libavformat/nutdec.c

   1 /*
   2  * "NUT" Container Format demuxer
   3  * Copyright (c) 2004-2006 Michael Niedermayer
   4  * Copyright (c) 2003 Alex Beregszaszi
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "tree.h"
  24 #include "nut.h"
  25 #include "avstring.h"
  26
  27 #undef NDEBUG
  28 #include <assert.h>
  29
  30 static int get_str(ByteIOContext *bc, char *string, unsigned int maxlen){
  31     unsigned int len= ff_get_v(bc);
  32
  33     if(len && maxlen)
  34         get_buffer(bc, string, FFMIN(len, maxlen));
  35     while(len > maxlen){
  36         get_byte(bc);
  37         len--;
  38     }
  39
  40     if(maxlen)
  41         string[FFMIN(len, maxlen-1)]= 0;
  42
  43     if(maxlen == len)
  44         return -1;
  45     else
  46         return 0;
  47 }
  48
  49 static int64_t get_s(ByteIOContext *bc){
  50     int64_t v = ff_get_v(bc) + 1;
  51
  52     if (v&1) return -(v>>1);
  53     else     return  (v>>1);
  54 }
  55
  56 static uint64_t get_fourcc(ByteIOContext *bc){
  57     unsigned int len= ff_get_v(bc);
  58
  59     if     (len==2) return get_le16(bc);
  60     else if(len==4) return get_le32(bc);
  61     else            return -1;
  62 }
  63
  64 #ifdef TRACE
  65 static inline uint64_t get_v_trace(ByteIOContext *bc, char *file, char *func, int line){
  66     uint64_t v= ff_get_v(bc);
  67
  68     av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  69     return v;
  70 }
  71
  72 static inline int64_t get_s_trace(ByteIOContext *bc, char *file, char *func, int line){
  73     int64_t v= get_s(bc);
  74
  75     av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  76     return v;
  77 }
  78
  79 static inline uint64_t get_vb_trace(ByteIOContext *bc, char *file, char *func, int line){
  80     uint64_t v= get_vb(bc);
  81
  82     av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  83     return v;
  84 }
  85 #define ff_get_v(bc)  get_v_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  86 #define get_s(bc)  get_s_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  87 #define get_vb(bc)  get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  88 #endif
  89
  90 static int get_packetheader(NUTContext *nut, ByteIOContext *bc, int calculate_checksum, uint64_t startcode)
  91 {
  92     int64_t size;
  93 //    start= url_ftell(bc) - 8;
  94
  95     startcode= be2me_64(startcode);
  96     startcode= ff_crc04C11DB7_update(0, &startcode, 8);
  97
  98     init_checksum(bc, ff_crc04C11DB7_update, startcode);
  99     size= ff_get_v(bc);
 100     if(size > 4096)
 101         get_be32(bc);
 102     if(get_checksum(bc) && size > 4096)
 103         return -1;
 104
 105     init_checksum(bc, calculate_checksum ? ff_crc04C11DB7_update : NULL, 0);
 106
 107     return size;
 108 }
 109
 110 static uint64_t find_any_startcode(ByteIOContext *bc, int64_t pos){
 111     uint64_t state=0;
 112
 113     if(pos >= 0)
 114         url_fseek(bc, pos, SEEK_SET); //note, this may fail if the stream is not seekable, but that should not matter, as in this case we simply start where we are currently
 115
 116     while(!url_feof(bc)){
 117         state= (state<<8) | get_byte(bc);
 118         if((state>>56) != 'N')
 119             continue;
 120         switch(state){
 121         case MAIN_STARTCODE:
 122         case STREAM_STARTCODE:
 123         case SYNCPOINT_STARTCODE:
 124         case INFO_STARTCODE:
 125         case INDEX_STARTCODE:
 126             return state;
 127         }
 128     }
 129
 130     return 0;
 131 }
 132
 133 /**
 134  * Find the given startcode.
