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 "libavutil/avstring.h"
  24 #include "libavutil/tree.h"
  25 #include "nut.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 currently are
 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, tmp_head_idx;
 188     int64_t tmp_match;
 189
 190     end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);
 191     end += url_ftell(bc);
 192
 193     GET_V(tmp              , tmp >=2 && tmp <= 3)
 194     GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)
 195
 196     nut->max_distance = ff_get_v(bc);
 197     if(nut->max_distance > 65536){
 198         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
 199         nut->max_distance= 65536;
 200     }
 201
 202     GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
 203     nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));
 204
 205     for(i=0; i<nut->time_base_count; i++){
 206         GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
 207         GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
 208         if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
 209             av_log(s, AV_LOG_ERROR, "time base invalid\n");
 210             return -1;
 211         }
 212     }
 213     tmp_pts=0;
 214     tmp_mul=1;
 215     tmp_stream=0;
 216     tmp_match= 1-(1LL<<62);
 217     tmp_head_idx= 0;
 218     for(i=0; i<256;){
 219         int tmp_flags = ff_get_v(bc);
 220         int tmp_fields= ff_get_v(bc);
 221         if(tmp_fields>0) tmp_pts   = get_s(bc);
 222         if(tmp_fields>1) tmp_mul   = ff_get_v(bc);
 223         if(tmp_fields>2) tmp_stream= ff_get_v(bc);
 224         if(tmp_fields>3) tmp_size  = ff_get_v(bc);
 225         else             tmp_size  = 0;
 226         if(tmp_fields>4) tmp_res   = ff_get_v(bc);
 227         else             tmp_res   = 0;
 228         if(tmp_fields>5) count     = ff_get_v(bc);
 229         else             count     = tmp_mul - tmp_size;
 230         if(tmp_fields>6) tmp_match = get_s(bc);
 231         if(tmp_fields>7) tmp_head_idx= ff_get_v(bc);
 232
 233         while(tmp_fields-- > 8)
 234            ff_get_v(bc);
 235
 236         if(count == 0 || i+count > 256){
 237             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
 238             return -1;
 239         }
 240         if(tmp_stream >= stream_count){
 241             av_log(s, AV_LOG_ERROR, "illegal stream number\n");
 242             return -1;
 243         }
 244
 245         for(j=0; j<count; j++,i++){
 246             if (i == 'N') {
 247                 nut->frame_code[i].flags= FLAG_INVALID;
 248                 j--;
 249                 continue;
 250             }
 251             nut->frame_code[i].flags           = tmp_flags ;
 252             nut->frame_code[i].pts_delta       = tmp_pts   ;
 253             nut->frame_code[i].stream_id       = tmp_stream;
 254             nut->frame_code[i].size_mul        = tmp_mul   ;
 255             nut->frame_code[i].size_lsb        = tmp_size+j;
 256             nut->frame_code[i].reserved_count  = tmp_res   ;
 257             nut->frame_code[i].header_idx      = tmp_head_idx;
 258         }
 259     }
 260     assert(nut->frame_code['N'].flags == FLAG_INVALID);
 261
 262     if(end > url_ftell(bc) + 4){
 263         int rem= 1024;
 264         GET_V(nut->header_count, tmp<128U)
 265         nut->header_count++;
 266         for(i=1; i<nut->header_count; i++){
 267             GET_V(nut->header_len[i], tmp>0 && tmp<256);
 268             rem -= nut->header_len[i];
 269             if(rem < 0){
 270                 av_log(s, AV_LOG_ERROR, "invalid elision header\n");
 271                 return -1;
 272             }
 273             nut->header[i]= av_malloc(nut->header_len[i]);
 274             get_buffer(bc, nut->header[i], nut->header_len[i]);
 275         }
 276         assert(nut->header_len[0]==0);
 277     }
 278
 279     if(skip_reserved(bc, end) || get_checksum(bc)){
 280         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
 281         return -1;
 282     }
 283
 284     nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
 285     for(i=0; i<stream_count; i++){
 286         av_new_stream(s, i);
 287     }
 288
 289     return 0;
 290 }
 291
 292 static int decode_stream_header(NUTContext *nut){
 293     AVFormatContext *s= nut->avf;
 294     ByteIOContext *bc = s->pb;
 295     StreamContext *stc;
 296     int class, stream_id;
 297     uint64_t tmp, end;
 298     AVStream *st;
 299
 300     end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);
 301     end += url_ftell(bc);
 302
 303     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
 304     stc= &nut->stream[stream_id];
 305
