applehttp.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 "avformat.h"
34 #include "internal.h"
35 #include <unistd.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 (preferrably 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;
75  uint8_t* read_buffer;
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 AppleHTTPContext {
98  struct variant **variants;
105 
106 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
107 {
108  int len = ff_get_line(s, buf, maxlen);
109  while (len > 0 && isspace(buf[len - 1]))
110  buf[--len] = '\0';
111  return len;
112 }
113 
114 static void free_segment_list(struct variant *var)
115 {
116  int i;
117  for (i = 0; i < var->n_segments; i++)
118  av_free(var->segments[i]);
119  av_freep(&var->segments);
120  var->n_segments = 0;
121 }
122 
124 {
125  int i;
126  for (i = 0; i < c->n_variants; i++) {
127  struct variant *var = c->variants[i];
128  free_segment_list(var);
129  av_free_packet(&var->pkt);
130  av_free(var->pb.buffer);
131  if (var->input)
132  ffurl_close(var->input);
133  if (var->ctx) {
134  var->ctx->pb = NULL;
135  avformat_close_input(&var->ctx);
136  }
137  av_free(var);
138  }
139  av_freep(&c->variants);
140  c->n_variants = 0;
141 }
142 
143 /*
144  * Used to reset a statically allocated AVPacket to a clean slate,
145  * containing no data.
146  */
147 static void reset_packet(AVPacket *pkt)
148 {
149  av_init_packet(pkt);
150  pkt->data = NULL;
151 }
152 
154  const char *url, const char *base)
155 {
156  struct variant *var = av_mallocz(sizeof(struct variant));
157  if (!var)
158  return NULL;
159  reset_packet(&var->pkt);
160  var->bandwidth = bandwidth;
161  ff_make_absolute_url(var->url, sizeof(var->url), base, url);
162  dynarray_add(&c->variants, &c->n_variants, var);
163  return var;
164 }
165 
166 struct variant_info {
167  char bandwidth[20];
168 };
169 
170 static void handle_variant_args(struct variant_info *info, const char *key,
171  int key_len, char **dest, int *dest_len)
172 {
173  if (!strncmp(key, "BANDWIDTH=", key_len)) {
174  *dest = info->bandwidth;
175  *dest_len = sizeof(info->bandwidth);
176  }
177 }
178 
179 struct key_info {
181  char method[10];
182  char iv[35];
183 };
184 
185 static void handle_key_args(struct key_info *info, const char *key,
186  int key_len, char **dest, int *dest_len)
187 {
188  if (!strncmp(key, "METHOD=", key_len)) {
189  *dest = info->method;
190  *dest_len = sizeof(info->method);
191  } else if (!strncmp(key, "URI=", key_len)) {
192  *dest = info->uri;
193  *dest_len = sizeof(info->uri);
194  } else if (!strncmp(key, "IV=", key_len)) {
195  *dest = info->iv;
196  *dest_len = sizeof(info->iv);
197  }
198 }
199 
200 static int parse_playlist(AppleHTTPContext *c, const char *url,
201  struct variant *var, AVIOContext *in)
202 {
203  int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
204  enum KeyType key_type = KEY_NONE;
205  uint8_t iv[16] = "";
206  int has_iv = 0;
207  char key[MAX_URL_SIZE] = "";
208  char line[1024];
209  const char *ptr;
210  int close_in = 0;
211 
212  if (!in) {
213  close_in = 1;
214  if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
215  c->interrupt_callback, NULL)) < 0)
216  return ret;
217  }
218 
219  read_chomp_line(in, line, sizeof(line));
220  if (strcmp(line, "#EXTM3U")) {
221  ret = AVERROR_INVALIDDATA;
222  goto fail;
223  }
224 
225  if (var) {
226  free_segment_list(var);
227  var->finished = 0;
228  }
229  while (!in->eof_reached) {
230  read_chomp_line(in, line, sizeof(line));
231  if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
232  struct variant_info info = {{0}};
233  is_variant = 1;
235  &info);
236  bandwidth = atoi(info.bandwidth);
237  } else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
238  struct key_info info = {{0}};
240  &info);
241  key_type = KEY_NONE;
242  has_iv = 0;
243  if (!strcmp(info.method, "AES-128"))
244  key_type = KEY_AES_128;
245  if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
