a1a7f14f5613e079cd52dd07e05ccd8433c29558
[libav.git] / libavcodec / h261.c
1 /*
2 * H261 decoder
3 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2004 Maarten Daniels
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file h261.c
23 * h261codec.
24 */
25
26 #include "common.h"
27 #include "dsputil.h"
28 #include "avcodec.h"
29 #include "mpegvideo.h"
30 #include "h261data.h"
31
32
33 #define H261_MBA_VLC_BITS 9
34 #define H261_MTYPE_VLC_BITS 6
35 #define H261_MV_VLC_BITS 7
36 #define H261_CBP_VLC_BITS 9
37 #define TCOEFF_VLC_BITS 9
38
39 #define MBA_STUFFING 33
40 #define MBA_STARTCODE 34
41 #define IS_FIL(a) ((a)&MB_TYPE_H261_FIL)
42
43 /**
44 * H261Context
45 */
46 typedef struct H261Context{
47 MpegEncContext s;
48
49 int current_mba;
50 int previous_mba;
51 int mba_diff;
52 int mtype;
53 int current_mv_x;
54 int current_mv_y;
55 int gob_number;
56 int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
57 }H261Context;
58
59 void ff_h261_loop_filter(MpegEncContext *s){
60 H261Context * h= (H261Context*)s;
61 const int linesize = s->linesize;
62 const int uvlinesize= s->uvlinesize;
63 uint8_t *dest_y = s->dest[0];
64 uint8_t *dest_cb= s->dest[1];
65 uint8_t *dest_cr= s->dest[2];
66
67 if(!(IS_FIL (h->mtype)))
68 return;
69
70 s->dsp.h261_loop_filter(dest_y , linesize);
71 s->dsp.h261_loop_filter(dest_y + 8, linesize);
72 s->dsp.h261_loop_filter(dest_y + 8 * linesize , linesize);
73 s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
74 s->dsp.h261_loop_filter(dest_cb, uvlinesize);
75 s->dsp.h261_loop_filter(dest_cr, uvlinesize);
76 }
77
78 static int ff_h261_get_picture_format(int width, int height){
79 // QCIF
80 if (width == 176 && height == 144)
81 return 0;
82 // CIF
83 else if (width == 352 && height == 288)
84 return 1;
85 // ERROR
86 else
87 return -1;
88 }
89
90 static void h261_encode_block(H261Context * h, DCTELEM * block,
91 int n);
92 static int h261_decode_block(H261Context *h, DCTELEM *block,
93 int n, int coded);
94
95 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
96 H261Context * h = (H261Context *) s;
97 int format, temp_ref;
98
99 align_put_bits(&s->pb);
100
101 /* Update the pointer to last GOB */
102 s->ptr_lastgob = pbBufPtr(&s->pb);
103
104 put_bits(&s->pb, 20, 0x10); /* PSC */
105
106 temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
107 (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
108 put_bits(&s->pb, 5, temp_ref & 0x1f); /* TemporalReference */
109
110 put_bits(&s->pb, 1, 0); /* split screen off */
111 put_bits(&s->pb, 1, 0); /* camera off */
112 put_bits(&s->pb, 1, 0); /* freeze picture release off */
113
114 format = ff_h261_get_picture_format(s->width, s->height);
115
116 put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
117
118 put_bits(&s->pb, 1, 0); /* still image mode */
119 put_bits(&s->pb, 1, 0); /* reserved */
120
121 put_bits(&s->pb, 1, 0); /* no PEI */
122 if(format == 0)
123 h->gob_number = -1;
124 else
125 h->gob_number = 0;
126 h->current_mba = 0;
127 }
128
129 /**
130 * Encodes a group of blocks header.
