git.sesse.net Git - ffmpeg/blob - 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 uint64_t get_v(ByteIOContext *bc){
  31     uint64_t val = 0;
  32     int tmp;
  33
  34     do{
  35         tmp = get_byte(bc);
  36         val= (val<<7) + (tmp&127);
  37     }while(tmp&128);
  38     return val;
  39 }
  40
  41 static int get_str(ByteIOContext *bc, char *string, unsigned int maxlen){
  42     unsigned int len= get_v(bc);
  43
  44     if(len && maxlen)
  45         get_buffer(bc, string, FFMIN(len, maxlen));
  46     while(len > maxlen){
  47         get_byte(bc);
  48         len--;
  49     }
  50
  51     if(maxlen)
  52         string[FFMIN(len, maxlen-1)]= 0;
  53
  54     if(maxlen == len)
  55         return -1;
  56     else
  57         return 0;
  58 }
  59
  60 static int64_t get_s(ByteIOContext *bc){
  61     int64_t v = get_v(bc) + 1;
  62
  63     if (v&1) return -(v>>1);
  64     else     return  (v>>1);
  65 }
  66
  67 static uint64_t get_fourcc(ByteIOContext *bc){
  68     unsigned int len= get_v(bc);
  69
  70     if     (len==2) return get_le16(bc);
  71     else if(len==4) return get_le32(bc);
  72     else            return -1;
  73 }
  74
  75 #ifdef TRACE
  76 static inline uint64_t get_v_trace(ByteIOContext *bc, char *file, char *func, int line){
  77     uint64_t v= get_v(bc);
  78
  79     av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  80     return v;
  81 }
  82
  83 static inline int64_t get_s_trace(ByteIOContext *bc, char *file, char *func, int line){
  84     int64_t v= get_s(bc);
  85
  86     av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  87     return v;
  88 }
  89
  90 static inline uint64_t get_vb_trace(ByteIOContext *bc, char *file, char *func, int line){
  91     uint64_t v= get_vb(bc);
  92
  93     av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
  94     return v;
  95 }
  96 #define get_v(bc)  get_v_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  97 #define get_s(bc)  get_s_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  98 #define get_vb(bc)  get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
  99 #endif
 100
 101 static int get_packetheader(NUTContext *nut, ByteIOContext *bc, int calculate_checksum, uint64_t startcode)
 102 {
 103     int64_t size;
 104 //    start= url_ftell(bc) - 8;
 105
 106     startcode= be2me_64(startcode);
 107     startcode= av_crc04C11DB7_update(0, &startcode, 8);
 108
 109     init_checksum(bc, av_crc04C11DB7_update, startcode);
 110     size= get_v(bc);
 111     if(size > 4096)
 112         get_be32(bc);
 113     if(get_checksum(bc) && size > 4096)
 114         return -1;
 115
 116     init_checksum(bc, calculate_checksum ? av_crc04C11DB7_update : NULL, 0);
 117
 118     return size;
 119 }
 120
 121 static uint64_t find_any_startcode(ByteIOContext *bc, int64_t pos){
 122     uint64_t state=0;
 123
 124     if(pos >= 0)
 125         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
 126
 127     while(!url_feof(bc)){
 128         state= (state<<8) | get_byte(bc);
 129         if((state>>56) != 'N')
 130             continue;
 131         switch(state){
 132         case MAIN_STARTCODE:
 133         case STREAM_STARTCODE:
 134         case SYNCPOINT_STARTCODE:
 135         case INFO_STARTCODE:
 136         case INDEX_STARTCODE:
 137             return state;
 138         }
 139     }
 140
 141     return 0;
 142 }
 143
 144 /**
 145  * Find the given startcode.