246  ff_hex_to_data(iv, info.iv + 2);
247  has_iv = 1;
248  }
249  av_strlcpy(key, info.uri, sizeof(key));
250  } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
251  if (!var) {
252  var = new_variant(c, 0, url, NULL);
253  if (!var) {
254  ret = AVERROR(ENOMEM);
255  goto fail;
256  }
257  }
258  var->target_duration = atoi(ptr);
259  } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
260  if (!var) {
261  var = new_variant(c, 0, url, NULL);
262  if (!var) {
263  ret = AVERROR(ENOMEM);
264  goto fail;
265  }
266  }
267  var->start_seq_no = atoi(ptr);
268  } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
269  if (var)
270  var->finished = 1;
271  } else if (av_strstart(line, "#EXTINF:", &ptr)) {
272  is_segment = 1;
273  duration = atoi(ptr);
274  } else if (av_strstart(line, "#", NULL)) {
275  continue;
276  } else if (line[0]) {
277  if (is_variant) {
278  if (!new_variant(c, bandwidth, line, url)) {
279  ret = AVERROR(ENOMEM);
280  goto fail;
281  }
282  is_variant = 0;
283  bandwidth = 0;
284  }
285  if (is_segment) {
286  struct segment *seg;
287  if (!var) {
288  var = new_variant(c, 0, url, NULL);
289  if (!var) {
290  ret = AVERROR(ENOMEM);
291  goto fail;
292  }
293  }
294  seg = av_malloc(sizeof(struct segment));
295  if (!seg) {
296  ret = AVERROR(ENOMEM);
297  goto fail;
298  }
299  seg->duration = duration;
300  seg->key_type = key_type;
301  if (has_iv) {
302  memcpy(seg->iv, iv, sizeof(iv));
303  } else {
304  int seq = var->start_seq_no + var->n_segments;
305  memset(seg->iv, 0, sizeof(seg->iv));
306  AV_WB32(seg->iv + 12, seq);
307  }
308  ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);
309  ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
310  dynarray_add(&var->segments, &var->n_segments, seg);
311  is_segment = 0;
312  }
313  }
314  }
315  if (var)
316  var->last_load_time = av_gettime();
317 
318 fail:
319  if (close_in)
320  avio_close(in);
321  return ret;
322 }
323 
324 static int open_input(struct variant *var)
325 {
326  struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
327  if (seg->key_type == KEY_NONE) {
328  return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
329  &var->parent->interrupt_callback, NULL);
330  } else if (seg->key_type == KEY_AES_128) {
331  char iv[33], key[33], url[MAX_URL_SIZE];
332  int ret;
333  if (strcmp(seg->key, var->key_url)) {
334  URLContext *uc;
335  if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
336  &var->parent->interrupt_callback, NULL) == 0) {
337  if (ffurl_read_complete(uc, var->key, sizeof(var->key))
338  != sizeof(var->key)) {
339  av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
340  seg->key);
341  }
342  ffurl_close(uc);
343  } else {
344  av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
345  seg->key);
346  }
347  av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
348  }
349  ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
350  ff_data_to_hex(key, var->key, sizeof(var->key), 0);
351  iv[32] = key[32] = '\0';
352  if (strstr(seg->url, "://"))
353  snprintf(url, sizeof(url), "crypto+%s", seg->url);
354  else
355  snprintf(url, sizeof(url), "crypto:%s", seg->url);
356  if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
357  &var->parent->interrupt_callback)) < 0)
358  return ret;
359  av_opt_set(var->input->priv_data, "key", key, 0);
360  av_opt_set(var->input->priv_data, "iv", iv, 0);
361  if ((ret = ffurl_connect(var->input, NULL)) < 0) {
362  ffurl_close(var->input);
363  var->input = NULL;
364  return ret;
365  }
366  return 0;
367  }
368  return AVERROR(ENOSYS);
369 }
370 
371 static int read_data(void *opaque, uint8_t *buf, int buf_size)
372 {
373  struct variant *v = opaque;
375  int ret, i;
376 
377 restart:
378  if (!v->input) {
379  /* If this is a live stream and the reload interval has elapsed since
380  * the last playlist reload, reload the variant playlists now. */
381  int64_t reload_interval = v->n_segments > 0 ?
