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 bits_left; //8 - nr of bits left of the following frame in the last byte in this frame
57 int last_bits; //bits left of the following frame in the last byte in this frame
58 int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
61 void ff_h261_loop_filter(MpegEncContext *s){
62 H261Context * h= (H261Context*)s;
63 const int linesize = s->linesize;
64 const int uvlinesize= s->uvlinesize;
65 uint8_t *dest_y = s->dest[0];
66 uint8_t *dest_cb= s->dest[1];
67 uint8_t *dest_cr= s->dest[2];
69 if(!(IS_FIL (h->mtype)))
72 s->dsp.h261_loop_filter(dest_y , linesize);
73 s->dsp.h261_loop_filter(dest_y + 8, linesize);
74 s->dsp.h261_loop_filter(dest_y + 8 * linesize , linesize);
75 s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
76 s->dsp.h261_loop_filter(dest_cb, uvlinesize);
77 s->dsp.h261_loop_filter(dest_cr, uvlinesize);
80 static int ff_h261_get_picture_format(int width, int height){
82 if (width == 176 && height == 144)
85 else if (width == 352 && height == 288)
92 static void h261_encode_block(H261Context * h, DCTELEM * block,
94 static int h261_decode_block(H261Context *h, DCTELEM *block,
97 void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
98 H261Context * h = (H261Context *) s;
101 align_put_bits(&s->pb);
103 /* Update the pointer to last GOB */
104 s->ptr_lastgob = pbBufPtr(&s->pb);
106 put_bits(&s->pb, 20, 0x10); /* PSC */
108 temp_ref= s->picture_number * (int64_t)30000 * s->avctx->frame_rate_base /
109 (1001 * (int64_t)s->avctx->frame_rate);
110 put_bits(&s->pb, 5, temp_ref & 0x1f); /* TemporalReference */
112 put_bits(&s->pb, 1, 0); /* split screen off */
113 put_bits(&s->pb, 1, 0); /* camera off */
114 put_bits(&s->pb, 1, 0); /* freeze picture release off */
116 format = ff_h261_get_picture_format(s->width, s->height);
118 put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
120 put_bits(&s->pb, 1, 0); /* still image mode */
121 put_bits(&s->pb, 1, 0); /* reserved */
123 put_bits(&s->pb, 1, 0); /* no PEI */
132 * Encodes a group of blocks header.
134 static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
135 H261Context * h = (H261Context *)s;
136 if(ff_h261_get_picture_format(s->width, s->height) == 0){
137 h->gob_number+=2; // QCIF
140 h->gob_number++; // CIF
142 put_bits(&s->pb, 16, 1); /* GBSC */
143 put_bits(&s->pb, 4, h->gob_number); /* GN */
144 put_bits(&s->pb, 5, s->qscale); /* GQUANT */
145 put_bits(&s->pb, 1, 0); /* no GEI */
152 void ff_h261_reorder_mb_index(MpegEncContext* s){
153 /* for CIF the GOB's are fragmented in the middle of a scanline
154 that's why we need to adjust the x and y index of the macroblocks */
155 if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
156 if((s->mb_x == 0 && (s->mb_y % 3 == 0) ) || (s->mb_x == 11 && ((s->mb_y -1 )% 3 == 0) ))
157 h261_encode_gob_header(s,0);
159 if((s->mb_y % 3) == 1 ){
163 else if( (s->mb_y % 3) == 2 ){
169 if((s->mb_y % 3) == 1 ){
173 else if( (s->mb_y % 3) == 0 ){
178 ff_init_block_index(s);
179 ff_update_block_index(s);
180 /* for QCIF we don't need to reorder MB's
181 there the GOB's aren't fragmented in the middle of a scanline */
182 }else if(ff_h261_get_picture_format(s->width,s->height) == 0){ // QCIF
183 if(s->mb_y % 3 == 0 && s->mb_x == 0)
184 h261_encode_gob_header(s,0);
188 static void h261_encode_motion(H261Context * h, int val){
189 MpegEncContext * const s = &h->s;
193 put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
201 code = sign ? -val : val;
202 put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
203 put_bits(&s->pb,1,sign);
207 static inline int get_cbp(MpegEncContext * s,
208 DCTELEM block[6][64])
212 for (i = 0; i < 6; i++) {
213 if (s->block_last_index[i] >= 0)
218 void ff_h261_encode_mb(MpegEncContext * s,
219 DCTELEM block[6][64],
220 int motion_x, int motion_y)
222 H261Context * h = (H261Context *)s;
