b637bb4f4b23c401527339d1a74bea03a89e51e6
[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 #include "tree.h"
24 #include "nut.h"
25 #include "avstring.h"
26
27 #undef NDEBUG
28 #include <assert.h>
29
30 static int get_str(ByteIOContext *bc, char *string, unsigned int maxlen){
31     unsigned int len= ff_get_v(bc);
32
33     if(len && maxlen)
34         get_buffer(bc, string, FFMIN(len, maxlen));
35     while(len > maxlen){
36         get_byte(bc);
37         len--;
38     }
39
40     if(maxlen)
41         string[FFMIN(len, maxlen-1)]= 0;
42
43     if(maxlen == len)
44         return -1;
45     else
46         return 0;
47 }
48
49 static int64_t get_s(ByteIOContext *bc){
50     int64_t v = ff_get_v(bc) + 1;
51
52     if (v&1) return -(v>>1);
53     else     return  (v>>1);
54 }
55
56 static uint64_t get_fourcc(ByteIOContext *bc){
57     unsigned int len= ff_get_v(bc);
58
59     if     (len==2) return get_le16(bc);
60     else if(len==4) return get_le32(bc);
61     else            return -1;
62 }
63
64 #ifdef TRACE
65 static inline uint64_t get_v_trace(ByteIOContext *bc, char *file, char *func, int line){
66     uint64_t v= ff_get_v(bc);
67
68     av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
69     return v;
70 }
71
72 static inline int64_t get_s_trace(ByteIOContext *bc, char *file, char *func, int line){
73     int64_t v= get_s(bc);
74
75     av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
76     return v;
77 }
78
79 static inline uint64_t get_vb_trace(ByteIOContext *bc, char *file, char *func, int line){
80     uint64_t v= get_vb(bc);
81
82     av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
83     return v;
84 }
85 #define ff_get_v(bc)  get_v_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
86 #define get_s(bc)  get_s_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
87 #define get_vb(bc)  get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
88 #endif
89
90 static int get_packetheader(NUTContext *nut, ByteIOContext *bc, int calculate_checksum, uint64_t startcode)
91 {
92     int64_t size;
93 //    start= url_ftell(bc) - 8;
94
95     startcode= be2me_64(startcode);
96     startcode= ff_crc04C11DB7_update(0, &startcode, 8);
97
98     init_checksum(bc, ff_crc04C11DB7_update, startcode);
99     size= ff_get_v(bc);
100     if(size > 4096)
101         get_be32(bc);
102     if(get_checksum(bc) && size > 4096)
103         return -1;
104
105     init_checksum(bc, calculate_checksum ? ff_crc04C11DB7_update : NULL, 0);
106
107     return size;
108 }
109
110 static uint64_t find_any_startcode(ByteIOContext *bc, int64_t pos){
111     uint64_t state=0;
112
113     if(pos >= 0)
114         url_fseek(bc, pos, SEEK_SET); //note, this may fail if the stream is not seekable, but that should not matter, as in this case we simply start where we are currently
115
116     while(!url_feof(bc)){
117         state= (state<<8) | get_byte(bc);
118         if((state>>56) != 'N')
119             continue;
120         switch(state){
121         case MAIN_STARTCODE:
122         case STREAM_STARTCODE:
123         case SYNCPOINT_STARTCODE:
124         case INFO_STARTCODE:
125         case INDEX_STARTCODE:
126             return state;
127         }
128     }
129
130     return 0;
131 }
132
133 /**
134  * Find the given startcode.
