FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
gxf.c
Go to the documentation of this file.
1 /*
2  * GXF demuxer.
3  * Copyright (c) 2006 Reimar Doeffinger
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
23 #include "libavutil/common.h"
24 #include "avformat.h"
25 #include "internal.h"
26 #include "gxf.h"
27 #include "libavcodec/mpeg12data.h"
28 
30  int64_t first_field;
31  int64_t last_field;
34  int64_t track_aux_data;
35 };
36 
37 /**
38  * @brief parse gxf timecode and add it to metadata
39  */
40 static int add_timecode_metadata(AVDictionary **pm, const char *key, uint32_t timecode, int fields_per_frame)
41 {
42  char tmp[128];
43  int field = timecode & 0xff;
44  int frame = fields_per_frame ? field / fields_per_frame : field;
45  int second = (timecode >> 8) & 0xff;
46  int minute = (timecode >> 16) & 0xff;
47  int hour = (timecode >> 24) & 0x1f;
48  int drop = (timecode >> 29) & 1;
49  // bit 30: color_frame, unused
50  // ignore invalid time code
51  if (timecode >> 31)
52  return 0;
53  snprintf(tmp, sizeof(tmp), "%02d:%02d:%02d%c%02d",
54  hour, minute, second, drop ? ';' : ':', frame);
55  return av_dict_set(pm, key, tmp, 0);
56 }
57 
58 /**
59  * @brief parses a packet header, extracting type and length
60  * @param pb AVIOContext to read header from
61  * @param type detected packet type is stored here
62  * @param length detected packet length, excluding header is stored here
63  * @return 0 if header not found or contains invalid data, 1 otherwise
64  */
65 static int parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length) {
66  if (avio_rb32(pb))
67  return 0;
68  if (avio_r8(pb) != 1)
69  return 0;
70  *type = avio_r8(pb);
71  *length = avio_rb32(pb);
72  if ((*length >> 24) || *length < 16)
73  return 0;
74  *length -= 16;
75  if (avio_rb32(pb))
76  return 0;
77  if (avio_r8(pb) != 0xe1)
78  return 0;
79  if (avio_r8(pb) != 0xe2)
80  return 0;
81  return 1;
82 }
83 
84 /**
85  * @brief check if file starts with a PKT_MAP header
86  */
87 static int gxf_probe(AVProbeData *p) {
88  static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet
89  static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};
90  if (!memcmp(p->buf, startcode, sizeof(startcode)) &&
91  !memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))
92  return AVPROBE_SCORE_MAX;
93  return 0;
94 }
95 
96 /**
97  * @brief gets the stream index for the track with the specified id, creates new
98  * stream if not found
99  * @param id id of stream to find / add
100  * @param format stream format identifier
101  */
102 static int get_sindex(AVFormatContext *s, int id, int format) {
103  int i;
104  AVStream *st = NULL;
105  i = ff_find_stream_index(s, id);
106  if (i >= 0)
107  return i;
108  st = avformat_new_stream(s, NULL);
109  if (!st)
110  return AVERROR(ENOMEM);
111  st->id = id;
112  switch (format) {
113  case 3:
114  case 4:
117  break;
118  case 13:
119  case 14:
120  case 15:
121  case 16:
122  case 25:
125  break;
126  case 11:
127  case 12:
128  case 20:
131  st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
132  break;
133  case 22:
134  case 23:
137  st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
138  break;
139  case 9:
142  st->codec->channels = 1;
144  st->codec->sample_rate = 48000;
145  st->codec->bit_rate = 3 * 1 * 48000 * 8;
146  st->codec->block_align = 3 * 1;
147  st->codec->bits_per_coded_sample = 24;
148  break;
149  case 10:
152  st->codec->channels = 1;
154  st->codec->sample_rate = 48000;
155  st->codec->bit_rate = 2 * 1 * 48000 * 8;
156  st->codec->block_align = 2 * 1;
157  st->codec->bits_per_coded_sample = 16;
158  break;
159  case 17:
162  st->codec->channels = 2;
164  st->codec->sample_rate = 48000;
165  break;
166  case 26: /* AVCi50 / AVCi100 (AVC Intra) */
167  case 29: /* AVCHD */
171  break;
172  // timecode tracks:
173  case 7:
174  case 8:
175  case 24:
178  break;
179  case 30:
182  break;
183  default:
186  break;
187  }
188  return s->nb_streams - 1;
189 }
190 
191 /**
192  * @brief filters out interesting tags from material information.
