libavcodec/h264_refs.c

   1 /*
   2  * H.26L/H.264/AVC/JVT/14496-10/... reference picture handling
   3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * H.264 / AVC / MPEG4 part10  reference picture handling.
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #include "internal.h"
  29 #include "dsputil.h"
  30 #include "avcodec.h"
  31 #include "h264.h"
  32 #include "golomb.h"
  33
  34 //#undef NDEBUG
  35 #include <assert.h>
  36
  37
  38 static void pic_as_field(Picture *pic, const int parity){
  39     int i;
  40     for (i = 0; i < 4; ++i) {
  41         if (parity == PICT_BOTTOM_FIELD)
  42             pic->data[i] += pic->linesize[i];
  43         pic->reference = parity;
  44         pic->linesize[i] *= 2;
  45     }
  46     pic->poc= pic->field_poc[parity == PICT_BOTTOM_FIELD];
  47 }
  48
  49 static int split_field_copy(Picture *dest, Picture *src,
  50                             int parity, int id_add){
  51     int match = !!(src->reference & parity);
  52
  53     if (match) {
  54         *dest = *src;
  55         if(parity != PICT_FRAME){
  56             pic_as_field(dest, parity);
  57             dest->pic_id *= 2;
  58             dest->pic_id += id_add;
  59         }
  60     }
  61
  62     return match;
  63 }
  64
  65 static int build_def_list(Picture *def, Picture **in, int len, int is_long, int sel){
  66     int i[2]={0};
  67     int index=0;
  68
  69     while(i[0]<len || i[1]<len){
  70         while(i[0]<len && !(in[ i[0] ] && (in[ i[0] ]->reference & sel)))
  71             i[0]++;
  72         while(i[1]<len && !(in[ i[1] ] && (in[ i[1] ]->reference & (sel^3))))
  73             i[1]++;
  74         if(i[0] < len){
  75             in[ i[0] ]->pic_id= is_long ? i[0] : in[ i[0] ]->frame_num;
  76             split_field_copy(&def[index++], in[ i[0]++ ], sel  , 1);
  77         }
  78         if(i[1] < len){
  79             in[ i[1] ]->pic_id= is_long ? i[1] : in[ i[1] ]->frame_num;
  80             split_field_copy(&def[index++], in[ i[1]++ ], sel^3, 0);
  81         }
  82     }
  83
  84     return index;
  85 }
  86
  87 static int add_sorted(Picture **sorted, Picture **src, int len, int limit, int dir){
  88     int i, best_poc;
  89     int out_i= 0;
  90
  91     for(;;){
  92         best_poc= dir ? INT_MIN : INT_MAX;
  93
  94         for(i=0; i<len; i++){
  95             const int poc= src[i]->poc;
  96             if(((poc > limit) ^ dir) && ((poc < best_poc) ^ dir)){
  97                 best_poc= poc;
  98                 sorted[out_i]= src[i];
  99             }
 100         }
 101         if(best_poc == (dir ? INT_MIN : INT_MAX))
 102             break;
 103         limit= sorted[out_i++]->poc - dir;
 104     }
 105     return out_i;
 106 }
 107
 108 int ff_h264_fill_default_ref_list(H264Context *h){
 109     MpegEncContext * const s = &h->s;
 110     int i, len;
 111
 112     if(h->slice_type_nos==FF_B_TYPE){
 113         Picture *sorted[32];
 114         int cur_poc, list;
 115         int lens[2];
 116
 117         if(FIELD_PICTURE)
 118             cur_poc= s->current_picture_ptr->field_poc[ s->picture_structure == PICT_BOTTOM_FIELD ];
 119         else
 120             cur_poc= s->current_picture_ptr->poc;
 121
 122         for(list= 0; list<2; list++){
 123             len= add_sorted(sorted    , h->short_ref, h->short_ref_count, cur_poc, 1^list);
 124             len+=add_sorted(sorted+len, h->short_ref, h->short_ref_count, cur_poc, 0^list);
 125             assert(len<=32);
 126             len= build_def_list(h->default_ref_list[list]    , sorted     , len, 0, s->picture_structure);
 127             len+=build_def_list(h->default_ref_list[list]+len, h->long_ref, 16 , 1, s->picture_structure);
 128             assert(len<=32);
 129
 130             if(len < h->ref_count[list])
 131                 memset(&h->default_ref_list[list][len], 0, sizeof(Picture)*(h->ref_count[list] - len));
 132             lens[list]= len;
 133         }
 134
 135         if(lens[0] == lens[1] && lens[1] > 1){
 136             for(i=0; h->default_ref_list[0][i].data[0] == h->default_ref_list[1][i].data[0] && i<lens[0]; i++);
 137             if(i == lens[0])
 138                 FFSWAP(Picture, h->default_ref_list[1][0], h->default_ref_list[1][1]);
 139         }
 140     }else{