135  * @param code the startcode
136  * @param pos the start position of the search, or -1 if the current position
137  * @returns the position of the startcode or -1 if not found
138  */
139 static int64_t find_startcode(ByteIOContext *bc, uint64_t code, int64_t pos){
140     for(;;){
141         uint64_t startcode= find_any_startcode(bc, pos);
142         if(startcode == code)
143             return url_ftell(bc) - 8;
144         else if(startcode == 0)
145             return -1;
146         pos=-1;
147     }
148 }
149
150 static int nut_probe(AVProbeData *p){
151     int i;
152     uint64_t code= 0;
153
154     for (i = 0; i < p->buf_size; i++) {
155         code = (code << 8) | p->buf[i];
156         if (code == MAIN_STARTCODE)
157             return AVPROBE_SCORE_MAX;
158     }
159     return 0;
160 }
161
162 #define GET_V(dst, check) \
163     tmp= ff_get_v(bc);\
164     if(!(check)){\
165         av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\
166         return -1;\
167     }\
168     dst= tmp;
169
170 static int skip_reserved(ByteIOContext *bc, int64_t pos){
171     pos -= url_ftell(bc);
172     if(pos<0){
173         url_fseek(bc, pos, SEEK_CUR);
174         return -1;
175     }else{
176         while(pos--)
177             get_byte(bc);
178         return 0;
179     }
180 }
181
182 static int decode_main_header(NUTContext *nut){
183     AVFormatContext *s= nut->avf;
184     ByteIOContext *bc = s->pb;
185     uint64_t tmp, end;
186     unsigned int stream_count;
187     int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res;
188
189     end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);
190     end += url_ftell(bc);
191
192     GET_V(tmp              , tmp >=2 && tmp <= 3)
193     GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)
194
195     nut->max_distance = ff_get_v(bc);
196     if(nut->max_distance > 65536){
197         av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
198         nut->max_distance= 65536;
199     }
200
201     GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
202     nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));
203
204     for(i=0; i<nut->time_base_count; i++){
205         GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
206         GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
207         if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
208             av_log(s, AV_LOG_ERROR, "time base invalid\n");
209             return -1;
210         }
211     }
212     tmp_pts=0;
213     tmp_mul=1;
214     tmp_stream=0;
215     for(i=0; i<256;){
216         int tmp_flags = ff_get_v(bc);
217         int tmp_fields= ff_get_v(bc);
218         if(tmp_fields>0) tmp_pts   = get_s(bc);
219         if(tmp_fields>1) tmp_mul   = ff_get_v(bc);
220         if(tmp_fields>2) tmp_stream= ff_get_v(bc);
221         if(tmp_fields>3) tmp_size  = ff_get_v(bc);
222         else             tmp_size  = 0;
223         if(tmp_fields>4) tmp_res   = ff_get_v(bc);
224         else             tmp_res   = 0;
225         if(tmp_fields>5) count     = ff_get_v(bc);
226         else             count     = tmp_mul - tmp_size;
227
228         while(tmp_fields-- > 6)
229            ff_get_v(bc);
230
231         if(count == 0 || i+count > 256){
232             av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
233             return -1;
234         }
235         if(tmp_stream >= stream_count){
236             av_log(s, AV_LOG_ERROR, "illegal stream number\n");
237             return -1;
238         }
239
240         for(j=0; j<count; j++,i++){
241             if (i == 'N') {
242                 nut->frame_code[i].flags= FLAG_INVALID;
243                 j--;
244                 continue;
245             }
246             nut->frame_code[i].flags           = tmp_flags ;
247             nut->frame_code[i].pts_delta       = tmp_pts   ;
248             nut->frame_code[i].stream_id       = tmp_stream;
249             nut->frame_code[i].size_mul        = tmp_mul   ;
250             nut->frame_code[i].size_lsb        = tmp_size+j;
251             nut->frame_code[i].reserved_count  = tmp_res   ;
252         }
253     }
254     assert(nut->frame_code['N'].flags == FLAG_INVALID);
255
256     if(skip_reserved(bc, end) || get_checksum(bc)){
257         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
