hls.c
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1 /*
2  * Apple HTTP Live Streaming demuxer
3  * Copyright (c) 2010 Martin Storsjo
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "libavutil/avstring.h"
29 #include "libavutil/intreadwrite.h"
30 #include "libavutil/mathematics.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/dict.h"
33 #include "libavutil/time.h"
34 #include "avformat.h"
35 #include "internal.h"
36 #include "avio_internal.h"
37 #include "url.h"
38 
39 #define INITIAL_BUFFER_SIZE 32768
40 
41 /*
42  * An apple http stream consists of a playlist with media segment files,
43  * played sequentially. There may be several playlists with the same
44  * video content, in different bandwidth variants, that are played in
45  * parallel (preferably only one bandwidth variant at a time). In this case,
46  * the user supplied the url to a main playlist that only lists the variant
47  * playlists.
48  *
49  * If the main playlist doesn't point at any variants, we still create
50  * one anonymous toplevel variant for this, to maintain the structure.
51  */
52 
53 enum KeyType {
56 };
57 
58 struct segment {
59  int duration;
63  uint8_t iv[16];
64 };
65 
66 /*
67  * Each variant has its own demuxer. If it currently is active,
68  * it has an open AVIOContext too, and potentially an AVPacket
69  * containing the next packet from this stream.
70  */
71 struct variant {
72  int bandwidth;
78  int index;
82 
83  int finished;
87  struct segment **segments;
90  int64_t last_load_time;
91 
93  uint8_t key[16];
94 };
95 
96 typedef struct HLSContext {
98  struct variant **variants;
103  int64_t seek_timestamp;
106 } HLSContext;
107 
108 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
109 {
110  int len = ff_get_line(s, buf, maxlen);
111  while (len > 0 && isspace(buf[len - 1]))
112  buf[--len] = '\0';
113  return len;
114 }
115 
116 static void free_segment_list(struct variant *var)
117 {
118  int i;
119  for (i = 0; i < var->n_segments; i++)
120  av_free(var->segments[i]);
121  av_freep(&var->segments);
122  var->n_segments = 0;
123 }
124 
126 {
127  int i;
128  for (i = 0; i < c->n_variants; i++) {
129  struct variant *var = c->variants[i];
130  free_segment_list(var);
131  av_free_packet(&var->pkt);
132  av_free(var->pb.buffer);
133  if (var->input)
134  ffurl_close(var->input);
135  if (var->ctx) {
136  var->ctx->pb = NULL;
137  avformat_close_input(&var->ctx);
138  }
139  av_free(var);
140  }
141  av_freep(&c->variants);
142  c->n_variants = 0;
143 }
144 
145 /*
146  * Used to reset a statically allocated AVPacket to a clean slate,
147  * containing no data.
148  */
149 static void reset_packet(AVPacket *pkt)
150 {
151  av_init_packet(pkt);
152  pkt->data = NULL;
153 }
154 
155 static struct variant *new_variant(HLSContext *c, int bandwidth,
156  const char *url, const char *base)
157 {
158  struct variant *var = av_mallocz(sizeof(struct variant));
159  if (!var)
160  return NULL;
161  reset_packet(&var->pkt);
162  var->bandwidth = bandwidth;
163  ff_make_absolute_url(var->url, sizeof(var->url), base, url);
164  dynarray_add(&c->variants, &c->n_variants, var);
165  return var;
166 }
167 
168 struct variant_info {
169  char bandwidth[20];
170 };
171 
172 static void handle_variant_args(struct variant_info *info, const char *key,
173  int key_len, char **dest, int *dest_len)
174 {
175  if (!strncmp(key, "BANDWIDTH=", key_len)) {
176  *dest = info->bandwidth;
177  *dest_len = sizeof(info->bandwidth);
178  }
179 }
180 
181 struct key_info {
183  char method[10];
184  char iv[35];
185 };
186 
187 static void handle_key_args(struct key_info *info, const char *key,
188  int key_len, char **dest, int *dest_len)
189 {
190  if (!strncmp(key, "METHOD=", key_len)) {
191  *dest = info->method;
192  *dest_len = sizeof(info->method);
193  } else if (!strncmp(key, "URI=", key_len)) {
