Merge commit 'e7af52a68dde9144b273a9598b60bf0f56e1323b'
[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 "h263data.h"
40 #include "internal.h"
41 #include "mathops.h"
42 #include "mpegutils.h"
43 #include "unary.h"
44 #include "flv.h"
45 #include "rv10.h"
46 #include "mpeg4video.h"
47 #include "mpegvideodata.h"
48
49 // The defines below define the number of bits that are read at once for
50 // reading vlc values. Changing these may improve speed and data cache needs
51 // be aware though that decreasing them may need the number of stages that is
52 // passed to get_vlc* to be increased.
53 #define MV_VLC_BITS 9
54 #define H263_MBTYPE_B_VLC_BITS 6
55 #define CBPC_B_VLC_BITS 3
56
57 static const int h263_mb_type_b_map[15]= {
58     MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
59     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
60     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
61                       MB_TYPE_L0                                 | MB_TYPE_16x16,
62                       MB_TYPE_L0   | MB_TYPE_CBP                 | MB_TYPE_16x16,
63                       MB_TYPE_L0   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
64                       MB_TYPE_L1                                 | MB_TYPE_16x16,
65                       MB_TYPE_L1   | MB_TYPE_CBP                 | MB_TYPE_16x16,
66                       MB_TYPE_L1   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
67                       MB_TYPE_L0L1                               | MB_TYPE_16x16,
68                       MB_TYPE_L0L1 | MB_TYPE_CBP                 | MB_TYPE_16x16,
69                       MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
70     0, //stuffing
71     MB_TYPE_INTRA4x4                | MB_TYPE_CBP,
72     MB_TYPE_INTRA4x4                | MB_TYPE_CBP | MB_TYPE_QUANT,
73 };
74
75 void ff_h263_show_pict_info(MpegEncContext *s){
76     if(s->avctx->debug&FF_DEBUG_PICT_INFO){
77     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",
78          s->qscale, av_get_picture_type_char(s->pict_type),
79          s->gb.size_in_bits, 1-s->no_rounding,
80          s->obmc ? " AP" : "",
81          s->umvplus ? " UMV" : "",
82          s->h263_long_vectors ? " LONG" : "",
83          s->h263_plus ? " +" : "",
84          s->h263_aic ? " AIC" : "",
85          s->alt_inter_vlc ? " AIV" : "",
86          s->modified_quant ? " MQ" : "",
87          s->loop_filter ? " LOOP" : "",
88          s->h263_slice_structured ? " SS" : "",
89          s->avctx->framerate.num, s->avctx->framerate.den
90     );
91     }
92 }
93
94 /***********************************************/
95 /* decoding */
96
97 VLC ff_h263_intra_MCBPC_vlc;
98 VLC ff_h263_inter_MCBPC_vlc;
99 VLC ff_h263_cbpy_vlc;
100 static VLC mv_vlc;
101 static VLC h263_mbtype_b_vlc;
102 static VLC cbpc_b_vlc;
103
104 /* init vlcs */
105
106 /* XXX: find a better solution to handle static init */
107 av_cold void ff_h263_decode_init_vlc(void)
108 {
109     static volatile int done = 0;
110
111     if (!done) {
112         INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
113                  ff_h263_intra_MCBPC_bits, 1, 1,
114                  ff_h263_intra_MCBPC_code, 1, 1, 72);
115         INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
116                  ff_h263_inter_MCBPC_bits, 1, 1,
117                  ff_h263_inter_MCBPC_code, 1, 1, 198);
118         INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
119                  &ff_h263_cbpy_tab[0][1], 2, 1,
120                  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
121         INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
122                  &ff_mvtab[0][1], 2, 1,
123                  &ff_mvtab[0][0], 2, 1, 538);
124         ff_rl_init(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
125         ff_rl_init(&ff_rl_intra_aic, ff_h263_static_rl_table_store[1]);
126         INIT_VLC_RL(ff_h263_rl_inter, 554);
127         INIT_VLC_RL(ff_rl_intra_aic, 554);
128         INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
129                  &ff_h263_mbtype_b_tab[0][1], 2, 1,
130                  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
131         INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
132                  &ff_cbpc_b_tab[0][1], 2, 1,
133                  &ff_cbpc_b_tab[0][0], 2, 1, 8);
134         done = 1;
135     }
136 }
137
138 int ff_h263_decode_mba(MpegEncContext *s)
139 {
140     int i, mb_pos;
141
142     for(i=0; i<6; i++){
143         if(s->mb_num-1 <= ff_mba_max[i]) break;
144     }
145     mb_pos= get_bits(&s->gb, ff_mba_length[i]);
146     s->mb_x= mb_pos % s->mb_width;
147     s->mb_y= mb_pos / s->mb_width;
148
149     return mb_pos;
150 }
151
152 /**
153  * Decode the group of blocks header or slice header.