 141         len = build_def_list(h->default_ref_list[0]    , h->short_ref, h->short_ref_count, 0, s->picture_structure);
 142         len+= build_def_list(h->default_ref_list[0]+len, h-> long_ref, 16                , 1, s->picture_structure);
 143         assert(len <= 32);
 144         if(len < h->ref_count[0])
 145             memset(&h->default_ref_list[0][len], 0, sizeof(Picture)*(h->ref_count[0] - len));
 146     }
 147 #ifdef TRACE
 148     for (i=0; i<h->ref_count[0]; i++) {
 149         tprintf(h->s.avctx, "List0: %s fn:%d 0x%p\n", (h->default_ref_list[0][i].long_ref ? "LT" : "ST"), h->default_ref_list[0][i].pic_id, h->default_ref_list[0][i].data[0]);
 150     }
 151     if(h->slice_type_nos==FF_B_TYPE){
 152         for (i=0; i<h->ref_count[1]; i++) {
 153             tprintf(h->s.avctx, "List1: %s fn:%d 0x%p\n", (h->default_ref_list[1][i].long_ref ? "LT" : "ST"), h->default_ref_list[1][i].pic_id, h->default_ref_list[1][i].data[0]);
 154         }
 155     }
 156 #endif
 157     return 0;
 158 }
 159
 160 static void print_short_term(H264Context *h);
 161 static void print_long_term(H264Context *h);
 162
 163 /**
 164  * Extract structure information about the picture described by pic_num in
 165  * the current decoding context (frame or field). Note that pic_num is
 166  * picture number without wrapping (so, 0<=pic_num<max_pic_num).
 167  * @param pic_num picture number for which to extract structure information
 168  * @param structure one of PICT_XXX describing structure of picture
 169  *                      with pic_num
 170  * @return frame number (short term) or long term index of picture
 171  *         described by pic_num
 172  */
 173 static int pic_num_extract(H264Context *h, int pic_num, int *structure){
 174     MpegEncContext * const s = &h->s;
 175
 176     *structure = s->picture_structure;
 177     if(FIELD_PICTURE){
 178         if (!(pic_num & 1))
 179             /* opposite field */
 180             *structure ^= PICT_FRAME;
 181         pic_num >>= 1;
 182     }
 183
 184     return pic_num;
 185 }
 186
 187 int ff_h264_decode_ref_pic_list_reordering(H264Context *h){
 188     MpegEncContext * const s = &h->s;
 189     int list, index, pic_structure;
 190
 191     print_short_term(h);
 192     print_long_term(h);
 193
 194     for(list=0; list<h->list_count; list++){
 195         memcpy(h->ref_list[list], h->default_ref_list[list], sizeof(Picture)*h->ref_count[list]);
 196
 197         if(get_bits1(&s->gb)){
 198             int pred= h->curr_pic_num;
 199
 200             for(index=0; ; index++){
 201                 unsigned int reordering_of_pic_nums_idc= get_ue_golomb_31(&s->gb);
 202                 unsigned int pic_id;
 203                 int i;
 204                 Picture *ref = NULL;
 205
 206                 if(reordering_of_pic_nums_idc==3)
 207                     break;
 208
 209                 if(index >= h->ref_count[list]){
 210                     av_log(h->s.avctx, AV_LOG_ERROR, "reference count overflow\n");
 211                     return -1;
 212                 }
 213
 214                 if(reordering_of_pic_nums_idc<3){
 215                     if(reordering_of_pic_nums_idc<2){
 216                         const unsigned int abs_diff_pic_num= get_ue_golomb(&s->gb) + 1;
 217                         int frame_num;
 218
 219                         if(abs_diff_pic_num > h->max_pic_num){
 220                             av_log(h->s.avctx, AV_LOG_ERROR, "abs_diff_pic_num overflow\n");
 221                             return -1;
 222                         }
 223
 224                         if(reordering_of_pic_nums_idc == 0) pred-= abs_diff_pic_num;
 225                         else                                pred+= abs_diff_pic_num;
 226                         pred &= h->max_pic_num - 1;
 227
 228                         frame_num = pic_num_extract(h, pred, &pic_structure);
 229
 230                         for(i= h->short_ref_count-1; i>=0; i--){
 231                             ref = h->short_ref[i];
 232                             assert(ref->reference);
 233                             assert(!ref->long_ref);
 234                             if(
 235                                    ref->frame_num == frame_num &&
 236                                    (ref->reference & pic_structure)
 237                               )
 238                                 break;
