3 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2004 Maarten Daniels
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.
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.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
29 #include "mpegvideo.h"
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
39 #define MBA_STUFFING 33
40 #define MBA_STARTCODE 34
41 #define IS_FIL(a) ((a)&MB_TYPE_H261_FIL)
46 typedef struct H261Context{
56 int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
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];
67 if(!(IS_FIL (h->mtype)))
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);
78 static int ff_h261_get_picture_format(int width, int height){
80 if (width == 176 && height == 144)
83 else if (width == 352 && height == 288)
90 static void h261_encode_block(H261Context * h, DCTELEM * block,
92 static int h261_decode_block(H261Context *h, DCTELEM *block,
95 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
96 H261Context * h = (H261Context *) s;
99 align_put_bits(&s->pb);
101 /* Update the pointer to last GOB */
102 s->ptr_lastgob = pbBufPtr(&s->pb);
104 put_bits(&s->pb, 20, 0x10); /* PSC */
106 temp_ref= s->picture_number * (int64_t)30000 * s->avctx->frame_rate_base /
107 (1001 * (int64_t)s->avctx->frame_rate);
108 put_bits(&s->pb, 5, temp_ref & 0x1f); /* TemporalReference */
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 */
114 format = ff_h261_get_picture_format(s->width, s->height);
116 put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
118 put_bits(&s->pb, 1, 0); /* still image mode */
119 put_bits(&s->pb, 1, 0); /* reserved */
121 put_bits(&s->pb, 1, 0); /* no PEI */
130 * Encodes a group of blocks header.
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
138 h->gob_number++; // CIF
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 */
150 void ff_h261_reorder_mb_index(MpegEncContext* s){
151 int index= s->mb_x + s->mb_y*s->mb_width;
154 h261_encode_gob_header(s,0);
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;
164 ff_init_block_index(s);
165 ff_update_block_index(s);
169 static void h261_encode_motion(H261Context * h, int val){
170 MpegEncContext * const s = &h->s;
174 put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][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);
188 static inline int get_cbp(MpegEncContext * s,
189 DCTELEM block[6][64])
193 for (i = 0; i < 6; i++) {
194 if (s->block_last_index[i] >= 0)
199 void ff_h261_encode_mb(MpegEncContext * s,
200 DCTELEM block[6][64],
201 int motion_x, int motion_y)
203 H261Context * h = (H261Context *)s;
204 int mvd, mv_diff_x, mv_diff_y, i, cbp;
205 cbp = 63; // avoid warning
213 cbp= get_cbp(s, block);
215 /* mvd indicates if this block is motion compensated */
216 mvd = motion_x | motion_y;
218 if((cbp | mvd | s->dquant ) == 0) {
219 /* skip macroblock */
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]);
230 /* calculate MTYPE */
234 if(mvd || s->loop_filter)
240 assert(h->mtype > 1);
246 put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
248 h->mtype = h261_mtype_map[h->mtype];
250 if(IS_QUANT(h->mtype)){
251 ff_set_qscale(s,s->qscale+s->dquant);
252 put_bits(&s->pb, 5, s->qscale);
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);
264 h->previous_mba = h->current_mba;
266 if(HAS_CBP(h->mtype)){
267 put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
270 /* encode each block */
271 h261_encode_block(h, block[i], i);
274 if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
280 void ff_h261_encode_init(MpegEncContext *s){
285 init_rl(&h261_rl_tcoeff);
291 s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
296 * encodes a 8x8 block.