154  * @return <0 if an error occurred
155  */
156 static int h263_decode_gob_header(MpegEncContext *s)
157 {
158     unsigned int val, gob_number;
159     int left;
160
161     /* Check for GOB Start Code */
162     val = show_bits(&s->gb, 16);
163     if(val)
164         return -1;
165
166         /* We have a GBSC probably with GSTUFF */
167     skip_bits(&s->gb, 16); /* Drop the zeros */
168     left= get_bits_left(&s->gb);
169     //MN: we must check the bits left or we might end in a infinite loop (or segfault)
170     for(;left>13; left--){
171         if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
172     }
173     if(left<=13)
174         return -1;
175
176     if(s->h263_slice_structured){
177         if(check_marker(&s->gb, "before MBA")==0)
178             return -1;
179
180         ff_h263_decode_mba(s);
181
182         if(s->mb_num > 1583)
183             if(check_marker(&s->gb, "after MBA")==0)
184                 return -1;
185
186         s->qscale = get_bits(&s->gb, 5); /* SQUANT */
187         if(check_marker(&s->gb, "after SQUANT")==0)
188             return -1;
189         skip_bits(&s->gb, 2); /* GFID */
190     }else{
191         gob_number = get_bits(&s->gb, 5); /* GN */
192         s->mb_x= 0;
193         s->mb_y= s->gob_index* gob_number;
194         skip_bits(&s->gb, 2); /* GFID */
195         s->qscale = get_bits(&s->gb, 5); /* GQUANT */
196     }
197
198     if(s->mb_y >= s->mb_height)
199         return -1;
200
201     if(s->qscale==0)
202         return -1;
203
204     return 0;
205 }
206
207 /**
208  * Decode the group of blocks / video packet header.
209  * @return bit position of the resync_marker, or <0 if none was found
210  */
211 int ff_h263_resync(MpegEncContext *s){
212     int left, pos, ret;
213
214     if(s->codec_id==AV_CODEC_ID_MPEG4){
215         skip_bits1(&s->gb);
216         align_get_bits(&s->gb);
217     }
218
219     if(show_bits(&s->gb, 16)==0){
220         pos= get_bits_count(&s->gb);
221         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
222             ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
223         else
224             ret= h263_decode_gob_header(s);
225         if(ret>=0)
226             return pos;
227     }
228     //OK, it's not where it is supposed to be ...
229     s->gb= s->last_resync_gb;
230     align_get_bits(&s->gb);
231     left= get_bits_left(&s->gb);
232
233     for(;left>16+1+5+5; left-=8){
234         if(show_bits(&s->gb, 16)==0){
235             GetBitContext bak= s->gb;
236
237             pos= get_bits_count(&s->gb);
238             if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
239                 ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
240             else
241                 ret= h263_decode_gob_header(s);
242             if(ret>=0)
243                 return pos;
244
245             s->gb= bak;
246         }
247         skip_bits(&s->gb, 8);
248     }
249
250     return -1;
251 }
252
253 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
254 {
255     int code, val, sign, shift;
256     code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
257
258     if (code == 0)
259         return pred;
260     if (code < 0)
261         return 0xffff;
262
263     sign = get_bits1(&s->gb);
264     shift = f_code - 1;
265     val = code;
266     if (shift) {
267         val = (val - 1) << shift;
268         val |= get_bits(&s->gb, shift);
269         val++;
270     }
271     if (sign)
272         val = -val;
273     val += pred;
274
275     /* modulo decoding */
276     if (!s->h263_long_vectors) {
277         val = sign_extend(val, 5 + f_code);
278     } else {
279         /* horrible h263 long vector mode */
280         if (pred < -31 && val < -63)
281             val += 64;
282         if (pred > 32 && val > 63)
283             val -= 64;
284
285     }
286     return val;
287 }
288
289
290 /* Decode RVLC of H.263+ UMV */
291 static int h263p_decode_umotion(MpegEncContext * s, int pred)
292 {
293    int code = 0, sign;
294
295    if (get_bits1(&s->gb)) /* Motion difference = 0 */
296       return pred;
297
298    code = 2 + get_bits1(&s->gb);
299
300    while (get_bits1(&s->gb))
301    {
302       code <<= 1;
303       code += get_bits1(&s->gb);
304    }
305    sign = code & 1;
306    code >>= 1;
307
308    code = (sign) ? (pred - code) : (pred + code);
309    ff_tlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
310    return code;
311
312 }
313
314 /**
315  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
