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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 #include <limits.h>
32 
33 #include "libavutil/attributes.h"
34 #include "libavutil/internal.h"
35 #include "libavutil/mathematics.h"
36 #include "avcodec.h"
37 #include "mpegvideo.h"
38 #include "h263.h"
39 #include "mathops.h"
40 #include "unary.h"
41 #include "flv.h"
42 #include "mpeg4video.h"
43 
44 // The defines below define the number of bits that are read at once for
45 // reading vlc values. Changing these may improve speed and data cache needs
46 // be aware though that decreasing them may need the number of stages that is
47 // passed to get_vlc* to be increased.
48 #define MV_VLC_BITS 9
49 #define H263_MBTYPE_B_VLC_BITS 6
50 #define CBPC_B_VLC_BITS 3
51 
52 static const int h263_mb_type_b_map[15]= {
65  0, //stuffing
68 };
69 
72  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",
74  s->gb.size_in_bits, 1-s->no_rounding,
75  s->obmc ? " AP" : "",
76  s->umvplus ? " UMV" : "",
77  s->h263_long_vectors ? " LONG" : "",
78  s->h263_plus ? " +" : "",
79  s->h263_aic ? " AIC" : "",
80  s->alt_inter_vlc ? " AIV" : "",
81  s->modified_quant ? " MQ" : "",
82  s->loop_filter ? " LOOP" : "",
83  s->h263_slice_structured ? " SS" : "",
85  );
86  }
87 }
88 
89 /***********************************************/
90 /* decoding */
91 
95 static VLC mv_vlc;
97 static VLC cbpc_b_vlc;
98 
99 /* init vlcs */
100 
101 /* XXX: find a better solution to handle static init */
103 {
104  static volatile int done = 0;
105 
106  if (!done) {
107  INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
109  ff_h263_intra_MCBPC_code, 1, 1, 72);
110  INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
112  ff_h263_inter_MCBPC_code, 1, 1, 198);
113  INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
114  &ff_h263_cbpy_tab[0][1], 2, 1,
115  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
116  INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
117  &ff_mvtab[0][1], 2, 1,
118  &ff_mvtab[0][0], 2, 1, 538);
123  INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
124  &ff_h263_mbtype_b_tab[0][1], 2, 1,
125  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
126  INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
127  &ff_cbpc_b_tab[0][1], 2, 1,
128  &ff_cbpc_b_tab[0][0], 2, 1, 8);
129  done = 1;
130  }
131 }
132 
134 {
135  int i, mb_pos;
136 
137  for(i=0; i<6; i++){
138  if(s->mb_num-1 <= ff_mba_max[i]) break;
139  }
140  mb_pos= get_bits(&s->gb, ff_mba_length[i]);
141  s->mb_x= mb_pos % s->mb_width;
142  s->mb_y= mb_pos / s->mb_width;
143 
144  return mb_pos;
145 }
146 
147 /**
148  * Decode the group of blocks header or slice header.
149  * @return <0 if an error occurred
150  */
152 {
153  unsigned int val, gob_number;
154  int left;
155 
156  /* Check for GOB Start Code */
157  val = show_bits(&s->gb, 16);
158  if(val)
159  return -1;
160 
161  /* We have a GBSC probably with GSTUFF */
162  skip_bits(&s->gb, 16); /* Drop the zeros */
163  left= get_bits_left(&s->gb);
164  //MN: we must check the bits left or we might end in a infinite loop (or segfault)
165  for(;left>13; left--){
166  if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
167  }
168  if(left<=13)
169  return -1;
170 
171  if(s->h263_slice_structured){
172  if(get_bits1(&s->gb)==0)
173  return -1;
174 
176 
177  if(s->mb_num > 1583)
178  if(get_bits1(&s->gb)==0)
179  return -1;
180 
181  s->qscale = get_bits(&s->gb, 5); /* SQUANT */
182  if(get_bits1(&s->gb)==0)
183  return -1;
184  skip_bits(&s->gb, 2); /* GFID */
185  }else{
186  gob_number = get_bits(&s->gb, 5); /* GN */
187  s->mb_x= 0;
188  s->mb_y= s->gob_index* gob_number;
189  skip_bits(&s->gb, 2); /* GFID */
190  s->qscale = get_bits(&s->gb, 5); /* GQUANT */
191  }
192 
193  if(s->mb_y >= s->mb_height)
194  return -1;
195 
196  if(s->qscale==0)
197  return -1;
198 
199  return 0;
200 }
201 
202 /**
203  * Find the next resync_marker.
