get_packetheader() forgot to read the header_checksum in big packets
[ffmpeg.git] / 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
24 #include "tree.h"
25 #include "nut.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     printf("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     printf("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     printf("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)
102 {
103     int64_t start, size;
104 //    start= url_ftell(bc) - 8;
105
106     size= get_v(bc);
107     if(size > 4096)
108         get_be32(bc); //FIXME check this
109
110     init_checksum(bc, calculate_checksum ? av_crc04C11DB7_update : NULL, 0);
111
112 //    nut->packet_start[2] = start;
113 //    nut->written_packet_size= size;
114
115     return size;
116 }
117
118 static uint64_t find_any_startcode(ByteIOContext *bc, int64_t pos){
119     uint64_t state=0;
120
121     if(pos >= 0)
122         url_fseek(bc, pos, SEEK_SET); //note, this may fail if the stream isnt seekable, but that shouldnt matter, as in this case we simply start where we are currently
123
124     while(!url_feof(bc)){
125         state= (state<<8) | get_byte(bc);
126         if((state>>56) != 'N')
127             continue;
128         switch(state){
129         case MAIN_STARTCODE:
130         case STREAM_STARTCODE:
131         case SYNCPOINT_STARTCODE:
132         case INFO_STARTCODE:
133         case INDEX_STARTCODE:
134             return state;
135         }
136     }
137
138     return 0;
139 }
140
141 /**
142  * find the given startcode.
143  * @param code the startcode
144  * @param pos the start position of the search, or -1 if the current position
145  * @returns the position of the startcode or -1 if not found
146  */
147 static int64_t find_startcode(ByteIOContext *bc, uint64_t code, int64_t pos){
148     for(;;){
149         uint64_t startcode= find_any_startcode(bc, pos);
150         if(startcode == code)
151             return url_ftell(bc) - 8;
152         else if(startcode == 0)
153             return -1;
154         pos=-1;
155     }
156 }
157
158 static int64_t lsb2full(StreamContext *stream, int64_t lsb){
159     int64_t mask = (1<<stream->msb_pts_shift)-1;
160     int64_t delta= stream->last_pts - mask/2;
161     return  ((lsb - delta)&mask) + delta;
162 }
163
164 static int nut_probe(AVProbeData *p){
165     int i;
166     uint64_t code= 0;
167
168     for (i = 0; i < p->buf_size; i++) {
169         code = (code << 8) | p->buf[i];
170         if (code == MAIN_STARTCODE)
171             return AVPROBE_SCORE_MAX;
172     }
173     return 0;
174 }
175
176 #define GET_V(dst, check) \
177     tmp= get_v(bc);\
178     if(!(check)){\
179         av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\
180         return -1;\
181     }\
182     dst= tmp;
183
184 static int skip_reserved(ByteIOContext *bc, int64_t pos){
185     pos -= url_ftell(bc);
186     if(pos<0){
187         url_fseek(bc, pos, SEEK_CUR);
188         return -1;
189     }else{
190         while(pos--)
191             get_byte(bc);
192         return 0;
193     }
194 }
195
196 static int decode_main_header(NUTContext *nut){
197     AVFormatContext *s= nut->avf;
198     ByteIOContext *bc = &s->pb;
199     uint64_t tmp, end;
200     unsigned int stream_count;
201     int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res;
202
203     end= get_packetheader(nut, bc, 1);
204     end += url_ftell(bc);
205
206     GET_V(tmp              , tmp >=2 && tmp <= 3)
207     GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)
208
209     nut->max_distance = get_v(bc);
210     if(nut->max_distance > 65536){
211         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
212         nut->max_distance= 65536;
213     }
214
215     GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
216     nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));
217
218     for(i=0; i<nut->time_base_count; i++){
219         GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
220         GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
221         if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
222             av_log(s, AV_LOG_ERROR, "time base invalid\n");
223             return -1;
224         }
225     }
226     tmp_pts=0;
227     tmp_mul=1;
228     tmp_stream=0;
229     for(i=0; i<256;){
230         int tmp_flags = get_v(bc);
231         int tmp_fields= get_v(bc);
