Merge commit '9c1db92ad372d4cd69e0490e691c56e4097cb193'
[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 "internal.h"
40 #include "mathops.h"
41 #include "mpegutils.h"
42 #include "unary.h"
43 #include "flv.h"
44 #include "mpeg4video.h"
45
46 // The defines below define the number of bits that are read at once for
47 // reading vlc values. Changing these may improve speed and data cache needs
48 // be aware though that decreasing them may need the number of stages that is
49 // passed to get_vlc* to be increased.
50 #define MV_VLC_BITS 9
51 #define H263_MBTYPE_B_VLC_BITS 6
52 #define CBPC_B_VLC_BITS 3
53
54 static const int h263_mb_type_b_map[15]= {
55     MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
56     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
57     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
58                       MB_TYPE_L0                                 | MB_TYPE_16x16,
59                       MB_TYPE_L0   | MB_TYPE_CBP                 | MB_TYPE_16x16,
60                       MB_TYPE_L0   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
61                       MB_TYPE_L1                                 | MB_TYPE_16x16,
62                       MB_TYPE_L1   | MB_TYPE_CBP                 | MB_TYPE_16x16,
63                       MB_TYPE_L1   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
64                       MB_TYPE_L0L1                               | MB_TYPE_16x16,
65                       MB_TYPE_L0L1 | MB_TYPE_CBP                 | MB_TYPE_16x16,
66                       MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
67     0, //stuffing
68     MB_TYPE_INTRA4x4                | MB_TYPE_CBP,
69     MB_TYPE_INTRA4x4                | MB_TYPE_CBP | MB_TYPE_QUANT,
70 };
71
72 void ff_h263_show_pict_info(MpegEncContext *s){
73     if(s->avctx->debug&FF_DEBUG_PICT_INFO){
74     av_log(s->avctx, AV_LOG_DEBUG, "qp:%d %c size:%d rnd:%d%s%s%s%s%s%s%s%s%s %d/%d\n",
75          s->qscale, av_get_picture_type_char(s->pict_type),
76          s->gb.size_in_bits, 1-s->no_rounding,
77          s->obmc ? " AP" : "",
78          s->umvplus ? " UMV" : "",
79          s->h263_long_vectors ? " LONG" : "",
80          s->h263_plus ? " +" : "",
81          s->h263_aic ? " AIC" : "",
82          s->alt_inter_vlc ? " AIV" : "",
83          s->modified_quant ? " MQ" : "",
84          s->loop_filter ? " LOOP" : "",
85          s->h263_slice_structured ? " SS" : "",
86          s->avctx->framerate.num, s->avctx->framerate.den
87     );
88     }
89 }
90
91 /***********************************************/
92 /* decoding */
93
94 VLC ff_h263_intra_MCBPC_vlc;
95 VLC ff_h263_inter_MCBPC_vlc;
96 VLC ff_h263_cbpy_vlc;
97 static VLC mv_vlc;
98 static VLC h263_mbtype_b_vlc;
99 static VLC cbpc_b_vlc;
100
101 /* init vlcs */
102
103 /* XXX: find a better solution to handle static init */
104 av_cold void ff_h263_decode_init_vlc(void)
105 {
106     static volatile int done = 0;
107
108     if (!done) {
109         INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
110                  ff_h263_intra_MCBPC_bits, 1, 1,
111                  ff_h263_intra_MCBPC_code, 1, 1, 72);
112         INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
113                  ff_h263_inter_MCBPC_bits, 1, 1,
114                  ff_h263_inter_MCBPC_code, 1, 1, 198);
115         INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
116                  &ff_h263_cbpy_tab[0][1], 2, 1,
117                  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
118         INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
119                  &ff_mvtab[0][1], 2, 1,
120                  &ff_mvtab[0][0], 2, 1, 538);
121         ff_init_rl(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
122         ff_init_rl(&ff_rl_intra_aic, ff_h263_static_rl_table_store[1]);
123         INIT_VLC_RL(ff_h263_rl_inter, 554);
124         INIT_VLC_RL(ff_rl_intra_aic, 554);
125         INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
126                  &ff_h263_mbtype_b_tab[0][1], 2, 1,
127                  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
128         INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
129                  &ff_cbpc_b_tab[0][1], 2, 1,
130                  &ff_cbpc_b_tab[0][0], 2, 1, 8);
131         done = 1;
132     }
133 }
134
135 int ff_h263_decode_mba(MpegEncContext *s)
136 {
137     int i, mb_pos;
138
139     for(i=0; i<6; i++){
140         if(s->mb_num-1 <= ff_mba_max[i]) break;
141     }
142     mb_pos= get_bits(&s->gb, ff_mba_length[i]);
143     s->mb_x= mb_pos % s->mb_width;
144     s->mb_y= mb_pos / s->mb_width;
145
146     return mb_pos;
147 }
148
149 /**
150  * Decode the group of blocks header or slice header.