 135  * @param code the startcode
 136  * @param pos the start position of the search, or -1 if the current position
 137  * @returns the position of the startcode or -1 if not found
 138  */
 139 static int64_t find_startcode(ByteIOContext *bc, uint64_t code, int64_t pos){
 140     for(;;){
 141         uint64_t startcode= find_any_startcode(bc, pos);
 142         if(startcode == code)
 143             return url_ftell(bc) - 8;
 144         else if(startcode == 0)
 145             return -1;
 146         pos=-1;
 147     }
 148 }
 149
 150 static int nut_probe(AVProbeData *p){
 151     int i;
 152     uint64_t code= 0;
 153
 154     for (i = 0; i < p->buf_size; i++) {
 155         code = (code << 8) | p->buf[i];
 156         if (code == MAIN_STARTCODE)
 157             return AVPROBE_SCORE_MAX;
 158     }
 159     return 0;
 160 }
 161
 162 #define GET_V(dst, check) \
 163     tmp= ff_get_v(bc);\
 164     if(!(check)){\
 165         av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\
 166         return -1;\
 167     }\
 168     dst= tmp;
 169
 170 static int skip_reserved(ByteIOContext *bc, int64_t pos){
 171     pos -= url_ftell(bc);
 172     if(pos<0){
 173         url_fseek(bc, pos, SEEK_CUR);
 174         return -1;
 175     }else{
 176         while(pos--)
 177             get_byte(bc);
 178         return 0;
 179     }
 180 }
 181
 182 static int decode_main_header(NUTContext *nut){
 183     AVFormatContext *s= nut->avf;
 184     ByteIOContext *bc = s->pb;
 185     uint64_t tmp, end;
 186     unsigned int stream_count;
 187     int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res;
 188
 189     end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);
 190     end += url_ftell(bc);
 191
 192     GET_V(tmp              , tmp >=2 && tmp <= 3)
 193     GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)
 194
 195     nut->max_distance = ff_get_v(bc);
 196     if(nut->max_distance > 65536){
 197         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
 198         nut->max_distance= 65536;
 199     }
 200
 201     GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
 202     nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));
 203
 204     for(i=0; i<nut->time_base_count; i++){
 205         GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
 206         GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
 207         if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
 208             av_log(s, AV_LOG_ERROR, "time base invalid\n");
 209             return -1;
 210         }
 211     }
 212     tmp_pts=0;
 213     tmp_mul=1;
 214     tmp_stream=0;
 215     for(i=0; i<256;){
 216         int tmp_flags = ff_get_v(bc);
 217         int tmp_fields= ff_get_v(bc);
 218         if(tmp_fields>0) tmp_pts   = get_s(bc);
 219         if(tmp_fields>1) tmp_mul   = ff_get_v(bc);
 220         if(tmp_fields>2) tmp_stream= ff_get_v(bc);
 221         if(tmp_fields>3) tmp_size  = ff_get_v(bc);
 222         else             tmp_size  = 0;
 223         if(tmp_fields>4) tmp_res   = ff_get_v(bc);
 224         else             tmp_res   = 0;
 225         if(tmp_fields>5) count     = ff_get_v(bc);
 226         else             count     = tmp_mul - tmp_size;
 227
 228         while(tmp_fields-- > 6)
 229            ff_get_v(bc);
 230
 231         if(count == 0 || i+count > 256){
 232             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
 233             return -1;
 234         }
 235         if(tmp_stream >= stream_count){
 236             av_log(s, AV_LOG_ERROR, "illegal stream number\n");
 237             return -1;
 238         }
 239
 240         for(j=0; j<count; j++,i++){
 241             if (i == 'N') {
 242                 nut->frame_code[i].flags= FLAG_INVALID;
 243                 j--;
 244                 continue;
 245             }
 246             nut->frame_code[i].flags           = tmp_flags ;
 247             nut->frame_code[i].pts_delta       = tmp_pts   ;
 248             nut->frame_code[i].stream_id       = tmp_stream;
 249             nut->frame_code[i].size_mul        = tmp_mul   ;
 250             nut->frame_code[i].size_lsb        = tmp_size+j;
 251             nut->frame_code[i].reserved_count  = tmp_res   ;
 252         }
 253     }
 254     assert(nut->frame_code['N'].flags == FLAG_INVALID);
 255
 256     if(skip_reserved(bc, end) || get_checksum(bc)){
 257         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