204  * @param p pointer to buffer to scan
205  * @param end pointer to the end of the buffer
206  * @return pointer to the next resync_marker, or end if none was found
207  */
208 const uint8_t *ff_h263_find_resync_marker(MpegEncContext *s, const uint8_t *av_restrict p, const uint8_t *av_restrict end)
209 {
210  av_assert2(p < end);
211 
212  end-=2;
213  p++;
214  if(s->resync_marker){
215  int prefix_len = ff_mpeg4_get_video_packet_prefix_length(s);
216  for(;p<end; p+=2){
217  if(!*p){
218  if (!p[-1] && ((p[1] >> (23-prefix_len)) == 1)) return p - 1;
219  else if (!p[ 1] && ((p[2] >> (23-prefix_len)) == 1)) return p;
220  }
221  }
222  }
223  return end+2;
224 }
225 
226 /**
227  * Decode the group of blocks / video packet header.
228  * @return bit position of the resync_marker, or <0 if none was found
229  */
231  int left, pos, ret;
232 
233  if(s->codec_id==AV_CODEC_ID_MPEG4){
234  skip_bits1(&s->gb);
235  align_get_bits(&s->gb);
236  }
237 
238  if(show_bits(&s->gb, 16)==0){
239  pos= get_bits_count(&s->gb);
240  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
242  else
243  ret= h263_decode_gob_header(s);
244  if(ret>=0)
245  return pos;
246  }
247  //OK, it's not where it is supposed to be ...
248  s->gb= s->last_resync_gb;
249  align_get_bits(&s->gb);
250  left= get_bits_left(&s->gb);
251 
252  for(;left>16+1+5+5; left-=8){
253  if(show_bits(&s->gb, 16)==0){
254  GetBitContext bak= s->gb;
255 
256  pos= get_bits_count(&s->gb);
257  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
259  else
260  ret= h263_decode_gob_header(s);
261  if(ret>=0)
262  return pos;
263 
264  s->gb= bak;
265  }
266  skip_bits(&s->gb, 8);
267  }
268 
269  return -1;
270 }
271 
273 {
274  int code, val, sign, shift;
275  code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
276 
277  if (code == 0)
278  return pred;
279  if (code < 0)
280  return 0xffff;
281 
282  sign = get_bits1(&s->gb);
283  shift = f_code - 1;
284  val = code;
285  if (shift) {
286  val = (val - 1) << shift;
287  val |= get_bits(&s->gb, shift);
288  val++;
289  }
290  if (sign)
291  val = -val;
292  val += pred;
293 
294  /* modulo decoding */
295  if (!s->h263_long_vectors) {
296  val = sign_extend(val, 5 + f_code);
297  } else {
298  /* horrible h263 long vector mode */
299  if (pred < -31 && val < -63)
300  val += 64;
301  if (pred > 32 && val > 63)
302  val -= 64;
303 
304  }
305  return val;
306 }
307 
308 
309 /* Decode RVLC of H.263+ UMV */
311 {
312  int code = 0, sign;
313 
314  if (get_bits1(&s->gb)) /* Motion difference = 0 */
315  return pred;
316 
317  code = 2 + get_bits1(&s->gb);
318 
319  while (get_bits1(&s->gb))
320  {
321  code <<= 1;
322  code += get_bits1(&s->gb);
323  }
324  sign = code & 1;
325  code >>= 1;
326 
327  code = (sign) ? (pred - code) : (pred + code);
328  av_dlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
329  return code;
330 
331 }
332 
333 /**
334  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
335  */
337  GetBitContext gb= s->gb;
338 
339  int cbpc, i, pred_x, pred_y, mx, my;
340  int16_t *mot_val;
341  const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
342  const int stride= s->b8_stride*2;
343 
344  for(i=0; i<4; i++)
345  s->block_index[i]+= 2;
346  for(i=4; i<6; i++)
347  s->block_index[i]+= 1;
348  s->mb_x++;
349 
351 
352  do{
353  if (get_bits1(&s->gb)) {
354  /* skip mb */
355  mot_val = s->current_picture.motion_val[0][s->block_index[0]];
356  mot_val[0 ]= mot_val[2 ]=
357  mot_val[0+stride]= mot_val[2+stride]= 0;
358  mot_val[1 ]= mot_val[3 ]=