223 int old_mtype, mvd, mv_diff_x, mv_diff_y, i, cbp;
224 cbp = 63; // avoid warning
228 old_mtype = h->mtype;
233 cbp= get_cbp(s, block);
235 /* mvd indicates if this block is motion compensated */
236 if(((motion_x >> 1) - h->current_mv_x != 0) || ((motion_y >> 1 ) - h->current_mv_y) != 0){
239 else if((motion_x >> 1 == 0) && (motion_y >> 1 == 0)){
244 if((cbp | mvd | s->dquant ) == 0) {
245 /* skip macroblock */
253 /* MB is not skipped, encode MBA */
254 put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
256 /* calculate MTYPE */
271 put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
273 h->mtype = h261_mtype_map[h->mtype];
275 if(IS_QUANT(h->mtype)){
276 ff_set_qscale(s,s->qscale+s->dquant);
277 put_bits(&s->pb, 5, s->qscale);
280 if(IS_16X16(h->mtype)){
281 mv_diff_x = (motion_x >> 1) - h->current_mv_x;
282 mv_diff_y = (motion_y >> 1) - h->current_mv_y;
283 h->current_mv_x = (motion_x >> 1);
284 h->current_mv_y = (motion_y >> 1);
285 h261_encode_motion(h,mv_diff_x);
286 h261_encode_motion(h,mv_diff_y);
289 h->previous_mba = h->current_mba;
291 if(HAS_CBP(h->mtype)){
292 put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
295 /* encode each block */
296 h261_encode_block(h, block[i], i);
299 if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
305 void ff_h261_encode_init(MpegEncContext *s){
310 init_rl(&h261_rl_tcoeff);
316 s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
321 * encodes a 8x8 block.
322 * @param block the 8x8 block
323 * @param n block index (0-3 are luma, 4-5 are chroma)
325 static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
326 MpegEncContext * const s = &h->s;
327 int level, run, last, i, j, last_index, last_non_zero, sign, slevel, code;
330 rl = &h261_rl_tcoeff;
334 /* 255 cannot be represented, so we clamp */
339 /* 0 cannot be represented also */
340 else if (level < 1) {
345 put_bits(&s->pb, 8, 0xff);
347 put_bits(&s->pb, 8, level);
349 } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
351 put_bits(&s->pb,1,1);
352 put_bits(&s->pb,1,block[0]>0 ? 0 : 1 );
359 last_index = s->block_last_index[n];
360 last_non_zero = i - 1;
361 for (; i <= last_index; i++) {
362 j = s->intra_scantable.permutated[i];
365 run = i - last_non_zero - 1;
366 last = (i == last_index);
373 code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
374 if(run==0 && level < 16)
376 put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
378 put_bits(&s->pb, 6, run);
383 else if(slevel > 127){
386 put_bits(&s->pb, 8, slevel & 0xff);
388 put_bits(&s->pb, 1, sign);
394 put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
398 /***********************************************/
401 static VLC h261_mba_vlc;
402 static VLC h261_mtype_vlc;
403 static VLC h261_mv_vlc;
404 static VLC h261_cbp_vlc;
406 void init_vlc_rl(RLTable *rl);
408 static void h261_decode_init_vlc(H261Context *h){
413 init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
415 h261_mba_code, 1, 1);
416 init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
417 h261_mtype_bits, 1, 1,
418 h261_mtype_code, 1, 1);
419 init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
420 &h261_mv_tab[0][1], 2, 1,
421 &h261_mv_tab[0][0], 2, 1);
422 init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
423 &h261_cbp_tab[0][1], 2, 1,
424 &h261_cbp_tab[0][0], 2, 1);
425 init_rl(&h261_rl_tcoeff);
426 init_vlc_rl(&h261_rl_tcoeff);
430 static int h261_decode_init(AVCodecContext *avctx){
431 H261Context *h= avctx->priv_data;
432 MpegEncContext * const s = &h->s;
435 MPV_decode_defaults(s);
438 s->width = s->avctx->coded_width;
439 s->height = s->avctx->coded_height;
440 s->codec_id = s->avctx->codec->id;
442 s->out_format = FMT_H261;
444 avctx->pix_fmt= PIX_FMT_YUV420P;
446 s->codec_id= avctx->codec->id;
448 h261_decode_init_vlc(h);
450 h->gob_start_code_skipped = 0;
456 * decodes the group of blocks header or slice header.
