FFmpeg
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ffmdec.c
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1 /*
2  * FFM (ffserver live feed) demuxer
3  * Copyright (c) 2001 Fabrice Bellard
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 
22 #include <stdint.h>
23 
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/intfloat.h"
26 #include "libavutil/opt.h"
27 #include "avformat.h"
28 #include "internal.h"
29 #include "ffm.h"
30 #include "avio_internal.h"
31 
33 {
34  FFMContext *ffm = s->priv_data;
35  int64_t pos, avail_size;
36  int len;
37 
38  len = ffm->packet_end - ffm->packet_ptr;
39  if (size <= len)
40  return 1;
41  pos = avio_tell(s->pb);
42  if (!ffm->write_index) {
43  if (pos == ffm->file_size)
44  return AVERROR_EOF;
45  avail_size = ffm->file_size - pos;
46  } else {
47  if (pos == ffm->write_index) {
48  /* exactly at the end of stream */
49  return AVERROR(EAGAIN);
50  } else if (pos < ffm->write_index) {
51  avail_size = ffm->write_index - pos;
52  } else {
53  avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);
54  }
55  }
56  avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;
57  if (size <= avail_size)
58  return 1;
59  else
60  return AVERROR(EAGAIN);
61 }
62 
63 static int ffm_resync(AVFormatContext *s, int state)
64 {
65  av_log(s, AV_LOG_ERROR, "resyncing\n");
66  while (state != PACKET_ID) {
67  if (avio_feof(s->pb)) {
68  av_log(s, AV_LOG_ERROR, "cannot find FFM syncword\n");
69  return -1;
70  }
71  state = (state << 8) | avio_r8(s->pb);
72  }
73  return 0;
74 }
75 
76 /* first is true if we read the frame header */
78  uint8_t *buf, int size, int header)
79 {
80  FFMContext *ffm = s->priv_data;
81  AVIOContext *pb = s->pb;
82  int len, fill_size, size1, frame_offset, id;
83 
84  size1 = size;
85  while (size > 0) {
86  redo:
87  len = ffm->packet_end - ffm->packet_ptr;
88  if (len < 0)
89  return -1;
90  if (len > size)
91  len = size;
92  if (len == 0) {
93  if (avio_tell(pb) == ffm->file_size)
94  avio_seek(pb, ffm->packet_size, SEEK_SET);
95  retry_read:
96  if (pb->buffer_size != ffm->packet_size) {
97  int64_t tell = avio_tell(pb);
99  avio_seek(pb, tell, SEEK_SET);
100  }
101  id = avio_rb16(pb); /* PACKET_ID */
102  if (id != PACKET_ID)
103  if (ffm_resync(s, id) < 0)
104  return -1;
105  fill_size = avio_rb16(pb);
106  ffm->dts = avio_rb64(pb);
107  frame_offset = avio_rb16(pb);
108  avio_read(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
109  ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
110  if (ffm->packet_end < ffm->packet || frame_offset < 0)
111  return -1;
112  /* if first packet or resynchronization packet, we must
113  handle it specifically */
114  if (ffm->first_packet || (frame_offset & 0x8000)) {
115  if (!frame_offset) {
116  /* This packet has no frame headers in it */
117  if (avio_tell(pb) >= ffm->packet_size * 3LL) {
118  avio_seek(pb, -ffm->packet_size * 2LL, SEEK_CUR);
119  goto retry_read;
120  }
121  /* This is bad, we cannot find a valid frame header */
122  return 0;
123  }
124  ffm->first_packet = 0;
125  if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE)
126  return -1;
127  ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;