359  mot_val[1+stride]= mot_val[3+stride]= 0;
360 
362  goto end;
363  }
364  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
365  }while(cbpc == 20);
366 
367  if(cbpc & 4){
369  }else{
370  get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
371  if (cbpc & 8) {
372  if(s->modified_quant){
373  if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
374  else skip_bits(&s->gb, 5);
375  }else
376  skip_bits(&s->gb, 2);
377  }
378 
379  if ((cbpc & 16) == 0) {
381  /* 16x16 motion prediction */
382  mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
383  if (s->umvplus)
384  mx = h263p_decode_umotion(s, pred_x);
385  else
386  mx = ff_h263_decode_motion(s, pred_x, 1);
387 
388  if (s->umvplus)
389  my = h263p_decode_umotion(s, pred_y);
390  else
391  my = ff_h263_decode_motion(s, pred_y, 1);
392 
393  mot_val[0 ]= mot_val[2 ]=
394  mot_val[0+stride]= mot_val[2+stride]= mx;
395  mot_val[1 ]= mot_val[3 ]=
396  mot_val[1+stride]= mot_val[3+stride]= my;
397  } else {
399  for(i=0;i<4;i++) {
400  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
401  if (s->umvplus)
402  mx = h263p_decode_umotion(s, pred_x);
403  else
404  mx = ff_h263_decode_motion(s, pred_x, 1);
405 
406  if (s->umvplus)
407  my = h263p_decode_umotion(s, pred_y);
408  else
409  my = ff_h263_decode_motion(s, pred_y, 1);
410  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
411  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
412  mot_val[0] = mx;
413  mot_val[1] = my;
414  }
415  }
416  }
417 end:
418 
419  for(i=0; i<4; i++)
420  s->block_index[i]-= 2;
421  for(i=4; i<6; i++)
422  s->block_index[i]-= 1;
423  s->mb_x--;
424 
425  s->gb= gb;
426 }
427 
429  static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
430 
431  if(s->modified_quant){
432  if(get_bits1(&s->gb))
434  else
435  s->qscale= get_bits(&s->gb, 5);
436  }else
437  s->qscale += quant_tab[get_bits(&s->gb, 2)];
438  ff_set_qscale(s, s->qscale);
439 }
440 
441 static int h263_decode_block(MpegEncContext * s, int16_t * block,
442  int n, int coded)
443 {
444  int code, level, i, j, last, run;
445  RLTable *rl = &ff_h263_rl_inter;
446  const uint8_t *scan_table;
447  GetBitContext gb= s->gb;
448 
449  scan_table = s->intra_scantable.permutated;
450  if (s->h263_aic && s->mb_intra) {
451  rl = &ff_rl_intra_aic;
452  i = 0;
453  if (s->ac_pred) {
454  if (s->h263_aic_dir)
455  scan_table = s->intra_v_scantable.permutated; /* left */
456  else
457  scan_table = s->intra_h_scantable.permutated; /* top */
458  }
459  } else if (s->mb_intra) {
460  /* DC coef */
461  if(s->codec_id == AV_CODEC_ID_RV10){
462 #if CONFIG_RV10_DECODER
463  if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
464  int component, diff;
465  component = (n <= 3 ? 0 : n - 4 + 1);
466  level = s->last_dc[component];
467  if (s->rv10_first_dc_coded[component]) {
468  diff = ff_rv_decode_dc(s, n);
469  if (diff == 0xffff)
470  return -1;
471  level += diff;
472  level = level & 0xff; /* handle wrap round */
473  s->last_dc[component] = level;
474  } else {
475  s->rv10_first_dc_coded[component] = 1;
476  }
477  } else {
478  level = get_bits(&s->gb, 8);
479  if (level == 255)
480  level = 128;
481  }
482 #endif
483  }else{
484  level = get_bits(&s->gb, 8);
485  if((level&0x7F) == 0){
486  av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
488  return -1;
489  }
490  if (level == 255)
491  level = 128;
492  }
493  block[0] = level;
494  i = 1;
495  } else {
496  i = 0;
497  }
498  if (!coded) {
499  if (s->mb_intra && s->h263_aic)
500  goto not_coded;
501  s->block_last_index[n] = i - 1;