457 * @return <0 if an error occured
459 static int h261_decode_gob_header(H261Context *h){
461 MpegEncContext * const s = &h->s;
463 if ( !h->gob_start_code_skipped ){
464 /* Check for GOB Start Code */
465 val = show_bits(&s->gb, 15);
470 skip_bits(&s->gb, 16);
473 h->gob_start_code_skipped = 0;
475 h->gob_number = get_bits(&s->gb, 4); /* GN */
476 s->qscale = get_bits(&s->gb, 5); /* GQUANT */
478 /* Check if gob_number is valid */
479 if (s->mb_height==18){ //cif
480 if ((h->gob_number<=0) || (h->gob_number>12))
484 if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
489 while (get_bits1(&s->gb) != 0) {
490 skip_bits(&s->gb, 8);
496 // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
497 // subsequent macroblocks, MBA is the difference between the absolute addresses of
498 // the macroblock and the last transmitted macroblock.
506 * decodes the group of blocks / video packet header.
507 * @return <0 if no resync found
509 static int ff_h261_resync(H261Context *h){
510 MpegEncContext * const s = &h->s;
513 if ( h->gob_start_code_skipped ){
514 ret= h261_decode_gob_header(h);
519 if(show_bits(&s->gb, 15)==0){
520 ret= h261_decode_gob_header(h);
524 //ok, its not where its supposed to be ...
525 s->gb= s->last_resync_gb;
526 align_get_bits(&s->gb);
527 left= s->gb.size_in_bits - get_bits_count(&s->gb);
529 for(;left>15+1+4+5; left-=8){
530 if(show_bits(&s->gb, 15)==0){
531 GetBitContext bak= s->gb;
533 ret= h261_decode_gob_header(h);
539 skip_bits(&s->gb, 8);
547 * decodes skipped macroblocks
550 static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
552 MpegEncContext * const s = &h->s;
557 for(i=mba1; i<mba2; i++){
560 s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
561 s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
562 xy = s->mb_x + s->mb_y * s->mb_stride;
563 ff_init_block_index(s);
564 ff_update_block_index(s);
565 s->dsp.clear_blocks(s->block[0]);
568 s->block_last_index[j] = -1;
570 s->mv_dir = MV_DIR_FORWARD;
571 s->mv_type = MV_TYPE_16X16;
572 s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
576 h->mtype &= ~MB_TYPE_H261_FIL;
578 MPV_decode_mb(s, s->block);
584 static int decode_mv_component(GetBitContext *gb, int v){
585 int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
587 /* check if mv_diff is valid */
591 mv_diff = mvmap[mv_diff];
593 if(mv_diff && !get_bits1(gb))
598 else if(v >= 16) v-= 32;
603 static int h261_decode_mb(H261Context *h){
604 MpegEncContext * const s = &h->s;
605 int i, cbp, xy, old_mtype;
610 h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
612 /* Check for slice end */
613 /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
614 if (h->mba_diff == MBA_STARTCODE){ // start code
615 h->gob_start_code_skipped = 1;
619 while( h->mba_diff == MBA_STUFFING ); // stuffing
621 if ( h->mba_diff < 0 ){
622 if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
625 av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
630 h->current_mba += h->mba_diff;
632 if ( h->current_mba > MBA_STUFFING )
635 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
636 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
637 xy = s->mb_x + s->mb_y * s->mb_stride;
638 ff_init_block_index(s);
639 ff_update_block_index(s);
640 s->dsp.clear_blocks(s->block[0]);
643 old_mtype = h->mtype;
644 h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
645 h->mtype = h261_mtype_map[h->mtype];
648 if ( IS_QUANT ( h->mtype ) ){
649 ff_set_qscale(s, get_bits(&s->gb, 5));
652 s->mb_intra = IS_INTRA4x4(h->mtype);
655 if ( IS_16X16 ( h->mtype ) ){
656 // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
657 // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
658 // following three situations:
659 // 1) evaluating MVD for macroblocks 1, 12 and 23;
660 // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
661 // 3) MTYPE of the previous macroblock was not MC.