 306     st = s->streams[stream_id];
 307     if (!st)
 308         return AVERROR(ENOMEM);
 309
 310     class = ff_get_v(bc);
 311     tmp = get_fourcc(bc);
 312     st->codec->codec_tag= tmp;
 313     switch(class)
 314     {
 315         case 0:
 316             st->codec->codec_type = CODEC_TYPE_VIDEO;
 317             st->codec->codec_id = codec_get_id(codec_bmp_tags, tmp);
 318             break;
 319         case 1:
 320             st->codec->codec_type = CODEC_TYPE_AUDIO;
 321             st->codec->codec_id = codec_get_id(codec_wav_tags, tmp);
 322             break;
 323         case 2:
 324             st->codec->codec_type = CODEC_TYPE_SUBTITLE;
 325             st->codec->codec_id = codec_get_id(ff_nut_subtitle_tags, tmp);
 326             break;
 327         case 3:
 328             st->codec->codec_type = CODEC_TYPE_DATA;
 329             break;
 330         default:
 331             av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
 332             return -1;
 333     }
 334     if(class<3 && st->codec->codec_id == CODEC_ID_NONE)
 335         av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
 336
 337     GET_V(stc->time_base_id    , tmp < nut->time_base_count);
 338     GET_V(stc->msb_pts_shift   , tmp < 16);
 339     stc->max_pts_distance= ff_get_v(bc);
 340     GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true
 341     st->codec->has_b_frames= stc->decode_delay;
 342     ff_get_v(bc); //stream flags
 343
 344     GET_V(st->codec->extradata_size, tmp < (1<<30));
 345     if(st->codec->extradata_size){
 346         st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
 347         get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
 348     }
 349
 350     if (st->codec->codec_type == CODEC_TYPE_VIDEO){
 351         GET_V(st->codec->width , tmp > 0)
 352         GET_V(st->codec->height, tmp > 0)
 353         st->codec->sample_aspect_ratio.num= ff_get_v(bc);
 354         st->codec->sample_aspect_ratio.den= ff_get_v(bc);
 355         if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
 356             av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n", st->codec->sample_aspect_ratio.num, st->codec->sample_aspect_ratio.den);
 357             return -1;
 358         }
 359         ff_get_v(bc); /* csp type */
 360     }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
 361         GET_V(st->codec->sample_rate , tmp > 0)
 362         ff_get_v(bc); // samplerate_den
 363         GET_V(st->codec->channels, tmp > 0)
 364     }
 365     if(skip_reserved(bc, end) || get_checksum(bc)){
 366         av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);
 367         return -1;
 368     }
 369     stc->time_base= &nut->time_base[stc->time_base_id];
 370     av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);
 371     return 0;
 372 }
 373
 374 static void set_disposition_bits(AVFormatContext* avf, char* value, int stream_id){
 375     int flag = 0, i;
 376     for (i=0; ff_nut_dispositions[i].flag; ++i) {
 377         if (!strcmp(ff_nut_dispositions[i].str, value))
 378             flag = ff_nut_dispositions[i].flag;
 379     }
 380     if (!flag)
 381         av_log(avf, AV_LOG_INFO, "unknown disposition type '%s'\n", value);
 382     for (i = 0; i < avf->nb_streams; ++i)
 383         if (stream_id == i || stream_id == -1)
 384             avf->streams[i]->disposition |= flag;
 385 }
 386
 387 static int decode_info_header(NUTContext *nut){
 388     AVFormatContext *s= nut->avf;
 389     ByteIOContext *bc = s->pb;
 390     uint64_t tmp;
 391     unsigned int stream_id_plus1, chapter_start, chapter_len, count;
 392     int chapter_id, i;
 393     int64_t value, end;
 394     char name[256], str_value[1024], type_str[256];
 395     const char *type;
 396     AVChapter *chapter= NULL;
 397
 398     end= get_packetheader(nut, bc, 1, INFO_STARTCODE);
 399     end += url_ftell(bc);
 400
 401     GET_V(stream_id_plus1, tmp <= s->nb_streams)
 402     chapter_id   = get_s(bc);
 403     chapter_start= ff_get_v(bc);
 404     chapter_len  = ff_get_v(bc);
 405     count        = ff_get_v(bc);
 406
 407     if(chapter_id && !stream_id_plus1){
 408         int64_t start= chapter_start / nut->time_base_count;
 409         chapter= ff_new_chapter(s, chapter_id,
 410                                 nut->time_base[chapter_start % nut->time_base_count],
 411                                 start, start + chapter_len, NULL);
 412     }
 413
 414     for(i=0; i<count; i++){
 415         get_str(bc, name, sizeof(name));
 416         value= get_s(bc);
 417         if(value == -1){
 418             type= "UTF-8";
 419             get_str(bc, str_value, sizeof(str_value));
 420         }else if(value == -2){