502  return 0;
503  }
504 retry:
505  for(;;) {
506  code = get_vlc2(&s->gb, rl->vlc.table, TEX_VLC_BITS, 2);
507  if (code < 0){
508  av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
509  return -1;
510  }
511  if (code == rl->n) {
512  /* escape */
513  if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
514  ff_flv2_decode_ac_esc(&s->gb, &level, &run, &last);
515  } else {
516  last = get_bits1(&s->gb);
517  run = get_bits(&s->gb, 6);
518  level = (int8_t)get_bits(&s->gb, 8);
519  if(level == -128){
520  if (s->codec_id == AV_CODEC_ID_RV10) {
521  /* XXX: should patch encoder too */
522  level = get_sbits(&s->gb, 12);
523  }else{
524  level = get_bits(&s->gb, 5);
525  level |= get_sbits(&s->gb, 6)<<5;
526  }
527  }
528  }
529  } else {
530  run = rl->table_run[code];
531  level = rl->table_level[code];
532  last = code >= rl->last;
533  if (get_bits1(&s->gb))
534  level = -level;
535  }
536  i += run;
537  if (i >= 64){
538  if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
539  //Looks like a hack but no, it's the way it is supposed to work ...
540  rl = &ff_rl_intra_aic;
541  i = 0;
542  s->gb= gb;
543  s->dsp.clear_block(block);
544  goto retry;
545  }
546  av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
547  return -1;
548  }
549  j = scan_table[i];
550  block[j] = level;
551  if (last)
552  break;
553  i++;
554  }
555 not_coded:
556  if (s->mb_intra && s->h263_aic) {
557  ff_h263_pred_acdc(s, block, n);
558  i = 63;
559  }
560  s->block_last_index[n] = i;
561  return 0;
562 }
563 
564 static int h263_skip_b_part(MpegEncContext *s, int cbp)
565 {
566  LOCAL_ALIGNED_16(int16_t, dblock, [64]);
567  int i, mbi;
568  int bli[6];
569 
570  /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
571  * but real value should be restored in order to be used later (in OBMC condition)
572  */
573  mbi = s->mb_intra;
574  memcpy(bli, s->block_last_index, sizeof(bli));
575  s->mb_intra = 0;
576  for (i = 0; i < 6; i++) {
577  if (h263_decode_block(s, dblock, i, cbp&32) < 0)
578  return -1;
579  cbp+=cbp;
580  }
581  s->mb_intra = mbi;
582  memcpy(s->block_last_index, bli, sizeof(bli));
583  return 0;
584 }
585 
586 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
587 {
588  int c, mv = 1;
589 
590  if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
591  c = get_bits1(gb);
592  if (pb_frame == 2 && c)
593  mv = !get_bits1(gb);
594  } else { // h.263 Annex M improved PB-frame
595  mv = get_unary(gb, 0, 4) + 1;
596  c = mv & 1;
597  mv = !!(mv & 2);
598  }
599  if(c)
600  *cbpb = get_bits(gb, 6);
601  return mv;
602 }
603 
605  int16_t block[6][64])
606 {
607  int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
608  int16_t *mot_val;
609  const int xy= s->mb_x + s->mb_y * s->mb_stride;
610  int cbpb = 0, pb_mv_count = 0;
611 
612  av_assert2(!s->h263_pred);
613 
614  if (s->pict_type == AV_PICTURE_TYPE_P) {
615  do{
616  if (get_bits1(&s->gb)) {
617  /* skip mb */
618  s->mb_intra = 0;
619  for(i=0;i<6;i++)
620  s->block_last_index[i] = -1;
621  s->mv_dir = MV_DIR_FORWARD;
622  s->mv_type = MV_TYPE_16X16;
624  s->mv[0][0][0] = 0;
625  s->mv[0][0][1] = 0;
626  s->mb_skipped = !(s->obmc | s->loop_filter);
627  goto end;
628  }
629  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
630  if (cbpc < 0){
631  av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
632  return -1;
633  }
634  }while(cbpc == 20);
635 
636  s->dsp.clear_blocks(s->block[0]);
637 
638  dquant = cbpc & 8;
639  s->mb_intra = ((cbpc & 4) != 0);
640  if (s->mb_intra) goto intra;
641 
