FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
ituh263dec.c
Go to the documentation of this file.
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 "mpegutils.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  * Decode the group of blocks / video packet header.
205  * @return bit position of the resync_marker, or <0 if none was found
206  */
208  int left, pos, ret;
209 
210  if(s->codec_id==AV_CODEC_ID_MPEG4){
211  skip_bits1(&s->gb);
212  align_get_bits(&s->gb);
213  }
214 
215  if(show_bits(&s->gb, 16)==0){
216  pos= get_bits_count(&s->gb);
217  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
219  else
220  ret= h263_decode_gob_header(s);
221  if(ret>=0)
222  return pos;
223  }
224  //OK, it's not where it is supposed to be ...
225  s->gb= s->last_resync_gb;
226  align_get_bits(&s->gb);
227  left= get_bits_left(&s->gb);
228 
229  for(;left>16+1+5+5; left-=8){
230  if(show_bits(&s->gb, 16)==0){
231  GetBitContext bak= s->gb;
232 
233  pos= get_bits_count(&s->gb);
234  if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
236  else
237  ret= h263_decode_gob_header(s);
238  if(ret>=0)
239  return pos;
240 
241  s->gb= bak;
242  }
243  skip_bits(&s->gb, 8);
244  }
245 
246  return -1;
247 }
248 
250 {
251  int code, val, sign, shift;
252  code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
253 
254  if (code == 0)
255  return pred;
256  if (code < 0)
257  return 0xffff;
258 
259  sign = get_bits1(&s->gb);
260  shift = f_code - 1;
261  val = code;
262  if (shift) {
263  val = (val - 1) << shift;
264  val |= get_bits(&s->gb, shift);
265  val++;
266  }
267  if (sign)
268  val = -val;
269  val += pred;
270 
271  /* modulo decoding */
272  if (!s->h263_long_vectors) {
273  val = sign_extend(val, 5 + f_code);
274  } else {
275  /* horrible h263 long vector mode */
276  if (pred < -31 && val < -63)
277  val += 64;
278  if (pred > 32 && val > 63)
279  val -= 64;
280 
281  }
282  return val;
283 }
284 
285 
286 /* Decode RVLC of H.263+ UMV */
288 {
289  int code = 0, sign;
290 
291  if (get_bits1(&s->gb)) /* Motion difference = 0 */
292  return pred;
293 
294  code = 2 + get_bits1(&s->gb);
295 
296  while (get_bits1(&s->gb))
297  {
298  code <<= 1;
299  code += get_bits1(&s->gb);
300  }
301  sign = code & 1;
302  code >>= 1;
303 
304  code = (sign) ? (pred - code) : (pred + code);
305  av_dlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
306  return code;
307 
308 }
309 
310 /**
311  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
312  */
314  GetBitContext gb= s->gb;
315 
316  int cbpc, i, pred_x, pred_y, mx, my;
317  int16_t *mot_val;
318  const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
319  const int stride= s->b8_stride*2;
320 
321  for(i=0; i<4; i++)
322  s->block_index[i]+= 2;
323  for(i=4; i<6; i++)
324  s->block_index[i]+= 1;
325  s->mb_x++;
326 
328 
329  do{
330  if (get_bits1(&s->gb)) {
331  /* skip mb */
332  mot_val = s->current_picture.motion_val[0][s->block_index[0]];
333  mot_val[0 ]= mot_val[2 ]=
334  mot_val[0+stride]= mot_val[2+stride]= 0;
335  mot_val[1 ]= mot_val[3 ]=
336  mot_val[1+stride]= mot_val[3+stride]= 0;
337 
339  goto end;
340  }
341  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
342  }while(cbpc == 20);
343 
344  if(cbpc & 4){
346  }else{
347  get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
348  if (cbpc & 8) {
349  if(s->modified_quant){
350  if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
351  else skip_bits(&s->gb, 5);
352  }else
353  skip_bits(&s->gb, 2);
354  }
355 
356  if ((cbpc & 16) == 0) {
358  /* 16x16 motion prediction */
359  mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
360  if (s->umvplus)
361  mx = h263p_decode_umotion(s, pred_x);
362  else
363  mx = ff_h263_decode_motion(s, pred_x, 1);
364 
365  if (s->umvplus)
366  my = h263p_decode_umotion(s, pred_y);
367  else
