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 "libavutil/avassert.h"
28 #include "libavutil/avstring.h"
29 #include "avformat.h"
30 #include "internal.h"
31 #include "ffm.h"
32 #include "avio_internal.h"
33 
34 static int ffm_is_avail_data(AVFormatContext *s, int size)
35 {
36  FFMContext *ffm = s->priv_data;
37  int64_t pos, avail_size;
38  int len;
39 
40  len = ffm->packet_end - ffm->packet_ptr;
41  if (size <= len)
42  return 1;
43  pos = avio_tell(s->pb);
44  if (!ffm->write_index) {
45  if (pos == ffm->file_size)
46  return AVERROR_EOF;
47  avail_size = ffm->file_size - pos;
48  } else {
49  if (pos == ffm->write_index) {
50  /* exactly at the end of stream */
51  return AVERROR(EAGAIN);
52  } else if (pos < ffm->write_index) {
53  avail_size = ffm->write_index - pos;
54  } else {
55  avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);
56  }
57  }
58  avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;
59  if (size <= avail_size)
60  return 1;
61  else
62  return AVERROR(EAGAIN);
63 }
64 
65 static int ffm_resync(AVFormatContext *s, int state)
66 {
67  av_log(s, AV_LOG_ERROR, "resyncing\n");
68  while (state != PACKET_ID) {
69  if (avio_feof(s->pb)) {
70  av_log(s, AV_LOG_ERROR, "cannot find FFM syncword\n");
71  return -1;
72  }
73  state = (state << 8) | avio_r8(s->pb);
74  }
75  return 0;
76 }
77 
78 /* first is true if we read the frame header */
79 static int ffm_read_data(AVFormatContext *s,
80  uint8_t *buf, int size, int header)
81 {
82  FFMContext *ffm = s->priv_data;
83  AVIOContext *pb = s->pb;
84  int len, fill_size, size1, frame_offset, id;
85 
86  size1 = size;
87  while (size > 0) {
88  redo:
89  len = ffm->packet_end - ffm->packet_ptr;
90  if (len < 0)
91  return -1;
92  if (len > size)
93  len = size;
94  if (len == 0) {
95  if (avio_tell(pb) == ffm->file_size)
96  avio_seek(pb, ffm->packet_size, SEEK_SET);
97  retry_read:
98  if (pb->buffer_size != ffm->packet_size) {
99  int64_t tell = avio_tell(pb);
100  ffio_set_buf_size(pb, ffm->packet_size);
101  avio_seek(pb, tell, SEEK_SET);
102  }
103  id = avio_rb16(pb); /* PACKET_ID */
104  if (id != PACKET_ID)
105  if (ffm_resync(s, id) < 0)
106  return -1;
107  fill_size = avio_rb16(pb);
108  ffm->dts = avio_rb64(pb);
109  frame_offset = avio_rb16(pb);
110  avio_read(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
111  ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
112  if (ffm->packet_end < ffm->packet || frame_offset < 0)
113  return -1;
114  /* if first packet or resynchronization packet, we must
115  handle it specifically */
116  if (ffm->first_packet || (frame_offset & 0x8000)) {
117  if (!frame_offset) {
118  /* This packet has no frame headers in it */
119  if (avio_tell(pb) >= ffm->packet_size * 3LL) {
120  avio_seek(pb, -ffm->packet_size * 2LL, SEEK_CUR);
121  goto retry_read;
122  }
123  /* This is bad, we cannot find a valid frame header */
124  return 0;
125  }
126  ffm->first_packet = 0;
127  if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE)
128  return -1;
129  ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;
130  if (!header)
131  break;
132  } else {
133  ffm->packet_ptr = ffm->packet;
134  }
135  goto redo;
136  }
137  memcpy(buf, ffm->packet_ptr, len);
138  buf += len;
139  ffm->packet_ptr += len;
140  size -= len;
141  header = 0;
142  }
143  return size1 - size;
144 }
145 
146 /* ensure that acutal seeking happens between FFM_PACKET_SIZE