316  */
317 static void preview_obmc(MpegEncContext *s){
318     GetBitContext gb= s->gb;
319
320     int cbpc, i, pred_x, pred_y, mx, my;
321     int16_t *mot_val;
322     const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
323     const int stride= s->b8_stride*2;
324
325     for(i=0; i<4; i++)
326         s->block_index[i]+= 2;
327     for(i=4; i<6; i++)
328         s->block_index[i]+= 1;
329     s->mb_x++;
330
331     av_assert2(s->pict_type == AV_PICTURE_TYPE_P);
332
333     do{
334         if (get_bits1(&s->gb)) {
335             /* skip mb */
336             mot_val = s->current_picture.motion_val[0][s->block_index[0]];
337             mot_val[0       ]= mot_val[2       ]=
338             mot_val[0+stride]= mot_val[2+stride]= 0;
339             mot_val[1       ]= mot_val[3       ]=
340             mot_val[1+stride]= mot_val[3+stride]= 0;
341
342             s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
343             goto end;
344         }
345         cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
346     }while(cbpc == 20);
347
348     if(cbpc & 4){
349         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
350     }else{
351         get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
352         if (cbpc & 8) {
353             if(s->modified_quant){
354                 if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
355                 else                  skip_bits(&s->gb, 5);
356             }else
357                 skip_bits(&s->gb, 2);
358         }
359
360         if ((cbpc & 16) == 0) {
361                 s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
362                 /* 16x16 motion prediction */
363                 mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
364                 if (s->umvplus)
365                    mx = h263p_decode_umotion(s, pred_x);
366                 else
367                    mx = ff_h263_decode_motion(s, pred_x, 1);
368
369                 if (s->umvplus)
370                    my = h263p_decode_umotion(s, pred_y);
371                 else
372                    my = ff_h263_decode_motion(s, pred_y, 1);
373
374                 mot_val[0       ]= mot_val[2       ]=
375                 mot_val[0+stride]= mot_val[2+stride]= mx;
376                 mot_val[1       ]= mot_val[3       ]=
377                 mot_val[1+stride]= mot_val[3+stride]= my;
378         } else {
379             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
380             for(i=0;i<4;i++) {
381                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
382                 if (s->umvplus)
383                   mx = h263p_decode_umotion(s, pred_x);
384                 else
385                   mx = ff_h263_decode_motion(s, pred_x, 1);
386
387                 if (s->umvplus)
388                   my = h263p_decode_umotion(s, pred_y);
389                 else
390                   my = ff_h263_decode_motion(s, pred_y, 1);
391                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
392                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
393                 mot_val[0] = mx;
394                 mot_val[1] = my;
395             }
396         }
397     }
398 end:
399
400     for(i=0; i<4; i++)
401         s->block_index[i]-= 2;
402     for(i=4; i<6; i++)
403         s->block_index[i]-= 1;
404     s->mb_x--;
405
406     s->gb= gb;
407 }
408
409 static void h263_decode_dquant(MpegEncContext *s){
410     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
411
412     if(s->modified_quant){
413         if(get_bits1(&s->gb))
414             s->qscale= ff_modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
415         else
416             s->qscale= get_bits(&s->gb, 5);
417     }else
418         s->qscale += quant_tab[get_bits(&s->gb, 2)];
419     ff_set_qscale(s, s->qscale);
420 }
421
422 static int h263_decode_block(MpegEncContext * s, int16_t * block,
423                              int n, int coded)
424 {
425     int level, i, j, run;
426     RLTable *rl = &ff_h263_rl_inter;
427     const uint8_t *scan_table;
428     GetBitContext gb= s->gb;
429
430     scan_table = s->intra_scantable.permutated;
431     if (s->h263_aic && s->mb_intra) {
432         rl = &ff_rl_intra_aic;
433         i = 0;
434         if (s->ac_pred) {
435             if (s->h263_aic_dir)
436                 scan_table = s->intra_v_scantable.permutated; /* left */
437             else
438                 scan_table = s->intra_h_scantable.permutated; /* top */