232         if(tmp_fields>0) tmp_pts   = get_s(bc);
233         if(tmp_fields>1) tmp_mul   = get_v(bc);
234         if(tmp_fields>2) tmp_stream= get_v(bc);
235         if(tmp_fields>3) tmp_size  = get_v(bc);
236         else             tmp_size  = 0;
237         if(tmp_fields>4) tmp_res   = get_v(bc);
238         else             tmp_res   = 0;
239         if(tmp_fields>5) count     = get_v(bc);
240         else             count     = tmp_mul - tmp_size;
241
242         while(tmp_fields-- > 6)
243            get_v(bc);
244
245         if(count == 0 || i+count > 256){
246             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
247             return -1;
248         }
249         if(tmp_stream >= stream_count){
250             av_log(s, AV_LOG_ERROR, "illegal stream number\n");
251             return -1;
252         }
253
254         for(j=0; j<count; j++,i++){
255             if (i == 'N') {
256                 nut->frame_code[i].flags= FLAG_INVALID;
257                 j--;
258                 continue;
259             }
260             nut->frame_code[i].flags           = tmp_flags ;
261             nut->frame_code[i].pts_delta       = tmp_pts   ;
262             nut->frame_code[i].stream_id       = tmp_stream;
263             nut->frame_code[i].size_mul        = tmp_mul   ;
264             nut->frame_code[i].size_lsb        = tmp_size+j;
265             nut->frame_code[i].reserved_count  = tmp_res   ;
266         }
267     }
268     assert(nut->frame_code['N'].flags == FLAG_INVALID);
269
270     if(skip_reserved(bc, end) || get_checksum(bc)){
271         av_log(s, AV_LOG_ERROR, "Main header checksum mismatch\n");
272         return -1;
273     }
274
275     nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
276     for(i=0; i<stream_count; i++){
277         av_new_stream(s, i);
278     }
279
280     return 0;
281 }
282
283 static int decode_stream_header(NUTContext *nut){
284     AVFormatContext *s= nut->avf;
285     ByteIOContext *bc = &s->pb;
286     StreamContext *stc;
287     int class, stream_id;
288     uint64_t tmp, end;
289     AVStream *st;
290
291     end= get_packetheader(nut, bc, 1);
292     end += url_ftell(bc);
293
294     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base.num);
295     stc= &nut->stream[stream_id];
296
297     st = s->streams[stream_id];
298     if (!st)
299         return AVERROR_NOMEM;
300
301     class = get_v(bc);
302     tmp = get_fourcc(bc);
303     st->codec->codec_tag= tmp;
304     switch(class)
305     {
306         case 0:
307             st->codec->codec_type = CODEC_TYPE_VIDEO;
308             st->codec->codec_id = codec_get_bmp_id(tmp);
309             if (st->codec->codec_id == CODEC_ID_NONE)
310                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
311             break;
312         case 1:
313             st->codec->codec_type = CODEC_TYPE_AUDIO;
314             st->codec->codec_id = codec_get_wav_id(tmp);
315             if (st->codec->codec_id == CODEC_ID_NONE)
316                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
317             break;
318         case 2:
319 //            st->codec->codec_type = CODEC_TYPE_TEXT;
320 //            break;
321         case 3:
322             st->codec->codec_type = CODEC_TYPE_DATA;
323             break;
324         default:
325             av_log(s, AV_LOG_ERROR, "Unknown stream class (%d)\n", class);
326             return -1;
327     }
328     GET_V(stc->time_base_id    , tmp < nut->time_base_count);
329     GET_V(stc->msb_pts_shift   , tmp < 16);
330     stc->max_pts_distance= get_v(bc);
331     GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if moors law is true
332     st->codec->has_b_frames= stc->decode_delay;
333     get_v(bc); //stream flags
334
335     GET_V(st->codec->extradata_size, tmp < (1<<30));
336     if(st->codec->extradata_size){
337         st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
338         get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
339     }
340
341     if (st->codec->codec_type == CODEC_TYPE_VIDEO){
342         GET_V(st->codec->width , tmp > 0)
343         GET_V(st->codec->height, tmp > 0)
344         st->codec->sample_aspect_ratio.num= get_v(bc);
345         st->codec->sample_aspect_ratio.den= get_v(bc);
346         if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
347             av_log(s, AV_LOG_ERROR, "invalid aspect ratio\n");