151  * @return <0 if an error occurred
152  */
153 static int h263_decode_gob_header(MpegEncContext *s)
154 {
155     unsigned int val, gob_number;
156     int left;
157
158     /* Check for GOB Start Code */
159     val = show_bits(&s->gb, 16);
160     if(val)
161         return -1;
162
163         /* We have a GBSC probably with GSTUFF */
164     skip_bits(&s->gb, 16); /* Drop the zeros */
165     left= get_bits_left(&s->gb);
166     //MN: we must check the bits left or we might end in a infinite loop (or segfault)
167     for(;left>13; left--){
168         if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
169     }
170     if(left<=13)
171         return -1;
172
173     if(s->h263_slice_structured){
174         if(check_marker(&s->gb, "before MBA")==0)
175             return -1;
176
177         ff_h263_decode_mba(s);
178
179         if(s->mb_num > 1583)
180             if(check_marker(&s->gb, "after MBA")==0)
181                 return -1;
182
183         s->qscale = get_bits(&s->gb, 5); /* SQUANT */
184         if(check_marker(&s->gb, "after SQUANT")==0)
185             return -1;
186         skip_bits(&s->gb, 2); /* GFID */
187     }else{
188         gob_number = get_bits(&s->gb, 5); /* GN */
189         s->mb_x= 0;
190         s->mb_y= s->gob_index* gob_number;
191         skip_bits(&s->gb, 2); /* GFID */
192         s->qscale = get_bits(&s->gb, 5); /* GQUANT */
193     }
194
195     if(s->mb_y >= s->mb_height)
196         return -1;
197
198     if(s->qscale==0)
199         return -1;
200
201     return 0;
202 }
203
204 /**
205  * Decode the group of blocks / video packet header.
206  * @return bit position of the resync_marker, or <0 if none was found
207  */
208 int ff_h263_resync(MpegEncContext *s){
209     int left, pos, ret;
210
211     if(s->codec_id==AV_CODEC_ID_MPEG4){
212         skip_bits1(&s->gb);
213         align_get_bits(&s->gb);
214     }
215
216     if(show_bits(&s->gb, 16)==0){
217         pos= get_bits_count(&s->gb);
218         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
219             ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
220         else
221             ret= h263_decode_gob_header(s);
222         if(ret>=0)
223             return pos;
224     }
225     //OK, it's not where it is supposed to be ...
226     s->gb= s->last_resync_gb;
227     align_get_bits(&s->gb);
228     left= get_bits_left(&s->gb);
229
230     for(;left>16+1+5+5; left-=8){
231         if(show_bits(&s->gb, 16)==0){
232             GetBitContext bak= s->gb;
233
234             pos= get_bits_count(&s->gb);
235             if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
236                 ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
237             else
238                 ret= h263_decode_gob_header(s);
239             if(ret>=0)
240                 return pos;
241
242             s->gb= bak;
243         }
244         skip_bits(&s->gb, 8);
245     }
246
247     return -1;
248 }
249
250 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
251 {
252     int code, val, sign, shift;
253     code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
254
255     if (code == 0)
256         return pred;
257     if (code < 0)
258         return 0xffff;
259
260     sign = get_bits1(&s->gb);
261     shift = f_code - 1;
262     val = code;
263     if (shift) {
264         val = (val - 1) << shift;
265         val |= get_bits(&s->gb, shift);
266         val++;
267     }
268     if (sign)
269         val = -val;
270     val += pred;
271
272     /* modulo decoding */
273     if (!s->h263_long_vectors) {
274         val = sign_extend(val, 5 + f_code);
275     } else {
276         /* horrible h263 long vector mode */
277         if (pred < -31 && val < -63)
278             val += 64;
279         if (pred > 32 && val > 63)
280             val -= 64;
281
282     }
283     return val;
284 }
285
286
287 /* Decode RVLC of H.263+ UMV */
288 static int h263p_decode_umotion(MpegEncContext * s, int pred)
289 {
290    int code = 0, sign;
291
292    if (get_bits1(&s->gb)) /* Motion difference = 0 */
293       return pred;
294
295    code = 2 + get_bits1(&s->gb);
296
297    while (get_bits1(&s->gb))
298    {
299       code <<= 1;
300       code += get_bits1(&s->gb);
301    }