297 * @param block the 8x8 block
298 * @param n block index (0-3 are luma, 4-5 are chroma)
300 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
301 MpegEncContext * const s = &h->s;
302 int level, run, last, i, j, last_index, last_non_zero, sign, slevel, code;
305 rl = &h261_rl_tcoeff;
309 /* 255 cannot be represented, so we clamp */
314 /* 0 cannot be represented also */
315 else if (level < 1) {
320 put_bits(&s->pb, 8, 0xff);
322 put_bits(&s->pb, 8, level);
324 } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
326 put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
333 last_index = s->block_last_index[n];
334 last_non_zero = i - 1;
335 for (; i <= last_index; i++) {
336 j = s->intra_scantable.permutated[i];
339 run = i - last_non_zero - 1;
340 last = (i == last_index);
347 code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
348 if(run==0 && level < 16)
350 put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
352 put_bits(&s->pb, 6, run);
354 assert(level <= 127);
355 put_bits(&s->pb, 8, slevel & 0xff);
357 put_bits(&s->pb, 1, sign);
363 put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
367 /***********************************************/
370 static VLC h261_mba_vlc;
371 static VLC h261_mtype_vlc;
372 static VLC h261_mv_vlc;
373 static VLC h261_cbp_vlc;
375 void init_vlc_rl(RLTable *rl);
377 static void h261_decode_init_vlc(H261Context *h){
382 init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
384 h261_mba_code, 1, 1);
385 init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
386 h261_mtype_bits, 1, 1,
387 h261_mtype_code, 1, 1);
388 init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
389 &h261_mv_tab[0][1], 2, 1,
390 &h261_mv_tab[0][0], 2, 1);
391 init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
392 &h261_cbp_tab[0][1], 2, 1,
393 &h261_cbp_tab[0][0], 2, 1);
394 init_rl(&h261_rl_tcoeff);
395 init_vlc_rl(&h261_rl_tcoeff);
399 static int h261_decode_init(AVCodecContext *avctx){
400 H261Context *h= avctx->priv_data;
401 MpegEncContext * const s = &h->s;
404 MPV_decode_defaults(s);
407 s->width = s->avctx->coded_width;
408 s->height = s->avctx->coded_height;
409 s->codec_id = s->avctx->codec->id;
411 s->out_format = FMT_H261;
413 avctx->pix_fmt= PIX_FMT_YUV420P;
415 s->codec_id= avctx->codec->id;
417 h261_decode_init_vlc(h);
419 h->gob_start_code_skipped = 0;
425 * decodes the group of blocks header or slice header.
426 * @return <0 if an error occured
428 static int h261_decode_gob_header(H261Context *h){
430 MpegEncContext * const s = &h->s;
432 if ( !h->gob_start_code_skipped ){
433 /* Check for GOB Start Code */
434 val = show_bits(&s->gb, 15);
439 skip_bits(&s->gb, 16);
442 h->gob_start_code_skipped = 0;
444 h->gob_number = get_bits(&s->gb, 4); /* GN */
445 s->qscale = get_bits(&s->gb, 5); /* GQUANT */
447 /* Check if gob_number is valid */
448 if (s->mb_height==18){ //cif
449 if ((h->gob_number<=0) || (h->gob_number>12))
453 if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
458 while (get_bits1(&s->gb) != 0) {
459 skip_bits(&s->gb, 8);
465 // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
466 // subsequent macroblocks, MBA is the difference between the absolute addresses of
467 // the macroblock and the last transmitted macroblock.
475 * decodes the group of blocks / video packet header.
476 * @return <0 if no resync found
478 static int ff_h261_resync(H261Context *h){
479 MpegEncContext * const s = &h->s;
482 if ( h->gob_start_code_skipped ){
483 ret= h261_decode_gob_header(h);
488 if(show_bits(&s->gb, 15)==0){
489 ret= h261_decode_gob_header(h);
493 //ok, its not where its supposed to be ...