439         }
440     } else if (s->mb_intra) {
441         /* DC coef */
442         if (CONFIG_RV10_DECODER && s->codec_id == AV_CODEC_ID_RV10) {
443           if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
444             int component, diff;
445             component = (n <= 3 ? 0 : n - 4 + 1);
446             level = s->last_dc[component];
447             if (s->rv10_first_dc_coded[component]) {
448                 diff = ff_rv_decode_dc(s, n);
449                 if (diff == 0xffff)
450                     return -1;
451                 level += diff;
452                 level = level & 0xff; /* handle wrap round */
453                 s->last_dc[component] = level;
454             } else {
455                 s->rv10_first_dc_coded[component] = 1;
456             }
457           } else {
458                 level = get_bits(&s->gb, 8);
459                 if (level == 255)
460                     level = 128;
461           }
462         }else{
463             level = get_bits(&s->gb, 8);
464             if((level&0x7F) == 0){
465                 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
466                 if (s->avctx->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
467                     return -1;
468             }
469             if (level == 255)
470                 level = 128;
471         }
472         block[0] = level;
473         i = 1;
474     } else {
475         i = 0;
476     }
477     if (!coded) {
478         if (s->mb_intra && s->h263_aic)
479             goto not_coded;
480         s->block_last_index[n] = i - 1;
481         return 0;
482     }
483 retry:
484     {
485     OPEN_READER(re, &s->gb);
486     i--; // offset by -1 to allow direct indexing of scan_table
487     for(;;) {
488         UPDATE_CACHE(re, &s->gb);
489         GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
490         if (run == 66) {
491             if (level){
492                 CLOSE_READER(re, &s->gb);
493                 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
494                 return -1;
495             }
496             /* escape */
497             if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
498                 int is11 = SHOW_UBITS(re, &s->gb, 1);
499                 SKIP_CACHE(re, &s->gb, 1);
500                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
501                 if (is11) {
502                     SKIP_COUNTER(re, &s->gb, 1 + 7);
503                     UPDATE_CACHE(re, &s->gb);
504                     level = SHOW_SBITS(re, &s->gb, 11);
505                     SKIP_COUNTER(re, &s->gb, 11);
506                 } else {
507                     SKIP_CACHE(re, &s->gb, 7);
508                     level = SHOW_SBITS(re, &s->gb, 7);
509                     SKIP_COUNTER(re, &s->gb, 1 + 7 + 7);
510                 }
511             } else {
512                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
513                 SKIP_CACHE(re, &s->gb, 7);
514                 level = (int8_t)SHOW_UBITS(re, &s->gb, 8);
515                 SKIP_COUNTER(re, &s->gb, 7 + 8);
516                 if(level == -128){
517                     UPDATE_CACHE(re, &s->gb);
518                     if (s->codec_id == AV_CODEC_ID_RV10) {
519                         /* XXX: should patch encoder too */
520                         level = SHOW_SBITS(re, &s->gb, 12);
521                         SKIP_COUNTER(re, &s->gb, 12);
522                     }else{
523                         level = SHOW_UBITS(re, &s->gb, 5);
524                         SKIP_CACHE(re, &s->gb, 5);
525                         level |= SHOW_SBITS(re, &s->gb, 6)<<5;
526                         SKIP_COUNTER(re, &s->gb, 5 + 6);
527                     }
528                 }
529             }
530         } else {
531             if (SHOW_UBITS(re, &s->gb, 1))
532                 level = -level;
533             SKIP_COUNTER(re, &s->gb, 1);
534         }
535         i += run;
536         if (i >= 64){
537             CLOSE_READER(re, &s->gb);
538             // redo update without last flag, revert -1 offset
539             i = i - run + ((run-1)&63) + 1;
540             if (i < 64) {
541                 // only last marker, no overrun
542                 block[scan_table[i]] = level;
543                 break;
544             }
545             if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
546                 //Looks like a hack but no, it's the way it is supposed to work ...
