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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 "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]= {
54  MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
55  MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
56  MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
57  MB_TYPE_L0 | MB_TYPE_16x16,
58  MB_TYPE_L0 | MB_TYPE_CBP | MB_TYPE_16x16,
59  MB_TYPE_L0 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
60  MB_TYPE_L1 | MB_TYPE_16x16,
61  MB_TYPE_L1 | MB_TYPE_CBP | MB_TYPE_16x16,
62  MB_TYPE_L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
63  MB_TYPE_L0L1 | MB_TYPE_16x16,
64  MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_16x16,
65  MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
66  0, //stuffing
67  MB_TYPE_INTRA4x4 | MB_TYPE_CBP,
68  MB_TYPE_INTRA4x4 | MB_TYPE_CBP | MB_TYPE_QUANT,
69 };
70 
71 void ff_h263_show_pict_info(MpegEncContext *s){
72  if(s->avctx->debug&FF_DEBUG_PICT_INFO){
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",
74  s->qscale, av_get_picture_type_char(s->pict_type),
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" : "",
85  s->avctx->framerate.num, s->avctx->framerate.den
86  );
87  }
88 }
89 
90 /***********************************************/
91 /* decoding */
92 
93 VLC ff_h263_intra_MCBPC_vlc;
94 VLC ff_h263_inter_MCBPC_vlc;
95 VLC ff_h263_cbpy_vlc;
96 static VLC mv_vlc;
97 static VLC h263_mbtype_b_vlc;
98 static VLC cbpc_b_vlc;
99 
100 /* init vlcs */
101 
102 /* XXX: find a better solution to handle static init */
103 av_cold void ff_h263_decode_init_vlc(void)
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,
109  ff_h263_intra_MCBPC_bits, 1, 1,
110  ff_h263_intra_MCBPC_code, 1, 1, 72);
111  INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
112  ff_h263_inter_MCBPC_bits, 1, 1,
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);
120  ff_init_rl(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
121  ff_init_rl(&ff_rl_intra_aic, ff_h263_static_rl_table_store[1]);
122  INIT_VLC_RL(ff_h263_rl_inter, 554);
123  INIT_VLC_RL(ff_rl_intra_aic, 554);
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 
134 int ff_h263_decode_mba(MpegEncContext *s)
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  */
152 static int h263_decode_gob_header(MpegEncContext *s)
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 
176  ff_h263_decode_mba(s);
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  */
207 int ff_h263_resync(MpegEncContext *s){
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)
218  ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
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)
235  ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
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 
249 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
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 */
287 static int h263p_decode_umotion(MpegEncContext * s, int pred)
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  */
313 static void preview_obmc(MpegEncContext *s){
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 
327  av_assert2(s->pict_type == AV_PICTURE_TYPE_P);
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 
338  s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
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){
345  s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
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) {
357  s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
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 {
375  s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
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 
405 static void h263_decode_dquant(MpegEncContext *s){
406  static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
407 
408  if(s->modified_quant){
409  if(get_bits1(&s->gb))
410  s->qscale= ff_modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