 239                         }
 240                         if(i>=0)
 241                             ref->pic_id= pred;
 242                     }else{
 243                         int long_idx;
 244                         pic_id= get_ue_golomb(&s->gb); //long_term_pic_idx
 245
 246                         long_idx= pic_num_extract(h, pic_id, &pic_structure);
 247
 248                         if(long_idx>31){
 249                             av_log(h->s.avctx, AV_LOG_ERROR, "long_term_pic_idx overflow\n");
 250                             return -1;
 251                         }
 252                         ref = h->long_ref[long_idx];
 253                         assert(!(ref && !ref->reference));
 254                         if(ref && (ref->reference & pic_structure)){
 255                             ref->pic_id= pic_id;
 256                             assert(ref->long_ref);
 257                             i=0;
 258                         }else{
 259                             i=-1;
 260                         }
 261                     }
 262
 263                     if (i < 0) {
 264                         av_log(h->s.avctx, AV_LOG_ERROR, "reference picture missing during reorder\n");
 265                         memset(&h->ref_list[list][index], 0, sizeof(Picture)); //FIXME
 266                     } else {
 267                         for(i=index; i+1<h->ref_count[list]; i++){
 268                             if(ref->long_ref == h->ref_list[list][i].long_ref && ref->pic_id == h->ref_list[list][i].pic_id)
 269                                 break;
 270                         }
 271                         for(; i > index; i--){
 272                             h->ref_list[list][i]= h->ref_list[list][i-1];
 273                         }
 274                         h->ref_list[list][index]= *ref;
 275                         if (FIELD_PICTURE){
 276                             pic_as_field(&h->ref_list[list][index], pic_structure);
 277                         }
 278                     }
 279                 }else{
 280                     av_log(h->s.avctx, AV_LOG_ERROR, "illegal reordering_of_pic_nums_idc\n");
 281                     return -1;
 282                 }
 283             }
 284         }
 285     }
 286     for(list=0; list<h->list_count; list++){
 287         for(index= 0; index < h->ref_count[list]; index++){
 288             if(!h->ref_list[list][index].data[0]){
 289                 av_log(h->s.avctx, AV_LOG_ERROR, "Missing reference picture\n");
 290                 if(h->default_ref_list[list][0].data[0])
 291                     h->ref_list[list][index]= h->default_ref_list[list][0];
 292                 else
 293                     return -1;
 294             }
 295         }
 296     }
 297
 298     return 0;
 299 }
 300
 301 void ff_h264_fill_mbaff_ref_list(H264Context *h){
 302     int list, i, j;
 303     for(list=0; list<2; list++){ //FIXME try list_count
 304         for(i=0; i<h->ref_count[list]; i++){
 305             Picture *frame = &h->ref_list[list][i];
 306             Picture *field = &h->ref_list[list][16+2*i];
 307             field[0] = *frame;
 308             for(j=0; j<3; j++)
 309                 field[0].linesize[j] <<= 1;
 310             field[0].reference = PICT_TOP_FIELD;
 311             field[0].poc= field[0].field_poc[0];
 312             field[1] = field[0];
 313             for(j=0; j<3; j++)
 314                 field[1].data[j] += frame->linesize[j];
 315             field[1].reference = PICT_BOTTOM_FIELD;
 316             field[1].poc= field[1].field_poc[1];
 317
 318             h->luma_weight[16+2*i][list][0] = h->luma_weight[16+2*i+1][list][0] = h->luma_weight[i][list][0];
 319             h->luma_weight[16+2*i][list][1] = h->luma_weight[16+2*i+1][list][1] = h->luma_weight[i][list][1];
 320             for(j=0; j<2; j++){
 321                 h->chroma_weight[16+2*i][list][j][0] = h->chroma_weight[16+2*i+1][list][j][0] = h->chroma_weight[i][list][j][0];
 322                 h->chroma_weight[16+2*i][list][j][1] = h->chroma_weight[16+2*i+1][list][j][1] = h->chroma_weight[i][list][j][1];
 323             }
 324         }
 325     }
 326 }
 327
 328 /**
 329  * Mark a picture as no longer needed for reference. The refmask
 330  * argument allows unreferencing of individual fields or the whole frame.