 258         return -1;
 259     }
 260
 261     nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
 262     for(i=0; i<stream_count; i++){
 263         av_new_stream(s, i);
 264     }
 265
 266     return 0;
 267 }
 268
 269 static int decode_stream_header(NUTContext *nut){
 270     AVFormatContext *s= nut->avf;
 271     ByteIOContext *bc = s->pb;
 272     StreamContext *stc;
 273     int class, stream_id;
 274     uint64_t tmp, end;
 275     AVStream *st;
 276
 277     end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);
 278     end += url_ftell(bc);
 279
 280     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
 281     stc= &nut->stream[stream_id];
 282
 283     st = s->streams[stream_id];
 284     if (!st)
 285         return AVERROR(ENOMEM);
 286
 287     class = ff_get_v(bc);
 288     tmp = get_fourcc(bc);
 289     st->codec->codec_tag= tmp;
 290     switch(class)
 291     {
 292         case 0:
 293             st->codec->codec_type = CODEC_TYPE_VIDEO;
 294             st->codec->codec_id = codec_get_id(codec_bmp_tags, tmp);
 295             if (st->codec->codec_id == CODEC_ID_NONE)
 296                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
 297             break;
 298         case 1:
 299             st->codec->codec_type = CODEC_TYPE_AUDIO;
 300             st->codec->codec_id = codec_get_id(codec_wav_tags, tmp);
 301             if (st->codec->codec_id == CODEC_ID_NONE)
 302                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
 303             break;
 304         case 2:
 305 //            st->codec->codec_type = CODEC_TYPE_TEXT;
 306 //            break;
 307         case 3:
 308             st->codec->codec_type = CODEC_TYPE_DATA;
 309             break;
 310         default:
 311             av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
 312             return -1;
 313     }
 314     GET_V(stc->time_base_id    , tmp < nut->time_base_count);
 315     GET_V(stc->msb_pts_shift   , tmp < 16);
 316     stc->max_pts_distance= ff_get_v(bc);
 317     GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true
 318     st->codec->has_b_frames= stc->decode_delay;
 319     ff_get_v(bc); //stream flags
 320
 321     GET_V(st->codec->extradata_size, tmp < (1<<30));
 322     if(st->codec->extradata_size){
 323         st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
 324         get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
 325     }
 326
 327     if (st->codec->codec_type == CODEC_TYPE_VIDEO){
 328         GET_V(st->codec->width , tmp > 0)
 329         GET_V(st->codec->height, tmp > 0)
 330         st->codec->sample_aspect_ratio.num= ff_get_v(bc);
 331         st->codec->sample_aspect_ratio.den= ff_get_v(bc);
 332         if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
 333             av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n", st->codec->sample_aspect_ratio.num, st->codec->sample_aspect_ratio.den);
 334             return -1;
 335         }
 336         ff_get_v(bc); /* csp type */
 337     }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
 338         GET_V(st->codec->sample_rate , tmp > 0)
 339         ff_get_v(bc); // samplerate_den
 340         GET_V(st->codec->channels, tmp > 0)
 341     }
 342     if(skip_reserved(bc, end) || get_checksum(bc)){
 343         av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);
 344         return -1;
 345     }
 346     stc->time_base= &nut->time_base[stc->time_base_id];
 347     av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);
 348     return 0;
 349 }
 350
 351 static int decode_info_header(NUTContext *nut){
 352     AVFormatContext *s= nut->avf;
 353     ByteIOContext *bc = s->pb;
 354     uint64_t tmp;
 355     unsigned int stream_id_plus1, chapter_start, chapter_len, count;
 356     int chapter_id, i;
 357     int64_t value, end;
 358     char name[256], str_value[1024], type_str[256];
 359     const char *type;
 360
 361     end= get_packetheader(nut, bc, 1, INFO_STARTCODE);
 362     end += url_ftell(bc);
 363
 364     GET_V(stream_id_plus1, tmp <= s->nb_streams)
 365     chapter_id   = get_s(bc);
 366     chapter_start= ff_get_v(bc);
 367     chapter_len  = ff_get_v(bc);
 368     count        = ff_get_v(bc);
 369     for(i=0; i<count; i++){
 370         get_str(bc, name, sizeof(name));
 371         value= get_s(bc);
 372         if(value == -1){