 146  * @param code the startcode
 147  * @param pos the start position of the search, or -1 if the current position
 148  * @returns the position of the startcode or -1 if not found
 149  */
 150 static int64_t find_startcode(ByteIOContext *bc, uint64_t code, int64_t pos){
 151     for(;;){
 152         uint64_t startcode= find_any_startcode(bc, pos);
 153         if(startcode == code)
 154             return url_ftell(bc) - 8;
 155         else if(startcode == 0)
 156             return -1;
 157         pos=-1;
 158     }
 159 }
 160
 161 static int nut_probe(AVProbeData *p){
 162     int i;
 163     uint64_t code= 0;
 164
 165     for (i = 0; i < p->buf_size; i++) {
 166         code = (code << 8) | p->buf[i];
 167         if (code == MAIN_STARTCODE)
 168             return AVPROBE_SCORE_MAX;
 169     }
 170     return 0;
 171 }
 172
 173 #define GET_V(dst, check) \
 174     tmp= get_v(bc);\
 175     if(!(check)){\
 176         av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\
 177         return -1;\
 178     }\
 179     dst= tmp;
 180
 181 static int skip_reserved(ByteIOContext *bc, int64_t pos){
 182     pos -= url_ftell(bc);
 183     if(pos<0){
 184         url_fseek(bc, pos, SEEK_CUR);
 185         return -1;
 186     }else{
 187         while(pos--)
 188             get_byte(bc);
 189         return 0;
 190     }
 191 }
 192
 193 static int decode_main_header(NUTContext *nut){
 194     AVFormatContext *s= nut->avf;
 195     ByteIOContext *bc = &s->pb;
 196     uint64_t tmp, end;
 197     unsigned int stream_count;
 198     int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res;
 199
 200     end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);
 201     end += url_ftell(bc);
 202
 203     GET_V(tmp              , tmp >=2 && tmp <= 3)
 204     GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)
 205
 206     nut->max_distance = get_v(bc);
 207     if(nut->max_distance > 65536){
 208         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
 209         nut->max_distance= 65536;
 210     }
 211
 212     GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
 213     nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));
 214
 215     for(i=0; i<nut->time_base_count; i++){
 216         GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
 217         GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
 218         if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
 219             av_log(s, AV_LOG_ERROR, "time base invalid\n");
 220             return -1;
 221         }
 222     }
 223     tmp_pts=0;
 224     tmp_mul=1;
 225     tmp_stream=0;
 226     for(i=0; i<256;){
 227         int tmp_flags = get_v(bc);
 228         int tmp_fields= get_v(bc);
 229         if(tmp_fields>0) tmp_pts   = get_s(bc);
 230         if(tmp_fields>1) tmp_mul   = get_v(bc);
 231         if(tmp_fields>2) tmp_stream= get_v(bc);
 232         if(tmp_fields>3) tmp_size  = get_v(bc);
 233         else             tmp_size  = 0;
 234         if(tmp_fields>4) tmp_res   = get_v(bc);
 235         else             tmp_res   = 0;
 236         if(tmp_fields>5) count     = get_v(bc);
 237         else             count     = tmp_mul - tmp_size;
 238
 239         while(tmp_fields-- > 6)
 240            get_v(bc);
 241
 242         if(count == 0 || i+count > 256){
 243             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
 244             return -1;
 245         }
 246         if(tmp_stream >= stream_count){
 247             av_log(s, AV_LOG_ERROR, "illegal stream number\n");
 248             return -1;
 249         }
 250
 251         for(j=0; j<count; j++,i++){
 252             if (i == 'N') {
 253                 nut->frame_code[i].flags= FLAG_INVALID;
 254                 j--;
 255                 continue;
 256             }
 257             nut->frame_code[i].flags           = tmp_flags ;
 258             nut->frame_code[i].pts_delta       = tmp_pts   ;
 259             nut->frame_code[i].stream_id       = tmp_stream;
 260             nut->frame_code[i].size_mul        = tmp_mul   ;
 261             nut->frame_code[i].size_lsb        = tmp_size+j;
 262             nut->frame_code[i].reserved_count  = tmp_res   ;
 263         }
 264     }
 265     assert(nut->frame_code['N'].flags == FLAG_INVALID);
 266
 267     if(skip_reserved(bc, end) || get_checksum(bc)){