368  my = ff_h263_decode_motion(s, pred_y, 1);
369 
370  mot_val[0 ]= mot_val[2 ]=
371  mot_val[0+stride]= mot_val[2+stride]= mx;
372  mot_val[1 ]= mot_val[3 ]=
373  mot_val[1+stride]= mot_val[3+stride]= my;
374  } else {
376  for(i=0;i<4;i++) {
377  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
378  if (s->umvplus)
379  mx = h263p_decode_umotion(s, pred_x);
380  else
381  mx = ff_h263_decode_motion(s, pred_x, 1);
382 
383  if (s->umvplus)
384  my = h263p_decode_umotion(s, pred_y);
385  else
386  my = ff_h263_decode_motion(s, pred_y, 1);
387  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
388  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
389  mot_val[0] = mx;
390  mot_val[1] = my;
391  }
392  }
393  }
394 end:
395 
396  for(i=0; i<4; i++)
397  s->block_index[i]-= 2;
398  for(i=4; i<6; i++)
399  s->block_index[i]-= 1;
400  s->mb_x--;
401 
402  s->gb= gb;
403 }
404 
406  static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
407 
408  if(s->modified_quant){
409  if(get_bits1(&s->gb))
411  else
412  s->qscale= get_bits(&s->gb, 5);
413  }else
414  s->qscale += quant_tab[get_bits(&s->gb, 2)];
415  ff_set_qscale(s, s->qscale);
416 }
417 
418 static int h263_decode_block(MpegEncContext * s, int16_t * block,
419  int n, int coded)
420 {
421  int code, level, i, j, last, run;
422  RLTable *rl = &ff_h263_rl_inter;
423  const uint8_t *scan_table;
424  GetBitContext gb= s->gb;
425 
426  scan_table = s->intra_scantable.permutated;
427  if (s->h263_aic && s->mb_intra) {
428  rl = &ff_rl_intra_aic;
429  i = 0;
430  if (s->ac_pred) {
431  if (s->h263_aic_dir)
432  scan_table = s->intra_v_scantable.permutated; /* left */
433  else
434  scan_table = s->intra_h_scantable.permutated; /* top */
435  }
436  } else if (s->mb_intra) {
437  /* DC coef */
438  if(s->codec_id == AV_CODEC_ID_RV10){
439 #if CONFIG_RV10_DECODER
440  if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
441  int component, diff;
442  component = (n <= 3 ? 0 : n - 4 + 1);
443  level = s->last_dc[component];
444  if (s->rv10_first_dc_coded[component]) {
445  diff = ff_rv_decode_dc(s, n);
446  if (diff == 0xffff)
447  return -1;
448  level += diff;
449  level = level & 0xff; /* handle wrap round */
450  s->last_dc[component] = level;
451  } else {
452  s->rv10_first_dc_coded[component] = 1;
453  }
454  } else {
455  level = get_bits(&s->gb, 8);
456  if (level == 255)
457  level = 128;
458  }
459 #endif
460  }else{
461  level = get_bits(&s->gb, 8);
462  if((level&0x7F) == 0){
463  av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
465  return -1;
466  }
467  if (level == 255)
468  level = 128;
469  }
470  block[0] = level;
471  i = 1;
472  } else {
473  i = 0;
474  }
475  if (!coded) {
476  if (s->mb_intra && s->h263_aic)
477  goto not_coded;
478  s->block_last_index[n] = i - 1;
479  return 0;
480  }
481 retry:
482  for(;;) {
483  code = get_vlc2(&s->gb, rl->vlc.table, TEX_VLC_BITS, 2);
484  if (code < 0){
485  av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
486  return -1;
487  }
488  if (code == rl->n) {
489  /* escape */
490  if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
491  ff_flv2_decode_ac_esc(&s->gb, &level, &run, &last);
492  } else {
493  last = get_bits1(&s->gb);
494  run = get_bits(&s->gb, 6);
495  level = (int8_t)get_bits(&s->gb, 8);
496  if(level == -128){
497  if (s->codec_id == AV_CODEC_ID_RV10) {
498  /* XXX: should patch encoder too */
499  level = get_sbits(&s->gb, 12);
500  }else{
501  level = get_bits(&s->gb, 5);
502  level |= get_sbits(&s->gb, 6)<<5;
503  }
504  }
505  }
506  } else {
507  run = rl->table_run[code];
508  level = rl->table_level[code];
509  last = code >= rl->last;
510  if (get_bits1(&s->gb))
511  level = -level;
512  }
513  i += run;
514  if (i >= 64){
515  if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
516  //Looks like a hack but no, it's the way it is supposed to work ...