131 */
132 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
133 H261Context * h = (H261Context *)s;
134 if(ff_h261_get_picture_format(s->width, s->height) == 0){
135 h->gob_number+=2; // QCIF
136 }
137 else{
138 h->gob_number++; // CIF
139 }
140 put_bits(&s->pb, 16, 1); /* GBSC */
141 put_bits(&s->pb, 4, h->gob_number); /* GN */
142 put_bits(&s->pb, 5, s->qscale); /* GQUANT */
143 put_bits(&s->pb, 1, 0); /* no GEI */
144 h->current_mba = 0;
145 h->previous_mba = 0;
146 h->current_mv_x=0;
147 h->current_mv_y=0;
148 }
149
150 void ff_h261_reorder_mb_index(MpegEncContext* s){
151 int index= s->mb_x + s->mb_y*s->mb_width;
152
153 if(index % 33 == 0)
154 h261_encode_gob_header(s,0);
155
156 /* for CIF the GOB's are fragmented in the middle of a scanline
157 that's why we need to adjust the x and y index of the macroblocks */
158 if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
159 s->mb_x = index % 11 ; index /= 11;
160 s->mb_y = index % 3 ; index /= 3;
161 s->mb_x+= 11*(index % 2); index /= 2;
162 s->mb_y+= 3*index;
163
164 ff_init_block_index(s);
165 ff_update_block_index(s);
166 }
167 }
168
169 static void h261_encode_motion(H261Context * h, int val){
170 MpegEncContext * const s = &h->s;
171 int sign, code;
172 if(val==0){
173 code = 0;
174 put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
175 }
176 else{
177 if(val > 15)
178 val -=32;
179 if(val < -16)
180 val+=32;
181 sign = val < 0;
182 code = sign ? -val : val;
183 put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
184 put_bits(&s->pb,1,sign);
185 }
186 }
187
188 static inline int get_cbp(MpegEncContext * s,
189 DCTELEM block[6][64])
190 {
191 int i, cbp;
192 cbp= 0;
193 for (i = 0; i < 6; i++) {
194 if (s->block_last_index[i] >= 0)
195 cbp |= 1 << (5 - i);
196 }
197 return cbp;
198 }
199 void ff_h261_encode_mb(MpegEncContext * s,
200 DCTELEM block[6][64],
201 int motion_x, int motion_y)
202 {
203 H261Context * h = (H261Context *)s;
204 int mvd, mv_diff_x, mv_diff_y, i, cbp;
205 cbp = 63; // avoid warning
206 mvd = 0;
207
208 h->current_mba++;
209 h->mtype = 0;
210
211 if (!s->mb_intra){
212 /* compute cbp */
213 cbp= get_cbp(s, block);
214
215 /* mvd indicates if this block is motion compensated */
216 mvd = motion_x | motion_y;
217
218 if((cbp | mvd | s->dquant ) == 0) {
219 /* skip macroblock */
220 s->skip_count++;
221 h->current_mv_x=0;
222 h->current_mv_y=0;
223 return;
224 }
225 }
226
227 /* MB is not skipped, encode MBA */
228 put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
229
230 /* calculate MTYPE */
231 if(!s->mb_intra){
232 h->mtype++;
233
234 if(mvd || s->loop_filter)
235 h->mtype+=3;
236 if(s->loop_filter)
237 h->mtype+=3;
238 if(cbp || s->dquant)
239 h->mtype++;
240 assert(h->mtype > 1);
241 }
242
243 if(s->dquant)
244 h->mtype++;
245
246 put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
247
248 h->mtype = h261_mtype_map[h->mtype];
249
250 if(IS_QUANT(h->mtype)){
251 ff_set_qscale(s,s->qscale+s->dquant);
252 put_bits(&s->pb, 5, s->qscale);
253 }
254
255 if(IS_16X16(h->mtype)){
256 mv_diff_x = (motion_x >> 1) - h->current_mv_x;
257 mv_diff_y = (motion_y >> 1) - h->current_mv_y;
258 h->current_mv_x = (motion_x >> 1);
259 h->current_mv_y = (motion_y >> 1);
260 h261_encode_motion(h,mv_diff_x);
261 h261_encode_motion(h,mv_diff_y);
262 }
263
264 h->previous_mba = h->current_mba;
265
266 if(HAS_CBP(h->mtype)){
267 assert(cbp>0);
268 put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
269 }
270 for(i=0; i<6; i++) {
271 /* encode each block */
272 h261_encode_block(h, block[i], i);
273 }
274
275 if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
276 h->current_mv_x=0;
277 h->current_mv_y=0;
278 }
279 }
280
281 void ff_h261_encode_init(MpegEncContext *s){
282 static int done = 0;
283
284 if (!done) {
285 done = 1;
286 init_rl(&h261_rl_tcoeff, 1);
287 }
288
289 s->min_qcoeff= -127;
290 s->max_qcoeff= 127;
291 s->y_dc_scale_table=
292 s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
293 }
294
295
296 /**
297 * encodes a 8x8 block.