 268         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
 269         return -1;
 270     }
 271
 272     nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
 273     for(i=0; i<stream_count; i++){
 274         av_new_stream(s, i);
 275     }
 276
 277     return 0;
 278 }
 279
 280 static int decode_stream_header(NUTContext *nut){
 281     AVFormatContext *s= nut->avf;
 282     ByteIOContext *bc = &s->pb;
 283     StreamContext *stc;
 284     int class, stream_id;
 285     uint64_t tmp, end;
 286     AVStream *st;
 287
 288     end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);
 289     end += url_ftell(bc);
 290
 291     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
 292     stc= &nut->stream[stream_id];
 293
 294     st = s->streams[stream_id];
 295     if (!st)
 296         return AVERROR(ENOMEM);
 297
 298     class = get_v(bc);
 299     tmp = get_fourcc(bc);
 300     st->codec->codec_tag= tmp;
 301     switch(class)
 302     {
 303         case 0:
 304             st->codec->codec_type = CODEC_TYPE_VIDEO;
 305             st->codec->codec_id = codec_get_id(codec_bmp_tags, tmp);
 306             if (st->codec->codec_id == CODEC_ID_NONE)
 307                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
 308             break;
 309         case 1:
 310             st->codec->codec_type = CODEC_TYPE_AUDIO;
 311             st->codec->codec_id = codec_get_id(codec_wav_tags, tmp);
 312             if (st->codec->codec_id == CODEC_ID_NONE)
 313                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
 314             break;
 315         case 2:
 316 //            st->codec->codec_type = CODEC_TYPE_TEXT;
 317 //            break;
 318         case 3:
 319             st->codec->codec_type = CODEC_TYPE_DATA;
 320             break;
 321         default:
 322             av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
 323             return -1;
 324     }
 325     GET_V(stc->time_base_id    , tmp < nut->time_base_count);
 326     GET_V(stc->msb_pts_shift   , tmp < 16);
 327     stc->max_pts_distance= get_v(bc);
 328     GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true
 329     st->codec->has_b_frames= stc->decode_delay;
 330     get_v(bc); //stream flags
 331
 332     GET_V(st->codec->extradata_size, tmp < (1<<30));
 333     if(st->codec->extradata_size){
 334         st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
 335         get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
 336     }
 337
 338     if (st->codec->codec_type == CODEC_TYPE_VIDEO){
 339         GET_V(st->codec->width , tmp > 0)
 340         GET_V(st->codec->height, tmp > 0)
 341         st->codec->sample_aspect_ratio.num= get_v(bc);
 342         st->codec->sample_aspect_ratio.den= get_v(bc);
 343         if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
 344             av_log(s, AV_LOG_ERROR, "invalid aspect ratio\n");
 345             return -1;
 346         }
 347         get_v(bc); /* csp type */
 348     }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
 349         GET_V(st->codec->sample_rate , tmp > 0)
 350         tmp= get_v(bc); // samplerate_den
 351         if(tmp > st->codec->sample_rate){
 352             av_log(s, AV_LOG_ERROR, "Bleh, libnut muxed this ;)\n");
 353             st->codec->sample_rate= tmp;
 354         }
 355         GET_V(st->codec->channels, tmp > 0)
 356     }
 357     if(skip_reserved(bc, end) || get_checksum(bc)){
 358         av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);
 359         return -1;
 360     }
 361     stc->time_base= &nut->time_base[stc->time_base_id];
 362     av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);
 363     return 0;
 364 }
 365
 366 static int decode_info_header(NUTContext *nut){
 367     AVFormatContext *s= nut->avf;
 368     ByteIOContext *bc = &s->pb;
 369     uint64_t tmp;
 370     unsigned int stream_id_plus1, chapter_start, chapter_len, count;
 371     int chapter_id, i;
 372     int64_t value, end;
 373     char name[256], str_value[1024], type_str[256], *type= type_str;
 374
 375     end= get_packetheader(nut, bc, 1, INFO_STARTCODE);
 376     end += url_ftell(bc);
 377
 378     GET_V(stream_id_plus1, tmp <= s->nb_streams)
 379     chapter_id   = get_s(bc);
 380     chapter_start= get_v(bc);
 381     chapter_len  = get_v(bc);
 382     count        = get_v(bc);
 383     for(i=0; i<count; i++){