147  and file_size - FFM_PACKET_SIZE */
148 static int64_t ffm_seek1(AVFormatContext *s, int64_t pos1)
149 {
150  FFMContext *ffm = s->priv_data;
151  AVIOContext *pb = s->pb;
152  int64_t pos;
153 
154  pos = FFMIN(pos1, ffm->file_size - FFM_PACKET_SIZE);
155  pos = FFMAX(pos, FFM_PACKET_SIZE);
156  av_dlog(s, "seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);
157  return avio_seek(pb, pos, SEEK_SET);
158 }
159 
160 static int64_t get_dts(AVFormatContext *s, int64_t pos)
161 {
162  AVIOContext *pb = s->pb;
163  int64_t dts;
164 
165  ffm_seek1(s, pos);
166  avio_skip(pb, 4);
167  dts = avio_rb64(pb);
168  av_dlog(s, "dts=%0.6f\n", dts / 1000000.0);
169  return dts;
170 }
171 
172 static void adjust_write_index(AVFormatContext *s)
173 {
174  FFMContext *ffm = s->priv_data;
175  AVIOContext *pb = s->pb;
176  int64_t pts;
177  //int64_t orig_write_index = ffm->write_index;
178  int64_t pos_min, pos_max;
179  int64_t pts_start;
180  int64_t ptr = avio_tell(pb);
181 
182 
183  pos_min = 0;
184  pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
185 
186  pts_start = get_dts(s, pos_min);
187 
188  pts = get_dts(s, pos_max);
189 
190  if (pts - 100000 > pts_start)
191  goto end;
192 
193  ffm->write_index = FFM_PACKET_SIZE;
194 
195  pts_start = get_dts(s, pos_min);
196 
197  pts = get_dts(s, pos_max);
198 
199  if (pts - 100000 <= pts_start) {
200  while (1) {
201  int64_t newpos;
202  int64_t newpts;
203 
204  newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
205 
206  if (newpos == pos_min)
207  break;
208 
209  newpts = get_dts(s, newpos);
210 
211  if (newpts - 100000 <= pts) {
212  pos_max = newpos;
213  pts = newpts;
214  } else {
215  pos_min = newpos;
216  }
217  }
218  ffm->write_index += pos_max;
219  }
220 
221  end:
222  avio_seek(pb, ptr, SEEK_SET);
223 }
224 
225 
226 static int ffm_close(AVFormatContext *s)
227 {
228  int i;
229 
230  for (i = 0; i < s->nb_streams; i++)
231  av_freep(&s->streams[i]->codec->rc_eq);
232 
233  return 0;
234 }
235 
236 static int ffm_append_recommended_configuration(AVStream *st, char **conf)
237 {
238  int ret;
239  size_t newsize;
240  av_assert0(conf && st);
241  if (!*conf)
242  return 0;
243  if (!st->recommended_encoder_configuration) {
244  st->recommended_encoder_configuration = *conf;
245  *conf = 0;
246  return 0;
247  }
248  newsize = strlen(*conf) + strlen(st->recommended_encoder_configuration) + 2;
249  if ((ret = av_reallocp(&st->recommended_encoder_configuration, newsize)) < 0)
250  return ret;
251  av_strlcat(st->recommended_encoder_configuration, ",", newsize);
252  av_strlcat(st->recommended_encoder_configuration, *conf, newsize);
253  av_freep(conf);
254  return 0;
255 }
256 
257 static int ffm2_read_header(AVFormatContext *s)
258 {
259  FFMContext *ffm = s->priv_data;
260  AVStream *st;
261  AVIOContext *pb = s->pb;
262  AVCodecContext *codec;
263  int ret;
264  int f_main = 0, f_cprv, f_stvi, f_stau;
265  AVCodec *enc;
266  char *buffer;
267 
268  ffm->packet_size = avio_rb32(pb);
269  if (ffm->packet_size != FFM_PACKET_SIZE) {
270  av_log(s, AV_LOG_ERROR, "Invalid packet size %d, expected size was %d\n",
271  ffm->packet_size, FFM_PACKET_SIZE);
272  ret = AVERROR_INVALIDDATA;
273  goto fail;
274  }
275 
276  ffm->write_index = avio_rb64(pb);
277  /* get also filesize */
278  if (pb->seekable) {
279  ffm->file_size = avio_size(pb);
280  if (ffm->write_index && 0)
281  adjust_write_index(s);
282  } else {