258         return -1;
259     }
260
261     nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
262     for(i=0; i<stream_count; i++){
263         av_new_stream(s, i);
264     }
265
266     return 0;
267 }
268
269 static int decode_stream_header(NUTContext *nut){
270     AVFormatContext *s= nut->avf;
271     ByteIOContext *bc = s->pb;
272     StreamContext *stc;
273     int class, stream_id;
274     uint64_t tmp, end;
275     AVStream *st;
276
277     end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);
278     end += url_ftell(bc);
279
280     GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
281     stc= &nut->stream[stream_id];
282
283     st = s->streams[stream_id];
284     if (!st)
285         return AVERROR(ENOMEM);
286
287     class = ff_get_v(bc);
288     tmp = get_fourcc(bc);
289     st->codec->codec_tag= tmp;
290     switch(class)
291     {
292         case 0:
293             st->codec->codec_type = CODEC_TYPE_VIDEO;
294             st->codec->codec_id = codec_get_id(codec_bmp_tags, tmp);
295             if (st->codec->codec_id == CODEC_ID_NONE)
296                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
297             break;
298         case 1:
299             st->codec->codec_type = CODEC_TYPE_AUDIO;
300             st->codec->codec_id = codec_get_id(codec_wav_tags, tmp);
301             if (st->codec->codec_id == CODEC_ID_NONE)
302                 av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
303             break;
304         case 2:
305 //            st->codec->codec_type = CODEC_TYPE_TEXT;
306 //            break;
307         case 3:
308             st->codec->codec_type = CODEC_TYPE_DATA;
309             break;
310         default:
311             av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
312             return -1;
313     }
314     GET_V(stc->time_base_id    , tmp < nut->time_base_count);
315     GET_V(stc->msb_pts_shift   , tmp < 16);
316     stc->max_pts_distance= ff_get_v(bc);
317     GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true
318     st->codec->has_b_frames= stc->decode_delay;
319     ff_get_v(bc); //stream flags
320
321     GET_V(st->codec->extradata_size, tmp < (1<<30));
322     if(st->codec->extradata_size){
323         st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
324         get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
325     }
326
327     if (st->codec->codec_type == CODEC_TYPE_VIDEO){
328         GET_V(st->codec->width , tmp > 0)
329         GET_V(st->codec->height, tmp > 0)
330         st->codec->sample_aspect_ratio.num= ff_get_v(bc);
331         st->codec->sample_aspect_ratio.den= ff_get_v(bc);
332         if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
333             av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n", st->codec->sample_aspect_ratio.num, st->codec->sample_aspect_ratio.den);
334             return -1;
335         }
336         ff_get_v(bc); /* csp type */
337     }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
338         GET_V(st->codec->sample_rate , tmp > 0)
339         ff_get_v(bc); // samplerate_den
340         GET_V(st->codec->channels, tmp > 0)
341     }
342     if(skip_reserved(bc, end) || get_checksum(bc)){
343         av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);
344         return -1;
345     }
346     stc->time_base= &nut->time_base[stc->time_base_id];
347     av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);
348     return 0;
349 }
350
351 static int decode_info_header(NUTContext *nut){
352     AVFormatContext *s= nut->avf;
353     ByteIOContext *bc = s->pb;
354     uint64_t tmp;
355     unsigned int stream_id_plus1, chapter_start, chapter_len, count;
356     int chapter_id, i;
357     int64_t value, end;
358     char name[256], str_value[1024], type_str[256];
359     const char *type;
360
361     end= get_packetheader(nut, bc, 1, INFO_STARTCODE);
362     end += url_ftell(bc);
363
364     GET_V(stream_id_plus1, tmp <= s->nb_streams)
365     chapter_id   = get_s(bc);
366     chapter_start= ff_get_v(bc);
367     chapter_len  = ff_get_v(bc);
368     count        = ff_get_v(bc);
369     for(i=0; i<count; i++){
370         get_str(bc, name, sizeof(name));
371         value= get_s(bc);
372         if(value == -1){
373             type= "UTF-8";