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 level, i, j, 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);
464  if(s->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
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  {
483  OPEN_READER(re, &s->gb);
484  i--; // offset by -1 to allow direct indexing of scan_table
485  for(;;) {
486  UPDATE_CACHE(re, &s->gb);
487  GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
488  if (run == 66) {
489  if (level){
490  CLOSE_READER(re, &s->gb);
491  av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
492  return -1;
493  }
494  /* escape */
495  if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
496  int is11 = SHOW_UBITS(re, &s->gb, 1);
497  SKIP_CACHE(re, &s->gb, 1);
498  run = SHOW_UBITS(re, &s->gb, 7) + 1;
499  if (is11) {
500  SKIP_COUNTER(re, &s->gb, 1 + 7);
501  UPDATE_CACHE(re, &s->gb);
502  level = SHOW_SBITS(re, &s->gb, 11);
503  SKIP_COUNTER(re, &s->gb, 11);
504  } else {
505  SKIP_CACHE(re, &s->gb, 7);
506  level = SHOW_SBITS(re, &s->gb, 7);
507  SKIP_COUNTER(re, &s->gb, 1 + 7 + 7);
508  }
509  } else {
510  run = SHOW_UBITS(re, &s->gb, 7) + 1;
511  SKIP_CACHE(re, &s->gb, 7);
512  level = (int8_t)SHOW_UBITS(re, &s->gb, 8);
513  SKIP_COUNTER(re, &s->gb, 7 + 8);
514  if(level == -128){
515  UPDATE_CACHE(re, &s->gb);
516  if (s->codec_id == AV_CODEC_ID_RV10) {
517  /* XXX: should patch encoder too */
518  level = SHOW_SBITS(re, &s->gb, 12);
519  SKIP_COUNTER(re, &s->gb, 12);
520  }else{
521  level = SHOW_UBITS(re, &s->gb, 5);
522  SKIP_CACHE(re, &s->gb, 5);
523  level |= SHOW_SBITS(re, &s->gb, 6)<<5;
524  SKIP_COUNTER(re, &s->gb, 5 + 6);
525  }
526  }
527  }
528  } else {
529  if (SHOW_UBITS(re, &s->gb, 1))
530  level = -level;
531  SKIP_COUNTER(re, &s->gb, 1);
532  }
533  i += run;
534  if (i >= 64){
535  CLOSE_READER(re, &s->gb);
536  // redo update without last flag, revert -1 offset
537  i = i - run + ((run-1)&63) + 1;
538  if (i < 64) {
539  // only last marker, no overrun
540  block[scan_table[i]] = level;
541  break;
542  }
543  if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
544  //Looks like a hack but no, it's the way it is supposed to work ...
545  rl = &ff_rl_intra_aic;
546  i = 0;
547  s->gb= gb;
548  s->bdsp.clear_block(block);
549  goto retry;
550  }
551  av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
552  return -1;
553  }
554  j = scan_table[i];
555  block[j] = level;
556  }
557  }
558 not_coded:
559  if (s->mb_intra && s->h263_aic) {
560  ff_h263_pred_acdc(s, block, n);
561  i = 63;
562  }
563  s->block_last_index[n] = i;
564  return 0;
565 }
566 
567 static int h263_skip_b_part(MpegEncContext *s, int cbp)
568 {
569  LOCAL_ALIGNED_16(int16_t, dblock, [64]);
570  int i, mbi;
571  int bli[6];
572 
573  /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
574  * but real value should be restored in order to be used later (in OBMC condition)
575  */
576  mbi = s->mb_intra;
577  memcpy(bli, s->block_last_index, sizeof(bli));
578  s->mb_intra = 0;
579  for (i = 0; i < 6; i++) {
580  if (h263_decode_block(s, dblock, i, cbp&32) < 0)
581  return -1;
582  cbp+=cbp;
583  }
584  s->mb_intra = mbi;
585  memcpy(s->block_last_index, bli, sizeof(bli));
586  return 0;
587 }
588 
589 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
590 {
591  int c, mv = 1;
592 
593  if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
594  c = get_bits1(gb);
595  if (pb_frame == 2 && c)
596  mv = !get_bits1(gb);
597  } else { // h.263 Annex M improved PB-frame
598  mv = get_unary(gb, 0, 4) + 1;
599  c = mv & 1;
600  mv = !!(mv & 2);
601  }
602  if(c)
603  *cbpb = get_bits(gb, 6);
604  return mv;
605 }
606 
607 int ff_h263_decode_mb(MpegEncContext *s,
608  int16_t block[6][64])
609 {
610  int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
611  int16_t *mot_val;
612  const int xy= s->mb_x + s->mb_y * s->mb_stride;
613  int cbpb = 0, pb_mv_count = 0;
614 
615  av_assert2(!s->h263_pred);
616 
617  if (s->pict_type == AV_PICTURE_TYPE_P) {
618  do{
619  if (get_bits1(&s->gb)) {