348             return -1;
349         }
350         get_v(bc); /* csp type */
351     }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
352         GET_V(st->codec->sample_rate , tmp > 0)
353         tmp= get_v(bc); // samplerate_den
354         if(tmp > st->codec->sample_rate){
355             av_log(s, AV_LOG_ERROR, "bleh, libnut muxed this ;)\n");
356             st->codec->sample_rate= tmp;
357         }
358         GET_V(st->codec->channels, tmp > 0)
359     }
360     if(skip_reserved(bc, end) || get_checksum(bc)){
361         av_log(s, AV_LOG_ERROR, "Stream header %d checksum mismatch\n", stream_id);
362         return -1;
363     }
364     stc->time_base= nut->time_base[stc->time_base_id];
365     av_set_pts_info(s->streams[stream_id], 63, stc->time_base.num, stc->time_base.den);
366     return 0;
367 }
368
369 static int decode_info_header(NUTContext *nut){
370     AVFormatContext *s= nut->avf;
371     ByteIOContext *bc = &s->pb;
372     uint64_t tmp;
373     unsigned int stream_id_plus1, chapter_start, chapter_len, count;
374     int chapter_id, i;
375     int64_t value, end;
376     char name[256], str_value[1024], type_str[256], *type= type_str;
377
378     end= get_packetheader(nut, bc, 1);
379     end += url_ftell(bc);
380
381     GET_V(stream_id_plus1, tmp <= s->nb_streams)
382     chapter_id   = get_s(bc);
383     chapter_start= get_v(bc);
384     chapter_len  = get_v(bc);
385     count        = get_v(bc);
386     for(i=0; i<count; i++){
387         get_str(bc, name, sizeof(name));
388         value= get_s(bc);
389         if(value == -1){
390             type= "UTF-8";
391             get_str(bc, str_value, sizeof(str_value));
392         }else if(value == -2){
393             get_str(bc, type, sizeof(type));
394             get_str(bc, str_value, sizeof(str_value));
395         }else if(value == -3){
396             type= "s";
397             value= get_s(bc);
398         }else if(value == -4){
399             type= "t";
400             value= get_v(bc);
401         }else if(value < -4){
402             type= "r";
403             get_s(bc);
404         }else{
405             type= "v";
406         }
407
408         if(chapter_id==0 && !strcmp(type, "UTF-8")){
409             if     (!strcmp(name, "Author"))
410                 pstrcpy(s->author   , sizeof(s->author)   , str_value);
411             else if(!strcmp(name, "Title"))
412                 pstrcpy(s->title    , sizeof(s->title)    , str_value);
413             else if(!strcmp(name, "Copyright"))
414                 pstrcpy(s->copyright, sizeof(s->copyright), str_value);
415             else if(!strcmp(name, "Description"))
416                 pstrcpy(s->comment  , sizeof(s->comment)  , str_value);
417         }
418     }
419
420     if(skip_reserved(bc, end) || get_checksum(bc)){
421         av_log(s, AV_LOG_ERROR, "Info header checksum mismatch\n");
422         return -1;
423     }
424     return 0;
425 }
426
427 int sp_pos_cmp(syncpoint_t *a, syncpoint_t *b){
428     return (a->pos - b->pos>>32) - (b->pos - a->pos>>32);
429 }
430
431 int sp_pts_cmp(syncpoint_t *a, syncpoint_t *b){
432     return (a->ts - b->ts>>32) - (b->ts - a->ts>>32);
433 }
434
435 static void add_sp(NUTContext *nut, int64_t pos, int64_t back_ptr, int64_t ts){
436     syncpoint_t *sp2, *sp= av_mallocz(sizeof(syncpoint_t));
437
438     sp->pos= pos;
439     sp->back_ptr= back_ptr;
440     sp->ts= ts;
441     sp2= av_tree_insert(&nut->syncpoints, sp, sp_pos_cmp);
442     if(sp2 && sp2 != sp)
443         av_free(sp);
444 }
445
446 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
447     AVFormatContext *s= nut->avf;
448     ByteIOContext *bc = &s->pb;
449     int64_t end, tmp;
450     int i;
451     AVRational time_base;
452
453     nut->last_syncpoint_pos= url_ftell(bc)-8;
454
455     end= get_packetheader(nut, bc, 1);
456     end += url_ftell(bc);
457
458     tmp= get_v(bc);
459     *back_ptr= nut->last_syncpoint_pos - 16*get_v(bc);
460     if(*back_ptr < 0)
461         return -1;
462
463     time_base= nut->time_base[tmp % nut->time_base_count];
464     for(i=0; i<s->nb_streams; i++){
465         nut->stream[i].last_pts= av_rescale_rnd(
466             tmp / nut->time_base_count,
467             time_base.num * (int64_t)nut->stream[i].time_base.den,
468             time_base.den * (int64_t)nut->stream[i].time_base.num,
469             AV_ROUND_DOWN);
470         //last_key_frame ?