547                 rl = &ff_rl_intra_aic;
548                 i = 0;
549                 s->gb= gb;
550                 s->bdsp.clear_block(block);
551                 goto retry;
552             }
553             av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
554             return -1;
555         }
556         j = scan_table[i];
557         block[j] = level;
558     }
559     }
560 not_coded:
561     if (s->mb_intra && s->h263_aic) {
562         ff_h263_pred_acdc(s, block, n);
563         i = 63;
564     }
565     s->block_last_index[n] = i;
566     return 0;
567 }
568
569 static int h263_skip_b_part(MpegEncContext *s, int cbp)
570 {
571     LOCAL_ALIGNED_16(int16_t, dblock, [64]);
572     int i, mbi;
573     int bli[6];
574
575     /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
576      * but real value should be restored in order to be used later (in OBMC condition)
577      */
578     mbi = s->mb_intra;
579     memcpy(bli, s->block_last_index, sizeof(bli));
580     s->mb_intra = 0;
581     for (i = 0; i < 6; i++) {
582         if (h263_decode_block(s, dblock, i, cbp&32) < 0)
583             return -1;
584         cbp+=cbp;
585     }
586     s->mb_intra = mbi;
587     memcpy(s->block_last_index, bli, sizeof(bli));
588     return 0;
589 }
590
591 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
592 {
593     int c, mv = 1;
594
595     if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
596         c = get_bits1(gb);
597         if (pb_frame == 2 && c)
598             mv = !get_bits1(gb);
599     } else { // h.263 Annex M improved PB-frame
600         mv = get_unary(gb, 0, 4) + 1;
601         c = mv & 1;
602         mv = !!(mv & 2);
603     }
604     if(c)
605         *cbpb = get_bits(gb, 6);
606     return mv;
607 }
608
609 int ff_h263_decode_mb(MpegEncContext *s,
610                       int16_t block[6][64])
611 {
612     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
613     int16_t *mot_val;
614     const int xy= s->mb_x + s->mb_y * s->mb_stride;
615     int cbpb = 0, pb_mv_count = 0;
616
617     av_assert2(!s->h263_pred);
618
619     if (s->pict_type == AV_PICTURE_TYPE_P) {
620         do{
621             if (get_bits1(&s->gb)) {
622                 /* skip mb */
623                 s->mb_intra = 0;
624                 for(i=0;i<6;i++)
625                     s->block_last_index[i] = -1;
626                 s->mv_dir = MV_DIR_FORWARD;
627                 s->mv_type = MV_TYPE_16X16;
628                 s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
629                 s->mv[0][0][0] = 0;
630                 s->mv[0][0][1] = 0;
631                 s->mb_skipped = !(s->obmc | s->loop_filter);
632                 goto end;
633             }
634             cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
635             if (cbpc < 0){
636                 av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
637                 return -1;
638             }
639         }while(cbpc == 20);
640
641         s->bdsp.clear_blocks(s->block[0]);
642
643         dquant = cbpc & 8;
644         s->mb_intra = ((cbpc & 4) != 0);
645         if (s->mb_intra) goto intra;
646
647         if(s->pb_frame && get_bits1(&s->gb))
648             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
649         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
650
651         if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
652             cbpy ^= 0xF;
653
654         cbp = (cbpc & 3) | (cbpy << 2);
655         if (dquant) {
656             h263_decode_dquant(s);
657         }
658
659         s->mv_dir = MV_DIR_FORWARD;
660         if ((cbpc & 16) == 0) {
661             s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
662             /* 16x16 motion prediction */
663             s->mv_type = MV_TYPE_16X16;
664             ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
665             if (s->umvplus)
666                mx = h263p_decode_umotion(s, pred_x);
667             else
668                mx = ff_h263_decode_motion(s, pred_x, 1);
669
670             if (mx >= 0xffff)
671                 return -1;
672
673             if (s->umvplus)
674                my = h263p_decode_umotion(s, pred_y);
675             else
676                my = ff_h263_decode_motion(s, pred_y, 1);
677
678             if (my >= 0xffff)
679                 return -1;
680             s->mv[0][0][0] = mx;
681             s->mv[0][0][1] = my;
682
683             if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
684                skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
685         } else {
686             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
687             s->mv_type = MV_TYPE_8X8;
688             for(i=0;i<4;i++) {
689                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
690                 if (s->umvplus)
691                   mx = h263p_decode_umotion(s, pred_x);
692                 else
693                   mx = ff_h263_decode_motion(s, pred_x, 1);
694                 if (mx >= 0xffff)
695                     return -1;
696
697                 if (s->umvplus)
698                   my = h263p_decode_umotion(s, pred_y);
699                 else
700                   my = ff_h263_decode_motion(s, pred_y, 1);
701                 if (my >= 0xffff)
702                     return -1;