642  if(s->pb_frame && get_bits1(&s->gb))
643  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
644  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
645 
646  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
647  cbpy ^= 0xF;
648 
649  cbp = (cbpc & 3) | (cbpy << 2);
650  if (dquant) {
652  }
653 
654  s->mv_dir = MV_DIR_FORWARD;
655  if ((cbpc & 16) == 0) {
657  /* 16x16 motion prediction */
658  s->mv_type = MV_TYPE_16X16;
659  ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
660  if (s->umvplus)
661  mx = h263p_decode_umotion(s, pred_x);
662  else
663  mx = ff_h263_decode_motion(s, pred_x, 1);
664 
665  if (mx >= 0xffff)
666  return -1;
667 
668  if (s->umvplus)
669  my = h263p_decode_umotion(s, pred_y);
670  else
671  my = ff_h263_decode_motion(s, pred_y, 1);
672 
673  if (my >= 0xffff)
674  return -1;
675  s->mv[0][0][0] = mx;
676  s->mv[0][0][1] = my;
677 
678  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
679  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
680  } else {
682  s->mv_type = MV_TYPE_8X8;
683  for(i=0;i<4;i++) {
684  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
685  if (s->umvplus)
686  mx = h263p_decode_umotion(s, pred_x);
687  else
688  mx = ff_h263_decode_motion(s, pred_x, 1);
689  if (mx >= 0xffff)
690  return -1;
691 
692  if (s->umvplus)
693  my = h263p_decode_umotion(s, pred_y);
694  else
695  my = ff_h263_decode_motion(s, pred_y, 1);
696  if (my >= 0xffff)
697  return -1;
698  s->mv[0][i][0] = mx;
699  s->mv[0][i][1] = my;
700  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
701  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
702  mot_val[0] = mx;
703  mot_val[1] = my;
704  }
705  }
706  } else if(s->pict_type==AV_PICTURE_TYPE_B) {
707  int mb_type;
708  const int stride= s->b8_stride;
709  int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
710  int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
711 // const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
712 
713  //FIXME ugly
714  mot_val0[0 ]= mot_val0[2 ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
715  mot_val0[1 ]= mot_val0[3 ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
716  mot_val1[0 ]= mot_val1[2 ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
717  mot_val1[1 ]= mot_val1[3 ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
718 
719  do{
720  mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
721  if (mb_type < 0){
722  av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
723  return -1;
724  }
725 
726  mb_type= h263_mb_type_b_map[ mb_type ];
727  }while(!mb_type);
728 
729  s->mb_intra = IS_INTRA(mb_type);
730  if(HAS_CBP(mb_type)){
731  s->dsp.clear_blocks(s->block[0]);
732  cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
733  if(s->mb_intra){
734  dquant = IS_QUANT(mb_type);
735  goto intra;
736  }
737 
738  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
739 
740  if (cbpy < 0){
741  av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
742  return -1;
743  }
744 
745  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
746  cbpy ^= 0xF;
747 
748  cbp = (cbpc & 3) | (cbpy << 2);
749  }else
750  cbp=0;
751 
752  av_assert2(!s->mb_intra);
753 
754  if(IS_QUANT(mb_type)){
756  }
757 
758  if(IS_DIRECT(mb_type)){
760  mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
761  }else{
762  s->mv_dir = 0;
764 //FIXME UMV
765 
766  if(USES_LIST(mb_type, 0)){
767  int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
768  s->mv_dir = MV_DIR_FORWARD;
769 
770  mx = ff_h263_decode_motion(s, mx, 1);