193  * @param len length of tag section, will be adjusted to contain remaining bytes
194  * @param si struct to store collected information into
195  */
196 static void gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
199  while (*len >= 2) {
200  GXFMatTag tag = avio_r8(pb);
201  int tlen = avio_r8(pb);
202  *len -= 2;
203  if (tlen > *len)
204  return;
205  *len -= tlen;
206  if (tlen == 4) {
207  uint32_t value = avio_rb32(pb);
208  if (tag == MAT_FIRST_FIELD)
209  si->first_field = value;
210  else if (tag == MAT_LAST_FIELD)
211  si->last_field = value;
212  } else
213  avio_skip(pb, tlen);
214  }
215 }
216 
217 static const AVRational frame_rate_tab[] = {
218  { 60, 1},
219  {60000, 1001},
220  { 50, 1},
221  { 30, 1},
222  {30000, 1001},
223  { 25, 1},
224  { 24, 1},
225  {24000, 1001},
226  { 0, 0},
227 };
228 
229 /**
230  * @brief convert fps tag value to AVRational fps
231  * @param fps fps value from tag
232  * @return fps as AVRational, or 0 / 0 if unknown
233  */
235  if (fps < 1 || fps > 9) fps = 9;
236  return frame_rate_tab[fps - 1];
237 }
238 
239 /**
240  * @brief convert UMF attributes flags to AVRational fps
241  * @param flags UMF flags to convert
242  * @return fps as AVRational, or 0 / 0 if unknown
243  */
244 static AVRational fps_umf2avr(uint32_t flags) {
245  static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
246  {25, 1}, {30000, 1001}};
247  int idx = av_log2((flags & 0x7c0) >> 6);
248  return map[idx];
249 }
250 
251 /**
252  * @brief filters out interesting tags from track information.
253  * @param len length of tag section, will be adjusted to contain remaining bytes
254  * @param si struct to store collected information into
255  */
256 static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
257  si->frames_per_second = (AVRational){0, 0};
258  si->fields_per_frame = 0;
259  si->track_aux_data = 0x80000000;
260  while (*len >= 2) {
261  GXFTrackTag tag = avio_r8(pb);
262  int tlen = avio_r8(pb);
263  *len -= 2;
264  if (tlen > *len)
265  return;
266  *len -= tlen;
267  if (tlen == 4) {
268  uint32_t value = avio_rb32(pb);
269  if (tag == TRACK_FPS)
270  si->frames_per_second = fps_tag2avr(value);
271  else if (tag == TRACK_FPF && (value == 1 || value == 2))
272  si->fields_per_frame = value;
273  } else if (tlen == 8 && tag == TRACK_AUX)
274  si->track_aux_data = avio_rl64(pb);
275  else
276  avio_skip(pb, tlen);
277  }
278 }
279 
280 /**
281  * @brief read index from FLT packet into stream 0 av_index
282  */
283 static void gxf_read_index(AVFormatContext *s, int pkt_len) {
284  AVIOContext *pb = s->pb;
285  AVStream *st;
286  uint32_t fields_per_map = avio_rl32(pb);
287  uint32_t map_cnt = avio_rl32(pb);
288  int i;
289  pkt_len -= 8;
290  if ((s->flags & AVFMT_FLAG_IGNIDX) || !s->streams) {
291  avio_skip(pb, pkt_len);
292  return;
293  }
294  st = s->streams[0];
295  if (map_cnt > 1000) {
296  av_log(s, AV_LOG_ERROR, "too many index entries %u (%x)\n", map_cnt, map_cnt);
297  map_cnt = 1000;
298  }
299  if (pkt_len < 4 * map_cnt) {
300  av_log(s, AV_LOG_ERROR, "invalid index length\n");
301  avio_skip(pb, pkt_len);
302  return;
303  }
304  pkt_len -= 4 * map_cnt;
305  av_add_index_entry(st, 0, 0, 0, 0, 0);