 421             get_str(bc, type_str, sizeof(type_str));
 422             type= type_str;
 423             get_str(bc, str_value, sizeof(str_value));
 424         }else if(value == -3){
 425             type= "s";
 426             value= get_s(bc);
 427         }else if(value == -4){
 428             type= "t";
 429             value= ff_get_v(bc);
 430         }else if(value < -4){
 431             type= "r";
 432             get_s(bc);
 433         }else{
 434             type= "v";
 435         }
 436
 437         if (stream_id_plus1 > s->nb_streams) {
 438             av_log(s, AV_LOG_ERROR, "invalid stream id for info packet\n");
 439             continue;
 440         }
 441
 442         if(chapter_id==0 && !strcmp(type, "UTF-8")){
 443             if     (!strcmp(name, "Author"))
 444                 av_strlcpy(s->author   , str_value, sizeof(s->author));
 445             else if(!strcmp(name, "Title"))
 446                 av_strlcpy(s->title    , str_value, sizeof(s->title));
 447             else if(!strcmp(name, "Copyright"))
 448                 av_strlcpy(s->copyright, str_value, sizeof(s->copyright));
 449             else if(!strcmp(name, "Description"))
 450                 av_strlcpy(s->comment  , str_value, sizeof(s->comment));
 451             else if(!strcmp(name, "Disposition"))
 452                 set_disposition_bits(s, str_value, stream_id_plus1 - 1);
 453         }
 454         if(chapter && !strcmp(type, "UTF-8")){
 455             if(!strcmp(name, "Title"))
 456                 chapter->title= av_strdup(str_value);
 457         }
 458     }
 459
 460     if(skip_reserved(bc, end) || get_checksum(bc)){
 461         av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
 462         return -1;
 463     }
 464     return 0;
 465 }
 466
 467 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
 468     AVFormatContext *s= nut->avf;
 469     ByteIOContext *bc = s->pb;
 470     int64_t end, tmp;
 471
 472     nut->last_syncpoint_pos= url_ftell(bc)-8;
 473
 474     end= get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);
 475     end += url_ftell(bc);
 476
 477     tmp= ff_get_v(bc);
 478     *back_ptr= nut->last_syncpoint_pos - 16*ff_get_v(bc);
 479     if(*back_ptr < 0)
 480         return -1;
 481
 482     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count], tmp / nut->time_base_count);
 483
 484     if(skip_reserved(bc, end) || get_checksum(bc)){
 485         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
 486         return -1;
 487     }
 488
 489     *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;
 490     ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);
 491
 492     return 0;
 493 }
 494
 495 static int find_and_decode_index(NUTContext *nut){
 496     AVFormatContext *s= nut->avf;
 497     ByteIOContext *bc = s->pb;
 498     uint64_t tmp, end;
 499     int i, j, syncpoint_count;
 500     int64_t filesize= url_fsize(bc);
 501     int64_t *syncpoints;
 502     int8_t *has_keyframe;
 503     int ret= -1;
 504
 505     url_fseek(bc, filesize-12, SEEK_SET);
 506     url_fseek(bc, filesize-get_be64(bc), SEEK_SET);
 507     if(get_be64(bc) != INDEX_STARTCODE){
 508         av_log(s, AV_LOG_ERROR, "no index at the end\n");
 509         return -1;
 510     }
 511
 512     end= get_packetheader(nut, bc, 1, INDEX_STARTCODE);
 513     end += url_ftell(bc);
 514
 515     ff_get_v(bc); //max_pts
 516     GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)
 517     syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);
 518     has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));
 519     for(i=0; i<syncpoint_count; i++){
 520         syncpoints[i] = ff_get_v(bc);
 521         if(syncpoints[i] <= 0)
 522             goto fail;
 523         if(i)
 524             syncpoints[i] += syncpoints[i-1];
 525     }
 526
 527     for(i=0; i<s->nb_streams; i++){
 528         int64_t last_pts= -1;
 529         for(j=0; j<syncpoint_count;){
 530             uint64_t x= ff_get_v(bc);
 531             int type= x&1;
 532             int n= j;
 533             x>>=1;
 534             if(type){
 535                 int flag= x&1;
 536                 x>>=1;
 537                 if(n+x >= syncpoint_count + 1){
 538                     av_log(s, AV_LOG_ERROR, "index overflow A\n");
 539                     goto fail;
 540                 }
 541                 while(x--)
 542                     has_keyframe[n++]= flag;
 543                 has_keyframe[n++]= !flag;
 544             }else{
 545                 while(x != 1){
 546                     if(n>=syncpoint_count + 1){
 547                         av_log(s, AV_LOG_ERROR, "index overflow B\n");
