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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 (CONFIG_RV10_DECODER && s->codec_id == AV_CODEC_ID_RV10) {
439  if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
440  int component, diff;
441  component = (n <= 3 ? 0 : n - 4 + 1);
442  level = s->last_dc[component];
443  if (s->rv10_first_dc_coded[component]) {
444  diff = ff_rv_decode_dc(s, n);
445  if (diff == 0xffff)
446  return -1;
447  level += diff;
448  level = level & 0xff; /* handle wrap round */
449  s->last_dc[component] = level;
450  } else {
451  s->rv10_first_dc_coded[component] = 1;
452  }
453  } else {
454  level = get_bits(&s->gb, 8);
455  if (level == 255)
456  level = 128;
457  }
458  }else{
459  level = get_bits(&s->gb, 8);
460  if((level&0x7F) == 0){
461  av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
462  if(s->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
463  return -1;
464  }
465  if (level == 255)
466  level = 128;
467  }
468  block[0] = level;
469  i = 1;
470  } else {
471  i = 0;
472  }
473  if (!coded) {
474  if (s->mb_intra && s->h263_aic)
475  goto not_coded;
476  s->block_last_index[n] = i - 1;
477  return 0;
478  }
479 retry:
480  {
481  OPEN_READER(re, &s->gb);
482  i--; // offset by -1 to allow direct indexing of scan_table
483  for(;;) {
484  UPDATE_CACHE(re, &s->gb);
485  GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
486  if (run == 66) {
487  if (level){
488  CLOSE_READER(re, &s->gb);
489  av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
490  return -1;
491  }
492  /* escape */
493  if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
494  int is11 = SHOW_UBITS(re, &s->gb, 1);
495  SKIP_CACHE(re, &s->gb, 1);
496  run = SHOW_UBITS(re, &s->gb, 7) + 1;
497  if (is11) {
498  SKIP_COUNTER(re, &s->gb, 1 + 7);
499  UPDATE_CACHE(re, &s->gb);
500  level = SHOW_SBITS(re, &s->gb, 11);
501  SKIP_COUNTER(re, &s->gb, 11);
502  } else {
503  SKIP_CACHE(re, &s->gb, 7);
504  level = SHOW_SBITS(re, &s->gb, 7);
505  SKIP_COUNTER(re, &s->gb, 1 + 7 + 7);
506  }
507  } else {
508  run = SHOW_UBITS(re, &s->gb, 7) + 1;
509  SKIP_CACHE(re, &s->gb, 7);
510  level = (int8_t)SHOW_UBITS(re, &s->gb, 8);
511  SKIP_COUNTER(re, &s->gb, 7 + 8);
512  if(level == -128){
513  UPDATE_CACHE(re, &s->gb);
514  if (s->codec_id == AV_CODEC_ID_RV10) {
515  /* XXX: should patch encoder too */
516  level = SHOW_SBITS(re, &s->gb, 12);
517  SKIP_COUNTER(re, &s->gb, 12);
518  }else{
519  level = SHOW_UBITS(re, &s->gb, 5);
520  SKIP_CACHE(re, &s->gb, 5);
521  level |= SHOW_SBITS(re, &s->gb, 6)<<5;
522  SKIP_COUNTER(re, &s->gb, 5 + 6);
523  }
524  }
525  }
526  } else {
527  if (SHOW_UBITS(re, &s->gb, 1))
528  level = -level;
529  SKIP_COUNTER(re, &s->gb, 1);
530  }
531  i += run;
532  if (i >= 64){
533  CLOSE_READER(re, &s->gb);
534  // redo update without last flag, revert -1 offset
535  i = i - run + ((run-1)&63) + 1;
536  if (i < 64) {
537  // only last marker, no overrun
538  block[scan_table[i]] = level;
539  break;
540  }
541  if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
542  //Looks like a hack but no, it's the way it is supposed to work ...