306  for (i = 0; i < map_cnt; i++)
307  av_add_index_entry(st, (uint64_t)avio_rl32(pb) * 1024,
308  i * (uint64_t)fields_per_map + 1, 0, 0, 0);
309  avio_skip(pb, pkt_len);
310 }
311 
313  AVIOContext *pb = s->pb;
314  GXFPktType pkt_type;
315  int map_len;
316  int len;
317  AVRational main_timebase = {0, 0};
318  struct gxf_stream_info *si = s->priv_data;
319  int i;
320  if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
321  av_log(s, AV_LOG_ERROR, "map packet not found\n");
322  return 0;
323  }
324  map_len -= 2;
325  if (avio_r8(pb) != 0x0e0 || avio_r8(pb) != 0xff) {
326  av_log(s, AV_LOG_ERROR, "unknown version or invalid map preamble\n");
327  return 0;
328  }
329  map_len -= 2;
330  len = avio_rb16(pb); // length of material data section
331  if (len > map_len) {
332  av_log(s, AV_LOG_ERROR, "material data longer than map data\n");
333  return 0;
334  }
335  map_len -= len;
336  gxf_material_tags(pb, &len, si);
337  avio_skip(pb, len);
338  map_len -= 2;
339  len = avio_rb16(pb); // length of track description
340  if (len > map_len) {
341  av_log(s, AV_LOG_ERROR, "track description longer than map data\n");
342  return 0;
343  }
344  map_len -= len;
345  while (len > 0) {
346  int track_type, track_id, track_len;
347  AVStream *st;
348  int idx;
349  len -= 4;
350  track_type = avio_r8(pb);
351  track_id = avio_r8(pb);
352  track_len = avio_rb16(pb);
353  len -= track_len;
354  if (!(track_type & 0x80)) {
355  av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);
356  continue;
357  }
358  track_type &= 0x7f;
359  if ((track_id & 0xc0) != 0xc0) {
360  av_log(s, AV_LOG_ERROR, "invalid track id %x\n", track_id);
361  continue;
362  }
363  track_id &= 0x3f;
364  gxf_track_tags(pb, &track_len, si);
365  // check for timecode tracks
366  if (track_type == 7 || track_type == 8 || track_type == 24) {
367  add_timecode_metadata(&s->metadata, "timecode",
368  si->track_aux_data & 0xffffffff,
369  si->fields_per_frame);
370 
371  }
372  avio_skip(pb, track_len);
373 
374  idx = get_sindex(s, track_id, track_type);
375  if (idx < 0) continue;
376  st = s->streams[idx];
377  if (!main_timebase.num || !main_timebase.den) {
378  main_timebase.num = si->frames_per_second.den;
379  main_timebase.den = si->frames_per_second.num * 2;
380  }
381  st->start_time = si->first_field;
383  st->duration = si->last_field - si->first_field;
384  }
385  if (len < 0)
386  av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");
387  if (map_len)
388  avio_skip(pb, map_len);
389  if (!parse_packet_header(pb, &pkt_type, &len)) {
390  av_log(s, AV_LOG_ERROR, "sync lost in header\n");
391  return -1;
392  }
393  if (pkt_type == PKT_FLT) {
394  gxf_read_index(s, len);
395  if (!parse_packet_header(pb, &pkt_type, &len)) {
396  av_log(s, AV_LOG_ERROR, "sync lost in header\n");
397  return -1;
398  }
399  }
400  if (pkt_type == PKT_UMF) {
401  if (len >= 0x39) {
402  AVRational fps;
403  len -= 0x39;
404  avio_skip(pb, 5); // preamble
405  avio_skip(pb, 0x30); // payload description
406  fps = fps_umf2avr(avio_rl32(pb));
407  if (!main_timebase.num || !main_timebase.den) {
408  av_log(s, AV_LOG_WARNING, "No FPS track tag, using UMF fps tag."
