3 * Copyright (c) 2001 Fabrice Bellard.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27 #include "mpegvideo.h"
30 //#define PRINT_FRAME_TIME
31 #ifdef PRINT_FRAME_TIME
32 static inline long long rdtsc()
35 asm volatile( "rdtsc\n\t"
38 // printf("%d\n", int(l/1000));
43 int ff_h263_decode_init(AVCodecContext *avctx)
45 MpegEncContext *s = avctx->priv_data;
48 s->out_format = FMT_H263;
50 s->width = avctx->width;
51 s->height = avctx->height;
52 s->workaround_bugs= avctx->workaround_bugs;
56 s->progressive_sequence=1;
57 s->decode_mb= ff_h263_decode_mb;
59 avctx->pix_fmt= PIX_FMT_YUV420P;
61 /* select sub codec */
62 switch(avctx->codec->id) {
67 s->time_increment_bits = 4; /* default value for broken headers */
69 s->low_delay = 0; //default, might be overriden in the vol header during header parsing
71 case CODEC_ID_MSMPEG4V1:
76 case CODEC_ID_MSMPEG4V2:
81 case CODEC_ID_MSMPEG4V3:
105 s->codec_id= avctx->codec->id;
107 /* for h263, we allocate the images after having read the header */
108 if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
109 if (MPV_common_init(s) < 0)
113 ff_msmpeg4_decode_init(s);
115 h263_decode_init_vlc(s);
120 int ff_h263_decode_end(AVCodecContext *avctx)
122 MpegEncContext *s = avctx->priv_data;
129 * retunrs the number of bytes consumed for building the current frame
131 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
132 int pos= (get_bits_count(&s->gb)+7)>>3;
135 //we would have to scan through the whole buf to handle the weird reordering ...
137 }else if(s->flags&CODEC_FLAG_TRUNCATED){
138 pos -= s->parse_context.last_index;
139 if(pos<0) pos=0; // padding is not really read so this might be -1
142 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
143 if(pos+10>buf_size) pos=buf_size; // oops ;)
149 static int decode_slice(MpegEncContext *s){
150 const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
151 s->last_resync_gb= s->gb;
152 s->first_slice_line= 1;
154 s->resync_mb_x= s->mb_x;
155 s->resync_mb_y= s->mb_y;
157 s->y_dc_scale= s->y_dc_scale_table[ s->qscale ];
158 s->c_dc_scale= s->c_dc_scale_table[ s->qscale ];
160 if(s->partitioned_frame){
161 const int qscale= s->qscale;
163 if(s->codec_id==CODEC_ID_MPEG4){
164 if(ff_mpeg4_decode_partitions(s) < 0)
168 /* restore variables which were modified */
169 s->first_slice_line=1;
170 s->mb_x= s->resync_mb_x;
171 s->mb_y= s->resync_mb_y;
173 s->y_dc_scale= s->y_dc_scale_table[ s->qscale ];
174 s->c_dc_scale= s->c_dc_scale_table[ s->qscale ];
177 for(; s->mb_y < s->mb_height; s->mb_y++) {
178 /* per-row end of slice checks */
179 if(s->msmpeg4_version){
180 if(s->resync_mb_y + s->slice_height == s->mb_y){
181 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, AC_END|DC_END|MV_END);
187 if(s->msmpeg4_version==1){
193 ff_init_block_index(s);
194 for(; s->mb_x < s->mb_width; s->mb_x++) {
197 ff_update_block_index(s);
199 if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
200 s->first_slice_line=0;
204 s->dsp.clear_blocks(s->block[0]);
206 s->mv_dir = MV_DIR_FORWARD;
207 s->mv_type = MV_TYPE_16X16;
209 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
210 ret= s->decode_mb(s, s->block);
212 if (s->pict_type!=B_TYPE)
213 ff_h263_update_motion_val(s);
216 const int xy= s->mb_x + s->mb_y*s->mb_stride;
218 MPV_decode_mb(s, s->block);
220 //printf("%d %d %d %06X\n", s->mb_x, s->mb_y, s->gb.size*8 - get_bits_count(&s->gb), show_bits(&s->gb, 24));
221 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
223 s->padding_bug_score--;
225 if(++s->mb_x >= s->mb_width){
227 ff_draw_horiz_band(s, s->mb_y*16, 16);
231 }else if(ret==SLICE_NOEND){
232 fprintf(stderr,"Slice mismatch at MB: %d\n", xy);
233 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x+1, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
236 fprintf(stderr,"Error at MB: %d\n", xy);
237 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_ERROR|DC_ERROR|MV_ERROR)&part_mask);
242 MPV_decode_mb(s, s->block);
245 ff_draw_horiz_band(s, s->mb_y*16, 16);
250 assert(s->mb_x==0 && s->mb_y==s->mb_height);
252 /* try to detect the padding bug */
253 if( s->codec_id==CODEC_ID_MPEG4
254 && (s->workaround_bugs&FF_BUG_AUTODETECT)
255 && s->gb.size_in_bits - get_bits_count(&s->gb) >=0
256 && s->gb.size_in_bits - get_bits_count(&s->gb) < 48
257 // && !s->resync_marker
258 && !s->data_partitioning){
260 const int bits_count= get_bits_count(&s->gb);