374             get_str(bc, str_value, sizeof(str_value));
375         }else if(value == -2){
376             get_str(bc, type_str, sizeof(type_str));
377             type= type_str;
378             get_str(bc, str_value, sizeof(str_value));
379         }else if(value == -3){
380             type= "s";
381             value= get_s(bc);
382         }else if(value == -4){
383             type= "t";
384             value= ff_get_v(bc);
385         }else if(value < -4){
386             type= "r";
387             get_s(bc);
388         }else{
389             type= "v";
390         }
391
392         if(chapter_id==0 && !strcmp(type, "UTF-8")){
393             if     (!strcmp(name, "Author"))
394                 av_strlcpy(s->author   , str_value, sizeof(s->author));
395             else if(!strcmp(name, "Title"))
396                 av_strlcpy(s->title    , str_value, sizeof(s->title));
397             else if(!strcmp(name, "Copyright"))
398                 av_strlcpy(s->copyright, str_value, sizeof(s->copyright));
399             else if(!strcmp(name, "Description"))
400                 av_strlcpy(s->comment  , str_value, sizeof(s->comment));
401         }
402     }
403
404     if(skip_reserved(bc, end) || get_checksum(bc)){
405         av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
406         return -1;
407     }
408     return 0;
409 }
410
411 static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
412     AVFormatContext *s= nut->avf;
413     ByteIOContext *bc = s->pb;
414     int64_t end, tmp;
415
416     nut->last_syncpoint_pos= url_ftell(bc)-8;
417
418     end= get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);
419     end += url_ftell(bc);
420
421     tmp= ff_get_v(bc);
422     *back_ptr= nut->last_syncpoint_pos - 16*ff_get_v(bc);
423     if(*back_ptr < 0)
424         return -1;
425
426     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count], tmp / nut->time_base_count);
427
428     if(skip_reserved(bc, end) || get_checksum(bc)){
429         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
430         return -1;
431     }
432
433     *ts= tmp / s->nb_streams * av_q2d(nut->time_base[tmp % s->nb_streams])*AV_TIME_BASE;
434     ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts);
435
436     return 0;
437 }
438
439 static int find_and_decode_index(NUTContext *nut){
440     AVFormatContext *s= nut->avf;
441     ByteIOContext *bc = s->pb;
442     uint64_t tmp, end;
443     int i, j, syncpoint_count;
444     int64_t filesize= url_fsize(bc);
445     int64_t *syncpoints;
446     int8_t *has_keyframe;
447
448     url_fseek(bc, filesize-12, SEEK_SET);
449     url_fseek(bc, filesize-get_be64(bc), SEEK_SET);
450     if(get_be64(bc) != INDEX_STARTCODE){
451         av_log(s, AV_LOG_ERROR, "no index at the end\n");
452         return -1;
453     }
454
455     end= get_packetheader(nut, bc, 1, INDEX_STARTCODE);
456     end += url_ftell(bc);
457
458     ff_get_v(bc); //max_pts
459     GET_V(syncpoint_count, tmp < INT_MAX/8 && tmp > 0)
460     syncpoints= av_malloc(sizeof(int64_t)*syncpoint_count);
461     has_keyframe= av_malloc(sizeof(int8_t)*(syncpoint_count+1));
462     for(i=0; i<syncpoint_count; i++){
463         GET_V(syncpoints[i], tmp>0)
464         if(i)
465             syncpoints[i] += syncpoints[i-1];
466     }
467
468     for(i=0; i<s->nb_streams; i++){
469         int64_t last_pts= -1;
470         for(j=0; j<syncpoint_count;){
471             uint64_t x= ff_get_v(bc);
472             int type= x&1;
473             int n= j;
474             x>>=1;
475             if(type){
476                 int flag= x&1;
477                 x>>=1;
478                 if(n+x >= syncpoint_count + 1){
479                     av_log(s, AV_LOG_ERROR, "index overflow A\n");
480                     return -1;
481                 }
482                 while(x--)
483                     has_keyframe[n++]= flag;
484                 has_keyframe[n++]= !flag;
485             }else{
486                 while(x != 1){
487                     if(n>=syncpoint_count + 1){
488                         av_log(s, AV_LOG_ERROR, "index overflow B\n");
489                         return -1;
490                     }
491                     has_keyframe[n++]= x&1;
492                     x>>=1;
493                 }
494             }