302    sign = code & 1;
303    code >>= 1;
304
305    code = (sign) ? (pred - code) : (pred + code);
306    ff_tlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
307    return code;
308
309 }
310
311 /**
312  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
313  */
314 static void preview_obmc(MpegEncContext *s){
315     GetBitContext gb= s->gb;
316
317     int cbpc, i, pred_x, pred_y, mx, my;
318     int16_t *mot_val;
319     const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
320     const int stride= s->b8_stride*2;
321
322     for(i=0; i<4; i++)
323         s->block_index[i]+= 2;
324     for(i=4; i<6; i++)
325         s->block_index[i]+= 1;
326     s->mb_x++;
327
328     av_assert2(s->pict_type == AV_PICTURE_TYPE_P);
329
330     do{
331         if (get_bits1(&s->gb)) {
332             /* skip mb */
333             mot_val = s->current_picture.motion_val[0][s->block_index[0]];
334             mot_val[0       ]= mot_val[2       ]=
335             mot_val[0+stride]= mot_val[2+stride]= 0;
336             mot_val[1       ]= mot_val[3       ]=
337             mot_val[1+stride]= mot_val[3+stride]= 0;
338
339             s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
340             goto end;
341         }
342         cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
343     }while(cbpc == 20);
344
345     if(cbpc & 4){
346         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
347     }else{
348         get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
349         if (cbpc & 8) {
350             if(s->modified_quant){
351                 if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
352                 else                  skip_bits(&s->gb, 5);
353             }else
354                 skip_bits(&s->gb, 2);
355         }
356
357         if ((cbpc & 16) == 0) {
358                 s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
359                 /* 16x16 motion prediction */
360                 mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
361                 if (s->umvplus)
362                    mx = h263p_decode_umotion(s, pred_x);
363                 else
364                    mx = ff_h263_decode_motion(s, pred_x, 1);
365
366                 if (s->umvplus)
367                    my = h263p_decode_umotion(s, pred_y);
368                 else
369                    my = ff_h263_decode_motion(s, pred_y, 1);
370
371                 mot_val[0       ]= mot_val[2       ]=
372                 mot_val[0+stride]= mot_val[2+stride]= mx;
373                 mot_val[1       ]= mot_val[3       ]=
374                 mot_val[1+stride]= mot_val[3+stride]= my;
375         } else {
376             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
377             for(i=0;i<4;i++) {
378                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
379                 if (s->umvplus)
380                   mx = h263p_decode_umotion(s, pred_x);
381                 else
382                   mx = ff_h263_decode_motion(s, pred_x, 1);
383
384                 if (s->umvplus)
385                   my = h263p_decode_umotion(s, pred_y);
386                 else
387                   my = ff_h263_decode_motion(s, pred_y, 1);
388                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
389                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
390                 mot_val[0] = mx;
391                 mot_val[1] = my;
392             }
393         }
394     }
395 end:
396
397     for(i=0; i<4; i++)
398         s->block_index[i]-= 2;
399     for(i=4; i<6; i++)
400         s->block_index[i]-= 1;
401     s->mb_x--;
402
403     s->gb= gb;
404 }
405
406 static void h263_decode_dquant(MpegEncContext *s){
407     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
408
409     if(s->modified_quant){
410         if(get_bits1(&s->gb))
411             s->qscale= ff_modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
412         else
413             s->qscale= get_bits(&s->gb, 5);
414     }else
415         s->qscale += quant_tab[get_bits(&s->gb, 2)];
416     ff_set_qscale(s, s->qscale);
417 }
418
419 static int h263_decode_block(MpegEncContext * s, int16_t * block,
420                              int n, int coded)
421 {