128  if (!header)
129  break;
130  } else {
131  ffm->packet_ptr = ffm->packet;
132  }
133  goto redo;
134  }
135  memcpy(buf, ffm->packet_ptr, len);
136  buf += len;
137  ffm->packet_ptr += len;
138  size -= len;
139  header = 0;
140  }
141  return size1 - size;
142 }
143 
144 /* ensure that acutal seeking happens between FFM_PACKET_SIZE
145  and file_size - FFM_PACKET_SIZE */
146 static int64_t ffm_seek1(AVFormatContext *s, int64_t pos1)
147 {
148  FFMContext *ffm = s->priv_data;
149  AVIOContext *pb = s->pb;
150  int64_t pos;
151 
152  pos = FFMIN(pos1, ffm->file_size - FFM_PACKET_SIZE);
153  pos = FFMAX(pos, FFM_PACKET_SIZE);
154  av_dlog(s, "seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);
155  return avio_seek(pb, pos, SEEK_SET);
156 }
157 
158 static int64_t get_dts(AVFormatContext *s, int64_t pos)
159 {
160  AVIOContext *pb = s->pb;
161  int64_t dts;
162 
163  ffm_seek1(s, pos);
164  avio_skip(pb, 4);
165  dts = avio_rb64(pb);
166  av_dlog(s, "dts=%0.6f\n", dts / 1000000.0);
167  return dts;
168 }
169 
171 {
172  FFMContext *ffm = s->priv_data;
173  AVIOContext *pb = s->pb;
174  int64_t pts;
175  //int64_t orig_write_index = ffm->write_index;
176  int64_t pos_min, pos_max;
177  int64_t pts_start;
178  int64_t ptr = avio_tell(pb);
179 
180 
181  pos_min = 0;
182  pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
183 
184  pts_start = get_dts(s, pos_min);
185 
186  pts = get_dts(s, pos_max);
187 
188  if (pts - 100000 > pts_start)
189  goto end;
190 
192 
193  pts_start = get_dts(s, pos_min);
194 
195  pts = get_dts(s, pos_max);
196 
197  if (pts - 100000 <= pts_start) {
198  while (1) {
199  int64_t newpos;
200  int64_t newpts;
201 
202  newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
203 
204  if (newpos == pos_min)
205  break;
206 
207  newpts = get_dts(s, newpos);
208 
209  if (newpts - 100000 <= pts) {
210  pos_max = newpos;
211  pts = newpts;
212  } else {
213  pos_min = newpos;
214  }
215  }
216  ffm->write_index += pos_max;
217  }
218 
219  end:
220  avio_seek(pb, ptr, SEEK_SET);
221 }
222 
223 
225 {
226  int i;
227 
228  for (i = 0; i < s->nb_streams; i++)
229  av_freep(&s->streams[i]->codec->rc_eq);
230 
231  return 0;
232 }
233 
235 {
236  FFMContext *ffm = s->priv_data;
237  AVStream *st;
238  AVIOContext *pb = s->pb;
239  AVCodecContext *codec;
240  int ret;
241  int f_main = 0, f_cprv, f_stvi, f_stau;
242  AVCodec *enc;
243  char *buffer;
244 
245  ffm->packet_size = avio_rb32(pb);
246  if (ffm->packet_size != FFM_PACKET_SIZE) {
247  av_log(s, AV_LOG_ERROR, "Invalid packet size %d, expected size was %d\n",
249  ret = AVERROR_INVALIDDATA;
250  goto fail;
251  }
252 
253  ffm->write_index = avio_rb64(pb);
254  /* get also filesize */
255  if (pb->seekable) {
256  ffm->file_size = avio_size(pb);
257  if (ffm->write_index && 0)
259  } else {
260  ffm->file_size = (UINT64_C(1) << 63) - 1;
261  }
262 
263  while(!avio_feof(pb)) {
264  unsigned id = avio_rb32(pb);
265  unsigned size = avio_rb32(pb);
266  int64_t next = avio_tell(pb) + size;
267  char rc_eq_buf[128];
268 
269  if(!id)
270  break;
271 
272  switch(id) {
273  case MKBETAG('M', 'A', 'I', 'N'):
274  if (f_main++) {