543  rl = &ff_rl_intra_aic;
544  i = 0;
545  s->gb= gb;
546  s->bdsp.clear_block(block);
547  goto retry;
548  }
549  av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
550  return -1;
551  }
552  j = scan_table[i];
553  block[j] = level;
554  }
555  }
556 not_coded:
557  if (s->mb_intra && s->h263_aic) {
558  ff_h263_pred_acdc(s, block, n);
559  i = 63;
560  }
561  s->block_last_index[n] = i;
562  return 0;
563 }
564 
565 static int h263_skip_b_part(MpegEncContext *s, int cbp)
566 {
567  LOCAL_ALIGNED_16(int16_t, dblock, [64]);
568  int i, mbi;
569  int bli[6];
570 
571  /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
572  * but real value should be restored in order to be used later (in OBMC condition)
573  */
574  mbi = s->mb_intra;
575  memcpy(bli, s->block_last_index, sizeof(bli));
576  s->mb_intra = 0;
577  for (i = 0; i < 6; i++) {
578  if (h263_decode_block(s, dblock, i, cbp&32) < 0)
579  return -1;
580  cbp+=cbp;
581  }
582  s->mb_intra = mbi;
583  memcpy(s->block_last_index, bli, sizeof(bli));
584  return 0;
585 }
586 
587 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
588 {
589  int c, mv = 1;
590 
591  if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
592  c = get_bits1(gb);
593  if (pb_frame == 2 && c)
594  mv = !get_bits1(gb);
595  } else { // h.263 Annex M improved PB-frame
596  mv = get_unary(gb, 0, 4) + 1;
597  c = mv & 1;
598  mv = !!(mv & 2);
599  }
600  if(c)
601  *cbpb = get_bits(gb, 6);
602  return mv;
603 }
604 
605 int ff_h263_decode_mb(MpegEncContext *s,
606  int16_t block[6][64])
607 {
608  int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
609  int16_t *mot_val;
610  const int xy= s->mb_x + s->mb_y * s->mb_stride;
611  int cbpb = 0, pb_mv_count = 0;
612 
613  av_assert2(!s->h263_pred);
614 
615  if (s->pict_type == AV_PICTURE_TYPE_P) {
616  do{
617  if (get_bits1(&s->gb)) {
618  /* skip mb */
619  s->mb_intra = 0;
620  for(i=0;i<6;i++)
621  s->block_last_index[i] = -1;
622  s->mv_dir = MV_DIR_FORWARD;
623  s->mv_type = MV_TYPE_16X16;
624  s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
625  s->mv[0][0][0] = 0;
626  s->mv[0][0][1] = 0;
627  s->mb_skipped = !(s->obmc | s->loop_filter);
628  goto end;
629  }
630  cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
631  if (cbpc < 0){
632  av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
633  return -1;
634  }
635  }while(cbpc == 20);
636 
637  s->bdsp.clear_blocks(s->block[0]);
638 
639  dquant = cbpc & 8;
640  s->mb_intra = ((cbpc & 4) != 0);
641  if (s->mb_intra) goto intra;
642 
643  if(s->pb_frame && get_bits1(&s->gb))
644  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
645  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
646 
647  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
648  cbpy ^= 0xF;
649 
650  cbp = (cbpc & 3) | (cbpy << 2);
651  if (dquant) {
652  h263_decode_dquant(s);
653  }
654 
655  s->mv_dir = MV_DIR_FORWARD;
656  if ((cbpc & 16) == 0) {
657  s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
658  /* 16x16 motion prediction */
659  s->mv_type = MV_TYPE_16X16;
660  ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
661  if (s->umvplus)
662  mx = h263p_decode_umotion(s, pred_x);
663  else
664  mx = ff_h263_decode_motion(s, pred_x, 1);
665 
666  if (mx >= 0xffff)
667  return -1;
668 
669  if (s->umvplus)
670  my = h263p_decode_umotion(s, pred_y);
671  else
672  my = ff_h263_decode_motion(s, pred_y, 1);
673 
674  if (my >= 0xffff)
675  return -1;
676  s->mv[0][0][0] = mx;
677  s->mv[0][0][1] = my;
678 
679  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
680  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
681  } else {
682  s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
683  s->mv_type = MV_TYPE_8X8;
684  for(i=0;i<4;i++) {
685  mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
686  if (s->umvplus)
687  mx = h263p_decode_umotion(s, pred_x);
688  else
689  mx = ff_h263_decode_motion(s, pred_x, 1);
690  if (mx >= 0xffff)
691  return -1;
692 
693  if (s->umvplus)
694  my = h263p_decode_umotion(s, pred_y);
695  else
696  my = ff_h263_decode_motion(s, pred_y, 1);
697  if (my >= 0xffff)