261 const int bits_left = s->gb.size_in_bits - bits_count;
264 s->padding_bug_score+=16;
265 }else if(bits_left>8){
266 s->padding_bug_score++;
267 } else if(bits_left != 1){
268 int v= show_bits(&s->gb, 8);
269 v|= 0x7F >> (7-(bits_count&7));
272 s->padding_bug_score--;
274 s->padding_bug_score++;
278 // handle formats which dont have unique end markers
279 if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
280 int left= s->gb.size_in_bits - get_bits_count(&s->gb);
283 /* no markers in M$ crap */
284 if(s->msmpeg4_version && s->pict_type==I_TYPE)
287 /* buggy padding but the frame should still end approximately at the bitstream end */
288 if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_resilience>=3)
290 else if((s->workaround_bugs&FF_BUG_NO_PADDING))
291 max_extra+= 256*256*256*64;
294 fprintf(stderr, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
297 fprintf(stderr, "overreading %d bits\n", -left);
299 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, AC_END|DC_END|MV_END);
304 fprintf(stderr, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
305 s->gb.size_in_bits - get_bits_count(&s->gb),
306 show_bits(&s->gb, 24), s->padding_bug_score);
308 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
314 * finds the end of the current frame in the bitstream.
315 * @return the position of the first byte of the next frame, or -1
317 static int mpeg4_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
318 ParseContext *pc= &s->parse_context;
322 vop_found= pc->frame_start_found;
327 for(i=0; i<buf_size; i++){
328 state= (state<<8) | buf[i];
338 for(; i<buf_size; i++){
339 state= (state<<8) | buf[i];
340 if((state&0xFFFFFF00) == 0x100){
341 pc->frame_start_found=0;
347 pc->frame_start_found= vop_found;
349 return END_NOT_FOUND;
352 static int h263_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
353 ParseContext *pc= &s->parse_context;
357 vop_found= pc->frame_start_found;
362 for(i=0; i<buf_size; i++){
363 state= (state<<8) | buf[i];
364 if(state>>(32-22) == 0x20){
373 for(; i<buf_size; i++){
374 state= (state<<8) | buf[i];
375 if(state>>(32-22) == 0x20){
376 pc->frame_start_found=0;
382 pc->frame_start_found= vop_found;
385 return END_NOT_FOUND;
388 int ff_h263_decode_frame(AVCodecContext *avctx,
389 void *data, int *data_size,
390 uint8_t *buf, int buf_size)
392 MpegEncContext *s = avctx->priv_data;
394 AVFrame *pict = data;
397 #ifdef PRINT_FRAME_TIME
398 uint64_t time= rdtsc();
401 printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
402 printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
404 s->flags= avctx->flags;
408 /* no supplementary picture */
410 /* special case for last picture */
411 if (s->low_delay==0 && s->next_picture_ptr) {
412 *pict= *(AVFrame*)s->next_picture_ptr;
413 s->next_picture_ptr= NULL;
415 *data_size = sizeof(AVFrame);
421 if(s->flags&CODEC_FLAG_TRUNCATED){
424 if(s->codec_id==CODEC_ID_MPEG4){
425 next= mpeg4_find_frame_end(s, buf, buf_size);
426 }else if(s->codec_id==CODEC_ID_H263){
427 next= h263_find_frame_end(s, buf, buf_size);
429 fprintf(stderr, "this codec doesnt support truncated bitstreams\n");
433 if( ff_combine_frame(s, next, &buf, &buf_size) < 0 )
439 if(s->bitstream_buffer_size && buf_size<20){ //divx 5.01+ frame reorder
440 init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
442 init_get_bits(&s->gb, buf, buf_size*8);
443 s->bitstream_buffer_size=0;
445 if (!s->context_initialized) {
446 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
451 if (s->msmpeg4_version==5) {
452 ret= ff_wmv2_decode_picture_header(s);
453 } else if (s->msmpeg4_version) {
454 ret = msmpeg4_decode_picture_header(s);
455 } else if (s->h263_pred) {
456 if(s->avctx->extradata_size && s->picture_number==0){
459 init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
460 ret = ff_mpeg4_decode_picture_header(s, &gb);
462 ret = ff_mpeg4_decode_picture_header(s, &s->gb);
464 if(s->flags& CODEC_FLAG_LOW_DELAY)
466 } else if (s->h263_intel) {
467 ret = intel_h263_decode_picture_header(s);
468 } else if (s->h263_flv) {
469 ret = flv_h263_decode_picture_header(s);
471 ret = h263_decode_picture_header(s);
474 if(ret==FRAME_SKIPED) return get_consumed_bytes(s, buf_size);
476 /* skip if the header was thrashed */
478 fprintf(stderr, "header damaged\n");
482 avctx->has_b_frames= !s->low_delay;