283  ffm->file_size = (UINT64_C(1) << 63) - 1;
284  }
285 
286  while(!avio_feof(pb)) {
287  unsigned id = avio_rb32(pb);
288  unsigned size = avio_rb32(pb);
289  int64_t next = avio_tell(pb) + size;
290  char rc_eq_buf[128];
291 
292  if(!id)
293  break;
294 
295  switch(id) {
296  case MKBETAG('M', 'A', 'I', 'N'):
297  if (f_main++) {
298  ret = AVERROR(EINVAL);
299  goto fail;
300  }
301  avio_rb32(pb); /* nb_streams */
302  avio_rb32(pb); /* total bitrate */
303  break;
304  case MKBETAG('C', 'O', 'M', 'M'):
305  f_cprv = f_stvi = f_stau = 0;
306  st = avformat_new_stream(s, NULL);
307  if (!st) {
308  ret = AVERROR(ENOMEM);
309  goto fail;
310  }
311 
312  avpriv_set_pts_info(st, 64, 1, 1000000);
313 
314  codec = st->codec;
315  /* generic info */
316  codec->codec_id = avio_rb32(pb);
317  codec->codec_type = avio_r8(pb);
318  codec->bit_rate = avio_rb32(pb);
319  codec->flags = avio_rb32(pb);
320  codec->flags2 = avio_rb32(pb);
321  codec->debug = avio_rb32(pb);
322  if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
323  if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
324  return AVERROR(ENOMEM);
325  }
326  break;
327  case MKBETAG('S', 'T', 'V', 'I'):
328  if (f_stvi++) {
329  ret = AVERROR(EINVAL);
330  goto fail;
331  }
332  codec->time_base.num = avio_rb32(pb);
333  codec->time_base.den = avio_rb32(pb);
334  codec->width = avio_rb16(pb);
335  codec->height = avio_rb16(pb);
336  codec->gop_size = avio_rb16(pb);
337  codec->pix_fmt = avio_rb32(pb);
338  codec->qmin = avio_r8(pb);
339  codec->qmax = avio_r8(pb);
340  codec->max_qdiff = avio_r8(pb);
341  codec->qcompress = avio_rb16(pb) / 10000.0;
342  codec->qblur = avio_rb16(pb) / 10000.0;
343  codec->bit_rate_tolerance = avio_rb32(pb);
344  avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
345  codec->rc_eq = av_strdup(rc_eq_buf);
346  codec->rc_max_rate = avio_rb32(pb);
347  codec->rc_min_rate = avio_rb32(pb);
348  codec->rc_buffer_size = avio_rb32(pb);
349  codec->i_quant_factor = av_int2double(avio_rb64(pb));
350  codec->b_quant_factor = av_int2double(avio_rb64(pb));
351  codec->i_quant_offset = av_int2double(avio_rb64(pb));
352  codec->b_quant_offset = av_int2double(avio_rb64(pb));
353  codec->dct_algo = avio_rb32(pb);
354  codec->strict_std_compliance = avio_rb32(pb);
355  codec->max_b_frames = avio_rb32(pb);
356  codec->mpeg_quant = avio_rb32(pb);
357  codec->intra_dc_precision = avio_rb32(pb);
358  codec->me_method = avio_rb32(pb);
359  codec->mb_decision = avio_rb32(pb);
360  codec->nsse_weight = avio_rb32(pb);
361  codec->frame_skip_cmp = avio_rb32(pb);
362  codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));
363  codec->codec_tag = avio_rb32(pb);
364  codec->thread_count = avio_r8(pb);
365  codec->coder_type = avio_rb32(pb);
366  codec->me_cmp = avio_rb32(pb);
367  codec->me_subpel_quality = avio_rb32(pb);
368  codec->me_range = avio_rb32(pb);
369  codec->keyint_min = avio_rb32(pb);
370  codec->scenechange_threshold = avio_rb32(pb);
371  codec->b_frame_strategy = avio_rb32(pb);
372  codec->qcompress = av_int2double(avio_rb64(pb));
373  codec->qblur = av_int2double(avio_rb64(pb));
374  codec->max_qdiff = avio_rb32(pb);
375  codec->refs = avio_rb32(pb);
376  break;
377  case MKBETAG('S', 'T', 'A', 'U'):
378  if (f_stau++) {
379  ret = AVERROR(EINVAL);
380  goto fail;
381  }
382  codec->sample_rate = avio_rb32(pb);
383  codec->channels = avio_rl16(pb);
384  codec->frame_size = avio_rl16(pb);
385  break;