698  return -1;
699  s->mv[0][i][0] = mx;
700  s->mv[0][i][1] = my;
701  if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
702  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
703  mot_val[0] = mx;
704  mot_val[1] = my;
705  }
706  }
707  } else if(s->pict_type==AV_PICTURE_TYPE_B) {
708  int mb_type;
709  const int stride= s->b8_stride;
710  int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
711  int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
712 // const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
713 
714  //FIXME ugly
715  mot_val0[0 ]= mot_val0[2 ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
716  mot_val0[1 ]= mot_val0[3 ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
717  mot_val1[0 ]= mot_val1[2 ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
718  mot_val1[1 ]= mot_val1[3 ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
719 
720  do{
721  mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
722  if (mb_type < 0){
723  av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
724  return -1;
725  }
726 
727  mb_type= h263_mb_type_b_map[ mb_type ];
728  }while(!mb_type);
729 
730  s->mb_intra = IS_INTRA(mb_type);
731  if(HAS_CBP(mb_type)){
732  s->bdsp.clear_blocks(s->block[0]);
733  cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
734  if(s->mb_intra){
735  dquant = IS_QUANT(mb_type);
736  goto intra;
737  }
738 
739  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
740 
741  if (cbpy < 0){
742  av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
743  return -1;
744  }
745 
746  if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
747  cbpy ^= 0xF;
748 
749  cbp = (cbpc & 3) | (cbpy << 2);
750  }else
751  cbp=0;
752 
753  av_assert2(!s->mb_intra);
754 
755  if(IS_QUANT(mb_type)){
756  h263_decode_dquant(s);
757  }
758 
759  if(IS_DIRECT(mb_type)){
760  s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
761  mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
762  }else{
763  s->mv_dir = 0;
764  s->mv_type= MV_TYPE_16X16;
765 //FIXME UMV
766 
767  if(USES_LIST(mb_type, 0)){
768  int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
769  s->mv_dir = MV_DIR_FORWARD;
770 
771  mx = ff_h263_decode_motion(s, mx, 1);
772  my = ff_h263_decode_motion(s, my, 1);
773 
774  s->mv[0][0][0] = mx;
775  s->mv[0][0][1] = my;
776  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
777  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
778  }
779 
780  if(USES_LIST(mb_type, 1)){
781  int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
782  s->mv_dir |= MV_DIR_BACKWARD;
783 
784  mx = ff_h263_decode_motion(s, mx, 1);
785  my = ff_h263_decode_motion(s, my, 1);
786 
787  s->mv[1][0][0] = mx;
788  s->mv[1][0][1] = my;
789  mot_val[0 ]= mot_val[2 ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
790  mot_val[1 ]= mot_val[3 ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
791  }
792  }
793 
794  s->current_picture.mb_type[xy] = mb_type;
795  } else { /* I-Frame */
796  do{
797  cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
798  if (cbpc < 0){
799  av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
800  return -1;
801  }
802  }while(cbpc == 8);
803 
804  s->bdsp.clear_blocks(s->block[0]);
805 
806  dquant = cbpc & 4;
807  s->mb_intra = 1;
808 intra:
809  s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
810  if (s->h263_aic) {
811  s->ac_pred = get_bits1(&s->gb);
812  if(s->ac_pred){
813  s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
814 
815  s->h263_aic_dir = get_bits1(&s->gb);
816  }
817  }else
818  s->ac_pred = 0;
819 
820  if(s->pb_frame && get_bits1(&s->gb))
821  pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
822  cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
823  if(cbpy<0){
824  av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
825  return -1;
826  }
827  cbp = (cbpc & 3) | (cbpy << 2);
828  if (dquant) {
829  h263_decode_dquant(s);
830  }
831 
832  pb_mv_count += !!s->pb_frame;
833  }
834 
835  while(pb_mv_count--){
836  ff_h263_decode_motion(s, 0, 1);
837  ff_h263_decode_motion(s, 0, 1);
838  }
839 
840  /* decode each block */