422     int level, i, j, run;
423     RLTable *rl = &ff_h263_rl_inter;
424     const uint8_t *scan_table;
425     GetBitContext gb= s->gb;
426
427     scan_table = s->intra_scantable.permutated;
428     if (s->h263_aic && s->mb_intra) {
429         rl = &ff_rl_intra_aic;
430         i = 0;
431         if (s->ac_pred) {
432             if (s->h263_aic_dir)
433                 scan_table = s->intra_v_scantable.permutated; /* left */
434             else
435                 scan_table = s->intra_h_scantable.permutated; /* top */
436         }
437     } else if (s->mb_intra) {
438         /* DC coef */
439         if (CONFIG_RV10_DECODER && s->codec_id == AV_CODEC_ID_RV10) {
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         }else{
460             level = get_bits(&s->gb, 8);
461             if((level&0x7F) == 0){
462                 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
463                 if (s->avctx->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
464                     return -1;
465             }
466             if (level == 255)
467                 level = 128;
468         }
469         block[0] = level;
470         i = 1;
471     } else {
472         i = 0;
473     }
474     if (!coded) {
475         if (s->mb_intra && s->h263_aic)
476             goto not_coded;
477         s->block_last_index[n] = i - 1;
478         return 0;
479     }
480 retry:
481     {
482     OPEN_READER(re, &s->gb);
483     i--; // offset by -1 to allow direct indexing of scan_table
484     for(;;) {
485         UPDATE_CACHE(re, &s->gb);
486         GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
487         if (run == 66) {
488             if (level){
489                 CLOSE_READER(re, &s->gb);
490                 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
491                 return -1;
492             }
493             /* escape */
494             if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
495                 int is11 = SHOW_UBITS(re, &s->gb, 1);
496                 SKIP_CACHE(re, &s->gb, 1);
497                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
498                 if (is11) {
499                     SKIP_COUNTER(re, &s->gb, 1 + 7);
500                     UPDATE_CACHE(re, &s->gb);
501                     level = SHOW_SBITS(re, &s->gb, 11);
502                     SKIP_COUNTER(re, &s->gb, 11);
503                 } else {
504                     SKIP_CACHE(re, &s->gb, 7);
505                     level = SHOW_SBITS(re, &s->gb, 7);
506                     SKIP_COUNTER(re, &s->gb, 1 + 7 + 7);
507                 }
508             } else {
509                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
510                 SKIP_CACHE(re, &s->gb, 7);
511                 level = (int8_t)SHOW_UBITS(re, &s->gb, 8);
512                 SKIP_COUNTER(re, &s->gb, 7 + 8);
513                 if(level == -128){
514                     UPDATE_CACHE(re, &s->gb);
515                     if (s->codec_id == AV_CODEC_ID_RV10) {
516                         /* XXX: should patch encoder too */
517                         level = SHOW_SBITS(re, &s->gb, 12);
518                         SKIP_COUNTER(re, &s->gb, 12);
519                     }else{
520                         level = SHOW_UBITS(re, &s->gb, 5);
521                         SKIP_CACHE(re, &s->gb, 5);
522                         level |= SHOW_SBITS(re, &s->gb, 6)<<5;
523                         SKIP_COUNTER(re, &s->gb, 5 + 6);
524                     }
525                 }
526             }
527         } else {
528             if (SHOW_UBITS(re, &s->gb, 1))
529                 level = -level;
530             SKIP_COUNTER(re, &s->gb, 1);
531         }
532         i += run;
533         if (i >= 64){
534             CLOSE_READER(re, &s->gb);
535             // redo update without last flag, revert -1 offset
536             i = i - run + ((run-1)&63) + 1;
537             if (i < 64) {
538                 // only last marker, no overrun
539                 block[scan_table[i]] = level;
540                 break;
541             }
542             if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
543                 //Looks like a hack but no, it's the way it is supposed to work ...