 331  * If the picture becomes entirely unreferenced, but is being held for
 332  * display purposes, it is marked as such.
 333  * @param refmask mask of fields to unreference; the mask is bitwise
 334  *                anded with the reference marking of pic
 335  * @return non-zero if pic becomes entirely unreferenced (except possibly
 336  *         for display purposes) zero if one of the fields remains in
 337  *         reference
 338  */
 339 static inline int unreference_pic(H264Context *h, Picture *pic, int refmask){
 340     int i;
 341     if (pic->reference &= refmask) {
 342         return 0;
 343     } else {
 344         for(i = 0; h->delayed_pic[i]; i++)
 345             if(pic == h->delayed_pic[i]){
 346                 pic->reference=DELAYED_PIC_REF;
 347                 break;
 348             }
 349         return 1;
 350     }
 351 }
 352
 353 /**
 354  * Find a Picture in the short term reference list by frame number.
 355  * @param frame_num frame number to search for
 356  * @param idx the index into h->short_ref where returned picture is found
 357  *            undefined if no picture found.
 358  * @return pointer to the found picture, or NULL if no pic with the provided
 359  *                 frame number is found
 360  */
 361 static Picture * find_short(H264Context *h, int frame_num, int *idx){
 362     MpegEncContext * const s = &h->s;
 363     int i;
 364
 365     for(i=0; i<h->short_ref_count; i++){
 366         Picture *pic= h->short_ref[i];
 367         if(s->avctx->debug&FF_DEBUG_MMCO)
 368             av_log(h->s.avctx, AV_LOG_DEBUG, "%d %d %p\n", i, pic->frame_num, pic);
 369         if(pic->frame_num == frame_num) {
 370             *idx = i;
 371             return pic;
 372         }
 373     }
 374     return NULL;
 375 }
 376
 377 /**
 378  * Remove a picture from the short term reference list by its index in
 379  * that list.  This does no checking on the provided index; it is assumed
 380  * to be valid. Other list entries are shifted down.
 381  * @param i index into h->short_ref of picture to remove.
 382  */
 383 static void remove_short_at_index(H264Context *h, int i){
 384     assert(i >= 0 && i < h->short_ref_count);
 385     h->short_ref[i]= NULL;
 386     if (--h->short_ref_count)
 387         memmove(&h->short_ref[i], &h->short_ref[i+1], (h->short_ref_count - i)*sizeof(Picture*));
 388 }
 389
 390 /**
 391  *
 392  * @return the removed picture or NULL if an error occurs
 393  */
 394 static Picture * remove_short(H264Context *h, int frame_num, int ref_mask){
 395     MpegEncContext * const s = &h->s;
 396     Picture *pic;
 397     int i;
 398
 399     if(s->avctx->debug&FF_DEBUG_MMCO)
 400         av_log(h->s.avctx, AV_LOG_DEBUG, "remove short %d count %d\n", frame_num, h->short_ref_count);
 401
 402     pic = find_short(h, frame_num, &i);
 403     if (pic){
 404         if(unreference_pic(h, pic, ref_mask))
 405         remove_short_at_index(h, i);
 406     }
 407
 408     return pic;
 409 }
 410
 411 /**
 412  * Remove a picture from the long term reference list by its index in
 413  * that list.