386  case MKBETAG('C', 'P', 'R', 'V'):
387  if (f_cprv++) {
388  ret = AVERROR(EINVAL);
389  goto fail;
390  }
391  enc = avcodec_find_encoder(codec->codec_id);
392  if (enc && enc->priv_data_size && enc->priv_class) {
393  buffer = av_malloc(size + 1);
394  if (!buffer) {
395  ret = AVERROR(ENOMEM);
396  goto fail;
397  }
398  avio_get_str(pb, size, buffer, size + 1);
399  if ((ret = ffm_append_recommended_configuration(st, &buffer)) < 0)
400  goto fail;
401  }
402  break;
403  case MKBETAG('S', '2', 'V', 'I'):
404  if (f_stvi++) {
405  ret = AVERROR(EINVAL);
406  goto fail;
407  }
408  buffer = av_malloc(size);
409  if (!buffer) {
410  ret = AVERROR(ENOMEM);
411  goto fail;
412  }
413  avio_get_str(pb, INT_MAX, buffer, size);
414  av_set_options_string(codec, buffer, "=", ",");
415  if ((ret = ffm_append_recommended_configuration(st, &buffer)) < 0)
416  goto fail;
417  break;
418  case MKBETAG('S', '2', 'A', 'U'):
419  if (f_stau++) {
420  ret = AVERROR(EINVAL);
421  goto fail;
422  }
423  buffer = av_malloc(size);
424  if (!buffer) {
425  ret = AVERROR(ENOMEM);
426  goto fail;
427  }
428  avio_get_str(pb, INT_MAX, buffer, size);
429  av_set_options_string(codec, buffer, "=", ",");
430  ffm_append_recommended_configuration(st, &buffer);
431  break;
432  }
433  avio_seek(pb, next, SEEK_SET);
434  }
435 
436  /* get until end of block reached */
437  while ((avio_tell(pb) % ffm->packet_size) != 0)
438  avio_r8(pb);
439 
440  /* init packet demux */
441  ffm->packet_ptr = ffm->packet;
442  ffm->packet_end = ffm->packet;
443  ffm->frame_offset = 0;
444  ffm->dts = 0;
445  ffm->read_state = READ_HEADER;
446  ffm->first_packet = 1;
447  return 0;
448  fail:
449  ffm_close(s);
450  return ret;
451 }
452 
453 static int ffm_read_header(AVFormatContext *s)
454 {
455  FFMContext *ffm = s->priv_data;
456  AVStream *st;
457  AVIOContext *pb = s->pb;
458  AVCodecContext *codec;
459  int i, nb_streams;
460  uint32_t tag;
461 
462  /* header */
463  tag = avio_rl32(pb);
464  if (tag == MKTAG('F', 'F', 'M', '2'))
465  return ffm2_read_header(s);
466  if (tag != MKTAG('F', 'F', 'M', '1'))
467  goto fail;
468  ffm->packet_size = avio_rb32(pb);
469  if (ffm->packet_size != FFM_PACKET_SIZE)
470  goto fail;
471  ffm->write_index = avio_rb64(pb);
472  /* get also filesize */
473  if (pb->seekable) {
474  ffm->file_size = avio_size(pb);
475  if (ffm->write_index && 0)
476  adjust_write_index(s);
477  } else {
478  ffm->file_size = (UINT64_C(1) << 63) - 1;
479  }
480 
481  nb_streams = avio_rb32(pb);
482  avio_rb32(pb); /* total bitrate */
483  /* read each stream */
484  for(i=0;i<nb_streams;i++) {
485  char rc_eq_buf[128];
486 
487  st = avformat_new_stream(s, NULL);
488  if (!st)
489  goto fail;
490 
491  avpriv_set_pts_info(st, 64, 1, 1000000);
492 
493  codec = st->codec;
494  /* generic info */
495  codec->codec_id = avio_rb32(pb);
496  codec->codec_type = avio_r8(pb); /* codec_type */
497  codec->bit_rate = avio_rb32(pb);
498  codec->flags = avio_rb32(pb);
499  codec->flags2 = avio_rb32(pb);
500  codec->debug = avio_rb32(pb);
501  /* specific info */
502  switch(codec->codec_type) {
503  case AVMEDIA_TYPE_VIDEO:
504  codec->time_base.num = avio_rb32(pb);
505  codec->time_base.den = avio_rb32(pb);
506  codec->width = avio_rb16(pb);
507  codec->height = avio_rb16(pb);
508  codec->gop_size = avio_rb16(pb);
509  codec->pix_fmt = avio_rb32(pb);
510  codec->qmin = avio_r8(pb);
511  codec->qmax = avio_r8(pb);