544                 rl = &ff_rl_intra_aic;
545                 i = 0;
546                 s->gb= gb;
547                 s->bdsp.clear_block(block);
548                 goto retry;
549             }
550             av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
551             return -1;
552         }
553         j = scan_table[i];
554         block[j] = level;
555     }
556     }
557 not_coded:
558     if (s->mb_intra && s->h263_aic) {
559         ff_h263_pred_acdc(s, block, n);
560         i = 63;
561     }
562     s->block_last_index[n] = i;
563     return 0;
564 }
565
566 static int h263_skip_b_part(MpegEncContext *s, int cbp)
567 {
568     LOCAL_ALIGNED_16(int16_t, dblock, [64]);
569     int i, mbi;
570     int bli[6];
571
572     /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
573      * but real value should be restored in order to be used later (in OBMC condition)
574      */
575     mbi = s->mb_intra;
576     memcpy(bli, s->block_last_index, sizeof(bli));
577     s->mb_intra = 0;
578     for (i = 0; i < 6; i++) {
579         if (h263_decode_block(s, dblock, i, cbp&32) < 0)
580             return -1;
581         cbp+=cbp;
582     }
583     s->mb_intra = mbi;
584     memcpy(s->block_last_index, bli, sizeof(bli));
585     return 0;
586 }
587
588 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
589 {
590     int c, mv = 1;
591
592     if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
593         c = get_bits1(gb);
594         if (pb_frame == 2 && c)
595             mv = !get_bits1(gb);
596     } else { // h.263 Annex M improved PB-frame
597         mv = get_unary(gb, 0, 4) + 1;
598         c = mv & 1;
599         mv = !!(mv & 2);
600     }
601     if(c)
602         *cbpb = get_bits(gb, 6);
603     return mv;
604 }
605
606 int ff_h263_decode_mb(MpegEncContext *s,
607                       int16_t block[6][64])
608 {
609     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
610     int16_t *mot_val;
611     const int xy= s->mb_x + s->mb_y * s->mb_stride;
612     int cbpb = 0, pb_mv_count = 0;
613
614     av_assert2(!s->h263_pred);
615
616     if (s->pict_type == AV_PICTURE_TYPE_P) {
617         do{
618             if (get_bits1(&s->gb)) {
619                 /* skip mb */
620                 s->mb_intra = 0;
621                 for(i=0;i<6;i++)
622                     s->block_last_index[i] = -1;
623                 s->mv_dir = MV_DIR_FORWARD;
624                 s->mv_type = MV_TYPE_16X16;
625                 s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
626                 s->mv[0][0][0] = 0;
627                 s->mv[0][0][1] = 0;
628                 s->mb_skipped = !(s->obmc | s->loop_filter);
629                 goto end;
630             }
631             cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
632             if (cbpc < 0){
633                 av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
634                 return -1;
635             }
636         }while(cbpc == 20);
637
638         s->bdsp.clear_blocks(s->block[0]);
639
640         dquant = cbpc & 8;
641         s->mb_intra = ((cbpc & 4) != 0);
642         if (s->mb_intra) goto intra;
643
644         if(s->pb_frame && get_bits1(&s->gb))
645             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
646         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
647
648         if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
649             cbpy ^= 0xF;
650
651         cbp = (cbpc & 3) | (cbpy << 2);
652         if (dquant) {
653             h263_decode_dquant(s);
654         }
655
656         s->mv_dir = MV_DIR_FORWARD;
657         if ((cbpc & 16) == 0) {
658             s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
659             /* 16x16 motion prediction */
660             s->mv_type = MV_TYPE_16X16;
661             ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
662             if (s->umvplus)
663                mx = h263p_decode_umotion(s, pred_x);
664             else
665                mx = ff_h263_decode_motion(s, pred_x, 1);
666
667             if (mx >= 0xffff)
668                 return -1;
669
670             if (s->umvplus)
671                my = h263p_decode_umotion(s, pred_y);
672             else
673                my = ff_h263_decode_motion(s, pred_y, 1);
674
675             if (my >= 0xffff)
676                 return -1;
677             s->mv[0][0][0] = mx;
678             s->mv[0][0][1] = my;
679
680             if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
681                skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
682         } else {
683             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
684             s->mv_type = MV_TYPE_8X8;
685             for(i=0;i<4;i++) {
686                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
687                 if (s->umvplus)
688                   mx = h263p_decode_umotion(s, pred_x);
689                 else
690                   mx = ff_h263_decode_motion(s, pred_x, 1);
691                 if (mx >= 0xffff)
692                     return -1;
693
694                 if (s->umvplus)
695                   my = h263p_decode_umotion(s, pred_y);
696                 else
697                   my = ff_h263_decode_motion(s, pred_y, 1);
698                 if (my >= 0xffff)
699                     return -1;
700                 s->mv[0][i][0] = mx;
701                 s->mv[0][i][1] = my;
702                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
703                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
704                 mot_val[0] = mx;