 414  * @return the removed picture or NULL if an error occurs
 415  */
 416 static Picture * remove_long(H264Context *h, int i, int ref_mask){
 417     Picture *pic;
 418
 419     pic= h->long_ref[i];
 420     if (pic){
 421         if(unreference_pic(h, pic, ref_mask)){
 422             assert(h->long_ref[i]->long_ref == 1);
 423             h->long_ref[i]->long_ref= 0;
 424             h->long_ref[i]= NULL;
 425             h->long_ref_count--;
 426         }
 427     }
 428
 429     return pic;
 430 }
 431
 432 void ff_h264_remove_all_refs(H264Context *h){
 433     int i;
 434
 435     for(i=0; i<16; i++){
 436         remove_long(h, i, 0);
 437     }
 438     assert(h->long_ref_count==0);
 439
 440     for(i=0; i<h->short_ref_count; i++){
 441         unreference_pic(h, h->short_ref[i], 0);
 442         h->short_ref[i]= NULL;
 443     }
 444     h->short_ref_count=0;
 445 }
 446
 447 /**
 448  * print short term list
 449  */
 450 static void print_short_term(H264Context *h) {
 451     uint32_t i;
 452     if(h->s.avctx->debug&FF_DEBUG_MMCO) {
 453         av_log(h->s.avctx, AV_LOG_DEBUG, "short term list:\n");
 454         for(i=0; i<h->short_ref_count; i++){
 455             Picture *pic= h->short_ref[i];
 456             av_log(h->s.avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->data[0]);
 457         }
 458     }
 459 }
 460
 461 /**
 462  * print long term list
 463  */
 464 static void print_long_term(H264Context *h) {
 465     uint32_t i;
 466     if(h->s.avctx->debug&FF_DEBUG_MMCO) {
 467         av_log(h->s.avctx, AV_LOG_DEBUG, "long term list:\n");
 468         for(i = 0; i < 16; i++){
 469             Picture *pic= h->long_ref[i];
 470             if (pic) {
 471                 av_log(h->s.avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->data[0]);
 472             }
 473         }
 474     }
 475 }
 476
 477 int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count){
 478     MpegEncContext * const s = &h->s;
 479     int i, av_uninit(j);
 480     int current_ref_assigned=0;
 481     Picture *av_uninit(pic);
 482
 483     if((s->avctx->debug&FF_DEBUG_MMCO) && mmco_count==0)
 484         av_log(h->s.avctx, AV_LOG_DEBUG, "no mmco here\n");
 485
 486     for(i=0; i<mmco_count; i++){
 487         int av_uninit(structure), av_uninit(frame_num);
 488         if(s->avctx->debug&FF_DEBUG_MMCO)
 489             av_log(h->s.avctx, AV_LOG_DEBUG, "mmco:%d %d %d\n", h->mmco[i].opcode, h->mmco[i].short_pic_num, h->mmco[i].long_arg);
 490
 491         if(   mmco[i].opcode == MMCO_SHORT2UNUSED
 492            || mmco[i].opcode == MMCO_SHORT2LONG){
 493             frame_num = pic_num_extract(h, mmco[i].short_pic_num, &structure);
 494             pic = find_short(h, frame_num, &j);
 495             if(!pic){
 496                 if(mmco[i].opcode != MMCO_SHORT2LONG || !h->long_ref[mmco[i].long_arg]
 497                    || h->long_ref[mmco[i].long_arg]->frame_num != frame_num)
 498                 av_log(h->s.avctx, AV_LOG_ERROR, "mmco: unref short failure\n");
 499                 continue;
 500             }
 501         }
 502
 503         switch(mmco[i].opcode){
 504         case MMCO_SHORT2UNUSED:
 505             if(s->avctx->debug&FF_DEBUG_MMCO)
 506                 av_log(h->s.avctx, AV_LOG_DEBUG, "mmco: unref short %d count %d\n", h->mmco[i].short_pic_num, h->short_ref_count);
 507             remove_short(h, frame_num, structure ^ PICT_FRAME);
 508             break;
 509         case MMCO_SHORT2LONG:
 510                 if (h->long_ref[mmco[i].long_arg] != pic)
 511                     remove_long(h, mmco[i].long_arg, 0);
 512
 513                 remove_short_at_index(h, j);
 514                 h->long_ref[ mmco[i].long_arg ]= pic;
 515                 if (h->long_ref[ mmco[i].long_arg ]){
 516                     h->long_ref[ mmco[i].long_arg ]->long_ref=1;
 517                     h->long_ref_count++;
 518                 }
 519             break;
 520         case MMCO_LONG2UNUSED:
 521             j = pic_num_extract(h, mmco[i].long_arg, &structure);
 522             pic = h->long_ref[j];
 523             if (pic) {
 524                 remove_long(h, j, structure ^ PICT_FRAME);
 525             } else if(s->avctx->debug&FF_DEBUG_MMCO)
 526                 av_log(h->s.avctx, AV_LOG_DEBUG, "mmco: unref long failure\n");
 527             break;
 528         case MMCO_LONG:
 529                     // Comment below left from previous code as it is an interresting note.