517  rl = &ff_rl_intra_aic;
518  i = 0;
519  s->gb= gb;
520  s->bdsp.clear_block(block);
521  goto retry;
522  }
523  av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
524  return -1;
525  }
526  j = scan_table[i];
527  block[j] = level;
528  if (last)
529  break;
530  i++;
531  }
532 not_coded:
533  if (s->mb_intra && s->h263_aic) {
534  ff_h263_pred_acdc(s, block, n);
535  i = 63;
536  }
537  s->block_last_index[n] = i;
538  return 0;
539 }
540 
541 static int h263_skip_b_part(MpegEncContext *s, int cbp)
542 {
543  LOCAL_ALIGNED_16(int16_t, dblock, [64]);
544  int i, mbi;
545  int bli[6];
546 
547  /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
548  * but real value should be restored in order to be used later (in OBMC condition)
549  */
550  mbi = s->mb_intra;
551  memcpy(bli, s->block_last_index, sizeof(bli));
552  s->mb_intra = 0;
553  for (i = 0; i < 6; i++) {
554  if (h263_decode_block(s, dblock, i, cbp&32) < 0)
555  return -1;
556  cbp+=cbp;
557  }
558  s->mb_intra = mbi;
559  memcpy(s->block_last_index, bli, sizeof(bli));
560  return 0;
561 }
562 
563 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
564 {
565  int c, mv = 1;
566 
567  if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
568  c = get_bits1(gb);
569  if (pb_frame == 2 && c)
570  mv = !get_bits1(gb);
571  } else { // h.263 Annex M improved PB-frame
572  mv = get_unary(gb, 0, 4) + 1;
573  c = mv & 1;
574  mv = !!(mv & 2);
575  }
576  if(c)
577  *cbpb = get_bits(gb, 6);
578  return mv;
579 }
580 
582  int16_t block[6][64])
583 {
584  int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
585  int16_t *mot_val;
586  const int xy= s->mb_x + s->mb_y * s->mb_stride;
587  int cbpb = 0, pb_mv_count = 0;
588 
589  av_assert2(!s->h263_pred);
590 
591  if (s->pict_type == AV_PICTURE_TYPE_P) {
592  do{
593  if (get_bits1(&s->gb)) {
594  /* skip mb */
595  s->mb_intra = 0;
596  for(i=0;i<6;i++)
597  s->block_last_index[i] = -1;
598  s->mv_dir = MV_DIR_FORWARD;
599  s->mv_type = MV_TYPE_16X16;
601  s->mv[0][0][0] = 0;
602  s->mv[0][0][1] = 0;
603  s->mb_skipped = !(s->obmc | s->loop_filter);
604  goto end;
605  }
606  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
607  if (cbpc < 0){
608  av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
609  return -1;
610  }
611  }while(cbpc == 20);
612 
613  s->bdsp.clear_blocks(s->block[0]);
614 
615  dquant = cbpc & 8;
616  s->mb_intra = ((cbpc & 4) != 0);
617  if (s->mb_intra) goto intra;
618 
619  if(s->pb_frame && get_bits1(&s->gb))
620  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
621  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
622 
623  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
624  cbpy ^= 0xF;
625 
626  cbp = (cbpc & 3) | (cbpy << 2);
627  if (dquant) {
629  }
630 
631  s->mv_dir = MV_DIR_FORWARD;
632  if ((cbpc & 16) == 0) {
634  /* 16x16 motion prediction */
635  s->mv_type = MV_TYPE_16X16;
636  ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
637  if (s->umvplus)
638  mx = h263p_decode_umotion(s, pred_x);
639  else
640  mx = ff_h263_decode_motion(s, pred_x, 1);
641 
642  if (mx >= 0xffff)
643  return -1;
644 
645  if (s->umvplus)
646  my = h263p_decode_umotion(s, pred_y);
647  else
648  my = ff_h263_decode_motion(s, pred_y, 1);
649 
650  if (my >= 0xffff)
651  return -1;
652  s->mv[0][0][0] = mx;
653  s->mv[0][0][1] = my;
654 
655  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
656  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
657  } else {
659  s->mv_type = MV_TYPE_8X8;
660  for(i=0;i<4;i++) {
661  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
662  if (s->umvplus)
663  mx = h263p_decode_umotion(s, pred_x);
664  else
665  mx = ff_h263_decode_motion(s, pred_x, 1);
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  if (my >= 0xffff)
674  return -1;
675  s->mv[0][i][0] = mx;
676  s->mv[0][i][1] = my;
677  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
678  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
679  mot_val[0] = mx;
680  mot_val[1] = my;
681  }
682  }
683  } else if(s->pict_type==AV_PICTURE_TYPE_B) {
684  int mb_type;
685  const int stride= s->b8_stride;