703                 s->mv[0][i][0] = mx;
704                 s->mv[0][i][1] = my;
705                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
706                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
707                 mot_val[0] = mx;
708                 mot_val[1] = my;
709             }
710         }
711     } else if(s->pict_type==AV_PICTURE_TYPE_B) {
712         int mb_type;
713         const int stride= s->b8_stride;
714         int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
715         int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
716 //        const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
717
718         //FIXME ugly
719         mot_val0[0       ]= mot_val0[2       ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
720         mot_val0[1       ]= mot_val0[3       ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
721         mot_val1[0       ]= mot_val1[2       ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
722         mot_val1[1       ]= mot_val1[3       ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
723
724         do{
725             mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
726             if (mb_type < 0){
727                 av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
728                 return -1;
729             }
730
731             mb_type= h263_mb_type_b_map[ mb_type ];
732         }while(!mb_type);
733
734         s->mb_intra = IS_INTRA(mb_type);
735         if(HAS_CBP(mb_type)){
736             s->bdsp.clear_blocks(s->block[0]);
737             cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
738             if(s->mb_intra){
739                 dquant = IS_QUANT(mb_type);
740                 goto intra;
741             }
742
743             cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
744
745             if (cbpy < 0){
746                 av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
747                 return -1;
748             }
749
750             if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
751                 cbpy ^= 0xF;
752
753             cbp = (cbpc & 3) | (cbpy << 2);
754         }else
755             cbp=0;
756
757         av_assert2(!s->mb_intra);
758
759         if(IS_QUANT(mb_type)){
760             h263_decode_dquant(s);
761         }
762
763         if(IS_DIRECT(mb_type)){
764             s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
765             mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
766         }else{
767             s->mv_dir = 0;
768             s->mv_type= MV_TYPE_16X16;
769 //FIXME UMV
770
771             if(USES_LIST(mb_type, 0)){
772                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
773                 s->mv_dir = MV_DIR_FORWARD;
774
775                 mx = ff_h263_decode_motion(s, mx, 1);
776                 my = ff_h263_decode_motion(s, my, 1);
777
778                 s->mv[0][0][0] = mx;
779                 s->mv[0][0][1] = my;
780                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
781                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
782             }
783
784             if(USES_LIST(mb_type, 1)){
785                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
786                 s->mv_dir |= MV_DIR_BACKWARD;
787
788                 mx = ff_h263_decode_motion(s, mx, 1);
789                 my = ff_h263_decode_motion(s, my, 1);
790
791                 s->mv[1][0][0] = mx;
792                 s->mv[1][0][1] = my;
793                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
794                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
795             }
796         }
797
798         s->current_picture.mb_type[xy] = mb_type;
799     } else { /* I-Frame */
800         do{
801             cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
802             if (cbpc < 0){
803                 av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
804                 return -1;
805             }
806         }while(cbpc == 8);
807
808         s->bdsp.clear_blocks(s->block[0]);
809
810         dquant = cbpc & 4;
811         s->mb_intra = 1;
812 intra:
813         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
814         if (s->h263_aic) {
815             s->ac_pred = get_bits1(&s->gb);
816             if(s->ac_pred){
817                 s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
818
819                 s->h263_aic_dir = get_bits1(&s->gb);
820             }
821         }else
822             s->ac_pred = 0;
823
824         if(s->pb_frame && get_bits1(&s->gb))
825             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
826         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
827         if(cbpy<0){
828             av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
829             return -1;
830         }
831         cbp = (cbpc & 3) | (cbpy << 2);
832         if (dquant) {
833             h263_decode_dquant(s);
834         }
835
836         pb_mv_count += !!s->pb_frame;
837     }
838
839     while(pb_mv_count--){
840         ff_h263_decode_motion(s, 0, 1);
841         ff_h263_decode_motion(s, 0, 1);
842     }
843
844     /* decode each block */
845     for (i = 0; i < 6; i++) {
846         if (h263_decode_block(s, block[i], i, cbp&32) < 0)
