spelling/wording cosmetics
[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 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