 384         get_str(bc, name, sizeof(name));
 385         value= get_s(bc);
 386         if(value == -1){
 387             type= "UTF-8";
 388             get_str(bc, str_value, sizeof(str_value));
 389         }else if(value == -2){
 390             get_str(bc, type, sizeof(type));
 391             get_str(bc, str_value, sizeof(str_value));
 392         }else if(value == -3){
 393             type= "s";
 394             value= get_s(bc);
 395         }else if(value == -4){
 396             type= "t";
 397             value= get_v(bc);
 398         }else if(value < -4){
 399             type= "r";
 400             get_s(bc);
 401         }else{
 402             type= "v";
 403         }
 404
 405         if(chapter_id==0 && !strcmp(type, "UTF-8")){
 406             if     (!strcmp(name, "Author"))
 407                 av_strlcpy(s->author   , str_value, sizeof(s->author));
 408             else if(!strcmp(name, "Title"))
 409                 av_strlcpy(s->title    , str_value, sizeof(s->title));
 410             else if(!strcmp(name, "Copyright"))
 411                 av_strlcpy(s->copyright, str_value, sizeof(s->copyright));
 412             else if(!strcmp(name, "Description"))
 413                 av_strlcpy(s->comment  , str_value, sizeof(s->comment));
 414         }
 415     }
 416
 417     if(skip_reserved(bc, end) || get_checksum(bc)){
 418         av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
 419         return -1;
 420     }
 421     return 0;
 422 }
 423
 424 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
 425     AVFormatContext *s= nut->avf;
 426     ByteIOContext *bc = &s->pb;
 427     int64_t end, tmp;
 428     AVRational time_base;
 429
 430     nut->last_syncpoint_pos= url_ftell(bc)-8;
 431
 432     end= get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);
 433     end += url_ftell(bc);
 434
 435     tmp= get_v(bc);
 436     *back_ptr= nut->last_syncpoint_pos - 16*get_v(bc);
 437     if(*back_ptr < 0)
 438         return -1;
 439
 440     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count], tmp);
 441
 442     if(skip_reserved(bc, end) || get_checksum(bc)){
 443         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
 444         return -1;
 445     }
 446
 447     *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;
 448     ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);
 449
 450     return 0;
 451 }
 452
 453 static int find_and_decode_index(NUTContext *nut){
 454     AVFormatContext *s= nut->avf;
 455     ByteIOContext *bc = &s->pb;
 456     uint64_t tmp, end;
 457     int i, j, syncpoint_count;
 458     int64_t filesize= url_fsize(bc);
 459     int64_t *syncpoints;
 460     int8_t *has_keyframe;
 461
 462     url_fseek(bc, filesize-12, SEEK_SET);
 463     url_fseek(bc, filesize-get_be64(bc), SEEK_SET);
 464     if(get_be64(bc) != INDEX_STARTCODE){
 465         av_log(s, AV_LOG_ERROR, "no index at the end\n");
 466         return -1;
 467     }
 468
 469     end= get_packetheader(nut, bc, 1, INDEX_STARTCODE);
 470     end += url_ftell(bc);
 471
 472     get_v(bc); //max_pts
 473     GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)
 474     syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);
 475     has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));
 476     for(i=0; i<syncpoint_count; i++){
 477         GET_V(syncpoints[i], tmp>0)
 478         if(i)
 479             syncpoints[i] += syncpoints[i-1];
 480     }
 481
 482     for(i=0; i<s->nb_streams; i++){
 483         int64_t last_pts= -1;
 484         for(j=0; j<syncpoint_count;){
 485             uint64_t x= get_v(bc);
 486             int type= x&1;
 487             int n= j;
 488             x>>=1;
 489             if(type){
 490                 int flag= x&1;
 491                 x>>=1;
 492                 if(n+x >= syncpoint_count + 1){
 493                     av_log(s, AV_LOG_ERROR, "index overflow A\n");
 494                     return -1;
 495                 }
 496                 while(x--)
 497                     has_keyframe[n++]= flag;
 498                 has_keyframe[n++]= !flag;
 499             }else{
 500                 while(x != 1){
 501                     if(n>=syncpoint_count + 1){
 502                         av_log(s, AV_LOG_ERROR, "index overflow B\n");
 503                         return -1;
 504                     }
 505                     has_keyframe[n++]= x&1;