298 * @param block the 8x8 block
299 * @param n block index (0-3 are luma, 4-5 are chroma)
300 */
301 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
302 MpegEncContext * const s = &h->s;
303 int level, run, last, i, j, last_index, last_non_zero, sign, slevel, code;
304 RLTable *rl;
305
306 rl = &h261_rl_tcoeff;
307 if (s->mb_intra) {
308 /* DC coef */
309 level = block[0];
310 /* 255 cannot be represented, so we clamp */
311 if (level > 254) {
312 level = 254;
313 block[0] = 254;
314 }
315 /* 0 cannot be represented also */
316 else if (level < 1) {
317 level = 1;
318 block[0] = 1;
319 }
320 if (level == 128)
321 put_bits(&s->pb, 8, 0xff);
322 else
323 put_bits(&s->pb, 8, level);
324 i = 1;
325 } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
326 //special case
327 put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
328 i = 1;
329 } else {
330 i = 0;
331 }
332
333 /* AC coefs */
334 last_index = s->block_last_index[n];
335 last_non_zero = i - 1;
336 for (; i <= last_index; i++) {
337 j = s->intra_scantable.permutated[i];
338 level = block[j];
339 if (level) {
340 run = i - last_non_zero - 1;
341 last = (i == last_index);
342 sign = 0;
343 slevel = level;
344 if (level < 0) {
345 sign = 1;
346 level = -level;
347 }
348 code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
349 if(run==0 && level < 16)
350 code+=1;
351 put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
352 if (code == rl->n) {
353 put_bits(&s->pb, 6, run);
354 assert(slevel != 0);
355 assert(level <= 127);
356 put_bits(&s->pb, 8, slevel & 0xff);
357 } else {
358 put_bits(&s->pb, 1, sign);
359 }
360 last_non_zero = i;
361 }
362 }
363 if(last_index > -1){
364 put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
365 }
366 }
367
368 /***********************************************/
369 /* decoding */
370
371 static VLC h261_mba_vlc;
372 static VLC h261_mtype_vlc;
373 static VLC h261_mv_vlc;
374 static VLC h261_cbp_vlc;
375
376 void init_vlc_rl(RLTable *rl, int use_static);
377
378 static void h261_decode_init_vlc(H261Context *h){
379 static int done = 0;
380
381 if(!done){
382 done = 1;
383 init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
384 h261_mba_bits, 1, 1,
385 h261_mba_code, 1, 1, 1);
386 init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
387 h261_mtype_bits, 1, 1,
388 h261_mtype_code, 1, 1, 1);
389 init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
390 &h261_mv_tab[0][1], 2, 1,
391 &h261_mv_tab[0][0], 2, 1, 1);
392 init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
393 &h261_cbp_tab[0][1], 2, 1,
394 &h261_cbp_tab[0][0], 2, 1, 1);
395 init_rl(&h261_rl_tcoeff, 1);
396 init_vlc_rl(&h261_rl_tcoeff, 1);
397 }
398 }
399
400 static int h261_decode_init(AVCodecContext *avctx){
401 H261Context *h= avctx->priv_data;
402 MpegEncContext * const s = &h->s;
403
404 // set defaults
405 MPV_decode_defaults(s);
406 s->avctx = avctx;
407
408 s->width = s->avctx->coded_width;
409 s->height = s->avctx->coded_height;
410 s->codec_id = s->avctx->codec->id;
411
412 s->out_format = FMT_H261;
413 s->low_delay= 1;
414 avctx->pix_fmt= PIX_FMT_YUV420P;
415
416 s->codec_id= avctx->codec->id;
417
418 h261_decode_init_vlc(h);
419
420 h->gob_start_code_skipped = 0;
421
422 return 0;
423 }
424
425 /**
426 * decodes the group of blocks header or slice header.