275  ret = AVERROR(EINVAL);
276  goto fail;
277  }
278  avio_rb32(pb); /* nb_streams */
279  avio_rb32(pb); /* total bitrate */
280  break;
281  case MKBETAG('C', 'O', 'M', 'M'):
282  f_cprv = f_stvi = f_stau = 0;
283  st = avformat_new_stream(s, NULL);
284  if (!st) {
285  ret = AVERROR(ENOMEM);
286  goto fail;
287  }
288 
289  avpriv_set_pts_info(st, 64, 1, 1000000);
290 
291  codec = st->codec;
292  /* generic info */
293  codec->codec_id = avio_rb32(pb);
294  codec->codec_type = avio_r8(pb);
295  codec->bit_rate = avio_rb32(pb);
296  codec->flags = avio_rb32(pb);
297  codec->flags2 = avio_rb32(pb);
298  codec->debug = avio_rb32(pb);
299  if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
300  if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
301  return AVERROR(ENOMEM);
302  }
303  break;
304  case MKBETAG('S', 'T', 'V', 'I'):
305  if (f_stvi++) {
306  ret = AVERROR(EINVAL);
307  goto fail;
308  }
309  codec->time_base.num = avio_rb32(pb);
310  codec->time_base.den = avio_rb32(pb);
311  codec->width = avio_rb16(pb);
312  codec->height = avio_rb16(pb);
313  codec->gop_size = avio_rb16(pb);
314  codec->pix_fmt = avio_rb32(pb);
315  codec->qmin = avio_r8(pb);
316  codec->qmax = avio_r8(pb);
317  codec->max_qdiff = avio_r8(pb);
318  codec->qcompress = avio_rb16(pb) / 10000.0;
319  codec->qblur = avio_rb16(pb) / 10000.0;
320  codec->bit_rate_tolerance = avio_rb32(pb);
321  avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
322  codec->rc_eq = av_strdup(rc_eq_buf);
323  codec->rc_max_rate = avio_rb32(pb);
324  codec->rc_min_rate = avio_rb32(pb);
325  codec->rc_buffer_size = avio_rb32(pb);
326  codec->i_quant_factor = av_int2double(avio_rb64(pb));
327  codec->b_quant_factor = av_int2double(avio_rb64(pb));
328  codec->i_quant_offset = av_int2double(avio_rb64(pb));
329  codec->b_quant_offset = av_int2double(avio_rb64(pb));
330  codec->dct_algo = avio_rb32(pb);
331  codec->strict_std_compliance = avio_rb32(pb);
332  codec->max_b_frames = avio_rb32(pb);
333  codec->mpeg_quant = avio_rb32(pb);
334  codec->intra_dc_precision = avio_rb32(pb);
335  codec->me_method = avio_rb32(pb);
336  codec->mb_decision = avio_rb32(pb);
337  codec->nsse_weight = avio_rb32(pb);
338  codec->frame_skip_cmp = avio_rb32(pb);
340  codec->codec_tag = avio_rb32(pb);
341  codec->thread_count = avio_r8(pb);
342  codec->coder_type = avio_rb32(pb);
343  codec->me_cmp = avio_rb32(pb);
344  codec->me_subpel_quality = avio_rb32(pb);
345  codec->me_range = avio_rb32(pb);
346  codec->keyint_min = avio_rb32(pb);
347  codec->scenechange_threshold = avio_rb32(pb);
348  codec->b_frame_strategy = avio_rb32(pb);
349  codec->qcompress = av_int2double(avio_rb64(pb));
350  codec->qblur = av_int2double(avio_rb64(pb));
351  codec->max_qdiff = avio_rb32(pb);
352  codec->refs = avio_rb32(pb);
353  break;
354  case MKBETAG('S', 'T', 'A', 'U'):
355  if (f_stau++) {
356  ret = AVERROR(EINVAL);
357  goto fail;
358  }
359  codec->sample_rate = avio_rb32(pb);
360  codec->channels = avio_rl16(pb);
361  codec->frame_size = avio_rl16(pb);
362  break;
363  case MKBETAG('C', 'P', 'R', 'V'):
364  if (f_cprv++) {
365  ret = AVERROR(EINVAL);
366  goto fail;
367  }
