applehttpproto.c
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1 /*
2  * Apple HTTP Live Streaming Protocol Handler
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 "avformat.h"
30 #include "internal.h"
31 #include "url.h"
32 #include <unistd.h>
33 
34 /*
35  * An apple http stream consists of a playlist with media segment files,
36  * played sequentially. There may be several playlists with the same
37  * video content, in different bandwidth variants, that are played in
38  * parallel (preferrably only one bandwidth variant at a time). In this case,
39  * the user supplied the url to a main playlist that only lists the variant
40  * playlists.
41  *
42  * If the main playlist doesn't point at any variants, we still create
43  * one anonymous toplevel variant for this, to maintain the structure.
44  */
45 
46 struct segment {
47  int duration;
48  char url[MAX_URL_SIZE];
49 };
50 
51 struct variant {
52  int bandwidth;
53  char url[MAX_URL_SIZE];
54 };
55 
56 typedef struct AppleHTTPContext {
60  int finished;
62  struct segment **segments;
63  int n_variants;
64  struct variant **variants;
65  int cur_seq_no;
67  int64_t last_load_time;
69 
70 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
71 {
72  int len = ff_get_line(s, buf, maxlen);
73  while (len > 0 && isspace(buf[len - 1]))
74  buf[--len] = '\0';
75  return len;
76 }
77 
79 {
80  int i;
81  for (i = 0; i < s->n_segments; i++)
82  av_free(s->segments[i]);
83  av_freep(&s->segments);
84  s->n_segments = 0;
85 }
86 
88 {
89  int i;
90  for (i = 0; i < s->n_variants; i++)
91  av_free(s->variants[i]);
92  av_freep(&s->variants);
93  s->n_variants = 0;
94 }
95 
96 struct variant_info {
97  char bandwidth[20];
98 };
99 
100 static void handle_variant_args(struct variant_info *info, const char *key,
101  int key_len, char **dest, int *dest_len)
102 {
103  if (!strncmp(key, "BANDWIDTH=", key_len)) {
104  *dest = info->bandwidth;
105  *dest_len = sizeof(info->bandwidth);
106  }
107 }
108 
109 static int parse_playlist(URLContext *h, const char *url)
110 {
111  AppleHTTPContext *s = h->priv_data;
112  AVIOContext *in;
113  int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
114  char line[1024];
115  const char *ptr;
116 
117  if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
118  &h->interrupt_callback, NULL)) < 0)
119  return ret;
120 
121  read_chomp_line(in, line, sizeof(line));
122  if (strcmp(line, "#EXTM3U"))
123  return AVERROR_INVALIDDATA;
124 
126  s->finished = 0;
127  while (!in->eof_reached) {
128  read_chomp_line(in, line, sizeof(line));
129  if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
130  struct variant_info info = {{0}};
131  is_variant = 1;
133  &info);
134  bandwidth = atoi(info.bandwidth);
135  } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
136  s->target_duration = atoi(ptr);
137  } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
138  s->start_seq_no = atoi(ptr);
139  } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
140  s->finished = 1;
141  } else if (av_strstart(line, "#EXTINF:", &ptr)) {
142  is_segment = 1;
143  duration = atoi(ptr);
144  } else if (av_strstart(line, "#", NULL)) {
145  continue;
146  } else if (line[0]) {
147  if (is_segment) {
148  struct segment *seg = av_malloc(sizeof(struct segment));
149  if (!seg) {
150  ret = AVERROR(ENOMEM);
151  goto fail;
152  }
153  seg->duration = duration;
154  ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
155  dynarray_add(&s->segments, &s->n_segments, seg);
156  is_segment = 0;
157  } else if (is_variant) {
158  struct variant *var = av_malloc(sizeof(struct variant));
159  if (!var) {
160  ret = AVERROR(ENOMEM);
161  goto fail;
162  }
163  var->bandwidth = bandwidth;
164  ff_make_absolute_url(var->url, sizeof(var->url), url, line);
165  dynarray_add(&s->variants, &s->n_variants, var);