382  v->segments[v->n_segments - 1]->duration :
383  v->target_duration;
384  reload_interval *= 1000000;
385 
386 reload:
387  if (!v->finished &&
388  av_gettime() - v->last_load_time >= reload_interval) {
389  if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
390  return ret;
391  /* If we need to reload the playlist again below (if
392  * there's still no more segments), switch to a reload
393  * interval of half the target duration. */
394  reload_interval = v->target_duration * 500000;
395  }
396  if (v->cur_seq_no < v->start_seq_no) {
398  "skipping %d segments ahead, expired from playlists\n",
399  v->start_seq_no - v->cur_seq_no);
400  v->cur_seq_no = v->start_seq_no;
401  }
402  if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
403  if (v->finished)
404  return AVERROR_EOF;
405  while (av_gettime() - v->last_load_time < reload_interval) {
407  return AVERROR_EXIT;
408  usleep(100*1000);
409  }
410  /* Enough time has elapsed since the last reload */
411  goto reload;
412  }
413 
414  ret = open_input(v);
415  if (ret < 0)
416  return ret;
417  }
418  ret = ffurl_read(v->input, buf, buf_size);
419  if (ret > 0)
420  return ret;
421  if (ret < 0 && ret != AVERROR_EOF)
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  AppleHTTPContext *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;
548 
549  return 0;
550 fail:
552  return ret;
553 }
554 
555 static int recheck_discard_flags(AVFormatContext *s, int first)
556 {
557  AppleHTTPContext *c = s->priv_data;
558  int i, changed = 0;
559 
560  /* Check if any new streams are needed */
561  for (i = 0; i < c->n_variants; i++)
562  c->variants[i]->cur_needed = 0;;
563 
564  for (i = 0; i < s->nb_streams; i++) {
565  AVStream *st = s->streams[i];
566  struct variant *var = c->variants[s->streams[i]->id];
567  if (st->discard < AVDISCARD_ALL)
568  var->cur_needed = 1;
569  }
570  for (i = 0; i < c->n_variants; i++) {
571  struct variant *v = c->variants[i];
572  if (v->cur_needed && !v->needed) {
573  v->needed = 1;
574  changed = 1;
575  v->cur_seq_no = c->cur_seq_no;
576  v->pb.eof_reached = 0;
577  av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
578  } else if (first && !v->cur_needed && v->needed) {
579  if (v->input)
580  ffurl_close(v->input);
581  v->input = NULL;
582  v->needed = 0;
583  changed = 1;
584  av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);
585  }
586  }
587  return changed;
588 }
589 
591 {
592  AppleHTTPContext *c = s->priv_data;
593  int ret, i, minvariant = -1;
594 
595  if (c->first_packet) {
596  recheck_discard_flags(s, 1);
597  c->first_packet = 0;
598  }
599 
600 start:
601  c->end_of_segment = 0;
602  for (i = 0; i < c->n_variants; i++) {
603  struct variant *var = c->variants[i];
604  /* Make sure we've got one buffered packet from each open variant
605  * stream */
606  if (var->needed && !var->pkt.data) {
607  ret = av_read_frame(var->ctx, &var->pkt);
608  if (ret < 0) {
609  if (!var->pb.eof_reached)
610  return ret;
611  reset_packet(&var->pkt);
612  } else {
614  c->first_timestamp = var->pkt.dts;
615  }
616  }
617  /* Check if this stream has the packet with the lowest dts */
618  if (var->pkt.data) {
619  if (minvariant < 0 ||
620  var->pkt.dts < c->variants[minvariant]->pkt.dts)
621  minvariant = i;
622  }
623  }
624  if (c->end_of_segment) {
625  if (recheck_discard_flags(s, 0))
626  goto start;
627  }
628  /* If we got a packet, return it */
629  if (minvariant >= 0) {
630  *pkt = c->variants[minvariant]->pkt;
631  pkt->stream_index += c->variants[minvariant]->stream_offset;
632  reset_packet(&c->variants[minvariant]->pkt);
633  return 0;
634  }
635  return AVERROR_EOF;
636 }
637 
639 {
640  AppleHTTPContext *c = s->priv_data;
641 
643  return 0;
644 }
645 
646 static int applehttp_read_seek(AVFormatContext *s, int stream_index,
647  int64_t timestamp, int flags)
648 {
649  AppleHTTPContext *c = s->priv_data;
650  int i, j, ret;
651 
652  if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)
653  return AVERROR(ENOSYS);
654 
655  timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
656  s->streams[stream_index]->time_base.den :
659  ret = AVERROR(EIO);
660  for (i = 0; i < c->n_variants; i++) {
661  /* Reset reading */
662  struct variant *var = c->variants[i];
663  int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? 0 :
665  stream_index >= 0 ? s->streams[stream_index]->time_base.den : AV_TIME_BASE,
666  flags & AVSEEK_FLAG_BACKWARD ? AV_ROUND_DOWN : AV_ROUND_UP);
667  if (var->input) {
668  ffurl_close(var->input);
669  var->input = NULL;
670  }
671  av_free_packet(&var->pkt);
672  reset_packet(&var->pkt);
673  var->pb.eof_reached = 0;
674 
675  /* Locate the segment that contains the target timestamp */
676  for (j = 0; j < var->n_segments; j++) {
677  if (timestamp >= pos &&
678  timestamp < pos + var->segments[j]->duration) {
679  var->cur_seq_no = var->start_seq_no + j;
680  ret = 0;
681  break;
682  }
683  pos += var->segments[j]->duration;
684  }
685  }
686  return ret;
687 }
688 
690 {
691  /* Require #EXTM3U at the start, and either one of the ones below
692  * somewhere for a proper match. */
693  if (strncmp(p->buf, "#EXTM3U", 7))
694  return 0;
695  if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
696  strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
697  strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
698  return AVPROBE_SCORE_MAX;
699  return 0;
700 }
701 
703  .name = "applehttp",
704  .long_name = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
705  .priv_data_size = sizeof(AppleHTTPContext),
711 };