771  my = ff_h263_decode_motion(s, my, 1);
772 
773  s->mv[0][0][0] = mx;
774  s->mv[0][0][1] = my;
775  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
776  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
777  }
778 
779  if(USES_LIST(mb_type, 1)){
780  int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
781  s->mv_dir |= MV_DIR_BACKWARD;
782 
783  mx = ff_h263_decode_motion(s, mx, 1);
784  my = ff_h263_decode_motion(s, my, 1);
785 
786  s->mv[1][0][0] = mx;
787  s->mv[1][0][1] = my;
788  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
789  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
790  }
791  }
792 
793  s->current_picture.mb_type[xy] = mb_type;
794  } else { /* I-Frame */
795  do{
796  cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
797  if (cbpc < 0){
798  av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
799  return -1;
800  }
801  }while(cbpc == 8);
802 
803  s->dsp.clear_blocks(s->block[0]);
804 
805  dquant = cbpc & 4;
806  s->mb_intra = 1;
807 intra:
809  if (s->h263_aic) {
810  s->ac_pred = get_bits1(&s->gb);
811  if(s->ac_pred){
813 
814  s->h263_aic_dir = get_bits1(&s->gb);
815  }
816  }else
817  s->ac_pred = 0;
818 
819  if(s->pb_frame && get_bits1(&s->gb))
820  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
821  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
822  if(cbpy<0){
823  av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
824  return -1;
825  }
826  cbp = (cbpc & 3) | (cbpy << 2);
827  if (dquant) {
829  }
830 
831  pb_mv_count += !!s->pb_frame;
832  }
833 
834  while(pb_mv_count--){
835  ff_h263_decode_motion(s, 0, 1);
836  ff_h263_decode_motion(s, 0, 1);
837  }
838 
839  /* decode each block */
840  for (i = 0; i < 6; i++) {
841  if (h263_decode_block(s, block[i], i, cbp&32) < 0)
842  return -1;
843  cbp+=cbp;
844  }
845 
846  if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
847  return -1;
848  if(s->obmc && !s->mb_intra){
849  if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
850  preview_obmc(s);
851  }
852 end:
853 
854  /* per-MB end of slice check */
855  {
856  int v= show_bits(&s->gb, 16);
857 
858  if (get_bits_left(&s->gb) < 16) {
859  v >>= 16 - get_bits_left(&s->gb);
860  }
861 
862  if(v==0)
863  return SLICE_END;
864  }
865 
866  return SLICE_OK;
867 }
868 
869 /* most is hardcoded. should extend to handle all h263 streams */
871 {
872  int format, width, height, i;
873  uint32_t startcode;
874 
875  align_get_bits(&s->gb);
876 
877  if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
878  av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
879  }
880 
881  startcode= get_bits(&s->gb, 22-8);
882 
883  for(i= get_bits_left(&s->gb); i>24; i-=8) {
884  startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
885 
886  if(startcode == 0x20)
887  break;
888  }
889 
890  if (startcode != 0x20) {
891  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
892  return -1;
893  }
894  /* temporal reference */
895  i = get_bits(&s->gb, 8); /* picture timestamp */
896  if( (s->picture_number&~0xFF)+i < s->picture_number)
897  i+= 256;
899  s->picture_number= (s->picture_number&~0xFF) + i;
900 
901  /* PTYPE starts here */
902  if (get_bits1(&s->gb) != 1) {
903  /* marker */
904  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
905  return -1;
906  }
907  if (get_bits1(&s->gb) != 0) {
908  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
909  return -1; /* h263 id */
910  }
911  skip_bits1(&s->gb); /* split screen off */
912  skip_bits1(&s->gb); /* camera off */