620  /* skip mb */
621  s->mb_intra = 0;
622  for(i=0;i<6;i++)
623  s->block_last_index[i] = -1;
624  s->mv_dir = MV_DIR_FORWARD;
625  s->mv_type = MV_TYPE_16X16;
626  s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
627  s->mv[0][0][0] = 0;
628  s->mv[0][0][1] = 0;
629  s->mb_skipped = !(s->obmc | s->loop_filter);
630  goto end;
631  }
632  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
633  if (cbpc < 0){
634  av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
635  return -1;
636  }
637  }while(cbpc == 20);
638 
639  s->bdsp.clear_blocks(s->block[0]);
640 
641  dquant = cbpc & 8;
642  s->mb_intra = ((cbpc & 4) != 0);
643  if (s->mb_intra) goto intra;
644 
645  if(s->pb_frame && get_bits1(&s->gb))
646  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
647  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
648 
649  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
650  cbpy ^= 0xF;
651 
652  cbp = (cbpc & 3) | (cbpy << 2);
653  if (dquant) {
654  h263_decode_dquant(s);
655  }
656 
657  s->mv_dir = MV_DIR_FORWARD;
658  if ((cbpc & 16) == 0) {
659  s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
660  /* 16x16 motion prediction */
661  s->mv_type = MV_TYPE_16X16;
662  ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
663  if (s->umvplus)
664  mx = h263p_decode_umotion(s, pred_x);
665  else
666  mx = ff_h263_decode_motion(s, pred_x, 1);
667 
668  if (mx >= 0xffff)
669  return -1;
670 
671  if (s->umvplus)
672  my = h263p_decode_umotion(s, pred_y);
673  else
674  my = ff_h263_decode_motion(s, pred_y, 1);
675 
676  if (my >= 0xffff)
677  return -1;
678  s->mv[0][0][0] = mx;
679  s->mv[0][0][1] = my;
680 
681  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
682  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
683  } else {
684  s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
685  s->mv_type = MV_TYPE_8X8;
686  for(i=0;i<4;i++) {
687  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
688  if (s->umvplus)
689  mx = h263p_decode_umotion(s, pred_x);
690  else
691  mx = ff_h263_decode_motion(s, pred_x, 1);
692  if (mx >= 0xffff)
693  return -1;
694 
695  if (s->umvplus)
696  my = h263p_decode_umotion(s, pred_y);
697  else
698  my = ff_h263_decode_motion(s, pred_y, 1);
699  if (my >= 0xffff)
700  return -1;
701  s->mv[0][i][0] = mx;
702  s->mv[0][i][1] = my;
703  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
704  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
705  mot_val[0] = mx;
706  mot_val[1] = my;
707  }
708  }
709  } else if(s->pict_type==AV_PICTURE_TYPE_B) {
710  int mb_type;
711  const int stride= s->b8_stride;
712  int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
713  int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
714 // const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
715 
716  //FIXME ugly
717  mot_val0[0 ]= mot_val0[2 ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
718  mot_val0[1 ]= mot_val0[3 ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
719  mot_val1[0 ]= mot_val1[2 ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
720  mot_val1[1 ]= mot_val1[3 ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
721 
722  do{
723  mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
724  if (mb_type < 0){
725  av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
726  return -1;
727  }
728 
729  mb_type= h263_mb_type_b_map[ mb_type ];
730  }while(!mb_type);
731 
732  s->mb_intra = IS_INTRA(mb_type);
733  if(HAS_CBP(mb_type)){
734  s->bdsp.clear_blocks(s->block[0]);
735  cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
736  if(s->mb_intra){
737  dquant = IS_QUANT(mb_type);
738  goto intra;
739  }
740 
741  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
742 
743  if (cbpy < 0){
744  av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
745  return -1;
746  }
747 
748  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
749  cbpy ^= 0xF;
750 
751  cbp = (cbpc & 3) | (cbpy << 2);
752  }else
753  cbp=0;
754 