 373             type= "UTF-8";
 374             get_str(bc, str_value, sizeof(str_value));
 375         }else if(value == -2){
 376             get_str(bc, type_str, sizeof(type_str));
 377             type= type_str;
 378             get_str(bc, str_value, sizeof(str_value));
 379         }else if(value == -3){
 380             type= "s";
 381             value= get_s(bc);
 382         }else if(value == -4){
 383             type= "t";
 384             value= ff_get_v(bc);
 385         }else if(value < -4){
 386             type= "r";
 387             get_s(bc);
 388         }else{
 389             type= "v";
 390         }
 391
 392         if(chapter_id==0 && !strcmp(type, "UTF-8")){
 393             if     (!strcmp(name, "Author"))
 394                 av_strlcpy(s->author   , str_value, sizeof(s->author));
 395             else if(!strcmp(name, "Title"))
 396                 av_strlcpy(s->title    , str_value, sizeof(s->title));
 397             else if(!strcmp(name, "Copyright"))
 398                 av_strlcpy(s->copyright, str_value, sizeof(s->copyright));
 399             else if(!strcmp(name, "Description"))
 400                 av_strlcpy(s->comment  , str_value, sizeof(s->comment));
 401         }
 402     }
 403
 404     if(skip_reserved(bc, end) || get_checksum(bc)){
 405         av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
 406         return -1;
 407     }
 408     return 0;
 409 }
 410
 411 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
 412     AVFormatContext *s= nut->avf;
 413     ByteIOContext *bc = s->pb;
 414     int64_t end, tmp;
 415
 416     nut->last_syncpoint_pos= url_ftell(bc)-8;
 417
 418     end= get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);
 419     end += url_ftell(bc);
 420
 421     tmp= ff_get_v(bc);
 422     *back_ptr= nut->last_syncpoint_pos - 16*ff_get_v(bc);
 423     if(*back_ptr < 0)
 424         return -1;
 425
 426     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count], tmp / nut->time_base_count);
 427
 428     if(skip_reserved(bc, end) || get_checksum(bc)){
 429         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
 430         return -1;
 431     }
 432
 433     *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;
 434     ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);
 435
 436     return 0;
 437 }
 438
 439 static int find_and_decode_index(NUTContext *nut){
 440     AVFormatContext *s= nut->avf;
 441     ByteIOContext *bc = s->pb;
 442     uint64_t tmp, end;
 443     int i, j, syncpoint_count;
 444     int64_t filesize= url_fsize(bc);
 445     int64_t *syncpoints;
 446     int8_t *has_keyframe;
 447
 448     url_fseek(bc, filesize-12, SEEK_SET);
 449     url_fseek(bc, filesize-get_be64(bc), SEEK_SET);
 450     if(get_be64(bc) != INDEX_STARTCODE){
 451         av_log(s, AV_LOG_ERROR, "no index at the end\n");
 452         return -1;
 453     }
 454
 455     end= get_packetheader(nut, bc, 1, INDEX_STARTCODE);
 456     end += url_ftell(bc);
 457
 458     ff_get_v(bc); //max_pts
 459     GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)
 460     syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);
 461     has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));
 462     for(i=0; i<syncpoint_count; i++){
 463         GET_V(syncpoints[i], tmp>0)
 464         if(i)
 465             syncpoints[i] += syncpoints[i-1];
 466     }
 467
 468     for(i=0; i<s->nb_streams; i++){
 469         int64_t last_pts= -1;
 470         for(j=0; j<syncpoint_count;){
 471             uint64_t x= ff_get_v(bc);
 472             int type= x&1;
 473             int n= j;
 474             x>>=1;
 475             if(type){
 476                 int flag= x&1;
 477                 x>>=1;
 478                 if(n+x >= syncpoint_count + 1){
 479                     av_log(s, AV_LOG_ERROR, "index overflow A\n");
 480                     return -1;
 481                 }
 482                 while(x--)
 483                     has_keyframe[n++]= flag;
 484                 has_keyframe[n++]= !flag;
 485             }else{
 486                 while(x != 1){
 487                     if(n>=syncpoint_count + 1){
 488                         av_log(s, AV_LOG_ERROR, "index overflow B\n");
 489                         return -1;
 490                     }
 491                     has_keyframe[n++]= x&1;
 492                     x>>=1;
 493                 }
 494             }