194  *dest = info->uri;
195  *dest_len = sizeof(info->uri);
196  } else if (!strncmp(key, "IV=", key_len)) {
197  *dest = info->iv;
198  *dest_len = sizeof(info->iv);
199  }
200 }
201 
202 static int parse_playlist(HLSContext *c, const char *url,
203  struct variant *var, AVIOContext *in)
204 {
205  int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
206  enum KeyType key_type = KEY_NONE;
207  uint8_t iv[16] = "";
208  int has_iv = 0;
209  char key[MAX_URL_SIZE] = "";
210  char line[1024];
211  const char *ptr;
212  int close_in = 0;
213 
214  if (!in) {
215  close_in = 1;
216  if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
217  c->interrupt_callback, NULL)) < 0)
218  return ret;
219  }
220 
221  read_chomp_line(in, line, sizeof(line));
222  if (strcmp(line, "#EXTM3U")) {
223  ret = AVERROR_INVALIDDATA;
224  goto fail;
225  }
226 
227  if (var) {
228  free_segment_list(var);
229  var->finished = 0;
230  }
231  while (!in->eof_reached) {
232  read_chomp_line(in, line, sizeof(line));
233  if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
234  struct variant_info info = {{0}};
235  is_variant = 1;
237  &info);
238  bandwidth = atoi(info.bandwidth);
239  } else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
240  struct key_info info = {{0}};
242  &info);
243  key_type = KEY_NONE;
244  has_iv = 0;
245  if (!strcmp(info.method, "AES-128"))
246  key_type = KEY_AES_128;
247  if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
248  ff_hex_to_data(iv, info.iv + 2);
249  has_iv = 1;
250  }
251  av_strlcpy(key, info.uri, sizeof(key));
252  } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
253  if (!var) {
254  var = new_variant(c, 0, url, NULL);
255  if (!var) {
256  ret = AVERROR(ENOMEM);
257  goto fail;
258  }
259  }
260  var->target_duration = atoi(ptr);
261  } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
262  if (!var) {
263  var = new_variant(c, 0, url, NULL);
264  if (!var) {
265  ret = AVERROR(ENOMEM);
266  goto fail;
267  }
268  }
269  var->start_seq_no = atoi(ptr);
270  } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
271  if (var)
272  var->finished = 1;
273  } else if (av_strstart(line, "#EXTINF:", &ptr)) {
274  is_segment = 1;
275  duration = atoi(ptr);
276  } else if (av_strstart(line, "#", NULL)) {
277  continue;
278  } else if (line[0]) {
279  if (is_variant) {
280  if (!new_variant(c, bandwidth, line, url)) {
281  ret = AVERROR(ENOMEM);
282  goto fail;
283  }
284  is_variant = 0;
285  bandwidth = 0;
286  }
287  if (is_segment) {
288  struct segment *seg;
289  if (!var) {
290  var = new_variant(c, 0, url, NULL);
291  if (!var) {
292  ret = AVERROR(ENOMEM);
293  goto fail;
294  }
295  }
296  seg = av_malloc(sizeof(struct segment));
297  if (!seg) {
298  ret = AVERROR(ENOMEM);
299  goto fail;
300  }
301  seg->duration = duration;
302  seg->key_type = key_type;
303  if (has_iv) {
304  memcpy(seg->iv, iv, sizeof(iv));
305  } else {
306  int seq = var->start_seq_no + var->n_segments;
307  memset(seg->iv, 0, sizeof(seg->iv));
308  AV_WB32(seg->iv + 12, seq);
309  }
310  ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);
311  ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
312  dynarray_add(&var->segments, &var->n_segments, seg);
313  is_segment = 0;
314  }
315  }
316  }
317  if (var)
318  var->last_load_time = av_gettime();
319 
320 fail:
321  if (close_in)
322  avio_close(in);
323  return ret;
324 }
325 
326 static int open_input(struct variant *var)
327 {
328  struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
329  if (seg->key_type == KEY_NONE) {
330  return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
331  &var->parent->interrupt_callback, NULL);
332  } else if (seg->key_type == KEY_AES_128) {
333  char iv[33], key[33], url[MAX_URL_SIZE];
334  int ret;