368  enc = avcodec_find_encoder(codec->codec_id);
369  if (enc && enc->priv_data_size && enc->priv_class) {
372  ret = AVERROR(ENOMEM);
373  goto fail;
374  }
375  avio_get_str(pb, size, st->recommended_encoder_configuration, size + 1);
376  }
377  break;
378  case MKBETAG('S', '2', 'V', 'I'):
379  if (f_stvi++) {
380  ret = AVERROR(EINVAL);
381  goto fail;
382  }
383  buffer = av_malloc(size);
384  if (!buffer) {
385  ret = AVERROR(ENOMEM);
386  goto fail;
387  }
388  avio_get_str(pb, INT_MAX, buffer, size);
389  av_set_options_string(codec, buffer, "=", ",");
390  av_freep(&buffer);
391  break;
392  case MKBETAG('S', '2', 'A', 'U'):
393  if (f_stau++) {
394  ret = AVERROR(EINVAL);
395  goto fail;
396  }
397  buffer = av_malloc(size);
398  if (!buffer) {
399  ret = AVERROR(ENOMEM);
400  goto fail;
401  }
402  avio_get_str(pb, INT_MAX, buffer, size);
403  av_set_options_string(codec, buffer, "=", ",");
404  av_freep(&buffer);
405  break;
406  }
407  avio_seek(pb, next, SEEK_SET);
408  }
409 
410  /* get until end of block reached */
411  while ((avio_tell(pb) % ffm->packet_size) != 0)
412  avio_r8(pb);
413 
414  /* init packet demux */
415  ffm->packet_ptr = ffm->packet;
416  ffm->packet_end = ffm->packet;
417  ffm->frame_offset = 0;
418  ffm->dts = 0;
419  ffm->read_state = READ_HEADER;
420  ffm->first_packet = 1;
421  return 0;
422  fail:
423  ffm_close(s);
424  return ret;
425 }
426 
428 {
429  FFMContext *ffm = s->priv_data;
430  AVStream *st;
431  AVIOContext *pb = s->pb;
432  AVCodecContext *codec;
433  int i, nb_streams;
434  uint32_t tag;
435 
436  /* header */
437  tag = avio_rl32(pb);
438  if (tag == MKTAG('F', 'F', 'M', '2'))
439  return ffm2_read_header(s);
440  if (tag != MKTAG('F', 'F', 'M', '1'))
441  goto fail;
442  ffm->packet_size = avio_rb32(pb);
443  if (ffm->packet_size != FFM_PACKET_SIZE)
444  goto fail;
445  ffm->write_index = avio_rb64(pb);
446  /* get also filesize */
447  if (pb->seekable) {
448  ffm->file_size = avio_size(pb);
449  if (ffm->write_index && 0)
451  } else {
452  ffm->file_size = (UINT64_C(1) << 63) - 1;
453  }
454 
455  nb_streams = avio_rb32(pb);
456  avio_rb32(pb); /* total bitrate */
457  /* read each stream */
458  for(i=0;i<nb_streams;i++) {
459  char rc_eq_buf[128];
460 
461  st = avformat_new_stream(s, NULL);
462  if (!st)
463  goto fail;
464 
465  avpriv_set_pts_info(st, 64, 1, 1000000);
466 
467  codec = st->codec;
468  /* generic info */
469  codec->codec_id = avio_rb32(pb);
470  codec->codec_type = avio_r8(pb); /* codec_type */
471  codec->bit_rate = avio_rb32(pb);
472  codec->flags = avio_rb32(pb);
473  codec->flags2 = avio_rb32(pb);
474  codec->debug = avio_rb32(pb);
475  /* specific info */
476  switch(codec->codec_type) {
477  case AVMEDIA_TYPE_VIDEO:
478  codec->time_base.num = avio_rb32(pb);
479  codec->time_base.den = avio_rb32(pb);
480  codec->width = avio_rb16(pb);
481  codec->height = avio_rb16(pb);
482  codec->gop_size = avio_rb16(pb);
483  codec->pix_fmt = avio_rb32(pb);
484  codec->qmin = avio_r8(pb);
485  codec->qmax = avio_r8(pb);
486  codec->max_qdiff = avio_r8(pb);
487  codec->qcompress = avio_rb16(pb) / 10000.0;
488  codec->qblur = avio_rb16(pb) / 10000.0;