 530                     /* First field in pair is in short term list or
 531                      * at a different long term index.
 532                      * This is not allowed; see 7.4.3.3, notes 2 and 3.
 533                      * Report the problem and keep the pair where it is,
 534                      * and mark this field valid.
 535                      */
 536
 537             if (h->long_ref[mmco[i].long_arg] != s->current_picture_ptr) {
 538                 remove_long(h, mmco[i].long_arg, 0);
 539
 540                 h->long_ref[ mmco[i].long_arg ]= s->current_picture_ptr;
 541                 h->long_ref[ mmco[i].long_arg ]->long_ref=1;
 542                 h->long_ref_count++;
 543             }
 544
 545             s->current_picture_ptr->reference |= s->picture_structure;
 546             current_ref_assigned=1;
 547             break;
 548         case MMCO_SET_MAX_LONG:
 549             assert(mmco[i].long_arg <= 16);
 550             // just remove the long term which index is greater than new max
 551             for(j = mmco[i].long_arg; j<16; j++){
 552                 remove_long(h, j, 0);
 553             }
 554             break;
 555         case MMCO_RESET:
 556             while(h->short_ref_count){
 557                 remove_short(h, h->short_ref[0]->frame_num, 0);
 558             }
 559             for(j = 0; j < 16; j++) {
 560                 remove_long(h, j, 0);
 561             }
 562             s->current_picture_ptr->poc=
 563             s->current_picture_ptr->field_poc[0]=
 564             s->current_picture_ptr->field_poc[1]=
 565             h->poc_lsb=
 566             h->poc_msb=
 567             h->frame_num=
 568             s->current_picture_ptr->frame_num= 0;
 569             s->current_picture_ptr->mmco_reset=1;
 570             break;
 571         default: assert(0);
 572         }
 573     }
 574
 575     if (!current_ref_assigned) {
 576         /* Second field of complementary field pair; the first field of
 577          * which is already referenced. If short referenced, it
 578          * should be first entry in short_ref. If not, it must exist
 579          * in long_ref; trying to put it on the short list here is an
 580          * error in the encoded bit stream (ref: 7.4.3.3, NOTE 2 and 3).
 581          */
 582         if (h->short_ref_count && h->short_ref[0] == s->current_picture_ptr) {
 583             /* Just mark the second field valid */
 584             s->current_picture_ptr->reference = PICT_FRAME;
 585         } else if (s->current_picture_ptr->long_ref) {
 586             av_log(h->s.avctx, AV_LOG_ERROR, "illegal short term reference "
 587                                              "assignment for second field "
 588                                              "in complementary field pair "
 589                                              "(first field is long term)\n");
 590         } else {
 591             pic= remove_short(h, s->current_picture_ptr->frame_num, 0);
 592             if(pic){
 593                 av_log(h->s.avctx, AV_LOG_ERROR, "illegal short term buffer state detected\n");
 594             }
 595
 596             if(h->short_ref_count)
 597                 memmove(&h->short_ref[1], &h->short_ref[0], h->short_ref_count*sizeof(Picture*));
 598
 599             h->short_ref[0]= s->current_picture_ptr;
 600             h->short_ref_count++;
 601             s->current_picture_ptr->reference |= s->picture_structure;
 602         }
 603     }
 604
 605     if (h->long_ref_count + h->short_ref_count > h->sps.ref_frame_count){
 606
 607         /* We have too many reference frames, probably due to corrupted
 608          * stream. Need to discard one frame. Prevents overrun of the
 609          * short_ref and long_ref buffers.
