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hlsproto.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 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 /**
23  * @file
24  * Apple HTTP Live Streaming Protocol Handler
25  * http://tools.ietf.org/html/draft-pantos-http-live-streaming
26  */
27 
28 #include "libavutil/avstring.h"
29 #include "libavutil/time.h"
30 #include "avformat.h"
31 #include "internal.h"
32 #include "url.h"
33 #include "version.h"
34 
35 /*
36  * An apple http stream consists of a playlist with media segment files,
37  * played sequentially. There may be several playlists with the same
38  * video content, in different bandwidth variants, that are played in
39  * parallel (preferably only one bandwidth variant at a time). In this case,
40  * the user supplied the url to a main playlist that only lists the variant
41  * playlists.
42  *
43  * If the main playlist doesn't point at any variants, we still create
44  * one anonymous toplevel variant for this, to maintain the structure.
45  */
46 
47 struct segment {
48  int64_t duration;
50 };
51 
52 struct variant {
53  int bandwidth;
55 };
56 
57 typedef struct HLSContext {
59  int64_t target_duration;
61  int finished;
63  struct segment **segments;
64  int n_variants;
65  struct variant **variants;
66  int cur_seq_no;
68  int64_t last_load_time;
69 } HLSContext;
70 
71 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
72 {
73  int len = ff_get_line(s, buf, maxlen);
74  while (len > 0 && av_isspace(buf[len - 1]))
75  buf[--len] = '\0';
76  return len;
77 }
78 
80 {
81  int i;
82  for (i = 0; i < s->n_segments; i++)
83  av_free(s->segments[i]);
84  av_freep(&s->segments);
85  s->n_segments = 0;
86 }
87 
89 {
90  int i;
91  for (i = 0; i < s->n_variants; i++)
92  av_free(s->variants[i]);
93  av_freep(&s->variants);
94  s->n_variants = 0;
95 }
96 
97 struct variant_info {
98  char bandwidth[20];
99 };
100 
101 static void handle_variant_args(struct variant_info *info, const char *key,
102  int key_len, char **dest, int *dest_len)
103 {
104  if (!strncmp(key, "BANDWIDTH=", key_len)) {
105  *dest = info->bandwidth;
106  *dest_len = sizeof(info->bandwidth);
107  }
108 }
109 
110 static int parse_playlist(URLContext *h, const char *url)
111 {
112  HLSContext *s = h->priv_data;
113  AVIOContext *in;
114  int ret = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
115  int64_t duration = 0;
116  char line[1024];
117  const char *ptr;
118 
119  if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
120  &h->interrupt_callback, NULL)) < 0)
121  return ret;
122 
123  read_chomp_line(in, line, sizeof(line));
124  if (strcmp(line, "#EXTM3U"))
125  return AVERROR_INVALIDDATA;
126 
128  s->finished = 0;
129  while (!avio_feof(in)) {
130  read_chomp_line(in, line, sizeof(line));
131  if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
132  struct variant_info info = {{0}};
133  is_variant = 1;
135  &info);
136  bandwidth = atoi(info.bandwidth);
137  } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
138  s->target_duration = atoi(ptr) * AV_TIME_BASE;
139  } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
140  s->start_seq_no = atoi(ptr);
141  } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
142  s->finished = 1;
143  } else if (av_strstart(line, "#EXTINF:", &ptr)) {
144  is_segment = 1;
145  duration = atof(ptr) * AV_TIME_BASE;
146  } else if (av_strstart(line, "#", NULL)) {
147  continue;
148  } else if (line[0]) {
149  if (is_segment) {
150  struct segment *seg = av_malloc(sizeof(struct segment));
151  if (!seg) {
152  ret = AVERROR(ENOMEM);
153  goto fail;
154  }
155  seg->duration = duration;
156  ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
157  dynarray_add(&s->segments, &s->n_segments, seg);
158  is_segment = 0;
159  } else if (is_variant) {
160  struct variant *var = av_malloc(sizeof(struct variant));
161  if (!var) {
162  ret = AVERROR(ENOMEM);
163  goto fail;
164  }
165  var->bandwidth = bandwidth;
166  ff_make_absolute_url(var->url, sizeof(var->url), url, line);
167  dynarray_add(&s->variants, &s->n_variants, var);
