0 and 1 are reserved */
955  if (ufep == 1) {
956  /* OPPTYPE */
957  format = get_bits(&s->gb, 3);
958  av_dlog(s->avctx, "ufep=1, format: %d\n", format);
959  s->custom_pcf= get_bits1(&s->gb);
960  s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
961  if (get_bits1(&s->gb) != 0) {
962  av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
963  }
964  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
965  s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
966  s->loop_filter= get_bits1(&s->gb);
967  s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
968  if(s->avctx->lowres)
969  s->loop_filter = 0;
970 
972  if (get_bits1(&s->gb) != 0) {
973  av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
974  }
975  if (get_bits1(&s->gb) != 0) {
976  av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
977  }
978  s->alt_inter_vlc= get_bits1(&s->gb);
979  s->modified_quant= get_bits1(&s->gb);
980  if(s->modified_quant)
982 
983  skip_bits(&s->gb, 1); /* Prevent start code emulation */
984 
985  skip_bits(&s->gb, 3); /* Reserved */
986  } else if (ufep != 0) {
987  av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
988  return -1;
989  }
990 
991  /* MPPTYPE */
992  s->pict_type = get_bits(&s->gb, 3);
993  switch(s->pict_type){
994  case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
995  case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
996  case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
997  case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
998  case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
999  default:
1000  return -1;
1001  }
1002  skip_bits(&s->gb, 2);
1003  s->no_rounding = get_bits1(&s->gb);
1004  skip_bits(&s->gb, 4);
1005 
1006  /* Get the picture dimensions */
1007  if (ufep) {
1008  if (format == 6) {
1009  /* Custom Picture Format (CPFMT) */
1010  s->aspect_ratio_info = get_bits(&s->gb, 4);
1011  av_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1012  /* aspect ratios:
1013  0 - forbidden
1014  1 - 1:1
1015  2 - 12:11 (CIF 4:3)
1016  3 - 10:11 (525-type 4:3)
1017  4 - 16:11 (CIF 16:9)
1018  5 - 40:33 (525-type 16:9)
1019  6-14 - reserved
1020  */
1021  width = (get_bits(&s->gb, 9) + 1) * 4;
1022  skip_bits1(&s->gb);
1023  height = get_bits(&s->gb, 9) * 4;
1024  av_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1026  /* aspected dimensions */
1027  s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1028  s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1029  }else{
1031  }
1032  } else {
1033  width = ff_h263_format[format][0];
1034  height = ff_h263_format[format][1];
1035  s->avctx->sample_aspect_ratio= (AVRational){12,11};
1036  }
1037  if ((width == 0) || (height == 0))
1038  return -1;
1039  s->width = width;
1040  s->height = height;
1041 
1042  if(s->custom_pcf){
1043  int gcd;
1044  s->avctx->time_base.den= 1800000;
1045  s->avctx->time_base.num= 1000 + get_bits1(&s->gb);
1046  s->avctx->time_base.num*= get_bits(&s->gb, 7);
1047  if(s->avctx->time_base.num == 0){
1048  av_log(s, AV_LOG_ERROR, "zero framerate\n");
1049  return -1;
1050  }
1051  gcd= av_gcd(s->avctx->time_base.den, s->avctx->time_base.num);
1052  s->avctx->time_base.den /= gcd;
1053  s->avctx->time_base.num /= gcd;
1054  }else{
1055  s->avctx->time_base= (AVRational){1001, 30000};
1056  }
1057  }
1058 
1059  if(s->custom_pcf){
1060  skip_bits(&s->gb, 2); //extended Temporal reference
1061  }
1062 
1063  if (ufep) {
1064  if (s->umvplus) {
1065  if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1066  skip_bits1(&s->gb);
1067  }
1068  if(s->h263_slice_structured){
1069  if (get_bits1(&s->gb) != 0) {
1070  av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1071  }
1072  if (get_bits1(&s->gb) != 0) {
1073  av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1074  }
1075  }
1076  }
1077 
1078  s->qscale = get_bits(&s->gb, 5);
1079  }
1080 
1081  if (s->width == 0 || s->height == 0) {
1082  av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1083  return -1;
1084  }
1085  s->mb_width = (s->width + 15) / 16;
1086  s->mb_height = (s->height + 15) / 16;
1087  s->mb_num = s->mb_width * s->mb_height;
1088 
1089  if (s->pb_frame) {
1090  skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1091  if (s->custom_pcf)
1092  skip_bits(&s->gb, 2); //extended Temporal reference
1093  skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1094  }
1095 
1096  if (s->pict_type!=AV_PICTURE_TYPE_B) {
1097  s->time = s->picture_number;
1098  s->pp_time = s->time - s->last_non_b_time;
1099  s->last_non_b_time = s->time;
1100  }else{
1101  s->time = s->picture_number;
1102  s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1103  if (s->pp_time <=s->pb_time ||
1104  s->pp_time <= s->pp_time - s->pb_time ||
1105  s->pp_time <= 0){
1106  s->pp_time = 2;
1107  s->pb_time = 1;
1108  }
1110  }
1111 
1112  /* PEI */
1113  while (get_bits1(&s->gb) != 0) {
1114  skip_bits(&s->gb, 8);
1115  }
1116 
1117  if(s->h263_slice_structured){
1118  if (get_bits1(&s->gb) != 1) {
1119  av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1120  return -1;
1121  }
1122 
1123  ff_h263_decode_mba(s);
1124 
1125  if (get_bits1(&s->gb) != 1) {
1126  av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1127  return -1;
1128  }
1129  }
1130  s->f_code = 1;
1131 
1132  if(s->h263_aic){
1133  s->y_dc_scale_table=
1135  }else{
1136  s->y_dc_scale_table=
1138  }
1139 
1141  if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1142  int i,j;
1143  for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1144  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1145  for(i=0; i<13; i++){
1146  for(j=0; j<3; j++){
1147  int v= get_bits(&s->gb, 8);
1148  v |= get_sbits(&s->gb, 8)<<8;
1149  av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1150  }
1151  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1152  }
1153  for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1154  }
1155 
1156  return 0;
1157 }