 495             if(has_keyframe[0]){
 496                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
 497                 return -1;
 498             }
 499             assert(n<=syncpoint_count+1);
 500             for(; j<n && j<syncpoint_count; j++){
 501                 if(has_keyframe[j]){
 502                     uint64_t B, A= ff_get_v(bc);
 503                     if(!A){
 504                         A= ff_get_v(bc);
 505                         B= ff_get_v(bc);
 506                         //eor_pts[j][i] = last_pts + A + B
 507                     }else
 508                         B= 0;
 509                     av_add_index_entry(
 510                         s->streams[i],
 511                         16*syncpoints[j-1],
 512                         last_pts + A,
 513                         0,
 514                         0,
 515                         AVINDEX_KEYFRAME);
 516                     last_pts += A + B;
 517                 }
 518             }
 519         }
 520     }
 521
 522     if(skip_reserved(bc, end) || get_checksum(bc)){
 523         av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");
 524         return -1;
 525     }
 526     return 0;
 527 }
 528
 529 static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
 530 {
 531     NUTContext *nut = s->priv_data;
 532     ByteIOContext *bc = s->pb;
 533     int64_t pos;
 534     int initialized_stream_count;
 535
 536     nut->avf= s;
 537
 538     /* main header */
 539     pos=0;
 540     do{
 541         pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
 542         if (pos<0+1){
 543             av_log(s, AV_LOG_ERROR, "No main startcode found.\n");
 544             return -1;
 545         }
 546     }while(decode_main_header(nut) < 0);
 547
 548     /* stream headers */
 549     pos=0;
 550     for(initialized_stream_count=0; initialized_stream_count < s->nb_streams;){
 551         pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
 552         if (pos<0+1){
 553             av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");
 554             return -1;
 555         }
 556         if(decode_stream_header(nut) >= 0)
 557             initialized_stream_count++;
 558     }
 559
 560     /* info headers */
 561     pos=0;
 562     for(;;){
 563         uint64_t startcode= find_any_startcode(bc, pos);
 564         pos= url_ftell(bc);
 565
 566         if(startcode==0){
 567             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
 568             return -1;
 569         }else if(startcode == SYNCPOINT_STARTCODE){
 570             nut->next_startcode= startcode;
 571             break;
 572         }else if(startcode != INFO_STARTCODE){
 573             continue;
 574         }
 575
 576         decode_info_header(nut);
 577     }
 578
 579     s->data_offset= pos-8;
 580
 581     if(!url_is_streamed(bc)){
 582         int64_t orig_pos= url_ftell(bc);
 583         find_and_decode_index(nut);
 584         url_fseek(bc, orig_pos, SEEK_SET);
 585     }
 586     assert(nut->next_startcode == SYNCPOINT_STARTCODE);
 587
 588     return 0;
 589 }
 590
 591 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, int frame_code){
 592     AVFormatContext *s= nut->avf;
 593     ByteIOContext *bc = s->pb;
 594     StreamContext *stc;
 595     int size, flags, size_mul, pts_delta, i, reserved_count;
 596     uint64_t tmp;
 597
 598     if(url_ftell(bc) > nut->last_syncpoint_pos + nut->max_distance){
 599         av_log(s, AV_LOG_ERROR, "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n", url_ftell(bc), nut->last_syncpoint_pos, nut->max_distance);
 600         return -1;
 601     }
 602
 603     flags          = nut->frame_code[frame_code].flags;
 604     size_mul       = nut->frame_code[frame_code].size_mul;
 605     size           = nut->frame_code[frame_code].size_lsb;
 606     *stream_id     = nut->frame_code[frame_code].stream_id;
 607     pts_delta      = nut->frame_code[frame_code].pts_delta;
 608     reserved_count = nut->frame_code[frame_code].reserved_count;
 609
 610     if(flags & FLAG_INVALID)
 611         return -1;
 612     if(flags & FLAG_CODED)
 613         flags ^= ff_get_v(bc);
 614     if(flags & FLAG_STREAM_ID){
 615         GET_V(*stream_id, tmp < s->nb_streams)
 616     }
 617     stc= &nut->stream[*stream_id];
 618     if(flags&FLAG_CODED_PTS){
 619         int coded_pts= ff_get_v(bc);
 620 //FIXME check last_pts validity?