 506                     x>>=1;
 507                 }
 508             }
 509             if(has_keyframe[0]){
 510                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
 511                 return -1;
 512             }
 513             assert(n<=syncpoint_count+1);
 514             for(; j<n; j++){
 515                 if(has_keyframe[j]){
 516                     uint64_t B, A= get_v(bc);
 517                     if(!A){
 518                         A= get_v(bc);
 519                         B= get_v(bc);
 520                         //eor_pts[j][i] = last_pts + A + B
 521                     }else
 522                         B= 0;
 523                     av_add_index_entry(
 524                         s->streams[i],
 525                         16*syncpoints[j-1],
 526                         last_pts + A,
 527                         0,
 528                         0,
 529                         AVINDEX_KEYFRAME);
 530                     last_pts += A + B;
 531                 }
 532             }
 533         }
 534     }
 535
 536     if(skip_reserved(bc, end) || get_checksum(bc)){
 537         av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");
 538         return -1;
 539     }
 540     return 0;
 541 }
 542
 543 static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
 544 {
 545     NUTContext *nut = s->priv_data;
 546     ByteIOContext *bc = &s->pb;
 547     int64_t pos;
 548     int inited_stream_count;
 549
 550     nut->avf= s;
 551
 552     /* main header */
 553     pos=0;
 554     do{
 555         pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
 556         if (pos<0+1){
 557             av_log(s, AV_LOG_ERROR, "No main startcode found.\n");
 558             return -1;
 559         }
 560     }while(decode_main_header(nut) < 0);
 561
 562     /* stream headers */
 563     pos=0;
 564     for(inited_stream_count=0; inited_stream_count < s->nb_streams;){
 565         pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
 566         if (pos<0+1){
 567             av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");
 568             return -1;
 569         }
 570         if(decode_stream_header(nut) >= 0)
 571             inited_stream_count++;
 572     }
 573
 574     /* info headers */
 575     pos=0;
 576     for(;;){
 577         uint64_t startcode= find_any_startcode(bc, pos);
 578         pos= url_ftell(bc);
 579
 580         if(startcode==0){
 581             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
 582             return -1;
 583         }else if(startcode == SYNCPOINT_STARTCODE){
 584             nut->next_startcode= startcode;
 585             break;
 586         }else if(startcode != INFO_STARTCODE){
 587             continue;
 588         }
 589
 590         decode_info_header(nut);
 591     }
 592
 593     s->data_offset= pos-8;
 594
 595     if(!url_is_streamed(bc)){
 596         int64_t orig_pos= url_ftell(bc);
 597         find_and_decode_index(nut);
 598         url_fseek(bc, orig_pos, SEEK_SET);
 599     }
 600     assert(nut->next_startcode == SYNCPOINT_STARTCODE);
 601
 602     return 0;
 603 }
 604
 605 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, int frame_code){
 606     AVFormatContext *s= nut->avf;
 607     ByteIOContext *bc = &s->pb;
 608     StreamContext *stc;
 609     int size, flags, size_mul, pts_delta, i, reserved_count;
 610     uint64_t tmp;
 611
 612     if(url_ftell(bc) > nut->last_syncpoint_pos + nut->max_distance){
 613         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);
 614         return -1;
 615     }
 616
 617     flags          = nut->frame_code[frame_code].flags;
 618     size_mul       = nut->frame_code[frame_code].size_mul;
 619     size           = nut->frame_code[frame_code].size_lsb;
 620     *stream_id     = nut->frame_code[frame_code].stream_id;
 621     pts_delta      = nut->frame_code[frame_code].pts_delta;
 622     reserved_count = nut->frame_code[frame_code].reserved_count;
 623
 624     if(flags & FLAG_INVALID)
 625         return -1;
 626     if(flags & FLAG_CODED)
 627         flags ^= get_v(bc);
 628     if(flags & FLAG_STREAM_ID){
 629         GET_V(*stream_id, tmp < s->nb_streams)
 630     }
 631     stc= &nut->stream[*stream_id];
 632     if(flags&FLAG_CODED_PTS){
 633         int coded_pts= get_v(bc);
 634 //FIXME check last_pts validity?