427 * @return <0 if an error occured
428 */
429 static int h261_decode_gob_header(H261Context *h){
430 unsigned int val;
431 MpegEncContext * const s = &h->s;
432
433 if ( !h->gob_start_code_skipped ){
434 /* Check for GOB Start Code */
435 val = show_bits(&s->gb, 15);
436 if(val)
437 return -1;
438
439 /* We have a GBSC */
440 skip_bits(&s->gb, 16);
441 }
442
443 h->gob_start_code_skipped = 0;
444
445 h->gob_number = get_bits(&s->gb, 4); /* GN */
446 s->qscale = get_bits(&s->gb, 5); /* GQUANT */
447
448 /* Check if gob_number is valid */
449 if (s->mb_height==18){ //cif
450 if ((h->gob_number<=0) || (h->gob_number>12))
451 return -1;
452 }
453 else{ //qcif
454 if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
455 return -1;
456 }
457
458 /* GEI */
459 while (get_bits1(&s->gb) != 0) {
460 skip_bits(&s->gb, 8);
461 }
462
463 if(s->qscale==0)
464 return -1;
465
466 // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
467 // subsequent macroblocks, MBA is the difference between the absolute addresses of
468 // the macroblock and the last transmitted macroblock.
469 h->current_mba = 0;
470 h->mba_diff = 0;
471
472 return 0;
473 }
474
475 /**
476 * decodes the group of blocks / video packet header.
477 * @return <0 if no resync found
478 */
479 static int ff_h261_resync(H261Context *h){
480 MpegEncContext * const s = &h->s;
481 int left, ret;
482
483 if ( h->gob_start_code_skipped ){
484 ret= h261_decode_gob_header(h);
485 if(ret>=0)
486 return 0;
487 }
488 else{
489 if(show_bits(&s->gb, 15)==0){
490 ret= h261_decode_gob_header(h);
491 if(ret>=0)
492 return 0;
493 }
494 //ok, its not where its supposed to be ...
495 s->gb= s->last_resync_gb;
496 align_get_bits(&s->gb);
497 left= s->gb.size_in_bits - get_bits_count(&s->gb);
498
499 for(;left>15+1+4+5; left-=8){
500 if(show_bits(&s->gb, 15)==0){
501 GetBitContext bak= s->gb;
502
503 ret= h261_decode_gob_header(h);
504 if(ret>=0)
505 return 0;
506
507 s->gb= bak;
508 }
509 skip_bits(&s->gb, 8);
510 }
511 }
512
513 return -1;
514 }
515
516 /**
517 * decodes skipped macroblocks
518 * @return 0
519 */
520 static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
521 {
522 MpegEncContext * const s = &h->s;
523 int i;
524
525 s->mb_intra = 0;
526
527 for(i=mba1; i<mba2; i++){
528 int j, xy;
529
530 s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
531 s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
532 xy = s->mb_x + s->mb_y * s->mb_stride;
533 ff_init_block_index(s);
534 ff_update_block_index(s);
535
536 for(j=0;j<6;j++)
537 s->block_last_index[j] = -1;
538
539 s->mv_dir = MV_DIR_FORWARD;
540 s->mv_type = MV_TYPE_16X16;
541 s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
542 s->mv[0][0][0] = 0;
543 s->mv[0][0][1] = 0;
544 s->mb_skipped = 1;
545 h->mtype &= ~MB_TYPE_H261_FIL;
546
547 MPV_decode_mb(s, s->block);
548 }
549
550 return 0;
551 }
552
553 static int decode_mv_component(GetBitContext *gb, int v){
554 int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
555
556 /* check if mv_diff is valid */
557 if ( mv_diff < 0 )
558 return v;
559
560 mv_diff = mvmap[mv_diff];
561
562 if(mv_diff && !get_bits1(gb))
563 mv_diff= -mv_diff;
564
565 v += mv_diff;
566 if (v <=-16) v+= 32;
567 else if(v >= 16) v-= 32;
568
569 return v;
570 }
571
572 static int h261_decode_mb(H261Context *h){
573 MpegEncContext * const s = &h->s;
574 int i, cbp, xy;
575
576 cbp = 63;
577 // Read mba
578 do{
579 h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
580
581 /* Check for slice end */
582 /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
583 if (h->mba_diff == MBA_STARTCODE){ // start code
584 h->gob_start_code_skipped = 1;
585 return SLICE_END;
586 }
587 }
588 while( h->mba_diff == MBA_STUFFING ); // stuffing
589
590 if ( h->mba_diff < 0 ){
591 if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
592 return SLICE_END;
593
594 av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
595 return SLICE_ERROR;
596 }
597
598 h->mba_diff += 1;
599 h->current_mba += h->mba_diff;
600
601 if ( h->current_mba > MBA_STUFFING )
602 return SLICE_ERROR;
603
604 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
605 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
606 xy = s->mb_x + s->mb_y * s->mb_stride;
607 ff_init_block_index(s);
608 ff_update_block_index(s);
609
610 // Read mtype
611 h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
612 h->mtype = h261_mtype_map[h->mtype];
613
614 // Read mquant
615 if ( IS_QUANT ( h->mtype ) ){
616 ff_set_qscale(s, get_bits(&s->gb, 5));
617 }
618
619 s->mb_intra = IS_INTRA4x4(h->mtype);
620
621 // Read mv
622 if ( IS_16X16 ( h->mtype ) ){
623 // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
624 // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
625 // following three situations:
626 // 1) evaluating MVD for macroblocks 1, 12 and 23;
627 // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
628 // 3) MTYPE of the previous macroblock was not MC.