 621         if(coded_pts < (1<<stc->msb_pts_shift)){
 622             *pts=ff_lsb2full(stc, coded_pts);
 623         }else
 624             *pts=coded_pts - (1<<stc->msb_pts_shift);
 625     }else
 626         *pts= stc->last_pts + pts_delta;
 627     if(flags&FLAG_SIZE_MSB){
 628         size += size_mul*ff_get_v(bc);
 629     }
 630     if(flags&FLAG_RESERVED)
 631         reserved_count= ff_get_v(bc);
 632     for(i=0; i<reserved_count; i++)
 633         ff_get_v(bc);
 634     if(flags&FLAG_CHECKSUM){
 635         get_be32(bc); //FIXME check this
 636     }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){
 637         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
 638         return -1;
 639     }
 640
 641     stc->last_pts= *pts;
 642     stc->last_flags= flags;
 643
 644     return size;
 645 }
 646
 647 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){
 648     AVFormatContext *s= nut->avf;
 649     ByteIOContext *bc = s->pb;
 650     int size, stream_id, discard;
 651     int64_t pts, last_IP_pts;
 652     StreamContext *stc;
 653
 654     size= decode_frame_header(nut, &pts, &stream_id, frame_code);
 655     if(size < 0)
 656         return -1;
 657
 658     stc= &nut->stream[stream_id];
 659
 660     if (stc->last_flags & FLAG_KEY)
 661         stc->skip_until_key_frame=0;
 662
 663     discard= s->streams[ stream_id ]->discard;
 664     last_IP_pts= s->streams[ stream_id ]->last_IP_pts;
 665     if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))
 666        ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)
 667        || discard >= AVDISCARD_ALL
 668        || stc->skip_until_key_frame){
 669         url_fskip(bc, size);
 670         return 1;
 671     }
 672
 673     av_get_packet(bc, pkt, size);
 674     pkt->stream_index = stream_id;
 675     if (stc->last_flags & FLAG_KEY)
 676         pkt->flags |= PKT_FLAG_KEY;
 677     pkt->pts = pts;
 678
 679     return 0;
 680 }
 681
 682 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
 683 {
 684     NUTContext *nut = s->priv_data;
 685     ByteIOContext *bc = s->pb;
 686     int i, frame_code=0, ret, skip;
 687     int64_t ts, back_ptr;
 688
 689     for(;;){
 690         int64_t pos= url_ftell(bc);
 691         uint64_t tmp= nut->next_startcode;
 692         nut->next_startcode=0;
 693
 694         if(tmp){
 695             pos-=8;
 696         }else{
 697             frame_code = get_byte(bc);
 698             if(url_feof(bc))
 699                 return -1;
 700             if(frame_code == 'N'){
 701                 tmp= frame_code;
 702                 for(i=1; i<8; i++)
 703                     tmp = (tmp<<8) + get_byte(bc);
 704             }
 705         }
 706         switch(tmp){
 707         case MAIN_STARTCODE:
 708         case STREAM_STARTCODE:
 709         case INDEX_STARTCODE:
 710             skip= get_packetheader(nut, bc, 0, tmp);
 711             url_fseek(bc, skip, SEEK_CUR);
 712             break;
 713         case INFO_STARTCODE:
 714             if(decode_info_header(nut)<0)
 715                 goto resync;
 716             break;
 717         case SYNCPOINT_STARTCODE:
 718             if(decode_syncpoint(nut, &ts, &back_ptr)<0)
 719                 goto resync;
 720             frame_code = get_byte(bc);
 721         case 0:
 722             ret= decode_frame(nut, pkt, frame_code);
 723             if(ret==0)
 724                 return 0;
 725             else if(ret==1) //ok but discard packet
 726                 break;
 727         default:
 728 resync:
 729 av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
 730             tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);
 731             if(tmp==0)
 732                 return -1;
 733 av_log(s, AV_LOG_DEBUG, "sync\n");