686  int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
687  int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
688 // const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
689 
690  //FIXME ugly
691  mot_val0[0 ]= mot_val0[2 ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
692  mot_val0[1 ]= mot_val0[3 ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
693  mot_val1[0 ]= mot_val1[2 ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
694  mot_val1[1 ]= mot_val1[3 ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
695 
696  do{
697  mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
698  if (mb_type < 0){
699  av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
700  return -1;
701  }
702 
703  mb_type= h263_mb_type_b_map[ mb_type ];
704  }while(!mb_type);
705 
706  s->mb_intra = IS_INTRA(mb_type);
707  if(HAS_CBP(mb_type)){
708  s->bdsp.clear_blocks(s->block[0]);
709  cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
710  if(s->mb_intra){
711  dquant = IS_QUANT(mb_type);
712  goto intra;
713  }
714 
715  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
716 
717  if (cbpy < 0){
718  av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
719  return -1;
720  }
721 
722  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
723  cbpy ^= 0xF;
724 
725  cbp = (cbpc & 3) | (cbpy << 2);
726  }else
727  cbp=0;
728 
729  av_assert2(!s->mb_intra);
730 
731  if(IS_QUANT(mb_type)){
733  }
734 
735  if(IS_DIRECT(mb_type)){
737  mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
738  }else{
739  s->mv_dir = 0;
741 //FIXME UMV
742 
743  if(USES_LIST(mb_type, 0)){
744  int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
745  s->mv_dir = MV_DIR_FORWARD;
746 
747  mx = ff_h263_decode_motion(s, mx, 1);
748  my = ff_h263_decode_motion(s, my, 1);
749 
750  s->mv[0][0][0] = mx;
751  s->mv[0][0][1] = my;
752  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
753  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
754  }
755 
756  if(USES_LIST(mb_type, 1)){
757  int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
758  s->mv_dir |= MV_DIR_BACKWARD;
759 
760  mx = ff_h263_decode_motion(s, mx, 1);
761  my = ff_h263_decode_motion(s, my, 1);
762 
763  s->mv[1][0][0] = mx;
764  s->mv[1][0][1] = my;
765  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
766  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
767  }
768  }
769 
770  s->current_picture.mb_type[xy] = mb_type;
771  } else { /* I-Frame */
772  do{
773  cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
774  if (cbpc < 0){
775  av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
776  return -1;
777  }
778  }while(cbpc == 8);
779 
780  s->bdsp.clear_blocks(s->block[0]);
781 
782  dquant = cbpc & 4;
783  s->mb_intra = 1;
784 intra:
786  if (s->h263_aic) {
787  s->ac_pred = get_bits1(&s->gb);
788  if(s->ac_pred){
790 
791  s->h263_aic_dir = get_bits1(&s->gb);
792  }
793  }else
794  s->ac_pred = 0;
795 
796  if(s->pb_frame && get_bits1(&s->gb))
797  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
798  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
799  if(cbpy<0){
800  av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
801  return -1;
802  }
803  cbp = (cbpc & 3) | (cbpy << 2);
804  if (dquant) {
806  }
807 
808  pb_mv_count += !!s->pb_frame;
809  }
810 
811  while(pb_mv_count--){
812  ff_h263_decode_motion(s, 0, 1);
813  ff_h263_decode_motion(s, 0, 1);
814  }
815 
816  /* decode each block */
817  for (i = 0; i < 6; i++) {
818  if (h263_decode_block(s, block[i], i, cbp&32) < 0)
819  return -1;
820  cbp+=cbp;
821  }
822 
823  if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
824  return -1;
825  if(s->obmc && !s->mb_intra){
826  if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
827  preview_obmc(s);
828  }
829 end:
830 
831  /* per-MB end of slice check */
832  {
833  int v= show_bits(&s->gb, 16);
834 
835  if (get_bits_left(&s->gb) < 16) {
836  v >>= 16 - get_bits_left(&s->gb);
837  }
838 
839  if(v==0)
840  return SLICE_END;
841  }
842 
843  return SLICE_OK;
844 }
845 
846 /* most is hardcoded. should extend to handle all h263 streams */