335  if (strcmp(seg->key, var->key_url)) {
336  URLContext *uc;
337  if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
338  &var->parent->interrupt_callback, NULL) == 0) {
339  if (ffurl_read_complete(uc, var->key, sizeof(var->key))
340  != sizeof(var->key)) {
341  av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
342  seg->key);
343  }
344  ffurl_close(uc);
345  } else {
346  av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
347  seg->key);
348  }
349  av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
350  }
351  ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
352  ff_data_to_hex(key, var->key, sizeof(var->key), 0);
353  iv[32] = key[32] = '\0';
354  if (strstr(seg->url, "://"))
355  snprintf(url, sizeof(url), "crypto+%s", seg->url);
356  else
357  snprintf(url, sizeof(url), "crypto:%s", seg->url);
358  if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
359  &var->parent->interrupt_callback)) < 0)
360  return ret;
361  av_opt_set(var->input->priv_data, "key", key, 0);
362  av_opt_set(var->input->priv_data, "iv", iv, 0);
363  if ((ret = ffurl_connect(var->input, NULL)) < 0) {
364  ffurl_close(var->input);
365  var->input = NULL;
366  return ret;
367  }
368  return 0;
369  }
370  return AVERROR(ENOSYS);
371 }
372 
373 static int read_data(void *opaque, uint8_t *buf, int buf_size)
374 {
375  struct variant *v = opaque;
376  HLSContext *c = v->parent->priv_data;
377  int ret, i;
378 
379 restart:
380  if (!v->input) {
381  /* If this is a live stream and the reload interval has elapsed since
382  * the last playlist reload, reload the variant playlists now. */
383  int64_t reload_interval = v->n_segments > 0 ?
384  v->segments[v->n_segments - 1]->duration :
385  v->target_duration;
386  reload_interval *= 1000000;
387 
388 reload:
389  if (!v->finished &&
390  av_gettime() - v->last_load_time >= reload_interval) {
391  if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
392  return ret;
393  /* If we need to reload the playlist again below (if
394  * there's still no more segments), switch to a reload
395  * interval of half the target duration. */
396  reload_interval = v->target_duration * 500000;
397  }
398  if (v->cur_seq_no < v->start_seq_no) {
400  "skipping %d segments ahead, expired from playlists\n",
401  v->start_seq_no - v->cur_seq_no);
402  v->cur_seq_no = v->start_seq_no;
403  }
404  if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
405  if (v->finished)
406  return AVERROR_EOF;
407  while (av_gettime() - v->last_load_time < reload_interval) {
409  return AVERROR_EXIT;
410  av_usleep(100*1000);
411  }
412  /* Enough time has elapsed since the last reload */
413  goto reload;
414  }
415 
416  ret = open_input(v);
417  if (ret < 0)
418  return ret;
419  }
420  ret = ffurl_read(v->input, buf, buf_size);
421  if (ret > 0)
422  return ret;
423  ffurl_close(v->input);
424  v->input = NULL;
425  v->cur_seq_no++;
426 
427  c->end_of_segment = 1;
428  c->cur_seq_no = v->cur_seq_no;
429 
430  if (v->ctx && v->ctx->nb_streams) {
431  v->needed = 0;
432  for (i = v->stream_offset; i < v->stream_offset + v->ctx->nb_streams;
433  i++) {
434  if (v->parent->streams[i]->discard < AVDISCARD_ALL)
435  v->needed = 1;
436  }
437  }
438  if (!v->needed) {
439  av_log(v->parent, AV_LOG_INFO, "No longer receiving variant %d\n",
440  v->index);
441  return AVERROR_EOF;
442  }
443  goto restart;
444 }
445 
447 {
448  HLSContext *c = s->priv_data;
449  int ret = 0, i, j, stream_offset = 0;
450 
452 
453  if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
454  goto fail;
455 
456  if (c->n_variants == 0) {
457  av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
458  ret = AVERROR_EOF;
459  goto fail;
460  }
461  /* If the playlist only contained variants, parse each individual
462  * variant playlist. */
463  if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