705                 mot_val[1] = my;
706             }
707         }
708     } else if(s->pict_type==AV_PICTURE_TYPE_B) {
709         int mb_type;
710         const int stride= s->b8_stride;
711         int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
712         int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
713 //        const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
714
715         //FIXME ugly
716         mot_val0[0       ]= mot_val0[2       ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
717         mot_val0[1       ]= mot_val0[3       ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
718         mot_val1[0       ]= mot_val1[2       ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
719         mot_val1[1       ]= mot_val1[3       ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
720
721         do{
722             mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
723             if (mb_type < 0){
724                 av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
725                 return -1;
726             }
727
728             mb_type= h263_mb_type_b_map[ mb_type ];
729         }while(!mb_type);
730
731         s->mb_intra = IS_INTRA(mb_type);
732         if(HAS_CBP(mb_type)){
733             s->bdsp.clear_blocks(s->block[0]);
734             cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
735             if(s->mb_intra){
736                 dquant = IS_QUANT(mb_type);
737                 goto intra;
738             }
739
740             cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
741
742             if (cbpy < 0){
743                 av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
744                 return -1;
745             }
746
747             if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
748                 cbpy ^= 0xF;
749
750             cbp = (cbpc & 3) | (cbpy << 2);
751         }else
752             cbp=0;
753
754         av_assert2(!s->mb_intra);
755
756         if(IS_QUANT(mb_type)){
757             h263_decode_dquant(s);
758         }
759
760         if(IS_DIRECT(mb_type)){
761             s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
762             mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
763         }else{
764             s->mv_dir = 0;
765             s->mv_type= MV_TYPE_16X16;
766 //FIXME UMV
767
768             if(USES_LIST(mb_type, 0)){
769                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
770                 s->mv_dir = MV_DIR_FORWARD;
771
772                 mx = ff_h263_decode_motion(s, mx, 1);
773                 my = ff_h263_decode_motion(s, my, 1);
774
775                 s->mv[0][0][0] = mx;
776                 s->mv[0][0][1] = my;
777                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
778                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
779             }
780
781             if(USES_LIST(mb_type, 1)){
782                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
783                 s->mv_dir |= MV_DIR_BACKWARD;
784
785                 mx = ff_h263_decode_motion(s, mx, 1);
786                 my = ff_h263_decode_motion(s, my, 1);
787
788                 s->mv[1][0][0] = mx;
789                 s->mv[1][0][1] = my;
790                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
791                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
792             }
793         }
794
795         s->current_picture.mb_type[xy] = mb_type;
796     } else { /* I-Frame */
797         do{
798             cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
799             if (cbpc < 0){
800                 av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
801                 return -1;
802             }
803         }while(cbpc == 8);
804
805         s->bdsp.clear_blocks(s->block[0]);
806
807         dquant = cbpc & 4;
808         s->mb_intra = 1;
809 intra:
810         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
811         if (s->h263_aic) {
812             s->ac_pred = get_bits1(&s->gb);
813             if(s->ac_pred){
814                 s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
815
816                 s->h263_aic_dir = get_bits1(&s->gb);
817             }
818         }else
819             s->ac_pred = 0;
820
821         if(s->pb_frame && get_bits1(&s->gb))
822             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
823         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
824         if(cbpy<0){
825             av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
826             return -1;
827         }
828         cbp = (cbpc & 3) | (cbpy << 2);
829         if (dquant) {
830             h263_decode_dquant(s);
831         }
832
833         pb_mv_count += !!s->pb_frame;
834     }
835
836     while(pb_mv_count--){
837         ff_h263_decode_motion(s, 0, 1);
838         ff_h263_decode_motion(s, 0, 1);
839     }
840
841     /* decode each block */
842     for (i = 0; i < 6; i++) {
843         if (h263_decode_block(s, block[i], i, cbp&32) < 0)
844             return -1;
845         cbp+=cbp;
846     }
847
848     if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
849         return -1;
850     if(s->obmc && !s->mb_intra){
851         if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
852             preview_obmc(s);
853     }
854 end:
855
856         /* per-MB end of slice check */
857     {
858         int v= show_bits(&s->gb, 16);
859
860         if (get_bits_left(&s->gb) < 16) {
861             v >>= 16 - get_bits_left(&s->gb);