913  skip_bits1(&s->gb); /* freeze picture release off */
914 
915  format = get_bits(&s->gb, 3);
916  /*
917  0 forbidden
918  1 sub-QCIF
919  10 QCIF
920  7 extended PTYPE (PLUSPTYPE)
921  */
922 
923  if (format != 7 && format != 6) {
924  s->h263_plus = 0;
925  /* H.263v1 */
926  width = ff_h263_format[format][0];
927  height = ff_h263_format[format][1];
928  if (!width)
929  return -1;
930 
932 
933  s->h263_long_vectors = get_bits1(&s->gb);
934 
935  if (get_bits1(&s->gb) != 0) {
936  av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
937  return -1; /* SAC: off */
938  }
939  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
940  s->unrestricted_mv = s->h263_long_vectors || s->obmc;
941 
942  s->pb_frame = get_bits1(&s->gb);
943  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
944  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
945 
946  s->width = width;
947  s->height = height;
948  s->avctx->sample_aspect_ratio= (AVRational){12,11};
949  s->avctx->time_base= (AVRational){1001, 30000};
950  } else {
951  int ufep;
952 
953  /* H.263v2 */
954  s->h263_plus = 1;
955  ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
956 
957  /* ufep other than 0 and 1 are reserved */
958  if (ufep == 1) {
959  /* OPPTYPE */
960  format = get_bits(&s->gb, 3);
961  av_dlog(s->avctx, "ufep=1, format: %d\n", format);
962  s->custom_pcf= get_bits1(&s->gb);
963  s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
964  if (get_bits1(&s->gb) != 0) {
965  av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
966  }
967  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
968  s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
969  s->loop_filter= get_bits1(&s->gb);
970  s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
971  if(s->avctx->lowres)
972  s->loop_filter = 0;
973 
975  if (get_bits1(&s->gb) != 0) {
976  av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
977  }
978  if (get_bits1(&s->gb) != 0) {
979  av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
980  }
981  s->alt_inter_vlc= get_bits1(&s->gb);
982  s->modified_quant= get_bits1(&s->gb);
983  if(s->modified_quant)
985 
986  skip_bits(&s->gb, 1); /* Prevent start code emulation */
987 
988  skip_bits(&s->gb, 3); /* Reserved */
989  } else if (ufep != 0) {
990  av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
991  return -1;
992  }
993 
994  /* MPPTYPE */
995  s->pict_type = get_bits(&s->gb, 3);
996  switch(s->pict_type){
997  case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
998  case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
999  case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
1000  case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
1001  case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
1002  default:
1003  return -1;
1004  }
1005  skip_bits(&s->gb, 2);
1006  s->no_rounding = get_bits1(&s->gb);
1007  skip_bits(&s->gb, 4);
1008 
1009  /* Get the picture dimensions */
1010  if (ufep) {
1011  if (format == 6) {
1012  /* Custom Picture Format (CPFMT) */
1013  s->aspect_ratio_info = get_bits(&s->gb, 4);
1014  av_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1015  /* aspect ratios:
1016  0 - forbidden
1017  1 - 1:1
1018  2 - 12:11 (CIF 4:3)
1019  3 - 10:11 (525-type 4:3)
1020  4 - 16:11 (CIF 16:9)
1021  5 - 40:33 (525-type 16:9)
1022  6-14 - reserved
1023  */
1024  width = (get_bits(&s->gb, 9) + 1) * 4;
1025  skip_bits1(&s->gb);
1026  height = get_bits(&s->gb, 9) * 4;
1027  av_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1029  /* aspected dimensions */