 635         if(coded_pts < (1<<stc->msb_pts_shift)){
 636             *pts=ff_lsb2full(stc, coded_pts);
 637         }else
 638             *pts=coded_pts - (1<<stc->msb_pts_shift);
 639     }else
 640         *pts= stc->last_pts + pts_delta;
 641     if(flags&FLAG_SIZE_MSB){
 642         size += size_mul*get_v(bc);
 643     }
 644     if(flags&FLAG_RESERVED)
 645         reserved_count= get_v(bc);
 646     for(i=0; i<reserved_count; i++)
 647         get_v(bc);
 648     if(flags&FLAG_CHECKSUM){
 649         get_be32(bc); //FIXME check this
 650     }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){
 651         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
 652         return -1;
 653     }
 654
 655     stc->last_pts= *pts;
 656     stc->last_flags= flags;
 657
 658     return size;
 659 }
 660
 661 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){
 662     AVFormatContext *s= nut->avf;
 663     ByteIOContext *bc = &s->pb;
 664     int size, stream_id, discard;
 665     int64_t pts, last_IP_pts;
 666     StreamContext *stc;
 667
 668     size= decode_frame_header(nut, &pts, &stream_id, frame_code);
 669     if(size < 0)
 670         return -1;
 671
 672     stc= &nut->stream[stream_id];
 673
 674     if (stc->last_flags & FLAG_KEY)
 675         stc->skip_until_key_frame=0;
 676
 677     discard= s->streams[ stream_id ]->discard;
 678     last_IP_pts= s->streams[ stream_id ]->last_IP_pts;
 679     if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))
 680        ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)
 681        || discard >= AVDISCARD_ALL
 682        || stc->skip_until_key_frame){
 683         url_fskip(bc, size);
 684         return 1;
 685     }
 686
 687     av_get_packet(bc, pkt, size);
 688     pkt->stream_index = stream_id;
 689     if (stc->last_flags & FLAG_KEY)
 690         pkt->flags |= PKT_FLAG_KEY;
 691     pkt->pts = pts;
 692
 693     return 0;
 694 }
 695
 696 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
 697 {
 698     NUTContext *nut = s->priv_data;
 699     ByteIOContext *bc = &s->pb;
 700     int i, frame_code=0, ret, skip;
 701     int64_t ts, back_ptr;
 702
 703     for(;;){
 704         int64_t pos= url_ftell(bc);
 705         uint64_t tmp= nut->next_startcode;
 706         nut->next_startcode=0;
 707
 708         if(tmp){
 709             pos-=8;
 710         }else{
 711             frame_code = get_byte(bc);
 712             if(url_feof(bc))
 713                 return -1;
 714             if(frame_code == 'N'){
 715                 tmp= frame_code;
 716                 for(i=1; i<8; i++)
 717                     tmp = (tmp<<8) + get_byte(bc);
 718             }
 719         }
 720         switch(tmp){
 721         case MAIN_STARTCODE:
 722         case STREAM_STARTCODE:
 723         case INDEX_STARTCODE:
 724             skip= get_packetheader(nut, bc, 0, tmp);
 725             url_fseek(bc, skip, SEEK_CUR);
 726             break;
 727         case INFO_STARTCODE:
 728             if(decode_info_header(nut)<0)
 729                 goto resync;
 730             break;
 731         case SYNCPOINT_STARTCODE:
 732             if(decode_syncpoint(nut, &ts, &back_ptr)<0)
 733                 goto resync;
 734             frame_code = get_byte(bc);
 735         case 0:
 736             ret= decode_frame(nut, pkt, frame_code);
 737             if(ret==0)
 738                 return 0;
 739             else if(ret==1) //ok but discard packet
 740                 break;
 741         default:
 742 resync:
 743 av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
 744             tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);
 745             if(tmp==0)
 746                 return -1;
 747 av_log(s, AV_LOG_DEBUG, "sync\n");
 748             nut->next_startcode= tmp;