484 if(s->xvid_build==0 && s->divx_version==0 && s->lavc_build==0){
485 if(s->avctx->stream_codec_tag == ff_get_fourcc("XVID") ||
486 s->avctx->codec_tag == ff_get_fourcc("XVID") || s->avctx->codec_tag == ff_get_fourcc("XVIX"))
489 if(s->avctx->codec_tag == ff_get_fourcc("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
490 && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
495 if(s->xvid_build==0 && s->divx_version==0 && s->lavc_build==0){
496 if(s->avctx->codec_tag == ff_get_fourcc("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
497 s->divx_version= 400; //divx 4
500 if(s->workaround_bugs&FF_BUG_AUTODETECT){
501 s->workaround_bugs &= ~FF_BUG_NO_PADDING;
503 if(s->padding_bug_score > -2 && !s->data_partitioning && (s->divx_version || !s->resync_marker))
504 s->workaround_bugs |= FF_BUG_NO_PADDING;
506 if(s->avctx->codec_tag == ff_get_fourcc("XVIX"))
507 s->workaround_bugs|= FF_BUG_XVID_ILACE;
509 if(s->avctx->codec_tag == ff_get_fourcc("UMP4")){
510 s->workaround_bugs|= FF_BUG_UMP4;
513 if(s->divx_version>=500){
514 s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
517 if(s->divx_version>502){
518 s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
521 if(s->xvid_build && s->xvid_build<=3)
522 s->padding_bug_score= 256*256*256*64;
524 if(s->xvid_build && s->xvid_build<=1)
525 s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
527 if(s->xvid_build && s->xvid_build<=12)
528 s->workaround_bugs|= FF_BUG_EDGE;
530 #define SET_QPEL_FUNC(postfix1, postfix2) \
531 s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
532 s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
533 s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
535 if(s->lavc_build && s->lavc_build<4653)
536 s->workaround_bugs|= FF_BUG_STD_QPEL;
538 if(s->lavc_build && s->lavc_build<4655)
539 s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
541 if(s->lavc_build && s->lavc_build<4670){
542 s->workaround_bugs|= FF_BUG_EDGE;
546 s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
547 //printf("padding_bug_score: %d\n", s->padding_bug_score);
548 if(s->divx_version==501 && s->divx_build==20020416)
549 s->padding_bug_score= 256*256*256*64;
551 if(s->divx_version && s->divx_version<500){
552 s->workaround_bugs|= FF_BUG_EDGE;
556 if(s->divx_version==500)
557 s->padding_bug_score= 256*256*256*64;
559 /* very ugly XVID padding bug detection FIXME/XXX solve this differently
560 * lets hope this at least works
562 if( s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==0
563 && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
564 s->workaround_bugs|= FF_BUG_NO_PADDING;
566 if(s->lavc_build && s->lavc_build<4609) //FIXME not sure about the version num but a 4609 file seems ok
567 s->workaround_bugs|= FF_BUG_NO_PADDING;
571 if(s->workaround_bugs& FF_BUG_STD_QPEL){
572 SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
573 SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
574 SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
575 SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
576 SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
577 SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
579 SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
580 SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
581 SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
582 SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
583 SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
584 SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
587 if(avctx->debug & FF_DEBUG_BUGS)
588 printf("bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
589 s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
590 s->divx_packed ? "p" : "");
592 #if 0 // dump bits per frame / qp / complexity
595 if(!f) f=fopen("rate_qp_cplx.txt", "w");
596 fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
600 /* After H263 & mpeg4 header decode we have the height, width,*/
601 /* and other parameters. So then we could init the picture */
602 /* FIXME: By the way H263 decoder is evolving it should have */
603 /* an H263EncContext */
604 if(s->aspected_height)
605 new_aspect= s->aspected_width*s->width / (float)(s->height*s->aspected_height);
609 if ( s->width != avctx->width || s->height != avctx->height
610 || ABS(new_aspect - avctx->aspect_ratio) > 0.001) {
611 /* H.263 could change picture size any time */