755  av_assert2(!s->mb_intra);
756 
757  if(IS_QUANT(mb_type)){
758  h263_decode_dquant(s);
759  }
760 
761  if(IS_DIRECT(mb_type)){
762  s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
763  mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
764  }else{
765  s->mv_dir = 0;
766  s->mv_type= MV_TYPE_16X16;
767 //FIXME UMV
768 
769  if(USES_LIST(mb_type, 0)){
770  int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
771  s->mv_dir = MV_DIR_FORWARD;
772 
773  mx = ff_h263_decode_motion(s, mx, 1);
774  my = ff_h263_decode_motion(s, my, 1);
775 
776  s->mv[0][0][0] = mx;
777  s->mv[0][0][1] = my;
778  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
779  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
780  }
781 
782  if(USES_LIST(mb_type, 1)){
783  int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
784  s->mv_dir |= MV_DIR_BACKWARD;
785 
786  mx = ff_h263_decode_motion(s, mx, 1);
787  my = ff_h263_decode_motion(s, my, 1);
788 
789  s->mv[1][0][0] = mx;
790  s->mv[1][0][1] = my;
791  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
792  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
793  }
794  }
795 
796  s->current_picture.mb_type[xy] = mb_type;
797  } else { /* I-Frame */
798  do{
799  cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
800  if (cbpc < 0){
801  av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
802  return -1;
803  }
804  }while(cbpc == 8);
805 
806  s->bdsp.clear_blocks(s->block[0]);
807 
808  dquant = cbpc & 4;
809  s->mb_intra = 1;
810 intra:
811  s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
812  if (s->h263_aic) {
813  s->ac_pred = get_bits1(&s->gb);
814  if(s->ac_pred){
815  s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
816 
817  s->h263_aic_dir = get_bits1(&s->gb);
818  }
819  }else
820  s->ac_pred = 0;
821 
822  if(s->pb_frame && get_bits1(&s->gb))
823  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
824  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
825  if(cbpy<0){
826  av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
827  return -1;
828  }
829  cbp = (cbpc & 3) | (cbpy << 2);
830  if (dquant) {
831  h263_decode_dquant(s);
832  }
833 
834  pb_mv_count += !!s->pb_frame;
835  }
836 
837  while(pb_mv_count--){
838  ff_h263_decode_motion(s, 0, 1);
839  ff_h263_decode_motion(s, 0, 1);
840  }
841 
842  /* decode each block */
843  for (i = 0; i < 6; i++) {
844  if (h263_decode_block(s, block[i], i, cbp&32) < 0)
845  return -1;
846  cbp+=cbp;
847  }
848 
849  if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
850  return -1;
851  if(s->obmc && !s->mb_intra){
852  if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
853  preview_obmc(s);
854  }
855 end:
856 
857  /* per-MB end of slice check */
858  {
859  int v= show_bits(&s->gb, 16);
860 
861  if (get_bits_left(&s->gb) < 16) {
862  v >>= 16 - get_bits_left(&s->gb);
863  }
864 
865  if(v==0)
866  return SLICE_END;
867  }
868 
869  return SLICE_OK;
870 }
871 
872 /* most is hardcoded. should extend to handle all h263 streams */
873 int ff_h263_decode_picture_header(MpegEncContext *s)
874 {
875  int format, width, height, i;
876  uint32_t startcode;
877 
878  align_get_bits(&s->gb);
879 
880  if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
881  av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
882  }
883 
884  startcode= get_bits(&s->gb, 22-8);
885 
886  for(i= get_bits_left(&s->gb); i>24; i-=8) {
887  startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
888 
889  if(startcode == 0x20)
890  break;
891  }
892 
893  if (startcode != 0x20) {
894  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
895  return -1;
896  }
897  /* temporal reference */
898  i = get_bits(&s->gb, 8); /* picture timestamp */
899  if( (s->picture_number&~0xFF)+i < s->picture_number)
900  i+= 256;
901  s->picture_number= (s->picture_number&~0xFF) + i;
902 
903  /* PTYPE starts here */
904  if (get_bits1(&s->gb) != 1) {
905  /* marker */
906  av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