166  is_variant = 0;
167  }
168  }
169  }
170  s->last_load_time = av_gettime();
171 
172 fail:
173  avio_close(in);
174  return ret;
175 }
176 
178 {
179  AppleHTTPContext *s = h->priv_data;
180 
183  ffurl_close(s->seg_hd);
184  return 0;
185 }
186 
187 static int applehttp_open(URLContext *h, const char *uri, int flags)
188 {
189  AppleHTTPContext *s = h->priv_data;
190  int ret, i;
191  const char *nested_url;
192 
193  if (flags & AVIO_FLAG_WRITE)
194  return AVERROR(ENOSYS);
195 
196  h->is_streamed = 1;
197 
198  if (av_strstart(uri, "applehttp+", &nested_url)) {
199  av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
200  } else if (av_strstart(uri, "applehttp://", &nested_url)) {
201  av_strlcpy(s->playlisturl, "http://", sizeof(s->playlisturl));
202  av_strlcat(s->playlisturl, nested_url, sizeof(s->playlisturl));
203  } else {
204  av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
205  ret = AVERROR(EINVAL);
206  goto fail;
207  }
208 
209  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
210  goto fail;
211 
212  if (s->n_segments == 0 && s->n_variants > 0) {
213  int max_bandwidth = 0, maxvar = -1;
214  for (i = 0; i < s->n_variants; i++) {
215  if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
216  max_bandwidth = s->variants[i]->bandwidth;
217  maxvar = i;
218  }
219  }
220  av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
221  sizeof(s->playlisturl));
222  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
223  goto fail;
224  }
225 
226  if (s->n_segments == 0) {
227  av_log(h, AV_LOG_WARNING, "Empty playlist\n");
228  ret = AVERROR(EIO);
229  goto fail;
230  }
231  s->cur_seq_no = s->start_seq_no;
232  if (!s->finished && s->n_segments >= 3)
233  s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
234 
235  return 0;
236 
237 fail:
238  applehttp_close(h);
239  return ret;
240 }
241 
242 static int applehttp_read(URLContext *h, uint8_t *buf, int size)
243 {
244  AppleHTTPContext *s = h->priv_data;
245  const char *url;
246  int ret;
247  int64_t reload_interval;
248 
249 start:
250  if (s->seg_hd) {
251  ret = ffurl_read(s->seg_hd, buf, size);
252  if (ret > 0)
253  return ret;
254  }
255  if (s->seg_hd) {
256  ffurl_close(s->seg_hd);
257  s->seg_hd = NULL;
258  s->cur_seq_no++;
259  }
260  reload_interval = s->n_segments > 0 ?
261  s->segments[s->n_segments - 1]->duration :
262  s->target_duration;
263  reload_interval *= 1000000;
264 retry:
265  if (!s->finished) {
266  int64_t now = av_gettime();
267  if (now - s->last_load_time >= reload_interval) {
268  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
269  return ret;
270  /* If we need to reload the playlist again below (if
271  * there's still no more segments), switch to a reload
272  * interval of half the target duration. */
273  reload_interval = s->target_duration * 500000;
274  }
275  }
276  if (s->cur_seq_no < s->start_seq_no) {
278  "skipping %d segments ahead, expired from playlist\n",
279  s->start_seq_no - s->cur_seq_no);
280  s->cur_seq_no = s->start_seq_no;
281  }
282  if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
283  if (s->finished)
284  return AVERROR_EOF;
285  while (av_gettime() - s->last_load_time < reload_interval) {
287  return AVERROR_EXIT;
288  usleep(100*1000);
289  }
290  goto retry;
291  }
292  url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
293  av_log(h, AV_LOG_DEBUG, "opening %s\n", url);
294  ret = ffurl_open(&s->seg_hd, url, AVIO_FLAG_READ,
295  &h->interrupt_callback, NULL);
296  if (ret < 0) {
298  return AVERROR_EXIT;
299  av_log(h, AV_LOG_WARNING, "Unable to open %s\n", url);
300  s->cur_seq_no++;
301  goto retry;
302  }
303  goto start;
304 }
305 
307  .name = "applehttp",
308  .url_open = applehttp_open,
309  .url_read = applehttp_read,
310  .url_close = applehttp_close,
312  .priv_data_size = sizeof(AppleHTTPContext),
313 };