848 {
849  int format, width, height, i;
850  uint32_t startcode;
851 
852  align_get_bits(&s->gb);
853 
854  if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
855  av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
856  }
857 
858  startcode= get_bits(&s->gb, 22-8);
859 
860  for(i= get_bits_left(&s->gb); i>24; i-=8) {
861  startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
862 
863  if(startcode == 0x20)
864  break;
865  }
866 
867  if (startcode != 0x20) {
868  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
869  return -1;
870  }
871  /* temporal reference */
872  i = get_bits(&s->gb, 8); /* picture timestamp */
873  if( (s->picture_number&~0xFF)+i < s->picture_number)
874  i+= 256;
875  s->picture_number= (s->picture_number&~0xFF) + i;
876 
877  /* PTYPE starts here */
878  if (get_bits1(&s->gb) != 1) {
879  /* marker */
880  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
881  return -1;
882  }
883  if (get_bits1(&s->gb) != 0) {
884  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
885  return -1; /* h263 id */
886  }
887  skip_bits1(&s->gb); /* split screen off */
888  skip_bits1(&s->gb); /* camera off */
889  skip_bits1(&s->gb); /* freeze picture release off */
890 
891  format = get_bits(&s->gb, 3);
892  /*
893  0 forbidden
894  1 sub-QCIF
895  10 QCIF
896  7 extended PTYPE (PLUSPTYPE)
897  */
898 
899  if (format != 7 && format != 6) {
900  s->h263_plus = 0;
901  /* H.263v1 */
902  width = ff_h263_format[format][0];
903  height = ff_h263_format[format][1];
904  if (!width)
905  return -1;
906 
908 
909  s->h263_long_vectors = get_bits1(&s->gb);
910 
911  if (get_bits1(&s->gb) != 0) {
912  av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
913  return -1; /* SAC: off */
914  }
915  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
916  s->unrestricted_mv = s->h263_long_vectors || s->obmc;
917 
918  s->pb_frame = get_bits1(&s->gb);
919  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
920  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
921 
922  s->width = width;
923  s->height = height;
924  s->avctx->sample_aspect_ratio= (AVRational){12,11};
925  s->avctx->time_base= (AVRational){1001, 30000};
926  } else {
927  int ufep;
928 
929  /* H.263v2 */
930  s->h263_plus = 1;
931  ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
932 
933  /* ufep other than 0 and 1 are reserved */
934  if (ufep == 1) {
935  /* OPPTYPE */
936  format = get_bits(&s->gb, 3);
937  av_dlog(s->avctx, "ufep=1, format: %d\n", format);
938  s->custom_pcf= get_bits1(&s->gb);
939  s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
940  if (get_bits1(&s->gb) != 0) {
941  av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
942  }
943  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
944  s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
945  s->loop_filter= get_bits1(&s->gb);
946  s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
947  if(s->avctx->lowres)
948  s->loop_filter = 0;
949 
951  if (get_bits1(&s->gb) != 0) {
952  av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
953  }
954  if (get_bits1(&s->gb) != 0) {
955  av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
956  }
957  s->alt_inter_vlc= get_bits1(&s->gb);
958  s->modified_quant= get_bits1(&s->gb);
959  if(s->modified_quant)
961 
962  skip_bits(&s->gb, 1); /* Prevent start code emulation */
963 
964  skip_bits(&s->gb, 3); /* Reserved */
965  } else if (ufep != 0) {
966  av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
967  return -1;
968  }
969 
970  /* MPPTYPE */
971  s->pict_type = get_bits(&s->gb, 3);
972  switch(s->pict_type){
973  case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
974  case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
975  case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
976  case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
977  case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
978  default:
979  return -1;
980  }
981  skip_bits(&s->gb, 2);
982  s->no_rounding = get_bits1(&s->gb);
983  skip_bits(&s->gb, 4);
984 
985  /* Get the picture dimensions */
986  if (ufep) {