907  return -1;
908  }
909  if (get_bits1(&s->gb) != 0) {
910  av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
911  return -1; /* h263 id */
912  }
913  skip_bits1(&s->gb); /* split screen off */
914  skip_bits1(&s->gb); /* camera off */
915  skip_bits1(&s->gb); /* freeze picture release off */
916 
917  format = get_bits(&s->gb, 3);
918  /*
919  0 forbidden
920  1 sub-QCIF
921  10 QCIF
922  7 extended PTYPE (PLUSPTYPE)
923  */
924 
925  if (format != 7 && format != 6) {
926  s->h263_plus = 0;
927  /* H.263v1 */
928  width = ff_h263_format[format][0];
929  height = ff_h263_format[format][1];
930  if (!width)
931  return -1;
932 
933  s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
934 
935  s->h263_long_vectors = get_bits1(&s->gb);
936 
937  if (get_bits1(&s->gb) != 0) {
938  av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
939  return -1; /* SAC: off */
940  }
941  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
942  s->unrestricted_mv = s->h263_long_vectors || s->obmc;
943 
944  s->pb_frame = get_bits1(&s->gb);
945  s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
946  skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
947 
948  s->width = width;
949  s->height = height;
950  s->avctx->sample_aspect_ratio= (AVRational){12,11};
951  s->avctx->framerate = (AVRational){ 30000, 1001 };
952  } else {
953  int ufep;
954 
955  /* H.263v2 */
956  s->h263_plus = 1;
957  ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
958 
959  /* ufep other than 0 and 1 are reserved */
960  if (ufep == 1) {
961  /* OPPTYPE */
962  format = get_bits(&s->gb, 3);
963  av_dlog(s->avctx, "ufep=1, format: %d\n", format);
964  s->custom_pcf= get_bits1(&s->gb);
965  s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
966  if (get_bits1(&s->gb) != 0) {
967  av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
968  }
969  s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
970  s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
971  s->loop_filter= get_bits1(&s->gb);
972  s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
973  if(s->avctx->lowres)
974  s->loop_filter = 0;
975 
976  s->h263_slice_structured= get_bits1(&s->gb);
977  if (get_bits1(&s->gb) != 0) {
978  av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
979  }
980  if (get_bits1(&s->gb) != 0) {
981  av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
982  }
983  s->alt_inter_vlc= get_bits1(&s->gb);
984  s->modified_quant= get_bits1(&s->gb);
985  if(s->modified_quant)
986  s->chroma_qscale_table= ff_h263_chroma_qscale_table;
987 
988  skip_bits(&s->gb, 1); /* Prevent start code emulation */
989 
990  skip_bits(&s->gb, 3); /* Reserved */
991  } else if (ufep != 0) {
992  av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
993  return -1;
994  }
995 
996  /* MPPTYPE */
997  s->pict_type = get_bits(&s->gb, 3);
998  switch(s->pict_type){
999  case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
1000  case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
1001  case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
1002  case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
1003  case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
1004  default:
1005  return -1;
1006  }
1007  skip_bits(&s->gb, 2);
1008  s->no_rounding = get_bits1(&s->gb);
1009  skip_bits(&s->gb, 4);
1010 
1011  /* Get the picture dimensions */
1012  if (ufep) {
1013  if (format == 6) {
1014  /* Custom Picture Format (CPFMT) */
1015  s->aspect_ratio_info = get_bits(&s->gb, 4);
1016  av_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1017  /* aspect ratios:
1018  0 - forbidden
1019  1 - 1:1
1020  2 - 12:11 (CIF 4:3)
1021  3 - 10:11 (525-type 4:3)
1022  4 - 16:11 (CIF 16:9)
1023  5 - 40:33 (525-type 16:9)
1024  6-14 - reserved
1025  */
1026  width = (get_bits(&s->gb, 9) + 1) * 4;
1027  skip_bits1(&s->gb);
1028  height = get_bits(&s->gb, 9) * 4;
1029  av_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1030  if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1031  /* aspected dimensions */