512  codec->max_qdiff = avio_r8(pb);
513  codec->qcompress = avio_rb16(pb) / 10000.0;
514  codec->qblur = avio_rb16(pb) / 10000.0;
515  codec->bit_rate_tolerance = avio_rb32(pb);
516  avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));
517  codec->rc_eq = av_strdup(rc_eq_buf);
518  codec->rc_max_rate = avio_rb32(pb);
519  codec->rc_min_rate = avio_rb32(pb);
520  codec->rc_buffer_size = avio_rb32(pb);
521  codec->i_quant_factor = av_int2double(avio_rb64(pb));
522  codec->b_quant_factor = av_int2double(avio_rb64(pb));
523  codec->i_quant_offset = av_int2double(avio_rb64(pb));
524  codec->b_quant_offset = av_int2double(avio_rb64(pb));
525  codec->dct_algo = avio_rb32(pb);
526  codec->strict_std_compliance = avio_rb32(pb);
527  codec->max_b_frames = avio_rb32(pb);
528  codec->mpeg_quant = avio_rb32(pb);
529  codec->intra_dc_precision = avio_rb32(pb);
530  codec->me_method = avio_rb32(pb);
531  codec->mb_decision = avio_rb32(pb);
532  codec->nsse_weight = avio_rb32(pb);
533  codec->frame_skip_cmp = avio_rb32(pb);
534  codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));
535  codec->codec_tag = avio_rb32(pb);
536  codec->thread_count = avio_r8(pb);
537  codec->coder_type = avio_rb32(pb);
538  codec->me_cmp = avio_rb32(pb);
539  codec->me_subpel_quality = avio_rb32(pb);
540  codec->me_range = avio_rb32(pb);
541  codec->keyint_min = avio_rb32(pb);
542  codec->scenechange_threshold = avio_rb32(pb);
543  codec->b_frame_strategy = avio_rb32(pb);
544  codec->qcompress = av_int2double(avio_rb64(pb));
545  codec->qblur = av_int2double(avio_rb64(pb));
546  codec->max_qdiff = avio_rb32(pb);
547  codec->refs = avio_rb32(pb);
548  break;
549  case AVMEDIA_TYPE_AUDIO:
550  codec->sample_rate = avio_rb32(pb);
551  codec->channels = avio_rl16(pb);
552  codec->frame_size = avio_rl16(pb);
553  break;
554  default:
555  goto fail;
556  }
557  if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
558  if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)
559  return AVERROR(ENOMEM);
560  }
561  }
562 
563  /* get until end of block reached */
564  while ((avio_tell(pb) % ffm->packet_size) != 0)
565  avio_r8(pb);
566 
567  /* init packet demux */
568  ffm->packet_ptr = ffm->packet;
569  ffm->packet_end = ffm->packet;
570  ffm->frame_offset = 0;
571  ffm->dts = 0;
572  ffm->read_state = READ_HEADER;
573  ffm->first_packet = 1;
574  return 0;
575  fail:
576  ffm_close(s);
577  return -1;
578 }
579 
580 /* return < 0 if eof */
581 static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)
582 {
583  int size;
584  FFMContext *ffm = s->priv_data;
585  int duration, ret;
586 
587  switch(ffm->read_state) {
588  case READ_HEADER:
589  if ((ret = ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) < 0)
590  return ret;
591 
592  av_dlog(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
593  avio_tell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);
594  if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
595  FRAME_HEADER_SIZE)
596  return -1;
597  if (ffm->header[1] & FLAG_DTS)
598  if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)
599  return -1;
600  ffm->read_state = READ_DATA;
601  /* fall through */
602  case READ_DATA:
603  size = AV_RB24(ffm->header + 2);
604  if ((ret = ffm_is_avail_data(s, size)) < 0)
605  return ret;
606 
607  duration = AV_RB24(ffm->header + 5);
608 
609  if (av_new_packet(pkt, size) < 0) {
610  return AVERROR(ENOMEM);
611  }
612  pkt->stream_index = ffm->header[0];