471     }
472     //FIXME put this in a reset func maybe
473
474     if(skip_reserved(bc, end) || get_checksum(bc)){
475         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
476         return -1;
477     }
478
479     *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;
480     add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);
481
482     return 0;
483 }
484
485 static int find_and_decode_index(NUTContext *nut){
486     AVFormatContext *s= nut->avf;
487     ByteIOContext *bc = &s->pb;
488     uint64_t tmp, end;
489     int i, j, syncpoint_count;
490     int64_t filesize= url_fsize(bc);
491     int64_t *syncpoints;
492     int8_t *has_keyframe;
493
494     url_fseek(bc, filesize-12, SEEK_SET);
495     url_fseek(bc, filesize-get_be64(bc), SEEK_SET);
496     if(get_be64(bc) != INDEX_STARTCODE){
497         av_log(s, AV_LOG_ERROR, "no index at the end\n");
498         return -1;
499     }
500
501     end= get_packetheader(nut, bc, 1);
502     end += url_ftell(bc);
503
504     get_v(bc); //max_pts
505     GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)
506     syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);
507     has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));
508     for(i=0; i<syncpoint_count; i++){
509         GET_V(syncpoints[i], tmp>0)
510         if(i)
511             syncpoints[i] += syncpoints[i-1];
512     }
513
514     for(i=0; i<s->nb_streams; i++){
515         int64_t last_pts= -1;
516         for(j=0; j<syncpoint_count;){
517             uint64_t x= get_v(bc);
518             int type= x&1;
519             int n= j;
520             x>>=1;
521             if(type){
522                 int flag= x&1;
523                 x>>=1;
524                 if(n+x >= syncpoint_count + 1){
525                     av_log(s, AV_LOG_ERROR, "index overflow A\n");
526                     return -1;
527                 }
528                 while(x--)
529                     has_keyframe[n++]= flag;
530                 has_keyframe[n++]= !flag;
531             }else{
532                 while(x != 1){
533                     if(n>=syncpoint_count + 1){
534                         av_log(s, AV_LOG_ERROR, "index overflow B\n");
535                         return -1;
536                     }
537                     has_keyframe[n++]= x&1;
538                     x>>=1;
539                 }
540             }
541             if(has_keyframe[0]){
542                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
543                 return -1;
544             }
545             assert(n<=syncpoint_count+1);
546             for(; j<n; j++){
547                 if(has_keyframe[j]){
548                     uint64_t B, A= get_v(bc);
549                     if(!A){
550                         A= get_v(bc);
551                         B= get_v(bc);
552                         //eor_pts[j][i] = last_pts + A + B
553                     }else
554                         B= 0;
555                     av_add_index_entry(
556                         s->streams[i],
557                         16*syncpoints[j-1],
558                         last_pts + A,
559                         0,
560                         0,
561                         AVINDEX_KEYFRAME);
562                     last_pts += A + B;
563                 }
564             }
565         }
566     }
567
568     if(skip_reserved(bc, end) || get_checksum(bc)){
569         av_log(s, AV_LOG_ERROR, "Index checksum mismatch\n");
570         return -1;
571     }
572     return 0;
573 }
574
575 static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
576 {
577     NUTContext *nut = s->priv_data;
578     ByteIOContext *bc = &s->pb;
579     int64_t pos;
580     int inited_stream_count;
581
582     nut->avf= s;
583
584     /* main header */
585     pos=0;
586     do{
587         pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
588         if (pos<0+1){
589             av_log(s, AV_LOG_ERROR, "no main startcode found\n");
590             return -1;
591         }
592     }while(decode_main_header(nut) < 0);
593
594     /* stream headers */
595     pos=0;
596     for(inited_stream_count=0; inited_stream_count < s->nb_streams;){
597         pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
598         if (pos<0+1){
599             av_log(s, AV_LOG_ERROR, "not all stream headers found\n");
600             return -1;
601         }
602         if(decode_stream_header(nut) >= 0)
603             inited_stream_count++;
604     }
605
606     /* info headers */
607     pos=0;
608     for(;;){
609         uint64_t startcode= find_any_startcode(bc, pos);
610         pos= url_ftell(bc);
611