1032  s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1033  s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1034  }else{
1035  s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
1036  }
1037  } else {
1038  width = ff_h263_format[format][0];
1039  height = ff_h263_format[format][1];
1040  s->avctx->sample_aspect_ratio= (AVRational){12,11};
1041  }
1042  s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
1043  if ((width == 0) || (height == 0))
1044  return -1;
1045  s->width = width;
1046  s->height = height;
1047 
1048  if(s->custom_pcf){
1049  int gcd;
1050  s->avctx->framerate.num = 1800000;
1051  s->avctx->framerate.den = 1000 + get_bits1(&s->gb);
1052  s->avctx->framerate.den *= get_bits(&s->gb, 7);
1053  if(s->avctx->framerate.den == 0){
1054  av_log(s, AV_LOG_ERROR, "zero framerate\n");
1055  return -1;
1056  }
1057  gcd= av_gcd(s->avctx->framerate.den, s->avctx->framerate.num);
1058  s->avctx->framerate.den /= gcd;
1059  s->avctx->framerate.num /= gcd;
1060  }else{
1061  s->avctx->framerate = (AVRational){ 30000, 1001 };
1062  }
1063  }
1064 
1065  if(s->custom_pcf){
1066  skip_bits(&s->gb, 2); //extended Temporal reference
1067  }
1068 
1069  if (ufep) {
1070  if (s->umvplus) {
1071  if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1072  skip_bits1(&s->gb);
1073  }
1074  if(s->h263_slice_structured){
1075  if (get_bits1(&s->gb) != 0) {
1076  av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1077  }
1078  if (get_bits1(&s->gb) != 0) {
1079  av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1080  }
1081  }
1082  }
1083 
1084  s->qscale = get_bits(&s->gb, 5);
1085  }
1086 
1087  if (s->width == 0 || s->height == 0) {
1088  av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1089  return -1;
1090  }
1091  s->mb_width = (s->width + 15) / 16;
1092  s->mb_height = (s->height + 15) / 16;
1093  s->mb_num = s->mb_width * s->mb_height;
1094 
1095  if (s->pb_frame) {
1096  skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1097  if (s->custom_pcf)
1098  skip_bits(&s->gb, 2); //extended Temporal reference
1099  skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1100  }
1101 
1102  if (s->pict_type!=AV_PICTURE_TYPE_B) {
1103  s->time = s->picture_number;
1104  s->pp_time = s->time - s->last_non_b_time;
1105  s->last_non_b_time = s->time;
1106  }else{
1107  s->time = s->picture_number;
1108  s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1109  if (s->pp_time <=s->pb_time ||
1110  s->pp_time <= s->pp_time - s->pb_time ||
1111  s->pp_time <= 0){
1112  s->pp_time = 2;
1113  s->pb_time = 1;
1114  }
1115  ff_mpeg4_init_direct_mv(s);
1116  }
1117 
1118  /* PEI */
1119  if (skip_1stop_8data_bits(&s->gb) < 0)
1120  return AVERROR_INVALIDDATA;
1121 
1122  if(s->h263_slice_structured){
1123  if (get_bits1(&s->gb) != 1) {
1124  av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1125  return -1;
1126  }
1127 
1128  ff_h263_decode_mba(s);
1129 
1130  if (get_bits1(&s->gb) != 1) {
1131  av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1132  return -1;
1133  }
1134  }
1135  s->f_code = 1;
1136 
1137  if(s->h263_aic){
1138  s->y_dc_scale_table=
1139  s->c_dc_scale_table= ff_aic_dc_scale_table;
1140  }else{
1141  s->y_dc_scale_table=
1142  s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
1143  }
1144 
1145  ff_h263_show_pict_info(s);
1146  if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1147  int i,j;
1148  for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1149  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1150  for(i=0; i<13; i++){
1151  for(j=0; j<3; j++){
1152  int v= get_bits(&s->gb, 8);
1153  v |= get_sbits(&s->gb, 8)<<8;
1154  av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1155  }
1156  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1157  }
1158  for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1159  }
1160 
1161  return 0;
1162 }
Generated on Fri Dec 5 2014 04:41:56 for FFmpeg by   doxygen 1.8.2