613  if ((unsigned)pkt->stream_index >= s->nb_streams) {
614  av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);
615  av_free_packet(pkt);
616  ffm->read_state = READ_HEADER;
617  return -1;
618  }
619  pkt->pos = avio_tell(s->pb);
620  if (ffm->header[1] & FLAG_KEY_FRAME)
621  pkt->flags |= AV_PKT_FLAG_KEY;
622 
623  ffm->read_state = READ_HEADER;
624  if (ffm_read_data(s, pkt->data, size, 0) != size) {
625  /* bad case: desynchronized packet. we cancel all the packet loading */
626  av_free_packet(pkt);
627  return -1;
628  }
629  pkt->pts = AV_RB64(ffm->header+8);
630  if (ffm->header[1] & FLAG_DTS)
631  pkt->dts = pkt->pts - AV_RB32(ffm->header+16);
632  else
633  pkt->dts = pkt->pts;
634  pkt->duration = duration;
635  break;
636  }
637  return 0;
638 }
639 
640 /* seek to a given time in the file. The file read pointer is
641  positioned at or before pts. XXX: the following code is quite
642  approximative */
643 static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)
644 {
645  FFMContext *ffm = s->priv_data;
646  int64_t pos_min, pos_max, pos;
647  int64_t pts_min, pts_max, pts;
648  double pos1;
649 
650  av_dlog(s, "wanted_pts=%0.6f\n", wanted_pts / 1000000.0);
651  /* find the position using linear interpolation (better than
652  dichotomy in typical cases) */
653  if (ffm->write_index && ffm->write_index < ffm->file_size) {
654  if (get_dts(s, FFM_PACKET_SIZE) < wanted_pts) {
655  pos_min = FFM_PACKET_SIZE;
656  pos_max = ffm->write_index - FFM_PACKET_SIZE;
657  } else {
658  pos_min = ffm->write_index;
659  pos_max = ffm->file_size - FFM_PACKET_SIZE;
660  }
661  } else {
662  pos_min = FFM_PACKET_SIZE;
663  pos_max = ffm->file_size - FFM_PACKET_SIZE;
664  }
665  while (pos_min <= pos_max) {
666  pts_min = get_dts(s, pos_min);
667  pts_max = get_dts(s, pos_max);
668  if (pts_min > wanted_pts || pts_max <= wanted_pts) {
669  pos = pts_min > wanted_pts ? pos_min : pos_max;
670  goto found;
671  }
672  /* linear interpolation */
673  pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /
674  (double)(pts_max - pts_min);
675  pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;
676  if (pos <= pos_min)
677  pos = pos_min;
678  else if (pos >= pos_max)
679  pos = pos_max;
680  pts = get_dts(s, pos);
681  /* check if we are lucky */
682  if (pts == wanted_pts) {
683  goto found;
684  } else if (pts > wanted_pts) {
685  pos_max = pos - FFM_PACKET_SIZE;
686  } else {
687  pos_min = pos + FFM_PACKET_SIZE;
688  }
689  }
690  pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;
691 
692  found:
693  if (ffm_seek1(s, pos) < 0)
694  return -1;
695 
696  /* reset read state */
697  ffm->read_state = READ_HEADER;
698  ffm->packet_ptr = ffm->packet;
699  ffm->packet_end = ffm->packet;
700  ffm->first_packet = 1;
701 
702  return 0;
703 }
704 
705 static int ffm_probe(AVProbeData *p)
706 {
707  if (
708  p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&
709  (p->buf[3] == '1' || p->buf[3] == '2'))
710  return AVPROBE_SCORE_MAX + 1;
711  return 0;
712 }
713 
714 AVInputFormat ff_ffm_demuxer = {
715  .name = "ffm",
716  .long_name = NULL_IF_CONFIG_SMALL("FFM (FFserver live feed)"),
717  .priv_data_size = sizeof(FFMContext),
718  .read_probe = ffm_probe,
719  .read_header = ffm_read_header,
720  .read_packet = ffm_read_packet,
721  .read_close = ffm_close,
722  .read_seek = ffm_seek,
723 };
Generated on Sun Mar 8 2015 02:35:09 for FFmpeg by   doxygen 1.8.2