847             return -1;
848         cbp+=cbp;
849     }
850
851     if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
852         return -1;
853     if(s->obmc && !s->mb_intra){
854         if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
855             preview_obmc(s);
856     }
857 end:
858
859         /* per-MB end of slice check */
860     {
861         int v= show_bits(&s->gb, 16);
862
863         if (get_bits_left(&s->gb) < 16) {
864             v >>= 16 - get_bits_left(&s->gb);
865         }
866
867         if(v==0)
868             return SLICE_END;
869     }
870
871     return SLICE_OK;
872 }
873
874 /* most is hardcoded. should extend to handle all h263 streams */
875 int ff_h263_decode_picture_header(MpegEncContext *s)
876 {
877     int format, width, height, i;
878     uint32_t startcode;
879
880     align_get_bits(&s->gb);
881
882     if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
883          av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
884     }
885
886     startcode= get_bits(&s->gb, 22-8);
887
888     for(i= get_bits_left(&s->gb); i>24; i-=8) {
889         startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
890
891         if(startcode == 0x20)
892             break;
893     }
894
895     if (startcode != 0x20) {
896         av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
897         return -1;
898     }
899     /* temporal reference */
900     i = get_bits(&s->gb, 8); /* picture timestamp */
901     if( (s->picture_number&~0xFF)+i < s->picture_number)
902         i+= 256;
903     s->picture_number= (s->picture_number&~0xFF) + i;
904
905     /* PTYPE starts here */
906     if (check_marker(&s->gb, "in PTYPE") != 1) {
907         return -1;
908     }
909     if (get_bits1(&s->gb) != 0) {
910         av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
911         return -1;      /* h263 id */
912     }
913     skip_bits1(&s->gb);         /* split screen off */
914     skip_bits1(&s->gb);         /* camera  off */
915     skip_bits1(&s->gb);         /* freeze picture release off */
916
917     format = get_bits(&s->gb, 3);
918     /*
919         0    forbidden
920         1    sub-QCIF
921         10   QCIF
922         7       extended PTYPE (PLUSPTYPE)
923     */
924
925     if (format != 7 && format != 6) {
926         s->h263_plus = 0;
927         /* H.263v1 */
928         width = ff_h263_format[format][0];
929         height = ff_h263_format[format][1];
930         if (!width)
931             return -1;
932
933         s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
934
935         s->h263_long_vectors = get_bits1(&s->gb);
936
937         if (get_bits1(&s->gb) != 0) {
938             av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
939             return -1; /* SAC: off */
940         }
941         s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
942         s->unrestricted_mv = s->h263_long_vectors || s->obmc;
943
944         s->pb_frame = get_bits1(&s->gb);
945         s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
946         skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
947
948         s->width = width;
949         s->height = height;
950         s->avctx->sample_aspect_ratio= (AVRational){12,11};
951         s->avctx->framerate = (AVRational){ 30000, 1001 };
952     } else {
953         int ufep;
954
955         /* H.263v2 */
956         s->h263_plus = 1;
957         ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
958
959         /* ufep other than 0 and 1 are reserved */
960         if (ufep == 1) {
961             /* OPPTYPE */
962             format = get_bits(&s->gb, 3);
963             ff_dlog(s->avctx, "ufep=1, format: %d\n", format);
964             s->custom_pcf= get_bits1(&s->gb);
965             s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
966             if (get_bits1(&s->gb) != 0) {
967                 av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
968             }
969             s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
970             s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
971             s->loop_filter= get_bits1(&s->gb);
972             s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
973             if(s->avctx->lowres)
974                 s->loop_filter = 0;
975
976             s->h263_slice_structured= get_bits1(&s->gb);
977             if (get_bits1(&s->gb) != 0) {
978                 av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
979             }
980             if (get_bits1(&s->gb) != 0) {
981                 av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
982             }
983             s->alt_inter_vlc= get_bits1(&s->gb);
984             s->modified_quant= get_bits1(&s->gb);
985             if(s->modified_quant)
986                 s->chroma_qscale_table= ff_h263_chroma_qscale_table;
987
988             skip_bits(&s->gb, 1); /* Prevent start code emulation */
989
990             skip_bits(&s->gb, 3); /* Reserved */
991         } else if (ufep != 0) {
992             av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
993             return -1;
994         }
995
996         /* MPPTYPE */
997         s->pict_type = get_bits(&s->gb, 3);
998         switch(s->pict_type){
999         case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