494 s->gb= s->last_resync_gb;
495 align_get_bits(&s->gb);
496 left= s->gb.size_in_bits - get_bits_count(&s->gb);
498 for(;left>15+1+4+5; left-=8){
499 if(show_bits(&s->gb, 15)==0){
500 GetBitContext bak= s->gb;
502 ret= h261_decode_gob_header(h);
508 skip_bits(&s->gb, 8);
516 * decodes skipped macroblocks
519 static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
521 MpegEncContext * const s = &h->s;
526 for(i=mba1; i<mba2; i++){
529 s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
530 s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
531 xy = s->mb_x + s->mb_y * s->mb_stride;
532 ff_init_block_index(s);
533 ff_update_block_index(s);
534 s->dsp.clear_blocks(s->block[0]);
537 s->block_last_index[j] = -1;
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;
545 h->mtype &= ~MB_TYPE_H261_FIL;
547 MPV_decode_mb(s, s->block);
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);
556 /* check if mv_diff is valid */
560 mv_diff = mvmap[mv_diff];
562 if(mv_diff && !get_bits1(gb))
567 else if(v >= 16) v-= 32;
572 static int h261_decode_mb(H261Context *h){
573 MpegEncContext * const s = &h->s;
579 h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
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;
588 while( h->mba_diff == MBA_STUFFING ); // stuffing
590 if ( h->mba_diff < 0 ){
591 if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
594 av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
599 h->current_mba += h->mba_diff;
601 if ( h->current_mba > MBA_STUFFING )
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 s->dsp.clear_blocks(s->block[0]);
612 h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
613 h->mtype = h261_mtype_map[h->mtype];
616 if ( IS_QUANT ( h->mtype ) ){
617 ff_set_qscale(s, get_bits(&s->gb, 5));
620 s->mb_intra = IS_INTRA4x4(h->mtype);
623 if ( IS_16X16 ( h->mtype ) ){
624 // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
625 // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
626 // following three situations:
627 // 1) evaluating MVD for macroblocks 1, 12 and 23;
628 // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
629 // 3) MTYPE of the previous macroblock was not MC.
630 if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
637 h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
638 h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
645 if ( HAS_CBP( h->mtype ) ){
646 cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
650 s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
655 s->mv_dir = MV_DIR_FORWARD;
656 s->mv_type = MV_TYPE_16X16;
657 s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
658 s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
659 s->mv[0][0][1] = h->current_mv_y * 2;
662 /* decode each block */
663 if(s->mb_intra || HAS_CBP(h->mtype)){
664 for (i = 0; i < 6; i++) {
665 if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
672 MPV_decode_mb(s, s->block);
678 * decodes a macroblock
679 * @return <0 if an error occured
681 static int h261_decode_block(H261Context * h, DCTELEM * block,
684 MpegEncContext * const s = &h->s;
685 int code, level, i, j, run;
686 RLTable *rl = &h261_rl_tcoeff;
687 const uint8_t *scan_table;
689 // For the variable length encoding there are two code tables, one being used for
690 // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
691 // for all other LEVELs except the first one in INTRA blocks which is fixed length
692 // coded with 8 bits.
693 // NOTE: the two code tables only differ in one VLC so we handle that manually.
694 scan_table = s->intra_scantable.permutated;
697 level = get_bits(&s->gb, 8);
698 // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
699 if((level&0x7F) == 0){
700 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
703 // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
710 // EOB Not possible for first level when cbp is available (that's why the table is different)
713 int check = show_bits(&s->gb, 2);
716 skip_bits(&s->gb, 2);
717 block[0] = ( check & 0x1 ) ? -1 : 1;
724 s->block_last_index[n] = i - 1;
728 code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
730 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
735 // 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.
736 run = get_bits(&s->gb, 6);
737 level = get_sbits(&s->gb, 8);
741 run = rl->table_run[code];
742 level = rl->table_level[code];
743 if (get_bits1(&s->gb))
748 av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
755 s->block_last_index[n] = i-1;
760 * decodes the H261 picture header.