629 if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
630 ( h->mba_diff != 1))
631 {
632 h->current_mv_x = 0;
633 h->current_mv_y = 0;
634 }
635
636 h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
637 h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
638 }else{
639 h->current_mv_x = 0;
640 h->current_mv_y = 0;
641 }
642
643 // Read cbp
644 if ( HAS_CBP( h->mtype ) ){
645 cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
646 }
647
648 if(s->mb_intra){
649 s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
650 goto intra;
651 }
652
653 //set motion vectors
654 s->mv_dir = MV_DIR_FORWARD;
655 s->mv_type = MV_TYPE_16X16;
656 s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
657 s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
658 s->mv[0][0][1] = h->current_mv_y * 2;
659
660 intra:
661 /* decode each block */
662 if(s->mb_intra || HAS_CBP(h->mtype)){
663 s->dsp.clear_blocks(s->block[0]);
664 for (i = 0; i < 6; i++) {
665 if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
666 return SLICE_ERROR;
667 }
668 cbp+=cbp;
669 }
670 }else{
671 for (i = 0; i < 6; i++)
672 s->block_last_index[i]= -1;
673 }
674
675 MPV_decode_mb(s, s->block);
676
677 return SLICE_OK;
678 }
679
680 /**
681 * decodes a macroblock
682 * @return <0 if an error occured
683 */
684 static int h261_decode_block(H261Context * h, DCTELEM * block,
685 int n, int coded)
686 {
687 MpegEncContext * const s = &h->s;
688 int code, level, i, j, run;
689 RLTable *rl = &h261_rl_tcoeff;
690 const uint8_t *scan_table;
691
692 // For the variable length encoding there are two code tables, one being used for
693 // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
694 // for all other LEVELs except the first one in INTRA blocks which is fixed length
695 // coded with 8 bits.
696 // NOTE: the two code tables only differ in one VLC so we handle that manually.
697 scan_table = s->intra_scantable.permutated;
698 if (s->mb_intra){
699 /* DC coef */
700 level = get_bits(&s->gb, 8);
701 // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
702 if((level&0x7F) == 0){
703 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
704 return -1;
705 }
706 // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
707 if (level == 255)
708 level = 128;
709 block[0] = level;
710 i = 1;
711 }else if(coded){
712 // Run Level Code
713 // EOB Not possible for first level when cbp is available (that's why the table is different)
714 // 0 1 1s
715 // * * 0*
716 int check = show_bits(&s->gb, 2);
717 i = 0;
718 if ( check & 0x2 ){
719 skip_bits(&s->gb, 2);
720 block[0] = ( check & 0x1 ) ? -1 : 1;
721 i = 1;
722 }
723 }else{
724 i = 0;
725 }
726 if(!coded){
727 s->block_last_index[n] = i - 1;
728 return 0;
729 }
730 for(;;){
731 code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
732 if (code < 0){
733 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
734 return -1;
735 }
736 if (code == rl->n) {
737 /* escape */
738 // The remaining combinations of (run, level) are encoded with a 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits level.