841  for (i = 0; i < 6; i++) {
842  if (h263_decode_block(s, block[i], i, cbp&32) < 0)
843  return -1;
844  cbp+=cbp;
845  }
846 
847  if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
848  return -1;
849  if(s->obmc && !s->mb_intra){
850  if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
851  preview_obmc(s);
852  }
853 end:
854 
855  /* per-MB end of slice check */
856  {
857  int v= show_bits(&s->gb, 16);
858 
859  if (get_bits_left(&s->gb) < 16) {
860  v >>= 16 - get_bits_left(&s->gb);
861  }
862 
863  if(v==0)
864  return SLICE_END;
865  }
866 
867  return SLICE_OK;
868 }
869 
870 /* most is hardcoded. should extend to handle all h263 streams */
871 int ff_h263_decode_picture_header(MpegEncContext *s)
872 {
873  int format, width, height, i;
874  uint32_t startcode;
875 
876  align_get_bits(&s->gb);
877 
878  if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
879  av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
880  }
881 
882  startcode= get_bits(&s->gb, 22-8);
883 
884  for(i= get_bits_left(&s->gb); i>24; i-=8) {
885  startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
886 
887  if(startcode == 0x20)
888  break;
889  }
890 
891  if (startcode != 0x20) {
892  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
893  return -1;
894  }
895  /* temporal reference */
896  i = get_bits(&s->gb, 8); /* picture timestamp */
897  if( (s->picture_number&~0xFF)+i < s->picture_number)
898  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 
931  s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
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->framerate = (AVRational){ 30000, 1001 };
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 
974  s->h263_slice_structured= get_bits1(&s->gb);
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)
984  s->chroma_qscale_table= ff_h263_chroma_qscale_table;
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);
1028  if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
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{
1033  s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
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  }
1040  s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
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->framerate.num = 1800000;
1049  s->avctx->framerate.den = 1000 + get_bits1(&s->gb);
1050  s->avctx->framerate.den *= get_bits(&s->gb, 7);
1051  if(s->avctx->framerate.den == 0){
1052  av_log(s, AV_LOG_ERROR, "zero framerate\n");
1053  return -1;
1054  }
1055  gcd= av_gcd(s->avctx->framerate.den, s->avctx->framerate.num);
1056  s->avctx->framerate.den /= gcd;
1057  s->avctx->framerate.num /= gcd;
1058  }else{
1059  s->avctx->framerate = (AVRational){ 30000, 1001 };
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  }
1113  ff_mpeg4_init_direct_mv(s);
1114  }
1115 
1116  /* PEI */
1117  if (skip_1stop_8data_bits(&s->gb) < 0)
1118  return AVERROR_INVALIDDATA;
1119 
1120  if(s->h263_slice_structured){
1121  if (get_bits1(&s->gb) != 1) {
1122  av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1123  return -1;
1124  }
1125 
1126  ff_h263_decode_mba(s);
1127 
1128  if (get_bits1(&s->gb) != 1) {
1129  av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1130  return -1;
1131  }
1132  }
1133  s->f_code = 1;
1134 
1135  if(s->h263_aic){
1136  s->y_dc_scale_table=
1137  s->c_dc_scale_table= ff_aic_dc_scale_table;
1138  }else{
1139  s->y_dc_scale_table=
1140  s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
1141  }
1142 
1143  ff_h263_show_pict_info(s);
1144  if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1145  int i,j;
1146  for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1147  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1148  for(i=0; i<13; i++){
1149  for(j=0; j<3; j++){
1150  int v= get_bits(&s->gb, 8);
1151  v |= get_sbits(&s->gb, 8)<<8;
1152  av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1153  }
1154  av_log(s->avctx, AV_LOG_DEBUG, "\n");
1155  }
1156  for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1157  }
1158 
1159  return 0;
1160 }
Generated on Sun Mar 8 2015 02:34:54 for FFmpeg by   doxygen 1.8.2