489  codec->bit_rate_tolerance = avio_rb32(pb);
490  avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
491  codec->rc_eq = av_strdup(rc_eq_buf);
492  codec->rc_max_rate = avio_rb32(pb);
493  codec->rc_min_rate = avio_rb32(pb);
494  codec->rc_buffer_size = avio_rb32(pb);
495  codec->i_quant_factor = av_int2double(avio_rb64(pb));
496  codec->b_quant_factor = av_int2double(avio_rb64(pb));
497  codec->i_quant_offset = av_int2double(avio_rb64(pb));
498  codec->b_quant_offset = av_int2double(avio_rb64(pb));
499  codec->dct_algo = avio_rb32(pb);
500  codec->strict_std_compliance = avio_rb32(pb);
501  codec->max_b_frames = avio_rb32(pb);
502  codec->mpeg_quant = avio_rb32(pb);
503  codec->intra_dc_precision = avio_rb32(pb);
504  codec->me_method = avio_rb32(pb);
505  codec->mb_decision = avio_rb32(pb);
506  codec->nsse_weight = avio_rb32(pb);
507  codec->frame_skip_cmp = avio_rb32(pb);
509  codec->codec_tag = avio_rb32(pb);
510  codec->thread_count = avio_r8(pb);
511  codec->coder_type = avio_rb32(pb);
512  codec->me_cmp = avio_rb32(pb);
513  codec->me_subpel_quality = avio_rb32(pb);
514  codec->me_range = avio_rb32(pb);
515  codec->keyint_min = avio_rb32(pb);
516  codec->scenechange_threshold = avio_rb32(pb);
517  codec->b_frame_strategy = avio_rb32(pb);
518  codec->qcompress = av_int2double(avio_rb64(pb));
519  codec->qblur = av_int2double(avio_rb64(pb));
520  codec->max_qdiff = avio_rb32(pb);
521  codec->refs = avio_rb32(pb);
522  break;
523  case AVMEDIA_TYPE_AUDIO:
524  codec->sample_rate = avio_rb32(pb);
525  codec->channels = avio_rl16(pb);
526  codec->frame_size = avio_rl16(pb);
527  break;
528  default:
529  goto fail;
530  }
531  if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
532  if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
533  return AVERROR(ENOMEM);
534  }
535  }
536 
537  /* get until end of block reached */
538  while ((avio_tell(pb) % ffm->packet_size) != 0)
539  avio_r8(pb);
540 
541  /* init packet demux */
542  ffm->packet_ptr = ffm->packet;
543  ffm->packet_end = ffm->packet;
544  ffm->frame_offset = 0;
545  ffm->dts = 0;
546  ffm->read_state = READ_HEADER;
547  ffm->first_packet = 1;
548  return 0;
549  fail:
550  ffm_close(s);
551  return -1;
552 }
553 
554 /* return < 0 if eof */
556 {
557  int size;
558  FFMContext *ffm = s->priv_data;
559  int duration, ret;
560 
561  switch(ffm->read_state) {
562  case READ_HEADER:
563  if ((ret = ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) < 0)
564  return ret;
565 
566  av_dlog(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
567  avio_tell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);
568  if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
570  return -1;
571  if (ffm->header[1] & FLAG_DTS)
572  if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)
573  return -1;
574  ffm->read_state = READ_DATA;
575  /* fall through */
576  case READ_DATA:
577  size = AV_RB24(ffm->header + 2);
578  if ((ret = ffm_is_avail_data(s, size)) < 0)
579  return ret;
580 
581  duration = AV_RB24(ffm->header + 5);
582 
583  if (av_new_packet(pkt, size) < 0) {
584  return AVERROR(ENOMEM);
585  }
586  pkt->stream_index = ffm->header[0];