409  " This might give wrong results.\n");
410  // this may not always be correct, but simply the best we can get
411  main_timebase.num = fps.den;
412  main_timebase.den = fps.num * 2;
413  }
414 
415  if (len >= 0x18) {
416  len -= 0x18;
417  avio_skip(pb, 0x10);
418  add_timecode_metadata(&s->metadata, "timecode_at_mark_in",
419  avio_rl32(pb), si->fields_per_frame);
420  add_timecode_metadata(&s->metadata, "timecode_at_mark_out",
421  avio_rl32(pb), si->fields_per_frame);
422  }
423  } else
424  av_log(s, AV_LOG_INFO, "UMF packet too short\n");
425  } else
426  av_log(s, AV_LOG_INFO, "UMF packet missing\n");
427  avio_skip(pb, len);
428  // set a fallback value, 60000/1001 is specified for audio-only files
429  // so use that regardless of why we do not know the video frame rate.
430  if (!main_timebase.num || !main_timebase.den)
431  main_timebase = (AVRational){1001, 60000};
432  for (i = 0; i < s->nb_streams; i++) {
433  AVStream *st = s->streams[i];
434  avpriv_set_pts_info(st, 32, main_timebase.num, main_timebase.den);
435  }
436  return 0;
437 }
438 
439 #define READ_ONE() \
440  { \
441  if (!max_interval-- || url_feof(pb)) \
442  goto out; \
443  tmp = tmp << 8 | avio_r8(pb); \
444  }
445 
446 /**
447  * @brief resync the stream on the next media packet with specified properties
448  * @param max_interval how many bytes to search for matching packet at most
449  * @param track track id the media packet must belong to, -1 for any
450  * @param timestamp minimum timestamp (== field number) the packet must have, -1 for any
451  * @return timestamp of packet found
452  */
453 static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
454  uint32_t tmp;
455  uint64_t last_pos;
456  uint64_t last_found_pos = 0;
457  int cur_track;
458  int64_t cur_timestamp = AV_NOPTS_VALUE;
459  int len;
460  AVIOContext *pb = s->pb;
462  tmp = avio_rb32(pb);
463 start:
464  while (tmp)
465  READ_ONE();
466  READ_ONE();
467  if (tmp != 1)
468  goto start;
469  last_pos = avio_tell(pb);
470  if (avio_seek(pb, -5, SEEK_CUR) < 0)
471  goto out;
472  if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
473  if (avio_seek(pb, last_pos, SEEK_SET) < 0)
474  goto out;
475  goto start;
476  }
477  avio_r8(pb);
478  cur_track = avio_r8(pb);
479  cur_timestamp = avio_rb32(pb);
480  last_found_pos = avio_tell(pb) - 16 - 6;
481  if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
482  if (avio_seek(pb, last_pos, SEEK_SET) >= 0)
483  goto start;
484  }
485 out:
486  if (last_found_pos)
487  avio_seek(pb, last_found_pos, SEEK_SET);
488  return cur_timestamp;
489 }
490 
492  AVIOContext *pb = s->pb;
493  GXFPktType pkt_type;
494  int pkt_len;
495  struct gxf_stream_info *si = s->priv_data;
496 
497  while (!pb->eof_reached) {
498  AVStream *st;
499  int track_type, track_id, ret;
500  int field_nr, field_info, skip = 0;
501  int stream_index;
502  if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
503  if (!url_feof(pb))
504  av_log(s, AV_LOG_ERROR, "sync lost\n");