987  if (format == 6) {
988  /* Custom Picture Format (CPFMT) */
989  s->aspect_ratio_info = get_bits(&s->gb, 4);
990  av_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
991  /* aspect ratios:
992  0 - forbidden
993  1 - 1:1
994  2 - 12:11 (CIF 4:3)
995  3 - 10:11 (525-type 4:3)
996  4 - 16:11 (CIF 16:9)
997  5 - 40:33 (525-type 16:9)
998  6-14 - reserved
999  */
1000  width = (get_bits(&s->gb, 9) + 1) * 4;
1001  skip_bits1(&s->gb);
1002  height = get_bits(&s->gb, 9) * 4;
1003  av_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1005  /* aspected dimensions */
1006  s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1007  s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1008  }else{
1010  }
1011  } else {
1012  width = ff_h263_format[format][0];
1013  height = ff_h263_format[format][1];
1014  s->avctx->sample_aspect_ratio= (AVRational){12,11};
1015  }
1017  if ((width == 0) || (height == 0))
1018  return -1;
1019  s->width = width;
1020  s->height = height;
1021 
1022  if(s->custom_pcf){
1023  int gcd;
1024  s->avctx->time_base.den= 1800000;
1025  s->avctx->time_base.num= 1000 + get_bits1(&s->gb);
1026  s->avctx->time_base.num*= get_bits(&s->gb, 7);
1027  if(s->avctx->time_base.num == 0){
1028  av_log(s, AV_LOG_ERROR, "zero framerate\n");
1029  return -1;
1030  }
1031  gcd= av_gcd(s->avctx->time_base.den, s->avctx->time_base.num);
1032  s->avctx->time_base.den /= gcd;
1033  s->avctx->time_base.num /= gcd;
1034  }else{
1035  s->avctx->time_base= (AVRational){1001, 30000};
1036  }
1037  }
1038 
1039  if(s->custom_pcf){
1040  skip_bits(&s->gb, 2); //extended Temporal reference
1041  }
1042 
1043  if (ufep) {
1044  if (s->umvplus) {
1045  if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1046  skip_bits1(&s->gb);
1047  }
1048  if(s->h263_slice_structured){
1049  if (get_bits1(&s->gb) != 0) {
1050  av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1051  }
1052  if (get_bits1(&s->gb) != 0) {
1053  av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1054  }
1055  }
1056  }
1057 
1058  s->qscale = get_bits(&s->gb, 5);
1059  }
1060 
1061  if (s->width == 0 || s->height == 0) {
1062  av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1063  return -1;
1064  }
1065  s->mb_width = (s->width + 15) / 16;
1066  s->mb_height = (s->height + 15) / 16;
1067  s->mb_num = s->mb_width * s->mb_height;
1068 
1069  if (s->pb_frame) {
1070  skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1071  if (s->custom_pcf)
1072  skip_bits(&s->gb, 2); //extended Temporal reference
1073  skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1074  }
1075 
1076  if (s->pict_type!=AV_PICTURE_TYPE_B) {
1077  s->time = s->picture_number;
1078  s->pp_time = s->time - s->last_non_b_time;
1079  s->last_non_b_time = s->time;
1080  }else{
1081  s->time = s->picture_number;
1082  s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1083  if (s->pp_time <=s->pb_time ||
1084  s->pp_time <= s->pp_time - s->pb_time ||
1085  s->pp_time <= 0){
1086  s->pp_time = 2;
1087  s->pb_time = 1;
1088  }
1090  }
1091 
1092  /* PEI */
1093  if (skip_1stop_8data_bits(&s->gb) < 0)
1094  return AVERROR_INVALIDDATA;
1095 
1096  if(s->h263_slice_structured){
1097  if (get_bits1(&s->gb) != 1) {
1098  av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1099  return -1;
1100  }
1101 
1102  ff_h263_decode_mba(s);
1103 
1104  if (get_bits1(&s->gb) != 1) {
1105  av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1106  return -1;
1107  }
1108  }
1109  s->f_code = 1;
1110 
1111  if(s->h263_aic){
1112  s->y_dc_scale_table=
1114  }else{
1115  s->y_dc_scale_table=
1117  }
1118 
1120  if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1121  int i,j;
1122  for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1123  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1124  for(i=0; i<13; i++){
1125  for(j=0; j<3; j++){
1126  int v= get_bits(&s->gb, 8);
1127  v |= get_sbits(&s->gb, 8)<<8;
1128  av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1129  }
1130  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1131  }
1132  for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1133  }
1134 
1135  return 0;
1136 }