587  if ((unsigned)pkt->stream_index >= s->nb_streams) {
588  av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);
589  av_free_packet(pkt);
590  ffm->read_state = READ_HEADER;
591  return -1;
592  }
593  pkt->pos = avio_tell(s->pb);
594  if (ffm->header[1] & FLAG_KEY_FRAME)
595  pkt->flags |= AV_PKT_FLAG_KEY;
596 
597  ffm->read_state = READ_HEADER;
598  if (ffm_read_data(s, pkt->data, size, 0) != size) {
599  /* bad case: desynchronized packet. we cancel all the packet loading */
600  av_free_packet(pkt);
601  return -1;
602  }
603  pkt->pts = AV_RB64(ffm->header+8);
604  if (ffm->header[1] & FLAG_DTS)
605  pkt->dts = pkt->pts - AV_RB32(ffm->header+16);
606  else
607  pkt->dts = pkt->pts;
608  pkt->duration = duration;
609  break;
610  }
611  return 0;
612 }
613 
614 /* seek to a given time in the file. The file read pointer is
615  positioned at or before pts. XXX: the following code is quite
616  approximative */
617 static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)
618 {
619  FFMContext *ffm = s->priv_data;
620  int64_t pos_min, pos_max, pos;
621  int64_t pts_min, pts_max, pts;
622  double pos1;
623 
624  av_dlog(s, "wanted_pts=%0.6f\n", wanted_pts / 1000000.0);
625  /* find the position using linear interpolation (better than
626  dichotomy in typical cases) */
627  if (ffm->write_index && ffm->write_index < ffm->file_size) {
628  if (get_dts(s, FFM_PACKET_SIZE) < wanted_pts) {
629  pos_min = FFM_PACKET_SIZE;
630  pos_max = ffm->write_index - FFM_PACKET_SIZE;
631  } else {
632  pos_min = ffm->write_index;
633  pos_max = ffm->file_size - FFM_PACKET_SIZE;
634  }
635  } else {
636  pos_min = FFM_PACKET_SIZE;
637  pos_max = ffm->file_size - FFM_PACKET_SIZE;
638  }
639  while (pos_min <= pos_max) {
640  pts_min = get_dts(s, pos_min);
641  pts_max = get_dts(s, pos_max);
642  if (pts_min > wanted_pts || pts_max <= wanted_pts) {
643  pos = pts_min > wanted_pts ? pos_min : pos_max;
644  goto found;
645  }
646  /* linear interpolation */
647  pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /
648  (double)(pts_max - pts_min);
649  pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;
650  if (pos <= pos_min)
651  pos = pos_min;
652  else if (pos >= pos_max)
653  pos = pos_max;
654  pts = get_dts(s, pos);
655  /* check if we are lucky */
656  if (pts == wanted_pts) {
657  goto found;
658  } else if (pts > wanted_pts) {
659  pos_max = pos - FFM_PACKET_SIZE;
660  } else {
661  pos_min = pos + FFM_PACKET_SIZE;
662  }
663  }
664  pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;
665 
666  found:
667  if (ffm_seek1(s, pos) < 0)
668  return -1;
669 
670  /* reset read state */
671  ffm->read_state = READ_HEADER;
672  ffm->packet_ptr = ffm->packet;
673  ffm->packet_end = ffm->packet;
674  ffm->first_packet = 1;
675 
676  return 0;
677 }
678 
679 static int ffm_probe(AVProbeData *p)
680 {
681  if (
682  p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&
683  (p->buf[3] == '1' || p->buf[3] == '2'))
684  return AVPROBE_SCORE_MAX + 1;
685  return 0;
686 }
687 
689  .name = "ffm",
690  .long_name = NULL_IF_CONFIG_SMALL("FFM (FFserver live feed)"),
691  .priv_data_size = sizeof(FFMContext),
696  .read_seek = ffm_seek,
697 };