1030  s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1031  s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1032  }else{
1034  }
1035  } else {
1036  width = ff_h263_format[format][0];
1037  height = ff_h263_format[format][1];
1038  s->avctx->sample_aspect_ratio= (AVRational){12,11};
1039  }
1041  if ((width == 0) || (height == 0))
1042  return -1;
1043  s->width = width;
1044  s->height = height;
1045 
1046  if(s->custom_pcf){
1047  int gcd;
1048  s->avctx->time_base.den= 1800000;
1049  s->avctx->time_base.num= 1000 + get_bits1(&s->gb);
1050  s->avctx->time_base.num*= get_bits(&s->gb, 7);
1051  if(s->avctx->time_base.num == 0){
1052  av_log(s, AV_LOG_ERROR, "zero framerate\n");
1053  return -1;
1054  }
1055  gcd= av_gcd(s->avctx->time_base.den, s->avctx->time_base.num);
1056  s->avctx->time_base.den /= gcd;
1057  s->avctx->time_base.num /= gcd;
1058  }else{
1059  s->avctx->time_base= (AVRational){1001, 30000};
1060  }
1061  }
1062 
1063  if(s->custom_pcf){
1064  skip_bits(&s->gb, 2); //extended Temporal reference
1065  }
1066 
1067  if (ufep) {
1068  if (s->umvplus) {
1069  if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1070  skip_bits1(&s->gb);
1071  }
1072  if(s->h263_slice_structured){
1073  if (get_bits1(&s->gb) != 0) {
1074  av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1075  }
1076  if (get_bits1(&s->gb) != 0) {
1077  av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1078  }
1079  }
1080  }
1081 
1082  s->qscale = get_bits(&s->gb, 5);
1083  }
1084 
1085  if (s->width == 0 || s->height == 0) {
1086  av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1087  return -1;
1088  }
1089  s->mb_width = (s->width + 15) / 16;
1090  s->mb_height = (s->height + 15) / 16;
1091  s->mb_num = s->mb_width * s->mb_height;
1092 
1093  if (s->pb_frame) {
1094  skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1095  if (s->custom_pcf)
1096  skip_bits(&s->gb, 2); //extended Temporal reference
1097  skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1098  }
1099 
1100  if (s->pict_type!=AV_PICTURE_TYPE_B) {
1101  s->time = s->picture_number;
1102  s->pp_time = s->time - s->last_non_b_time;
1103  s->last_non_b_time = s->time;
1104  }else{
1105  s->time = s->picture_number;
1106  s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1107  if (s->pp_time <=s->pb_time ||
1108  s->pp_time <= s->pp_time - s->pb_time ||
1109  s->pp_time <= 0){
1110  s->pp_time = 2;
1111  s->pb_time = 1;
1112  }
1114  }
1115 
1116  /* PEI */
1117  while (get_bits1(&s->gb) != 0) {
1118  skip_bits(&s->gb, 8);
1119  }
1120 
1121  if(s->h263_slice_structured){
1122  if (get_bits1(&s->gb) != 1) {
1123  av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1124  return -1;
1125  }
1126 
1127  ff_h263_decode_mba(s);
1128 
1129  if (get_bits1(&s->gb) != 1) {
1130  av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1131  return -1;
1132  }
1133  }
1134  s->f_code = 1;
1135 
1136  if(s->h263_aic){
1137  s->y_dc_scale_table=
1139  }else{
1140  s->y_dc_scale_table=
1142  }
1143 
1145  if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1146  int i,j;
1147  for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1148  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1149  for(i=0; i<13; i++){
1150  for(j=0; j<3; j++){
1151  int v= get_bits(&s->gb, 8);
1152  v |= get_sbits(&s->gb, 8)<<8;
1153  av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1154  }
1155  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1156  }
1157  for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1158  }
1159 
1160  return 0;
1161 }