612         if(startcode==0){
613             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
614             return -1;
615         }else if(startcode == SYNCPOINT_STARTCODE){
616             nut->next_startcode= startcode;
617             break;
618         }else if(startcode != INFO_STARTCODE){
619             continue;
620         }
621
622         decode_info_header(nut);
623     }
624
625     s->data_offset= pos-8;
626
627     if(!url_is_streamed(bc)){
628         int64_t orig_pos= url_ftell(bc);
629         find_and_decode_index(nut);
630         url_fseek(bc, orig_pos, SEEK_SET);
631     }
632     assert(nut->next_startcode == SYNCPOINT_STARTCODE);
633
634     return 0;
635 }
636
637 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, int frame_code){
638     AVFormatContext *s= nut->avf;
639     ByteIOContext *bc = &s->pb;
640     StreamContext *stc;
641     int size, flags, size_mul, pts_delta, i, reserved_count;
642     uint64_t tmp;
643
644     if(url_ftell(bc) > nut->last_syncpoint_pos + nut->max_distance){
645         av_log(s, AV_LOG_ERROR, "last frame must have been damaged %Ld > %Ld + %d\n", url_ftell(bc), nut->last_syncpoint_pos, nut->max_distance);
646         return -1;
647     }
648
649     flags          = nut->frame_code[frame_code].flags;
650     size_mul       = nut->frame_code[frame_code].size_mul;
651     size           = nut->frame_code[frame_code].size_lsb;
652     *stream_id     = nut->frame_code[frame_code].stream_id;
653     pts_delta      = nut->frame_code[frame_code].pts_delta;
654     reserved_count = nut->frame_code[frame_code].reserved_count;
655
656     if(flags & FLAG_INVALID)
657         return -1;
658     if(flags & FLAG_CODED)
659         flags ^= get_v(bc);
660     if(flags & FLAG_STREAM_ID){
661         GET_V(*stream_id, tmp < s->nb_streams)
662     }
663     stc= &nut->stream[*stream_id];
664     if(flags&FLAG_CODED_PTS){
665         int coded_pts= get_v(bc);
666 //FIXME check last_pts validity?
667         if(coded_pts < (1<<stc->msb_pts_shift)){
668             *pts=lsb2full(stc, coded_pts);
669         }else
670             *pts=coded_pts - (1<<stc->msb_pts_shift);
671     }else
672         *pts= stc->last_pts + pts_delta;
673     if(flags&FLAG_SIZE_MSB){
674         size += size_mul*get_v(bc);
675     }
676     if(flags&FLAG_RESERVED)
677         reserved_count= get_v(bc);
678     for(i=0; i<reserved_count; i++)
679         get_v(bc);
680     if(flags&FLAG_CHECKSUM){
681         get_be32(bc); //FIXME check this
682     }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){
683         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
684         return -1;
685     }
686
687     stc->last_pts= *pts;
688     stc->last_flags= flags;
689
690     return size;
691 }
692
693 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){
694     AVFormatContext *s= nut->avf;
695     ByteIOContext *bc = &s->pb;
696     int size, stream_id, discard;
697     int64_t pts, last_IP_pts;
698     StreamContext *stc;
699
700     size= decode_frame_header(nut, &pts, &stream_id, frame_code);
701     if(size < 0)
702         return -1;
703
704     stc= &nut->stream[stream_id];
705
706     if (stc->last_flags & FLAG_KEY)
707         stc->skip_until_key_frame=0;
708
709     discard= s->streams[ stream_id ]->discard;
710     last_IP_pts= s->streams[ stream_id ]->last_IP_pts;
711     if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))
712        ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)
713        || discard >= AVDISCARD_ALL
714        || stc->skip_until_key_frame){
715         url_fskip(bc, size);
716         return 1;
717     }
718
719     av_get_packet(bc, pkt, size);
720     pkt->stream_index = stream_id;
721     if (stc->last_flags & FLAG_KEY)
722         pkt->flags |= PKT_FLAG_KEY;
723     pkt->pts = pts;
724
725     return 0;
726 }
727
728 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
729 {
730     NUTContext *nut = s->priv_data;
731     ByteIOContext *bc = &s->pb;
732     int i, frame_code=0, ret, skip;
733     int64_t ts, back_ptr;
734
735     for(;;){
736         int64_t pos= url_ftell(bc);
737         uint64_t tmp= nut->next_startcode;
738         nut->next_startcode=0;
739
740         if (url_feof(bc))
741             return -1;
742
743         if(tmp){
744             pos-=8;
745         }else{
746             frame_code = get_byte(bc);
747             if(frame_code == 'N'){
748                 tmp= frame_code;
749                 for(i=1; i<8; i++)
750                     tmp = (tmp<<8) + get_byte(bc);
751             }
752         }
753         switch(tmp){
754         case MAIN_STARTCODE:
755         case STREAM_STARTCODE:
756         case INDEX_STARTCODE:
757             skip= get_packetheader(nut, bc, 0);
758             url_fseek(bc, skip, SEEK_CUR);
759             break;
760         case INFO_STARTCODE:
761             if(decode_info_header(nut)<0)
762                 goto resync;
763             break;
764         case SYNCPOINT_STARTCODE:
765             if(decode_syncpoint(nut, &ts, &back_ptr)<0)
766                 goto resync;
767             frame_code = get_byte(bc);
768         case 0:
769             ret= decode_frame(nut, pkt, frame_code);
770             if(ret==0)
771                 return 0;
772             else if(ret==1) //ok but discard packet
773                 break;
774         default:
775 resync:
776 av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
777             tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);
778             if(tmp==0)
779                 return -1;
780 av_log(s, AV_LOG_DEBUG, "sync\n");
781             nut->next_startcode= tmp;
782         }
783     }
784 }
785
786 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
787     NUTContext *nut = s->priv_data;
788     ByteIOContext *bc = &s->pb;
789     int64_t pos, pts, back_ptr;
790 av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);
791
792     pos= *pos_arg;
793 resync:
794     do{
795         pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;
796         if(pos < 1){
797             assert(nut->next_startcode == 0);
798             av_log(s, AV_LOG_ERROR, "read_timestamp failed\n");
799             return AV_NOPTS_VALUE;
800         }
801     }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);
802     *pos_arg = pos-1;
803     assert(nut->last_syncpoint_pos == *pos_arg);
804
805     av_log(s, AV_LOG_DEBUG, "return %Ld %Ld\n", pts,back_ptr );
806     if     (stream_index == -1) return pts;
807     else if(stream_index == -2) return back_ptr;
808
809 assert(0);
810 }
811
812 static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){
813     NUTContext *nut = s->priv_data;
814     AVStream *st= s->streams[stream_index];
815     syncpoint_t dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};
816     syncpoint_t nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};
817     syncpoint_t *sp, *next_node[2]= {&nopts_sp, &nopts_sp};
818     int64_t pos, pos2, ts;
819     int i;
820
821     if(st->index_entries){
822         int index= av_index_search_timestamp(st, pts, flags);
823         if(index<0)
824             return -1;
825
826         pos2= st->index_entries[index].pos;
827         ts  = st->index_entries[index].timestamp;
828     }else{
829         av_tree_find(nut->syncpoints, &dummy, sp_pts_cmp, next_node);
830         av_log(s, AV_LOG_DEBUG, "%Ld-%Ld %Ld-%Ld\n", next_node[0]->pos, next_node[1]->pos,
831                                                     next_node[0]->ts , next_node[1]->ts);
832         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
833                                             next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
834
835         if(!(flags & AVSEEK_FLAG_BACKWARD)){
836             dummy.pos= pos+16;
837             next_node[1]= &nopts_sp;
838             av_tree_find(nut->syncpoints, &dummy, sp_pos_cmp, next_node);
839             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
840                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
841             if(pos2>=0)
842                 pos= pos2;
843             //FIXME dir but i think it doesnt matter
844         }
845         dummy.pos= pos;
846         sp= av_tree_find(nut->syncpoints, &dummy, sp_pos_cmp, NULL);
847
848         assert(sp);
849         pos2= sp->back_ptr  - 15;
850     }
851     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
852     pos= find_startcode(&s->pb, SYNCPOINT_STARTCODE, pos2);
853     url_fseek(&s->pb, pos, SEEK_SET);
854     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
855     if(pos2 > pos || pos2 + 15 < pos){
856         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
857     }
858     for(i=0; i<s->nb_streams; i++)
859         nut->stream[i].skip_until_key_frame=1;
860
861     return 0;
862 }
863
864 static int nut_read_close(AVFormatContext *s)
865 {
866     NUTContext *nut = s->priv_data;
867
868     av_freep(&nut->time_base);
869     av_freep(&nut->stream);
870
871     return 0;
872 }
873
874 #ifdef CONFIG_NUT_DEMUXER
875 AVInputFormat nut_demuxer = {
876     "nut",
877     "nut format",
878     sizeof(NUTContext),
879     nut_probe,
880     nut_read_header,
881     nut_read_packet,
882     nut_read_close,
883     read_seek,
884     .extensions = "nut",
885 };
886 #endif