168  is_variant = 0;
169  }
170  }
171  }
173 
174 fail:
175  avio_close(in);
176  return ret;
177 }
178 
179 static int hls_close(URLContext *h)
180 {
181  HLSContext *s = h->priv_data;
182 
185  ffurl_close(s->seg_hd);
186  return 0;
187 }
188 
189 static int hls_open(URLContext *h, const char *uri, int flags)
190 {
191  HLSContext *s = h->priv_data;
192  int ret, i;
193  const char *nested_url;
194 
195  if (flags & AVIO_FLAG_WRITE)
196  return AVERROR(ENOSYS);
197 
198  h->is_streamed = 1;
199 
200  if (av_strstart(uri, "hls+", &nested_url)) {
201  av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
202  } else if (av_strstart(uri, "hls://", &nested_url)) {
203  av_log(h, AV_LOG_ERROR,
204  "No nested protocol specified. Specify e.g. hls+http://%s\n",
205  nested_url);
206  ret = AVERROR(EINVAL);
207  goto fail;
208  } else {
209  av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
210  ret = AVERROR(EINVAL);
211  goto fail;
212  }
214  "Using the hls protocol is discouraged, please try using the "
215  "hls demuxer instead. The hls demuxer should be more complete "
216  "and work as well as the protocol implementation. (If not, "
217  "please report it.) To use the demuxer, simply use %s as url.\n",
218  s->playlisturl);
219 
220  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
221  goto fail;
222 
223  if (s->n_segments == 0 && s->n_variants > 0) {
224  int max_bandwidth = 0, maxvar = -1;
225  for (i = 0; i < s->n_variants; i++) {
226  if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
227  max_bandwidth = s->variants[i]->bandwidth;
228  maxvar = i;
229  }
230  }
231  av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
232  sizeof(s->playlisturl));
233  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
234  goto fail;
235  }
236 
237  if (s->n_segments == 0) {
238  av_log(h, AV_LOG_WARNING, "Empty playlist\n");
239  ret = AVERROR(EIO);
240  goto fail;
241  }
242  s->cur_seq_no = s->start_seq_no;
243  if (!s->finished && s->n_segments >= 3)
244  s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
245 
246  return 0;
247 
248 fail:
249  hls_close(h);
250  return ret;
251 }
252 
253 static int hls_read(URLContext *h, uint8_t *buf, int size)
254 {
255  HLSContext *s = h->priv_data;
256  const char *url;
257  int ret;
258  int64_t reload_interval;
259 
260 start:
261  if (s->seg_hd) {
262  ret = ffurl_read(s->seg_hd, buf, size);
263  if (ret > 0)
264  return ret;
265  }
266  if (s->seg_hd) {
267  ffurl_close(s->seg_hd);
268  s->seg_hd = NULL;
269  s->cur_seq_no++;
270  }
271  reload_interval = s->n_segments > 0 ?
272  s->segments[s->n_segments - 1]->duration :
273  s->target_duration;
274 retry:
275  if (!s->finished) {
276  int64_t now = av_gettime_relative();
277  if (now - s->last_load_time >= reload_interval) {
278  if ((ret = parse_playlist(h, s->playlisturl)) < 0)
279  return ret;
280  /* If we need to reload the playlist again below (if
281  * there's still no more segments), switch to a reload
282  * interval of half the target duration. */
283  reload_interval = s->target_duration / 2;
284  }
285  }
286  if (s->cur_seq_no < s->start_seq_no) {
288  "skipping %d segments ahead, expired from playlist\n",
289  s->start_seq_no - s->cur_seq_no);
290  s->cur_seq_no = s->start_seq_no;
291  }
292  if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
293  if (s->finished)
294  return AVERROR_EOF;
295  while (av_gettime_relative() - s->last_load_time < reload_interval) {
297  return AVERROR_EXIT;
298  av_usleep(100*1000);
299  }
300  goto retry;
301  }
302  url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
303  av_log(h, AV_LOG_DEBUG, "opening %s\n", url);
304  ret = ffurl_open(&s->seg_hd, url, AVIO_FLAG_READ,
305  &h->interrupt_callback, NULL);
306  if (ret < 0) {
308  return AVERROR_EXIT;
309  av_log(h, AV_LOG_WARNING, "Unable to open %s\n", url);
310  s->cur_seq_no++;
311  goto retry;
312  }
313  goto start;
314 }
315 
317  .name = "hls",
318  .url_open = hls_open,
319  .url_read = hls_read,
320  .url_close = hls_close,
322  .priv_data_size = sizeof(HLSContext),
323 };