862         }
863
864         if(v==0)
865             return SLICE_END;
866     }
867
868     return SLICE_OK;
869 }
870
871 /* most is hardcoded. should extend to handle all h263 streams */
872 int ff_h263_decode_picture_header(MpegEncContext *s)
873 {
874     int format, width, height, i;
875     uint32_t startcode;
876
877     align_get_bits(&s->gb);
878
879     if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
880          av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
881     }
882
883     startcode= get_bits(&s->gb, 22-8);
884
885     for(i= get_bits_left(&s->gb); i>24; i-=8) {
886         startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
887
888         if(startcode == 0x20)
889             break;
890     }
891
892     if (startcode != 0x20) {
893         av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
894         return -1;
895     }
896     /* temporal reference */
897     i = get_bits(&s->gb, 8); /* picture timestamp */
898     if( (s->picture_number&~0xFF)+i < s->picture_number)
899         i+= 256;
900     s->picture_number= (s->picture_number&~0xFF) + i;
901
902     /* PTYPE starts here */
903     if (check_marker(&s->gb, "in PTYPE") != 1) {
904         return -1;
905     }
906     if (get_bits1(&s->gb) != 0) {
907         av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
908         return -1;      /* h263 id */
909     }
910     skip_bits1(&s->gb);         /* split screen off */
911     skip_bits1(&s->gb);         /* camera  off */
912     skip_bits1(&s->gb);         /* freeze picture release off */
913
914     format = get_bits(&s->gb, 3);
915     /*
916         0    forbidden
917         1    sub-QCIF
918         10   QCIF
919         7       extended PTYPE (PLUSPTYPE)
920     */
921
922     if (format != 7 && format != 6) {
923         s->h263_plus = 0;
924         /* H.263v1 */
925         width = ff_h263_format[format][0];
926         height = ff_h263_format[format][1];
927         if (!width)
928             return -1;
929
930         s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
931
932         s->h263_long_vectors = get_bits1(&s->gb);
933
934         if (get_bits1(&s->gb) != 0) {
935             av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
936             return -1; /* SAC: off */
937         }
938         s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
939         s->unrestricted_mv = s->h263_long_vectors || s->obmc;
940
941         s->pb_frame = get_bits1(&s->gb);
942         s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
943         skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
944
945         s->width = width;
946         s->height = height;
947         s->avctx->sample_aspect_ratio= (AVRational){12,11};
948         s->avctx->framerate = (AVRational){ 30000, 1001 };
949     } else {
950         int ufep;
951
952         /* H.263v2 */
953         s->h263_plus = 1;
954         ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
955
956         /* ufep other than 0 and 1 are reserved */
957         if (ufep == 1) {
958             /* OPPTYPE */
959             format = get_bits(&s->gb, 3);
960             ff_dlog(s->avctx, "ufep=1, format: %d\n", format);
961             s->custom_pcf= get_bits1(&s->gb);
962             s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
963             if (get_bits1(&s->gb) != 0) {
964                 av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
965             }
966             s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
967             s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
968             s->loop_filter= get_bits1(&s->gb);
969             s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
970             if(s->avctx->lowres)
971                 s->loop_filter = 0;
972
973             s->h263_slice_structured= get_bits1(&s->gb);
974             if (get_bits1(&s->gb) != 0) {
975                 av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
976             }
977             if (get_bits1(&s->gb) != 0) {
978                 av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
979             }
980             s->alt_inter_vlc= get_bits1(&s->gb);
981             s->modified_quant= get_bits1(&s->gb);
982             if(s->modified_quant)
983                 s->chroma_qscale_table= ff_h263_chroma_qscale_table;
984
985             skip_bits(&s->gb, 1); /* Prevent start code emulation */
986
987             skip_bits(&s->gb, 3); /* Reserved */
988         } else if (ufep != 0) {
989             av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
990             return -1;
991         }
992
993         /* MPPTYPE */
994         s->pict_type = get_bits(&s->gb, 3);
995         switch(s->pict_type){
996         case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
997         case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
998         case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
999         case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
1000         case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
1001         default:
1002             return -1;
1003         }
1004         skip_bits(&s->gb, 2);
1005         s->no_rounding = get_bits1(&s->gb);
1006         skip_bits(&s->gb, 4);
1007
1008         /* Get the picture dimensions */
1009         if (ufep) {
1010             if (format == 6) {
1011                 /* Custom Picture Format (CPFMT) */
1012                 s->aspect_ratio_info = get_bits(&s->gb, 4);