495             if(has_keyframe[0]){
496                 av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
497                 return -1;
498             }
499             assert(n<=syncpoint_count+1);
500             for(; j<n && j<syncpoint_count; j++){
501                 if(has_keyframe[j]){
502                     uint64_t B, A= ff_get_v(bc);
503                     if(!A){
504                         A= ff_get_v(bc);
505                         B= ff_get_v(bc);
506                         //eor_pts[j][i] = last_pts + A + B
507                     }else
508                         B= 0;
509                     av_add_index_entry(
510                         s->streams[i],
511                         16*syncpoints[j-1],
512                         last_pts + A,
513                         0,
514                         0,
515                         AVINDEX_KEYFRAME);
516                     last_pts += A + B;
517                 }
518             }
519         }
520     }
521
522     if(skip_reserved(bc, end) || get_checksum(bc)){
523         av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");
524         return -1;
525     }
526     return 0;
527 }
528
529 static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
530 {
531     NUTContext *nut = s->priv_data;
532     ByteIOContext *bc = s->pb;
533     int64_t pos;
534     int initialized_stream_count;
535
536     nut->avf= s;
537
538     /* main header */
539     pos=0;
540     do{
541         pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
542         if (pos<0+1){
543             av_log(s, AV_LOG_ERROR, "No main startcode found.\n");
544             return -1;
545         }
546     }while(decode_main_header(nut) < 0);
547
548     /* stream headers */
549     pos=0;
550     for(initialized_stream_count=0; initialized_stream_count < s->nb_streams;){
551         pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
552         if (pos<0+1){
553             av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");
554             return -1;
555         }
556         if(decode_stream_header(nut) >= 0)
557             initialized_stream_count++;
558     }
559
560     /* info headers */
561     pos=0;
562     for(;;){
563         uint64_t startcode= find_any_startcode(bc, pos);
564         pos= url_ftell(bc);
565
566         if(startcode==0){
567             av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
568             return -1;
569         }else if(startcode == SYNCPOINT_STARTCODE){
570             nut->next_startcode= startcode;
571             break;
572         }else if(startcode != INFO_STARTCODE){
573             continue;
574         }
575
576         decode_info_header(nut);
577     }
578
579     s->data_offset= pos-8;
580
581     if(!url_is_streamed(bc)){
582         int64_t orig_pos= url_ftell(bc);
583         find_and_decode_index(nut);
584         url_fseek(bc, orig_pos, SEEK_SET);
585     }
586     assert(nut->next_startcode == SYNCPOINT_STARTCODE);
587
588     return 0;
589 }
590
591 static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id, int frame_code){
592     AVFormatContext *s= nut->avf;
593     ByteIOContext *bc = s->pb;
594     StreamContext *stc;
595     int size, flags, size_mul, pts_delta, i, reserved_count;
596     uint64_t tmp;
597
598     if(url_ftell(bc) > nut->last_syncpoint_pos + nut->max_distance){
599         av_log(s, AV_LOG_ERROR, "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n", url_ftell(bc), nut->last_syncpoint_pos, nut->max_distance);
600         return -1;
601     }
602
603     flags          = nut->frame_code[frame_code].flags;
604     size_mul       = nut->frame_code[frame_code].size_mul;
605     size           = nut->frame_code[frame_code].size_lsb;
606     *stream_id     = nut->frame_code[frame_code].stream_id;
607     pts_delta      = nut->frame_code[frame_code].pts_delta;
608     reserved_count = nut->frame_code[frame_code].reserved_count;
609
610     if(flags & FLAG_INVALID)
611         return -1;
612     if(flags & FLAG_CODED)
613         flags ^= ff_get_v(bc);
614     if(flags & FLAG_STREAM_ID){
615         GET_V(*stream_id, tmp < s->nb_streams)
616     }
617     stc= &nut->stream[*stream_id];
618     if(flags&FLAG_CODED_PTS){
619         int coded_pts= ff_get_v(bc);
620 //FIXME check last_pts validity?