662 if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
663 ( h->mba_diff != 1) || ( !IS_16X16 ( old_mtype ) ))
669 h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
670 h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
674 if ( HAS_CBP( h->mtype ) ){
675 cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
679 s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
684 s->mv_dir = MV_DIR_FORWARD;
685 s->mv_type = MV_TYPE_16X16;
686 s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
687 if(IS_16X16 ( h->mtype )){
688 s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
689 s->mv[0][0][1] = h->current_mv_y * 2;
692 h->current_mv_x = s->mv[0][0][0] = 0;
693 h->current_mv_x = s->mv[0][0][1] = 0;
697 /* decode each block */
698 if(s->mb_intra || HAS_CBP(h->mtype)){
699 for (i = 0; i < 6; i++) {
700 if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
707 MPV_decode_mb(s, s->block);
713 * decodes a macroblock
714 * @return <0 if an error occured
716 static int h261_decode_block(H261Context * h, DCTELEM * block,
719 MpegEncContext * const s = &h->s;
720 int code, level, i, j, run;
721 RLTable *rl = &h261_rl_tcoeff;
722 const uint8_t *scan_table;
724 // For the variable length encoding there are two code tables, one being used for
725 // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
726 // for all other LEVELs except the first one in INTRA blocks which is fixed length
727 // coded with 8 bits.
728 // NOTE: the two code tables only differ in one VLC so we handle that manually.
729 scan_table = s->intra_scantable.permutated;
732 level = get_bits(&s->gb, 8);
733 // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
734 if((level&0x7F) == 0){
735 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
738 // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
745 // EOB Not possible for first level when cbp is available (that's why the table is different)
748 int check = show_bits(&s->gb, 2);
751 skip_bits(&s->gb, 2);
752 block[0] = ( check & 0x1 ) ? -1 : 1;
759 s->block_last_index[n] = i - 1;
763 code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
765 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
770 // 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.
771 run = get_bits(&s->gb, 6);
772 level = (int8_t)get_bits(&s->gb, 8);
776 run = rl->table_run[code];
777 level = rl->table_level[code];
778 if (get_bits1(&s->gb))
783 av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
790 s->block_last_index[n] = i-1;
795 * decodes the H261 picture header.
796 * @return <0 if no startcode found
798 int h261_decode_picture_header(H261Context *h){
799 MpegEncContext * const s = &h->s;
801 uint32_t startcode= 0;
803 for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
804 startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
806 if(startcode == 0x10)
810 if (startcode != 0x10){
811 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
815 /* temporal reference */
816 s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
818 /* PTYPE starts here */
819 skip_bits1(&s->gb); /* split screen off */
820 skip_bits1(&s->gb); /* camera off */
821 skip_bits1(&s->gb); /* freeze picture release off */
823 format = get_bits1(&s->gb);
825 //only 2 formats possible
826 if (format == 0){//QCIF
838 s->mb_num = s->mb_width * s->mb_height;
840 skip_bits1(&s->gb); /* still image mode off */
841 skip_bits1(&s->gb); /* Reserved */
844 while (get_bits1(&s->gb) != 0){
845 skip_bits(&s->gb, 8);
848 // h261 has no I-FRAMES, but if we pass I_TYPE for the first frame, the codec crashes if it does
849 // not contain all I-blocks (e.g. when a packet is lost)
850 s->pict_type = P_TYPE;
856 static int h261_decode_gob(H261Context *h){
857 MpegEncContext * const s = &h->s;
859 ff_set_qscale(s, s->qscale);
862 while(h->current_mba <= MBA_STUFFING)
866 ret= h261_decode_mb(h);
869 h261_decode_mb_skipped(h, h->current_mba, 33);
872 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
876 h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
882 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