1013                 ff_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1014                 /* aspect ratios:
1015                 0 - forbidden
1016                 1 - 1:1
1017                 2 - 12:11 (CIF 4:3)
1018                 3 - 10:11 (525-type 4:3)
1019                 4 - 16:11 (CIF 16:9)
1020                 5 - 40:33 (525-type 16:9)
1021                 6-14 - reserved
1022                 */
1023                 width = (get_bits(&s->gb, 9) + 1) * 4;
1024                 check_marker(&s->gb, "in dimensions");
1025                 height = get_bits(&s->gb, 9) * 4;
1026                 ff_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1027                 if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1028                     /* aspected dimensions */
1029                     s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1030                     s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1031                 }else{
1032                     s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
1033                 }
1034             } else {
1035                 width = ff_h263_format[format][0];
1036                 height = ff_h263_format[format][1];
1037                 s->avctx->sample_aspect_ratio= (AVRational){12,11};
1038             }
1039             s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
1040             if ((width == 0) || (height == 0))
1041                 return -1;
1042             s->width = width;
1043             s->height = height;
1044
1045             if(s->custom_pcf){
1046                 int gcd;
1047                 s->avctx->framerate.num  = 1800000;
1048                 s->avctx->framerate.den  = 1000 + get_bits1(&s->gb);
1049                 s->avctx->framerate.den *= get_bits(&s->gb, 7);
1050                 if(s->avctx->framerate.den == 0){
1051                     av_log(s, AV_LOG_ERROR, "zero framerate\n");
1052                     return -1;
1053                 }
1054                 gcd= av_gcd(s->avctx->framerate.den, s->avctx->framerate.num);
1055                 s->avctx->framerate.den /= gcd;
1056                 s->avctx->framerate.num /= gcd;
1057             }else{
1058                 s->avctx->framerate = (AVRational){ 30000, 1001 };
1059             }
1060         }
1061
1062         if(s->custom_pcf){
1063             skip_bits(&s->gb, 2); //extended Temporal reference
1064         }
1065
1066         if (ufep) {
1067             if (s->umvplus) {
1068                 if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1069                     skip_bits1(&s->gb);
1070             }
1071             if(s->h263_slice_structured){
1072                 if (get_bits1(&s->gb) != 0) {
1073                     av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1074                 }
1075                 if (get_bits1(&s->gb) != 0) {
1076                     av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1077                 }
1078             }
1079         }
1080
1081         s->qscale = get_bits(&s->gb, 5);
1082     }
1083
1084     if (s->width == 0 || s->height == 0) {
1085         av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1086         return -1;
1087     }
1088     s->mb_width = (s->width  + 15) / 16;
1089     s->mb_height = (s->height  + 15) / 16;
1090     s->mb_num = s->mb_width * s->mb_height;
1091
1092     if (s->pb_frame) {
1093         skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1094         if (s->custom_pcf)
1095             skip_bits(&s->gb, 2); //extended Temporal reference
1096         skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1097     }
1098
1099     if (s->pict_type!=AV_PICTURE_TYPE_B) {
1100         s->time            = s->picture_number;
1101         s->pp_time         = s->time - s->last_non_b_time;
1102         s->last_non_b_time = s->time;
1103     }else{
1104         s->time    = s->picture_number;
1105         s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1106         if (s->pp_time <=s->pb_time ||
1107             s->pp_time <= s->pp_time - s->pb_time ||
1108             s->pp_time <= 0){
1109             s->pp_time = 2;
1110             s->pb_time = 1;
1111         }
1112         ff_mpeg4_init_direct_mv(s);
1113     }
1114
1115     /* PEI */
1116     if (skip_1stop_8data_bits(&s->gb) < 0)
1117         return AVERROR_INVALIDDATA;
1118
1119     if(s->h263_slice_structured){
1120         if (check_marker(&s->gb, "SEPB1") != 1) {
1121             return -1;
1122         }
1123
1124         ff_h263_decode_mba(s);
1125
1126         if (check_marker(&s->gb, "SEPB2") != 1) {
1127             return -1;
1128         }
1129     }
1130     s->f_code = 1;
1131
1132     if(s->h263_aic){
1133          s->y_dc_scale_table=
1134          s->c_dc_scale_table= ff_aic_dc_scale_table;
1135     }else{
1136         s->y_dc_scale_table=
1137         s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
1138     }
1139
1140         ff_h263_show_pict_info(s);
1141     if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1142         int i,j;
1143         for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1144         av_log(s->avctx, AV_LOG_DEBUG, "\n");
1145         for(i=0; i<13; i++){
1146             for(j=0; j<3; j++){
1147                 int v= get_bits(&s->gb, 8);
1148                 v |= get_sbits(&s->gb, 8)<<8;
1149                 av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1150             }
1151             av_log(s->avctx, AV_LOG_DEBUG, "\n");
1152         }
1153         for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1154     }
1155
1156     return 0;
1157 }