612 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
613 s->parse_context.buffer=0;
615 s->parse_context= pc;
617 if (!s->context_initialized) {
618 avctx->width = s->width;
619 avctx->height = s->height;
620 avctx->aspect_ratio= new_aspect;
625 if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P))
626 s->gob_index = ff_h263_get_gob_height(s);
629 s->current_picture.pict_type= s->pict_type;
630 s->current_picture.key_frame= s->pict_type == I_TYPE;
632 /* skip b frames if we dont have reference frames */
633 if(s->last_picture_ptr==NULL && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
634 /* skip b frames if we are in a hurry */
635 if(avctx->hurry_up && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
636 /* skip everything if we are in a hurry>=5 */
637 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
639 if(s->next_p_frame_damaged){
640 if(s->pict_type==B_TYPE)
641 return get_consumed_bytes(s, buf_size);
643 s->next_p_frame_damaged=0;
646 if(MPV_frame_start(s, avctx) < 0)
650 printf("qscale=%d\n", s->qscale);
653 ff_er_frame_start(s);
655 //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
656 //which isnt available before MPV_frame_start()
657 if (s->msmpeg4_version==5){
658 if(ff_wmv2_decode_secondary_picture_header(s) < 0)
662 /* decode each macroblock */
667 while(s->mb_y<s->mb_height){
668 if(s->msmpeg4_version){
669 if(s->mb_x!=0 || (s->mb_y%s->slice_height)!=0 || get_bits_count(&s->gb) > s->gb.size_in_bits)
672 if(ff_h263_resync(s)<0)
676 if(s->msmpeg4_version<4 && s->h263_pred)
677 ff_mpeg4_clean_buffers(s);
682 if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==I_TYPE)
683 if(msmpeg4_decode_ext_header(s, buf_size) < 0){
684 s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
687 /* divx 5.01+ bistream reorder stuff */
688 if(s->codec_id==CODEC_ID_MPEG4 && s->bitstream_buffer_size==0 && s->divx_packed){
689 int current_pos= get_bits_count(&s->gb)>>3;
691 if( buf_size - current_pos > 5
692 && buf_size - current_pos < BITSTREAM_BUFFER_SIZE){
694 int startcode_found=0;
695 for(i=current_pos; i<buf_size-3; i++){
696 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
702 memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
703 s->bitstream_buffer_size= buf_size - current_pos;
712 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
713 assert(s->current_picture.pict_type == s->pict_type);
714 if(s->pict_type==B_TYPE || s->low_delay){
715 *pict= *(AVFrame*)&s->current_picture;
716 ff_print_debug_info(s, s->current_picture_ptr);
718 *pict= *(AVFrame*)&s->last_picture;
719 ff_print_debug_info(s, s->last_picture_ptr);
722 /* Return the Picture timestamp as the frame number */
723 /* we substract 1 because it is added on utils.c */
724 avctx->frame_number = s->picture_number - 1;
726 /* dont output the last pic after seeking */
727 if(s->last_picture_ptr || s->low_delay)
728 *data_size = sizeof(AVFrame);
729 #ifdef PRINT_FRAME_TIME
730 printf("%Ld\n", rdtsc()-time);
733 return get_consumed_bytes(s, buf_size);
736 static const AVOption mpeg4_decoptions[] =
738 AVOPTION_SUB(avoptions_workaround_bug),
742 AVCodec mpeg4_decoder = {
746 sizeof(MpegEncContext),
750 ff_h263_decode_frame,
751 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED,
752 .options = mpeg4_decoptions,
753 .flush= ff_mpeg_flush,
756 AVCodec h263_decoder = {
760 sizeof(MpegEncContext),
764 ff_h263_decode_frame,
765 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED,
766 .flush= ff_mpeg_flush,
769 AVCodec msmpeg4v1_decoder = {
773 sizeof(MpegEncContext),
777 ff_h263_decode_frame,
778 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
782 AVCodec msmpeg4v2_decoder = {
786 sizeof(MpegEncContext),
790 ff_h263_decode_frame,
791 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
795 AVCodec msmpeg4v3_decoder = {
799 sizeof(MpegEncContext),
803 ff_h263_decode_frame,
804 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
805 .options = mpeg4_decoptions,
808 AVCodec wmv1_decoder = {
812 sizeof(MpegEncContext),
816 ff_h263_decode_frame,
817 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
821 AVCodec h263i_decoder = {
825 sizeof(MpegEncContext),
829 ff_h263_decode_frame,
830 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
834 AVCodec flv_decoder = {
838 sizeof(MpegEncContext),
842 ff_h263_decode_frame,
843 CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1