621         if(coded_pts < (1<<stc->msb_pts_shift)){
622             *pts=ff_lsb2full(stc, coded_pts);
623         }else
624             *pts=coded_pts - (1<<stc->msb_pts_shift);
625     }else
626         *pts= stc->last_pts + pts_delta;
627     if(flags&FLAG_SIZE_MSB){
628         size += size_mul*ff_get_v(bc);
629     }
630     if(flags&FLAG_RESERVED)
631         reserved_count= ff_get_v(bc);
632     for(i=0; i<reserved_count; i++)
633         ff_get_v(bc);
634     if(flags&FLAG_CHECKSUM){
635         get_be32(bc); //FIXME check this
636     }else if(size > 2*nut->max_distance || FFABS(stc->last_pts - *pts) > stc->max_pts_distance){
637         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
638         return -1;
639     }
640
641     stc->last_pts= *pts;
642     stc->last_flags= flags;
643
644     return size;
645 }
646
647 static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code){
648     AVFormatContext *s= nut->avf;
649     ByteIOContext *bc = s->pb;
650     int size, stream_id, discard;
651     int64_t pts, last_IP_pts;
652     StreamContext *stc;
653
654     size= decode_frame_header(nut, &pts, &stream_id, frame_code);
655     if(size < 0)
656         return -1;
657
658     stc= &nut->stream[stream_id];
659
660     if (stc->last_flags & FLAG_KEY)
661         stc->skip_until_key_frame=0;
662
663     discard= s->streams[ stream_id ]->discard;
664     last_IP_pts= s->streams[ stream_id ]->last_IP_pts;
665     if(  (discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY))
666        ||(discard >= AVDISCARD_BIDIR && last_IP_pts != AV_NOPTS_VALUE && last_IP_pts > pts)
667        || discard >= AVDISCARD_ALL
668        || stc->skip_until_key_frame){
669         url_fskip(bc, size);
670         return 1;
671     }
672
673     av_get_packet(bc, pkt, size);
674     pkt->stream_index = stream_id;
675     if (stc->last_flags & FLAG_KEY)
676         pkt->flags |= PKT_FLAG_KEY;
677     pkt->pts = pts;
678
679     return 0;
680 }
681
682 static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
683 {
684     NUTContext *nut = s->priv_data;
685     ByteIOContext *bc = s->pb;
686     int i, frame_code=0, ret, skip;
687     int64_t ts, back_ptr;
688
689     for(;;){
690         int64_t pos= url_ftell(bc);
691         uint64_t tmp= nut->next_startcode;
692         nut->next_startcode=0;
693
694         if(tmp){
695             pos-=8;
696         }else{
697             frame_code = get_byte(bc);
698             if(url_feof(bc))
699                 return -1;
700             if(frame_code == 'N'){
701                 tmp= frame_code;
702                 for(i=1; i<8; i++)
703                     tmp = (tmp<<8) + get_byte(bc);
704             }
705         }
706         switch(tmp){
707         case MAIN_STARTCODE:
708         case STREAM_STARTCODE:
709         case INDEX_STARTCODE:
710             skip= get_packetheader(nut, bc, 0, tmp);
711             url_fseek(bc, skip, SEEK_CUR);
712             break;
713         case INFO_STARTCODE:
714             if(decode_info_header(nut)<0)
715                 goto resync;
716             break;
717         case SYNCPOINT_STARTCODE:
718             if(decode_syncpoint(nut, &ts, &back_ptr)<0)
719                 goto resync;
720             frame_code = get_byte(bc);
721         case 0:
722             ret= decode_frame(nut, pkt, frame_code);
723             if(ret==0)
724                 return 0;
725             else if(ret==1) //ok but discard packet
726                 break;
727         default:
728 resync:
729 av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
730             tmp= find_any_startcode(bc, nut->last_syncpoint_pos+1);
731             if(tmp==0)
732                 return -1;
733 av_log(s, AV_LOG_DEBUG, "sync\n");
734             nut->next_startcode= tmp;