883 int vop_found, i, j, bits_left, last_bits;
886 H261Context *h = avctx->priv_data;
889 bits_left = h->bits_left;
890 last_bits = h->last_bits;
897 vop_found= pc->frame_start_found;
899 if(bits_left!=0 && !vop_found)
900 state = state << (8-bits_left) | last_bits;
903 for(i=0; i<buf_size; i++){
904 state= (state<<8) | buf[i];
906 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
917 for(; i<buf_size; i++){
918 if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
919 state= (state<<8) | buf[i];
921 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
922 pc->frame_start_found=0;
930 pc->frame_start_found= vop_found;
932 return END_NOT_FOUND;
935 static int h261_parse(AVCodecParserContext *s,
936 AVCodecContext *avctx,
937 uint8_t **poutbuf, int *poutbuf_size,
938 const uint8_t *buf, int buf_size)
940 ParseContext *pc = s->priv_data;
943 next= h261_find_frame_end(pc,avctx, buf, buf_size);
944 if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
949 *poutbuf = (uint8_t *)buf;
950 *poutbuf_size = buf_size;
955 * returns the number of bytes consumed for building the current frame
957 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
958 if(s->flags&CODEC_FLAG_TRUNCATED){
959 int pos= (get_bits_count(&s->gb)+7)>>3;
960 pos -= s->parse_context.last_index;
961 if(pos<0) pos=0;// padding is not really read so this might be -1
964 int pos= get_bits_count(&s->gb)>>3;
965 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
966 if(pos+10>buf_size) pos=buf_size; // oops ;)
972 static int h261_decode_frame(AVCodecContext *avctx,
973 void *data, int *data_size,
974 uint8_t *buf, int buf_size)
976 H261Context *h= avctx->priv_data;
977 MpegEncContext *s = &h->s;
979 AVFrame *pict = data;
982 printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
983 printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
985 s->flags= avctx->flags;
986 s->flags2= avctx->flags2;
988 /* no supplementary picture */
993 if(s->flags&CODEC_FLAG_TRUNCATED){
996 next= h261_find_frame_end(&s->parse_context,avctx, buf, buf_size);
998 if( ff_combine_frame(&s->parse_context, next, &buf, &buf_size) < 0 )
1005 init_get_bits(&s->gb, buf, buf_size*8);
1007 if(!s->context_initialized){
1008 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
1012 //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
1013 if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
1014 int i= ff_find_unused_picture(s, 0);
1015 s->current_picture_ptr= &s->picture[i];
1018 ret = h261_decode_picture_header(h);
1020 /* skip if the header was thrashed */
1022 av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
1026 if (s->width != avctx->coded_width || s->height != avctx->coded_height){
1027 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
1028 s->parse_context.buffer=0;
1030 s->parse_context= pc;
1032 if (!s->context_initialized) {
1033 avcodec_set_dimensions(avctx, s->width, s->height);
1039 s->current_picture.pict_type= s->pict_type;
1040 s->current_picture.key_frame= s->pict_type == I_TYPE;
1042 /* skip everything if we are in a hurry>=5 */
1043 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
1045 if(MPV_frame_start(s, avctx) < 0)
1048 ff_er_frame_start(s);
1050 /* decode each macroblock */
1054 while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
1055 if(ff_h261_resync(h)<0)
1061 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
1062 assert(s->current_picture.pict_type == s->pict_type);
1063 *pict= *(AVFrame*)&s->current_picture;
1064 ff_print_debug_info(s, pict);
1066 /* Return the Picture timestamp as the frame number */
1067 /* we substract 1 because it is added on utils.c */
1068 avctx->frame_number = s->picture_number - 1;
1070 *data_size = sizeof(AVFrame);
1072 return get_consumed_bytes(s, buf_size);
1075 static int h261_decode_end(AVCodecContext *avctx)
1077 H261Context *h= avctx->priv_data;
1078 MpegEncContext *s = &h->s;
1084 AVCodec h261_encoder = {
1088 sizeof(H261Context),
1094 AVCodec h261_decoder = {
1098 sizeof(H261Context),
1103 CODEC_CAP_TRUNCATED,
1106 AVCodecParser h261_parser = {
1108 sizeof(ParseContext),