739 run = get_bits(&s->gb, 6);
740 level = get_sbits(&s->gb, 8);
741 }else if(code == 0){
742 break;
743 }else{
744 run = rl->table_run[code];
745 level = rl->table_level[code];
746 if (get_bits1(&s->gb))
747 level = -level;
748 }
749 i += run;
750 if (i >= 64){
751 av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
752 return -1;
753 }
754 j = scan_table[i];
755 block[j] = level;
756 i++;
757 }
758 s->block_last_index[n] = i-1;
759 return 0;
760 }
761
762 /**
763 * decodes the H261 picture header.
764 * @return <0 if no startcode found
765 */
766 static int h261_decode_picture_header(H261Context *h){
767 MpegEncContext * const s = &h->s;
768 int format, i;
769 uint32_t startcode= 0;
770
771 for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
772 startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
773
774 if(startcode == 0x10)
775 break;
776 }
777
778 if (startcode != 0x10){
779 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
780 return -1;
781 }
782
783 /* temporal reference */
784 s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
785
786 /* PTYPE starts here */
787 skip_bits1(&s->gb); /* split screen off */
788 skip_bits1(&s->gb); /* camera off */
789 skip_bits1(&s->gb); /* freeze picture release off */
790
791 format = get_bits1(&s->gb);
792
793 //only 2 formats possible
794 if (format == 0){//QCIF
795 s->width = 176;
796 s->height = 144;
797 s->mb_width = 11;
798 s->mb_height = 9;
799 }else{//CIF
800 s->width = 352;
801 s->height = 288;
802 s->mb_width = 22;
803 s->mb_height = 18;
804 }
805
806 s->mb_num = s->mb_width * s->mb_height;
807
808 skip_bits1(&s->gb); /* still image mode off */
809 skip_bits1(&s->gb); /* Reserved */
810
811 /* PEI */
812 while (get_bits1(&s->gb) != 0){
813 skip_bits(&s->gb, 8);
814 }
815
816 // h261 has no I-FRAMES, but if we pass I_TYPE for the first frame, the codec crashes if it does
817 // not contain all I-blocks (e.g. when a packet is lost)
818 s->pict_type = P_TYPE;
819
820 h->gob_number = 0;
821 return 0;
822 }
823
824 static int h261_decode_gob(H261Context *h){
825 MpegEncContext * const s = &h->s;
826
827 ff_set_qscale(s, s->qscale);
828
829 /* decode mb's */
830 while(h->current_mba <= MBA_STUFFING)
831 {
832 int ret;
833 /* DCT & quantize */
834 ret= h261_decode_mb(h);
835 if(ret<0){
836 if(ret==SLICE_END){
837 h261_decode_mb_skipped(h, h->current_mba, 33);
838 return 0;
839 }
840 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
841 return -1;
842 }
843
844 h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
845 }
846
847 return -1;
848 }
849
850 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
851 int vop_found, i, j;
852 uint32_t state;
853
854 vop_found= pc->frame_start_found;
855 state= pc->state;
856
857 for(i=0; i<buf_size && !vop_found; i++){
858 state= (state<<8) | buf[i];
859 for(j=0; j<8; j++){
860 if(((state>>j)&0xFFFFF) == 0x00010){
861 i++;
862 vop_found=1;
863 break;
864 }
865 }
866 }
867 if(vop_found){
868 for(; i<buf_size; i++){
869 state= (state<<8) | buf[i];
870 for(j=0; j<8; j++){
871 if(((state>>j)&0xFFFFF) == 0x00010){
872 pc->frame_start_found=0;
873 pc->state= state>>(2*8);
874 return i-1;
875 }
876 }
877 }
878 }
879
880 pc->frame_start_found= vop_found;
881 pc->state= state;
882 return END_NOT_FOUND;
883 }
884
885 static int h261_parse(AVCodecParserContext *s,
886 AVCodecContext *avctx,
887 uint8_t **poutbuf, int *poutbuf_size,
888 const uint8_t *buf, int buf_size)
889 {
890 ParseContext *pc = s->priv_data;
891 int next;
892
893 next= h261_find_frame_end(pc,avctx, buf, buf_size);
894 if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
895 *poutbuf = NULL;
896 *poutbuf_size = 0;
897 return buf_size;
898 }
899 *poutbuf = (uint8_t *)buf;
900 *poutbuf_size = buf_size;
901 return next;
902 }
903
904 /**