761 * @return <0 if no startcode found
763 int h261_decode_picture_header(H261Context *h){
764 MpegEncContext * const s = &h->s;
766 uint32_t startcode= 0;
768 for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
769 startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
771 if(startcode == 0x10)
775 if (startcode != 0x10){
776 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
780 /* temporal reference */
781 s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
783 /* PTYPE starts here */
784 skip_bits1(&s->gb); /* split screen off */
785 skip_bits1(&s->gb); /* camera off */
786 skip_bits1(&s->gb); /* freeze picture release off */
788 format = get_bits1(&s->gb);
790 //only 2 formats possible
791 if (format == 0){//QCIF
803 s->mb_num = s->mb_width * s->mb_height;
805 skip_bits1(&s->gb); /* still image mode off */
806 skip_bits1(&s->gb); /* Reserved */
809 while (get_bits1(&s->gb) != 0){
810 skip_bits(&s->gb, 8);
813 // h261 has no I-FRAMES, but if we pass I_TYPE for the first frame, the codec crashes if it does
814 // not contain all I-blocks (e.g. when a packet is lost)
815 s->pict_type = P_TYPE;
821 static int h261_decode_gob(H261Context *h){
822 MpegEncContext * const s = &h->s;
824 ff_set_qscale(s, s->qscale);
827 while(h->current_mba <= MBA_STUFFING)
831 ret= h261_decode_mb(h);
834 h261_decode_mb_skipped(h, h->current_mba, 33);
837 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
841 h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
847 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
851 vop_found= pc->frame_start_found;
856 for(i=0; i<buf_size; i++){
857 state= (state<<8) | buf[i];
859 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
870 for(; i<buf_size; i++){
871 if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
872 state= (state<<8) | buf[i];
874 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
875 pc->frame_start_found=0;
883 pc->frame_start_found= vop_found;
885 return END_NOT_FOUND;
888 static int h261_parse(AVCodecParserContext *s,
889 AVCodecContext *avctx,
890 uint8_t **poutbuf, int *poutbuf_size,
891 const uint8_t *buf, int buf_size)
893 ParseContext *pc = s->priv_data;
896 next= h261_find_frame_end(pc,avctx, buf, buf_size);
897 if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
902 *poutbuf = (uint8_t *)buf;
903 *poutbuf_size = buf_size;
908 * returns the number of bytes consumed for building the current frame
910 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
911 if(s->flags&CODEC_FLAG_TRUNCATED){
912 int pos= (get_bits_count(&s->gb)+7)>>3;
913 pos -= s->parse_context.last_index;
914 if(pos<0) pos=0;// padding is not really read so this might be -1
917 int pos= get_bits_count(&s->gb)>>3;
918 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
919 if(pos+10>buf_size) pos=buf_size; // oops ;)
925 static int h261_decode_frame(AVCodecContext *avctx,
926 void *data, int *data_size,
927 uint8_t *buf, int buf_size)
929 H261Context *h= avctx->priv_data;
930 MpegEncContext *s = &h->s;
932 AVFrame *pict = data;
935 printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
936 printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
938 s->flags= avctx->flags;
939 s->flags2= avctx->flags2;
941 /* no supplementary picture */
946 if(s->flags&CODEC_FLAG_TRUNCATED){
949 next= h261_find_frame_end(&s->parse_context,avctx, buf, buf_size);
951 if( ff_combine_frame(&s->parse_context, next, &buf, &buf_size) < 0 )
958 init_get_bits(&s->gb, buf, buf_size*8);
960 if(!s->context_initialized){
961 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
965 //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
966 if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
967 int i= ff_find_unused_picture(s, 0);
968 s->current_picture_ptr= &s->picture[i];
971 ret = h261_decode_picture_header(h);
973 /* skip if the header was thrashed */
975 av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
979 if (s->width != avctx->coded_width || s->height != avctx->coded_height){
980 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
981 s->parse_context.buffer=0;
983 s->parse_context= pc;
985 if (!s->context_initialized) {
986 avcodec_set_dimensions(avctx, s->width, s->height);
992 s->current_picture.pict_type= s->pict_type;
993 s->current_picture.key_frame= s->pict_type == I_TYPE;
995 /* skip everything if we are in a hurry>=5 */
996 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
998 if(MPV_frame_start(s, avctx) < 0)
1001 ff_er_frame_start(s);
1003 /* decode each macroblock */
1007 while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
1008 if(ff_h261_resync(h)<0)
1014 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
1015 assert(s->current_picture.pict_type == s->pict_type);
1016 *pict= *(AVFrame*)&s->current_picture;
1017 ff_print_debug_info(s, pict);
1019 /* Return the Picture timestamp as the frame number */
1020 /* we substract 1 because it is added on utils.c */
1021 avctx->frame_number = s->picture_number - 1;
1023 *data_size = sizeof(AVFrame);
1025 return get_consumed_bytes(s, buf_size);
1028 static int h261_decode_end(AVCodecContext *avctx)
1030 H261Context *h= avctx->priv_data;
1031 MpegEncContext *s = &h->s;
1037 AVCodec h261_encoder = {
1041 sizeof(H261Context),
1047 AVCodec h261_decoder = {
1051 sizeof(H261Context),
1056 CODEC_CAP_TRUNCATED,
1059 AVCodecParser h261_parser = {
1061 sizeof(ParseContext),