 548                         goto fail;
 549                     }
 550                     has_keyframe[n++]= x&1;
 551                     x>>=1;
 552                 }
 553             }
 554             if(has_keyframe[0]){
 555                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
 556                 goto fail;
 557             }
 558             assert(n<=syncpoint_count+1);
 559             for(; j<n && j<syncpoint_count; j++){
 560                 if(has_keyframe[j]){
 561                     uint64_t B, A= ff_get_v(bc);
 562                     if(!A){
 563                         A= ff_get_v(bc);
 564                         B= ff_get_v(bc);
 565                         //eor_pts[j][i] = last_pts + A + B
 566                     }else
 567                         B= 0;
 568                     av_add_index_entry(
 569                         s->streams[i],
 570                         16*syncpoints[j-1],
 571                         last_pts + A,
 572                         0,
 573                         0,
 574                         AVINDEX_KEYFRAME);
 575                     last_pts += A + B;
 576                 }
 577             }
 578         }
 579     }
 580
 581     if(skip_reserved(bc, end) || get_checksum(bc)){
 582         av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");
 583         goto fail;
 584     }
 585     ret= 0;
 586 fail:
 587     av_free(syncpoints);
 588     av_free(has_keyframe);
 589     return ret;
 590 }
 591
 592 static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
 593 {
 594     NUTContext *nut = s->priv_data;
 595     ByteIOContext *bc = s->pb;
 596     int64_t pos;
 597     int initialized_stream_count;
 598
 599     nut->avf= s;
 600
 601     /* main header */
 602     pos=0;
 603     do{
 604         pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
 605         if (pos<0+1){
 606             av_log(s, AV_LOG_ERROR, "No main startcode found.\n");
 607             return -1;
 608         }
 609     }while(decode_main_header(nut) < 0);
 610
 611     /* stream headers */
 612     pos=0;
 613     for(initialized_stream_count=0; initialized_stream_count < s->nb_streams;){
 614         pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
 615         if (pos<0+1){
 616             av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");
 617             return -1;
 618         }
 619         if(decode_stream_header(nut) >= 0)
 620             initialized_stream_count++;
 621     }
 622
 623     /* info headers */
 624     pos=0;
 625     for(;;){
 626         uint64_t startcode= find_any_startcode(bc, pos);
 627         pos= url_ftell(bc);
 628
 629         if(startcode==0){
 630             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
 631             return -1;
 632         }else if(startcode == SYNCPOINT_STARTCODE){
 633             nut->next_startcode= startcode;
 634             break;
 635         }else if(startcode != INFO_STARTCODE){
 636             continue;
 637         }
 638
 639         decode_info_header(nut);
 640     }
 641
 642     s->data_offset= pos-8;
 643
 644     if(!url_is_streamed(bc)){
 645         int64_t orig_pos= url_ftell(bc);
 646         find_and_decode_index(nut);
 647         url_fseek(bc, orig_pos, SEEK_SET);
 648     }
 649     assert(nut->next_startcode == SYNCPOINT_STARTCODE);
 650
 651     return 0;
 652 }
 653
 654 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, uint8_t *header_idx, int frame_code){
 655     AVFormatContext *s= nut->avf;
 656     ByteIOContext *bc = s->pb;
 657     StreamContext *stc;
 658     int size, flags, size_mul, pts_delta, i, reserved_count;
 659     uint64_t tmp;
 660
 661     if(url_ftell(bc) > nut->last_syncpoint_pos + nut->max_distance){
 662         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);
 663         return -1;
 664     }
 665
 666     flags          = nut->frame_code[frame_code].flags;
 667     size_mul       = nut->frame_code[frame_code].size_mul;
 668     size           = nut->frame_code[frame_code].size_lsb;
 669     *stream_id     = nut->frame_code[frame_code].stream_id;
 670     pts_delta      = nut->frame_code[frame_code].pts_delta;
 671     reserved_count = nut->frame_code[frame_code].reserved_count;
 672     *header_idx    = nut->frame_code[frame_code].header_idx;
 673
 674     if(flags & FLAG_INVALID)
 675         return -1;
 676     if(flags & FLAG_CODED)
 677         flags ^= ff_get_v(bc);
 678     if(flags & FLAG_STREAM_ID){
 679         GET_V(*stream_id, tmp < s->nb_streams)
 680     }
 681     stc= &nut->stream[*stream_id];
 682     if(flags&FLAG_CODED_PTS){
 683         int coded_pts= ff_get_v(bc);
 684 //FIXME check last_pts validity?