 734             nut->next_startcode= tmp;
 735         }
 736     }
 737 }
 738
 739 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
 740     NUTContext *nut = s->priv_data;
 741     ByteIOContext *bc = s->pb;
 742     int64_t pos, pts, back_ptr;
 743 av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);
 744
 745     pos= *pos_arg;
 746     do{
 747         pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;
 748         if(pos < 1){
 749             assert(nut->next_startcode == 0);
 750             av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");
 751             return AV_NOPTS_VALUE;
 752         }
 753     }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);
 754     *pos_arg = pos-1;
 755     assert(nut->last_syncpoint_pos == *pos_arg);
 756
 757     av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts,back_ptr );
 758     if     (stream_index == -1) return pts;
 759     else if(stream_index == -2) return back_ptr;
 760
 761 assert(0);
 762 }
 763
 764 static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){
 765     NUTContext *nut = s->priv_data;
 766     AVStream *st= s->streams[stream_index];
 767     syncpoint_t dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};
 768     syncpoint_t nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};
 769     syncpoint_t *sp, *next_node[2]= {&nopts_sp, &nopts_sp};
 770     int64_t pos, pos2, ts;
 771     int i;
 772
 773     if(st->index_entries){
 774         int index= av_index_search_timestamp(st, pts, flags);
 775         if(index<0)
 776             return -1;
 777
 778         pos2= st->index_entries[index].pos;
 779         ts  = st->index_entries[index].timestamp;
 780     }else{
 781         av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp, next_node);
 782         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,
 783                                                     next_node[0]->ts , next_node[1]->ts);
 784         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
 785                                             next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
 786
 787         if(!(flags & AVSEEK_FLAG_BACKWARD)){
 788             dummy.pos= pos+16;
 789             next_node[1]= &nopts_sp;
 790             av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, next_node);
 791             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
 792                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
 793             if(pos2>=0)
 794                 pos= pos2;
 795             //FIXME dir but i think it does not matter
 796         }
 797         dummy.pos= pos;
 798         sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
 799
 800         assert(sp);
 801         pos2= sp->back_ptr  - 15;
 802     }
 803     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
 804     pos= find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);
 805     url_fseek(s->pb, pos, SEEK_SET);
 806     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
 807     if(pos2 > pos || pos2 + 15 < pos){
 808         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
 809     }
 810     for(i=0; i<s->nb_streams; i++)
 811         nut->stream[i].skip_until_key_frame=1;
 812
 813     return 0;
 814 }
 815
 816 static int nut_read_close(AVFormatContext *s)
 817 {
 818     NUTContext *nut = s->priv_data;
 819
 820     av_freep(&nut->time_base);
 821     av_freep(&nut->stream);
 822
 823     return 0;
 824 }
 825
 826 #ifdef CONFIG_NUT_DEMUXER
 827 AVInputFormat nut_demuxer = {
 828     "nut",
 829     "nut format",
 830     sizeof(NUTContext),
 831     nut_probe,
 832     nut_read_header,
 833     nut_read_packet,
 834     nut_read_close,
 835     read_seek,
 836     .extensions = "nut",
 837 };
 838 #endif