1000         case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
1001         case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
1002         case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
1003         case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
1004         default:
1005             return -1;
1006         }
1007         skip_bits(&s->gb, 2);
1008         s->no_rounding = get_bits1(&s->gb);
1009         skip_bits(&s->gb, 4);
1010
1011         /* Get the picture dimensions */
1012         if (ufep) {
1013             if (format == 6) {
1014                 /* Custom Picture Format (CPFMT) */
1015                 s->aspect_ratio_info = get_bits(&s->gb, 4);
1016                 ff_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1017                 /* aspect ratios:
1018                 0 - forbidden
1019                 1 - 1:1
1020                 2 - 12:11 (CIF 4:3)
1021                 3 - 10:11 (525-type 4:3)
1022                 4 - 16:11 (CIF 16:9)
1023                 5 - 40:33 (525-type 16:9)
1024                 6-14 - reserved
1025                 */
1026                 width = (get_bits(&s->gb, 9) + 1) * 4;
1027                 check_marker(&s->gb, "in dimensions");
1028                 height = get_bits(&s->gb, 9) * 4;
1029                 ff_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1030                 if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1031                     /* aspected dimensions */
1032                     s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1033                     s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1034                 }else{
1035                     s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
1036                 }
1037             } else {
1038                 width = ff_h263_format[format][0];
1039                 height = ff_h263_format[format][1];
1040                 s->avctx->sample_aspect_ratio= (AVRational){12,11};
1041             }
1042             s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
1043             if ((width == 0) || (height == 0))
1044                 return -1;
1045             s->width = width;
1046             s->height = height;
1047
1048             if(s->custom_pcf){
1049                 int gcd;
1050                 s->avctx->framerate.num  = 1800000;
1051                 s->avctx->framerate.den  = 1000 + get_bits1(&s->gb);
1052                 s->avctx->framerate.den *= get_bits(&s->gb, 7);
1053                 if(s->avctx->framerate.den == 0){
1054                     av_log(s, AV_LOG_ERROR, "zero framerate\n");
1055                     return -1;
1056                 }
1057                 gcd= av_gcd(s->avctx->framerate.den, s->avctx->framerate.num);
1058                 s->avctx->framerate.den /= gcd;
1059                 s->avctx->framerate.num /= gcd;
1060             }else{
1061                 s->avctx->framerate = (AVRational){ 30000, 1001 };
1062             }
1063         }
1064
1065         if(s->custom_pcf){
1066             skip_bits(&s->gb, 2); //extended Temporal reference
1067         }
1068
1069         if (ufep) {
1070             if (s->umvplus) {
1071                 if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1072                     skip_bits1(&s->gb);
1073             }
1074             if(s->h263_slice_structured){
1075                 if (get_bits1(&s->gb) != 0) {
1076                     av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1077                 }
1078                 if (get_bits1(&s->gb) != 0) {
1079                     av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1080                 }
1081             }
1082         }
1083
1084         s->qscale = get_bits(&s->gb, 5);
1085     }
1086
1087     if (s->width == 0 || s->height == 0) {
1088         av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1089         return -1;
1090     }
1091     s->mb_width = (s->width  + 15) / 16;
1092     s->mb_height = (s->height  + 15) / 16;
1093     s->mb_num = s->mb_width * s->mb_height;
1094
1095     if (s->pb_frame) {
1096         skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1097         if (s->custom_pcf)
1098             skip_bits(&s->gb, 2); //extended Temporal reference
1099         skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1100     }
1101
1102     if (s->pict_type!=AV_PICTURE_TYPE_B) {
1103         s->time            = s->picture_number;
1104         s->pp_time         = s->time - s->last_non_b_time;
1105         s->last_non_b_time = s->time;
1106     }else{
1107         s->time    = s->picture_number;
1108         s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1109         if (s->pp_time <=s->pb_time ||
1110             s->pp_time <= s->pp_time - s->pb_time ||
1111             s->pp_time <= 0){
1112             s->pp_time = 2;
1113             s->pb_time = 1;
1114         }
1115         ff_mpeg4_init_direct_mv(s);
1116     }
1117
1118     /* PEI */
1119     if (skip_1stop_8data_bits(&s->gb) < 0)
1120         return AVERROR_INVALIDDATA;
1121
1122     if(s->h263_slice_structured){
1123         if (check_marker(&s->gb, "SEPB1") != 1) {
1124             return -1;
1125         }
1126
1127         ff_h263_decode_mba(s);
1128
1129         if (check_marker(&s->gb, "SEPB2") != 1) {
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 }