505  return -1;
506  }
507  if (pkt_type == PKT_FLT) {
508  gxf_read_index(s, pkt_len);
509  continue;
510  }
511  if (pkt_type != PKT_MEDIA) {
512  avio_skip(pb, pkt_len);
513  continue;
514  }
515  if (pkt_len < 16) {
516  av_log(s, AV_LOG_ERROR, "invalid media packet length\n");
517  continue;
518  }
519  pkt_len -= 16;
520  track_type = avio_r8(pb);
521  track_id = avio_r8(pb);
522  stream_index = get_sindex(s, track_id, track_type);
523  if (stream_index < 0)
524  return stream_index;
525  st = s->streams[stream_index];
526  field_nr = avio_rb32(pb);
527  field_info = avio_rb32(pb);
528  avio_rb32(pb); // "timeline" field number
529  avio_r8(pb); // flags
530  avio_r8(pb); // reserved
531  if (st->codec->codec_id == AV_CODEC_ID_PCM_S24LE ||
533  int first = field_info >> 16;
534  int last = field_info & 0xffff; // last is exclusive
535  int bps = av_get_bits_per_sample(st->codec->codec_id)>>3;
536  if (first <= last && last*bps <= pkt_len) {
537  avio_skip(pb, first*bps);
538  skip = pkt_len - last*bps;
539  pkt_len = (last-first)*bps;
540  } else
541  av_log(s, AV_LOG_ERROR, "invalid first and last sample values\n");
542  }
543  ret = av_get_packet(pb, pkt, pkt_len);
544  if (skip)
545  avio_skip(pb, skip);
546  pkt->stream_index = stream_index;
547  pkt->dts = field_nr;
548 
549  //set duration manually for DV or else lavf misdetects the frame rate
550  if (st->codec->codec_id == AV_CODEC_ID_DVVIDEO)
551  pkt->duration = si->fields_per_frame;
552 
553  return ret;
554  }
555  return AVERROR_EOF;
556 }
557 
558 static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
559  int res = 0;
560  uint64_t pos;
561  uint64_t maxlen = 100 * 1024 * 1024;
562  AVStream *st = s->streams[0];
563  int64_t start_time = s->streams[stream_index]->start_time;
564  int64_t found;
565  int idx;
566  if (timestamp < start_time) timestamp = start_time;
567  idx = av_index_search_timestamp(st, timestamp - start_time,
569  if (idx < 0)
570  return -1;
571  pos = st->index_entries[idx].pos;
572  if (idx < st->nb_index_entries - 2)
573  maxlen = st->index_entries[idx + 2].pos - pos;
574  maxlen = FFMAX(maxlen, 200 * 1024);
575  res = avio_seek(s->pb, pos, SEEK_SET);
576  if (res < 0)
577  return res;
578  found = gxf_resync_media(s, maxlen, -1, timestamp);
579  if (FFABS(found - timestamp) > 4)
580  return -1;
581  return 0;
582 }
583 
584 static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
585  int64_t *pos, int64_t pos_limit) {
586  AVIOContext *pb = s->pb;
587  int64_t res;
588  if (avio_seek(pb, *pos, SEEK_SET) < 0)
589  return AV_NOPTS_VALUE;
590  res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
591  *pos = avio_tell(pb);
592  return res;
593 }
594 
596  .name = "gxf",
597  .long_name = NULL_IF_CONFIG_SMALL("GXF (General eXchange Format)"),
598  .priv_data_size = sizeof(struct gxf_stream_info),
599  .read_probe = gxf_probe,
600  .read_header = gxf_header,
601  .read_packet = gxf_packet,
602  .read_seek = gxf_seek,
603  .read_timestamp = gxf_read_timestamp,
604 };