735         }
736     }
737 }
738
739 static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
740     NUTContext *nut = s->priv_data;
741     ByteIOContext *bc = s->pb;
742     int64_t pos, pts, back_ptr;
743 av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n", stream_index, *pos_arg, pos_limit);
744
745     pos= *pos_arg;
746     do{
747         pos= find_startcode(bc, SYNCPOINT_STARTCODE, pos)+1;
748         if(pos < 1){
749             assert(nut->next_startcode == 0);
750             av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");
751             return AV_NOPTS_VALUE;
752         }
753     }while(decode_syncpoint(nut, &pts, &back_ptr) < 0);
754     *pos_arg = pos-1;
755     assert(nut->last_syncpoint_pos == *pos_arg);
756
757     av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts,back_ptr );
758     if     (stream_index == -1) return pts;
759     else if(stream_index == -2) return back_ptr;
760
761 assert(0);
762 }
763
764 static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags){
765     NUTContext *nut = s->priv_data;
766     AVStream *st= s->streams[stream_index];
767     syncpoint_t dummy={.ts= pts*av_q2d(st->time_base)*AV_TIME_BASE};
768     syncpoint_t nopts_sp= {.ts= AV_NOPTS_VALUE, .back_ptr= AV_NOPTS_VALUE};
769     syncpoint_t *sp, *next_node[2]= {&nopts_sp, &nopts_sp};
770     int64_t pos, pos2, ts;
771     int i;
772
773     if(st->index_entries){
774         int index= av_index_search_timestamp(st, pts, flags);
775         if(index<0)
776             return -1;
777
778         pos2= st->index_entries[index].pos;
779         ts  = st->index_entries[index].timestamp;
780     }else{
781         av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp, next_node);
782         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,
783                                                     next_node[0]->ts , next_node[1]->ts);
784         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
785                                             next_node[0]->ts , next_node[1]->ts, AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
786
787         if(!(flags & AVSEEK_FLAG_BACKWARD)){
788             dummy.pos= pos+16;
789             next_node[1]= &nopts_sp;
790             av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, next_node);
791             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
792                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
793             if(pos2>=0)
794                 pos= pos2;
795             //FIXME dir but i think it does not matter
796         }
797         dummy.pos= pos;
798         sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
799
800         assert(sp);
801         pos2= sp->back_ptr  - 15;
802     }
803     av_log(NULL, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
804     pos= find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);
805     url_fseek(s->pb, pos, SEEK_SET);
806     av_log(NULL, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
807     if(pos2 > pos || pos2 + 15 < pos){
808         av_log(NULL, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
809     }
810     for(i=0; i<s->nb_streams; i++)
811         nut->stream[i].skip_until_key_frame=1;
812
813     return 0;
814 }
815
816 static int nut_read_close(AVFormatContext *s)
817 {
818     NUTContext *nut = s->priv_data;
819
820     av_freep(&nut->time_base);
821     av_freep(&nut->stream);
822
823     return 0;
824 }
825
826 #ifdef CONFIG_NUT_DEMUXER
827 AVInputFormat nut_demuxer = {
828     "nut",
829     "nut format",
830     sizeof(NUTContext),
831     nut_probe,
832     nut_read_header,
833     nut_read_packet,
834     nut_read_close,
835     read_seek,
836     .extensions = "nut",
837 };
838 #endif