 610          */
 611         av_log(h->s.avctx, AV_LOG_ERROR,
 612                "number of reference frames exceeds max (probably "
 613                "corrupt input), discarding one\n");
 614
 615         if (h->long_ref_count && !h->short_ref_count) {
 616             for (i = 0; i < 16; ++i)
 617                 if (h->long_ref[i])
 618                     break;
 619
 620             assert(i < 16);
 621             remove_long(h, i, 0);
 622         } else {
 623             pic = h->short_ref[h->short_ref_count - 1];
 624             remove_short(h, pic->frame_num, 0);
 625         }
 626     }
 627
 628     print_short_term(h);
 629     print_long_term(h);
 630     return 0;
 631 }
 632
 633 int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb){
 634     MpegEncContext * const s = &h->s;
 635     int i;
 636
 637     h->mmco_index= 0;
 638     if(h->nal_unit_type == NAL_IDR_SLICE){ //FIXME fields
 639         s->broken_link= get_bits1(gb) -1;
 640         if(get_bits1(gb)){
 641             h->mmco[0].opcode= MMCO_LONG;
 642             h->mmco[0].long_arg= 0;
 643             h->mmco_index= 1;
 644         }
 645     }else{
 646         if(get_bits1(gb)){ // adaptive_ref_pic_marking_mode_flag
 647             for(i= 0; i<MAX_MMCO_COUNT; i++) {
 648                 MMCOOpcode opcode= get_ue_golomb_31(gb);
 649
 650                 h->mmco[i].opcode= opcode;
 651                 if(opcode==MMCO_SHORT2UNUSED || opcode==MMCO_SHORT2LONG){
 652                     h->mmco[i].short_pic_num= (h->curr_pic_num - get_ue_golomb(gb) - 1) & (h->max_pic_num - 1);
 653 /*                    if(h->mmco[i].short_pic_num >= h->short_ref_count || h->short_ref[ h->mmco[i].short_pic_num ] == NULL){
 654                         av_log(s->avctx, AV_LOG_ERROR, "illegal short ref in memory management control operation %d\n", mmco);
 655                         return -1;
 656                     }*/
 657                 }
 658                 if(opcode==MMCO_SHORT2LONG || opcode==MMCO_LONG2UNUSED || opcode==MMCO_LONG || opcode==MMCO_SET_MAX_LONG){
 659                     unsigned int long_arg= get_ue_golomb_31(gb);
 660                     if(long_arg >= 32 || (long_arg >= 16 && !(opcode == MMCO_LONG2UNUSED && FIELD_PICTURE))){
 661                         av_log(h->s.avctx, AV_LOG_ERROR, "illegal long ref in memory management control operation %d\n", opcode);
 662                         return -1;
 663                     }
 664                     h->mmco[i].long_arg= long_arg;
 665                 }
 666
 667                 if(opcode > (unsigned)MMCO_LONG){
 668                     av_log(h->s.avctx, AV_LOG_ERROR, "illegal memory management control operation %d\n", opcode);
 669                     return -1;
 670                 }
 671                 if(opcode == MMCO_END)
 672                     break;
 673             }
 674             h->mmco_index= i;
 675         }else{
 676             assert(h->long_ref_count + h->short_ref_count <= h->sps.ref_frame_count);
 677
 678             if(h->short_ref_count && h->long_ref_count + h->short_ref_count == h->sps.ref_frame_count &&
 679                     !(FIELD_PICTURE && !s->first_field && s->current_picture_ptr->reference)) {
 680                 h->mmco[0].opcode= MMCO_SHORT2UNUSED;
 681                 h->mmco[0].short_pic_num= h->short_ref[ h->short_ref_count - 1 ]->frame_num;
 682                 h->mmco_index= 1;
 683                 if (FIELD_PICTURE) {
 684                     h->mmco[0].short_pic_num *= 2;
 685                     h->mmco[1].opcode= MMCO_SHORT2UNUSED;
 686                     h->mmco[1].short_pic_num= h->mmco[0].short_pic_num + 1;
 687                     h->mmco_index= 2;
 688                 }
 689             }
 690         }
 691     }
 692
 693     return 0;
 694 }