 749         }
 750     }
 751 }
 752
 753 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
 754     NUTContext *nut = s->priv_data;
 755     ByteIOContext *bc = &s->pb;
 756     int64_t pos, pts, back_ptr;
 757 av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);
 758
 759     pos= *pos_arg;
 760 resync:
 761     do{
 762         pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;
 763         if(pos < 1){
 764             assert(nut->next_startcode == 0);
 765             av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");
 766             return AV_NOPTS_VALUE;
 767         }
 768     }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);
 769     *pos_arg = pos-1;
 770     assert(nut->last_syncpoint_pos == *pos_arg);
 771
 772     av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts,back_ptr );
 773     if     (stream_index == -1) return pts;
 774     else if(stream_index == -2) return back_ptr;
 775
 776 assert(0);
 777 }
 778
 779 static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){
 780     NUTContext *nut = s->priv_data;
 781     AVStream *st= s->streams[stream_index];
 782     syncpoint_t dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};
 783     syncpoint_t nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};
 784     syncpoint_t *sp, *next_node[2]= {&nopts_sp, &nopts_sp};
 785     int64_t pos, pos2, ts;
 786     int i;
 787
 788     if(st->index_entries){
 789         int index= av_index_search_timestamp(st, pts, flags);
 790         if(index<0)
 791             return -1;
 792
 793         pos2= st->index_entries[index].pos;
 794         ts  = st->index_entries[index].timestamp;
 795     }else{
 796         av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp, next_node);
 797         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,
 798                                                     next_node[0]->ts , next_node[1]->ts);
 799         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
 800                                             next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
 801
 802         if(!(flags & AVSEEK_FLAG_BACKWARD)){
 803             dummy.pos= pos+16;
 804             next_node[1]= &nopts_sp;
 805             av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, next_node);
 806             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
 807                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
 808             if(pos2>=0)
 809                 pos= pos2;
 810             //FIXME dir but i think it does not matter
 811         }
 812         dummy.pos= pos;
 813         sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
 814
 815         assert(sp);
 816         pos2= sp->back_ptr  - 15;
 817     }
 818     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
 819     pos= find_startcode(&s->pb, SYNCPOINT_STARTCODE, pos2);
 820     url_fseek(&s->pb, pos, SEEK_SET);
 821     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
 822     if(pos2 > pos || pos2 + 15 < pos){
 823         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
 824     }
 825     for(i=0; i<s->nb_streams; i++)
 826         nut->stream[i].skip_until_key_frame=1;
 827
 828     return 0;
 829 }
 830
 831 static int nut_read_close(AVFormatContext *s)
 832 {
 833     NUTContext *nut = s->priv_data;
 834
 835     av_freep(&nut->time_base);
 836     av_freep(&nut->stream);
 837
 838     return 0;
 839 }
 840
 841 #ifdef CONFIG_NUT_DEMUXER
 842 AVInputFormat nut_demuxer = {
 843     "nut",
 844     "nut format",
 845     sizeof(NUTContext),
 846     nut_probe,
 847     nut_read_header,
 848     nut_read_packet,
 849     nut_read_close,
 850     read_seek,
 851     .extensions = "nut",
 852 };
 853 #endif