464  for (i = 0; i < c->n_variants; i++) {
465  struct variant *v = c->variants[i];
466  if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
467  goto fail;
468  }
469  }
470 
471  if (c->variants[0]->n_segments == 0) {
472  av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
473  ret = AVERROR_EOF;
474  goto fail;
475  }
476 
477  /* If this isn't a live stream, calculate the total duration of the
478  * stream. */
479  if (c->variants[0]->finished) {
480  int64_t duration = 0;
481  for (i = 0; i < c->variants[0]->n_segments; i++)
482  duration += c->variants[0]->segments[i]->duration;
483  s->duration = duration * AV_TIME_BASE;
484  }
485 
486  /* Open the demuxer for each variant */
487  for (i = 0; i < c->n_variants; i++) {
488  struct variant *v = c->variants[i];
489  AVInputFormat *in_fmt = NULL;
490  char bitrate_str[20];
491  if (v->n_segments == 0)
492  continue;
493 
494  if (!(v->ctx = avformat_alloc_context())) {
495  ret = AVERROR(ENOMEM);
496  goto fail;
497  }
498 
499  v->index = i;
500  v->needed = 1;
501  v->parent = s;
502 
503  /* If this is a live stream with more than 3 segments, start at the
504  * third last segment. */
505  v->cur_seq_no = v->start_seq_no;
506  if (!v->finished && v->n_segments > 3)
507  v->cur_seq_no = v->start_seq_no + v->n_segments - 3;
508 
511  read_data, NULL, NULL);
512  v->pb.seekable = 0;
513  ret = av_probe_input_buffer(&v->pb, &in_fmt, v->segments[0]->url,
514  NULL, 0, 0);
515  if (ret < 0) {
516  /* Free the ctx - it isn't initialized properly at this point,
517  * so avformat_close_input shouldn't be called. If
518  * avformat_open_input fails below, it frees and zeros the
519  * context, so it doesn't need any special treatment like this. */
521  v->ctx = NULL;
522  goto fail;
523  }
524  v->ctx->pb = &v->pb;
525  ret = avformat_open_input(&v->ctx, v->segments[0]->url, in_fmt, NULL);
526  if (ret < 0)
527  goto fail;
529  snprintf(bitrate_str, sizeof(bitrate_str), "%d", v->bandwidth);
530  /* Create new AVStreams for each stream in this variant */
531  for (j = 0; j < v->ctx->nb_streams; j++) {
533  if (!st) {
534  ret = AVERROR(ENOMEM);
535  goto fail;
536  }
537  st->id = i;
539  if (v->bandwidth)
540  av_dict_set(&st->metadata, "variant_bitrate", bitrate_str,
541  0);
542  }
543  stream_offset += v->ctx->nb_streams;
544  }
545 
546  c->first_packet = 1;
549 
550  return 0;
551 fail:
553  return ret;
554 }
555 
556 static int recheck_discard_flags(AVFormatContext *s, int first)
557 {
558  HLSContext *c = s->priv_data;
559  int i, changed = 0;
560 
561  /* Check if any new streams are needed */
562  for (i = 0; i < c->n_variants; i++)
563  c->variants[i]->cur_needed = 0;;
564 
565  for (i = 0; i < s->nb_streams; i++) {
566  AVStream *st = s->streams[i];
567  struct variant *var = c->variants[s->streams[i]->id];
568  if (st->discard < AVDISCARD_ALL)
569  var->cur_needed = 1;
570  }
571  for (i = 0; i < c->n_variants; i++) {
572  struct variant *v = c->variants[i];
573  if (v->cur_needed && !v->needed) {
574  v->needed = 1;
575  changed = 1;
576  v->cur_seq_no = c->cur_seq_no;
577  v->pb.eof_reached = 0;
578  av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
579  } else if (first && !v->cur_needed && v->needed) {
580  if (v->input)
581  ffurl_close(v->input);
582  v->input = NULL;
583  v->needed = 0;
584  changed = 1;
585  av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);
586  }
587  }
588  return changed;
589 }
590 
592 {
593  HLSContext *c = s->priv_data;
594  int ret, i, minvariant = -1;
595 
596  if (c->first_packet) {
597  recheck_discard_flags(s, 1);
598  c->first_packet = 0;
599  }
600 
601 start:
602  c->end_of_segment = 0;
603  for (i = 0; i < c->n_variants; i++) {
604  struct variant *var = c->variants[i];
605  /* Make sure we've got one buffered packet from each open variant