 685         if(coded_pts < (1<<stc->msb_pts_shift)){
 686             *pts=ff_lsb2full(stc, coded_pts);
 687         }else
 688             *pts=coded_pts - (1<<stc->msb_pts_shift);
 689     }else
 690         *pts= stc->last_pts + pts_delta;
 691     if(flags&FLAG_SIZE_MSB){
 692         size += size_mul*ff_get_v(bc);
 693     }
 694     if(flags&FLAG_MATCH_TIME)
 695         get_s(bc);
 696     if(flags&FLAG_HEADER_IDX)
 697         *header_idx= ff_get_v(bc);
 698     if(flags&FLAG_RESERVED)
 699         reserved_count= ff_get_v(bc);
 700     for(i=0; i<reserved_count; i++)
 701         ff_get_v(bc);
 702
 703     if(*header_idx >= (unsigned)nut->header_count){
 704         av_log(s, AV_LOG_ERROR, "header_idx invalid\n");
 705         return -1;
 706     }
 707     if(size > 4096)
 708         *header_idx=0;
 709     size -= nut->header_len[*header_idx];
 710
 711     if(flags&FLAG_CHECKSUM){
 712         get_be32(bc); //FIXME check this
 713     }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){
 714         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
 715         return -1;
 716     }
 717
 718     stc->last_pts= *pts;
 719     stc->last_flags= flags;
 720
 721     return size;
 722 }
 723
 724 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){
 725     AVFormatContext *s= nut->avf;
 726     ByteIOContext *bc = s->pb;
 727     int size, stream_id, discard;
 728     int64_t pts, last_IP_pts;
 729     StreamContext *stc;
 730     uint8_t header_idx;
 731
 732     size= decode_frame_header(nut, &pts, &stream_id, &header_idx, frame_code);
 733     if(size < 0)
 734         return -1;
 735
 736     stc= &nut->stream[stream_id];
 737
 738     if (stc->last_flags & FLAG_KEY)
 739         stc->skip_until_key_frame=0;
 740
 741     discard= s->streams[ stream_id ]->discard;
 742     last_IP_pts= s->streams[ stream_id ]->last_IP_pts;
 743     if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))
 744        ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)
 745        || discard >= AVDISCARD_ALL
 746        || stc->skip_until_key_frame){
 747         url_fskip(bc, size);
 748         return 1;
 749     }
 750
 751     av_new_packet(pkt, size + nut->header_len[header_idx]);
 752     memcpy(pkt->data, nut->header[header_idx], nut->header_len[header_idx]);
 753     pkt->pos= url_ftell(bc); //FIXME
 754     get_buffer(bc, pkt->data + nut->header_len[header_idx], size);
 755
 756     pkt->stream_index = stream_id;
 757     if (stc->last_flags & FLAG_KEY)
 758         pkt->flags |= PKT_FLAG_KEY;
 759     pkt->pts = pts;
 760
 761     return 0;
 762 }
 763
 764 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
 765 {
 766     NUTContext *nut = s->priv_data;
 767     ByteIOContext *bc = s->pb;
 768     int i, frame_code=0, ret, skip;
 769     int64_t ts, back_ptr;
 770
 771     for(;;){
 772         int64_t pos= url_ftell(bc);
 773         uint64_t tmp= nut->next_startcode;
 774         nut->next_startcode=0;
 775
 776         if(tmp){
 777             pos-=8;
 778         }else{
 779             frame_code = get_byte(bc);
 780             if(url_feof(bc))
 781                 return -1;
 782             if(frame_code == 'N'){
 783                 tmp= frame_code;
 784                 for(i=1; i<8; i++)
 785                     tmp = (tmp<<8) + get_byte(bc);
 786             }
 787         }
 788         switch(tmp){
 789         case MAIN_STARTCODE:
 790         case STREAM_STARTCODE:
 791         case INDEX_STARTCODE:
 792             skip= get_packetheader(nut, bc, 0, tmp);
 793             url_fseek(bc, skip, SEEK_CUR);
 794             break;
 795         case INFO_STARTCODE:
 796             if(decode_info_header(nut)<0)
 797                 goto resync;
 798             break;
 799         case SYNCPOINT_STARTCODE:
 800             if(decode_syncpoint(nut, &ts, &back_ptr)<0)
 801                 goto resync;
 802             frame_code = get_byte(bc);
 803         case 0:
 804             ret= decode_frame(nut, pkt, frame_code);
 805             if(ret==0)
 806                 return 0;
 807             else if(ret==1) //ok but discard packet