905 * returns the number of bytes consumed for building the current frame
906 */
907 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
908 int pos= get_bits_count(&s->gb)>>3;
909 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
910 if(pos+10>buf_size) pos=buf_size; // oops ;)
911
912 return pos;
913 }
914
915 static int h261_decode_frame(AVCodecContext *avctx,
916 void *data, int *data_size,
917 uint8_t *buf, int buf_size)
918 {
919 H261Context *h= avctx->priv_data;
920 MpegEncContext *s = &h->s;
921 int ret;
922 AVFrame *pict = data;
923
924 #ifdef DEBUG
925 av_log(avctx, AV_LOG_DEBUG, "*****frame %d size=%d\n", avctx->frame_number, buf_size);
926 av_log(avctx, AV_LOG_DEBUG, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
927 #endif
928 s->flags= avctx->flags;
929 s->flags2= avctx->flags2;
930
931 h->gob_start_code_skipped=0;
932
933 retry:
934
935 init_get_bits(&s->gb, buf, buf_size*8);
936
937 if(!s->context_initialized){
938 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
939 return -1;
940 }
941
942 //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
943 if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
944 int i= ff_find_unused_picture(s, 0);
945 s->current_picture_ptr= &s->picture[i];
946 }
947
948 ret = h261_decode_picture_header(h);
949
950 /* skip if the header was thrashed */
951 if (ret < 0){
952 av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
953 return -1;
954 }
955
956 if (s->width != avctx->coded_width || s->height != avctx->coded_height){
957 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
958 s->parse_context.buffer=0;
959 MPV_common_end(s);
960 s->parse_context= pc;
961 }
962 if (!s->context_initialized) {
963 avcodec_set_dimensions(avctx, s->width, s->height);
964
965 goto retry;
966 }
967
968 // for hurry_up==5
969 s->current_picture.pict_type= s->pict_type;
970 s->current_picture.key_frame= s->pict_type == I_TYPE;
971
972 /* skip everything if we are in a hurry>=5 */
973 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
974 if( (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==B_TYPE)
975 ||(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=I_TYPE)
976 || avctx->skip_frame >= AVDISCARD_ALL)
977 return get_consumed_bytes(s, buf_size);
978
979 if(MPV_frame_start(s, avctx) < 0)
980 return -1;
981
982 ff_er_frame_start(s);
983
984 /* decode each macroblock */
985 s->mb_x=0;
986 s->mb_y=0;
987
988 while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
989 if(ff_h261_resync(h)<0)
990 break;
991 h261_decode_gob(h);
992 }
993 MPV_frame_end(s);
994
995 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
996 assert(s->current_picture.pict_type == s->pict_type);
997 *pict= *(AVFrame*)s->current_picture_ptr;
998 ff_print_debug_info(s, pict);
999
1000 /* Return the Picture timestamp as the frame number */
1001 /* we substract 1 because it is added on utils.c */
1002 avctx->frame_number = s->picture_number - 1;
1003
1004 *data_size = sizeof(AVFrame);
1005
1006 return get_consumed_bytes(s, buf_size);
1007 }
1008
1009 static int h261_decode_end(AVCodecContext *avctx)
1010 {
1011 H261Context *h= avctx->priv_data;
1012 MpegEncContext *s = &h->s;
1013
1014 MPV_common_end(s);
1015 return 0;
1016 }
1017
1018 #ifdef CONFIG_ENCODERS
1019 AVCodec h261_encoder = {
1020 "h261",
1021 CODEC_TYPE_VIDEO,
1022 CODEC_ID_H261,
1023 sizeof(H261Context),
1024 MPV_encode_init,
1025 MPV_encode_picture,
1026 MPV_encode_end,
1027 };
1028 #endif
1029
1030 AVCodec h261_decoder = {
1031 "h261",
1032 CODEC_TYPE_VIDEO,
1033 CODEC_ID_H261,
1034 sizeof(H261Context),
1035 h261_decode_init,
1036 NULL,
1037 h261_decode_end,
1038 h261_decode_frame,
1039 CODEC_CAP_DR1,
1040 };
1041
1042 AVCodecParser h261_parser = {
1043 { CODEC_ID_H261 },
1044 sizeof(ParseContext),
1045 NULL,
1046 h261_parse,
1047 ff_parse_close,
1048 };