bf9bd3488bcf0414e49a78c50413604b493bbb8c
[ffmpeg.git] / libavcodec / ituh263dec.c
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 }