 808                 break;
 809         default:
 810 resync:
 811 av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
 812             tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);
 813             if(tmp==0)
 814                 return -1;
 815 av_log(s, AV_LOG_DEBUG, "sync\n");
 816             nut->next_startcode= tmp;
 817         }
 818     }
 819 }
 820
 821 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
 822     NUTContext *nut = s->priv_data;
 823     ByteIOContext *bc = s->pb;
 824     int64_t pos, pts, back_ptr;
 825 av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);
 826
 827     pos= *pos_arg;
 828     do{
 829         pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;
 830         if(pos < 1){
 831             assert(nut->next_startcode == 0);
 832             av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");
 833             return AV_NOPTS_VALUE;
 834         }
 835     }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);
 836     *pos_arg = pos-1;
 837     assert(nut->last_syncpoint_pos == *pos_arg);
 838
 839     av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts,back_ptr );
 840     if     (stream_index == -1) return pts;
 841     else if(stream_index == -2) return back_ptr;
 842
 843 assert(0);
 844 }
 845
 846 static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){
 847     NUTContext *nut = s->priv_data;
 848     AVStream *st= s->streams[stream_index];
 849     syncpoint_t dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};
 850     syncpoint_t nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};
 851     syncpoint_t *sp, *next_node[2]= {&nopts_sp, &nopts_sp};
 852     int64_t pos, pos2, ts;
 853     int i;
 854
 855     if(st->index_entries){
 856         int index= av_index_search_timestamp(st, pts, flags);
 857         if(index<0)
 858             return -1;
 859
 860         pos2= st->index_entries[index].pos;
 861         ts  = st->index_entries[index].timestamp;
 862     }else{
 863         av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp, next_node);
 864         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,
 865                                                     next_node[0]->ts , next_node[1]->ts);
 866         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
 867                                             next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
 868
 869         if(!(flags & AVSEEK_FLAG_BACKWARD)){
 870             dummy.pos= pos+16;
 871             next_node[1]= &nopts_sp;
 872             av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, next_node);
 873             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
 874                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
 875             if(pos2>=0)
 876                 pos= pos2;
 877             //FIXME dir but I think it does not matter
 878         }
 879         dummy.pos= pos;
 880         sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
 881
 882         assert(sp);
 883         pos2= sp->back_ptr  - 15;
 884     }
 885     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
 886     pos= find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);
 887     url_fseek(s->pb, pos, SEEK_SET);
 888     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
 889     if(pos2 > pos || pos2 + 15 < pos){
 890         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
 891     }
 892     for(i=0; i<s->nb_streams; i++)
 893         nut->stream[i].skip_until_key_frame=1;
 894
 895     return 0;
 896 }
 897
 898 static int nut_read_close(AVFormatContext *s)
 899 {
 900     NUTContext *nut = s->priv_data;
 901
 902     av_freep(&nut->time_base);
 903     av_freep(&nut->stream);
 904
 905     return 0;
 906 }
 907
 908 #ifdef CONFIG_NUT_DEMUXER
 909 AVInputFormat nut_demuxer = {
 910     "nut",
 911     NULL_IF_CONFIG_SMALL("NUT format"),
 912     sizeof(NUTContext),
 913     nut_probe,
 914     nut_read_header,
 915     nut_read_packet,
 916     nut_read_close,
 917     read_seek,
 918     .extensions = "nut",
 919 };
 920 #endif