606  * stream */
607  if (var->needed && !var->pkt.data) {
608  while (1) {
609  int64_t ts_diff;
610  AVStream *st;
611  ret = av_read_frame(var->ctx, &var->pkt);
612  if (ret < 0) {
613  if (!var->pb.eof_reached)
614  return ret;
615  reset_packet(&var->pkt);
616  break;
617  } else {
619  c->first_timestamp = var->pkt.dts;
620  }
621 
622  if (c->seek_timestamp == AV_NOPTS_VALUE)
623  break;
624 
625  if (var->pkt.dts == AV_NOPTS_VALUE) {
627  break;
628  }
629 
630  st = var->ctx->streams[var->pkt.stream_index];
631  ts_diff = av_rescale_rnd(var->pkt.dts, AV_TIME_BASE,
632  st->time_base.den, AV_ROUND_DOWN) -
633  c->seek_timestamp;
634  if (ts_diff >= 0 && (c->seek_flags & AVSEEK_FLAG_ANY ||
635  var->pkt.flags & AV_PKT_FLAG_KEY)) {
637  break;
638  }
639  }
640  }
641  /* Check if this stream has the packet with the lowest dts */
642  if (var->pkt.data) {
643  if (minvariant < 0 ||
644  var->pkt.dts < c->variants[minvariant]->pkt.dts)
645  minvariant = i;
646  }
647  }
648  if (c->end_of_segment) {
649  if (recheck_discard_flags(s, 0))
650  goto start;
651  }
652  /* If we got a packet, return it */
653  if (minvariant >= 0) {
654  *pkt = c->variants[minvariant]->pkt;
655  pkt->stream_index += c->variants[minvariant]->stream_offset;
656  reset_packet(&c->variants[minvariant]->pkt);
657  return 0;
658  }
659  return AVERROR_EOF;
660 }
661 
663 {
664  HLSContext *c = s->priv_data;
665 
667  return 0;
668 }
669 
670 static int hls_read_seek(AVFormatContext *s, int stream_index,
671  int64_t timestamp, int flags)
672 {
673  HLSContext *c = s->priv_data;
674  int i, j, ret;
675 
676  if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)
677  return AVERROR(ENOSYS);
678 
679  c->seek_flags = flags;
680  c->seek_timestamp = stream_index < 0 ? timestamp :
681  av_rescale_rnd(timestamp, AV_TIME_BASE,
682  s->streams[stream_index]->time_base.den,
683  flags & AVSEEK_FLAG_BACKWARD ?
685  timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
686  s->streams[stream_index]->time_base.den :
688  AV_ROUND_DOWN : AV_ROUND_UP);
689  if (s->duration < c->seek_timestamp) {
691  return AVERROR(EIO);
692  }
693 
694  ret = AVERROR(EIO);
695  for (i = 0; i < c->n_variants; i++) {
696  /* Reset reading */
697  struct variant *var = c->variants[i];
698  int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? 0 :
700  stream_index >= 0 ? s->streams[stream_index]->time_base.den : AV_TIME_BASE,
701  flags & AVSEEK_FLAG_BACKWARD ? AV_ROUND_DOWN : AV_ROUND_UP);
702  if (var->input) {
703  ffurl_close(var->input);
704  var->input = NULL;
705  }
706  av_free_packet(&var->pkt);
707  reset_packet(&var->pkt);
708  var->pb.eof_reached = 0;
709  /* Clear any buffered data */
710  var->pb.buf_end = var->pb.buf_ptr = var->pb.buffer;
711  /* Reset the pos, to let the mpegts demuxer know we've seeked. */
712  var->pb.pos = 0;
713 
714  /* Locate the segment that contains the target timestamp */
715  for (j = 0; j < var->n_segments; j++) {
716  if (timestamp >= pos &&
717  timestamp < pos + var->segments[j]->duration) {
718  var->cur_seq_no = var->start_seq_no + j;
719  ret = 0;
720  break;
721  }
722  pos += var->segments[j]->duration;
723  }
724  if (ret)
726  }
727  return ret;
728 }
729 
730 static int hls_probe(AVProbeData *p)
731 {
732  /* Require #EXTM3U at the start, and either one of the ones below
733  * somewhere for a proper match. */
734  if (strncmp(p->buf, "#EXTM3U", 7))
735  return 0;
736  if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
737  strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
738  strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
739  return AVPROBE_SCORE_MAX;
740  return 0;
741 }
742 
744  .name = "hls,applehttp",
745  .long_name = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming"),
746  .priv_data_size = sizeof(HLSContext),
752 };